From 26b46b13b81f5d0950fce1d38be1555d889b9079 Mon Sep 17 00:00:00 2001 From: Michal Kubecek Date: Mon, 9 May 2016 11:01:04 +0200 Subject: [PATCH] net: disable fragment reassembly if high_thresh is set to zero commit 30759219f562cfaaebe7b9c1d1c0e6b5445c69b0 upstream. Before commit 6d7b857d541e ("net: use lib/percpu_counter API for fragmentation mem accounting"), setting high threshold to 0 prevented fragment reassembly as first fragment would be always evicted before second could be added to the queue. While inefficient, some users apparently relied on it. Since the commit mentioned above, a percpu counter is used for reassembly memory accounting and high batch size avoids taking slow path in most common scenarios. As a result, a whole full sized packet can be reassembled without the percpu counter's main counter changing its value so that even with high_thresh set to 0, fragmented packets can be still reassembled and processed. Add explicit checks preventing reassembly if high threshold is zero. [mk] backport to 3.12 Signed-off-by: Michal Kubecek Signed-off-by: Jiri Slaby Signed-off-by: Willy Tarreau --- net/ipv4/ip_fragment.c | 4 ++++ net/ipv6/netfilter/nf_conntrack_reasm.c | 3 +++ net/ipv6/reassembly.c | 4 ++++ 3 files changed, 11 insertions(+) diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index 4d98a6b80b04..04c7e4618008 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -656,6 +656,9 @@ int ip_defrag(struct sk_buff *skb, u32 user) net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev); IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS); + if (!net->ipv4.frags.high_thresh) + goto fail; + /* Start by cleaning up the memory. */ ip_evictor(net); @@ -672,6 +675,7 @@ int ip_defrag(struct sk_buff *skb, u32 user) return ret; } +fail: IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); kfree_skb(skb); return -ENOMEM; diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index 7cd623588532..c11a40caf5b6 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -569,6 +569,9 @@ struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb, u32 user) if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0) return skb; + if (!net->nf_frag.frags.high_thresh) + return skb; + clone = skb_clone(skb, GFP_ATOMIC); if (clone == NULL) { pr_debug("Can't clone skb\n"); diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index a1fb511da3b5..1a5318efa31c 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -556,6 +556,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb) return 1; } + if (!net->ipv6.frags.high_thresh) + goto fail_mem; + evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags, false); if (evicted) IP6_ADD_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), @@ -575,6 +578,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb) return ret; } +fail_mem: IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS); kfree_skb(skb); return -1;