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authorEric Dumazet <edumazet@google.com>2020-07-01 18:39:33 -0700
committerDavid S. Miller <davem@davemloft.net>2020-07-02 14:07:49 -0700
commit1ca0fafd73c5268e8fc4b997094b8bb2bfe8deea (patch)
tree44e4e277ed1b7f9c652cd673c9dfa0d88f8a8081 /net
parente4b9a72d76a47c11677b4bb0dee24a1fb6efb3e9 (diff)
downloadlinux-1ca0fafd73c5268e8fc4b997094b8bb2bfe8deea.tar.bz2
tcp: md5: allow changing MD5 keys in all socket states
This essentially reverts commit 721230326891 ("tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets") Mathieu reported that many vendors BGP implementations can actually switch TCP MD5 on established flows. Quoting Mathieu : Here is a list of a few network vendors along with their behavior with respect to TCP MD5: - Cisco: Allows for password to be changed, but within the hold-down timer (~180 seconds). - Juniper: When password is initially set on active connection it will reset, but after that any subsequent password changes no network resets. - Nokia: No notes on if they flap the tcp connection or not. - Ericsson/RedBack: Allows for 2 password (old/new) to co-exist until both sides are ok with new passwords. - Meta-Switch: Expects the password to be set before a connection is attempted, but no further info on whether they reset the TCP connection on a change. - Avaya: Disable the neighbor, then set password, then re-enable. - Zebos: Would normally allow the change when socket connected. We can revert my prior change because commit 9424e2e7ad93 ("tcp: md5: fix potential overestimation of TCP option space") removed the leak of 4 kernel bytes to the wire that was the main reason for my patch. While doing my investigations, I found a bug when a MD5 key is changed, leading to these commits that stable teams want to consider before backporting this revert : Commit 6a2febec338d ("tcp: md5: add missing memory barriers in tcp_md5_do_add()/tcp_md5_hash_key()") Commit e6ced831ef11 ("tcp: md5: refine tcp_md5_do_add()/tcp_md5_hash_key() barriers") Fixes: 721230326891 "tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets" Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c33f7c6aff8e..861fbd84c9cf 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3246,10 +3246,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
#ifdef CONFIG_TCP_MD5SIG
case TCP_MD5SIG:
case TCP_MD5SIG_EXT:
- if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))
- err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
- else
- err = -EINVAL;
+ err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
break;
#endif
case TCP_USER_TIMEOUT: