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:
[EMAIL PROTECTED]:~# 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:
[EMAIL PROTECTED]:~# 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:
[EMAIL PROTECTED]:~/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
[EMAIL PROTECTED]:~/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:
[EMAIL PROTECTED]:~/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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