lwt: Fix return values of BPF xmit ops

BPF encap ops can return different types of positive values, such like
NET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function
skb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return
values would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in
ip(6)_finish_output2. When this happens, skbs that have been freed would
continue to the neighbor subsystem, causing use-after-free bug and
kernel crashes.

To fix the incorrect behavior, skb_do_redirect return values can be
simply discarded, the same as tc-egress behavior. On the other hand,
bpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU
information. Thus convert its return values to avoid the conflict with
LWTUNNEL_XMIT_CONTINUE.

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Reported-by: Jordan Griege <jgriege@cloudflare.com>
Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/0d2b878186cfe215fec6b45769c1cd0591d3628d.1692326837.git.yan@cloudflare.com

bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook

xmit_check_hhlen() observes the dst for getting the device hard header
length to make sure a modified packet can fit. When a helper which changes
the dst - such as bpf_skb_set_tunnel_key() - is called as part of the
xmit program the accessed dst is no longer valid.

This leads to the following splat:

BUG: kernel NULL pointer dereference, address: 00000000000000de
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 798 Comm: ping Not tainted 5.18.0-rc2+ #103
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
RIP: 0010:bpf_xmit+0xfb/0x17f
Code: c6 c0 4d cd 8e 48 c7 c7 7d 33 f0 8e e8 42 09 fb ff 48 8b 45 58 48 8b 95 c8 00 00 00 48 2b 95 c0 00 00 00 48 83 e0 fe 48 8b 00 <0f> b7 80 de 00 00 00 39 c2 73 22 29 d0 b9 20 0a 00 00 31 d2 48 89
RSP: 0018:ffffb148c0bc7b98 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000240008 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 00000000ffffffea RDI: 00000000ffffffff
RBP: ffff922a828a4e00 R08: ffffffff8f1350e8 R09: 00000000ffffdfff
R10: ffffffff8f055100 R11: ffffffff8f105100 R12: 0000000000000000
R13: ffff922a828a4e00 R14: 0000000000000040 R15: 0000000000000000
FS: 00007f414e8f0080(0000) GS:ffff922afdc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000000de CR3: 0000000002d80006 CR4: 0000000000370ef0
Call Trace:
<TASK>
lwtunnel_xmit.cold+0x71/0xc8
ip_finish_output2+0x279/0x520
? __ip_finish_output.part.0+0x21/0x130

Fix by fetching the device hard header length before running the BPF code.

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220420165219.1755407-1-eyal.birger@gmail.com

net: Don't include filter.h from net/sock.h

sock.h is pretty heavily used (5k objects rebuilt on x86 after
it's touched). We can drop the include of filter.h from it and
add a forward declaration of struct sk_filter instead.
This decreases the number of rebuilt objects when bpf.h
is touched from ~5k to ~1k.

There's a lot of missing includes this was masking. Primarily
in networking tho, this time.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org

lwt_bpf: Replace preempt_disable() with migrate_disable()

migrate_disable() is just a wrapper for preempt_disable() in
non-RT kernel. It is safe to replace it, and RT kernel will
benefit.

Note that it is introduced since Feb 2020.

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201205075946.497763-2-xiyou.wangcong@gmail.com

lwt: Disable BH too in run_lwt_bpf()

The per-cpu bpf_redirect_info is shared among all skb_do_redirect()
and BPF redirect helpers. Callers on RX path are all in BH context,
disabling preemption is not sufficient to prevent BH interruption.

In production, we observed strange packet drops because of the race
condition between LWT xmit and TC ingress, and we verified this issue
is fixed after we disable BH.

Although this bug was technically introduced from the beginning, that
is commit 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure"),
at that time call_rcu() had to be call_rcu_bh() to match the RCU context.
So this patch may not work well before RCU flavor consolidation has been
completed around v5.0.

Update the comments above the code too, as call_rcu() is now BH friendly.

Signed-off-by: Dongdong Wang <wangdongdong.6@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Link: https://lore.kernel.org/bpf/20201205075946.497763-1-xiyou.wangcong@gmail.com

net: add net available in build_state

The build_state callback of lwtunnel doesn't contain the net namespace
structure yet. This patch will add it so we can check on specific
address configuration at creation time of rpl source routes.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup

ipv6_stub uses the ip6_dst_lookup function to allow other modules to
perform IPv6 lookups. However, this function skips the XFRM layer
entirely.

All users of ipv6_stub->ip6_dst_lookup use ip_route_output_flow (via the
ip_route_output_key and ip_route_output helpers) for their IPv4 lookups,
which calls xfrm_lookup_route(). This patch fixes this inconsistent
behavior by switching the stub to ip6_dst_lookup_flow, which also calls
xfrm_lookup_route().

This requires some changes in all the callers, as these two functions
take different arguments and have different return types.

Fixes: 5f81bd2e5d80 ("ipv6: export a stub for IPv6 symbols used by vxlan")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: lwtunnel: Fix reroute supplying invalid dst

The dst in bpf_input() has lwtstate field set. As it is of the
LWTUNNEL_ENCAP_BPF type, lwtstate->data is struct bpf_lwt. When the bpf
program returns BPF_LWT_REROUTE, ip_route_input_noref is directly called on
this skb. This causes invalid memory access, as ip_route_input_slow calls
skb_tunnel_info(skb) that expects the dst->lwstate->data to be
struct ip_tunnel_info. This results to struct bpf_lwt being accessed as
struct ip_tunnel_info.

Drop the dst before calling the IP route input functions (both for IPv4 and
IPv6).

Reported by KASAN.

Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Oskolkov <posk@google.com>
Link: https://lore.kernel.org/bpf/111664d58fe4e9dd9c8014bb3d0b2dab93086a9e.1570609794.git.jbenc@redhat.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of version 2 of the gnu general public license as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 64 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

netlink: make validation more configurable for future strictness

We currently have two levels of strict validation:

1) liberal (default)
- undefined (type >= max) & NLA_UNSPEC attributes accepted
- attribute length >= expected accepted
- garbage at end of message accepted
2) strict (opt-in)
- NLA_UNSPEC attributes accepted
- attribute length >= expected accepted

Split out parsing strictness into four different options:
* TRAILING - check that there's no trailing data after parsing
attributes (in message or nested)
* MAXTYPE - reject attrs > max known type
* UNSPEC - reject attributes with NLA_UNSPEC policy entries
* STRICT_ATTRS - strictly validate attribute size

The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().

Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.

We end up with the following renames:
* nla_parse -> nla_parse_deprecated
* nla_parse_strict -> nla_parse_deprecated_strict
* nlmsg_parse -> nlmsg_parse_deprecated
* nlmsg_parse_strict -> nlmsg_parse_deprecated_strict
* nla_parse_nested -> nla_parse_nested_deprecated
* nla_validate_nested -> nla_validate_nested_deprecated

Using spatch, of course:
@@
expression TB, MAX, HEAD, LEN, POL, EXT;
@@
-nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
+nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

@@
expression TB, MAX, NLA, POL, EXT;
@@
-nla_parse_nested(TB, MAX, NLA, POL, EXT)
+nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

@@
expression START, MAX, POL, EXT;
@@
-nla_validate_nested(START, MAX, POL, EXT)
+nla_validate_nested_deprecated(START, MAX, POL, EXT)

@@
expression NLH, HDRLEN, MAX, POL, EXT;
@@
-nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
+nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.

Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.

Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.

In effect then, this adds fully strict validation for any new command.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: make nla_nest_start() add NLA_F_NESTED flag

Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.

Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().

Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:

@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)

@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: Move ipv6 stubs to a separate header file

The number of stubs is growing and has nothing to do with addrconf.
Move the definition of the stubs to a separate header file and update
users. In the move, drop the vxlan specific comment before ipv6_stub.

Code move only; no functional change intended.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: fix GSO in bpf_lwt_push_ip_encap

GSO needs inner headers and inner protocol set properly to work.

skb->inner_mac_header: skb_reset_inner_headers() assigns the current
mac header value to inner_mac_header; but it is not set at the point,
so we need to call skb_reset_inner_mac_header, otherwise gre_gso_segment
fails: it does

int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
...
if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
...

skb->inner_protocol should also be correctly set.

