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Date: Thu, 19 Apr 2007 14:06:17 +0900
From: Kazunori MIYAZAWA <kazunori@...azawa.org>
To: Diego Beltrami <Diego.Beltrami@...t.fi>
CC: netdev@...r.kernel.org, kaber@...sh.net,
herbert@...dor.apana.org.au, yoshfuji@...ux-ipv6.org, miika@....fi
Subject: Re: ESP interfamily tunnel bug?
Hello Diego,
I tried to reproduce the bug. But I got a panic of the kernel :-<
I'm using current net-2.6.
I suspect that some special routing for loopback is related
because I checked with kdb and got the backtrace like
fib_sync_down
ipv6_rcv
netif_receive_skb
__mod_timer
net_rx_action
__do_softirq
do_softirq
local_bh_enable
dev_queue_xmit
neigh_resolve_output
ip_output
xfrm4_output_finish
xfrm4_output
ip_generic_getfrag
ip6_push_pending_frames
I think ip_rcv or some IPv4 function should be called between netif_receive_skb
and ipv6_rcv.
Anyway I could not classify the way to make a panic.
I'll trace it.
Thank you,
Diego Beltrami wrote:
> Hi,
>
> we have discovered a routing related problem in ESP tunnel and beet mode.
> We don't know whether it is a bug in the XFRM, or just in the way the
> virtual addresses and the corresponding routes are set-up. We set up a
> dummy0 device for the virtual addresses:
>
> root@...ong:~# ip addr show dummy0
> 5: dummy0: <BROADCAST,NOARP,UP,10000> mtu 1500 qdisc noqueue
> link/ether 92:09:fe:11:81:1b brd ff:ff:ff:ff:ff:ff
> inet6 2001:72:e6d3:1cf3:e11d:5bb0:b99:e85e/28 scope global
> valid_lft forever preferred_lft forever
> inet6 2001:74:32e0:df36:e862:3963:523e:dd7d/28 scope global
> valid_lft forever preferred_lft forever
> inet6 2001:73:d3a8:8723:d572:7549:7f2c:e590/28 scope global
> valid_lft forever preferred_lft forever
> inet6 2001:75:a2e6:aad6:e901:dd1c:ba95:e300/28 scope global
> valid_lft forever preferred_lft forever
> inet6 fe80::9009:feff:fe11:811b/64 scope link
> valid_lft forever preferred_lft forever
>
> And then we have routes for the virtual addresses:
>
> root@...ong:~# ip -6 route
> 2001:72:e6d3:1cf3:e11d:5bb0:b99:e85e dev dummy0 metric 1024 expires
> 21334305sec mtu 1500 advmss 1440 metric 10 4294967295
> 2001:73:d3a8:8723:d572:7549:7f2c:e590 dev dummy0 metric 1024 expires
> 21334305sec mtu 1500 advmss 1440 metric 10 4294967295
> 2001:74:32e0:df36:e862:3963:523e:dd7d dev dummy0 metric 1024 expires
> 21334305sec mtu 1500 advmss 1440 metric 10 4294967295
> 2001:75:a2e6:aad6:e901:dd1c:ba95:e300 dev dummy0 metric 1024 expires
> 21334305sec mtu 1500 advmss 1440 metric 10 4294967295
> 2001:70::/28 dev dummy0 metric 256 expires 21334305sec mtu 1500 advmss
> 1440 metric 10 4294967295
> fe80::/64 dev dummy0 metric 256 expires 21334305sec mtu 1500 advmss 1440
> metric 10 4294967295
> ff00::/8 dev eth0 metric 256 expires 21325454sec mtu 1500 advmss 1440
> metric 10 4294967295
> ff00::/8 dev dummy0 metric 256 expires 21334305sec mtu 1500 advmss 1440
> metric 10 4294967295
> unreachable default dev lo proto none metric -1 error -101 metric 10
> 255
>
> ...and set-up policies and associations. The virtual IPv6 addresses
> are inner and IPv4 addresses are outer addresses:
>
> root@...ong:~/projects/hipl--userspace--2.6# ip xfrm policy show
