handshake: Fix sign of socket file descriptor fields

Socket file descriptors are signed integers. Use nla_get/put_s32 for
those to avoid implicit signed conversion in the netlink protocol.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/169530165057.8905.8650469415145814828.stgit@oracle-102.nfsv4bat.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: fix file ref count in handshake_nl_accept_doit()

If req->hr_proto->hp_accept() fail, we call fput() twice:
Once in the error path, but also a second time because sock->file
is at that point already associated with the file descriptor. Once
the task exits, as it would probably do after receiving an error
reading from netlink, the fd is closed, calling fput() a second time.

To fix, we move installing the file after the error path for the
hp_accept() call. In the case of errors we simply put the unused fd.
In case of success we can use fd_install() to link the sock->file
to the reserved fd.

Fixes: 7ea9c1ec66bc ("net/handshake: Fix handshake_dup() ref counting")
Signed-off-by: Moritz Wanzenböck <moritz.wanzenboeck@linbit.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20231019125847.276443-1-moritz.wanzenboeck@linbit.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: fix null-ptr-deref in handshake_nl_done_doit()

We should not call trace_handshake_cmd_done_err() if socket lookup has failed.

Also we should call trace_handshake_cmd_done_err() before releasing the file,
otherwise dereferencing sock->sk can return garbage.

This also reverts 7afc6d0a107f ("net/handshake: Fix uninitialized local variable")

Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5986 Comm: syz-executor292 Not tainted 6.5.0-rc7-syzkaller-gfe4469582053 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : handshake_nl_done_doit+0x198/0x9c8 net/handshake/netlink.c:193
lr : handshake_nl_done_doit+0x180/0x9c8
sp : ffff800096e37180
x29: ffff800096e37200 x28: 1ffff00012dc6e34 x27: dfff800000000000
x26: ffff800096e373d0 x25: 0000000000000000 x24: 00000000ffffffa8
x23: ffff800096e373f0 x22: 1ffff00012dc6e38 x21: 0000000000000000
x20: ffff800096e371c0 x19: 0000000000000018 x18: 0000000000000000
x17: 0000000000000000 x16: ffff800080516cc4 x15: 0000000000000001
x14: 1fffe0001b14aa3b x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000003
x8 : 0000000000000003 x7 : ffff800080afe47c x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080a88078
x2 : 0000000000000001 x1 : 00000000ffffffa8 x0 : 0000000000000000
Call trace:
handshake_nl_done_doit+0x198/0x9c8 net/handshake/netlink.c:193
genl_family_rcv_msg_doit net/netlink/genetlink.c:970 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:1050 [inline]
genl_rcv_msg+0x96c/0xc50 net/netlink/genetlink.c:1067
netlink_rcv_skb+0x214/0x3c4 net/netlink/af_netlink.c:2549
genl_rcv+0x38/0x50 net/netlink/genetlink.c:1078
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1914
sock_sendmsg_nosec net/socket.c:725 [inline]
sock_sendmsg net/socket.c:748 [inline]
____sys_sendmsg+0x56c/0x840 net/socket.c:2494
___sys_sendmsg net/socket.c:2548 [inline]
__sys_sendmsg+0x26c/0x33c net/socket.c:2577
__do_sys_sendmsg net/socket.c:2586 [inline]
__se_sys_sendmsg net/socket.c:2584 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2584
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
Code: 12800108 b90043e8 910062b3 d343fe68 (387b6908)

Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/handshake: handshake_genl_notify() shouldn't ignore @flags

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: Fix uninitialized local variable

trace_handshake_cmd_done_err() simply records the pointer in @req,
so initializing it to NULL is sufficient and safe.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: Fix handshake_dup() ref counting

If get_unused_fd_flags() fails, we ended up calling fput(sock->file)
twice.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: Remove unneeded check from handshake_dup()

handshake_req_submit() now verifies that the socket has a file.

Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: handshake_genl_notify() shouldn't ignore @flags

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/handshake: Fix uninitialized local variable

trace_handshake_cmd_done_err() simply records the pointer in @req,
so initializing it to NULL is sufficient and safe.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/handshake: Fix handshake_dup() ref counting

If get_unused_fd_flags() fails, we ended up calling fput(sock->file)
twice.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/handshake: Remove unneeded check from handshake_dup()

handshake_req_submit() now verifies that the socket has a file.

Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/handshake: Fix section mismatch in handshake_exit

If CONFIG_NET_NS=n (e.g. m68k/defconfig):

WARNING: modpost: vmlinux.o: section mismatch in reference: handshake_exit (section: .exit.text) -> handshake_genl_net_ops (section: .init.data)
ERROR: modpost: Section mismatches detected.

Fix this by dropping the __net_initdata tag from handshake_genl_net_ops.

Fixes: 3b3009ea8abb713b ("net/handshake: Create a NETLINK service for handling handshake requests")
Reported-by: noreply@ellerman.id.au
Closes: http://kisskb.ellerman.id.au/kisskb/buildresult/14912987
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20230420173723.3773434-1-geert@linux-m68k.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: Add Kunit tests for the handshake consumer API

These verify the API contracts and help exercise lifetime rules for
consumer sockets and handshake_req structures.

One way to run these tests:

./tools/testing/kunit/kunit.py run --kunitconfig ./net/handshake/.kunitconfig

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/handshake: Create a NETLINK service for handling handshake requests

When a kernel consumer needs a transport layer security session, it
first needs a handshake to negotiate and establish a session. This
negotiation can be done in user space via one of the several
existing library implementations, or it can be done in the kernel.

No in-kernel handshake implementations yet exist. In their absence,
we add a netlink service that can:

a. Notify a user space daemon that a handshake is needed.

b. Once notified, the daemon calls the kernel back via this
netlink service to get the handshake parameters, including an
open socket on which to establish the session.

c. Once the handshake is complete, the daemon reports the
session status and other information via a second netlink
operation. This operation marks that it is safe for the
kernel to use the open socket and the security session
established there.

The notification service uses a multicast group. Each handshake
mechanism (eg, tlshd) adopts its own group number so that the
handshake services are completely independent of one another. The
kernel can then tell via netlink_has_listeners() whether a handshake
service is active and prepared to handle a handshake request.

A new netlink operation, ACCEPT, acts like accept(2) in that it
instantiates a file descriptor in the user space daemon's fd table.
If this operation is successful, the reply carries the fd number,
which can be treated as an open and ready file descriptor.

While user space is performing the handshake, the kernel keeps its
muddy paws off the open socket. A second new netlink operation,
DONE, indicates that the user space daemon is finished with the
socket and it is safe for the kernel to use again. The operation
also indicates whether a session was established successfully.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>