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tcp: Add listening address to SYN flood message

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The SYN flood message prints the listening port number, but with many
processes bound to the same port on different IPs, it's impossible to
tell which socket is the problem.

Add the listen IP address to the SYN flood message.

For IPv6 use "[IP]:port" as per RFC-5952 and to provide ease of
copy-paste to "ss" filters. For IPv4 use "IP:port" to match.

Each protcol's "any" address and a host address now look like:

 Possible SYN flooding on port 0.0.0.0:9001.
 Possible SYN flooding on port 127.0.0.1:9001.
 Possible SYN flooding on port [::]:9001.
 Possible SYN flooding on port [fc00::1]:9001.

Signed-off-by: Jamie Bainbridge <jamie.bainbridge@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Link: https://lore.kernel.org/r/4fedab7ce54a389aeadbdc639f6b4f4988e9d2d7.1668386107.git.jamie.bainbridge@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jamie Bainbridge 2022-11-14 12:00:08 +11:00 committed by Jakub Kicinski
parent feba6c6702
commit d9282e48c6
1 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
net/ipv4/tcp_input.c
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@ -6842,9 +6842,17 @@ static bool tcp_syn_flood_action(const struct sock *sk, const char *proto)
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
if (!queue->synflood_warned && syncookies != 2 &&
xchg(&queue->synflood_warned, 1) == 0)
net_info_ratelimited("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n",
proto, sk->sk_num, msg);
xchg(&queue->synflood_warned, 1) == 0) {
if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) {
net_info_ratelimited("%s: Possible SYN flooding on port [%pI6c]:%u. %s.\n",
proto, &sk->sk_v6_rcv_saddr,
sk->sk_num, msg);
} else {
net_info_ratelimited("%s: Possible SYN flooding on port %pI4:%u. %s.\n",
proto, &sk->sk_rcv_saddr,
sk->sk_num, msg);
}
}
return want_cookie;
}