diff options
| author | Jiayuan Chen <jiayuan.chen@linux.dev> | 2025-04-09 19:26:04 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-04-10 18:29:26 -0700 |
| commit | 04271411121a58d37f47b065bc872f333274bf1f (patch) | |
| tree | 8a85309998c50f44d250ff91c2aa297156e038b7 /net/ipv4/tcp_minisocks.c | |
| parent | 709894c52c1cafa36fe2047ba5a0b83bdf398133 (diff) | |
tcp: add TCP_RFC7323_TW_PAWS drop reason
Devices in the networking path, such as firewalls, NATs, or routers, which
can perform SNAT or DNAT, use addresses from their own limited address
pools to masquerade the source address during forwarding, causing PAWS
verification to fail more easily.
Currently, packet loss statistics for PAWS can only be viewed through MIB,
which is a global metric and cannot be precisely obtained through tracing
to get the specific 4-tuple of the dropped packet. In the past, we had to
use kprobe ret to retrieve relevant skb information from
tcp_timewait_state_process().
We add a drop_reason pointer, similar to what previous commit does:
commit e34100c2ecbb ("tcp: add a drop_reason pointer to tcp_check_req()")
This commit addresses the PAWSESTABREJECTED case and also sets the
corresponding drop reason.
We use 'pwru' to test.
Before this commit:
''''
./pwru 'port 9999'
2025/04/07 13:40:19 Listening for events..
TUPLE FUNC
172.31.75.115:12345->172.31.75.114:9999(tcp) sk_skb_reason_drop(SKB_DROP_REASON_NOT_SPECIFIED)
'''
After this commit:
'''
./pwru 'port 9999'
2025/04/07 13:51:34 Listening for events..
TUPLE FUNC
172.31.75.115:12345->172.31.75.114:9999(tcp) sk_skb_reason_drop(SKB_DROP_REASON_TCP_RFC7323_TW_PAWS)
'''
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250409112614.16153-2-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_minisocks.c')
| -rw-r--r-- | net/ipv4/tcp_minisocks.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index fb9349be36b8..27511bf58c0f 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -97,7 +97,8 @@ static void twsk_rcv_nxt_update(struct tcp_timewait_sock *tcptw, u32 seq, */ enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, - const struct tcphdr *th, u32 *tw_isn) + const struct tcphdr *th, u32 *tw_isn, + enum skb_drop_reason *drop_reason) { struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); u32 rcv_nxt = READ_ONCE(tcptw->tw_rcv_nxt); @@ -245,8 +246,10 @@ kill: return TCP_TW_SYN; } - if (paws_reject) + if (paws_reject) { + *drop_reason = SKB_DROP_REASON_TCP_RFC7323_TW_PAWS; __NET_INC_STATS(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED); + } if (!th->rst) { /* In this case we must reset the TIMEWAIT timer. |