ipv6: annotate data-races around cnf.forwarding

idev->cnf.forwarding and net->ipv6.devconf_all->forwarding
might be read locklessly, add appropriate READ_ONCE()
and WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: treewide: Annotate BPF kfuncs in BTF

This commit marks kfuncs as such inside the .BTF_ids section. The upshot
of these annotations is that we'll be able to automatically generate
kfunc prototypes for downstream users. The process is as follows:

1. In source, use BTF_KFUNCS_START/END macro pair to mark kfuncs
2. During build, pahole injects into BTF a "bpf_kfunc" BTF_DECL_TAG for
each function inside BTF_KFUNCS sets
3. At runtime, vmlinux or module BTF is made available in sysfs
4. At runtime, bpftool (or similar) can look at provided BTF and
generate appropriate prototypes for functions with "bpf_kfunc" tag

To ensure future kfunc are similarly tagged, we now also return error
inside kfunc registration for untagged kfuncs. For vmlinux kfuncs,
we also WARN(), as initcall machinery does not handle errors.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/e55150ceecbf0a5d961e608941165c0bee7bc943.1706491398.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Consistently use BPF token throughout BPF verifier logic

Remove remaining direct queries to perfmon_capable() and bpf_capable()
in BPF verifier logic and instead use BPF token (if available) to make
decisions about privileges.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-9-andrii@kernel.org

bpf: Take into account BPF token when fetching helper protos

Instead of performing unconditional system-wide bpf_capable() and
perfmon_capable() calls inside bpf_base_func_proto() function (and other
similar ones) to determine eligibility of a given BPF helper for a given
program, use previously recorded BPF token during BPF_PROG_LOAD command
handling to inform the decision.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-8-andrii@kernel.org

bpf: tcp: Support arbitrary SYN Cookie.

This patch adds a new kfunc available at TC hook to support arbitrary
SYN Cookie.

The basic usage is as follows:

struct bpf_tcp_req_attrs attrs = {
.mss = mss,
.wscale_ok = wscale_ok,
.rcv_wscale = rcv_wscale, /* Server's WScale < 15 */
.snd_wscale = snd_wscale, /* Client's WScale < 15 */
.tstamp_ok = tstamp_ok,
.rcv_tsval = tsval,
.rcv_tsecr = tsecr, /* Server's Initial TSval */
.usec_ts_ok = usec_ts_ok,
.sack_ok = sack_ok,
.ecn_ok = ecn_ok,
}

skc = bpf_skc_lookup_tcp(...);
sk = (struct sock *)bpf_skc_to_tcp_sock(skc);
bpf_sk_assign_tcp_reqsk(skb, sk, attrs, sizeof(attrs));
bpf_sk_release(skc);

bpf_sk_assign_tcp_reqsk() takes skb, a listener sk, and struct
bpf_tcp_req_attrs and allocates reqsk and configures it. Then,
bpf_sk_assign_tcp_reqsk() links reqsk with skb and the listener.

The notable thing here is that we do not hold refcnt for both reqsk
and listener. To differentiate that, we mark reqsk->syncookie, which
is only used in TX for now. So, if reqsk->syncookie is 1 in RX, it
means that the reqsk is allocated by kfunc.

When skb is freed, sock_pfree() checks if reqsk->syncookie is 1,
and in that case, we set NULL to reqsk->rsk_listener before calling
reqsk_free() as reqsk does not hold a refcnt of the listener.

When the TCP stack looks up a socket from the skb, we steal the
listener from the reqsk in skb_steal_sock() and create a full sk
in cookie_v[46]_check().

The refcnt of reqsk will finally be set to 1 in tcp_get_cookie_sock()
after creating a full sk.

Note that we can extend struct bpf_tcp_req_attrs in the future when
we add a new attribute that is determined in 3WHS.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240115205514.68364-6-kuniyu@amazon.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net: filter: fix spelling mistakes

Fix spelling errors as reported by codespell.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240106065545.16855-1-rdunlap@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

xdp: reflect tail increase for MEM_TYPE_XSK_BUFF_POOL

XSK ZC Rx path calculates the size of data that will be posted to XSK Rx
queue via subtracting xdp_buff::data_end from xdp_buff::data.

In bpf_xdp_frags_increase_tail(), when underlying memory type of
xdp_rxq_info is MEM_TYPE_XSK_BUFF_POOL, add offset to data_end in tail
fragment, so that later on user space will be able to take into account
the amount of bytes added by XDP program.

Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20240124191602.566724-10-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

xsk: fix usage of multi-buffer BPF helpers for ZC XDP

Currently when packet is shrunk via bpf_xdp_adjust_tail() and memory
type is set to MEM_TYPE_XSK_BUFF_POOL, null ptr dereference happens:

[1136314.192256] BUG: kernel NULL pointer dereference, address:
0000000000000034
[1136314.203943] #PF: supervisor read access in kernel mode
[1136314.213768] #PF: error_code(0x0000) - not-present page
[1136314.223550] PGD 0 P4D 0
[1136314.230684] Oops: 0000 [#1] PREEMPT SMP NOPTI
[1136314.239621] CPU: 8 PID: 54203 Comm: xdpsock Not tainted 6.6.0+ #257
[1136314.250469] Hardware name: Intel Corporation S2600WFT/S2600WFT,
BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
[1136314.265615] RIP: 0010:__xdp_return+0x6c/0x210
[1136314.274653] Code: ad 00 48 8b 47 08 49 89 f8 a8 01 0f 85 9b 01 00 00 0f 1f 44 00 00 f0 41 ff 48 34 75 32 4c 89 c7 e9 79 cd 80 ff 83 fe 03 75 17 <f6> 41 34 01 0f 85 02 01 00 00 48 89 cf e9 22 cc 1e 00 e9 3d d2 86
[1136314.302907] RSP: 0018:ffffc900089f8db0 EFLAGS: 00010246
[1136314.312967] RAX: ffffc9003168aed0 RBX: ffff8881c3300000 RCX:
0000000000000000
[1136314.324953] RDX: 0000000000000000 RSI: 0000000000000003 RDI:
ffffc9003168c000
[1136314.336929] RBP: 0000000000000ae0 R08: 0000000000000002 R09:
0000000000010000
[1136314.348844] R10: ffffc9000e495000 R11: 0000000000000040 R12:
0000000000000001
[1136314.360706] R13: 0000000000000524 R14: ffffc9003168aec0 R15:
0000000000000001
[1136314.373298] FS: 00007f8df8bbcb80(0000) GS:ffff8897e0e00000(0000)
knlGS:0000000000000000
[1136314.386105] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1136314.396532] CR2: 0000000000000034 CR3: 00000001aa912002 CR4:
00000000007706f0
[1136314.408377] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[1136314.420173] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[1136314.431890] PKRU: 55555554
[1136314.439143] Call Trace:
[1136314.446058] <IRQ>
[1136314.452465] ? __die+0x20/0x70
[1136314.459881] ? page_fault_oops+0x15b/0x440
[1136314.468305] ? exc_page_fault+0x6a/0x150
[1136314.476491] ? asm_exc_page_fault+0x22/0x30
[1136314.484927] ? __xdp_return+0x6c/0x210
[1136314.492863] bpf_xdp_adjust_tail+0x155/0x1d0
[1136314.501269] bpf_prog_ccc47ae29d3b6570_xdp_sock_prog+0x15/0x60
[1136314.511263] ice_clean_rx_irq_zc+0x206/0xc60 [ice]
[1136314.520222] ? ice_xmit_zc+0x6e/0x150 [ice]
[1136314.528506] ice_napi_poll+0x467/0x670 [ice]
[1136314.536858] ? ttwu_do_activate.constprop.0+0x8f/0x1a0
[1136314.546010] __napi_poll+0x29/0x1b0
[1136314.553462] net_rx_action+0x133/0x270
[1136314.561619] __do_softirq+0xbe/0x28e
[1136314.569303] do_softirq+0x3f/0x60

This comes from __xdp_return() call with xdp_buff argument passed as
NULL which is supposed to be consumed by xsk_buff_free() call.

To address this properly, in ZC case, a node that represents the frag
being removed has to be pulled out of xskb_list. Introduce
appropriate xsk helpers to do such node operation and use them
accordingly within bpf_xdp_adjust_tail().

Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX")
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com> # For the xsk header part
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20240124191602.566724-4-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Revert BPF token-related functionality

This patch includes the following revert (one conflicting BPF FS
patch and three token patch sets, represented by merge commits):
- revert 0f5d5454c723 "Merge branch 'bpf-fs-mount-options-parsing-follow-ups'";
- revert 750e785796bb "bpf: Support uid and gid when mounting bpffs";
- revert 733763285acf "Merge branch 'bpf-token-support-in-libbpf-s-bpf-object'";
- revert c35919dcce28 "Merge branch 'bpf-token-and-bpf-fs-based-delegation'".

Link: https://lore.kernel.org/bpf/CAHk-=wg7JuFYwGy=GOMbRCtOL+jwSQsdUaBsRWkDVYbxipbM5A@mail.gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

bpf: Use nla_ok() instead of checking nla_len directly

nla_len may also be too short to be sane, in which case after
recent changes nla_len() will return a wrapped value.

Fixes: 172db56d90d2 ("netlink: Return unsigned value for nla_len()")
Reported-by: syzbot+f43a23b6e622797c7a28@syzkaller.appspotmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/bpf/20231218231904.260440-1-kuba@kernel.org

net: Namespace-ify sysctl_optmem_max

optmem_max being used in tx zerocopy,
we want to be able to control it on a netns basis.

Following patch changes two tests.

Tested:

oqq130:~# cat /proc/sys/net/core/optmem_max
131072
oqq130:~# echo 1000000 >/proc/sys/net/core/optmem_max
oqq130:~# cat /proc/sys/net/core/optmem_max
1000000
oqq130:~# unshare -n
oqq130:~# cat /proc/sys/net/core/optmem_max
131072
oqq130:~# exit
logout
oqq130:~# cat /proc/sys/net/core/optmem_max
1000000

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: consistently use BPF token throughout BPF verifier logic

Remove remaining direct queries to perfmon_capable() and bpf_capable()
in BPF verifier logic and instead use BPF token (if available) to make
decisions about privileges.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231130185229.2688956-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: take into account BPF token when fetching helper protos

Instead of performing unconditional system-wide bpf_capable() and
perfmon_capable() calls inside bpf_base_func_proto() function (and other
similar ones) to determine eligibility of a given BPF helper for a given
program, use previously recorded BPF token during BPF_PROG_LOAD command
handling to inform the decision.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231130185229.2688956-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tcp: Don't pass cookie to __cookie_v[46]_check().

tcp_hdr(skb) and SYN Cookie are passed to __cookie_v[46]_check(), but
none of the callers passes cookie other than ntohl(th->ack_seq) - 1.

Let's fetch it in __cookie_v[46]_check() instead of passing the cookie
over and over.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231129022924.96156-5-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: sockmap, updating the sg structure should also update curr

Curr pointer should be updated when the sg structure is shifted.

Fixes: 7246d8ed4dcce ("bpf: helper to pop data from messages")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20231206232706.374377-3-john.fastabend@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf, netkit: Add indirect call wrapper for fetching peer dev

ndo_get_peer_dev is used in tcx BPF fast path, therefore make use of
indirect call wrapper and therefore optimize the bpf_redirect_peer()
internal handling a bit. Add a small skb_get_peer_dev() wrapper which
utilizes the INDIRECT_CALL_1() macro instead of open coding.

Future work could potentially add a peer pointer directly into struct
net_device in future and convert veth and netkit over to use it so
that eventually ndo_get_peer_dev can be removed.

Co-developed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20231114004220.6495-7-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Fix dev's rx stats for bpf_redirect_peer traffic

Traffic redirected by bpf_redirect_peer() (used by recent CNIs like Cilium)
is not accounted for in the RX stats of supported devices (that is, veth
and netkit), confusing user space metrics collectors such as cAdvisor [0],
as reported by Youlun.

Fix it by calling dev_sw_netstats_rx_add() in skb_do_redirect(), to update
RX traffic counters. Devices that support ndo_get_peer_dev _must_ use the
@tstats per-CPU counters (instead of @lstats, or @dstats).

To make this more fool-proof, error out when ndo_get_peer_dev is set but
@tstats are not selected.

[0] Specifically, the "container_network_receive_{byte,packet}s_total"
counters are affected.

Fixes: 9aa1206e8f48 ("bpf: Add redirect_peer helper")
Reported-by: Youlun Zhang <zhangyoulun@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/20231114004220.6495-6-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Add __bpf_kfunc_{start,end}_defs macros

BPF kfuncs are meant to be called from BPF programs. Accordingly, most
kfuncs are not called from anywhere in the kernel, which the
-Wmissing-prototypes warning is unhappy about. We've peppered
__diag_ignore_all("-Wmissing-prototypes", ... everywhere kfuncs are
defined in the codebase to suppress this warning.

This patch adds two macros meant to bound one or many kfunc definitions.
All existing kfunc definitions which use these __diag calls to suppress
-Wmissing-prototypes are migrated to use the newly-introduced macros.
A new __diag_ignore_all - for "-Wmissing-declarations" - is added to the
__bpf_kfunc_start_defs macro based on feedback from Andrii on an earlier
version of this patch [0] and another recent mailing list thread [1].

In the future we might need to ignore different warnings or do other
kfunc-specific things. This change will make it easier to make such
modifications for all kfunc defs.

[0]: https://lore.kernel.org/bpf/CAEf4BzaE5dRWtK6RPLnjTW-MW9sx9K3Fn6uwqCTChK2Dcb1Xig@mail.gmail.com/
[1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20231031215625.2343848-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net, bpf: Add a warning if NAPI cb missed xdp_do_flush().

A few drivers were missing a xdp_do_flush() invocation after
XDP_REDIRECT.

Add three helper functions each for one of the per-CPU lists. Return
true if the per-CPU list is non-empty and flush the list.

Add xdp_do_check_flushed() which invokes each helper functions and
creates a warning if one of the functions had a non-empty list.

Hide everything behind CONFIG_DEBUG_NET.

Suggested-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20231016125738.Yt79p1uF@linutronix.de

bpf: Implement cgroup sockaddr hooks for unix sockets

These hooks allows intercepting connect(), getsockname(),
getpeername(), sendmsg() and recvmsg() for unix sockets. The unix
socket hooks get write access to the address length because the
address length is not fixed when dealing with unix sockets and
needs to be modified when a unix socket address is modified by
the hook. Because abstract socket unix addresses start with a
NUL byte, we cannot recalculate the socket address in kernelspace
after running the hook by calculating the length of the unix socket
path using strlen().

These hooks can be used when users want to multiplex syscall to a
single unix socket to multiple different processes behind the scenes
by redirecting the connect() and other syscalls to process specific
sockets.

We do not implement support for intercepting bind() because when
using bind() with unix sockets with a pathname address, this creates
an inode in the filesystem which must be cleaned up. If we rewrite
the address, the user might try to clean up the wrong file, leaking
the socket in the filesystem where it is never cleaned up. Until we
figure out a solution for this (and a use case for intercepting bind()),
we opt to not allow rewriting the sockaddr in bind() calls.

We also implement recvmsg() support for connected streams so that
after a connect() that is modified by a sockaddr hook, any corresponding
recmvsg() on the connected socket can also be modified to make the
connected program think it is connected to the "intended" remote.

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-5-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Add bpf_sock_addr_set_sun_path() to allow writing unix sockaddr from bpf

As prep for adding unix socket support to the cgroup sockaddr hooks,
let's add a kfunc bpf_sock_addr_set_sun_path() that allows modifying a unix
sockaddr from bpf. While this is already possible for AF_INET and AF_INET6,
we'll need this kfunc when we add unix socket support since modifying the
address for those requires modifying both the address and the sockaddr
length.

Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-4-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Derive source IP addr via bpf_*_fib_lookup()

Extend the bpf_fib_lookup() helper by making it to return the source
IPv4/IPv6 address if the BPF_FIB_LOOKUP_SRC flag is set.

For example, the following snippet can be used to derive the desired
source IP address:

struct bpf_fib_lookup p = { .ipv4_dst = ip4->daddr };

ret = bpf_skb_fib_lookup(skb, p, sizeof(p),
BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH);
if (ret != BPF_FIB_LKUP_RET_SUCCESS)
return TC_ACT_SHOT;

/* the p.ipv4_src now contains the source address */

The inability to derive the proper source address may cause malfunctions
in BPF-based dataplanes for hosts containing netdevs with more than one
routable IP address or for multi-homed hosts.

For example, Cilium implements packet masquerading in BPF. If an
egressing netdev to which the Cilium's BPF prog is attached has
multiple IP addresses, then only one [hardcoded] IP address can be used for
masquerading. This breaks connectivity if any other IP address should have
been selected instead, for example, when a public and private addresses
are attached to the same egress interface.

The change was tested with Cilium [1].

Nikolay Aleksandrov helped to figure out the IPv6 addr selection.

[1]: https://github.com/cilium/cilium/pull/28283

Signed-off-by: Martynas Pumputis <m@lambda.lt>
Link: https://lore.kernel.org/r/20231007081415.33502-2-m@lambda.lt
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign

Currently the bpf_sk_assign helper in tc BPF context refuses SO_REUSEPORT
sockets. This means we can't use the helper to steer traffic to Envoy,
which configures SO_REUSEPORT on its sockets. In turn, we're blocked
from removing TPROXY from our setup.

The reason that bpf_sk_assign refuses such sockets is that the
bpf_sk_lookup helpers don't execute SK_REUSEPORT programs. Instead,
one of the reuseport sockets is selected by hash. This could cause
dispatch to the "wrong" socket:

sk = bpf_sk_lookup_tcp(...) // select SO_REUSEPORT by hash
bpf_sk_assign(skb, sk) // SK_REUSEPORT wasn't executed

Fixing this isn't as simple as invoking SK_REUSEPORT from the lookup
helpers unfortunately. In the tc context, L2 headers are at the start
of the skb, while SK_REUSEPORT expects L3 headers instead.

Instead, we execute the SK_REUSEPORT program when the assigned socket
is pulled out of the skb, further up the stack. This creates some
trickiness with regards to refcounting as bpf_sk_assign will put both
refcounted and RCU freed sockets in skb->sk. reuseport sockets are RCU
freed. We can infer that the sk_assigned socket is RCU freed if the
reuseport lookup succeeds, but convincing yourself of this fact isn't
straight forward. Therefore we defensively check refcounting on the
sk_assign sock even though it's probably not required in practice.

Fixes: 8e368dc72e86 ("bpf: Fix use of sk->sk_reuseport from sk_assign")
Fixes: cf7fbe660f2d ("bpf: Add socket assign support")
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Joe Stringer <joe@cilium.io>
Link: https://lore.kernel.org/bpf/CACAyw98+qycmpQzKupquhkxbvWK4OFyDuuLMBNROnfWMZxUWeA@mail.gmail.com/
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-7-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: reject unhashed sockets in bpf_sk_assign

The semantics for bpf_sk_assign are as follows:

sk = some_lookup_func()
bpf_sk_assign(skb, sk)
bpf_sk_release(sk)

That is, the sk is not consumed by bpf_sk_assign. The function
therefore needs to make sure that sk lives long enough to be
consumed from __inet_lookup_skb. The path through the stack for a
TCPv4 packet is roughly:

netif_receive_skb_core: takes RCU read lock
__netif_receive_skb_core:
sch_handle_ingress:
tcf_classify:
bpf_sk_assign()
deliver_ptype_list_skb:
deliver_skb:
ip_packet_type->func == ip_rcv:
ip_rcv_core:
ip_rcv_finish_core:
dst_input:
ip_local_deliver:
ip_local_deliver_finish:
ip_protocol_deliver_rcu:
tcp_v4_rcv:
__inet_lookup_skb:
skb_steal_sock

The existing helper takes advantage of the fact that everything
happens in the same RCU critical section: for sockets with
SOCK_RCU_FREE set bpf_sk_assign never takes a reference.
skb_steal_sock then checks SOCK_RCU_FREE again and does sock_put
if necessary.

This approach assumes that SOCK_RCU_FREE is never set on a sk
between bpf_sk_assign and skb_steal_sock, but this invariant is
violated by unhashed UDP sockets. A new UDP socket is created
in TCP_CLOSE state but without SOCK_RCU_FREE set. That flag is only
added in udp_lib_get_port() which happens when a socket is bound.

When bpf_sk_assign was added it wasn't possible to access unhashed
UDP sockets from BPF, so this wasn't a problem. This changed
in commit 0c48eefae712 ("sock_map: Lift socket state restriction
for datagram sockets"), but the helper wasn't adjusted accordingly.
The following sequence of events will therefore lead to a refcount
leak:

1. Add socket(AF_INET, SOCK_DGRAM) to a sockmap.
2. Pull socket out of sockmap and bpf_sk_assign it. Since
SOCK_RCU_FREE is not set we increment the refcount.
3. bind() or connect() the socket, setting SOCK_RCU_FREE.
4. skb_steal_sock will now set refcounted = false due to
SOCK_RCU_FREE.
5. tcp_v4_rcv() skips sock_put().

Fix the problem by rejecting unhashed sockets in bpf_sk_assign().
This matches the behaviour of __inet_lookup_skb which is ultimately
the goal of bpf_sk_assign().

Fixes: cf7fbe660f2d ("bpf: Add socket assign support")
Cc: Joe Stringer <joe@cilium.io>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-2-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Add fd-based tcx multi-prog infra with link support

This work refactors and adds a lightweight extension ("tcx") to the tc BPF
ingress and egress data path side for allowing BPF program management based
on fds via bpf() syscall through the newly added generic multi-prog API.
The main goal behind this work which we also presented at LPC [0] last year
and a recent update at LSF/MM/BPF this year [3] is to support long-awaited
BPF link functionality for tc BPF programs, which allows for a model of safe
ownership and program detachment.

Given the rise in tc BPF users in cloud native environments, this becomes
necessary to avoid hard to debug incidents either through stale leftover
programs or 3rd party applications accidentally stepping on each others toes.
As a recap, a BPF link represents the attachment of a BPF program to a BPF
hook point. The BPF link holds a single reference to keep BPF program alive.
Moreover, hook points do not reference a BPF link, only the application's
fd or pinning does. A BPF link holds meta-data specific to attachment and
implements operations for link creation, (atomic) BPF program update,
detachment and introspection. The motivation for BPF links for tc BPF programs
is multi-fold, for example:

- From Meta: "It's especially important for applications that are deployed
fleet-wide and that don't "control" hosts they are deployed to. If such
application crashes and no one notices and does anything about that, BPF
program will keep running draining resources or even just, say, dropping
packets. We at FB had outages due to such permanent BPF attachment
semantics. With fd-based BPF link we are getting a framework, which allows
safe, auto-detachable behavior by default, unless application explicitly
opts in by pinning the BPF link." [1]

- From Cilium-side the tc BPF programs we attach to host-facing veth devices
and phys devices build the core datapath for Kubernetes Pods, and they
implement forwarding, load-balancing, policy, EDT-management, etc, within
BPF. Currently there is no concept of 'safe' ownership, e.g. we've recently
experienced hard-to-debug issues in a user's staging environment where
another Kubernetes application using tc BPF attached to the same prio/handle
of cls_bpf, accidentally wiping all Cilium-based BPF programs from underneath
it. The goal is to establish a clear/safe ownership model via links which
cannot accidentally be overridden. [0,2]

BPF links for tc can co-exist with non-link attachments, and the semantics are
in line also with XDP links: BPF links cannot replace other BPF links, BPF
links cannot replace non-BPF links, non-BPF links cannot replace BPF links and
lastly only non-BPF links can replace non-BPF links. In case of Cilium, this
would solve mentioned issue of safe ownership model as 3rd party applications
would not be able to accidentally wipe Cilium programs, even if they are not
BPF link aware.

