netfilter 04/05: fix crashes in bridge netfilter caused by fragment jumps

Patrick McHardy
2009-12-15T16:14:33Z

commit 8fa9ff6849bb86c59cc2ea9faadf3cb2d5223497
Author: Patrick McHardy <kaber@trash.net>
Date: Tue Dec 15 16:59:59 2009 +0100

netfilter: fix crashes in bridge netfilter caused by fragment jumps

When fragments from bridge netfilter are passed to IPv4 or IPv6 conntrack
and a reassembly queue with the same fragment key already exists from
reassembling a similar packet received on a different device (f.i. with
multicasted fragments), the reassembled packet might continue on a different
codepath than where the head fragment originated. This can cause crashes
in bridge netfilter when a fragment received on a non-bridge device (and
thus with skb->nf_bridge == NULL) continues through the bridge netfilter
code.

Add a new reassembly identifier for packets originating from bridge
netfilter and use it to put those packets in insolated queues.

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=14805

Reported-and-Tested-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/include/net/ip.h b/include/net/ip.h
index e6b9d12..85108cf 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -337,6 +337,7 @@ enum ip_defrag_users {
IP_DEFRAG_CALL_RA_CHAIN,
IP_DEFRAG_CONNTRACK_IN,
IP_DEFRAG_CONNTRACK_OUT,
+ IP_DEFRAG_CONNTRACK_BRIDGE_IN,
IP_DEFRAG_VS_IN,
IP_DEFRAG_VS_OUT,
IP_DEFRAG_VS_FWD
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index d691603..ccab594 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -354,6 +354,7 @@ enum ip6_defrag_users {
IP6_DEFRAG_LOCAL_DELIVER,
IP6_DEFRAG_CONNTRACK_IN,
IP6_DEFRAG_CONNTRACK_OUT,
+ IP6_DEFRAG_CONNTRACK_BRIDGE_IN,
};

struct ip6_create_arg {
diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
index fa2d6b6..331ead3 100644
--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -14,6 +14,7 @@
#include <net/route.h>
#include <net/ip.h>

+#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv4.h>
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>

@@ -34,6 +35,20 @@ static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
return err;
}

+static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
+ struct sk_buff *skb)
+{
+#ifdef CONFIG_BRIDGE_NETFILTER
+ if (skb->nf_bridge &&
+ skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
+ return IP_DEFRAG_CONNTRACK_BRIDGE_IN;
+#endif
+ if (hooknum == NF_INET_PRE_ROUTING)
+ return IP_DEFRAG_CONNTRACK_IN;
+ else
+ return IP_DEFRAG_CONNTRACK_OUT;
+}
+
static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
@@ -50,10 +65,8 @@ static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
#endif
/* Gather fragments. */
if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
- if (nf_ct_ipv4_gather_frags(skb,
- hooknum == NF_INET_PRE_ROUTING ?
- IP_DEFRAG_CONNTRACK_IN :
- IP_DEFRAG_CONNTRACK_OUT))
+ enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb);
+ if (nf_ct_ipv4_gather_frags(skb, user))
return NF_STOLEN;
}
return NF_ACCEPT;
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index c0a82fe..0956eba 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -20,6 +20,7 @@
#include <net/ipv6.h>
#include <net/inet_frag.h>

+#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv6.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
@@ -190,6 +191,11 @@ out:
static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
struct sk_buff *skb)
{
+#ifdef CONFIG_BRIDGE_NETFILTER
+ if (skb->nf_bridge &&
+ skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
+ return IP6_DEFRAG_CONNTRACK_BRIDGE_IN;
+#endif
if (hooknum == NF_INET_PRE_ROUTING)
return IP6_DEFRAG_CONNTRACK_IN;
else