net/ipv6: Add support for specifying metric of connected routes

Add support for IFA_RT_PRIORITY to ipv6 addresses.

If the metric is changed on an existing address then the new route
is inserted before removing the old one. Since the metric is one
of the route keys, the prefix route can not be atomically replaced.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/addrconf.h

@@ -65,6 +65,7 @@ struct ifa6_config {
 
 	const struct in6_addr	*peer_pfx;
 
+	u32			rt_priority;
 	u32			ifa_flags;
 	u32			preferred_lft;
 	u32			valid_lft;

include/net/if_inet6.h

@@ -42,6 +42,7 @@ enum {
 struct inet6_ifaddr {
 	struct in6_addr		addr;
 	__u32			prefix_len;
+	__u32			rt_priority;
 
 	/* In seconds, relative to tstamp. Expiry is at tstamp + HZ * lft. */
 	__u32			valid_lft;

net/ipv6/addrconf.c

@@ -1056,6 +1056,7 @@ ipv6_add_addr(struct inet6_dev *idev, struct ifa6_config *cfg,
 	INIT_HLIST_NODE(&ifa->addr_lst);
 	ifa->scope = cfg->scope;
 	ifa->prefix_len = cfg->plen;
+	ifa->rt_priority = cfg->rt_priority;
 	ifa->flags = cfg->ifa_flags;
 	/* No need to add the TENTATIVE flag for addresses with NODAD */
 	if (!(cfg->ifa_flags & IFA_F_NODAD))
@@ -1356,6 +1357,7 @@ retry:
 
 	cfg.pfx = &addr;
 	cfg.scope = ipv6_addr_scope(cfg.pfx);
+	cfg.rt_priority = 0;
 
 	ift = ipv6_add_addr(idev, &cfg, block, NULL);
 	if (IS_ERR(ift)) {
@@ -2314,12 +2316,13 @@ static void  ipv6_try_regen_rndid(struct inet6_dev *idev, struct in6_addr *tmpad
  */
 
 static void
-addrconf_prefix_route(struct in6_addr *pfx, int plen, struct net_device *dev,
-		      unsigned long expires, u32 flags, gfp_t gfp_flags)
+addrconf_prefix_route(struct in6_addr *pfx, int plen, u32 metric,
+		      struct net_device *dev, unsigned long expires,
+		      u32 flags, gfp_t gfp_flags)
 {
 	struct fib6_config cfg = {
 		.fc_table = l3mdev_fib_table(dev) ? : RT6_TABLE_PREFIX,
-		.fc_metric = IP6_RT_PRIO_ADDRCONF,
+		.fc_metric = metric ? : IP6_RT_PRIO_ADDRCONF,
 		.fc_ifindex = dev->ifindex,
 		.fc_expires = expires,
 		.fc_dst_len = plen,
@@ -2683,7 +2686,8 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
 				expires = jiffies_to_clock_t(rt_expires);
 			}
 			addrconf_prefix_route(&pinfo->prefix, pinfo->prefix_len,
-					      dev, expires, flags, GFP_ATOMIC);
+					      0, dev, expires, flags,
+					      GFP_ATOMIC);
 		}
 		fib6_info_release(rt);
 	}
@@ -2891,8 +2895,9 @@ static int inet6_addr_add(struct net *net, int ifindex,
 	ifp = ipv6_add_addr(idev, cfg, true, extack);
 	if (!IS_ERR(ifp)) {
 		if (!(cfg->ifa_flags & IFA_F_NOPREFIXROUTE)) {
-			addrconf_prefix_route(&ifp->addr, ifp->prefix_len, dev,
-					      expires, flags, GFP_KERNEL);
+			addrconf_prefix_route(&ifp->addr, ifp->prefix_len,
+					      ifp->rt_priority, dev, expires,
+					      flags, GFP_KERNEL);
 		}
 
