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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 <edumazet@google.com>
Link: https://lore.kernel.org/r/20230201174345.2708943-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-02-01 17:43:45 +00:00 committed by Jakub Kicinski
parent 0719bc3a5c
commit 2798e36dc2
3 changed files with 9 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/net/dropreason.h
View File

@ -71,6 +71,7 @@
FN(DUP_FRAG) \
FN(FRAG_REASM_TIMEOUT) \
FN(FRAG_TOO_FAR) \
FN(TCP_MINTTL) \
FNe(MAX)
/**
@ -312,6 +313,11 @@ enum skb_drop_reason {
* (/proc/sys/net/ipv4/ipfrag_max_dist)
*/
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'

1
net/ipv4/tcp_ipv4.c
View File

@ -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;
}
}

3
net/ipv6/tcp_ipv6.c
View File

@ -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;
}
}