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tcp: Fix bind() regression for v4-mapped-v6 non-wildcard address.

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Since bhash2 was introduced, the example below does not work as expected.
These two bind() should conflict, but the 2nd bind() now succeeds.

  from socket import *

  s1 = socket(AF_INET6, SOCK_STREAM)
  s1.bind(('::ffff:127.0.0.1', 0))

  s2 = socket(AF_INET, SOCK_STREAM)
  s2.bind(('127.0.0.1', s1.getsockname()[1]))

During the 2nd bind() in inet_csk_get_port(), inet_bind2_bucket_find()
fails to find the 1st socket's tb2, so inet_bind2_bucket_create() allocates
a new tb2 for the 2nd socket.  Then, we call inet_csk_bind_conflict() that
checks conflicts in the new tb2 by inet_bhash2_conflict().  However, the
new tb2 does not include the 1st socket, thus the bind() finally succeeds.

In this case, inet_bind2_bucket_match() must check if AF_INET6 tb2 has
the conflicting v4-mapped-v6 address so that inet_bind2_bucket_find()
returns the 1st socket's tb2.

Note that if we bind two sockets to 127.0.0.1 and then ::FFFF:127.0.0.1,
the 2nd bind() fails properly for the same reason mentinoed in the previous
commit.

Fixes: 28044fc1d4 ("net: Add a bhash2 table hashed by port and address")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima 2023-09-11 11:36:57 -07:00 committed by David S. Miller
parent aa99e5f87b
commit c48ef9c4ae
1 changed files with 6 additions and 1 deletions
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7
net/ipv4/inet_hashtables.c
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@ -820,8 +820,13 @@ static bool inet_bind2_bucket_match(const struct inet_bind2_bucket *tb,
return false;
#if IS_ENABLED(CONFIG_IPV6)
if (sk->sk_family != tb->family)
if (sk->sk_family != tb->family) {
if (sk->sk_family == AF_INET)
return ipv6_addr_v4mapped(&tb->v6_rcv_saddr) &&
tb->v6_rcv_saddr.s6_addr32[3] == sk->sk_rcv_saddr;
return false;
}
if (sk->sk_family == AF_INET6)
return ipv6_addr_equal(&tb->v6_rcv_saddr, &sk->sk_v6_rcv_saddr);