 		/* Send a netlink notification if DAD is enabled and
@@ -3056,7 +3061,7 @@ static void sit_add_v4_addrs(struct inet6_dev *idev)
 
 	if (addr.s6_addr32[3]) {
 		add_addr(idev, &addr, plen, scope);
-		addrconf_prefix_route(&addr, plen, idev->dev, 0, pflags,
+		addrconf_prefix_route(&addr, plen, 0, idev->dev, 0, pflags,
 				      GFP_ATOMIC);
 		return;
 	}
@@ -3081,8 +3086,8 @@ static void sit_add_v4_addrs(struct inet6_dev *idev)
 				}
 
 				add_addr(idev, &addr, plen, flag);
-				addrconf_prefix_route(&addr, plen, idev->dev, 0,
-						      pflags, GFP_ATOMIC);
+				addrconf_prefix_route(&addr, plen, 0, idev->dev,
+						      0, pflags, GFP_ATOMIC);
 			}
 		}
 	}
@@ -3128,7 +3133,7 @@ void addrconf_add_linklocal(struct inet6_dev *idev,
 
 	ifp = ipv6_add_addr(idev, &cfg, true, NULL);
 	if (!IS_ERR(ifp)) {
-		addrconf_prefix_route(&ifp->addr, ifp->prefix_len, idev->dev,
+		addrconf_prefix_route(&ifp->addr, ifp->prefix_len, 0, idev->dev,
 				      0, 0, GFP_ATOMIC);
 		addrconf_dad_start(ifp);
 		in6_ifa_put(ifp);
@@ -3244,7 +3249,7 @@ static void addrconf_addr_gen(struct inet6_dev *idev, bool prefix_route)
 			addrconf_add_linklocal(idev, &addr,
 					       IFA_F_STABLE_PRIVACY);
 		else if (prefix_route)
-			addrconf_prefix_route(&addr, 64, idev->dev,
+			addrconf_prefix_route(&addr, 64, 0, idev->dev,
 					      0, 0, GFP_KERNEL);
 		break;
 	case IN6_ADDR_GEN_MODE_EUI64:
@@ -3255,7 +3260,7 @@ static void addrconf_addr_gen(struct inet6_dev *idev, bool prefix_route)
 		if (ipv6_generate_eui64(addr.s6_addr + 8, idev->dev) == 0)
 			addrconf_add_linklocal(idev, &addr, 0);
 		else if (prefix_route)
-			addrconf_prefix_route(&addr, 64, idev->dev,
+			addrconf_prefix_route(&addr, 64, 0, idev->dev,
 					      0, 0, GFP_KERNEL);
 		break;
 	case IN6_ADDR_GEN_MODE_NONE:
@@ -3375,7 +3380,8 @@ static int fixup_permanent_addr(struct net *net,
 
 	if (!(ifp->flags & IFA_F_NOPREFIXROUTE)) {
 		addrconf_prefix_route(&ifp->addr, ifp->prefix_len,
-				      idev->dev, 0, 0, GFP_ATOMIC);
+				      ifp->rt_priority, idev->dev, 0, 0,
+				      GFP_ATOMIC);
 	}
 
 	if (ifp->state == INET6_IFADDR_STATE_PREDAD)
@@ -4495,6 +4501,7 @@ static const struct nla_policy ifa_ipv6_policy[IFA_MAX+1] = {
 	[IFA_LOCAL]		= { .len = sizeof(struct in6_addr) },
 	[IFA_CACHEINFO]		= { .len = sizeof(struct ifa_cacheinfo) },
 	[IFA_FLAGS]		= { .len = sizeof(u32) },
+	[IFA_RT_PRIORITY]	= { .len = sizeof(u32) },
 };
 
 static int
@@ -4527,6 +4534,37 @@ inet6_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 			      ifm->ifa_prefixlen);
 }
 