Fixes: ca78801a81e0 ("bpf: handle GSO in bpf_lwt_push_encap")
Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

net: fix double-free in bpf_lwt_xmit_reroute

dst_output() frees skb when it fails (see, for example,
ip_finish_output2), so it must not be freed in this case.

Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: fix memory leak in bpf_lwt_xmit_reroute

On error the skb should be freed. Tested with diff/steps
provided by David Ahern.

v2: surface routing errors to the user instead of a generic EINVAL,
as suggested by David Ahern.

Reported-by: David Ahern <dsahern@gmail.com>
Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c

This patch builds on top of the previous patch in the patchset,
which added BPF_LWT_ENCAP_IP mode to bpf_lwt_push_encap. As the
encapping can result in the skb needing to go via a different
interface/route/dst, bpf programs can indicate this by returning
BPF_LWT_REROUTE, which triggers a new route lookup for the skb.

v8 changes: fix kbuild errors when LWTUNNEL_BPF is builtin, but
IPV6 is a module: as LWTUNNEL_BPF can only be either Y or N,
call IPV6 routing functions only if they are built-in.

v9 changes:
- fixed a kbuild test robot compiler warning;
- call IPV6 routing functions via ipv6_stub.

v10 changes: removed unnecessary IS_ENABLED and pr_warn_once.

v11 changes: fixed a potential dst leak.

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: handle GSO in bpf_lwt_push_encap

This patch adds handling of GSO packets in bpf_lwt_push_ip_encap()
(called from bpf_lwt_push_encap):

* IPIP, GRE, and UDP encapsulation types are deduced by looking
into iphdr->protocol or ipv6hdr->next_header;
* SCTP GSO packets are not supported (as bpf_skb_proto_4_to_6
and similar do);
* UDP_L4 GSO packets are also not supported (although they are
not blocked in bpf_skb_proto_4_to_6 and similar), as
skb_decrease_gso_size() will break it;
* SKB_GSO_DODGY bit is set.

Note: it may be possible to support SCTP and UDP_L4 gso packets;
but as these cases seem to be not well handled by other
tunneling/encapping code paths, the solution should
be generic enough to apply to all tunneling/encapping code.

v8 changes:
- make sure that if GRE or UDP encap is detected, there is
enough of pushed bytes to cover both IP[v6] + GRE|UDP headers;
- do not reject double-encapped packets;
- whitelist TCP GSO packets rather than block SCTP GSO and
UDP GSO.

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap

Implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap BPF helper.
It enables BPF programs (specifically, BPF_PROG_TYPE_LWT_IN and
BPF_PROG_TYPE_LWT_XMIT prog types) to add IP encapsulation headers
to packets (e.g. IP/GRE, GUE, IPIP).

This is useful when thousands of different short-lived flows should be
encapped, each with different and dynamically determined destination.
Although lwtunnels can be used in some of these scenarios, the ability
to dynamically generate encap headers adds more flexibility, e.g.
when routing depends on the state of the host (reflected in global bpf
maps).

v7 changes:
- added a call skb_clear_hash();
- removed calls to skb_set_transport_header();
- refuse to encap GSO-enabled packets.

v8 changes:
- fix build errors when LWT is not enabled.

Note: the next patch in the patchset with deal with GSO-enabled packets,
which are currently rejected at encapping attempt.

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: in __bpf_redirect_no_mac pull mac only if present

Syzkaller was able to construct a packet of negative length by
redirecting from bpf_prog_test_run_skb with BPF_PROG_TYPE_LWT_XMIT:

BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:345 [inline]
BUG: KASAN: slab-out-of-bounds in skb_copy_from_linear_data include/linux/skbuff.h:3421 [inline]
BUG: KASAN: slab-out-of-bounds in __pskb_copy_fclone+0x2dd/0xeb0 net/core/skbuff.c:1395
Read of size 4294967282 at addr ffff8801d798009c by task syz-executor2/12942

kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
memcpy+0x23/0x50 mm/kasan/kasan.c:302
memcpy include/linux/string.h:345 [inline]
skb_copy_from_linear_data include/linux/skbuff.h:3421 [inline]
__pskb_copy_fclone+0x2dd/0xeb0 net/core/skbuff.c:1395
__pskb_copy include/linux/skbuff.h:1053 [inline]
pskb_copy include/linux/skbuff.h:2904 [inline]
skb_realloc_headroom+0xe7/0x120 net/core/skbuff.c:1539
ipip6_tunnel_xmit net/ipv6/sit.c:965 [inline]
sit_tunnel_xmit+0xe1b/0x30d0 net/ipv6/sit.c:1029
__netdev_start_xmit include/linux/netdevice.h:4325 [inline]
netdev_start_xmit include/linux/netdevice.h:4334 [inline]
xmit_one net/core/dev.c:3219 [inline]
dev_hard_start_xmit+0x295/0xc90 net/core/dev.c:3235
__dev_queue_xmit+0x2f0d/0x3950 net/core/dev.c:3805
dev_queue_xmit+0x17/0x20 net/core/dev.c:3838
__bpf_tx_skb net/core/filter.c:2016 [inline]
__bpf_redirect_common net/core/filter.c:2054 [inline]
__bpf_redirect+0x5cf/0xb20 net/core/filter.c:2061
____bpf_clone_redirect net/core/filter.c:2094 [inline]
bpf_clone_redirect+0x2f6/0x490 net/core/filter.c:2066
bpf_prog_41f2bcae09cd4ac3+0xb25/0x1000

The generated test constructs a packet with mac header, network
header, skb->data pointing to network header and skb->len 0.

Redirecting to a sit0 through __bpf_redirect_no_mac pulls the
mac length, even though skb->data already is at skb->network_header.
bpf_prog_test_run_skb has already pulled it as LWT_XMIT !is_l2.

Update the offset calculation to pull only if skb->data differs
from skb->network_header, which is not true in this case.

The test itself can be run only from commit 1cf1cae963c2 ("bpf:
introduce BPF_PROG_TEST_RUN command"), but the same type of packets
with skb at network header could already be built from lwt xmit hooks,
so this fix is more relevant to that commit.

Also set the mac header on redirect from LWT_XMIT, as even after this
change to __bpf_redirect_no_mac that field is expected to be set, but
is not yet in ip_finish_output2.

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

lwt_bpf: remove unnecessary rcu_read_lock in run_lwt_bpf

run_lwt_bpf is called by bpf_{input/output/xmit}.
These functions are already protected by rcu_read_lock.
because lwtunnel_{input/output/xmit} holds rcu_read_lock
and then calls bpf_{input/output/xmit}.
So that rcu_read_lock in the run_lwt_bpf is unnecessary.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

bpf: use GFP_ATOMIC instead of GFP_KERNEL in bpf_parse_prog()

bpf_parse_prog() is protected by rcu_read_lock().
so that GFP_KERNEL is not allowed in the bpf_parse_prog().

