netdev - [PATCH 04/13] netfilter: nf_flow_table: check ttl value in flow offload data path

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Message-Id: <20190513095630.32443-5-pablo@netfilter.org>
Date:   Mon, 13 May 2019 11:56:21 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 04/13] netfilter: nf_flow_table: check ttl value in flow offload data path

From: Taehee Yoo <ap420073@...il.com>

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@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.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;
-- 
2.11.0