Earlier attempts [4] have tried to integrate BPF links into core tc machinery
to solve cls_bpf, which has been intrusive to the generic tc kernel API with
extensions only specific to cls_bpf and suboptimal/complex since cls_bpf could
be wiped from the qdisc also. Locking a tc BPF program in place this way, is
getting into layering hacks given the two object models are vastly different.

We instead implemented the tcx (tc 'express') layer which is an fd-based tc BPF
attach API, so that the BPF link implementation blends in naturally similar to
other link types which are fd-based and without the need for changing core tc
internal APIs. BPF programs for tc can then be successively migrated from classic
cls_bpf to the new tc BPF link without needing to change the program's source
code, just the BPF loader mechanics for attaching is sufficient.

For the current tc framework, there is no change in behavior with this change
and neither does this change touch on tc core kernel APIs. The gist of this
patch is that the ingress and egress hook have a lightweight, qdisc-less
extension for BPF to attach its tc BPF programs, in other words, a minimal
entry point for tc BPF. The name tcx has been suggested from discussion of
earlier revisions of this work as a good fit, and to more easily differ between
the classic cls_bpf attachment and the fd-based one.

For the ingress and egress tcx points, the device holds a cache-friendly array
with program pointers which is separated from control plane (slow-path) data.
Earlier versions of this work used priority to determine ordering and expression
of dependencies similar as with classic tc, but it was challenged that for
something more future-proof a better user experience is required. Hence this
resulted in the design and development of the generic attach/detach/query API
for multi-progs. See prior patch with its discussion on the API design. tcx is
the first user and later we plan to integrate also others, for example, one
candidate is multi-prog support for XDP which would benefit and have the same
'look and feel' from API perspective.

The goal with tcx is to have maximum compatibility to existing tc BPF programs,
so they don't need to be rewritten specifically. Compatibility to call into
classic tcf_classify() is also provided in order to allow successive migration
or both to cleanly co-exist where needed given its all one logical tc layer and
the tcx plus classic tc cls/act build one logical overall processing pipeline.

tcx supports the simplified return codes TCX_NEXT which is non-terminating (go
to next program) and terminating ones with TCX_PASS, TCX_DROP, TCX_REDIRECT.
The fd-based API is behind a static key, so that when unused the code is also
not entered. The struct tcx_entry's program array is currently static, but
could be made dynamic if necessary at a point in future. The a/b pair swap
design has been chosen so that for detachment there are no allocations which
otherwise could fail.

The work has been tested with tc-testing selftest suite which all passes, as
well as the tc BPF tests from the BPF CI, and also with Cilium's L4LB.

Thanks also to Nikolay Aleksandrov and Martin Lau for in-depth early reviews
of this work.

[0] https://lpc.events/event/16/contributions/1353/
[1] https://lore.kernel.org/bpf/CAEf4BzbokCJN33Nw_kg82sO=xppXnKWEncGTWCTB9vGCmLB6pw@mail.gmail.com
[2] https://colocatedeventseu2023.sched.com/event/1Jo6O/tales-from-an-ebpf-programs-murder-mystery-hemanth-malla-guillaume-fournier-datadog
[3] http://vger.kernel.org/bpfconf2023_material/tcx_meta_netdev_borkmann.pdf
[4] https://lore.kernel.org/bpf/20210604063116.234316-1-memxor@gmail.com

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230719140858.13224-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

xsk: add support for AF_XDP multi-buffer on Rx path

Add multi-buffer support for AF_XDP by extending the XDP multi-buffer
support to be reflected in user-space when a packet is redirected to
an AF_XDP socket.

In the XDP implementation, the NIC driver builds the xdp_buff from the
first frag of the packet and adds any subsequent frags in the skb_shinfo
area of the xdp_buff. In AF_XDP core, XDP buffers are allocated from
xdp_sock's pool and data is copied from the driver's xdp_buff and frags.

Once an allocated XDP buffer is full and there is still data to be
copied, the 'XDP_PKT_CONTD' flag in'options' field of the corresponding
xdp ring descriptor is set and passed to the application. When application
sees the aforementioned flag set it knows there is pending data for this
packet that will be carried in the following descriptors. If there is no
more data to be copied, the flag in 'options' field is cleared for that
descriptor signalling EOP to the application.

If application reads a batch of descriptors using for example the libxdp
interfaces, it is not guaranteed that the batch will end with a full
packet. It might end in the middle of a packet and the rest of the frames
of that packet will arrive at the beginning of the next batch.

AF_XDP ensures that only a complete packet (along with all its frags) is
sent to application.

Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@intel.com>
Link: https://lore.kernel.org/r/20230719132421.584801-6-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail()

Syzkaller reported the following issue:
=======================================
Too BIG xdp->frame_sz = 131072
WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline]
WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103
...
Call Trace:
<TASK>
bpf_prog_4add87e5301a4105+0x1a/0x1c
__bpf_prog_run include/linux/filter.h:600 [inline]
bpf_prog_run_xdp include/linux/filter.h:775 [inline]
bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721
netif_receive_generic_xdp net/core/dev.c:4807 [inline]
do_xdp_generic+0x35c/0x770 net/core/dev.c:4866
tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919
tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043
call_write_iter include/linux/fs.h:1871 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x650/0xe40 fs/read_write.c:584
ksys_write+0x12f/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87
("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper
Dangaard Brouer <jbrouer@redhat.com> noted that after introducing the
xdp_init_buff() which all XDP driver use - it's safe to remove this
check. The original intend was to catch cases where XDP drivers have
not been updated to use xdp.frame_sz, but that is not longer a concern
(since xdp_init_buff).

Running the initial syzkaller repro it was discovered that the
contiguous physical memory allocation is used for both xdp paths in
tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also
stated by Jesper Dangaard Brouer <jbrouer@redhat.com> that XDP can
work on higher order pages, as long as this is contiguous physical
memory (e.g. a page).

Reported-and-tested-by: syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000774b9205f1d8a80d@google.com/T/
Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a
Link: https://lore.kernel.org/all/20230725155403.796-1-andrew.kanner@gmail.com/T/
Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine")
Signed-off-by: Andrew Kanner <andrew.kanner@gmail.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20230803190316.2380231-1-andrew.kanner@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: Fix bpf socket lookup from tc/xdp to respect socket VRF bindings

When calling bpf_sk_lookup_tcp(), bpf_sk_lookup_udp() or
bpf_skc_lookup_tcp() from tc/xdp ingress, VRF socket bindings aren't
respoected, i.e. unbound sockets are returned, and bound sockets aren't
found.

VRF binding is determined by the sdif argument to sk_lookup(), however
when called from tc the IP SKB control block isn't initialized and thus
inet{,6}_sdif() always returns 0.

Fix by calculating sdif for the tc/xdp flows by observing the device's
l3 enslaved state.

The cg/sk_skb hooking points which are expected to support
inet{,6}_sdif() pass sdif=-1 which makes __bpf_skc_lookup() use the
existing logic.

Fixes: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF")
Signed-off-by: Gilad Sever <gilad9366@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Reviewed-by: Eyal Birger <eyal.birger@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Cc: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/bpf/20230621104211.301902-4-gilad9366@gmail.com

bpf: Call __bpf_sk_lookup()/__bpf_skc_lookup() directly via TC hookpoint

skb->dev always exists in the tc flow. There is no need to use
bpf_skc_lookup(), bpf_sk_lookup() from this code path.

This change facilitates fixing the tc flow to be VRF aware.

Signed-off-by: Gilad Sever <gilad9366@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Reviewed-by: Eyal Birger <eyal.birger@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230621104211.301902-3-gilad9366@gmail.com

bpf: Factor out socket lookup functions for the TC hookpoint.

Change BPF helper socket lookup functions to use TC specific variants:
bpf_tc_sk_lookup_tcp() / bpf_tc_sk_lookup_udp() / bpf_tc_skc_lookup_tcp()
instead of sharing implementation with the cg / sk_skb hooking points.
This allows introducing a separate logic for the TC flow.

The tc functions are identical to the original code.

Signed-off-by: Gilad Sever <gilad9366@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Reviewed-by: Eyal Birger <eyal.birger@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230621104211.301902-2-gilad9366@gmail.com

bpf/xdp: optimize bpf_xdp_pointer to avoid reading sinfo

Currently we observed a significant performance degradation in
samples/bpf xdp1 and xdp2, due XDP multibuffer "xdp.frags" handling,
added in commit 772251742262 ("samples/bpf: fixup some tools to be able
to support xdp multibuffer").

This patch reduce the overhead by avoiding to read/load shared_info
(sinfo) memory area, when XDP packet don't have any frags. This improves
performance because sinfo is located in another cacheline.

Function bpf_xdp_pointer() is used by BPF helpers bpf_xdp_load_bytes()
and bpf_xdp_store_bytes(). As a help to reviewers, xdp_get_buff_len() can
potentially access sinfo, but it uses xdp_buff_has_frags() flags bit check
to avoid accessing sinfo in no-frags case.

The likely/unlikely instrumentation lays out asm code such that sinfo
access isn't interleaved with no-frags case (checked on GCC 12.2.1-4).
The generated asm code is more compact towards the no-frags case.

The BPF kfunc bpf_dynptr_slice() also use bpf_xdp_pointer(). Thus, it
should also take effect for that.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/168563651438.3436004.17735707525651776648.stgit@firesoul
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add table ID to bpf_fib_lookup BPF helper

Add ability to specify routing table ID to the `bpf_fib_lookup` BPF
helper.

A new field `tbid` is added to `struct bpf_fib_lookup` used as
parameters to the `bpf_fib_lookup` BPF helper.

When the helper is called with the `BPF_FIB_LOOKUP_DIRECT` and
`BPF_FIB_LOOKUP_TBID` flags the `tbid` field in `struct bpf_fib_lookup`
will be used as the table ID for the fib lookup.

If the `tbid` does not exist the fib lookup will fail with
`BPF_FIB_LKUP_RET_NOT_FWDED`.

The `tbid` field becomes a union over the vlan related output fields
in `struct bpf_fib_lookup` and will be zeroed immediately after usage.

This functionality is useful in containerized environments.

For instance, if a CNI wants to dictate the next-hop for traffic leaving
a container it can create a container-specific routing table and perform
a fib lookup against this table in a "host-net-namespace-side" TC program.

This functionality also allows `ip rule` like functionality at the TC
layer, allowing an eBPF program to pick a routing table based on some
aspect of the sk_buff.

As a concrete use case, this feature will be used in Cilium's SRv6 L3VPN
datapath.

When egress traffic leaves a Pod an eBPF program attached by Cilium will
determine which VRF the egress traffic should target, and then perform a
FIB lookup in a specific table representing this VRF's FIB.

Signed-off-by: Louis DeLosSantos <louis.delos.devel@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230505-bpf-add-tbid-fib-lookup-v2-1-0a31c22c748c@gmail.com

bpf: Add bpf_sock_destroy kfunc

The socket destroy kfunc is used to forcefully terminate sockets from
certain BPF contexts. We plan to use the capability in Cilium
load-balancing to terminate client sockets that continue to connect to
deleted backends. The other use case is on-the-fly policy enforcement
where existing socket connections prevented by policies need to be
forcefully terminated. The kfunc also allows terminating sockets that may
or may not be actively sending traffic.

The kfunc can currently be called only from BPF TCP and UDP iterators
where users can filter, and terminate selected sockets. More
specifically, it can only be called from BPF contexts that ensure
socket locking in order to allow synchronous execution of protocol
specific `diag_destroy` handlers. The previous commit that batches UDP
sockets during iteration facilitated a synchronous invocation of the UDP
destroy callback from BPF context by skipping socket locks in
`udp_abort`. TCP iterator already supported batching of sockets being
iterated. To that end, `tracing_iter_filter` callback filter is added so
that verifier can restrict the kfunc to programs with `BPF_TRACE_ITER`
attach type, and reject other programs.

The kfunc takes `sock_common` type argument, even though it expects, and
casts them to a `sock` pointer. This enables the verifier to allow the
sock_destroy kfunc to be called for TCP with `sock_common` and UDP with
`sock` structs. Furthermore, as `sock_common` only has a subset of
certain fields of `sock`, casting pointer to the latter type might not
always be safe for certain sockets like request sockets, but these have a
special handling in the diag_destroy handlers.

Additionally, the kfunc is defined with `KF_TRUSTED_ARGS` flag to avoid the
cases where a `PTR_TO_BTF_ID` sk is obtained by following another pointer.
eg. getting a sk pointer (may be even NULL) by following another sk
pointer. The pointer socket argument passed in TCP and UDP iterators is
tagged as `PTR_TRUSTED` in {tcp,udp}_reg_info. The TRUSTED arg changes
are contributed by Martin KaFai Lau <martin.lau@kernel.org>.

Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Link: https://lore.kernel.org/r/20230519225157.760788-8-aditi.ghag@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Emit struct bpf_tcp_sock type in vmlinux BTF

In one of our internal testing, we found a case where
- uapi struct bpf_tcp_sock is in vmlinux.h where vmlinux.h is not
generated from the testing kernel
- struct bpf_tcp_sock is not in vmlinux BTF

The above combination caused bpf load failure as the following
memory access
struct bpf_tcp_sock *tcp_sock = ...;
... tcp_sock->snd_cwnd ...
needs CORE relocation but the relocation cannot be resolved since
the kernel BTF does not have corresponding type.

Similar to other previous cases (nf_conn___init, tcp6_sock, mctcp_sock, etc.),
add the type to vmlinux BTF with BTF_EMIT_TYPE macro.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230502180543.1832140-1-yhs@fb.com

bpf: minimal support for programs hooked into netfilter framework

This adds minimal support for BPF_PROG_TYPE_NETFILTER bpf programs
that will be invoked via the NF_HOOK() points in the ip stack.

Invocation incurs an indirect call. This is not a necessity: Its
possible to add 'DEFINE_BPF_DISPATCHER(nf_progs)' and handle the
program invocation with the same method already done for xdp progs.

This isn't done here to keep the size of this chunk down.

Verifier restricts verdicts to either DROP or ACCEPT.

Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20230421170300.24115-3-fw@strlen.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Set skb redirect and from_ingress info in __bpf_tx_skb

There are some use-cases where it is desirable to use bpf_redirect()
in combination with ifb device, which currently is not supported, for
example, around filtering inbound traffic with BPF to then push it to
ifb which holds the qdisc for shaping in contrast to doing that on the
egress device.

Toke mentions the following case related to OpenWrt:

Because there's not always a single egress on the other side. These are
mainly home routers, which tend to have one or more WiFi devices bridged
to one or more ethernet ports on the LAN side, and a single upstream WAN
port. And the objective is to control the total amount of traffic going
over the WAN link (in both directions), to deal with bufferbloat in the
ISP network (which is sadly still all too prevalent).

In this setup, the traffic can be split arbitrarily between the links
on the LAN side, and the only "single bottleneck" is the WAN link. So we
install both egress and ingress shapers on this, configured to something
like 95-98% of the true link bandwidth, thus moving the queues into the
qdisc layer in the router. It's usually necessary to set the ingress
bandwidth shaper a bit lower than the egress due to being "downstream"
of the bottleneck link, but it does work surprisingly well.

We usually use something like a matchall filter to put all ingress
traffic on the ifb, so doing the redirect from BPF has not been an
immediate requirement thus far. However, it does seem a bit odd that
this is not possible, and we do have a BPF-based filter that layers on
top of this kind of setup, which currently uses u32 as the ingress
filter and so it could presumably be improved to use BPF instead if
that was available.

Reported-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reported-by: Yafang Shao <laoar.shao@gmail.com>
Reported-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://git.openwrt.org/?p=project/qosify.git;a=blob;f=README
Link: https://lore.kernel.org/bpf/875y9yzbuy.fsf@toke.dk
Link: https://lore.kernel.org/r/8cebc8b2b6e967e10cbafe2ffd6795050e74accd.1681739137.git.daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Teach verifier that certain helpers accept NULL pointer.

bpf_[sk|inode|task|cgrp]_storage_[get|delete]() and bpf_get_socket_cookie() helpers
perform run-time check that sk|inode|task|cgrp pointer != NULL.
Teach verifier about this fact and allow bpf programs to pass
PTR_TO_BTF_ID | PTR_MAYBE_NULL into such helpers.
It will be used in the subsequent patch that will do
bpf_sk_storage_get(.., skb->sk, ...);
Even when 'skb' pointer is trusted the 'sk' pointer may be NULL.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230404045029.82870-5-alexei.starovoitov@gmail.com

bpf: Remove unused arguments from btf_struct_access().

Remove unused arguments from btf_struct_access() callback.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230404045029.82870-3-alexei.starovoitov@gmail.com

bpf: Invoke btf_struct_access() callback only for writes.

Remove duplicated if (atype == BPF_READ) btf_struct_access() from
btf_struct_access() callback and invoke it only for writes. This is
possible to do because currently btf_struct_access() custom callback
always delegates to generic btf_struct_access() helper for BPF_READ
accesses.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230404045029.82870-2-alexei.starovoitov@gmail.com

neighbour: switch to standard rcu, instead of rcu_bh

rcu_bh is no longer a win, especially for objects freed
with standard call_rcu().

Switch neighbour code to no longer disable BH when not necessary.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: skbuff: rename __pkt_vlan_present_offset to __mono_tc_offset

vlan_present is gone since
commit 354259fa73e2 ("net: remove skb->vlan_present")
rename the offset field to what BPF is currently looking
for in this byte - mono_delivery_time and tc_at_ingress.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230321014115.997841-2-kuba@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

neighbour: annotate lockless accesses to n->nud_state

We have many lockless accesses to n->nud_state.

Before adding another one in the following patch,
add annotations to readers and writers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: allow ctx writes using BPF_ST_MEM instruction

Lift verifier restriction to use BPF_ST_MEM instructions to write to
context data structures. This requires the following changes:
- verifier.c:do_check() for BPF_ST updated to:
- no longer forbid writes to registers of type PTR_TO_CTX;
- track dst_reg type in the env->insn_aux_data[...].ptr_type field
(same way it is done for BPF_STX and BPF_LDX instructions).
- verifier.c:convert_ctx_access() and various callbacks invoked by
it are updated to handled BPF_ST instruction alongside BPF_STX.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230304011247.566040-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Make bpf_get_current_[ancestor_]cgroup_id() available for all program types

These helpers are safe to call from any context and there's no reason to
restrict access to them. Remove them from bpf_trace and filter lists and add
to bpf_base_func_proto() under perfmon_capable().

v2: After consulting with Andrii, relocated in bpf_base_func_proto() so that
they require bpf_capable() but not perfomon_capable() as it doesn't read
from or affect others on the system.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/ZAD8QyoszMZiTzBY@slm.duckdns.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr

Two new kfuncs are added, bpf_dynptr_slice and bpf_dynptr_slice_rdwr.
The user must pass in a buffer to store the contents of the data slice
if a direct pointer to the data cannot be obtained.

For skb and xdp type dynptrs, these two APIs are the only way to obtain
a data slice. However, for other types of dynptrs, there is no
difference between bpf_dynptr_slice(_rdwr) and bpf_dynptr_data.

For skb type dynptrs, the data is copied into the user provided buffer
if any of the data is not in the linear portion of the skb. For xdp type
dynptrs, the data is copied into the user provided buffer if the data is
between xdp frags.

If the skb is cloned and a call to bpf_dynptr_data_rdwr is made, then
the skb will be uncloned (see bpf_unclone_prologue()).

Please note that any bpf_dynptr_write() automatically invalidates any prior
data slices of the skb dynptr. This is because the skb may be cloned or
may need to pull its paged buffer into the head. As such, any
bpf_dynptr_write() will automatically have its prior data slices
invalidated, even if the write is to data in the skb head of an uncloned
skb. Please note as well that any other helper calls that change the
underlying packet buffer (eg bpf_skb_pull_data()) invalidates any data
slices of the skb dynptr as well, for the same reasons.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-10-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add xdp dynptrs

Add xdp dynptrs, which are dynptrs whose underlying pointer points
to a xdp_buff. The dynptr acts on xdp data. xdp dynptrs have two main
benefits. One is that they allow operations on sizes that are not
statically known at compile-time (eg variable-sized accesses).
Another is that parsing the packet data through dynptrs (instead of
through direct access of xdp->data and xdp->data_end) can be more
ergonomic and less brittle (eg does not need manual if checking for
being within bounds of data_end).

For reads and writes on the dynptr, this includes reading/writing
from/to and across fragments. Data slices through the bpf_dynptr_data
API are not supported; instead bpf_dynptr_slice() and
bpf_dynptr_slice_rdwr() should be used.

For examples of how xdp dynptrs can be used, please see the attached
selftests.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-9-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add skb dynptrs

Add skb dynptrs, which are dynptrs whose underlying pointer points
to a skb. The dynptr acts on skb data. skb dynptrs have two main
benefits. One is that they allow operations on sizes that are not
statically known at compile-time (eg variable-sized accesses).
Another is that parsing the packet data through dynptrs (instead of
through direct access of skb->data and skb->data_end) can be more
ergonomic and less brittle (eg does not need manual if checking for
being within bounds of data_end).

For bpf prog types that don't support writes on skb data, the dynptr is
read-only (bpf_dynptr_write() will return an error)

For reads and writes through the bpf_dynptr_read() and bpf_dynptr_write()
interfaces, reading and writing from/to data in the head as well as from/to
non-linear paged buffers is supported. Data slices through the
bpf_dynptr_data API are not supported; instead bpf_dynptr_slice() and
bpf_dynptr_slice_rdwr() (added in subsequent commit) should be used.

For examples of how skb dynptrs can be used, please see the attached
selftests.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-8-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add BPF_FIB_LOOKUP_SKIP_NEIGH for bpf_fib_lookup

The bpf_fib_lookup() also looks up the neigh table.
This was done before bpf_redirect_neigh() was added.

In the use case that does not manage the neigh table
and requires bpf_fib_lookup() to lookup a fib to
decide if it needs to redirect or not, the bpf prog can
depend only on using bpf_redirect_neigh() to lookup the
neigh. It also keeps the neigh entries fresh and connected.

This patch adds a bpf_fib_lookup flag, SKIP_NEIGH, to avoid
the double neigh lookup when the bpf prog always call
bpf_redirect_neigh() to do the neigh lookup. The params->smac
output is skipped together when SKIP_NEIGH is set because
bpf_redirect_neigh() will figure out the smac also.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230217205515.3583372-1-martin.lau@linux.dev

bpf: bpf_fib_lookup should not return neigh in NUD_FAILED state

The bpf_fib_lookup() helper does not only look up the fib (ie. route)
but it also looks up the neigh. Before returning the neigh, the helper
does not check for NUD_VALID. When a neigh state (neigh->nud_state)
is in NUD_FAILED, its dmac (neigh->ha) could be all zeros. The helper
still returns SUCCESS instead of NO_NEIGH in this case. Because of the
SUCCESS return value, the bpf prog directly uses the returned dmac
and ends up filling all zero in the eth header.

