[PATCH net-next 0/3] net: vrf: Fix ipv6 source address selection

@@ -18,6 +18,7 @@ struct route_info {
 	__u8			prefix[0];	/* 0,8 or 16 */
 };
 
+#include <net/addrconf.h>
 #include <net/flow.h>
 #include <net/ip6_fib.h>
 #include <net/sock.h>

@@ -88,9 +89,23 @@ int ip6_route_add(struct fib6_config *cfg);
 int ip6_ins_rt(struct rt6_info *);
 int ip6_del_rt(struct rt6_info *);
 
-int ip6_route_get_saddr(struct net *net, struct rt6_info *rt,
-			const struct in6_addr *daddr, unsigned int prefs,
-			struct in6_addr *saddr);
+static inline int ip6_route_get_saddr(struct net *net, struct rt6_info *rt,
+				      const struct in6_addr *daddr,
+				      unsigned int prefs,
+				      struct in6_addr *saddr)
+{
+	struct inet6_dev *idev =
+			rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
+	int err = 0;
+
+	if (rt && rt->rt6i_prefsrc.plen)
+		*saddr = rt->rt6i_prefsrc.addr;
+	else
+		err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
+					 daddr, prefs, saddr);
+
+	return err;
+}
 
 struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
 			    const struct in6_addr *saddr, int oif, int flags);

@@ -2586,23 +2586,6 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
 	return rt;
 }
 
-int ip6_route_get_saddr(struct net *net,
-			struct rt6_info *rt,
-			const struct in6_addr *daddr,
-			unsigned int prefs,
-			struct in6_addr *saddr)
-{
-	struct inet6_dev *idev =
-		rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
-	int err = 0;
-	if (rt && rt->rt6i_prefsrc.plen)
-		*saddr = rt->rt6i_prefsrc.addr;
-	else
-		err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
-					 daddr, prefs, saddr);
-	return err;
-}
-
 /* remove deleted ip from prefsrc entries */
 struct arg_dev_net_ip {
 	struct net_device *dev;

@@ -999,6 +999,46 @@ static struct dst_entry *vrf_get_rt6_dst(const struct net_device *dev,
 
 	return dst;
 }
+
+/* called under rcu_read_lock */
+static int vrf_get_saddr6(struct net_device *dev, const struct sock *sk,
+			  struct flowi6 *fl6)
+{
+	struct net *net = dev_net(dev);
+	struct dst_entry *dst;
+	struct rt6_info *rt;
+	int err;
+
+	if (rt6_need_strict(&fl6->daddr)) {
+		rt = vrf_ip6_route_lookup(net, dev, fl6, fl6->flowi6_oif,
+					  RT6_LOOKUP_F_IFACE);
+		if (unlikely(!rt))
+			return 0;
+
+		dst = &rt->dst;
+	} else {
+		__u8 flags = fl6->flowi6_flags;
+
+		fl6->flowi6_flags |= FLOWI_FLAG_L3MDEV_SRC;
+		fl6->flowi6_flags |= FLOWI_FLAG_SKIP_NH_OIF;
+
+		dst = ip6_route_output(net, sk, fl6);
+		rt = (struct rt6_info *)dst;
+
+		fl6->flowi6_flags = flags;
+	}
+
+	err = dst->error;
+	if (!err) {
+		err = ip6_route_get_saddr(net, rt, &fl6->daddr,
+					  sk ? inet6_sk(sk)->srcprefs : 0,
+					  &fl6->saddr);
+	}
+
+	dst_release(dst);
+
+	return err;
+}
 #endif
 
 static const struct l3mdev_ops vrf_l3mdev_ops = {

@@ -1008,6 +1048,7 @@ static const struct l3mdev_ops vrf_l3mdev_ops = {
 	.l3mdev_l3_rcv		= vrf_l3_rcv,
 #if IS_ENABLED(CONFIG_IPV6)
 	.l3mdev_get_rt6_dst	= vrf_get_rt6_dst,
+	.l3mdev_get_saddr6	= vrf_get_saddr6,
 #endif
 };
 

@@ -39,6 +39,9 @@ struct l3mdev_ops {
 	/* IPv6 ops */
 	struct dst_entry * (*l3mdev_get_rt6_dst)(const struct net_device *dev,
 						 struct flowi6 *fl6);
+	int		   (*l3mdev_get_saddr6)(struct net_device *dev,
+						const struct sock *sk,
+						struct flowi6 *fl6);
 };
 
 #ifdef CONFIG_NET_L3_MASTER_DEV

@@ -140,6 +143,8 @@ static inline bool netif_index_is_l3_master(struct net *net, int ifindex)
 int l3mdev_get_saddr(struct net *net, int ifindex, struct flowi4 *fl4);
 
 struct dst_entry *l3mdev_get_rt6_dst(struct net *net, struct flowi6 *fl6);
+int l3mdev_get_saddr6(struct net *net, const struct sock *sk,
+		      struct flowi6 *fl6);
 
 static inline
 struct sk_buff *l3mdev_l3_rcv(struct sk_buff *skb, u16 proto)

@@ -230,6 +235,12 @@ struct dst_entry *l3mdev_get_rt6_dst(struct net *net, struct flowi6 *fl6)
 	return NULL;
 }
 
+static inline int l3mdev_get_saddr6(struct net *net, const struct sock *sk,
+				    struct flowi6 *fl6)
+{
+	return 0;
+}
+
 static inline
 struct sk_buff *l3mdev_ip_rcv(struct sk_buff *skb)
 {

@@ -910,6 +910,13 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
 	int err;
 	int flags = 0;
 
