bpf: tcp: Handle BPF SYN Cookie in cookie_v[46]_check().

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We will support arbitrary SYN Cookie with BPF in the following
patch.

If BPF prog validates ACK and kfunc allocates a reqsk, it will
be carried to cookie_[46]_check() as skb->sk.  If skb->sk is not
NULL, we call cookie_bpf_check().

Then, we clear skb->sk and skb->destructor, which are needed not
to hold refcnt for reqsk and the listener.  See the following patch
for details.

After that, we finish initialisation for the remaining fields with
cookie_tcp_reqsk_init().

Note that the server side WScale is set only for non-BPF SYN Cookie.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240115205514.68364-5-kuniyu@amazon.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

This commit is contained in:

Kuniyuki Iwashima 2024-01-15 12:55:12 -08:00 • committed by Alexei Starovoitov

parent 8b5ac68fb5

commit 695751e31a

3 changed files with 56 additions and 8 deletions

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20

include/net/tcp.h

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31

net/ipv4/syncookies.c

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13

net/ipv6/syncookies.c

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