From: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
To: linux-kernel@vger•kernel.org, netdev@vger•kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
stable@vger•kernel.org, Eric Dumazet <edumazet@google•com>,
"David S. Miller" <davem@davemloft•net>
Subject: [PATCH 4.9 55/71] inet: frags: do not clone skb in ip_expire()
Date: Tue, 16 Oct 2018 19:09:52 +0200 [thread overview]
Message-ID: <20181016170542.123827549@linuxfoundation.org> (raw)
In-Reply-To: <20181016170539.315587743@linuxfoundation.org>
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@google•com>
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>
(cherry picked from commit 1eec5d5670084ee644597bd26c25e22c69b9f748)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
---
net/ipv4/ip_fragment.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -141,8 +141,8 @@ static bool frag_expire_skip_icmp(u32 us
*/
static void ip_expire(unsigned long arg)
{
- struct sk_buff *clone, *head;
const struct iphdr *iph;
+ struct sk_buff *head;
struct net *net;
struct ipq *qp;
int err;
@@ -185,16 +185,12 @@ static void ip_expire(unsigned long arg)
(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:
next prev parent reply other threads:[~2018-10-16 17:09 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181016170539.315587743@linuxfoundation.org>
2018-10-16 17:09 ` [PATCH 4.9 43/71] inet: frags: change inet_frags_init_net() return value Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 44/71] inet: frags: add a pointer to struct netns_frags Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 45/71] inet: frags: refactor ipfrag_init() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 46/71] inet: frags: refactor ipv6_frag_init() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 47/71] inet: frags: refactor lowpan_net_frag_init() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 48/71] ipv6: export ip6 fragments sysctl to unprivileged users Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 49/71] rhashtable: add schedule points Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 50/71] inet: frags: use rhashtables for reassembly units Greg Kroah-Hartman
2018-10-26 13:39 ` Stefan Schmidt
2018-11-29 12:54 ` Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 51/71] inet: frags: remove some helpers Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 52/71] inet: frags: get rif of inet_frag_evicting() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 53/71] inet: frags: remove inet_frag_maybe_warn_overflow() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 54/71] inet: frags: break the 2GB limit for frags storage Greg Kroah-Hartman
2018-10-16 17:09 ` Greg Kroah-Hartman [this message]
2018-10-16 17:09 ` [PATCH 4.9 56/71] ipv6: frags: rewrite ip6_expire_frag_queue() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 57/71] rhashtable: reorganize struct rhashtable layout Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 58/71] inet: frags: reorganize struct netns_frags Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 59/71] inet: frags: get rid of ipfrag_skb_cb/FRAG_CB Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 60/71] inet: frags: fix ip6frag_low_thresh boundary Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 61/71] ip: discard IPv4 datagrams with overlapping segments Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 62/71] net: speed up skb_rbtree_purge() Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 63/71] net: modify skb_rbtree_purge to return the truesize of all purged skbs Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 64/71] ipv6: defrag: drop non-last frags smaller than min mtu Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 65/71] net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 66/71] net: add rb_to_skb() and other rb tree helpers Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 67/71] ip: use rb trees for IP frag queue Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 68/71] ip: add helpers to process in-order fragments faster Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 69/71] ip: process in-order fragments efficiently Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 70/71] ip: frags: fix crash in ip_do_fragment() Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 71/71] ipv4: frags: precedence bug in ip_expire() Greg Kroah-Hartman
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