+	if (ipv6_addr_any(&fl6->saddr) && fl6->flowi6_oif &&
+	    (!*dst || !(*dst)->error)) {
+		err = l3mdev_get_saddr6(net, sk, fl6);
+		if (err)
+			goto out_err;
+	}
+
 	/* The correct way to handle this would be to do
 	 * ip6_route_get_saddr, and then ip6_route_output; however,
 	 * the route-specific preferred source forces the

@@ -999,10 +1006,11 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
 	return 0;
 
 out_err_release:
-	if (err == -ENETUNREACH)
-		IP6_INC_STATS(net, NULL, IPSTATS_MIB_OUTNOROUTES);
 	dst_release(*dst);
 	*dst = NULL;
+out_err:
+	if (err == -ENETUNREACH)
+		IP6_INC_STATS(net, NULL, IPSTATS_MIB_OUTNOROUTES);
 	return err;
 }
 

@@ -162,6 +162,30 @@ int l3mdev_get_saddr(struct net *net, int ifindex, struct flowi4 *fl4)
 }
 EXPORT_SYMBOL_GPL(l3mdev_get_saddr);
 
+int l3mdev_get_saddr6(struct net *net, const struct sock *sk,
+		      struct flowi6 *fl6)
+{
+	struct net_device *dev;
+	int rc = 0;
+
+	if (fl6->flowi6_oif) {
+		rcu_read_lock();
+
+		dev = dev_get_by_index_rcu(net, fl6->flowi6_oif);
+		if (dev && netif_is_l3_slave(dev))
+			dev = netdev_master_upper_dev_get_rcu(dev);
+
+		if (dev && netif_is_l3_master(dev) &&
+		    dev->l3mdev_ops->l3mdev_get_saddr6)
+			rc = dev->l3mdev_ops->l3mdev_get_saddr6(dev, sk, fl6);
+
+		rcu_read_unlock();
+	}
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(l3mdev_get_saddr6);
+
 /**
  *	l3mdev_fib_rule_match - Determine if flowi references an
  *				L3 master device

@@ -79,6 +79,31 @@ static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
 	return rc;
 }
 
+static inline
+const struct net_device *l3mdev_master_dev_rcu(const struct net_device *_dev)
+{
+	/* netdev_master_upper_dev_get_rcu calls
+	 * list_first_or_null_rcu to walk the upper dev list.
+	 * list_first_or_null_rcu does not handle a const arg. We aren't
+	 * making changes, just want the master device from that list so
+	 * typecast to remove the const
+	 */
+	struct net_device *dev = (struct net_device *)_dev;
+	const struct net_device *master;
+
+	if (!dev)
+		return NULL;
+
+	if (netif_is_l3_master(dev))
+		master = dev;
+	else if (netif_is_l3_slave(dev))
+		master = netdev_master_upper_dev_get_rcu(dev);
+	else
+		master = NULL;
+
+	return master;
+}
+
 /* get index of an interface to use for FIB lookups. For devices
  * enslaved to an L3 master device FIB lookups are based on the
  * master index

@@ -190,6 +215,12 @@ static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
 	return 0;
 }
 
+static inline
+const struct net_device *l3mdev_master_dev_rcu(const struct net_device *dev)
+{
+	return NULL;
+}
+
 static inline int l3mdev_fib_oif_rcu(struct net_device *dev)
 {
 	return dev ? dev->ifindex : 0;

@@ -1524,6 +1524,28 @@ static int __ipv6_dev_get_saddr(struct net *net,
 	return hiscore_idx;
 }
 
+static int ipv6_get_saddr_master(struct net *net,
+				 const struct net_device *dst_dev,
+				 const struct net_device *master,
+				 struct ipv6_saddr_dst *dst,
+				 struct ipv6_saddr_score *scores,
+				 int hiscore_idx)
+{
+	struct inet6_dev *idev;
+
+	idev = __in6_dev_get(dst_dev);
+	if (idev)
+		hiscore_idx = __ipv6_dev_get_saddr(net, dst, idev,
+						   scores, hiscore_idx);
+
+	idev = __in6_dev_get(master);
+	if (idev)
+		hiscore_idx = __ipv6_dev_get_saddr(net, dst, idev,
+						   scores, hiscore_idx);
+
+	return hiscore_idx;
+}
+
 int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
 		       const struct in6_addr *daddr, unsigned int prefs,
 		       struct in6_addr *saddr)

@@ -1577,13 +1599,39 @@ int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
 		if (idev)
 			hiscore_idx = __ipv6_dev_get_saddr(net, &dst, idev, scores, hiscore_idx);
 	} else {
+		const struct net_device *master;
+		int master_idx = 0;
+
+		/* if dst_dev exists and is enslaved to an L3 device, then
+		 * prefer addresses from dst_dev and then the master over
+		 * any other enslaved devices in the L3 domain.
+		 */
+		master = l3mdev_master_dev_rcu(dst_dev);
+		if (master) {
+			master_idx = master->ifindex;
+
+			hiscore_idx = ipv6_get_saddr_master(net, dst_dev,
+							    master, &dst,
+							    scores, hiscore_idx);
+
+			if (scores[hiscore_idx].ifa)
+				goto out;
+		}
+
 		for_each_netdev_rcu(net, dev) {
+			/* only consider addresses on devices in the
+			 * same L3 domain
+			 */
+			if (l3mdev_master_ifindex_rcu(dev) != master_idx)
+				continue;
 			idev = __in6_dev_get(dev);
 			if (!idev)
 				continue;
 			hiscore_idx = __ipv6_dev_get_saddr(net, &dst, idev, scores, hiscore_idx);
 		}
 	}
+
+out:
 	rcu_read_unlock();
 
 	hiscore = &scores[hiscore_idx];