From a0d56cb911ca301de81735f1d73c2aab424654ba Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Sun, 2 Jun 2019 15:13:47 +0200 Subject: netfilter: ipv6: nf_defrag: fix leakage of unqueued fragments With commit 997dd9647164 ("net: IP6 defrag: use rbtrees in nf_conntrack_reasm.c"), nf_ct_frag6_reasm() is now called from nf_ct_frag6_queue(). With this change, nf_ct_frag6_queue() can fail after the skb has been added to the fragment queue and nf_ct_frag6_gather() was adapted to handle this case. But nf_ct_frag6_queue() can still fail before the fragment has been queued. nf_ct_frag6_gather() can't handle this case anymore, because it has no way to know if nf_ct_frag6_queue() queued the fragment before failing. If it didn't, the skb is lost as the error code is overwritten with -EINPROGRESS. Fix this by setting -EINPROGRESS directly in nf_ct_frag6_queue(), so that nf_ct_frag6_gather() can propagate the error as is. Fixes: 997dd9647164 ("net: IP6 defrag: use rbtrees in nf_conntrack_reasm.c") Signed-off-by: Guillaume Nault Signed-off-by: Pablo Neira Ayuso --- net/ipv6/netfilter/nf_conntrack_reasm.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'net/ipv6') diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index 3de0e9b0a482..5b3f65e29b6f 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -293,7 +293,11 @@ static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb, skb->_skb_refdst = 0UL; err = nf_ct_frag6_reasm(fq, skb, prev, dev); skb->_skb_refdst = orefdst; - return err; + + /* After queue has assumed skb ownership, only 0 or + * -EINPROGRESS must be returned. + */ + return err ? -EINPROGRESS : 0; } skb_dst_drop(skb); @@ -480,12 +484,6 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user) ret = 0; } - /* after queue has assumed skb ownership, only 0 or -EINPROGRESS - * must be returned. - */ - if (ret) - ret = -EINPROGRESS; - spin_unlock_bh(&fq->q.lock); inet_frag_put(&fq->q); return ret; -- cgit From 8a3dca632538c550930ce8bafa8c906b130d35cf Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Thu, 6 Jun 2019 18:04:00 +0200 Subject: netfilter: ipv6: nf_defrag: accept duplicate fragments again When fixing the skb leak introduced by the conversion to rbtree, I forgot about the special case of duplicate fragments. The condition under the 'insert_error' label isn't effective anymore as nf_ct_frg6_gather() doesn't override the returned value anymore. So duplicate fragments now get NF_DROP verdict. To accept duplicate fragments again, handle them specially as soon as inet_frag_queue_insert() reports them. Return -EINPROGRESS which will translate to NF_STOLEN verdict, like any accepted fragment. However, such packets don't carry any new information and aren't queued, so we just drop them immediately. Fixes: a0d56cb911ca ("netfilter: ipv6: nf_defrag: fix leakage of unqueued fragments") Signed-off-by: Guillaume Nault Signed-off-by: Pablo Neira Ayuso --- net/ipv6/netfilter/nf_conntrack_reasm.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'net/ipv6') diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index 5b3f65e29b6f..8951de8b568f 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -265,8 +265,14 @@ static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb, prev = fq->q.fragments_tail; err = inet_frag_queue_insert(&fq->q, skb, offset, end); - if (err) + if (err) { + if (err == IPFRAG_DUP) { + /* No error for duplicates, pretend they got queued. */ + kfree_skb(skb); + return -EINPROGRESS; + } goto insert_error; + } if (dev) fq->iif = dev->ifindex; @@ -304,8 +310,6 @@ static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb, return -EINPROGRESS; insert_error: - if (err == IPFRAG_DUP) - goto err; inet_frag_kill(&fq->q); err: skb_dst_drop(skb); -- cgit