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authorPhil Oester <kernel@linuxace.com>2013-06-26 17:16:28 -0400
committerPablo Neira Ayuso <pablo@netfilter.org>2013-08-28 00:13:12 +0200
commitaffe759dbaa9e6c08b0da0a11d1933b61f199f51 (patch)
treef232ec8dcf549c3903b3a959480e79e9dba573c1 /net
parent35fdb94b453bc69b7bc74b717f1e03d41d4bcdba (diff)
downloadlinux-stericsson-affe759dbaa9e6c08b0da0a11d1933b61f199f51.tar.gz
netfilter: ip[6]t_REJECT: tcp-reset using wrong MAC source if bridged
As reported by Casper Gripenberg, in a bridged setup, using ip[6]t_REJECT with the tcp-reset option sends out reset packets with the src MAC address of the local bridge interface, instead of the MAC address of the intended destination. This causes some routers/firewalls to drop the reset packet as it appears to be spoofed. Fix this by bypassing ip[6]_local_out and setting the MAC of the sender in the tcp reset packet. This closes netfilter bugzilla #531. Signed-off-by: Phil Oester <kernel@linuxace.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/netfilter/ipt_REJECT.c21
-rw-r--r--net/ipv6/netfilter/ip6t_REJECT.c20
2 files changed, 39 insertions, 2 deletions
diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c
index 04b18c1ac345..b969131ad1c1 100644
--- a/net/ipv4/netfilter/ipt_REJECT.c
+++ b/net/ipv4/netfilter/ipt_REJECT.c
@@ -119,7 +119,26 @@ static void send_reset(struct sk_buff *oldskb, int hook)
nf_ct_attach(nskb, oldskb);
- ip_local_out(nskb);
+#ifdef CONFIG_BRIDGE_NETFILTER
+ /* If we use ip_local_out for bridged traffic, the MAC source on
+ * the RST will be ours, instead of the destination's. This confuses
+ * some routers/firewalls, and they drop the packet. So we need to
+ * build the eth header using the original destination's MAC as the
+ * source, and send the RST packet directly.
+ */
+ if (oldskb->nf_bridge) {
+ struct ethhdr *oeth = eth_hdr(oldskb);
+ nskb->dev = oldskb->nf_bridge->physindev;
+ niph->tot_len = htons(nskb->len);
+ ip_send_check(niph);
+ if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
+ oeth->h_source, oeth->h_dest, nskb->len) < 0)
+ goto free_nskb;
+ dev_queue_xmit(nskb);
+ } else
+#endif
+ ip_local_out(nskb);
+
return;
free_nskb:
diff --git a/net/ipv6/netfilter/ip6t_REJECT.c b/net/ipv6/netfilter/ip6t_REJECT.c
index 70f9abc0efe9..56eef30ee5f6 100644
--- a/net/ipv6/netfilter/ip6t_REJECT.c
+++ b/net/ipv6/netfilter/ip6t_REJECT.c
@@ -169,7 +169,25 @@ static void send_reset(struct net *net, struct sk_buff *oldskb)
nf_ct_attach(nskb, oldskb);
- ip6_local_out(nskb);
+#ifdef CONFIG_BRIDGE_NETFILTER
+ /* If we use ip6_local_out for bridged traffic, the MAC source on
+ * the RST will be ours, instead of the destination's. This confuses
+ * some routers/firewalls, and they drop the packet. So we need to
+ * build the eth header using the original destination's MAC as the
+ * source, and send the RST packet directly.
+ */
+ if (oldskb->nf_bridge) {
+ struct ethhdr *oeth = eth_hdr(oldskb);
+ nskb->dev = oldskb->nf_bridge->physindev;
+ nskb->protocol = htons(ETH_P_IPV6);
+ ip6h->payload_len = htons(sizeof(struct tcphdr));
+ if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
+ oeth->h_source, oeth->h_dest, nskb->len) < 0)
+ return;
+ dev_queue_xmit(nskb);
+ } else
+#endif
+ ip6_local_out(nskb);
}
static inline void