This patch checks for NUD_VALID and returns NO_NEIGH if the neigh is
not valid.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230217004150.2980689-3-martin.lau@linux.dev

bpf: devmap: check XDP features in __xdp_enqueue routine

Check if the destination device implements ndo_xdp_xmit callback relying
on NETDEV_XDP_ACT_NDO_XMIT flags. Moreover, check if the destination device
supports XDP non-linear frame in __xdp_enqueue and is_valid_dst routines.
This patch allows to perform XDP_REDIRECT on non-linear XDP buffers.

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Co-developed-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/26a94c33520c0bfba021b3fbb2cb8c1e69bf53b8.1675245258.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Use ARG_CONST_SIZE_OR_ZERO for 3rd argument of bpf_tcp_raw_gen_syncookie_ipv{4,6}()

These functions already check that th_len < sizeof(*th), and
propagating the lower bound (th_len > 0) may be challenging
in complex code, e.g. as is the case with xdp_synproxy test on
s390x [1]. Switch to ARG_CONST_SIZE_OR_ZERO in order to make the
verifier accept code where it cannot prove that th_len > 0.

[1] https://lore.kernel.org/bpf/CAEf4Bzb3uiSHtUbgVWmkWuJ5Sw1UZd4c_iuS4QXtUkXmTTtXuQ@mail.gmail.com/

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230128000650.1516334-2-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Check the protocol of a sock to agree the calls to bpf_setsockopt().

Resolve an issue when calling sol_tcp_sockopt() on a socket with ktls
enabled. Prior to this patch, sol_tcp_sockopt() would only allow calls
if the function pointer of setsockopt of the socket was set to
tcp_setsockopt(). However, any socket with ktls enabled would have its
function pointer set to tls_setsockopt(). To resolve this issue, the
patch adds a check of the protocol of the linux socket and allows
bpf_setsockopt() to be called if ktls is initialized on the linux
socket. This ensures that calls to sol_tcp_sockopt() will succeed on
sockets with ktls enabled.

Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Link: https://lore.kernel.org/r/20230125201608.908230-2-kuifeng@meta.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Rename bpf_{prog,map}_is_dev_bound to is_offloaded

BPF offloading infra will be reused to implement
bound-but-not-offloaded bpf programs. Rename existing
helpers for clarity. No functional changes.

Cc: John Fastabend <john.fastabend@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230119221536.3349901-3-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

xdp: document xdp_do_flush() before napi_complete_done()

Document in the XDP_REDIRECT manual section that drivers must call
xdp_do_flush() before napi_complete_done(). The two reasons behind
this can be found following the links below.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com
Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Add ipip6 and ip6ip decap support for bpf_skb_adjust_room()

Add ipip6 and ip6ip decap support for bpf_skb_adjust_room().
Main use case is for using cls_bpf on ingress hook to decapsulate
IPv4 over IPv6 and IPv6 over IPv4 tunnel packets.

Add two new flags BPF_F_ADJ_ROOM_DECAP_L3_IPV{4,6} to indicate the
new IP header version after decapsulating the outer IP header.

Suggested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/b268ec7f0ff9431f4f43b1b40ab856ebb28cb4e1.1673574419.git.william.xuanziyang@huawei.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Remove the unnecessary insn buffer comparison

The variable 'insn' is initialized to 'insn_buf' without being changed, only
some helper macros are defined, so the insn buffer comparison is unnecessary.
Just remove it. This missed removal back in 2377b81de527 ("bpf: split shared
bpf_tcp_sock and bpf_sock_ops implementation").

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230108151258.96570-1-haiyue.wang@intel.com

bpf: Add flag BPF_F_NO_TUNNEL_KEY to bpf_skb_set_tunnel_key()

This patch allows to remove TUNNEL_KEY from the tunnel flags bitmap
when using bpf_skb_set_tunnel_key by providing a BPF_F_NO_TUNNEL_KEY
flag. On egress, the resulting tunnel header will not contain a tunnel
key if the protocol and implementation supports it.

At the moment bpf_tunnel_key wants a user to specify a numeric tunnel
key. This will wrap the inner packet into a tunnel header with the key
bit and value set accordingly. This is problematic when using a tunnel
protocol that supports optional tunnel keys and a receiving tunnel
device that is not expecting packets with the key bit set. The receiver
won't decapsulate and drop the packet.

RFC 2890 and RFC 2784 GRE tunnels are examples where this flag is
useful. It allows for generating packets, that can be decapsulated by
a GRE tunnel device not operating in collect metadata mode or not
expecting the key bit set.

Signed-off-by: Christian Ehrig <cehrig@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221218051734.31411-1-cehrig@cloudflare.com

bpf: pull before calling skb_postpull_rcsum()

Anand hit a BUG() when pulling off headers on egress to a SW tunnel.
We get to skb_checksum_help() with an invalid checksum offset
(commit d7ea0d9df2a6 ("net: remove two BUG() from skb_checksum_help()")
converted those BUGs to WARN_ONs()).
He points out oddness in how skb_postpull_rcsum() gets used.
Indeed looks like we should pull before "postpull", otherwise
the CHECKSUM_PARTIAL fixup from skb_postpull_rcsum() will not
be able to do its job:

if (skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_start_offset(skb) < 0)
skb->ip_summed = CHECKSUM_NONE;

Reported-by: Anand Parthasarathy <anpartha@meta.com>
Fixes: 6578171a7ff0 ("bpf: add bpf_skb_change_proto helper")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221220004701.402165-1-kuba@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

xfrm: interface: Add unstable helpers for setting/getting XFRM metadata from TC-BPF

This change adds xfrm metadata helpers using the unstable kfunc call
interface for the TC-BPF hooks. This allows steering traffic towards
different IPsec connections based on logic implemented in bpf programs.

This object is built based on the availability of BTF debug info.

When setting the xfrm metadata, percpu metadata dsts are used in order
to avoid allocating a metadata dst per packet.

In order to guarantee safe module unload, the percpu dsts are allocated
on first use and never freed. The percpu pointer is stored in
net/core/filter.c so that it can be reused on module reload.

The metadata percpu dsts take ownership of the original skb dsts so
that they may be used as part of the xfrm transmission logic - e.g.
for MTU calculations.

Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Link: https://lore.kernel.org/r/20221203084659.1837829-3-eyal.birger@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf: Add dummy type reference to nf_conn___init to fix type deduplication

The bpf_ct_set_nat_info() kfunc is defined in the nf_nat.ko module, and
takes as a parameter the nf_conn___init struct, which is allocated through
the bpf_xdp_ct_alloc() helper defined in the nf_conntrack.ko module.
However, because kernel modules can't deduplicate BTF types between each
other, and the nf_conn___init struct is not referenced anywhere in vmlinux
BTF, this leads to two distinct BTF IDs for the same type (one in each
module). This confuses the verifier, as described here:

https://lore.kernel.org/all/87leoh372s.fsf@toke.dk/

As a workaround, add an explicit BTF_TYPE_EMIT for the type in
net/filter.c, so the type definition gets included in vmlinux BTF. This
way, both modules can refer to the same type ID (as they both build on top
of vmlinux BTF), and the verifier is no longer confused.

v2:

- Use BTF_TYPE_EMIT (which is a statement so it has to be inside a function
definition; use xdp_func_proto() for this, since this is mostly
xdp-related).

Fixes: 820dc0523e05 ("net: netfilter: move bpf_ct_set_nat_info kfunc in nf_nat_bpf.c")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20221201123939.696558-1-toke@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Move skb->len == 0 checks into __bpf_redirect

To avoid potentially breaking existing users.

Both mac/no-mac cases have to be amended; mac_header >= network_header
is not enough (verified with a new test, see next patch).

Fixes: fd1894224407 ("bpf: Don't redirect packets with invalid pkt_len")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221121180340.1983627-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf, docs: DEVMAPs and XDP_REDIRECT

Add documentation for BPF_MAP_TYPE_DEVMAP and BPF_MAP_TYPE_DEVMAP_HASH
including kernel version introduced, usage and examples.

Add documentation that describes XDP_REDIRECT.

Signed-off-by: Maryam Tahhan <mtahhan@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221115144921.165483-1-mtahhan@redhat.com

udp: Access &udp_table via net.

We will soon introduce an optional per-netns hash table
for UDP.

This means we cannot use udp_table directly in most places.

Instead, access it via net->ipv4.udp_table.

The access will be valid only while initialising udp_table
itself and creating/destroying each netns.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Expand map key argument of bpf_redirect_map to u64

For queueing packets in XDP we want to add a new redirect map type with
support for 64-bit indexes. To prepare fore this, expand the width of the
'key' argument to the bpf_redirect_map() helper. Since BPF registers are
always 64-bit, this should be safe to do after the fact.

Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20221108140601.149971-3-toke@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Refactor btf_struct_access

Instead of having to pass multiple arguments that describe the register,
pass the bpf_reg_state into the btf_struct_access callback. Currently,
all call sites simply reuse the btf and btf_id of the reg they want to
check the access of. The only exception to this pattern is the callsite
in check_ptr_to_map_access, hence for that case create a dummy reg to
simulate PTR_TO_BTF_ID access.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221114191547.1694267-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net: remove skb->vlan_present

skb->vlan_present seems redundant.

We can instead derive it from this boolean expression:

vlan_present = skb->vlan_proto != 0 || skb->vlan_tci != 0

Add a new union, to access both fields in a single load/store
when possible.

union {
u32 vlan_all;
struct {
__be16 vlan_proto;
__u16 vlan_tci;
};
};

This allows following patch to remove a conditional test in GRO stack.

Note:
We move remcsum_offload to keep TC_AT_INGRESS_MASK
and SKB_MONO_DELIVERY_TIME_MASK unchanged.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: Add hwtstamp field for the sockops prog

The bpf-tc prog has already been able to access the
skb_hwtstamps(skb)->hwtstamp. This patch extends the same hwtstamp
access to the sockops prog.

In sockops, the skb is also available to the bpf prog during
the BPF_SOCK_OPS_PARSE_HDR_OPT_CB event. There is a use case
that the hwtstamp will be useful to the sockops prog to better
measure the one-way-delay when the sender has put the tx
timestamp in the tcp header option.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221107230420.4192307-2-martin.lau@linux.dev

bpf: make sure skb->len != 0 when redirecting to a tunneling device

syzkaller managed to trigger another case where skb->len == 0
when we enter __dev_queue_xmit:

WARNING: CPU: 0 PID: 2470 at include/linux/skbuff.h:2576 skb_assert_len include/linux/skbuff.h:2576 [inline]
WARNING: CPU: 0 PID: 2470 at include/linux/skbuff.h:2576 __dev_queue_xmit+0x2069/0x35e0 net/core/dev.c:4295

Call Trace:
dev_queue_xmit+0x17/0x20 net/core/dev.c:4406
__bpf_tx_skb net/core/filter.c:2115 [inline]
__bpf_redirect_no_mac net/core/filter.c:2140 [inline]
__bpf_redirect+0x5fb/0xda0 net/core/filter.c:2163
____bpf_clone_redirect net/core/filter.c:2447 [inline]
bpf_clone_redirect+0x247/0x390 net/core/filter.c:2419
bpf_prog_48159a89cb4a9a16+0x59/0x5e
bpf_dispatcher_nop_func include/linux/bpf.h:897 [inline]
__bpf_prog_run include/linux/filter.h:596 [inline]
bpf_prog_run include/linux/filter.h:603 [inline]
bpf_test_run+0x46c/0x890 net/bpf/test_run.c:402
bpf_prog_test_run_skb+0xbdc/0x14c0 net/bpf/test_run.c:1170
bpf_prog_test_run+0x345/0x3c0 kernel/bpf/syscall.c:3648
__sys_bpf+0x43a/0x6c0 kernel/bpf/syscall.c:5005
__do_sys_bpf kernel/bpf/syscall.c:5091 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5089 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5089
do_syscall_64+0x54/0x70 arch/x86/entry/common.c:48
entry_SYSCALL_64_after_hwframe+0x61/0xc6

The reproducer doesn't really reproduce outside of syzkaller
environment, so I'm taking a guess here. It looks like we
do generate correct ETH_HLEN-sized packet, but we redirect
the packet to the tunneling device. Before we do so, we
__skb_pull l2 header and arrive again at skb->len == 0.
Doesn't seem like we can do anything better than having
an explicit check after __skb_pull?

Cc: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot+f635e86ec3fa0a37e019@syzkaller.appspotmail.com
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221027225537.353077-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: tcp: Stop bpf_setsockopt(TCP_CONGESTION) in init ops to recur itself

When a bad bpf prog '.init' calls
bpf_setsockopt(TCP_CONGESTION, "itself"), it will trigger this loop:

.init => bpf_setsockopt(tcp_cc) => .init => bpf_setsockopt(tcp_cc) ...
... => .init => bpf_setsockopt(tcp_cc).

It was prevented by the prog->active counter before but the prog->active
detection cannot be used in struct_ops as explained in the earlier
patch of the set.

In this patch, the second bpf_setsockopt(tcp_cc) is not allowed
in order to break the loop. This is done by using a bit of
an existing 1 byte hole in tcp_sock to check if there is
on-going bpf_setsockopt(TCP_CONGESTION) in this tcp_sock.

Note that this essentially limits only the first '.init' can
call bpf_setsockopt(TCP_CONGESTION) to pick a fallback cc (eg. peer
does not support ECN) and the second '.init' cannot fallback to
another cc. This applies even the second
bpf_setsockopt(TCP_CONGESTION) will not cause a loop.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220929070407.965581-5-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Refactor bpf_setsockopt(TCP_CONGESTION) handling into another function

This patch moves the bpf_setsockopt(TCP_CONGESTION) logic into
another function. The next patch will add extra logic to avoid
recursion and this will make the latter patch easier to follow.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220929070407.965581-4-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Move the "cdg" tcp-cc check to the common sol_tcp_sockopt()

The check on the tcp-cc, "cdg", is done in the bpf_sk_setsockopt which is
used by the bpf_tcp_ca, bpf_lsm, cg_sockopt, and tcp_iter hooks.
However, it is not done for cg sock_ddr, cg sockops, and some of
the bpf_lsm_cgroup hooks.

The tcp-cc "cdg" should have very limited usage. This patch is to
move the "cdg" check to the common sol_tcp_sockopt() so that all
hooks have a consistent behavior. The motivation to make
this check consistent now is because the latter patch will
refactor the bpf_setsockopt(TCP_CONGESTION) into another function,
so it is better to take this chance to refactor this piece
also.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220929070407.965581-3-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Rename nfct_bsa to nfct_btf_struct_access

The former name was a little hard to guess.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/73adc72385c8b162391fbfb404f0b6d4c5cc55d7.1663683114.git.dxu@dxuuu.xyz
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tcp: Access &tcp_hashinfo via net.

We will soon introduce an optional per-netns ehash.

This means we cannot use tcp_hashinfo directly in most places.

Instead, access it via net->ipv4.tcp_death_row.hashinfo.

The access will be valid only while initialising tcp_hashinfo
itself and creating/destroying each netns.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: Add support for writing to nf_conn:mark

Support direct writes to nf_conn:mark from TC and XDP prog types. This
is useful when applications want to store per-connection metadata. This
is also particularly useful for applications that run both bpf and
iptables/nftables because the latter can trivially access this metadata.

One example use case would be if a bpf prog is responsible for advanced
packet classification and iptables/nftables is later used for routing
due to pre-existing/legacy code.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/ebca06dea366e3e7e861c12f375a548cc4c61108.1662568410.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_getsockopt(SOL_IPV6) to reuse do_ipv6_getsockopt()

This patch changes bpf_getsockopt(SOL_IPV6) to reuse
do_ipv6_getsockopt(). It removes the duplicated code from
bpf_getsockopt(SOL_IPV6).

This also makes bpf_getsockopt(SOL_IPV6) supporting the same
set of optnames as in bpf_setsockopt(SOL_IPV6). In particular,
this adds IPV6_AUTOFLOWLABEL support to bpf_getsockopt(SOL_IPV6).

ipv6 could be compiled as a module. Like how other code solved it
with stubs in ipv6_stubs.h, this patch adds the do_ipv6_getsockopt
to the ipv6_bpf_stub.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002931.2896218-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_getsockopt(SOL_IP) to reuse do_ip_getsockopt()

This patch changes bpf_getsockopt(SOL_IP) to reuse
do_ip_getsockopt() and remove the duplicated code.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002925.2895416-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_getsockopt(SOL_TCP) to reuse do_tcp_getsockopt()

This patch changes bpf_getsockopt(SOL_TCP) to reuse
do_tcp_getsockopt(). It removes the duplicated code from
bpf_getsockopt(SOL_TCP).

Before this patch, there were some optnames available to
bpf_setsockopt(SOL_TCP) but missing in bpf_getsockopt(SOL_TCP).
For example, TCP_NODELAY, TCP_MAXSEG, TCP_KEEPIDLE, TCP_KEEPINTVL,
and a few more. It surprises users from time to time. This patch
automatically closes this gap without duplicating more code.

bpf_getsockopt(TCP_SAVED_SYN) does not free the saved_syn,
so it stays in sol_tcp_sockopt().

For string name value like TCP_CONGESTION, bpf expects it
is always null terminated, so sol_tcp_sockopt() decrements
optlen by one before calling do_tcp_getsockopt() and
the 'if (optlen < saved_optlen) memset(..,0,..);'
in __bpf_getsockopt() will always do a null termination.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002918.2894511-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_getsockopt(SOL_SOCKET) to reuse sk_getsockopt()

This patch changes bpf_getsockopt(SOL_SOCKET) to reuse
sk_getsockopt(). It removes all duplicated code from
bpf_getsockopt(SOL_SOCKET).

Before this patch, there were some optnames available to
bpf_setsockopt(SOL_SOCKET) but missing in bpf_getsockopt(SOL_SOCKET).
It surprises users from time to time. For example, SO_REUSEADDR,
SO_KEEPALIVE, SO_RCVLOWAT, and SO_MAX_PACING_RATE. This patch
automatically closes this gap without duplicating more code.
The only exception is SO_BINDTODEVICE because it needs to acquire a
blocking lock. Thus, SO_BINDTODEVICE is not supported.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002912.2894040-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Embed kernel CONFIG check into the if statement in bpf_getsockopt

This patch moves the "#ifdef CONFIG_XXX" check into the "if/else"
statement itself. The change is done for the bpf_getsockopt()
function only. It will make the latter patches easier to follow
without the surrounding ifdef macro.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002906.2893572-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: net: Avoid sk_getsockopt() taking sk lock when called from bpf

Similar to the earlier commit that changed sk_setsockopt() to
use sockopt_{lock,release}_sock() such that it can avoid taking
lock when called from bpf. This patch also changes sk_getsockopt()
to use sockopt_{lock,release}_sock() such that a latter patch can
make bpf_getsockopt(SOL_SOCKET) to reuse sk_getsockopt().

Only sk_get_filter() requires this change and it is used by
the optname SO_GET_FILTER.

The '.getname' implementations in sock->ops->getname() is not
changed also since bpf does not always have the sk->sk_socket
pointer and cannot support SO_PEERNAME.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002809.2888981-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: net: Change sk_getsockopt() to take the sockptr_t argument

This patch changes sk_getsockopt() to take the sockptr_t argument
such that it can be used by bpf_getsockopt(SOL_SOCKET) in a
latter patch.

security_socket_getpeersec_stream() is not changed. It stays
with the __user ptr (optval.user and optlen.user) to avoid changes
to other security hooks. bpf_getsockopt(SOL_SOCKET) also does not
support SO_PEERSEC.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002802.2888419-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Support getting tunnel flags

Existing 'bpf_skb_get_tunnel_key' extracts various tunnel parameters
(id, ttl, tos, local and remote) but does not expose ip_tunnel_info's
tun_flags to the BPF program.

It makes sense to expose tun_flags to the BPF program.

Assume for example multiple GRE tunnels maintained on a single GRE
interface in collect_md mode. The program expects origins to initiate
over GRE, however different origins use different GRE characteristics
(e.g. some prefer to use GRE checksum, some do not; some pass a GRE key,
some do not, etc..).

A BPF program getting tun_flags can therefore remember the relevant
flags (e.g. TUNNEL_CSUM, TUNNEL_SEQ...) for each initiating remote. In
the reply path, the program can use 'bpf_skb_set_tunnel_key' in order
to correctly reply to the remote, using similar characteristics, based
on the stored tunnel flags.

Introduce BPF_F_TUNINFO_FLAGS flag for bpf_skb_get_tunnel_key. If
specified, 'bpf_tunnel_key->tunnel_flags' is set with the tun_flags.

Decided to use the existing unused 'tunnel_ext' as the storage for the
'tunnel_flags' in order to avoid changing bpf_tunnel_key's layout.

Also, the following has been considered during the design:

1. Convert the "interesting" internal TUNNEL_xxx flags back to BPF_F_yyy
and place into the new 'tunnel_flags' field. This has 2 drawbacks:

- The BPF_F_yyy flags are from *set_tunnel_key* enumeration space,
e.g. BPF_F_ZERO_CSUM_TX. It is awkward that it is "returned" into
tunnel_flags from a *get_tunnel_key* call.
- Not all "interesting" TUNNEL_xxx flags can be mapped to existing
BPF_F_yyy flags, and it doesn't make sense to create new BPF_F_yyy
flags just for purposes of the returned tunnel_flags.

2. Place key.tun_flags into 'tunnel_flags' but mask them, keeping only
"interesting" flags. That's ok, but the drawback is that what's
"interesting" for my usecase might be limiting for other usecases.

Therefore I decided to expose what's in key.tun_flags *as is*, which seems
most flexible. The BPF user can just choose to ignore bits he's not
interested in. The TUNNEL_xxx are also UAPI, so no harm exposing them
back in the get_tunnel_key call.

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220831144010.174110-1-shmulik.ladkani@gmail.com

bpf: Use cgroup_{common,current}_func_proto in more hooks

The following hooks are per-cgroup hooks but they are not
using cgroup_{common,current}_func_proto, fix it:

* BPF_PROG_TYPE_CGROUP_SKB (cg_skb)
* BPF_PROG_TYPE_CGROUP_SOCK_ADDR (cg_sock_addr)
* BPF_PROG_TYPE_CGROUP_SOCK (cg_sock)
* BPF_PROG_TYPE_LSM+BPF_LSM_CGROUP

Also:

* move common func_proto's into cgroup func_proto handlers
* make sure bpf_{g,s}et_retval are not accessible from recvmsg,
getpeername and getsockname (return/errno is ignored in these
places)
* as a side effect, expose get_current_pid_tgid, get_current_comm_proto,
get_current_ancestor_cgroup_id, get_cgroup_classid to more cgroup
hooks

Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220823222555.523590-3-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add a few optnames to bpf_setsockopt

This patch adds a few optnames for bpf_setsockopt:
SO_REUSEADDR, IPV6_AUTOFLOWLABEL, TCP_MAXSEG, TCP_NODELAY,
and TCP_THIN_LINEAR_TIMEOUTS.

