1 files changed, 134 insertions, 43 deletions

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 0ee453fad3de..7527e94dd5dc 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -37,17 +37,16 @@
 #include <net/route.h>
 #include <net/netfilter/br_netfilter.h>
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#include <net/netfilter/nf_conntrack.h>
+#endif
+
 #include <asm/uaccess.h>
 #include "br_private.h"
 #ifdef CONFIG_SYSCTL
 #include <linux/sysctl.h>
 #endif
 
-#define skb_origaddr(skb)	 (((struct bridge_skb_cb *) \
-				 (skb->nf_bridge->data))->daddr.ipv4)
-#define store_orig_dstaddr(skb)	 (skb_origaddr(skb) = ip_hdr(skb)->daddr)
-#define dnat_took_place(skb)	 (skb_origaddr(skb) != ip_hdr(skb)->daddr)
-
 #ifdef CONFIG_SYSCTL
 static struct ctl_table_header *brnf_sysctl_header;
 static int brnf_call_iptables __read_mostly = 1;
@@ -154,6 +153,18 @@ static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 	return nf_bridge;
 }
 
+static unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __cpu_to_be16(ETH_P_8021Q):
+		return VLAN_HLEN;
+	case __cpu_to_be16(ETH_P_PPP_SES):
+		return PPPOE_SES_HLEN;
+	default:
+		return 0;
+	}
+}
+
 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 {
 	unsigned int len = nf_bridge_encap_header_len(skb);
@@ -239,6 +250,14 @@ drop:
 	return -1;
 }
 
+static void nf_bridge_update_protocol(struct sk_buff *skb)
+{
+	if (skb->nf_bridge->mask & BRNF_8021Q)
+		skb->protocol = htons(ETH_P_8021Q);
+	else if (skb->nf_bridge->mask & BRNF_PPPoE)
+		skb->protocol = htons(ETH_P_PPP_SES);
+}
+
 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 /* Undo the changes made for ip6tables PREROUTING and continue the
  * bridge PRE_ROUTING hook. */
@@ -314,6 +333,22 @@ free_skb:
 	return 0;
 }
 
+static bool dnat_took_place(const struct sk_buff *skb)
+{
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
+
+	ct = nf_ct_get(skb, &ctinfo);
+	if (!ct || nf_ct_is_untracked(ct))
+		return false;
+
+	return test_bit(IPS_DST_NAT_BIT, &ct->status);
+#else
+	return false;
+#endif
+}
+
 /* This requires some explaining. If DNAT has taken place,
  * we will need to fix up the destination Ethernet address.
  *
@@ -527,9 +562,7 @@ bad:
  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 static unsigned int br_nf_pre_routing_ipv6(const struct nf_hook_ops *ops,
 					   struct sk_buff *skb,
-					   const struct net_device *in,
-					   const struct net_device *out,
-					   int (*okfn)(struct sk_buff *))
+					   const struct nf_hook_state *state)
 {
 	const struct ipv6hdr *hdr;
 	u32 pkt_len;
@@ -577,9 +610,7 @@ static unsigned int br_nf_pre_routing_ipv6(const struct nf_hook_ops *ops,
  * address to be able to detect DNAT afterwards. */
 static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
 				      struct sk_buff *skb,
-				      const struct net_device *in,
-				      const struct net_device *out,
-				      int (*okfn)(struct sk_buff *))
+				      const struct nf_hook_state *state)
 {
 	struct net_bridge_port *p;
 	struct net_bridge *br;
@@ -588,7 +619,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
 	if (unlikely(!pskb_may_pull(skb, len)))
 		return NF_DROP;
 
-	p = br_port_get_rcu(in);
+	p = br_port_get_rcu(state->in);
 	if (p == NULL)
 		return NF_DROP;
 	br = p->br;
@@ -598,7 +629,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
 			return NF_ACCEPT;
 
 		nf_bridge_pull_encap_header_rcsum(skb);
-		return br_nf_pre_routing_ipv6(ops, skb, in, out, okfn);
+		return br_nf_pre_routing_ipv6(ops, skb, state);
 	}
 
 	if (!brnf_call_iptables && !br->nf_call_iptables)
@@ -617,7 +648,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
 		return NF_DROP;
 	if (!setup_pre_routing(skb))
 		return NF_DROP;
-	store_orig_dstaddr(skb);
+
 	skb->protocol = htons(ETH_P_IP);
 
