lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 25 Oct 2012 17:05:43 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, alan@...rguk.ukuu.org.uk, Alexey Kuznetsov <kuznet@....inr.ac.ru> Subject: [ 35/42] tcp: resets are misrouted 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexey Kuznetsov <kuznet@....inr.ac.ru> [ Upstream commit 4c67525849e0b7f4bd4fab2487ec9e43ea52ef29 ] After commit e2446eaa ("tcp_v4_send_reset: binding oif to iif in no sock case").. tcp resets are always lost, when routing is asymmetric. Yes, backing out that patch will result in misrouting of resets for dead connections which used interface binding when were alive, but we actually cannot do anything here. What's died that's died and correct handling normal unbound connections is obviously a priority. Comment to comment: > This has few benefits: > 1. tcp_v6_send_reset already did that. It was done to route resets for IPv6 link local addresses. It was a mistake to do so for global addresses. The patch fixes this as well. Actually, the problem appears to be even more serious than guaranteed loss of resets. As reported by Sergey Soloviev <sol@....ru>, those misrouted resets create a lot of arp traffic and huge amount of unresolved arp entires putting down to knees NAT firewalls which use asymmetric routing. Signed-off-by: Alexey Kuznetsov <kuznet@....inr.ac.ru> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- net/ipv4/tcp_ipv4.c | 7 ++++--- net/ipv6/tcp_ipv6.c | 3 ++- 2 files changed, 6 insertions(+), 4 deletions(-) --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -678,10 +678,11 @@ static void tcp_v4_send_reset(struct soc arg.csumoffset = offsetof(struct tcphdr, check) / 2; arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0; /* When socket is gone, all binding information is lost. - * routing might fail in this case. using iif for oif to - * make sure we can deliver it + * routing might fail in this case. No choice here, if we choose to force + * input interface, we will misroute in case of asymmetric route. */ - arg.bound_dev_if = sk ? sk->sk_bound_dev_if : inet_iif(skb); + if (sk) + arg.bound_dev_if = sk->sk_bound_dev_if; net = dev_net(skb_dst(skb)->dev); arg.tos = ip_hdr(skb)->tos; --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -896,7 +896,8 @@ static void tcp_v6_send_response(struct __tcp_v6_send_check(buff, &fl6.saddr, &fl6.daddr); fl6.flowi6_proto = IPPROTO_TCP; - fl6.flowi6_oif = inet6_iif(skb); + if (ipv6_addr_type(&fl6.daddr) & IPV6_ADDR_LINKLOCAL) + fl6.flowi6_oif = inet6_iif(skb); fl6.fl6_dport = t1->dest; fl6.fl6_sport = t1->source; security_skb_classify_flow(skb, flowi6_to_flowi(&fl6)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists