Re: PROBLEM: IPv6 TCP-Connections resetting

[Christoph Paasch <christoph.paasch@uclouvain.be>]

Hello,

On Saturday 06 April 2013 06:35:34 Hannes Frederic Sowa wrote:
> > [1.] One line summary of the problem:
> > 
> > IPv6 TCP-Connections resetting
> > 
> > [2.] Full description of the problem/report:
> > 
> > In the last weeks we updated some of our systems to a 3.8.4 Kernel.
> > Since then sometimes we can't connect to services running IPv6,
> > Apache and Openssh tested.
> > 
> > We got this on different machines with x86 and x86_64 Kernels. On
> > x86_64 it is more random, but on x86 i can reproduce it permanently
> > (Just opening any TCP Connection 1st time or after some short delay).
> > Connecting quick after the reset again will work as expected. It will
> > also work, if you keep another connection open.
> > 
> > Before I got to the Kernel, I just kept an strace on an userspace
> > process, but it did not notice the connection attempt. After this I
> > monitored the connection with tcpdump, but nothing unusual.
> > 
> > Then I did a rollback to the older Kernel and it worked as expected.
> > 
> > I tracked it down with 'git bisect' to commit:
> >   093d04d42fa094f6740bb188f0ad0c215ff61e2c
> > 
> > I also tested latest git state available.
> > 
> > [3.] Keywords (i.e., modules, networking, kernel):
> > 
> > networking, IPv6
> > 
> > [4.] Kernel information
> > 
> > [4.1.] Kernel version (from /proc/version):
> >   since commit: 093d04d42fa094f6740bb188f0ad0c215ff61e2c
> > 
> > [4.2.] Kernel .config file:
> > [5.] Most recent kernel version which did not have the bug:
> > 
> > none
> > 
> > [6.] Output of Oops.. message (if applicable) with symbolic information
> > 
> >      resolved (see Documentation/oops-tracing.txt)
> > 
> > [7.] A small shell script or example program which triggers the
> > 
> >      problem (if possible)
> > 
> > [8.] Environment
> > [8.1.] Software (add the output of the ver_linux script here)
> > 
> > Different systems, mostly reproduced on this one:
> > 
> > Linux dns03.tetja.de 3.9.0-rc5+ #10 SMP Fri Apr 5 16:55:54 CEST 2013
> > i686 AMD Athlon(tm) 64 X2 Dual Core Processor 5600+ AuthenticAMD
> > GNU/Linux
> > 
> > Gnu C                  4.4.5
> > Gnu make               3.82
> > binutils               2.22
> > util-linux             2.22.2
> > mount                  debug
> > module-init-tools      12
> > e2fsprogs              1.42
> > jfsutils               1.1.15
> > reiserfsprogs          3.6.21
> > xfsprogs               3.1.10
> > Linux C Library        2.15
> > Dynamic linker (ldd)   2.15
> > Procps                 3.3.4
> > Net-tools              1.60_p20120127084908
> > Kbd                    1.15.3wip
> > Sh-utils               8.20
> > Modules Loaded
> > 
> > Connections looking like this on booth sites:
> > 
> > 11:52:04.634315 IP6 2a00:1828:0:1::10.51808 >
> > 2a00:1828:1000:1102::2.80: Flags [S], seq 103067898, win 5760, options
> > [mss 1440,sackOK,TS val 232579708 ecr 0,nop,wscale 7], length 0
> > 
> > 11:52:04.634354 IP6 2a00:1828:1000:1102::2.80 >
> > 2a00:1828:0:1::10.51808: Flags [S.], seq 3352491415, ack 103067899, win
> > 14280, options [mss 1440,sackOK,TS val 174797959 ecr
> > 232579708,nop,wscale 7], length 0
> > 
> > 11:52:04.634656 IP6 fe80::92e2:baff:fe00:c120 > 2a00:1828:1000:1102::2:
> > ICMP6, redirect, 2a00:1828:0:1::10 to 2a00:1828:0:1::10, length 136
> > 
> > 11:52:04.634715 IP6 2a00:1828:0:1::10.51808 >
> > 2a00:1828:1000:1102::2.80: Flags [.], ack 1, win 45, options
> > [nop,nop,TS val 232579708 ecr 174797959], length 0
> > 
> > 11:52:04.634726 IP6 2a00:1828:1000:1102::2.80 >
> > 2a00:1828:0:1::10.51808: Flags [R], seq 3352491416, win 0, length 0
> > 
> > 11:52:04.635027 IP6 2a00:1828:0:1::10.51808 >
> > 2a00:1828:1000:1102::2.80: Flags [P.], seq 1:359, ack 1, win 45,
> > options [nop,nop,TS val 232579708 ecr 174797959], length 358
> > 
> > 11:52:04.635037 IP6 2a00:1828:1000:1102::2.80 >
> > 2a00:1828:0:1::10.51808: Flags [R], seq 3352491416, win 0, length 0
> > 
> > 11:52:04.635071 IP6 fe80::92e2:baff:fe00:c120 > 2a00:1828:1000:1102::2:
> > ICMP6, redirect, 2a00:1828:0:1::10 to 2a00:1828:0:1::10, length 112
> > 
> > 11:52:04.635246 IP6 fe80::92e2:baff:fe00:c120 > 2a00:1828:1000:1102::2:
> > ICMP6, redirect, 2a00:1828:0:1::10 to 2a00:1828:0:1::10, length 112

May it simply be a missing "goto out" in tcp_v6_err (see below patch) ?

Cheers,
Christoph

--------

From: Christoph Paasch <christoph.paasch@uclouvain.be>
Date: Sat, 6 Apr 2013 10:21:01 +0200
Subject: [PATCH] ipv6/tcp: Stop processing ICMPv6 redirect messages

Upon reception of an ICMPv6 Redirect message, we should not continue
inside tcp_v6_err. Otherwise, an error will be reported or request-socks
will be closed.

Adds also some parantheses to respect codingstyle guidelines.

Reported-by: Tetja Rediske <tetja@tetja.de>
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
---
 net/ipv6/tcp_ipv6.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 1033d2b..24434c5 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -386,6 +386,7 @@ static void tcp_v6_err(struct sk_buff *skb, struct 
inet6_skb_parm *opt,
 
 		if (dst)
 			dst->ops->redirect(dst, sk, skb);
+		goto out;
 	}
 
 	if (type == ICMPV6_PKT_TOOBIG) {
@@ -441,16 +442,18 @@ static void tcp_v6_err(struct sk_buff *skb, struct 
inet6_skb_parm *opt,
 			sk->sk_error_report(sk);		/* Wake people up to see the error 
(see connect in sock.c) */
 
 			tcp_done(sk);
-		} else
+		} else {
 			sk->sk_err_soft = err;
+		}
 		goto out;
 	}
 
 	if (!sock_owned_by_user(sk) && np->recverr) {
 		sk->sk_err = err;
 		sk->sk_error_report(sk);
-	} else
+	} else {
 		sk->sk_err_soft = err;
+	}
 
 out:
 	bh_unlock_sock(sk);
-- 
1.8.1.227.g44fe835




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