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Message-ID: <20230201174345.2708943-1-edumazet@google.com>
Date: Wed, 1 Feb 2023 17:43:45 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] tcp: add TCP_MINTTL drop reason
In the unlikely case incoming packets are dropped because
of IP_MINTTL / IPV6_MINHOPCOUNT contraints...
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
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 70539288f9958716f9164cac3435cce34bd21f51..94bc3d5d880305a8c968a1801dabef83d995c567 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)
/**
@@ -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'
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 8320d0ecb13ae1e3e259f3c13a4c2797fbd984a5..ea370afa70ed979266dbeea474b034e833b15db4 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2102,6 +2102,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
/* 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 11b736a76bd7e46c8f521d5cfef74be5ae9deee0..543ee216772080d61800436a3eb31fa8d43d16c0 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1708,8 +1708,9 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
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;
}
}
--
2.39.1.456.gfc5497dd1b-goog
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