From 849a44de91636c24cea799cb8ad8c36433feb913 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Wed, 14 Jun 2017 13:27:37 +0200 Subject: [PATCH] net: don't global ICMP rate limit packets originating from loopback Florian Weimer seems to have a glibc test-case which requires that loopback interfaces does not get ICMP ratelimited. This was broken by commit c0303efeab73 ("net: reduce cycles spend on ICMP replies that gets rate limited"). An ICMP response will usually be routed back-out the same incoming interface. Thus, take advantage of this and skip global ICMP ratelimit when the incoming device is loopback. In the unlikely event that the outgoing it not loopback, due to strange routing policy rules, ICMP rate limiting still works via peer ratelimiting via icmpv4_xrlim_allow(). Thus, we should still comply with RFC1812 (section 4.3.2.8 "Rate Limiting"). This seems to fix the reproducer given by Florian. While still avoiding to perform expensive and unneeded outgoing route lookup for rate limited packets (in the non-loopback case). Fixes: c0303efeab73 ("net: reduce cycles spend on ICMP replies that gets rate limited") Reported-by: Florian Weimer Reported-by: "H.J. Lu" Signed-off-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- net/ipv4/icmp.c | 8 ++++++-- net/ipv6/icmp.c | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 43318b5f5647..9144fa7df2ad 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -657,8 +657,12 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) /* Needed by both icmp_global_allow and icmp_xmit_lock */ local_bh_disable(); - /* Check global sysctl_icmp_msgs_per_sec ratelimit */ - if (!icmpv4_global_allow(net, type, code)) + /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless + * incoming dev is loopback. If outgoing dev change to not be + * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) + */ + if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && + !icmpv4_global_allow(net, type, code)) goto out_bh_enable; sk = icmp_xmit_lock(net); diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index 230b5aac9f03..8d7b113958b1 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -491,7 +491,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, local_bh_disable(); /* Check global sysctl_icmp_msgs_per_sec ratelimit */ - if (!icmpv6_global_allow(type)) + if (!(skb->dev->flags&IFF_LOOPBACK) && !icmpv6_global_allow(type)) goto out_bh_enable; mip6_addr_swap(skb); -- GitLab