netdev - [PATCH v1 net 1/5] tcp: Fix bind() regression for v4-mapped-v6 wildcard address.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230911165106.39384-2-kuniyu@amazon.com>
Date: Mon, 11 Sep 2023 09:51:02 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, David Ahern <dsahern@...nel.org>
CC: Joanne Koong <joannelkoong@...il.com>, Kuniyuki Iwashima
	<kuniyu@...zon.com>, Kuniyuki Iwashima <kuni1840@...il.com>,
	<netdev@...r.kernel.org>, Andrei Vagin <avagin@...gle.com>
Subject: [PATCH v1 net 1/5] tcp: Fix bind() regression for v4-mapped-v6 wildcard address.

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@...gle.com>
Closes: https://lore.kernel.org/netdev/ZPuYBOFC8zsK6r9T@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 include/net/ipv6.h         | 5 +++++
 net/ipv4/inet_hashtables.c | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 0675be0f3fa0..56d8217ea6cf 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -784,6 +784,11 @@ 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 7876b7d703cb..0a9b20eb81c4 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -837,7 +837,8 @@ bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const
 		if (sk->sk_family == AF_INET)
 			return net_eq(ib2_net(tb), net) && tb->port == port &&
 				tb->l3mdev == l3mdev &&
-				ipv6_addr_any(&tb->v6_rcv_saddr);
+				(ipv6_addr_any(&tb->v6_rcv_saddr) ||
+				 ipv6_addr_v4mapped_any(&tb->v6_rcv_saddr));
 
 		return false;
 	}
-- 
2.30.2