io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6

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io_connect_bpf_populate() fills connect.port and connect.v6_addr for
AF_INET6 only when addr_len >= sizeof(struct sockaddr_in6), i.e. 28
bytes.

The IPv6 connect paths accept SIN6_LEN_RFC2133 (24 bytes), which
already holds sin6_port and sin6_addr. io_connect() passes addr_len to
the socket layer unchanged.

At addr_len 24 the filter sees family AF_INET6 with port and address
zero, while the kernel connects to the real destination. A filter that
denies an IPv6 port or address is bypassed. Denying connect.port == P
rejects [::1]:P with -EACCES at addr_len 28 but connects at addr_len 24.

Use SIN6_LEN_RFC2133 as the threshold. sin6_scope_id stays zero when
absent.

The threshold mismatch was found by an AI coding assistant (Claude Code)
comparing this hook against the net/ipv6 length checks on my
instructions; it also drafted the reproducer and this patch. I verified
the bypass and the fix in a VM on 7.3-rc6 and that 7.2 has the same
code.

Fixes: 899bea8248 ("io_uring/net: allow filtering on IORING_OP_CONNECT")
Cc: stable@vger.kernel.org # 7.2
Signed-off-by: Natasha Klaus <natalie.klaus@runtimeverification.com>
Link: https://patch.msgid.link/20261009133807.730724-1-natalie.klaus@runtimeverification.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

...

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Natasha Klaus 2026-10-09 16:38:07 +03:00 • committed by Jens Axboe

parent 6da8f402e3

commit aa5d5f8e50

1 changed files with 3 additions and 1 deletions

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io_uring/net.c

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