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

[ Upstream commit aa99e5f87bd54db55dd37cb130bd5eb55933027f ]

Andrei Vagin reported bind() regression with strace logs.

If we bind() a TCPv6 socket to ::FFFF:0.0.0.0 and then bind() a TCPv4
socket to 127.0.0.1, the 2nd bind() should fail but now succeeds.

  from socket import *

  s1 = socket(AF_INET6, SOCK_STREAM)
  s1.bind(('::ffff:0.0.0.0', 0))

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

During the 2nd bind(), if tb->family is AF_INET6 and sk->sk_family is
AF_INET in inet_bind2_bucket_match_addr_any(), we still need to check
if tb has the v4-mapped-v6 wildcard address.

The example above does not work after commit 5456262d2baa ("net: Fix
incorrect address comparison when searching for a bind2 bucket"), but
the blamed change is not the commit.

Before the commit, the leading zeros of ::FFFF:0.0.0.0 were treated
as 0.0.0.0, and the sequence above worked by chance.  Technically, this
case has been broken since bhash2 was introduced.

Note that if we bind() two sockets to 127.0.0.1 and then ::FFFF:0.0.0.0,
the 2nd bind() fails properly because we fall back to using bhash to
detect conflicts for the v4-mapped-v6 address.

Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address")
Reported-by: Andrei Vagin <avagin@google.com>
Closes: https://lore.kernel.org/netdev/ZPuYBOFC8zsK6r9T@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 8ced112167599a62633239b111d3d875d2fa99b8..517bdae78614bc9f2e70d776e21a5a6915212eb8 100644 (file)
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -750,6 +750,11 @@ static inline bool ipv6_addr_v4mapped(const struct in6_addr *a)
                                        cpu_to_be32(0x0000ffff))) == 0UL;
 }
 
+static inline bool ipv6_addr_v4mapped_any(const struct in6_addr *a)
+{
+       return ipv6_addr_v4mapped(a) && ipv4_is_zeronet(a->s6_addr32[3]);
+}
+
 static inline bool ipv6_addr_v4mapped_loopback(const struct in6_addr *a)
 {
        return ipv6_addr_v4mapped(a) && ipv4_is_loopback(a->s6_addr32[3]);

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 71d77b3b6536f167363feb98ba3328c447664a76..eb522c0374d5984080bfc0ce74e5e9fc853a4c19 100644 (file)
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -819,7 +819,8 @@ bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const
 #if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family != tb->family) {
                if (sk->sk_family == AF_INET)
-                       return ipv6_addr_any(&tb->v6_rcv_saddr);
+                       return ipv6_addr_any(&tb->v6_rcv_saddr) ||
+                               ipv6_addr_v4mapped_any(&tb->v6_rcv_saddr);
 
                return false;
        }