[PATCH 5.1 077/155] netfilter: nf_flow_table: check ttl value in flow offload data path

Greg Kroah-Hartman
2019-06-13T16:03:27Z

[ Upstream commit 33cc3c0cfa64c86b6c4bbee86997aea638534931 ]

nf_flow_offload_ip_hook() and nf_flow_offload_ipv6_hook() do not check
ttl value. So, ttl value overflow may occur.

Fixes: 97add9f0d66d ("netfilter: flow table support for IPv4")
Fixes: 0995210753a2 ("netfilter: flow table support for IPv6")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_flow_table_ip.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
index 1d291a51cd45..46022a2867d7 100644
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -181,6 +181,9 @@ static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev,
iph->protocol != IPPROTO_UDP)
return -1;

+ if (iph->ttl <= 1)
+ return -1;
+
thoff = iph->ihl * 4;
if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
return -1;
@@ -411,6 +414,9 @@ static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
ip6h->nexthdr != IPPROTO_UDP)
return -1;

+ if (ip6h->hop_limit <= 1)
+ return -1;
+
thoff = sizeof(*ip6h);
if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
return -1;
--
2.20.1