Thanks to the previous patches of this set, all additions can reuse
the sk_setsockopt(), do_ipv6_setsockopt(), and do_tcp_setsockopt().
The only change here is to allow them in bpf_setsockopt.

The bpf prog has been able to read all members of a sk by
using PTR_TO_BTF_ID of a sk. The optname additions here can also be
read by the same approach. Meaning there is a way to read
the values back.

These optnames can also be added to bpf_getsockopt() later with
another patch set that makes the bpf_getsockopt() to reuse
the sock_getsockopt(), tcp_getsockopt(), and ip[v6]_getsockopt().
Thus, this patch does not add more duplicated code to
bpf_getsockopt() now.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061841.4181642-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_setsockopt(SOL_IPV6) to reuse do_ipv6_setsockopt()

After the prep work in the previous patches,
this patch removes the dup code from bpf_setsockopt(SOL_IPV6)
and reuses the implementation in do_ipv6_setsockopt().

ipv6 could be compiled as a module. Like how other code solved it
with stubs in ipv6_stubs.h, this patch adds the do_ipv6_setsockopt
to the ipv6_bpf_stub.

The current bpf_setsockopt(IPV6_TCLASS) does not take the
INET_ECN_MASK into the account for tcp. The
do_ipv6_setsockopt(IPV6_TCLASS) will handle it correctly.

The existing optname white-list is refactored into a new
function sol_ipv6_setsockopt().

After this last SOL_IPV6 dup code removal, the __bpf_setsockopt()
is simplified enough that the extra "{ }" around the if statement
can be removed.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061834.4181198-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_setsockopt(SOL_IP) to reuse do_ip_setsockopt()

After the prep work in the previous patches,
this patch removes the dup code from bpf_setsockopt(SOL_IP)
and reuses the implementation in do_ip_setsockopt().

The existing optname white-list is refactored into a new
function sol_ip_setsockopt().

NOTE,
the current bpf_setsockopt(IP_TOS) is quite different from the
the do_ip_setsockopt(IP_TOS). For example, it does not take
the INET_ECN_MASK into the account for tcp and also does not adjust
sk->sk_priority. It looks like the current bpf_setsockopt(IP_TOS)
was referencing the IPV6_TCLASS implementation instead of IP_TOS.
This patch tries to rectify that by using the do_ip_setsockopt(IP_TOS).
While this is a behavior change, the do_ip_setsockopt(IP_TOS) behavior
is arguably what the user is expecting. At least, the INET_ECN_MASK bits
should be masked out for tcp.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061826.4180990-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_setsockopt(SOL_TCP) to reuse do_tcp_setsockopt()

After the prep work in the previous patches,
this patch removes all the dup code from bpf_setsockopt(SOL_TCP)
and reuses the do_tcp_setsockopt().

The existing optname white-list is refactored into a new
function sol_tcp_setsockopt(). The sol_tcp_setsockopt()
also calls the bpf_sol_tcp_setsockopt() to handle
the TCP_BPF_XXX specific optnames.

bpf_setsockopt(TCP_SAVE_SYN) now also allows a value 2 to
save the eth header also and it comes for free from
do_tcp_setsockopt().

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061819.4180146-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Refactor bpf specific tcp optnames to a new function

The patch moves all bpf specific tcp optnames (TCP_BPF_XXX)
to a new function bpf_sol_tcp_setsockopt(). This will make
the next patch easier to follow.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061812.4179645-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Change bpf_setsockopt(SOL_SOCKET) to reuse sk_setsockopt()

After the prep work in the previous patches,
this patch removes most of the dup code from bpf_setsockopt(SOL_SOCKET)
and reuses them from sk_setsockopt().

The sock ptr test is added to the SO_RCVLOWAT because
the sk->sk_socket could be NULL in some of the bpf hooks.

The existing optname white-list is refactored into a new
function sol_socket_setsockopt().

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061804.4178920-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Embed kernel CONFIG check into the if statement in bpf_setsockopt

This patch moves the "#ifdef CONFIG_XXX" check into the "if/else"
statement itself. The change is done for the bpf_setsockopt()
function only. It will make the latter patches easier to follow
without the surrounding ifdef macro.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061758.4178374-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net: Fix data-races around sysctl_optmem_max.

While reading sysctl_optmem_max, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Fix data-races around sysctl_[rw]mem_(max|default).

While reading sysctl_[rw]mem_(max|default), they can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: bpf: Use the protocol's set_rcvlowat behavior if there is one

The commit d1361840f8c5 ("tcp: fix SO_RCVLOWAT and RCVBUF autotuning")
add one new (struct proto_ops)->set_rcvlowat method so that a protocol
can override the default setsockopt(SO_RCVLOWAT) behavior.

The prior bpf codes don't check and invoke the protos's set_rcvlowat,
now correct it.

Signed-off-by: Gao Feng <gfree.wind@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Fix bpf_xdp_pointer return pointer

For the case where offset + len == size, bpf_xdp_pointer should return a
valid pointer to the addr because that access is permitted. We should
only return NULL in the case where offset + len exceeds size.

Fixes: 3f364222d032 ("net: xdp: introduce bpf_xdp_pointer utility routine")
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/bpf/20220722220105.2065466-1-joannelkoong@gmail.com

bpf: Set flow flag to allow any source IP in bpf_tunnel_key

Commit 26101f5ab6bd ("bpf: Add source ip in "struct bpf_tunnel_key"")
added support for getting and setting the outer source IP of encapsulated
packets via the bpf_skb_{get,set}_tunnel_key BPF helper. This change
allows BPF programs to set any IP address as the source, including for
example the IP address of a container running on the same host.

In that last case, however, the encapsulated packets are dropped when
looking up the route because the source IP address isn't assigned to any
interface on the host. To avoid this, we need to set the
FLOWI_FLAG_ANYSRC flag.

Fixes: 26101f5ab6bd ("bpf: Add source ip in "struct bpf_tunnel_key"")
Signed-off-by: Paul Chaignon <paul@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/76873d384e21288abe5767551a0799ac93ec07fb.1658759380.git.paul@isovalent.com

bpf: Add endian modifiers to fix endian warnings

A couple of the syscalls which load values (bpf_skb_load_helper_16() and
bpf_skb_load_helper_32()) are using u16/u32 types which are triggering
warnings as they are then converted from big-endian to CPU-endian. Fix
these by making the types __be instead.

Fixes the following sparse warnings:

net/core/filter.c:246:32: warning: cast to restricted __be16
net/core/filter.c:246:32: warning: cast to restricted __be16
net/core/filter.c:246:32: warning: cast to restricted __be16
net/core/filter.c:246:32: warning: cast to restricted __be16
net/core/filter.c:273:32: warning: cast to restricted __be32
net/core/filter.c:273:32: warning: cast to restricted __be32
net/core/filter.c:273:32: warning: cast to restricted __be32
net/core/filter.c:273:32: warning: cast to restricted __be32
net/core/filter.c:273:32: warning: cast to restricted __be32
net/core/filter.c:273:32: warning: cast to restricted __be32

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220714105101.297304-1-ben.dooks@sifive.com

bpf: Omit superfluous address family check in __bpf_skc_lookup

family is only set to either AF_INET or AF_INET6 based on len. In all
other cases we return early. Thus the check against AF_UNSPEC can be
omitted.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220630082618.15649-1-tklauser@distanz.ch

bpf: expose bpf_{g,s}etsockopt to lsm cgroup

I don't see how to make it nice without introducing btf id lists
for the hooks where these helpers are allowed. Some LSM hooks
work on the locked sockets, some are triggering early and
don't grab any locks, so have two lists for now:

1. LSM hooks which trigger under socket lock - minority of the hooks,
but ideal case for us, we can expose existing BTF-based helpers
2. LSM hooks which trigger without socket lock, but they trigger
early in the socket creation path where it should be safe to
do setsockopt without any locks
3. The rest are prohibited. I'm thinking that this use-case might
be a good gateway to sleeping lsm cgroup hooks in the future.
We can either expose lock/unlock operations (and add tracking
to the verifier) or have another set of bpf_setsockopt
wrapper that grab the locks and might sleep.

Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-7-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Fix bpf_skc_lookup comment wrt. return type

The function no longer returns 'unsigned long' as of commit edbf8c01de5a
("bpf: add skc_lookup_tcp helper").

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220617152121.29617-1-tklauser@distanz.ch

bpf: Allow the new syncookie helpers to work with SKBs

This commit allows the new BPF helpers to work in SKB context (in TC
BPF programs): bpf_tcp_raw_{gen,check}_syncookie_ipv{4,6}.

Using these helpers in TC BPF programs is not recommended, because it's
unlikely that the BPF program will provide any substantional speedup
compared to regular SYN cookies or synproxy, after the SKB is already
created.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20220615134847.3753567-6-maximmi@nvidia.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add helpers to issue and check SYN cookies in XDP

The new helpers bpf_tcp_raw_{gen,check}_syncookie_ipv{4,6} allow an XDP
program to generate SYN cookies in response to TCP SYN packets and to
check those cookies upon receiving the first ACK packet (the final
packet of the TCP handshake).

Unlike bpf_tcp_{gen,check}_syncookie these new helpers don't need a
listening socket on the local machine, which allows to use them together
with synproxy to accelerate SYN cookie generation.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20220615134847.3753567-4-maximmi@nvidia.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tcp: Fix data-races around sysctl_tcp_syncookies.

While reading sysctl_tcp_syncookies, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: bpf: fix skb checksum in bpf_push_seg6_encap()

Both helper functions bpf_lwt_seg6_action() and bpf_lwt_push_encap() use
the bpf_push_seg6_encap() to encapsulate the packet in an IPv6 with Segment
Routing Header (SRH) or insert an SRH between the IPv6 header and the
payload.
To achieve this result, such helper functions rely on bpf_push_seg6_encap()
which, in turn, leverages seg6_do_srh_{encap,inline}() to perform the
required operation (i.e. encap/inline).

This patch removes the initialization of the IPv6 header payload length
from bpf_push_seg6_encap(), as it is now handled properly by
seg6_do_srh_{encap,inline}() to prevent corruption of the skb checksum.

Fixes: fe94cc290f53 ("bpf: Add IPv6 Segment Routing helpers")
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

bpf: Fix request_sock leak in sk lookup helpers

A customer reported a request_socket leak in a Calico cloud environment. We
found that a BPF program was doing a socket lookup with takes a refcnt on
the socket and that it was finding the request_socket but returning the parent
LISTEN socket via sk_to_full_sk() without decrementing the child request socket
1st, resulting in request_sock slab object leak. This patch retains the
existing behaviour of returning full socks to the caller but it also decrements
the child request_socket if one is present before doing so to prevent the leak.

Thanks to Curtis Taylor for all the help in diagnosing and testing this. And
thanks to Antoine Tenart for the reproducer and patch input.

v2 of this patch contains, refactor as per Daniel Borkmann's suggestions to
validate RCU flags on the listen socket so that it balances with bpf_sk_release()
and update comments as per Martin KaFai Lau's suggestion. One small change to
Daniels suggestion, put "sk = sk2" under "if (sk2 != sk)" to avoid an extra
instruction.

Fixes: f7355a6c0497 ("bpf: Check sk_fullsock() before returning from bpf_sk_lookup()")
Fixes: edbf8c01de5a ("bpf: add skc_lookup_tcp helper")
Co-developed-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Curtis Taylor <cutaylor-pub@yahoo.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/56d6f898-bde0-bb25-3427-12a330b29fb8@iogearbox.net
Link: https://lore.kernel.org/bpf/20220615011540.813025-1-jmaxwell37@gmail.com

bpf: Add bpf_skc_to_mptcp_sock_proto

This patch implements a new struct bpf_func_proto, named
bpf_skc_to_mptcp_sock_proto. Define a new bpf_id BTF_SOCK_TYPE_MPTCP,
and a new helper bpf_skc_to_mptcp_sock(), which invokes another new
helper bpf_mptcp_sock_from_subflow() in net/mptcp/bpf.c to get struct
mptcp_sock from a given subflow socket.

v2: Emit BTF type, add func_id checks in verifier.c and bpf_trace.c,
remove build check for CONFIG_BPF_JIT
v5: Drop EXPORT_SYMBOL (Martin)

Co-developed-by: Nicolas Rybowski <nicolas.rybowski@tessares.net>
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Nicolas Rybowski <nicolas.rybowski@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220519233016.105670-2-mathew.j.martineau@linux.intel.com

bpf: Add source ip in "struct bpf_tunnel_key"

Add tunnel source ip field in "struct bpf_tunnel_key". Add related code
to set and get tunnel source field.

Signed-off-by: Kaixi Fan <fankaixi.li@bytedance.com>
Link: https://lore.kernel.org/r/20220430074844.69214-2-fankaixi.li@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Tag argument to be released in bpf_func_proto

Add a new type flag for bpf_arg_type that when set tells verifier that
for a release function, that argument's register will be the one for
which meta.ref_obj_id will be set, and which will then be released
using release_reference. To capture the regno, introduce a new field
release_regno in bpf_call_arg_meta.

This would be required in the next patch, where we may either pass NULL
or a refcounted pointer as an argument to the release function
bpf_kptr_xchg. Just releasing only when meta.ref_obj_id is set is not
enough, as there is a case where the type of argument needed matches,
but the ref_obj_id is set to 0. Hence, we must enforce that whenever
meta.ref_obj_id is zero, the register that is to be released can only
be NULL for a release function.

Since we now indicate whether an argument is to be released in
bpf_func_proto itself, is_release_function helper has lost its utitlity,
hence refactor code to work without it, and just rely on
meta.release_regno to know when to release state for a ref_obj_id.
Still, the restriction of one release argument and only one ref_obj_id
passed to BPF helper or kfunc remains. This may be lifted in the future.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-3-memxor@gmail.com

ipv6: Use ipv6_only_sock() helper in condition.

This patch replaces some sk_ipv6only tests with ipv6_only_sock().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Enlarge offset check value to INT_MAX in bpf_skb_{load,store}_bytes

The data length of skb frags + frag_list may be greater than 0xffff, and
skb_header_pointer can not handle negative offset. So, here INT_MAX is used
to check the validity of offset. Add the same change to the related function
skb_store_bytes.

Fixes: 05c74e5e53f6 ("bpf: add bpf_skb_load_bytes helper")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220416105801.88708-2-liujian56@huawei.com

tcp: add accessors to read/set tp->snd_cwnd

We had various bugs over the years with code
breaking the assumption that tp->snd_cwnd is greater
than zero.

Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added
in commit 8b8a321ff72c ("tcp: fix zero cwnd in tcp_cwnd_reduction")
can trigger, and without a repro we would have to spend
considerable time finding the bug.

Instead of complaining too late, we want to catch where
and when tp->snd_cwnd is set to an illegal value.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: Support dual-stack sockets in bpf_tcp_check_syncookie

bpf_tcp_gen_syncookie looks at the IP version in the IP header and
validates the address family of the socket. It supports IPv4 packets in
AF_INET6 dual-stack sockets.

On the other hand, bpf_tcp_check_syncookie looks only at the address
family of the socket, ignoring the real IP version in headers, and
validates only the packet size. This implementation has some drawbacks:

1. Packets are not validated properly, allowing a BPF program to trick
bpf_tcp_check_syncookie into handling an IPv6 packet on an IPv4
socket.

2. Dual-stack sockets fail the checks on IPv4 packets. IPv4 clients end
up receiving a SYNACK with the cookie, but the following ACK gets
dropped.

This patch fixes these issues by changing the checks in
bpf_tcp_check_syncookie to match the ones in bpf_tcp_gen_syncookie. IP
version from the header is taken into account, and it is validated
properly with address family.

Fixes: 399040847084 ("bpf: add helper to check for a valid SYN cookie")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Acked-by: Arthur Fabre <afabre@cloudflare.com>
Link: https://lore.kernel.org/bpf/20220406124113.2795730-1-maximmi@nvidia.com

bpf: Treat bpf_sk_lookup remote_port as a 2-byte field

In commit 9a69e2b385f4 ("bpf: Make remote_port field in struct
bpf_sk_lookup 16-bit wide") the remote_port field has been split up and
re-declared from u32 to be16.

However, the accompanying changes to the context access converter have not
been well thought through when it comes big-endian platforms.

Today 2-byte wide loads from offsetof(struct bpf_sk_lookup, remote_port)
are handled as narrow loads from a 4-byte wide field.

This by itself is not enough to create a problem, but when we combine

1. 32-bit wide access to ->remote_port backed by a 16-wide wide load, with
2. inherent difference between litte- and big-endian in how narrow loads
need have to be handled (see bpf_ctx_narrow_access_offset),

we get inconsistent results for a 2-byte loads from &ctx->remote_port on LE
and BE architectures. This in turn makes BPF C code for the common case of
2-byte load from ctx->remote_port not portable.

To rectify it, inform the context access converter that remote_port is
2-byte wide field, and only 1-byte loads need to be treated as narrow
loads.

At the same time, we special-case the 4-byte load from &ctx->remote_port to
continue handling it the same way as do today, in order to keep the
existing BPF programs working.

Fixes: 9a69e2b385f4 ("bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide")
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220319183356.233666-2-jakub@cloudflare.com

bpf: Remove BPF_SKB_DELIVERY_TIME_NONE and rename s/delivery_time_/tstamp_/

This patch is to simplify the uapi bpf.h regarding to the tstamp type
and use a similar way as the kernel to describe the value stored
in __sk_buff->tstamp.

My earlier thought was to avoid describing the semantic and
clock base for the rcv timestamp until there is more clarity
on the use case, so the __sk_buff->delivery_time_type naming instead
of __sk_buff->tstamp_type.

With some thoughts, it can reuse the UNSPEC naming. This patch first
removes BPF_SKB_DELIVERY_TIME_NONE and also

rename BPF_SKB_DELIVERY_TIME_UNSPEC to BPF_SKB_TSTAMP_UNSPEC
and BPF_SKB_DELIVERY_TIME_MONO to BPF_SKB_TSTAMP_DELIVERY_MONO.

The semantic of BPF_SKB_TSTAMP_DELIVERY_MONO is the same:
__sk_buff->tstamp has delivery time in mono clock base.

BPF_SKB_TSTAMP_UNSPEC means __sk_buff->tstamp has the (rcv)
tstamp at ingress and the delivery time at egress. At egress,
the clock base could be found from skb->sk->sk_clockid.
__sk_buff->tstamp == 0 naturally means NONE, so NONE is not needed.

With BPF_SKB_TSTAMP_UNSPEC for the rcv tstamp at ingress,
the __sk_buff->delivery_time_type is also renamed to __sk_buff->tstamp_type
which was also suggested in the earlier discussion:
https://lore.kernel.org/bpf/b181acbe-caf8-502d-4b7b-7d96b9fc5d55@iogearbox.net/

The above will then make __sk_buff->tstamp and __sk_buff->tstamp_type
the same as its kernel skb->tstamp and skb->mono_delivery_time
counter part.

The internal kernel function bpf_skb_convert_dtime_type_read() is then
renamed to bpf_skb_convert_tstamp_type_read() and it can be simplified
with the BPF_SKB_DELIVERY_TIME_NONE gone. A BPF_ALU32_IMM(BPF_AND)
insn is also saved by using BPF_JMP32_IMM(BPF_JSET).

The bpf helper bpf_skb_set_delivery_time() is also renamed to
bpf_skb_set_tstamp(). The arg name is changed from dtime
to tstamp also. It only allows setting tstamp 0 for
BPF_SKB_TSTAMP_UNSPEC and it could be relaxed later
if there is use case to change mono delivery time to
non mono.

prog->delivery_time_access is also renamed to prog->tstamp_type_access.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220309090509.3712315-1-kafai@fb.com

bpf: Simplify insn rewrite on BPF_WRITE __sk_buff->tstamp

BPF_JMP32_IMM(BPF_JSET) is used to save a BPF_ALU32_IMM(BPF_AND).

The skb->tc_at_ingress and skb->mono_delivery_time are at the same
offset, so only one BPF_LDX_MEM(BPF_B) is needed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220309090502.3711982-1-kafai@fb.com

bpf: Simplify insn rewrite on BPF_READ __sk_buff->tstamp

The skb->tc_at_ingress and skb->mono_delivery_time are at the same
byte offset. Thus, only one BPF_LDX_MEM(BPF_B) is needed
and both bits can be tested together.

/* BPF_READ: a = __sk_buff->tstamp */
if (skb->tc_at_ingress && skb->mono_delivery_time)
a = 0;
else
a = skb->tstamp;

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220309090456.3711530-1-kafai@fb.com

bpf: net: Remove TC_AT_INGRESS_OFFSET and SKB_MONO_DELIVERY_TIME_OFFSET macro

This patch removes the TC_AT_INGRESS_OFFSET and
SKB_MONO_DELIVERY_TIME_OFFSET macros. Instead, PKT_VLAN_PRESENT_OFFSET
is used because all of them are at the same offset. Comment is added to
make it clear that changing the position of tc_at_ingress or
mono_delivery_time will require to adjust the defined macros.

The earlier discussion can be found here:
https://lore.kernel.org/bpf/419d994e-ff61-7c11-0ec7-11fefcb0186e@iogearbox.net/

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220309090450.3710955-1-kafai@fb.com

bpf: Add __sk_buff->delivery_time_type and bpf_skb_set_skb_delivery_time()

* __sk_buff->delivery_time_type:
This patch adds __sk_buff->delivery_time_type. It tells if the
delivery_time is stored in __sk_buff->tstamp or not.

It will be most useful for ingress to tell if the __sk_buff->tstamp
has the (rcv) timestamp or delivery_time. If delivery_time_type
is 0 (BPF_SKB_DELIVERY_TIME_NONE), it has the (rcv) timestamp.

Two non-zero types are defined for the delivery_time_type,
BPF_SKB_DELIVERY_TIME_MONO and BPF_SKB_DELIVERY_TIME_UNSPEC. For UNSPEC,
it can only happen in egress because only mono delivery_time can be
forwarded to ingress now. The clock of UNSPEC delivery_time
can be deduced from the skb->sk->sk_clockid which is how
the sch_etf doing it also.

* Provide forwarded delivery_time to tc-bpf@ingress:
With the help of the new delivery_time_type, the tc-bpf has a way
to tell if the __sk_buff->tstamp has the (rcv) timestamp or
the delivery_time. During bpf load time, the verifier will learn if
the bpf prog has accessed the new __sk_buff->delivery_time_type.
If it does, it means the tc-bpf@ingress is expecting the
skb->tstamp could have the delivery_time. The kernel will then
read the skb->tstamp as-is during bpf insn rewrite without
checking the skb->mono_delivery_time. This is done by adding a
new prog->delivery_time_access bit. The same goes for
writing skb->tstamp.

