[PATCH] TCP : use LIMIT_NETDEBUG in tcp_retransmit_timer()

[PATCH] TCP : use LIMIT_NETDEBUG in tcp_retransmit_timer()

[Eric Dumazet]

[-- Attachment #1: Type: text/plain, Size: 220 bytes --]

LIMIT_NETDEBUG allows the admin to disable some warning messages (echo 0 
 >/proc/sys/net/core/warnings).

The "TCP: Treason uncloaked!" message can use this facility.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>


[-- Attachment #2: use_limit_netdebug.patch --]
[-- Type: text/plain, Size: 688 bytes --]

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index e613401..e9b151b 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -292,9 +292,9 @@ static void tcp_retransmit_timer(struct 
 		 * we cannot allow such beasts to hang infinitely.
 		 */
 #ifdef TCP_DEBUG
-		if (net_ratelimit()) {
+		if (1) {
 			struct inet_sock *inet = inet_sk(sk);
-			printk(KERN_DEBUG "TCP: Treason uncloaked! Peer %u.%u.%u.%u:%u/%u shrinks window %u:%u. Repaired.\n",
+			LIMIT_NETDEBUG(KERN_DEBUG "TCP: Treason uncloaked! Peer %u.%u.%u.%u:%u/%u shrinks window %u:%u. Repaired.\n",
 			       NIPQUAD(inet->daddr), ntohs(inet->dport),
 			       inet->num, tp->snd_una, tp->snd_nxt);
 		}

Re: [PATCH] TCP : use LIMIT_NETDEBUG in tcp_retransmit_timer()

[David Miller]

From: Eric Dumazet <dada1@cosmosbay.com>
Date: Mon, 04 Jun 2007 09:13:40 +0200

> LIMIT_NETDEBUG allows the admin to disable some warning messages (echo 0 
>  >/proc/sys/net/core/warnings).
> 
> The "TCP: Treason uncloaked!" message can use this facility.
> 
> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>

That's pretty difficult to trigger remotely, and the last time
we saw a legitimate case of this it was actually a bug in the
Linux TCP stack which we've long since fixed.

I would rather not let people easily disable this, since it
finds bugs and I can't see someone seriously exploiting this
to spam your logs.

I suppose you disagree :)

Re: [PATCH] TCP : use LIMIT_NETDEBUG in tcp_retransmit_timer()

[Eric Dumazet]

David Miller a écrit :
> From: Eric Dumazet <dada1@cosmosbay.com>
> Date: Mon, 04 Jun 2007 09:13:40 +0200
> 
>> LIMIT_NETDEBUG allows the admin to disable some warning messages (echo 0 
>>  >/proc/sys/net/core/warnings).
>>
>> The "TCP: Treason uncloaked!" message can use this facility.
>>
>> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
> 
> That's pretty difficult to trigger remotely, and the last time
> we saw a legitimate case of this it was actually a bug in the
> Linux TCP stack which we've long since fixed.
> 
> I would rather not let people easily disable this, since it
> finds bugs and I can't see someone seriously exploiting this
> to spam your logs.
> 
> I suppose you disagree :)

Well, I dont know..

Should I try to contact 222.39.111.164 and kindly ask him not to trigger this 
annoying message ?

Is this remote peer running an old linux, or is it a bug in the current 
linux-2.6.22-rc4 kernel that my server runs ?

TCP: Treason uncloaked! Peer 222.39.111.164:3336/443 shrinks window 
768445619:768445688. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:1557/443 shrinks window 
979986676:979986745. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2819/443 shrinks window 
903113077:903113146. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2303/443 shrinks window 
919019510:919019579. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2689/443 shrinks window 
986306349:986306418. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2811/443 shrinks window 
1125084057:1125084126. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2394/443 shrinks window 
1141647532:1141647601. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2928/443 shrinks window 
1278301359:1278301428. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3034/443 shrinks window 
1408574195:1408574264. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2942/443 shrinks window 
1453238832:1453238901. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3384/443 shrinks window 
1883648213:1883648282. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3069/443 shrinks window 
1913770905:1913770974. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2852/443 shrinks window 
1956256538:1956256607. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3485/443 shrinks window 
2034019830:2034019899. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3104/443 shrinks window 
2054229702:2054229771. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2897/443 shrinks window 
2070392361:2070392430. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3485/443 shrinks window 
2034019830:2034019899. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3626/443 shrinks window 
2167403488:2167403557. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3104/443 shrinks window 
2054229702:2054229771. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2897/443 shrinks window 
2070392361:2070392430. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3626/443 shrinks window 
2167403488:2167403557. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2991/443 shrinks window 
2283637853:2283637922. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3128/443 shrinks window 
2283549171:2283549240. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2991/443 shrinks window 
2283637853:2283637922. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3128/443 shrinks window 
2283549171:2283549240. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:2991/443 shrinks window 
2283637853:2283637922. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3128/443 shrinks window 
2283549171:2283549240. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:4075/443 shrinks window 
2788112983:2788113052. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:4075/443 shrinks window 
2788112983:2788113052. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3786/443 shrinks window 
2905215394:2905215463. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:4075/443 shrinks window 
2788112983:2788113052. Repaired.
TCP: Treason uncloaked! Peer 222.39.111.164:3786/443 shrinks window 
2905215394:2905215463. Repaired.

Re: [PATCH] TCP : use LIMIT_NETDEBUG in tcp_retransmit_timer()

[David Miller]

From: Eric Dumazet <dada1@cosmosbay.com>
Date: Tue, 05 Jun 2007 09:07:26 +0200

> Should I try to contact 222.39.111.164 and kindly ask him not to trigger this 
> annoying message ?
> 
> Is this remote peer running an old linux, or is it a bug in the current 
> linux-2.6.22-rc4 kernel that my server runs ?

Grrr, yeah it's their end.  And because it's in China with no reverse
DNS your chances of getting them to fix this are between slim and
none.

I'll add your patch, thanks a lot.