Hello, On Thu, 21 Aug 2014, Chris J Arges wrote: > A bug was reported against our kernel, which looks to be an upstream > issue after some testing (as of 3.17-rc1). > > In short, it seems that using ip_vs with something like dnsmasq-tftp to > send data will cause the transfer to stop at some point where the read > will error giving EPERM. It was discovered that CONFIG_IP_VS_IPV6 was > the change that introduce this difference in behavor. > > The bug report is here: > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1349768 ... > We've just recently enabled CONFIG_IP_VS_IPV6, which exposed this issue; > and the user is not using IPV6 functionality. > > I've traced through the code and found that this segment in > net/netfilter/ipvs/ip_vs_core.c > function ip_vs_out is what triggers this issue, if commented out the > problem does not occur: > > #ifdef CONFIG_IP_VS_IPV6 > if (af == AF_INET6) { > if (unlikely(iph.protocol == IPPROTO_ICMPV6)) { > int related; > int verdict = ip_vs_out_icmp_v6(skb, &related, > hooknum, &iph); > > if (related) > return verdict; > } > } else > #endif > > Printk'ing further into this, I see that ip_vs_out_icmp_v6 utimately > fails as frag_safe_skb_hp return NULL when packets are no longer being > sent with the test case. Looking at the stack trace in your bug report it is strange to see ip_vs_local_reply6 called by ip_local_out (v4). It can also explain the ipv6_find_hdr errors, we are providing IPv4 packet to IPv6 code... OK, found it, my fault: commit fc604767613b6d2036cdc35b660bc39451040a47 Author: Julian Anastasov <ja@xxxxxx> Date: Sun Oct 17 16:38:15 2010 +0300 ipvs: changes for local real server It is evident that ip_vs_local_reply6() is registered in PF_INET, not in PF_INET6. Later commit 4c809d630c17af0e8112d5362367ced9b44b009b renames it to NFPROTO_IPV4. > Any suggestions for a fix for this issue, or a places to continue > looking? I'd be happy to continue hacking on this and provide testing. IPPROTO_ICMPV6 is 58 (0x3A). Not sure how ipv6_find_hdr() finds it in some of the IPv4 packets, it is at offset 6 which is frag_off word in IPv4 header. In all other cases I think traffic is passed because it does not look like IPPROTO_ICMPV6. I think, it depends on IPPROTO_ICMPV6 being found in the header and the ipvsh->len which is again something wrong. Please, try this patch and report for result: [PATCH net] ipvs: fix ipv6 hook registration for local replies From: Julian Anastasov <ja@xxxxxx> commit fc604767613b6d2036cdc35b660bc39451040a47 ("ipvs: changes for local real server") from 2.6.37 introduced support for replies from local real server but the IPv6 handler ip_vs_local_reply6() is registered incorrectly as IPv4 hook leading to dropped traffic depending on IPv4 header values. Reported-by: Chris J Arges <chris.j.arges@xxxxxxxxxxxxx> Signed-off-by: Julian Anastasov <ja@xxxxxx> --- net/netfilter/ipvs/ip_vs_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c index e683675..5c34e8d 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -1906,7 +1906,7 @@ static struct nf_hook_ops ip_vs_ops[] __read_mostly = { { .hook = ip_vs_local_reply6, .owner = THIS_MODULE, - .pf = NFPROTO_IPV4, + .pf = NFPROTO_IPV6, .hooknum = NF_INET_LOCAL_OUT, .priority = NF_IP6_PRI_NAT_DST + 1, }, -- 1.9.0 Regards -- Julian Anastasov <ja@xxxxxx> -- To unsubscribe from this list: send the line "unsubscribe lvs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