 	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
@@ -636,9 +667,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
  * prevent this from happening. */
 static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
 				   struct sk_buff *skb,
-				   const struct net_device *in,
-				   const struct net_device *out,
-				   int (*okfn)(struct sk_buff *))
+				   const struct nf_hook_state *state)
 {
 	br_drop_fake_rtable(skb);
 	return NF_ACCEPT;
@@ -675,9 +704,7 @@ static int br_nf_forward_finish(struct sk_buff *skb)
  * bridge ports. */
 static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 				     struct sk_buff *skb,
-				     const struct net_device *in,
-				     const struct net_device *out,
-				     int (*okfn)(struct sk_buff *))
+				     const struct nf_hook_state *state)
 {
 	struct nf_bridge_info *nf_bridge;
 	struct net_device *parent;
@@ -691,7 +718,7 @@ static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 	if (!nf_bridge_unshare(skb))
 		return NF_DROP;
 
-	parent = bridge_parent(out);
+	parent = bridge_parent(state->out);
 	if (!parent)
 		return NF_DROP;
 
@@ -713,31 +740,27 @@ static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 	if (pf == NFPROTO_IPV4 && br_parse_ip_options(skb))
 		return NF_DROP;
 
-	/* The physdev module checks on this */
-	nf_bridge->mask |= BRNF_BRIDGED;
 	nf_bridge->physoutdev = skb->dev;
 	if (pf == NFPROTO_IPV4)
 		skb->protocol = htons(ETH_P_IP);
 	else
 		skb->protocol = htons(ETH_P_IPV6);
 
-	NF_HOOK(pf, NF_INET_FORWARD, skb, brnf_get_logical_dev(skb, in), parent,
-		br_nf_forward_finish);
+	NF_HOOK(pf, NF_INET_FORWARD, skb, brnf_get_logical_dev(skb, state->in),
+		parent,	br_nf_forward_finish);
 
 	return NF_STOLEN;
 }
 
 static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
 				      struct sk_buff *skb,
-				      const struct net_device *in,
-				      const struct net_device *out,
-				      int (*okfn)(struct sk_buff *))
+				      const struct nf_hook_state *state)
 {
 	struct net_bridge_port *p;
 	struct net_bridge *br;
 	struct net_device **d = (struct net_device **)(skb->cb);
 
-	p = br_port_get_rcu(out);
+	p = br_port_get_rcu(state->out);
 	if (p == NULL)
 		return NF_ACCEPT;
 	br = p->br;
@@ -756,31 +779,61 @@ static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
 			nf_bridge_push_encap_header(skb);
 		return NF_ACCEPT;
 	}
-	*d = (struct net_device *)in;
-	NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
-		(struct net_device *)out, br_nf_forward_finish);
+	*d = state->in;
+	NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, state->in,
+		state->out, br_nf_forward_finish);
 
 	return NF_STOLEN;
 }
 
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
+static bool nf_bridge_copy_header(struct sk_buff *skb)
+{
+	int err;
+	unsigned int header_size;
+
+	nf_bridge_update_protocol(skb);
+	header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
+	err = skb_cow_head(skb, header_size);
+	if (err)
+		return false;
+
+	skb_copy_to_linear_data_offset(skb, -header_size,
+				       skb->nf_bridge->data, header_size);
+	__skb_push(skb, nf_bridge_encap_header_len(skb));
+	return true;
+}
+
+static int br_nf_push_frag_xmit(struct sk_buff *skb)
+{
+	if (!nf_bridge_copy_header(skb)) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	return br_dev_queue_push_xmit(skb);
+}
+
 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 {
 	int ret;
 	int frag_max_size;
+	unsigned int mtu_reserved;
+
+	if (skb_is_gso(skb) || skb->protocol != htons(ETH_P_IP))
+		return br_dev_queue_push_xmit(skb);
 
