From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 1/4] netfilter: conntrack: fix false CRC32c mismatch using paged skb
Date: Mon, 29 May 2017 13:34:29 +0200 [thread overview]
Message-ID: <1496057672-6751-2-git-send-email-pablo@netfilter.org> (raw)
In-Reply-To: <1496057672-6751-1-git-send-email-pablo@netfilter.org>
From: Davide Caratti <dcaratti@redhat.com>
sctp_compute_cksum() implementation assumes that at least the SCTP header
is in the linear part of skb: modify conntrack error callback to avoid
false CRC32c mismatch, if the transport header is partially/entirely paged.
Fixes: cf6e007eef83 ("netfilter: conntrack: validate SCTP crc32c in PREROUTING")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nf_conntrack_proto_sctp.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
index 13875d599a85..1c5b14a6cab3 100644
--- a/net/netfilter/nf_conntrack_proto_sctp.c
+++ b/net/netfilter/nf_conntrack_proto_sctp.c
@@ -512,16 +512,19 @@ static int sctp_error(struct net *net, struct nf_conn *tpl, struct sk_buff *skb,
u8 pf, unsigned int hooknum)
{
const struct sctphdr *sh;
- struct sctphdr _sctph;
const char *logmsg;
- sh = skb_header_pointer(skb, dataoff, sizeof(_sctph), &_sctph);
- if (!sh) {
+ if (skb->len < dataoff + sizeof(struct sctphdr)) {
logmsg = "nf_ct_sctp: short packet ";
goto out_invalid;
}
if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
skb->ip_summed == CHECKSUM_NONE) {
+ if (!skb_make_writable(skb, dataoff + sizeof(struct sctphdr))) {
+ logmsg = "nf_ct_sctp: failed to read header ";
+ goto out_invalid;
+ }
+ sh = (const struct sctphdr *)(skb->data + dataoff);
if (sh->checksum != sctp_compute_cksum(skb, dataoff)) {
logmsg = "nf_ct_sctp: bad CRC ";
goto out_invalid;
--
2.1.4
next prev parent reply other threads:[~2017-05-29 11:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-29 11:34 [PATCH 0/4] Netfilter fixes for net Pablo Neira Ayuso
2017-05-29 11:34 ` Pablo Neira Ayuso [this message]
2017-05-29 11:34 ` [PATCH 2/4] netfilter: nft_set_rbtree: handle element re-addition after deletion Pablo Neira Ayuso
2017-05-29 11:34 ` [PATCH 3/4] netfilter: nat: use atomic bit op to clear the _SRC_NAT_DONE_BIT Pablo Neira Ayuso
2017-05-29 11:34 ` [PATCH 4/4] netfilter: ctnetlink: fix incorrect nf_ct_put during hash resize Pablo Neira Ayuso
2017-05-30 3:20 ` [PATCH 0/4] Netfilter fixes for net David Miller
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