* bpf_skb_set_delivery_time():
The bpf_skb_set_delivery_time() helper is added to allow setting both
delivery_time and the delivery_time_type at the same time. If the
tc-bpf does not need to change the delivery_time_type, it can directly
write to the __sk_buff->tstamp as the existing tc-bpf has already been
doing. It will be most useful at ingress to change the
__sk_buff->tstamp from the (rcv) timestamp to
a mono delivery_time and then bpf_redirect_*().

bpf only has mono clock helper (bpf_ktime_get_ns), and
the current known use case is the mono EDT for fq, and
only mono delivery time can be kept during forward now,
so bpf_skb_set_delivery_time() only supports setting
BPF_SKB_DELIVERY_TIME_MONO. It can be extended later when use cases
come up and the forwarding path also supports other clock bases.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Keep the (rcv) timestamp behavior for the existing tc-bpf@ingress

The current tc-bpf@ingress reads and writes the __sk_buff->tstamp
as a (rcv) timestamp which currently could either be 0 (not available)
or ktime_get_real(). This patch is to backward compatible with the
(rcv) timestamp expectation at ingress. If the skb->tstamp has
the delivery_time, the bpf insn rewrite will read 0 for tc-bpf
running at ingress as it is not available. When writing at ingress,
it will also clear the skb->mono_delivery_time bit.

/* BPF_READ: a = __sk_buff->tstamp */
if (!skb->tc_at_ingress || !skb->mono_delivery_time)
a = skb->tstamp;
else
a = 0

/* BPF_WRITE: __sk_buff->tstamp = a */
if (skb->tc_at_ingress)
skb->mono_delivery_time = 0;
skb->tstamp = a;

[ A note on the BPF_CGROUP_INET_INGRESS which can also access
skb->tstamp. At that point, the skb is delivered locally
and skb_clear_delivery_time() has already been done,
so the skb->tstamp will only have the (rcv) timestamp. ]

If the tc-bpf@egress writes 0 to skb->tstamp, the skb->mono_delivery_time
has to be cleared also. It could be done together during
convert_ctx_access(). However, the latter patch will also expose
the skb->mono_delivery_time bit as __sk_buff->delivery_time_type.
Changing the delivery_time_type in the background may surprise
the user, e.g. the 2nd read on __sk_buff->delivery_time_type
may need a READ_ONCE() to avoid compiler optimization. Thus,
in expecting the needs in the latter patch, this patch does a
check on !skb->tstamp after running the tc-bpf and clears the
skb->mono_delivery_time bit if needed. The earlier discussion
on v4 [0].

The bpf insn rewrite requires the skb's mono_delivery_time bit and
tc_at_ingress bit. They are moved up in sk_buff so that bpf rewrite
can be done at a fixed offset. tc_skip_classify is moved together with
tc_at_ingress. To get one bit for mono_delivery_time, csum_not_inet is
moved down and this bit is currently used by sctp.

[0]: https://lore.kernel.org/bpf/20220217015043.khqwqklx45c4m4se@kafai-mbp.dhcp.thefacebook.com/

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Add skb_clear_tstamp() to keep the mono delivery_time

Right now, skb->tstamp is reset to 0 whenever the skb is forwarded.

If skb->tstamp has the mono delivery_time, clearing it can hurt
the performance when it finally transmits out to fq@phy-dev.

The earlier patch added a skb->mono_delivery_time bit to
flag the skb->tstamp carrying the mono delivery_time.

This patch adds skb_clear_tstamp() helper which keeps
the mono delivery_time and clears everything else.

The delivery_time clearing will be postponed until the stack knows the
skb will be delivered locally. It will be done in a latter patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide

remote_port is another case of a BPF context field documented as a 32-bit
value in network byte order for which the BPF context access converter
generates a load of a zero-padded 16-bit integer in network byte order.

First such case was dst_port in bpf_sock which got addressed in commit
4421a582718a ("bpf: Make dst_port field in struct bpf_sock 16-bit wide").

Loading 4-bytes from the remote_port offset and converting the value with
bpf_ntohl() leads to surprising results, as the expected value is shifted
by 16 bits.

Reduce the confusion by splitting the field in two - a 16-bit field holding
a big-endian integer, and a 16-bit zero-padding anonymous field that
follows it.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220209184333.654927-2-jakub@cloudflare.com

skmsg: convert struct sk_msg_sg::copy to a bitmap

We have plans for increasing MAX_SKB_FRAGS, but sk_msg_sg::copy
is currently an unsigned long, limiting MAX_SKB_FRAGS to 30 on 32bit arches.

Convert it to a bitmap, as Jakub suggested.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Make dst_port field in struct bpf_sock 16-bit wide

Menglong Dong reports that the documentation for the dst_port field in
struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the
field is a zero-padded 16-bit integer in network byte order. The value
appears to the BPF user as if laid out in memory as so:

offsetof(struct bpf_sock, dst_port) + 0 <port MSB>
+ 8 <port LSB>
+16 0x00
+24 0x00

32-, 16-, and 8-bit wide loads from the field are all allowed, but only if
the offset into the field is 0.

32-bit wide loads from dst_port are especially confusing. The loaded value,
after converting to host byte order with bpf_ntohl(dst_port), contains the
port number in the upper 16-bits.

Remove the confusion by splitting the field into two 16-bit fields. For
backward compatibility, allow 32-bit wide loads from offsetof(struct
bpf_sock, dst_port).

While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port.

Reported-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/r/20220130115518.213259-2-jakub@cloudflare.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Add SO_TXREHASH setsockopt

Add bpf socket option to override rehash behaviour from userspace or from bpf.

Signed-off-by: Akhmat Karakotov <hmukos@yandex-team.ru>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xdp: disable XDP_REDIRECT for xdp frags

XDP_REDIRECT is not fully supported yet for xdp frags since not
all XDP capable drivers can map non-linear xdp_frame in ndo_xdp_xmit
so disable it for the moment.

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/0da25e117d0e2673f5d0ce6503393c55c6fb1be9.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net: xdp: introduce bpf_xdp_pointer utility routine

Similar to skb_header_pointer, introduce bpf_xdp_pointer utility routine
to return a pointer to a given position in the xdp_buff if the requested
area (offset + len) is contained in a contiguous memory area otherwise it
will be copied in a bounce buffer provided by the caller.
Similar to the tc counterpart, introduce the two following xdp helpers:
- bpf_xdp_load_bytes
- bpf_xdp_store_bytes

Reviewed-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/ab285c1efdd5b7a9d361348b1e7d3ef49f6382b3.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: add frags support to xdp copy helpers

This patch adds support for frags for the following helpers:
- bpf_xdp_output()
- bpf_perf_event_output()

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/340b4a99cdc24337b40eaf8bb597f9f9e7b0373e.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: add frags support to the bpf_xdp_adjust_tail() API

This change adds support for tail growing and shrinking for XDP frags.

When called on a non-linear packet with a grow request, it will work
on the last fragment of the packet. So the maximum grow size is the
last fragments tailroom, i.e. no new buffer will be allocated.
A XDP frags capable driver is expected to set frag_size in xdp_rxq_info
data structure to notify the XDP core the fragment size.
frag_size set to 0 is interpreted by the XDP core as tail growing is
not allowed.
Introduce __xdp_rxq_info_reg utility routine to initialize frag_size field.

When shrinking, it will work from the last fragment, all the way down to
the base buffer depending on the shrinking size. It's important to mention
that once you shrink down the fragment(s) are freed, so you can not grow
again to the original size.

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Link: https://lore.kernel.org/r/eabda3485dda4f2f158b477729337327e609461d.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: introduce bpf_xdp_get_buff_len helper

Introduce bpf_xdp_get_buff_len helper in order to return the xdp buffer
total size (linear and paged area)

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/aac9ac3504c84026cf66a3c71b7c5ae89bc991be.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Remove check_kfunc_call callback and old kfunc BTF ID API

Completely remove the old code for check_kfunc_call to help it work
with modules, and also the callback itself.

The previous commit adds infrastructure to register all sets and put
them in vmlinux or module BTF, and concatenates all related sets
organized by the hook and the type. Once populated, these sets remain
immutable for the lifetime of the struct btf.

Also, since we don't need the 'owner' module anywhere when doing
check_kfunc_call, drop the 'btf_modp' module parameter from
find_kfunc_desc_btf.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220114163953.1455836-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Do not try bpf_msg_push_data with len 0

If bpf_msg_push_data() is called with len 0 (as it happens during
selftests/bpf/test_sockmap), we do not need to do anything and can
return early.

Calling bpf_msg_push_data() with len 0 previously lead to a wrong ENOMEM
error: we later called get_order(copy + len); if len was 0, copy + len
was also often 0 and get_order() returned some undefined value (at the
moment 52). alloc_pages() caught that and failed, but then bpf_msg_push_data()
returned ENOMEM. This was wrong because we are most probably not out of
memory and actually do not need any additional memory.

Fixes: 6fff607e2f14b ("bpf: sk_msg program helper bpf_msg_push_data")
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/df69012695c7094ccb1943ca02b4920db3537466.1644421921.git.fmaurer@redhat.com

xdp: Add xdp_do_redirect_frame() for pre-computed xdp_frames

Add an xdp_do_redirect_frame() variant which supports pre-computed
xdp_frame structures. This will be used in bpf_prog_run() to avoid having
to write to the xdp_frame structure when the XDP program doesn't modify the
frame boundaries.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220103150812.87914-6-toke@redhat.com

xdp: Move conversion to xdp_frame out of map functions

All map redirect functions except XSK maps convert xdp_buff to xdp_frame
before enqueueing it. So move this conversion of out the map functions
and into xdp_do_redirect(). This removes a bit of duplicated code, but more
importantly it makes it possible to support caller-allocated xdp_frame
structures, which will be added in a subsequent commit.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220103150812.87914-5-toke@redhat.com

bpf: Add SO_RCVBUF/SO_SNDBUF in _bpf_getsockopt().

This patch exposes SO_RCVBUF/SO_SNDBUF through bpf_getsockopt().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220104013153.97906-3-kuniyu@amazon.co.jp

bpf: Fix SO_RCVBUF/SO_SNDBUF handling in _bpf_setsockopt().

The commit 4057765f2dee ("sock: consistent handling of extreme
SO_SNDBUF/SO_RCVBUF values") added a change to prevent underflow
in setsockopt() around SO_SNDBUF/SO_RCVBUF.

This patch adds the same change to _bpf_setsockopt().

Fixes: 4057765f2dee ("sock: consistent handling of extreme SO_SNDBUF/SO_RCVBUF values")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220104013153.97906-2-kuniyu@amazon.co.jp

bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.

Some helper functions may modify its arguments, for example,
bpf_d_path, bpf_get_stack etc. Previously, their argument types
were marked as ARG_PTR_TO_MEM, which is compatible with read-only
mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate,
but technically incorrect, to modify a read-only memory by passing
it into one of such helper functions.

This patch tags the bpf_args compatible with immutable memory with
MEM_RDONLY flag. The arguments that don't have this flag will be
only compatible with mutable memory types, preventing the helper
from modifying a read-only memory. The bpf_args that have
MEM_RDONLY are compatible with both mutable memory and immutable
memory.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211217003152.48334-9-haoluo@google.com

bpf: Let bpf_warn_invalid_xdp_action() report more info

In non trivial scenarios, the action id alone is not sufficient to
identify the program causing the warning. Before the previous patch,
the generated stack-trace pointed out at least the involved device
driver.

Let's additionally include the program name and id, and the relevant
device name.

If the user needs additional infos, he can fetch them via a kernel
probe, leveraging the arguments added here.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/ddb96bb975cbfddb1546cf5da60e77d5100b533c.1638189075.git.pabeni@redhat.com

bpf: Do not WARN in bpf_warn_invalid_xdp_action()

The WARN_ONCE() in bpf_warn_invalid_xdp_action() can be triggered by
any bugged program, and even attaching a correct program to a NIC
not supporting the given action.

The resulting splat, beyond polluting the logs, fouls automated tools:
e.g. a syzkaller reproducers using an XDP program returning an
unsupported action will never pass validation.

Replace the WARN_ONCE with a less intrusive pr_warn_once().

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/016ceec56e4817ebb2a9e35ce794d5c917df572c.1638189075.git.pabeni@redhat.com

bpf, docs: Prune all references to "internal BPF"

The eBPF name has completely taken over from eBPF in general usage for
the actual eBPF representation, or BPF for any general in-kernel use.
Prune all remaining references to "internal BPF".

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211119163215.971383-4-hch@lst.de

skbuff: Move conditional preprocessor directives out of struct sk_buff

In preparation for using the struct_group() macro in struct sk_buff,
move the conditional preprocessor directives out of the region of struct
sk_buff that will be enclosed by struct_group(). While GCC and Clang are
happy with conditional preprocessor directives here, sparse is not, even
under -Wno-directive-within-macro[1], as would be seen under a C=1 build:

net/core/filter.c: note: in included file (through include/linux/netlink.h, include/linux/sock_diag.h):
./include/linux/skbuff.h:820:1: warning: directive in macro's argument list
./include/linux/skbuff.h:822:1: warning: directive in macro's argument list
./include/linux/skbuff.h:846:1: warning: directive in macro's argument list
./include/linux/skbuff.h:848:1: warning: directive in macro's argument list

Additionally remove empty macro argument definitions and usage.

"objdump -d" shows no object code differences.

[1] https://www.spinics.net/lists/linux-sparse/msg10857.html

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Extend BTF_ID_LIST_GLOBAL with parameter for number of IDs

syzbot reported the following BUG w/o CONFIG_DEBUG_INFO_BTF

BUG: KASAN: global-out-of-bounds in task_iter_init+0x212/0x2e7 kernel/bpf/task_iter.c:661
Read of size 4 at addr ffffffff90297404 by task swapper/0/1

CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.15.0-syzkaller #0
Hardware name: ... Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xf/0x309 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
task_iter_init+0x212/0x2e7 kernel/bpf/task_iter.c:661
do_one_initcall+0x103/0x650 init/main.c:1295
do_initcall_level init/main.c:1368 [inline]
do_initcalls init/main.c:1384 [inline]
do_basic_setup init/main.c:1403 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1606
kernel_init+0x1a/0x1d0 init/main.c:1497
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

This is caused by hard-coded name[1] in BTF_ID_LIST_GLOBAL (w/o
CONFIG_DEBUG_INFO_BTF). Fix this by adding a parameter n to
BTF_ID_LIST_GLOBAL. This avoids ifdef CONFIG_DEBUG_INFO_BTF in btf.c and
filter.c.

Fixes: 7c7e3d31e785 ("bpf: Introduce helper bpf_find_vma")
Reported-by: syzbot+e0d81ec552a21d9071aa@syzkaller.appspotmail.com
Reported-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211112150243.1270987-2-songliubraving@fb.com

bpf: Add ingress_ifindex to bpf_sk_lookup

It may be helpful to have access to the ifindex during bpf socket
lookup. An example may be to scope certain socket lookup logic to
specific interfaces, i.e. an interface may be made exempt from custom
lookup code.

Add the ifindex of the arriving connection to the bpf_sk_lookup API.

Signed-off-by: Mark Pashmfouroush <markpash@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211110111016.5670-2-markpash@cloudflare.com

bpf: Forbid bpf_ktime_get_coarse_ns and bpf_timer_* in tracing progs

Use of bpf_ktime_get_coarse_ns() and bpf_timer_* helpers in tracing
progs may result in locking issues.

bpf_ktime_get_coarse_ns() uses ktime_get_coarse_ns() time accessor that
isn't safe for any context:
======================================================
WARNING: possible circular locking dependency detected
5.15.0-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/14877 is trying to acquire lock:
ffffffff8cb30008 (tk_core.seq.seqcount){----}-{0:0}, at: ktime_get_coarse_ts64+0x25/0x110 kernel/time/timekeeping.c:2255

but task is already holding lock:
ffffffff90dbf200 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_deactivate+0x61/0x400 lib/debugobjects.c:735

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&obj_hash[i].lock){-.-.}-{2:2}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
__debug_object_init+0xd9/0x1860 lib/debugobjects.c:569
debug_hrtimer_init kernel/time/hrtimer.c:414 [inline]
debug_init kernel/time/hrtimer.c:468 [inline]
hrtimer_init+0x20/0x40 kernel/time/hrtimer.c:1592
ntp_init_cmos_sync kernel/time/ntp.c:676 [inline]
ntp_init+0xa1/0xad kernel/time/ntp.c:1095
timekeeping_init+0x512/0x6bf kernel/time/timekeeping.c:1639
start_kernel+0x267/0x56e init/main.c:1030
secondary_startup_64_no_verify+0xb1/0xbb

-> #0 (tk_core.seq.seqcount){----}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3789
__lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625
seqcount_lockdep_reader_access+0xfe/0x230 include/linux/seqlock.h:103
ktime_get_coarse_ts64+0x25/0x110 kernel/time/timekeeping.c:2255
ktime_get_coarse include/linux/timekeeping.h:120 [inline]
ktime_get_coarse_ns include/linux/timekeeping.h:126 [inline]
____bpf_ktime_get_coarse_ns kernel/bpf/helpers.c:173 [inline]
bpf_ktime_get_coarse_ns+0x7e/0x130 kernel/bpf/helpers.c:171
bpf_prog_a99735ebafdda2f1+0x10/0xb50
bpf_dispatcher_nop_func include/linux/bpf.h:721 [inline]
__bpf_prog_run include/linux/filter.h:626 [inline]
bpf_prog_run include/linux/filter.h:633 [inline]
BPF_PROG_RUN_ARRAY include/linux/bpf.h:1294 [inline]
trace_call_bpf+0x2cf/0x5d0 kernel/trace/bpf_trace.c:127
perf_trace_run_bpf_submit+0x7b/0x1d0 kernel/events/core.c:9708
perf_trace_lock+0x37c/0x440 include/trace/events/lock.h:39
trace_lock_release+0x128/0x150 include/trace/events/lock.h:58
lock_release+0x82/0x810 kernel/locking/lockdep.c:5636
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline]
_raw_spin_unlock_irqrestore+0x75/0x130 kernel/locking/spinlock.c:194
debug_hrtimer_deactivate kernel/time/hrtimer.c:425 [inline]
debug_deactivate kernel/time/hrtimer.c:481 [inline]
__run_hrtimer kernel/time/hrtimer.c:1653 [inline]
__hrtimer_run_queues+0x2f9/0xa60 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
__sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103
sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1097
asm_sysvec_apic_timer_interrupt+0x12/0x20
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
try_to_wake_up+0x702/0xd20 kernel/sched/core.c:4118
wake_up_process kernel/sched/core.c:4200 [inline]
wake_up_q+0x9a/0xf0 kernel/sched/core.c:953
futex_wake+0x50f/0x5b0 kernel/futex/waitwake.c:184
do_futex+0x367/0x560 kernel/futex/syscalls.c:127
__do_sys_futex kernel/futex/syscalls.c:199 [inline]
__se_sys_futex+0x401/0x4b0 kernel/futex/syscalls.c:180
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

There is a possible deadlock with bpf_timer_* set of helpers:
hrtimer_start()
lock_base();
trace_hrtimer...()
perf_event()
bpf_run()
bpf_timer_start()
hrtimer_start()
lock_base() <- DEADLOCK

Forbid use of bpf_ktime_get_coarse_ns() and bpf_timer_* helpers in
BPF_PROG_TYPE_KPROBE, BPF_PROG_TYPE_TRACEPOINT, BPF_PROG_TYPE_PERF_EVENT
and BPF_PROG_TYPE_RAW_TRACEPOINT prog types.

Fixes: d05512618056 ("bpf: Add bpf_ktime_get_coarse_ns helper")
Fixes: b00628b1c7d5 ("bpf: Introduce bpf timers.")
Reported-by: syzbot+43fd005b5a1b4d10781e@syzkaller.appspotmail.com
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211113142227.566439-2-me@ubique.spb.ru

bpf, sockmap: sk_skb data_end access incorrect when src_reg = dst_reg

The current conversion of skb->data_end reads like this:

; data_end = (void*)(long)skb->data_end;
559: (79) r1 = *(u64 *)(r2 +200) ; r1 = skb->data
560: (61) r11 = *(u32 *)(r2 +112) ; r11 = skb->len
561: (0f) r1 += r11
562: (61) r11 = *(u32 *)(r2 +116)
563: (1f) r1 -= r11

But similar to the case in 84f44df664e9 ("bpf: sock_ops sk access may stomp
registers when dst_reg = src_reg"), the code will read an incorrect skb->len
when src == dst. In this case we end up generating this xlated code:

; data_end = (void*)(long)skb->data_end;
559: (79) r1 = *(u64 *)(r1 +200) ; r1 = skb->data
560: (61) r11 = *(u32 *)(r1 +112) ; r11 = (skb->data)->len
561: (0f) r1 += r11
562: (61) r11 = *(u32 *)(r1 +116)
563: (1f) r1 -= r11

... where line 560 is the reading 4B of (skb->data + 112) instead of the
intended skb->len Here the skb pointer in r1 gets set to skb->data and the
later deref for skb->len ends up following skb->data instead of skb.

This fixes the issue similarly to the patch mentioned above by creating an
additional temporary variable and using to store the register when dst_reg =
src_reg. We name the variable bpf_temp_reg and place it in the cb context for
sk_skb. Then we restore from the temp to ensure nothing is lost.

Fixes: 16137b09a66f2 ("bpf: Compute data_end dynamically with JIT code")
Signed-off-by: Jussi Maki <joamaki@gmail.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20211103204736.248403-6-john.fastabend@gmail.com

bpf: sockmap, strparser, and tls are reusing qdisc_skb_cb and colliding

Strparser is reusing the qdisc_skb_cb struct to stash the skb message handling
progress, e.g. offset and length of the skb. First this is poorly named and
inherits a struct from qdisc that doesn't reflect the actual usage of cb[] at
this layer.

But, more importantly strparser is using the following to access its metadata.

(struct _strp_msg *)((void *)skb->cb + offsetof(struct qdisc_skb_cb, data))

Where _strp_msg is defined as:

struct _strp_msg {
struct strp_msg strp; /* 0 8 */
int accum_len; /* 8 4 */

/* size: 12, cachelines: 1, members: 2 */
/* last cacheline: 12 bytes */
};

So we use 12 bytes of ->data[] in struct. However in BPF code running parser
and verdict the user has read capabilities into the data[] array as well. Its
not too problematic, but we should not be exposing internal state to BPF
program. If its really needed then we can use the probe_read() APIs which allow
reading kernel memory. And I don't believe cb[] layer poses any API breakage by
moving this around because programs can't depend on cb[] across layers.

In order to fix another issue with a ctx rewrite we need to stash a temp
variable somewhere. To make this work cleanly this patch builds a cb struct
for sk_skb types called sk_skb_cb struct. Then we can use this consistently
in the strparser, sockmap space. Additionally we can start allowing ->cb[]
write access after this.

Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jussi Maki <joamaki@gmail.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20211103204736.248403-5-john.fastabend@gmail.com

bpf, sockmap: Use stricter sk state checks in sk_lookup_assign

In order to fix an issue with sockets in TCP sockmap redirect cases we plan
to allow CLOSE state sockets to exist in the sockmap. However, the check in
bpf_sk_lookup_assign() currently only invalidates sockets in the
TCP_ESTABLISHED case relying on the checks on sockmap insert to ensure we
never SOCK_CLOSE state sockets in the map.

To prepare for this change we flip the logic in bpf_sk_lookup_assign() to
explicitly test for the accepted cases. Namely, a tcp socket in TCP_LISTEN
or a udp socket in TCP_CLOSE state. This also makes the code more resilent
to future changes.

