From 2798e36dc233a409a5d3f26f73029596dc504020 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 1 Feb 2023 17:43:45 +0000 Subject: [PATCH] tcp: add TCP_MINTTL drop reason In the unlikely case incoming packets are dropped because of IP_MINTTL / IPV6_MINHOPCOUNT constraints... Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20230201174345.2708943-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- include/net/dropreason.h | 6 ++++++ net/ipv4/tcp_ipv4.c | 1 + net/ipv6/tcp_ipv6.c | 3 ++- 3 files changed, 9 insertions(+), 1 deletion(-) diff --git a/include/net/dropreason.h b/include/net/dropreason.h index 70539288f995..94bc3d5d8803 100644 --- a/include/net/dropreason.h +++ b/include/net/dropreason.h @@ -71,6 +71,7 @@ FN(DUP_FRAG) \ FN(FRAG_REASM_TIMEOUT) \ FN(FRAG_TOO_FAR) \ + FN(TCP_MINTTL) \ FNe(MAX) /** @@ -313,6 +314,11 @@ enum skb_drop_reason { */ SKB_DROP_REASON_FRAG_TOO_FAR, /** + * @SKB_DROP_REASON_TCP_MINTTL: ipv4 ttl or ipv6 hoplimit below + * the threshold (IP_MINTTL or IPV6_MINHOPCOUNT). + */ + SKB_DROP_REASON_TCP_MINTTL, + /** * @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be * used as a real 'reason' */ diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 8320d0ecb13a..ea370afa70ed 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2102,6 +2102,7 @@ process: /* min_ttl can be changed concurrently from do_ip_setsockopt() */ if (unlikely(iph->ttl < READ_ONCE(inet_sk(sk)->min_ttl))) { __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP); + drop_reason = SKB_DROP_REASON_TCP_MINTTL; goto discard_and_relse; } } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 11b736a76bd7..543ee2167720 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1708,8 +1708,9 @@ process: if (static_branch_unlikely(&ip6_min_hopcount)) { /* min_hopcount can be changed concurrently from do_ipv6_setsockopt() */ - if (hdr->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount)) { + if (unlikely(hdr->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount))) { __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP); + drop_reason = SKB_DROP_REASON_TCP_MINTTL; goto discard_and_relse; } } -- 2.11.0