+	mtu_reserved = nf_bridge_mtu_reduction(skb);
 	/* This is wrong! We should preserve the original fragment
 	 * boundaries by preserving frag_list rather than refragmenting.
 	 */
-	if (skb->protocol == htons(ETH_P_IP) &&
-	    skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
-	    !skb_is_gso(skb)) {
+	if (skb->len + mtu_reserved > skb->dev->mtu) {
 		frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
 		if (br_parse_ip_options(skb))
 			/* Drop invalid packet */
 			return NF_DROP;
 		IPCB(skb)->frag_max_size = frag_max_size;
-		ret = ip_fragment(skb, br_dev_queue_push_xmit);
+		ret = ip_fragment(skb, br_nf_push_frag_xmit);
 	} else
 		ret = br_dev_queue_push_xmit(skb);
 
@@ -796,15 +849,18 @@ static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 /* PF_BRIDGE/POST_ROUTING ********************************************/
 static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
 				       struct sk_buff *skb,
-				       const struct net_device *in,
-				       const struct net_device *out,
-				       int (*okfn)(struct sk_buff *))
+				       const struct nf_hook_state *state)
 {
 	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 	struct net_device *realoutdev = bridge_parent(skb->dev);
 	u_int8_t pf;
 
-	if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
+	/* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
+	 * on a bridge, but was delivered locally and is now being routed:
+	 *
+	 * POST_ROUTING was already invoked from the ip stack.
+	 */
+	if (!nf_bridge || !nf_bridge->physoutdev)
 		return NF_ACCEPT;
 
 	if (!realoutdev)
@@ -842,9 +898,7 @@ static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
  * for the second time. */
 static unsigned int ip_sabotage_in(const struct nf_hook_ops *ops,
 				   struct sk_buff *skb,
-				   const struct net_device *in,
-				   const struct net_device *out,
-				   int (*okfn)(struct sk_buff *))
+				   const struct nf_hook_state *state)
 {
 	if (skb->nf_bridge &&
 	    !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
@@ -854,6 +908,41 @@ static unsigned int ip_sabotage_in(const struct nf_hook_ops *ops,
 	return NF_ACCEPT;
 }
 
+/* This is called when br_netfilter has called into iptables/netfilter,
+ * and DNAT has taken place on a bridge-forwarded packet.
+ *
+ * neigh->output has created a new MAC header, with local br0 MAC
+ * as saddr.
+ *
+ * This restores the original MAC saddr of the bridged packet
+ * before invoking bridge forward logic to transmit the packet.
+ */
+static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
+{
+	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+
+	skb_pull(skb, ETH_HLEN);
+	nf_bridge->mask &= ~BRNF_BRIDGED_DNAT;
+
+	skb_copy_to_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN),
+				       skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
+	skb->dev = nf_bridge->physindev;
+	br_handle_frame_finish(skb);
+}
+
+static int br_nf_dev_xmit(struct sk_buff *skb)
+{
+	if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
+		br_nf_pre_routing_finish_bridge_slow(skb);
+		return 1;
+	}
+	return 0;
+}
+
+static const struct nf_br_ops br_ops = {
+	.br_dev_xmit_hook =	br_nf_dev_xmit,
+};
+
 void br_netfilter_enable(void)
 {
 }
@@ -991,12 +1080,14 @@ static int __init br_netfilter_init(void)
 		return -ENOMEM;
 	}
 #endif
+	RCU_INIT_POINTER(nf_br_ops, &br_ops);
 	printk(KERN_NOTICE "Bridge firewalling registered\n");
 	return 0;
 }
 
 static void __exit br_netfilter_fini(void)
 {
+	RCU_INIT_POINTER(nf_br_ops, NULL);
 	nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 #ifdef CONFIG_SYSCTL
 	unregister_net_sysctl_table(brnf_sysctl_header);