> src 2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15/128 dst
> 2001:74:32e0:df36:e862:3963:523e:dd7d/128
> dir in priority 0
> tmpl src c1a7:bb82:: dst c0a8:65::
> proto esp reqid 0 mode beet
> src 2001:74:32e0:df36:e862:3963:523e:dd7d/128 dst
> 2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15/128
> dir out priority 0
> tmpl src c0a8:65:: dst c1a7:bb82::
> proto esp reqid 0 mode beet
>
> root@...ong:~/projects/hipl--userspace--2.6# ip xfrm state show
> src 193.167.187.130 dst 192.168.0.101
> proto esp spi 0xf556c7c7 reqid 0 mode beet
> replay-window 0
> auth sha1 0xab327b944011c94a0c54a097b4752e23f377ff34
> enc aes 0x882a334830b1cd14b9e411ec37a4242f
> encap type espinudp-nonike sport 50500 dport 50500
> addr 193.167.187.130
> sel src 2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15/0
> dst 2001:74:32e0:df36:e862:3963:523e:dd7d/0
> src 192.168.0.101 dst 193.167.187.130
> proto esp spi 0x1663f3a4 reqid 0 mode beet
> replay-window 0
> auth sha1 0x9f07dabce4abf2ebfe45e247ede2cf15f9156a13
> enc aes 0xfc50593b9af6d296b042a16ca00bad20
> encap type espinudp-nonike
> sport 50500 dport 50500 addr 192.168.0.101
> sel src 2001:74:32e0:df36:e862:3963:523e:dd7d/0
> dst 2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15/0
>
> And then we try to ping6 the virtual address:
>
> root@...ong:~/projects/hipl--userspace--2.6# ping6 -I
> 2001:0074:32e0:df36:e862:3963:523e:dd7d
> 2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15
> PING
> 2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15(2001:76:7d5a:88d7:51af:cdd1:6bf5:3d15)
> from 2001:74:32e0:df36:e862:3963:523e:dd7d : 56 data bytes
> ping: sendmsg: Network is unreachable
> ping: sendmsg: Network is unreachable
>
> Tcpdump shows no traffic at the host. We can repeat the problem both with
> tunnel and beet modes in 2.6.21-rc6 (and also in 2.6.17.14).
>
> I have tried also "ip rule stuff" but it seems that it does not rule with
> IPv6 :) It does help either to reduce the number of virtual addresses to a
> single one. It is weird that the ESP actually works some combinations of
> virtual addresses (4 of 16) in both directions, or works unidirectionally
> on some and does not work at all on the rest. I verified the
> unidirectional property using a simple UDP based application: sender xmits
> UDP packet, receiver gets it ok, but cannot respond. So, the problem is in
> the transmission of packets.
>
> I traced the ENETUNREACH in the kernel side to here:
>
> net/ipv4/route.c:ip_route_output_slow:
> if (fib_lookup(&fl, &res)) {
> ....
> if (dev_out)
> dev_put(dev_out);
> err = -ENETUNREACH;
>
> FIB lookup up is returning an error net/ipv4/fib_rules:
>
> int fib_lookup(const struct flowi *flp, struct fib_result *res)
> {
> ...
> hlist_for_each_entry_rcu(r, node, &fib_rules, hlist) {
> ...
> case RTN_UNREACHABLE:
> rcu_read_unlock();
> return -ENETUNREACH;
>
> I wonder if the problem is related to one that Yoshifugi has filed:
>
> http://bugzilla.kernel.org/show_bug.cgi?id=8349
>
> The bug does not usually occur with machines that in the same
> physical network, so I guess it is a routing problem. Any ideas or hints?
>
> Miika & Diego
>
>
>
>
>
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