[51015.579396] =============================
[51015.579418] WARNING: suspicious RCU usage
[51015.579444] 4.18.0-rc6+ #208 Not tainted
[51015.579464] -----------------------------
[51015.579488] ./include/linux/rcupdate.h:303 Illegal context switch in RCU read-side critical section!
[51015.579510] other info that might help us debug this:
[51015.579532] rcu_scheduler_active = 2, debug_locks = 1
[51015.579556] 2 locks held by ip/1861:
[51015.579577] #0: 00000000a8c12fd1 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x2e0/0x910
[51015.579711] #1: 00000000bf815f8e (rcu_read_lock){....}, at: lwtunnel_build_state+0x96/0x390
[51015.579842] stack backtrace:
[51015.579869] CPU: 0 PID: 1861 Comm: ip Not tainted 4.18.0-rc6+ #208
[51015.579891] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015
[51015.579911] Call Trace:
[51015.579950] dump_stack+0x74/0xbb
[51015.580000] ___might_sleep+0x16b/0x3a0
[51015.580047] __kmalloc_track_caller+0x220/0x380
[51015.580077] kmemdup+0x1c/0x40
[51015.580077] bpf_parse_prog+0x10e/0x230
[51015.580164] ? kasan_kmalloc+0xa0/0xd0
[51015.580164] ? bpf_destroy_state+0x30/0x30
[51015.580164] ? bpf_build_state+0xe2/0x3e0
[51015.580164] bpf_build_state+0x1bb/0x3e0
[51015.580164] ? bpf_parse_prog+0x230/0x230
[51015.580164] ? lock_is_held_type+0x123/0x1a0
[51015.580164] lwtunnel_build_state+0x1aa/0x390
[51015.580164] fib_create_info+0x1579/0x33d0
[51015.580164] ? sched_clock_local+0xe2/0x150
[51015.580164] ? fib_info_update_nh_saddr+0x1f0/0x1f0
[51015.580164] ? sched_clock_local+0xe2/0x150
[51015.580164] fib_table_insert+0x201/0x1990
[51015.580164] ? lock_downgrade+0x610/0x610
[51015.580164] ? fib_table_lookup+0x1920/0x1920
[51015.580164] ? lwtunnel_valid_encap_type.part.6+0xcb/0x3a0
[51015.580164] ? rtm_to_fib_config+0x637/0xbd0
[51015.580164] inet_rtm_newroute+0xed/0x1b0
[51015.580164] ? rtm_to_fib_config+0xbd0/0xbd0
[51015.580164] rtnetlink_rcv_msg+0x331/0x910
[ ... ]

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

bpf: rename bpf_compute_data_end into bpf_compute_data_pointers

Just do the rename into bpf_compute_data_pointers() as we'll add
one more pointer here to recompute.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: add extack arg to lwtunnel build state

Pass extack arg down to lwtunnel_build_state and the build_state callbacks.
Add messages for failures in lwtunnel_build_state, and add the extarg to
nla_parse where possible in the build_state callbacks.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: pass extended ACK struct to parsing functions

Pass the new extended ACK reporting struct to all of the generic
netlink parsing functions. For now, pass NULL in almost all callers
(except for some in the core.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

lwtunnel: remove device arg to lwtunnel_build_state

Nothing about lwt state requires a device reference, so remove the
input argument.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Specify the owning module for lwtunnel ops

Modules implementing lwtunnel ops should not be allowed to unload
while there is state alive using those ops, so specify the owning
module for all lwtunnel ops.

Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

lwt_bpf: bpf_lwt_prog_cmp() can be static

Fixes the following sparse warning:

net/core/lwt_bpf.c:355:5: warning:
symbol 'bpf_lwt_prog_cmp' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: BPF for lightweight tunnel infrastructure

Registers new BPF program types which correspond to the LWT hooks:
- BPF_PROG_TYPE_LWT_IN => dst_input()
- BPF_PROG_TYPE_LWT_OUT => dst_output()
- BPF_PROG_TYPE_LWT_XMIT => lwtunnel_xmit()

The separate program types are required to differentiate between the
capabilities each LWT hook allows:

* Programs attached to dst_input() or dst_output() are restricted and
may only read the data of an skb. This prevent modification and
possible invalidation of already validated packet headers on receive
and the construction of illegal headers while the IP headers are
still being assembled.

* Programs attached to lwtunnel_xmit() are allowed to modify packet
content as well as prepending an L2 header via a newly introduced
helper bpf_skb_change_head(). This is safe as lwtunnel_xmit() is
invoked after the IP header has been assembled completely.

All BPF programs receive an skb with L3 headers attached and may return
one of the following error codes:

BPF_OK - Continue routing as per nexthop
BPF_DROP - Drop skb and return EPERM
BPF_REDIRECT - Redirect skb to device as per redirect() helper.
(Only valid in lwtunnel_xmit() context)

The return codes are binary compatible with their TC_ACT_
relatives to ease compatibility.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>