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20211103204736.248403-2-john.fastabend@gmail.com

bpf: Add bpf_skc_to_unix_sock() helper

The helper is used in tracing programs to cast a socket
pointer to a unix_sock pointer.
The return value could be NULL if the casting is illegal.

Suggested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021134752.1223426-2-hengqi.chen@gmail.com

bpf: Add hardware timestamp field to __sk_buff

BPF programs may want to know hardware timestamps if NIC supports
such timestamping.

Expose this data as hwtstamp field of __sk_buff the same way as
gso_segs/gso_size. This field could be accessed from the same
programs as tstamp field, but it's read-only field. Explicit test
to deny access to padding data is added to bpf_skb_is_valid_access.

Also update BPF_PROG_TEST_RUN tests of the feature.

Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210909220409.8804-2-vfedorenko@novek.ru

bpf: tcp: Allow bpf-tcp-cc to call bpf_(get|set)sockopt

This patch allows the bpf-tcp-cc to call bpf_setsockopt. One use
case is to allow a bpf-tcp-cc switching to another cc during init().
For example, when the tcp flow is not ecn ready, the bpf_dctcp
can switch to another cc by calling setsockopt(TCP_CONGESTION).

During setsockopt(TCP_CONGESTION), the new tcp-cc's init() will be
called and this could cause a recursion but it is stopped by the
current trampoline's logic (in the prog->active counter).

While retiring a bpf-tcp-cc (e.g. in tcp_v[46]_destroy_sock()),
the tcp stack calls bpf-tcp-cc's release(). To avoid the retiring
bpf-tcp-cc making further changes to the sk, bpf_setsockopt is not
available to the bpf-tcp-cc's release(). This will avoid release()
making setsockopt() call that will potentially allocate new resources.

Although the bpf-tcp-cc already has a more powerful way to read tcp_sock
from the PTR_TO_BTF_ID, it is usually expected that bpf_getsockopt and
bpf_setsockopt are available together. Thus, bpf_getsockopt() is also
added to all tcp_congestion_ops except release().

When the old bpf-tcp-cc is calling setsockopt(TCP_CONGESTION)
to switch to a new cc, the old bpf-tcp-cc will be released by
bpf_struct_ops_put(). Thus, this patch also puts the bpf_struct_ops_map
after a rcu grace period because the trampoline's image cannot be freed
while the old bpf-tcp-cc is still running.

bpf-tcp-cc can only access icsk_ca_priv as SCALAR. All kernel's
tcp-cc is also accessing the icsk_ca_priv as SCALAR. The size
of icsk_ca_priv has already been raised a few times to avoid
extra kmalloc and memory referencing. The only exception is the
kernel's tcp_cdg.c that stores a kmalloc()-ed pointer in icsk_ca_priv.
To avoid the old bpf-tcp-cc accidentally overriding this tcp_cdg's pointer
value stored in icsk_ca_priv after switching and without over-complicating
the bpf's verifier for this one exception in tcp_cdg, this patch does not
allow switching to tcp_cdg. If there is a need, bpf_tcp_cdg can be
implemented and then use the bpf_sk_storage as the extended storage.

bpf_sk_setsockopt proto has only been recently added and used
in bpf-sockopt and bpf-iter-tcp, so impose the tcp_cdg limitation in the
same proto instead of adding a new proto specifically for bpf-tcp-cc.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210824173007.3976921-1-kafai@fb.com

bpf: Allow bpf_get_netns_cookie in BPF_PROG_TYPE_SK_MSG

We'd like to be able to identify netns from sk_msg hooks
to accelerate local process communication form different netns.

Signed-off-by: Xu Liu <liuxu623@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210820071712.52852-2-liuxu623@gmail.com

bpf: Allow bpf_get_netns_cookie in BPF_PROG_TYPE_SOCK_OPS

We'd like to be able to identify netns from sockops hooks to
accelerate local process communication form different netns.

Signed-off-by: Xu Liu <liuxu623@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818105820.91894-2-liuxu623@gmail.com

bpf: Refactor BPF_PROG_RUN into a function

Turn BPF_PROG_RUN into a proper always inlined function. No functional and
performance changes are intended, but it makes it much easier to understand
what's going on with how BPF programs are actually get executed. It's more
obvious what types and callbacks are expected. Also extra () around input
parameters can be dropped, as well as `__` variable prefixes intended to avoid
naming collisions, which makes the code simpler to read and write.

This refactoring also highlighted one extra issue. BPF_PROG_RUN is both
a macro and an enum value (BPF_PROG_RUN == BPF_PROG_TEST_RUN). Turning
BPF_PROG_RUN into a function causes naming conflict compilation error. So
rename BPF_PROG_RUN into lower-case bpf_prog_run(), similar to
bpf_prog_run_xdp(), bpf_prog_run_pin_on_cpu(), etc. All existing callers of
BPF_PROG_RUN, the macro, are switched to bpf_prog_run() explicitly.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-2-andrii@kernel.org

net, core: Add support for XDP redirection to slave device

This adds the ndo_xdp_get_xmit_slave hook for transforming XDP_TX
into XDP_REDIRECT after BPF program run when the ingress device
is a bond slave.

The dev_xdp_prog_count is exposed so that slave devices can be checked
for loaded XDP programs in order to avoid the situation where both
bond master and slave have programs loaded according to xdp_state.

Signed-off-by: Jussi Maki <joamaki@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Link: https://lore.kernel.org/bpf/20210731055738.16820-3-joamaki@gmail.com

bpf: use skb_expand_head in bpf_out_neigh_v4/6

Unlike skb_realloc_headroom, new helper skb_expand_head
does not allocate a new skb if possible.

Additionally this patch replaces commonly used dereferencing with variables.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: tcp: Support bpf_(get|set)sockopt in bpf tcp iter

This patch allows bpf tcp iter to call bpf_(get|set)sockopt.
To allow a specific bpf iter (tcp here) to call a set of helpers,
get_func_proto function pointer is added to bpf_iter_reg.
The bpf iter is a tracing prog which currently requires
CAP_PERFMON or CAP_SYS_ADMIN, so this patch does not
impose other capability checks for bpf_(get|set)sockopt.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200619.1036715-1-kafai@fb.com

bpf: cpumap: Implement generic cpumap

This change implements CPUMAP redirect support for generic XDP programs.
The idea is to reuse the cpu map entry's queue that is used to push
native xdp frames for redirecting skb to a different CPU. This will
match native XDP behavior (in that RPS is invoked again for packet
reinjected into networking stack).

To be able to determine whether the incoming skb is from the driver or
cpumap, we reuse skb->redirected bit that skips generic XDP processing
when it is set. To always make use of this, CONFIG_NET_REDIRECT guard on
it has been lifted and it is always available.

>From the redirect side, we add the skb to ptr_ring with its lowest bit
set to 1. This should be safe as skb is not 1-byte aligned. This allows
kthread to discern between xdp_frames and sk_buff. On consumption of the
ptr_ring item, the lowest bit is unset.

In the end, the skb is simply added to the list that kthread is anyway
going to maintain for xdp_frames converted to skb, and then received
again by using netif_receive_skb_list.

Bulking optimization for generic cpumap is left as an exercise for a
future patch for now.

Since cpumap entry progs are now supported, also remove check in
generic_xdp_install for the cpumap.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-4-memxor@gmail.com

bpf: Add function for XDP meta data length check

This commit prepares to use the XDP meta data length check in multiple
places by making it into a static inline function instead of a literal.

Co-developed-by: Cody Haas <chaas@riotgames.com>
Co-developed-by: Lisa Watanabe <lwatanabe@riotgames.com>
Signed-off-by: Cody Haas <chaas@riotgames.com>
Signed-off-by: Lisa Watanabe <lwatanabe@riotgames.com>
Signed-off-by: Zvi Effron <zeffron@riotgames.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210707221657.3985075-2-zeffron@riotgames.com

xdp: Add proper __rcu annotations to redirect map entries

XDP_REDIRECT works by a three-step process: the bpf_redirect() and
bpf_redirect_map() helpers will lookup the target of the redirect and store
it (along with some other metadata) in a per-CPU struct bpf_redirect_info.
Next, when the program returns the XDP_REDIRECT return code, the driver
will call xdp_do_redirect() which will use the information thus stored to
actually enqueue the frame into a bulk queue structure (that differs
slightly by map type, but shares the same principle). Finally, before
exiting its NAPI poll loop, the driver will call xdp_do_flush(), which will
flush all the different bulk queues, thus completing the redirect.

Pointers to the map entries will be kept around for this whole sequence of
steps, protected by RCU. However, there is no top-level rcu_read_lock() in
the core code; instead drivers add their own rcu_read_lock() around the XDP
portions of the code, but somewhat inconsistently as Martin discovered[0].
However, things still work because everything happens inside a single NAPI
poll sequence, which means it's between a pair of calls to
local_bh_disable()/local_bh_enable(). So Paul suggested[1] that we could
document this intention by using rcu_dereference_check() with
rcu_read_lock_bh_held() as a second parameter, thus allowing sparse and
lockdep to verify that everything is done correctly.

This patch does just that: we add an __rcu annotation to the map entry
pointers and remove the various comments explaining the NAPI poll assurance
strewn through devmap.c in favour of a longer explanation in filter.c. The
goal is to have one coherent documentation of the entire flow, and rely on
the RCU annotations as a "standard" way of communicating the flow in the
map code (which can additionally be understood by sparse and lockdep).

The RCU annotation replacements result in a fairly straight-forward
replacement where READ_ONCE() becomes rcu_dereference_check(), WRITE_ONCE()
becomes rcu_assign_pointer() and xchg() and cmpxchg() gets wrapped in the
proper constructs to cast the pointer back and forth between __rcu and
__kernel address space (for the benefit of sparse). The one complication is
that xskmap has a few constructions where double-pointers are passed back
and forth; these simply all gain __rcu annotations, and only the final
reference/dereference to the inner-most pointer gets changed.

With this, everything can be run through sparse without eliciting
complaints, and lockdep can verify correctness even without the use of
rcu_read_lock() in the drivers. Subsequent patches will clean these up from
the drivers.

[0] https://lore.kernel.org/bpf/20210415173551.7ma4slcbqeyiba2r@kafai-mbp.dhcp.thefacebook.com/
[1] https://lore.kernel.org/bpf/20210419165837.GA975577@paulmck-ThinkPad-P17-Gen-1/

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210624160609.292325-6-toke@redhat.com

bpf: Support all gso types in bpf_skb_change_proto()

Since we no longer modify gso_size, it is now theoretically
safe to not set SKB_GSO_DODGY and reset gso_segs to zero.

This also means the skb_is_gso_tcp() check should no longer
be necessary.

Unfortunately we cannot remove the skb_{decrease,increase}_gso_size()
helpers, as they are still used elsewhere:

bpf_skb_net_grow() without BPF_F_ADJ_ROOM_FIXED_GSO
bpf_skb_net_shrink() without BPF_F_ADJ_ROOM_FIXED_GSO
net/core/lwt_bpf.c's handle_gso_type()

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dongseok Yi <dseok.yi@samsung.com>
Cc: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/20210617000953.2787453-3-zenczykowski@gmail.com

bpf: Do not change gso_size during bpf_skb_change_proto()

This is technically a backwards incompatible change in behaviour, but I'm
going to argue that it is very unlikely to break things, and likely to fix
*far* more then it breaks.

In no particular order, various reasons follow:

(a) I've long had a bug assigned to myself to debug a super rare kernel crash
on Android Pixel phones which can (per stacktrace) be traced back to BPF clat
IPv6 to IPv4 protocol conversion causing some sort of ugly failure much later
on during transmit deep in the GSO engine, AFAICT precisely because of this
change to gso_size, though I've never been able to manually reproduce it. I
believe it may be related to the particular network offload support of attached
USB ethernet dongle being used for tethering off of an IPv6-only cellular
connection. The reason might be we end up with more segments than max permitted,
or with a GSO packet with only one segment... (either way we break some
assumption and hit a BUG_ON)

(b) There is no check that the gso_size is > 20 when reducing it by 20, so we
might end up with a negative (or underflowing) gso_size or a gso_size of 0.
This can't possibly be good. Indeed this is probably somehow exploitable (or
at least can result in a kernel crash) by delivering crafted packets and perhaps
triggering an infinite loop or a divide by zero... As a reminder: gso_size (MSS)
is related to MTU, but not directly derived from it: gso_size/MSS may be
significantly smaller then one would get by deriving from local MTU. And on
some NICs (which do loose MTU checking on receive, it may even potentially be
larger, for example my work pc with 1500 MTU can receive 1520 byte frames [and
sometimes does due to bugs in a vendor plat46 implementation]). Indeed even just
going from 21 to 1 is potentially problematic because it increases the number
of segments by a factor of 21 (think DoS, or some other crash due to too many
segments).

(c) It's always safe to not increase the gso_size, because it doesn't result in
the max packet size increasing. So the skb_increase_gso_size() call was always
unnecessary for correctness (and outright undesirable, see later). As such the
only part which is potentially dangerous (ie. could cause backwards compatibility
issues) is the removal of the skb_decrease_gso_size() call.

(d) If the packets are ultimately destined to the local device, then there is
absolutely no benefit to playing around with gso_size. It only matters if the
packets will egress the device. ie. we're either forwarding, or transmitting
from the device.

(e) This logic only triggers for packets which are GSO. It does not trigger for
skbs which are not GSO. It will not convert a non-GSO MTU sized packet into a
GSO packet (and you don't even know what the MTU is, so you can't even fix it).
As such your transmit path must *already* be able to handle an MTU 20 bytes
larger then your receive path (for IPv4 to IPv6 translation) - and indeed 28
bytes larger due to IPv4 fragments. Thus removing the skb_decrease_gso_size()
call doesn't actually increase the size of the packets your transmit side must
be able to handle. ie. to handle non-GSO max-MTU packets, the IPv4/IPv6 device/
route MTUs must already be set correctly. Since for example with an IPv4 egress
MTU of 1500, IPv4 to IPv6 translation will already build 1520 byte IPv6 frames,
so you need a 1520 byte device MTU. This means if your IPv6 device's egress
MTU is 1280, your IPv4 route must be 1260 (and actually 1252, because of the
need to handle fragments). This is to handle normal non-GSO packets. Thus the
reduction is simply not needed for GSO packets, because when they're correctly
built, they will already be the right size.

(f) TSO/GSO should be able to exactly undo GRO: the number of packets (TCP
segments) should not be modified, so that TCP's MSS counting works correctly
(this matters for congestion control). If protocol conversion changes the
gso_size, then the number of TCP segments may increase or decrease. Packet loss
after protocol conversion can result in partial loss of MSS segments that the
sender sent. How's the sending TCP stack going to react to receiving ACKs/SACKs
in the middle of the segments it sent?

(g) skb_{decrease,increase}_gso_size() are already no-ops for GSO_BY_FRAGS
case (besides triggering WARN_ON_ONCE). This means you already cannot guarantee
that gso_size (and thus resulting packet MTU) is changed. ie. you must assume
it won't be changed.

(h) changing gso_size is outright buggy for UDP GSO packets, where framing
matters (I believe that's also the case for SCTP, but it's already excluded
by [g]). So the only remaining case is TCP, which also doesn't want it
(see [f]).

(i) see also the reasoning on the previous attempt at fixing this
(commit fa7b83bf3b156c767f3e4a25bbf3817b08f3ff8e) which shows that the current
behaviour causes TCP packet loss:

In the forwarding path GRO -> BPF 6 to 4 -> GSO for TCP traffic, the
coalesced packet payload can be > MSS, but < MSS + 20.

bpf_skb_proto_6_to_4() will upgrade the MSS and it can be > the payload
length. After then tcp_gso_segment checks for the payload length if it
is <= MSS. The condition is causing the packet to be dropped.

tcp_gso_segment():
[...]
mss = skb_shinfo(skb)->gso_size;
if (unlikely(skb->len <= mss)) goto out;
[...]

Thus changing the gso_size is simply a very bad idea. Increasing is unnecessary
and buggy, and decreasing can go negative.

Fixes: 6578171a7ff0 ("bpf: add bpf_skb_change_proto helper")
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dongseok Yi <dseok.yi@samsung.com>
Cc: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/CANP3RGfjLikQ6dg=YpBU0OeHvyv7JOki7CyOUS9modaXAi-9vQ@mail.gmail.com
Link: https://lore.kernel.org/bpf/20210617000953.2787453-2-zenczykowski@gmail.com

Revert "bpf: Check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto"

This reverts commit fa7b83bf3b156c767f3e4a25bbf3817b08f3ff8e.

See the followup commit for the reasoning why I believe the appropriate
approach is to simply make this change without a flag, but it can basically
be summarized as using this helper without the flag is bug-prone or outright
buggy, and thus the default should be this new behaviour.

As this commit has only made it into net-next/master, but not into
any real release, such a backwards incompatible change is still ok.

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dongseok Yi <dseok.yi@samsung.com>
Cc: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/20210617000953.2787453-1-zenczykowski@gmail.com

bpf: Support socket migration by eBPF.

This patch introduces a new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT
to check if the attached eBPF program is capable of migrating sockets. When
the eBPF program is attached, we run it for socket migration if the
expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE or
net.ipv4.tcp_migrate_req is enabled.

Currently, the expected_attach_type is not enforced for the
BPF_PROG_TYPE_SK_REUSEPORT type of program. Thus, this commit follows the
earlier idea in the commit aac3fc320d94 ("bpf: Post-hooks for sys_bind") to
fix up the zero expected_attach_type in bpf_prog_load_fixup_attach_type().

Moreover, this patch adds a new field (migrating_sk) to sk_reuseport_md to
select a new listener based on the child socket. migrating_sk varies
depending on if it is migrating a request in the accept queue or during
3WHS.

- accept_queue : sock (ESTABLISHED/SYN_RECV)
- 3WHS : request_sock (NEW_SYN_RECV)

In the eBPF program, we can select a new listener by
BPF_FUNC_sk_select_reuseport(). Also, we can cancel migration by returning
SK_DROP. This feature is useful when listeners have different settings at
the socket API level or when we want to free resources as soon as possible.

- SK_PASS with selected_sk, select it as a new listener
- SK_PASS with selected_sk NULL, fallbacks to the random selection
- SK_DROP, cancel the migration.

There is a noteworthy point. We select a listening socket in three places,
but we do not have struct skb at closing a listener or retransmitting a
SYN+ACK. On the other hand, some helper functions do not expect skb is NULL
(e.g. skb_header_pointer() in BPF_FUNC_skb_load_bytes(), skb_tail_pointer()
in BPF_FUNC_skb_load_bytes_relative()). So we allocate an empty skb
temporarily before running the eBPF program.

Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6tg6h@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201203042402.6cskdlit5f3mw4ru@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201209030903.hhow5r53l6fmozjn@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/bpf/20210612123224.12525-10-kuniyu@amazon.co.jp

bpf: Support BPF_FUNC_get_socket_cookie() for BPF_PROG_TYPE_SK_REUSEPORT.

We will call sock_reuseport.prog for socket migration in the next commit,
so the eBPF program has to know which listener is closing to select a new
listener.

We can currently get a unique ID of each listener in the userspace by
calling bpf_map_lookup_elem() for BPF_MAP_TYPE_REUSEPORT_SOCKARRAY map.

This patch makes the pointer of sk available in sk_reuseport_md so that we
can get the ID by BPF_FUNC_get_socket_cookie() in the eBPF program.

Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/netdev/20201119001154.kapwihc2plp4f7zc@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/bpf/20210612123224.12525-9-kuniyu@amazon.co.jp

xdp: Extend xdp_redirect_map with broadcast support

This patch adds two flags BPF_F_BROADCAST and BPF_F_EXCLUDE_INGRESS to
extend xdp_redirect_map for broadcast support.

With BPF_F_BROADCAST the packet will be broadcasted to all the interfaces
in the map. with BPF_F_EXCLUDE_INGRESS the ingress interface will be
excluded when do broadcasting.

When getting the devices in dev hash map via dev_map_hash_get_next_key(),
there is a possibility that we fall back to the first key when a device
was removed. This will duplicate packets on some interfaces. So just walk
the whole buckets to avoid this issue. For dev array map, we also walk the
whole map to find valid interfaces.

Function bpf_clear_redirect_map() was removed in
commit ee75aef23afe ("bpf, xdp: Restructure redirect actions").
Add it back as we need to use ri->map again.

With test topology:
+-------------------+ +-------------------+
| Host A (i40e 10G) | ---------- | eno1(i40e 10G) |
+-------------------+ | |
| Host B |
+-------------------+ | |
| Host C (i40e 10G) | ---------- | eno2(i40e 10G) |
+-------------------+ | |
| +------+ |
| veth0 -- | Peer | |
| veth1 -- | | |
| veth2 -- | NS | |
| +------+ |
+-------------------+

On Host A:
# pktgen/pktgen_sample03_burst_single_flow.sh -i eno1 -d $dst_ip -m $dst_mac -s 64

On Host B(Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz, 128G Memory):
Use xdp_redirect_map and xdp_redirect_map_multi in samples/bpf for testing.
All the veth peers in the NS have a XDP_DROP program loaded. The
forward_map max_entries in xdp_redirect_map_multi is modify to 4.

Testing the performance impact on the regular xdp_redirect path with and
without patch (to check impact of additional check for broadcast mode):

5.12 rc4 | redirect_map i40e->i40e | 2.0M | 9.7M
5.12 rc4 | redirect_map i40e->veth | 1.7M | 11.8M
5.12 rc4 + patch | redirect_map i40e->i40e | 2.0M | 9.6M
5.12 rc4 + patch | redirect_map i40e->veth | 1.7M | 11.7M

Testing the performance when cloning packets with the redirect_map_multi
test, using a redirect map size of 4, filled with 1-3 devices:

5.12 rc4 + patch | redirect_map multi i40e->veth (x1) | 1.7M | 11.4M
5.12 rc4 + patch | redirect_map multi i40e->veth (x2) | 1.1M | 4.3M
5.12 rc4 + patch | redirect_map multi i40e->veth (x3) | 0.8M | 2.6M

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210519090747.1655268-3-liuhangbin@gmail.com

bpf: Check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto

In the forwarding path GRO -> BPF 6 to 4 -> GSO for TCP traffic, the
coalesced packet payload can be > MSS, but < MSS + 20.

bpf_skb_proto_6_to_4() will upgrade the MSS and it can be > the payload
length. After then tcp_gso_segment checks for the payload length if it
is <= MSS. The condition is causing the packet to be dropped.

tcp_gso_segment():
[...]
mss = skb_shinfo(skb)->gso_size;
if (unlikely(skb->len <= mss))
goto out;
[...]

Allow to upgrade/downgrade MSS only when BPF_F_ADJ_ROOM_FIXED_GSO is
not set.

Signed-off-by: Dongseok Yi <dseok.yi@samsung.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/1620804453-57566-1-git-send-email-dseok.yi@samsung.com

locking/atomic: net: use linux/atomic.h for xchg & cmpxchg

As xchg*() and cmpxchg*() may be instrumented by atomic-instrumented.h,
it's necessary to include <linux/atomic.h> to use these, rather than
<asm/cmpxchg.h>, which is effectively an arch-internal header.

