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authorEric Dumazet <edumazet@google.com>2018-03-31 12:58:54 -0700
committerDavid S. Miller <davem@davemloft.net>2018-03-31 23:25:39 -0400
commit1eec5d5670084ee644597bd26c25e22c69b9f748 (patch)
tree2b665adfd16baae97a8caa9426db3d168935a385 /net/ipv4/ip_fragment.c
parentinet: frags: break the 2GB limit for frags storage (diff)
downloadlinux-dev-1eec5d5670084ee644597bd26c25e22c69b9f748.tar.xz
linux-dev-1eec5d5670084ee644597bd26c25e22c69b9f748.zip
inet: frags: do not clone skb in ip_expire()
An skb_clone() was added in commit ec4fbd64751d ("inet: frag: release spinlock before calling icmp_send()") While fixing the bug at that time, it also added a very high cost for DDOS frags, as the ICMP rate limit is applied after this expensive operation (skb_clone() + consume_skb(), implying memory allocations, copy, and freeing) We can use skb_get(head) here, all we want is to make sure skb wont be freed by another cpu. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--net/ipv4/ip_fragment.c16
1 files changed, 6 insertions, 10 deletions
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 053869f2c49b..fb185d9a5cc7 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -143,8 +143,8 @@ static bool frag_expire_skip_icmp(u32 user)
static void ip_expire(struct timer_list *t)
{
struct inet_frag_queue *frag = from_timer(frag, t, timer);
- struct sk_buff *clone, *head;
const struct iphdr *iph;
+ struct sk_buff *head;
struct net *net;
struct ipq *qp;
int err;
@@ -187,16 +187,12 @@ static void ip_expire(struct timer_list *t)
(skb_rtable(head)->rt_type != RTN_LOCAL))
goto out;
- clone = skb_clone(head, GFP_ATOMIC);
+ skb_get(head);
+ spin_unlock(&qp->q.lock);
+ icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
+ kfree_skb(head);
+ goto out_rcu_unlock;
- /* Send an ICMP "Fragment Reassembly Timeout" message. */
- if (clone) {
- spin_unlock(&qp->q.lock);
- icmp_send(clone, ICMP_TIME_EXCEEDED,
- ICMP_EXC_FRAGTIME, 0);
- consume_skb(clone);
- goto out_rcu_unlock;
- }
out:
spin_unlock(&qp->q.lock);
out_rcu_unlock: