[NETFILTER]: Fix skb->nf_bridge lifetime issues (a193a4ab) · Commits · 戴 / test

The bridge netfilter code simulates the NF_IP_PRE_ROUTING hook and skips the real hook by registering with high priority and returning NF_STOP if skb->nf_bridge is present and the BRNF_NF_BRIDGE_PREROUTING flag is not set. The flag is only set during the simulated hook. Because skb->nf_bridge is only freed when the packet is destroyed, the packet will not only skip the first invocation of NF_IP_PRE_ROUTING, but in the case of tunnel devices on top of the bridge also all further ones. Forwarded packets from a bridge encapsulated by a tunnel device and sent as locally outgoing packet will also still have the incorrect bridge information from the input path attached. We already have nf_reset calls on all RX/TX paths of tunnel devices, so simply reset the nf_bridge field there too. As an added bonus, the bridge information for locally delivered packets is now also freed when the packet is queued to a socket. Signed-off-by:

Patrick McHardy <kaber@trash.net> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

+14 −10

Original line number	Diff line number	Diff line
		@@ -1351,16 +1351,6 @@ static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
		kfree_skb(skb);
		}
		#endif
		static inline void nf_reset(struct sk_buff *skb)
		{
		nf_conntrack_put(skb->nfct);
		skb->nfct = NULL;
		#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
		nf_conntrack_put_reasm(skb->nfct_reasm);
		skb->nfct_reasm = NULL;
		#endif
		}

		#ifdef CONFIG_BRIDGE_NETFILTER
		static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
		{
		@@ -1373,6 +1363,20 @@ static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
		atomic_inc(&nf_bridge->use);
		}
		#endif /* CONFIG_BRIDGE_NETFILTER */
		static inline void nf_reset(struct sk_buff *skb)
		{
		nf_conntrack_put(skb->nfct);
		skb->nfct = NULL;
		#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
		nf_conntrack_put_reasm(skb->nfct_reasm);
		skb->nfct_reasm = NULL;
		#endif
		#ifdef CONFIG_BRIDGE_NETFILTER
		nf_bridge_put(skb->nf_bridge);
		skb->nf_bridge = NULL;
		#endif
		}

		#else /* CONFIG_NETFILTER */
		static inline void nf_reset(struct sk_buff *skb) {}
		#endif /* CONFIG_NETFILTER */

net/ipv4/netfilter/ipt_REJECT.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -154,10 +154,6 @@ static void send_reset(struct sk_buff *oldskb, int hook)
		/* This packet will not be the same as the other: clear nf fields */
		nf_reset(nskb);
		nskb->nfmark = 0;
		#ifdef CONFIG_BRIDGE_NETFILTER
		nf_bridge_put(nskb->nf_bridge);
		nskb->nf_bridge = NULL;
		#endif

		tcph = (struct tcphdr )((u_int32_t)nskb->nh.iph + nskb->nh.iph->ihl);

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