In a couple of places we include <asm/cmpxchg.h>, but get away with this
as <linux/atomic.h> gets pulled in inidrectly by another include. Before
we convert more architectures to use atomic-instrumented.h, let's fix
these up to use <linux/atomic.h> so that we don't make things more
fragile.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210525140232.53872-3-mark.rutland@arm.com

bpf: Set mac_len in bpf_skb_change_head

The skb_change_head() helper did not set "skb->mac_len", which is
problematic when it's used in combination with skb_redirect_peer().
Without it, redirecting a packet from a L3 device such as wireguard to
the veth peer device will cause skb->data to point to the middle of the
IP header on entry to tcp_v4_rcv() since the L2 header is not pulled
correctly due to mac_len=0.

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Jussi Maki <joamaki@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210519154743.2554771-2-joamaki@gmail.com

bpf: selftests: Add kfunc_call test

This patch adds a few kernel function bpf_kfunc_call_test*() for the
selftest's test_run purpose. They will be allowed for tc_cls prog.

The selftest calling the kernel function bpf_kfunc_call_test*()
is also added in this patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015252.1551395-1-kafai@fb.com

bpf: Add getter and setter for SO_REUSEPORT through bpf_{g,s}etsockopt

Augment the current set of options that are accessible via
bpf_{g,s}etsockopt to also support SO_REUSEPORT.

Signed-off-by: Manu Bretelle <chantra@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210310182305.1910312-1-chantra@fb.com

bpf, xdp: Restructure redirect actions

The XDP_REDIRECT implementations for maps and non-maps are fairly
similar, but obviously need to take different code paths depending on
if the target is using a map or not. Today, the redirect targets for
XDP either uses a map, or is based on ifindex.

Here, the map type and id are added to bpf_redirect_info, instead of
the actual map. Map type, map item/ifindex, and the map_id (if any) is
passed to xdp_do_redirect().

For ifindex-based redirect, used by the bpf_redirect() XDP BFP helper,
a special map type/id are used. Map type of UNSPEC together with map id
equal to INT_MAX has the special meaning of an ifindex based
redirect. Note that valid map ids are 1 inclusive, INT_MAX exclusive
([1,INT_MAX[).

In addition to making the code easier to follow, using explicit type
and id in bpf_redirect_info has a slight positive performance impact
by avoiding a pointer indirection for the map type lookup, and instead
use the cacheline for bpf_redirect_info.

Since the actual map is not passed via bpf_redirect_info anymore, the
map lookup is only done in the BPF helper. This means that the
bpf_clear_redirect_map() function can be removed. The actual map item
is RCU protected.

The bpf_redirect_info flags member is not used by XDP, and not
read/written any more. The map member is only written to when
required/used, and not unconditionally.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com

bpf, xdp: Make bpf_redirect_map() a map operation

Currently the bpf_redirect_map() implementation dispatches to the
correct map-lookup function via a switch-statement. To avoid the
dispatching, this change adds bpf_redirect_map() as a map
operation. Each map provides its bpf_redirect_map() version, and
correct function is automatically selected by the BPF verifier.

A nice side-effect of the code movement is that the map lookup
functions are now local to the map implementation files, which removes
one additional function call.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com

bpf: Add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_ENCAP_L2_ETH

bpf_skb_adjust_room sets the inner_protocol as skb->protocol for packets
encapsulation. But that is not appropriate when pushing Ethernet header.

Add an option to further specify encap L2 type and set the inner_protocol
as ETH_P_TEB.

Suggested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Xuesen Huang <huangxuesen@kuaishou.com>
Signed-off-by: Zhiyong Cheng <chengzhiyong@kuaishou.com>
Signed-off-by: Li Wang <wangli09@kuaishou.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/20210304064046.6232-1-hxseverything@gmail.com

bpf: Add PROG_TEST_RUN support for sk_lookup programs

Allow to pass sk_lookup programs to PROG_TEST_RUN. User space
provides the full bpf_sk_lookup struct as context. Since the
context includes a socket pointer that can't be exposed
to user space we define that PROG_TEST_RUN returns the cookie
of the selected socket or zero in place of the socket pointer.

We don't support testing programs that select a reuseport socket,
since this would mean running another (unrelated) BPF program
from the sk_lookup test handler.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210303101816.36774-3-lmb@cloudflare.com

bpf: Compute data_end dynamically with JIT code

Currently, we compute ->data_end with a compile-time constant
offset of skb. But as Jakub pointed out, we can actually compute
it in eBPF JIT code at run-time, so that we can competely get
rid of ->data_end. This is similar to skb_shinfo(skb) computation
in bpf_convert_shinfo_access().

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210223184934.6054-4-xiyou.wangcong@gmail.com

bpf: BPF-helper for MTU checking add length input

The FIB lookup example[1] show how the IP-header field tot_len
(iph->tot_len) is used as input to perform the MTU check.

This patch extend the BPF-helper bpf_check_mtu() with the same ability
to provide the length as user parameter input, via mtu_len parameter.

This still needs to be done before the bpf_check_mtu() helper API
becomes frozen.

[1] samples/bpf/xdp_fwd_kern.c

Fixes: 34b2021cc616 ("bpf: Add BPF-helper for MTU checking")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161521555850.3515614.6533850861569774444.stgit@firesoul

bpf: Drop MTU check when doing TC-BPF redirect to ingress

The use-case for dropping the MTU check when TC-BPF does redirect to
ingress, is described by Eyal Birger in email[0]. The summary is the
ability to increase packet size (e.g. with IPv6 headers for NAT64) and
ingress redirect packet and let normal netstack fragment packet as needed.

[0] https://lore.kernel.org/netdev/CAHsH6Gug-hsLGHQ6N0wtixdOa85LDZ3HNRHVd0opR=19Qo4W4Q@mail.gmail.com/

V15:
- missing static for function declaration

V9:
- Make net_device "up" (IFF_UP) check explicit in skb_do_redirect

V4:
- Keep net_device "up" (IFF_UP) check.
- Adjustment to handle bpf_redirect_peer() helper

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287790971.790810.11785274340154740591.stgit@firesoul

bpf: Add BPF-helper for MTU checking

This BPF-helper bpf_check_mtu() works for both XDP and TC-BPF programs.

The SKB object is complex and the skb->len value (accessible from
BPF-prog) also include the length of any extra GRO/GSO segments, but
without taking into account that these GRO/GSO segments get added
transport (L4) and network (L3) headers before being transmitted. Thus,
this BPF-helper is created such that the BPF-programmer don't need to
handle these details in the BPF-prog.

The API is designed to help the BPF-programmer, that want to do packet
context size changes, which involves other helpers. These other helpers
usually does a delta size adjustment. This helper also support a delta
size (len_diff), which allow BPF-programmer to reuse arguments needed by
these other helpers, and perform the MTU check prior to doing any actual
size adjustment of the packet context.

It is on purpose, that we allow the len adjustment to become a negative
result, that will pass the MTU check. This might seem weird, but it's not
this helpers responsibility to "catch" wrong len_diff adjustments. Other
helpers will take care of these checks, if BPF-programmer chooses to do
actual size adjustment.

V14:
- Improve man-page desc of len_diff.

V13:
- Enforce flag BPF_MTU_CHK_SEGS cannot use len_diff.

V12:
- Simplify segment check that calls skb_gso_validate_network_len.
- Helpers should return long

V9:
- Use dev->hard_header_len (instead of ETH_HLEN)
- Annotate with unlikely req from Daniel
- Fix logic error using skb_gso_validate_network_len from Daniel

V6:
- Took John's advice and dropped BPF_MTU_CHK_RELAX
- Returned MTU is kept at L3-level (like fib_lookup)

V4: Lot of changes
- ifindex 0 now use current netdev for MTU lookup
- rename helper from bpf_mtu_check to bpf_check_mtu
- fix bug for GSO pkt length (as skb->len is total len)
- remove __bpf_len_adj_positive, simply allow negative len adj

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287790461.790810.3429728639563297353.stgit@firesoul

bpf: bpf_fib_lookup return MTU value as output when looked up

The BPF-helpers for FIB lookup (bpf_xdp_fib_lookup and bpf_skb_fib_lookup)
can perform MTU check and return BPF_FIB_LKUP_RET_FRAG_NEEDED. The BPF-prog
don't know the MTU value that caused this rejection.

If the BPF-prog wants to implement PMTU (Path MTU Discovery) (rfc1191) it
need to know this MTU value for the ICMP packet.

Patch change lookup and result struct bpf_fib_lookup, to contain this MTU
value as output via a union with 'tot_len' as this is the value used for
the MTU lookup.

V5:
- Fixed uninit value spotted by Dan Carpenter.
- Name struct output member mtu_result

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287789952.790810.13134700381067698781.stgit@firesoul

bpf: Fix bpf_fib_lookup helper MTU check for SKB ctx

BPF end-user on Cilium slack-channel (Carlo Carraro) wants to use
bpf_fib_lookup for doing MTU-check, but *prior* to extending packet size,
by adjusting fib_params 'tot_len' with the packet length plus the expected
encap size. (Just like the bpf_check_mtu helper supports). He discovered
that for SKB ctx the param->tot_len was not used, instead skb->len was used
(via MTU check in is_skb_forwardable() that checks against netdev MTU).

Fix this by using fib_params 'tot_len' for MTU check. If not provided (e.g.
zero) then keep existing TC behaviour intact. Notice that 'tot_len' for MTU
check is done like XDP code-path, which checks against FIB-dst MTU.

V16:
- Revert V13 optimization, 2nd lookup is against egress/resulting netdev

V13:
- Only do ifindex lookup one time, calling dev_get_by_index_rcu().

V10:
- Use same method as XDP for 'tot_len' MTU check

Fixes: 4c79579b44b1 ("bpf: Change bpf_fib_lookup to return lookup status")
Reported-by: Carlo Carraro <colrack@gmail.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/161287789444.790810.15247494756551413508.stgit@firesoul

bpf: Remove MTU check in __bpf_skb_max_len

Multiple BPF-helpers that can manipulate/increase the size of the SKB uses
__bpf_skb_max_len() as the max-length. This function limit size against
the current net_device MTU (skb->dev->mtu).

When a BPF-prog grow the packet size, then it should not be limited to the
MTU. The MTU is a transmit limitation, and software receiving this packet
should be allowed to increase the size. Further more, current MTU check in
__bpf_skb_max_len uses the MTU from ingress/current net_device, which in
case of redirects uses the wrong net_device.

This patch keeps a sanity max limit of SKB_MAX_ALLOC (16KiB). The real limit
is elsewhere in the system. Jesper's testing[1] showed it was not possible
to exceed 8KiB when expanding the SKB size via BPF-helper. The limiting
factor is the define KMALLOC_MAX_CACHE_SIZE which is 8192 for
SLUB-allocator (CONFIG_SLUB) in-case PAGE_SIZE is 4096. This define is
in-effect due to this being called from softirq context see code
__gfp_pfmemalloc_flags() and __do_kmalloc_node(). Jakub's testing showed
that frames above 16KiB can cause NICs to reset (but not crash). Keep this
sanity limit at this level as memory layer can differ based on kernel
config.

[1] https://github.com/xdp-project/bpf-examples/tree/master/MTU-tests

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287788936.790810.2937823995775097177.stgit@firesoul

net/sock: Add kernel config SOCK_RX_QUEUE_MAPPING

Use a new config SOCK_RX_QUEUE_MAPPING to compile-in the socket
RX queue field and logic, instead of the XPS config.
This breaks dependency in XPS, and allows selecting it from non-XPS
use cases, as we do in the next patch.

In addition, use the new flag to wrap the logic in sk_rx_queue_get()
and protect access to the sk_rx_queue_mapping field, while keeping
the function exposed unconditionally, just like sk_rx_queue_set()
and sk_rx_queue_clear().

Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Expose bpf_get_socket_cookie to tracing programs

This needs a new helper that:
- can work in a sleepable context (using sock_gen_cookie)
- takes a struct sock pointer and checks that it's not NULL

Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210111406.785541-2-revest@chromium.org

net: initialize net->net_cookie at netns setup

It is simpler to make net->net_cookie a plain u64
written once in setup_net() instead of looping
and using atomic64 helpers.

Lorenz Bauer wants to add SO_NETNS_COOKIE socket option
and this patch would makes his patch series simpler.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: Enable bpf_{g,s}etsockopt in BPF_CGROUP_UDP{4,6}_RECVMSG

Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on a locked socket.

Note that we could remove the switch for prog->expected_attach_type altogether
since all current sock_addr attach types are covered. However, it makes sense
to keep it as a safe-guard in case new sock_addr attach types are added that
might not operate on a locked socket. Therefore, avoid to let this slip through.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-5-sdf@google.com

bpf: Enable bpf_{g,s}etsockopt in BPF_CGROUP_INET{4,6}_GET{PEER,SOCK}NAME

Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on
a locked socket.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-3-sdf@google.com

bpf: Enable bpf_{g,s}etsockopt in BPF_CGROUP_UDP{4,6}_SENDMSG

Can be used to query/modify socket state for unconnected UDP sendmsg.
Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on
a locked socket.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-2-sdf@google.com

bpf: Allow to retrieve sol_socket opts from sock_addr progs

The _bpf_setsockopt() is able to set some of the SOL_SOCKET level options,
however, _bpf_getsockopt() has little support to actually retrieve them.
This small patch adds few misc options such as SO_MARK, SO_PRIORITY and
SO_BINDTOIFINDEX. For the latter getter and setter are added. The mark and
priority in particular allow to retrieve the options from BPF cgroup hooks
to then implement custom behavior / settings on the syscall hooks compared
to other sockets that stick to the defaults, for example.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/cba44439b801e5ddc1170e5be787f4dc93a2d7f9.1610406333.git.daniel@iogearbox.net

bpf: Only provide bpf_sock_from_file with CONFIG_NET

This moves the bpf_sock_from_file definition into net/core/filter.c
which only gets compiled with CONFIG_NET and also moves the helper proto
usage next to other tracing helpers that are conditional on CONFIG_NET.

This avoids
ld: kernel/trace/bpf_trace.o: in function `bpf_sock_from_file':
bpf_trace.c:(.text+0xe23): undefined reference to `sock_from_file'
When compiling a kernel with BPF and without NET.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20201208173623.1136863-1-revest@chromium.org

bpf: Adds support for setting window clamp

Adds a new bpf_setsockopt for TCP sockets, TCP_BPF_WINDOW_CLAMP,
which sets the maximum receiver window size. It will be useful for
limiting receiver window based on RTT.

Signed-off-by: Prankur gupta <prankgup@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201202213152.435886-2-prankgup@fb.com

bpf: Allow bpf_{s,g}etsockopt from cgroup bind{4,6} hooks

I have to now lock/unlock socket for the bind hook execution.
That shouldn't cause any overhead because the socket is unbound
and shouldn't receive any traffic.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrey Ignatov <rdna@fb.com>
Link: https://lore.kernel.org/bpf/20201202172516.3483656-3-sdf@google.com

net: Properly typecast int values to set sk_max_pacing_rate

In setsockopt(SO_MAX_PACING_RATE) on 64bit systems, sk_max_pacing_rate,
after extended from 'u32' to 'unsigned long', takes unintentionally
hiked value whenever assigned from an 'int' value with MSB=1, due to
binary sign extension in promoting s32 to u64, e.g. 0x80000000 becomes
0xFFFFFFFF80000000.

Thus inflated sk_max_pacing_rate causes subsequent getsockopt to return
~0U unexpectedly. It may also result in increased pacing rate.

Fix by explicitly casting the 'int' value to 'unsigned int' before
assigning it to sk_max_pacing_rate, for zero extension to happen.

Fixes: 76a9ebe811fb ("net: extend sk_pacing_rate to unsigned long")
Signed-off-by: Ji Li <jli@akamai.com>
Signed-off-by: Ke Li <keli@akamai.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201022064146.79873-1-keli@akamai.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf: Fix bpf_redirect_neigh helper api to support supplying nexthop

Based on the discussion in [0], update the bpf_redirect_neigh() helper to
accept an optional parameter specifying the nexthop information. This makes
it possible to combine bpf_fib_lookup() and bpf_redirect_neigh() without
incurring a duplicate FIB lookup - since the FIB lookup helper will return
the nexthop information even if no neighbour is present, this can simply
be passed on to bpf_redirect_neigh() if bpf_fib_lookup() returns
BPF_FIB_LKUP_RET_NO_NEIGH. Thus fix & extend it before helper API is frozen.

[0] https://lore.kernel.org/bpf/393e17fc-d187-3a8d-2f0d-a627c7c63fca@iogearbox.net/

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/bpf/160322915615.32199.1187570224032024535.stgit@toke.dk

bpf: Always return target ifindex in bpf_fib_lookup

The bpf_fib_lookup() helper performs a neighbour lookup for the destination
IP and returns BPF_FIB_LKUP_NO_NEIGH if this fails, with the expectation
that the BPF program will pass the packet up the stack in this case.
However, with the addition of bpf_redirect_neigh() that can be used instead
to perform the neighbour lookup, at the cost of a bit of duplicated work.

For that we still need the target ifindex, and since bpf_fib_lookup()
already has that at the time it performs the neighbour lookup, there is
really no reason why it can't just return it in any case. So let's just
always return the ifindex if the FIB lookup itself succeeds.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Link: https://lore.kernel.org/bpf/20201009184234.134214-1-toke@redhat.com

bpf: Add redirect_peer helper

Add an efficient ingress to ingress netns switch that can be used out of tc BPF
programs in order to redirect traffic from host ns ingress into a container
veth device ingress without having to go via CPU backlog queue [0]. For local
containers this can also be utilized and path via CPU backlog queue only needs
to be taken once, not twice. On a high level this borrows from ipvlan which does
similar switch in __netif_receive_skb_core() and then iterates via another_round.
This helps to reduce latency for mentioned use cases.

Pod to remote pod with redirect(), TCP_RR [1]:

# percpu_netperf 10.217.1.33
RT_LATENCY: 122.450 (per CPU: 122.666 122.401 122.333 122.401 )
MEAN_LATENCY: 121.210 (per CPU: 121.100 121.260 121.320 121.160 )
STDDEV_LATENCY: 120.040 (per CPU: 119.420 119.910 125.460 115.370 )
MIN_LATENCY: 46.500 (per CPU: 47.000 47.000 47.000 45.000 )
P50_LATENCY: 118.500 (per CPU: 118.000 119.000 118.000 119.000 )
P90_LATENCY: 127.500 (per CPU: 127.000 128.000 127.000 128.000 )
P99_LATENCY: 130.750 (per CPU: 131.000 131.000 129.000 132.000 )

TRANSACTION_RATE: 32666.400 (per CPU: 8152.200 8169.842 8174.439 8169.897 )

Pod to remote pod with redirect_peer(), TCP_RR:

# percpu_netperf 10.217.1.33
RT_LATENCY: 44.449 (per CPU: 43.767 43.127 45.279 45.622 )
MEAN_LATENCY: 45.065 (per CPU: 44.030 45.530 45.190 45.510 )
STDDEV_LATENCY: 84.823 (per CPU: 66.770 97.290 84.380 90.850 )
MIN_LATENCY: 33.500 (per CPU: 33.000 33.000 34.000 34.000 )
P50_LATENCY: 43.250 (per CPU: 43.000 43.000 43.000 44.000 )
P90_LATENCY: 46.750 (per CPU: 46.000 47.000 47.000 47.000 )
P99_LATENCY: 52.750 (per CPU: 51.000 54.000 53.000 53.000 )

TRANSACTION_RATE: 90039.500 (per CPU: 22848.186 23187.089 22085.077 21919.130 )

[0] https://linuxplumbersconf.org/event/7/contributions/674/attachments/568/1002/plumbers_2020_cilium_load_balancer.pdf
[1] https://github.com/borkmann/netperf_scripts/blob/master/percpu_netperf

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201010234006.7075-3-daniel@iogearbox.net

bpf: Add tcp_notsent_lowat bpf setsockopt

Adding support for TCP_NOTSENT_LOWAT sockoption (https://lwn.net/Articles/560082/)
in tcp bpf programs.

Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20201009070325.226855-1-tehnerd@tehnerd.com

bpf, sockmap: Add skb_adjust_room to pop bytes off ingress payload

This implements a new helper skb_adjust_room() so users can push/pop
extra bytes from a BPF_SK_SKB_STREAM_VERDICT program.

Some protocols may include headers and other information that we may
not want to include when doing a redirect from a BPF_SK_SKB_STREAM_VERDICT
program. One use case is to redirect TLS packets into a receive socket
that doesn't expect TLS data. In TLS case the first 13B or so contain the
protocol header. With KTLS the payload is decrypted so we should be able
to redirect this to a receiving socket, but the receiving socket may not
be expecting to receive a TLS header and discard the data. Using the
above helper we can pop the header off and put an appropriate header on
the payload. This allows for creating a proxy between protocols without
extra hops through the stack or userspace.

So in order to fix this case add skb_adjust_room() so users can strip the
header. After this the user can strip the header and an unmodified receiver
thread will work correctly when data is redirected into the ingress path
of a sock.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/160160099197.7052.8443193973242831692.stgit@john-Precision-5820-Tower

bpf: Fix "unresolved symbol" build error with resolve_btfids

Michal reported a build failure likes below:

BTFIDS vmlinux
FAILED unresolved symbol tcp_timewait_sock
make[1]: *** [/.../linux-5.9-rc7/Makefile:1176: vmlinux] Error 255

This error can be triggered when config has CONFIG_NET enabled
but CONFIG_INET disabled. In this case, there is no user of
istructs inet_timewait_sock and tcp_timewait_sock and hence
vmlinux BTF types are not generated for these two structures.

To fix the problem, let us force BTF generation for these two
structures with BTF_TYPE_EMIT.

Fixes: fce557bcef11 ("bpf: Make btf_sock_ids global")
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201001051339.2549085-1-yhs@fb.com

bpf: Add redirect_neigh helper as redirect drop-in

Add a redirect_neigh() helper as redirect() drop-in replacement
for the xmit side. Main idea for the helper is to be very similar
in semantics to the latter just that the skb gets injected into
the neighboring subsystem in order to let the stack do the work
it knows best anyway to populate the L2 addresses of the packet
and then hand over to dev_queue_xmit() as redirect() does.

This solves two bigger items: i) skbs don't need to go up to the
stack on the host facing veth ingress side for traffic egressing
the container to achieve the same for populating L2 which also
has the huge advantage that ii) the skb->sk won't get orphaned in
ip_rcv_core() when entering the IP routing layer on the host stack.

Given that skb->sk neither gets orphaned when crossing the netns
as per 9c4c325252c5 ("skbuff: preserve sock reference when scrubbing
the skb.") the helper can then push the skbs directly to the phys
device where FQ scheduler can do its work and TCP stack gets proper
backpressure given we hold on to skb->sk as long as skb is still
residing in queues.

With the helper used in BPF data path to then push the skb to the
phys device, I observed a stable/consistent TCP_STREAM improvement
on veth devices for traffic going container -> host -> host ->
container from ~10Gbps to ~15Gbps for a single stream in my test
environment.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Cc: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/bpf/f207de81629e1724899b73b8112e0013be782d35.1601477936.git.daniel@iogearbox.net

bpf, net: Rework cookie generator as per-cpu one

With its use in BPF, the cookie generator can be called very frequently
in particular when used out of cgroup v2 hooks (e.g. connect / sendmsg)
and attached to the root cgroup, for example, when used in v1/v2 mixed
environments. In particular, when there's a high churn on sockets in the
system there can be many parallel requests to the bpf_get_socket_cookie()
and bpf_get_netns_cookie() helpers which then cause contention on the
atomic counter.

