| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.18 34/88] tcp: md5: fix IPv4-mapped support | Date | Mon, 1 Aug 2022 13:46:48 +0200 |
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From: Eric Dumazet <edumazet@google.com>
commit e62d2e110356093c034998e093675df83057e511 upstream.
After the blamed commit, IPv4 SYN packets handled by a dual stack IPv6 socket are dropped, even if perfectly valid.
$ nstat | grep MD5 TcpExtTCPMD5Failure 5 0.0
For a dual stack listener, an incoming IPv4 SYN packet would call tcp_inbound_md5_hash() with @family == AF_INET, while tp->af_specific is pointing to tcp_sock_ipv6_specific.
Only later when an IPv4-mapped child is created, tp->af_specific is changed to tcp_sock_ipv6_mapped_specific.
Fixes: 7bbb765b7349 ("net/tcp: Merge TCP-MD5 inbound callbacks") Reported-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Reviewed-by: Dmitry Safonov <dima@arista.com> Tested-by: Leonard Crestez <cdleonard@gmail.com> Link: https://lore.kernel.org/r/20220726115743.2759832-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/tcp.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
--- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4481,9 +4481,18 @@ tcp_inbound_md5_hash(const struct sock * return SKB_DROP_REASON_TCP_MD5UNEXPECTED; } - /* check the signature */ - genhash = tp->af_specific->calc_md5_hash(newhash, hash_expected, - NULL, skb); + /* Check the signature. + * To support dual stack listeners, we need to handle + * IPv4-mapped case. + */ + if (family == AF_INET) + genhash = tcp_v4_md5_hash_skb(newhash, + hash_expected, + NULL, skb); + else + genhash = tp->af_specific->calc_md5_hash(newhash, + hash_expected, + NULL, skb); if (genhash || memcmp(hash_location, newhash, 16) != 0) { NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
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