As similarly done in f991bd2e1421 ("fs: introduce a per-cpu last_ino
allocator"), add a small helper library that both can use for the 64 bit
counters. Given this can be called from different contexts, we also need
to deal with potential nested calls even though in practice they are
considered extremely rare. One idea as suggested by Eric Dumazet was
to use a reverse counter for this situation since we don't expect 64 bit
overflows anyways; that way, we can avoid bigger gaps in the 64 bit
counter space compared to just batch-wise increase. Even on machines
with small number of cores (e.g. 4) the cookie generation shrinks from
min/max/med/avg (ns) of 22/50/40/38.9 down to 10/35/14/17.3 when run
in parallel from multiple CPUs.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Link: https://lore.kernel.org/bpf/8a80b8d27d3c49f9a14e1d5213c19d8be87d1dc8.1601477936.git.daniel@iogearbox.net

bpf: Add classid helper only based on skb->sk

Similarly to 5a52ae4e32a6 ("bpf: Allow to retrieve cgroup v1 classid
from v2 hooks"), add a helper to retrieve cgroup v1 classid solely
based on the skb->sk, so it can be used as key as part of BPF map
lookups out of tc from host ns, in particular given the skb->sk is
retained these days when crossing net ns thanks to 9c4c325252c5
("skbuff: preserve sock reference when scrubbing the skb."). This
is similar to bpf_skb_cgroup_id() which implements the same for v2.
Kubernetes ecosystem is still operating on v1 however, hence net_cls
needs to be used there until this can be dropped in with the v2
helper of bpf_skb_cgroup_id().

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/ed633cf27a1c620e901c5aa99ebdefb028dce600.1601477936.git.daniel@iogearbox.net

bpf: Change bpf_sk_assign to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON

This patch changes the bpf_sk_assign() to take
ARG_PTR_TO_BTF_ID_SOCK_COMMON such that they will work with the pointer
returned by the bpf_skc_to_*() helpers also.

The bpf_sk_lookup_assign() is taking ARG_PTR_TO_SOCKET_"OR_NULL". Meaning
it specifically takes a literal NULL. ARG_PTR_TO_BTF_ID_SOCK_COMMON
does not allow a literal NULL, so another ARG type is required
for this purpose and another follow-up patch can be used if
there is such need.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200925000415.3857374-1-kafai@fb.com

bpf: Change bpf_tcp_*_syncookie to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON

This patch changes the bpf_tcp_*_syncookie() to take
ARG_PTR_TO_BTF_ID_SOCK_COMMON such that they will work with the pointer
returned by the bpf_skc_to_*() helpers also.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/20200925000409.3856725-1-kafai@fb.com

bpf: Change bpf_sk_release and bpf_sk_*cgroup_id to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON

The previous patch allows the networking bpf prog to use the
bpf_skc_to_*() helpers to get a PTR_TO_BTF_ID socket pointer,
e.g. "struct tcp_sock *". It allows the bpf prog to read all the
fields of the tcp_sock.

This patch changes the bpf_sk_release() and bpf_sk_*cgroup_id()
to take ARG_PTR_TO_BTF_ID_SOCK_COMMON such that they will
work with the pointer returned by the bpf_skc_to_*() helpers
also. For example, the following will work:

sk = bpf_skc_lookup_tcp(skb, tuple, tuplen, BPF_F_CURRENT_NETNS, 0);
if (!sk)
return;
tp = bpf_skc_to_tcp_sock(sk);
if (!tp) {
bpf_sk_release(sk);
return;
}
lsndtime = tp->lsndtime;
/* Pass tp to bpf_sk_release() will also work */
bpf_sk_release(tp);

Since PTR_TO_BTF_ID could be NULL, the helper taking
ARG_PTR_TO_BTF_ID_SOCK_COMMON has to check for NULL at runtime.

A btf_id of "struct sock" may not always mean a fullsock. Regardless
the helper's running context may get a non-fullsock or not,
considering fullsock check/handling is pretty cheap, it is better to
keep the same verifier expectation on helper that takes ARG_PTR_TO_BTF_ID*
will be able to handle the minisock situation. In the bpf_sk_*cgroup_id()
case, it will try to get a fullsock by using sk_to_full_sk() as its
skb variant bpf_sk"b"_*cgroup_id() has already been doing.

bpf_sk_release can already handle minisock, so nothing special has to
be done.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200925000356.3856047-1-kafai@fb.com

bpf: Enable bpf_skc_to_* sock casting helper to networking prog type

There is a constant need to add more fields into the bpf_tcp_sock
for the bpf programs running at tc, sock_ops...etc.

A current workaround could be to use bpf_probe_read_kernel(). However,
other than making another helper call for reading each field and missing
CO-RE, it is also not as intuitive to use as directly reading
"tp->lsndtime" for example. While already having perfmon cap to do
bpf_probe_read_kernel(), it will be much easier if the bpf prog can
directly read from the tcp_sock.

This patch tries to do that by using the existing casting-helpers
bpf_skc_to_*() whose func_proto returns a btf_id. For example, the
func_proto of bpf_skc_to_tcp_sock returns the btf_id of the
kernel "struct tcp_sock".

These helpers are also added to is_ptr_cast_function().
It ensures the returning reg (BPF_REF_0) will also carries the ref_obj_id.
That will keep the ref-tracking works properly.

The bpf_skc_to_* helpers are made available to most of the bpf prog
types in filter.c. The bpf_skc_to_* helpers will be limited by
perfmon cap.

This patch adds a ARG_PTR_TO_BTF_ID_SOCK_COMMON. The helper accepting
this arg can accept a btf-id-ptr (PTR_TO_BTF_ID + &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON])
or a legacy-ctx-convert-skc-ptr (PTR_TO_SOCK_COMMON). The bpf_skc_to_*()
helpers are changed to take ARG_PTR_TO_BTF_ID_SOCK_COMMON such that
they will accept pointer obtained from skb->sk.

Instead of specifying both arg_type and arg_btf_id in the same func_proto
which is how the current ARG_PTR_TO_BTF_ID does, the arg_btf_id of
the new ARG_PTR_TO_BTF_ID_SOCK_COMMON is specified in the
compatible_reg_types[] in verifier.c. The reason is the arg_btf_id is
always the same. Discussion in this thread:
https://lore.kernel.org/bpf/20200922070422.1917351-1-kafai@fb.com/

The ARG_PTR_TO_BTF_ID_ part gives a clear expectation that the helper is
expecting a PTR_TO_BTF_ID which could be NULL. This is the same
behavior as the existing helper taking ARG_PTR_TO_BTF_ID.

The _SOCK_COMMON part means the helper is also expecting the legacy
SOCK_COMMON pointer.

By excluding the _OR_NULL part, the bpf prog cannot call helper
with a literal NULL which doesn't make sense in most cases.
e.g. bpf_skc_to_tcp_sock(NULL) will be rejected. All PTR_TO_*_OR_NULL
reg has to do a NULL check first before passing into the helper or else
the bpf prog will be rejected. This behavior is nothing new and
consistent with the current expectation during bpf-prog-load.

[ ARG_PTR_TO_BTF_ID_SOCK_COMMON will be used to replace
ARG_PTR_TO_SOCK* of other existing helpers later such that
those existing helpers can take the PTR_TO_BTF_ID returned by
the bpf_skc_to_*() helpers.

The only special case is bpf_sk_lookup_assign() which can accept a
literal NULL ptr. It has to be handled specially in another follow
up patch if there is a need (e.g. by renaming ARG_PTR_TO_SOCKET_OR_NULL
to ARG_PTR_TO_BTF_ID_SOCK_COMMON_OR_NULL). ]

[ When converting the older helpers that take ARG_PTR_TO_SOCK* in
the later patch, if the kernel does not support BTF,
ARG_PTR_TO_BTF_ID_SOCK_COMMON will behave like ARG_PTR_TO_SOCK_COMMON
because no reg->type could have PTR_TO_BTF_ID in this case.

It is not a concern for the newer-btf-only helper like the bpf_skc_to_*()
here though because these helpers must require BTF vmlinux to begin
with. ]

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200925000350.3855720-1-kafai@fb.com

bpf: Allow specifying a BTF ID per argument in function protos

Function prototypes using ARG_PTR_TO_BTF_ID currently use two ways to signal
which BTF IDs are acceptable. First, bpf_func_proto.btf_id is an array of
IDs, one for each argument. This array is only accessed up to the highest
numbered argument that uses ARG_PTR_TO_BTF_ID and may therefore be less than
five arguments long. It usually points at a BTF_ID_LIST. Second, check_btf_id
is a function pointer that is called by the verifier if present. It gets the
actual BTF ID of the register, and the argument number we're currently checking.
It turns out that the only user check_arg_btf_id ignores the argument, and is
simply used to check whether the BTF ID has a struct sock_common at it's start.

Replace both of these mechanisms with an explicit BTF ID for each argument
in a function proto. Thanks to btf_struct_ids_match this is very flexible:
check_arg_btf_id can be replaced by requiring struct sock_common.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-5-lmb@cloudflare.com

bpf: Bpf_skc_to_* casting helpers require a NULL check on sk

The bpf_skc_to_* type casting helpers are available to
BPF_PROG_TYPE_TRACING. The traced PTR_TO_BTF_ID may be NULL.
For example, the skb->sk may be NULL. Thus, these casting helpers
need to check "!sk" also and this patch fixes them.

Fixes: 0d4fad3e57df ("bpf: Add bpf_skc_to_udp6_sock() helper")
Fixes: 478cfbdf5f13 ("bpf: Add bpf_skc_to_{tcp, tcp_timewait, tcp_request}_sock() helpers")
Fixes: af7ec1383361 ("bpf: Add bpf_skc_to_tcp6_sock() helper")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200915182959.241101-1-kafai@fb.com

ipv4: Initialize flowi4_multipath_hash in data path

flowi4_multipath_hash was added by the commit referenced below for
tunnels. Unfortunately, the patch did not initialize the new field
for several fast path lookups that do not initialize the entire flow
struct to 0. Fix those locations. Currently, flowi4_multipath_hash
is random garbage and affects the hash value computed by
fib_multipath_hash for multipath selection.

Fixes: 24ba14406c5c ("route: Add multipath_hash in flowi_common to make user-define hash")
Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: simplify _bpf_setsockopt(): Remove flags argument

Now that the previous patches have removed the code that uses the
flags argument to _bpf_setsockopt(), we can remove that argument.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>

tcp: simplify tcp_set_congestion_control(): Always reinitialize

Now that the previous patches ensure that all call sites for
tcp_set_congestion_control() want to initialize congestion control, we
can simplify tcp_set_congestion_control() by removing the reinit
argument and the code to support it.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>

tcp: Simplify EBPF TCP_CONGESTION to always init CC

Now that the previous patch ensures we don't initialize the congestion
control twice, when EBPF sets the congestion control algorithm at
connection establishment we can simplify the code by simply
initializing the congestion control module at that time.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>

bpf: Fix clobbering of r2 in bpf_gen_ld_abs

Bryce reported that he saw the following with:

0: r6 = r1
1: r1 = 12
2: r0 = *(u16 *)skb[r1]

The xlated sequence was incorrectly clobbering r2 with pointer
value of r6 ...

0: (bf) r6 = r1
1: (b7) r1 = 12
2: (bf) r1 = r6
3: (bf) r2 = r1
4: (85) call bpf_skb_load_helper_16_no_cache#7692160

... and hence call to the load helper never succeeded given the
offset was too high. Fix it by reordering the load of r6 to r1.

Other than that the insn has similar calling convention than BPF
helpers, that is, r0 - r5 are scratch regs, so nothing else
affected after the insn.

Fixes: e0cea7ce988c ("bpf: implement ld_abs/ld_ind in native bpf")
Reported-by: Bryce Kahle <bryce.kahle@datadoghq.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/cace836e4d07bb63b1a53e49c5dfb238a040c298.1599512096.git.daniel@iogearbox.net

tcp: bpf: Optionally store mac header in TCP_SAVE_SYN

This patch is adapted from Eric's patch in an earlier discussion [1].

The TCP_SAVE_SYN currently only stores the network header and
tcp header. This patch allows it to optionally store
the mac header also if the setsockopt's optval is 2.

It requires one more bit for the "save_syn" bit field in tcp_sock.
This patch achieves this by moving the syn_smc bit next to the is_mptcp.
The syn_smc is currently used with the TCP experimental option. Since
syn_smc is only used when CONFIG_SMC is enabled, this patch also puts
the "IS_ENABLED(CONFIG_SMC)" around it like the is_mptcp did
with "IS_ENABLED(CONFIG_MPTCP)".

The mac_hdrlen is also stored in the "struct saved_syn"
to allow a quick offset from the bpf prog if it chooses to start
getting from the network header or the tcp header.

[1]: https://lore.kernel.org/netdev/CANn89iLJNWh6bkH7DNhy_kmcAexuUCccqERqe7z2QsvPhGrYPQ@mail.gmail.com/

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20200820190123.2886935-1-kafai@fb.com

bpf: tcp: Allow bpf prog to write and parse TCP header option

[ Note: The TCP changes here is mainly to implement the bpf
pieces into the bpf_skops_*() functions introduced
in the earlier patches. ]

The earlier effort in BPF-TCP-CC allows the TCP Congestion Control
algorithm to be written in BPF. It opens up opportunities to allow
a faster turnaround time in testing/releasing new congestion control
ideas to production environment.

The same flexibility can be extended to writing TCP header option.
It is not uncommon that people want to test new TCP header option
to improve the TCP performance. Another use case is for data-center
that has a more controlled environment and has more flexibility in
putting header options for internal only use.

For example, we want to test the idea in putting maximum delay
ACK in TCP header option which is similar to a draft RFC proposal [1].

This patch introduces the necessary BPF API and use them in the
TCP stack to allow BPF_PROG_TYPE_SOCK_OPS program to parse
and write TCP header options. It currently supports most of
the TCP packet except RST.

Supported TCP header option:
───────────────────────────
This patch allows the bpf-prog to write any option kind.
Different bpf-progs can write its own option by calling the new helper
bpf_store_hdr_opt(). The helper will ensure there is no duplicated
option in the header.

By allowing bpf-prog to write any option kind, this gives a lot of
flexibility to the bpf-prog. Different bpf-prog can write its
own option kind. It could also allow the bpf-prog to support a
recently standardized option on an older kernel.

Sockops Callback Flags:
──────────────────────
The bpf program will only be called to parse/write tcp header option
if the following newly added callback flags are enabled
in tp->bpf_sock_ops_cb_flags:
BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG
BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG

A few words on the PARSE CB flags. When the above PARSE CB flags are
turned on, the bpf-prog will be called on packets received
at a sk that has at least reached the ESTABLISHED state.
The parsing of the SYN-SYNACK-ACK will be discussed in the
"3 Way HandShake" section.

The default is off for all of the above new CB flags, i.e. the bpf prog
will not be called to parse or write bpf hdr option. There are
details comment on these new cb flags in the UAPI bpf.h.

sock_ops->skb_data and bpf_load_hdr_opt()
─────────────────────────────────────────
sock_ops->skb_data and sock_ops->skb_data_end covers the whole
TCP header and its options. They are read only.

The new bpf_load_hdr_opt() helps to read a particular option "kind"
from the skb_data.

Please refer to the comment in UAPI bpf.h. It has details
on what skb_data contains under different sock_ops->op.

3 Way HandShake
───────────────
The bpf-prog can learn if it is sending SYN or SYNACK by reading the
sock_ops->skb_tcp_flags.

* Passive side

When writing SYNACK (i.e. sock_ops->op == BPF_SOCK_OPS_WRITE_HDR_OPT_CB),
the received SYN skb will be available to the bpf prog. The bpf prog can
use the SYN skb (which may carry the header option sent from the remote bpf
prog) to decide what bpf header option should be written to the outgoing
SYNACK skb. The SYN packet can be obtained by getsockopt(TCP_BPF_SYN*).
More on this later. Also, the bpf prog can learn if it is in syncookie
mode (by checking sock_ops->args[0] == BPF_WRITE_HDR_TCP_SYNACK_COOKIE).

The bpf prog can store the received SYN pkt by using the existing
bpf_setsockopt(TCP_SAVE_SYN). The example in a later patch does it.
[ Note that the fullsock here is a listen sk, bpf_sk_storage
is not very useful here since the listen sk will be shared
by many concurrent connection requests.

Extending bpf_sk_storage support to request_sock will add weight
to the minisock and it is not necessary better than storing the
whole ~100 bytes SYN pkt. ]

When the connection is established, the bpf prog will be called
in the existing PASSIVE_ESTABLISHED_CB callback. At that time,
the bpf prog can get the header option from the saved syn and
then apply the needed operation to the newly established socket.
The later patch will use the max delay ack specified in the SYN
header and set the RTO of this newly established connection
as an example.

The received ACK (that concludes the 3WHS) will also be available to
the bpf prog during PASSIVE_ESTABLISHED_CB through the sock_ops->skb_data.
It could be useful in syncookie scenario. More on this later.

There is an existing getsockopt "TCP_SAVED_SYN" to return the whole
saved syn pkt which includes the IP[46] header and the TCP header.
A few "TCP_BPF_SYN*" getsockopt has been added to allow specifying where to
start getting from, e.g. starting from TCP header, or from IP[46] header.

The new getsockopt(TCP_BPF_SYN*) will also know where it can get
the SYN's packet from:
- (a) the just received syn (available when the bpf prog is writing SYNACK)
and it is the only way to get SYN during syncookie mode.
or
- (b) the saved syn (available in PASSIVE_ESTABLISHED_CB and also other
existing CB).

The bpf prog does not need to know where the SYN pkt is coming from.
The getsockopt(TCP_BPF_SYN*) will hide this details.

Similarly, a flags "BPF_LOAD_HDR_OPT_TCP_SYN" is also added to
bpf_load_hdr_opt() to read a particular header option from the SYN packet.

* Fastopen

Fastopen should work the same as the regular non fastopen case.
This is a test in a later patch.

* Syncookie

For syncookie, the later example patch asks the active
side's bpf prog to resend the header options in ACK. The server
can use bpf_load_hdr_opt() to look at the options in this
received ACK during PASSIVE_ESTABLISHED_CB.

* Active side

The bpf prog will get a chance to write the bpf header option
in the SYN packet during WRITE_HDR_OPT_CB. The received SYNACK
pkt will also be available to the bpf prog during the existing
ACTIVE_ESTABLISHED_CB callback through the sock_ops->skb_data
and bpf_load_hdr_opt().

* Turn off header CB flags after 3WHS

If the bpf prog does not need to write/parse header options
beyond the 3WHS, the bpf prog can clear the bpf_sock_ops_cb_flags
to avoid being called for header options.
Or the bpf-prog can select to leave the UNKNOWN_HDR_OPT_CB_FLAG on
so that the kernel will only call it when there is option that
the kernel cannot handle.

[1]: draft-wang-tcpm-low-latency-opt-00
https://tools.ietf.org/html/draft-wang-tcpm-low-latency-opt-00

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190104.2885895-1-kafai@fb.com

bpf: sock_ops: Change some members of sock_ops_kern from u32 to u8

A later patch needs to add a few pointers and a few u8 to
sock_ops_kern. Hence, this patch saves some spaces by moving
some of the existing members from u32 to u8 so that the later
patch can still fit everything in a cacheline.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190058.2885640-1-kafai@fb.com

tcp: bpf: Add TCP_BPF_RTO_MIN for bpf_setsockopt

This patch adds bpf_setsockopt(TCP_BPF_RTO_MIN) to allow bpf prog
to set the min rto of a connection. It could be used together
with the earlier patch which has added bpf_setsockopt(TCP_BPF_DELACK_MAX).

A later selftest patch will communicate the max delay ack in a
bpf tcp header option and then the receiving side can use
bpf_setsockopt(TCP_BPF_RTO_MIN) to set a shorter rto.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200820190027.2884170-1-kafai@fb.com

tcp: bpf: Add TCP_BPF_DELACK_MAX setsockopt

This change is mostly from an internal patch and adapts it from sysctl
config to the bpf_setsockopt setup.

The bpf_prog can set the max delay ack by using
bpf_setsockopt(TCP_BPF_DELACK_MAX). This max delay ack can be communicated
to its peer through bpf header option. The receiving peer can then use
this max delay ack and set a potentially lower rto by using
bpf_setsockopt(TCP_BPF_RTO_MIN) which will be introduced
in the next patch.

Another later selftest patch will also use it like the above to show
how to write and parse bpf tcp header option.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200820190021.2884000-1-kafai@fb.com

tcp: Use a struct to represent a saved_syn

The TCP_SAVE_SYN has both the network header and tcp header.
The total length of the saved syn packet is currently stored in
the first 4 bytes (u32) of an array and the actual packet data is
stored after that.

A later patch will add a bpf helper that allows to get the tcp header
alone from the saved syn without the network header. It will be more
convenient to have a direct offset to a specific header instead of
re-parsing it. This requires to separately store the network hdrlen.
The total header length (i.e. network + tcp) is still needed for the
current usage in getsockopt. Although this total length can be obtained
by looking into the tcphdr and then get the (th->doff << 2), this patch
chooses to directly store the tcp hdrlen in the second four bytes of
this newly created "struct saved_syn". By using a new struct, it can
give a readable name to each individual header length.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200820190014.2883694-1-kafai@fb.com

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

bpf: sock_ops sk access may stomp registers when dst_reg = src_reg

Similar to patch ("bpf: sock_ops ctx access may stomp registers") if the
src_reg = dst_reg when reading the sk field of a sock_ops struct we
generate xlated code,

53: (61) r9 = *(u32 *)(r9 +28)
54: (15) if r9 == 0x0 goto pc+3
56: (79) r9 = *(u64 *)(r9 +0)

This stomps on the r9 reg to do the sk_fullsock check and then when
reading the skops->sk field instead of the sk pointer we get the
sk_fullsock. To fix use similar pattern noted in the previous fix
and use the temp field to save/restore a register used to do
sk_fullsock check.

After the fix the generated xlated code reads,

52: (7b) *(u64 *)(r9 +32) = r8
53: (61) r8 = *(u32 *)(r9 +28)
54: (15) if r9 == 0x0 goto pc+3
55: (79) r8 = *(u64 *)(r9 +32)
56: (79) r9 = *(u64 *)(r9 +0)
57: (05) goto pc+1
58: (79) r8 = *(u64 *)(r9 +32)

Here r9 register was in-use so r8 is chosen as the temporary register.
In line 52 r8 is saved in temp variable and at line 54 restored in case
fullsock != 0. Finally we handle fullsock == 0 case by restoring at
line 58.

This adds a new macro SOCK_OPS_GET_SK it is almost possible to merge
this with SOCK_OPS_GET_FIELD, but I found the extra branch logic a
bit more confusing than just adding a new macro despite a bit of
duplicating code.

Fixes: 1314ef561102e ("bpf: export bpf_sock for BPF_PROG_TYPE_SOCK_OPS prog type")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/159718349653.4728.6559437186853473612.stgit@john-Precision-5820-Tower