+static int modify_prefix_route(struct inet6_ifaddr *ifp,
+			       unsigned long expires, u32 flags)
+{
+	struct fib6_info *f6i;
+
+	f6i = addrconf_get_prefix_route(&ifp->addr,
+					ifp->prefix_len,
+					ifp->idev->dev,
+					0, RTF_GATEWAY | RTF_DEFAULT);
+	if (!f6i)
+		return -ENOENT;
+
+	if (f6i->fib6_metric != ifp->rt_priority) {
+		/* add new one */
+		addrconf_prefix_route(&ifp->addr, ifp->prefix_len,
+				      ifp->rt_priority, ifp->idev->dev,
+				      expires, flags, GFP_KERNEL);
+		/* delete old one */
+		ip6_del_rt(dev_net(ifp->idev->dev), f6i);
+	} else {
+		if (!expires)
+			fib6_clean_expires(f6i);
+		else
+			fib6_set_expires(f6i, expires);
+
+		fib6_info_release(f6i);
+	}
+
+	return 0;
+}
+
 static int inet6_addr_modify(struct inet6_ifaddr *ifp, struct ifa6_config *cfg)
 {
 	u32 flags;
@@ -4577,14 +4615,25 @@ static int inet6_addr_modify(struct inet6_ifaddr *ifp, struct ifa6_config *cfg)
 	ifp->valid_lft = cfg->valid_lft;
 	ifp->prefered_lft = cfg->preferred_lft;
 
+	if (cfg->rt_priority && cfg->rt_priority != ifp->rt_priority)
+		ifp->rt_priority = cfg->rt_priority;
+
 	spin_unlock_bh(&ifp->lock);
 	if (!(ifp->flags&IFA_F_TENTATIVE))
 		ipv6_ifa_notify(0, ifp);
 
 	if (!(cfg->ifa_flags & IFA_F_NOPREFIXROUTE)) {
-		addrconf_prefix_route(&ifp->addr, ifp->prefix_len,
-				      ifp->idev->dev, expires, flags,
-				      GFP_KERNEL);
+		int rc = -ENOENT;
+
+		if (had_prefixroute)
+			rc = modify_prefix_route(ifp, expires, flags);
+
+		/* prefix route could have been deleted; if so restore it */
+		if (rc == -ENOENT) {
+			addrconf_prefix_route(&ifp->addr, ifp->prefix_len,
+					      ifp->rt_priority, ifp->idev->dev,
+					      expires, flags, GFP_KERNEL);
+		}
 	} else if (had_prefixroute) {
 		enum cleanup_prefix_rt_t action;
 		unsigned long rt_expires;
@@ -4643,6 +4692,9 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	cfg.peer_pfx = peer_pfx;
 	cfg.plen = ifm->ifa_prefixlen;
+	if (tb[IFA_RT_PRIORITY])
+		cfg.rt_priority = nla_get_u32(tb[IFA_RT_PRIORITY]);
+
 	cfg.valid_lft = INFINITY_LIFE_TIME;
 	cfg.preferred_lft = INFINITY_LIFE_TIME;
 
@@ -4745,7 +4797,8 @@ static inline int inet6_ifaddr_msgsize(void)
 	       + nla_total_size(16) /* IFA_LOCAL */
 	       + nla_total_size(16) /* IFA_ADDRESS */
 	       + nla_total_size(sizeof(struct ifa_cacheinfo))
-	       + nla_total_size(4)  /* IFA_FLAGS */;
+	       + nla_total_size(4)  /* IFA_FLAGS */
+	       + nla_total_size(4)  /* IFA_RT_PRIORITY */;
 }
 
 static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
@@ -4791,6 +4844,10 @@ static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
 		if (nla_put_in6_addr(skb, IFA_ADDRESS, &ifa->addr) < 0)
 			goto error;
 
+	if (ifa->rt_priority &&
+	    nla_put_u32(skb, IFA_RT_PRIORITY, ifa->rt_priority))
+		goto error;
+
 	if (put_cacheinfo(skb, ifa->cstamp, ifa->tstamp, preferred, valid) < 0)
 		goto error;
 
@@ -5635,7 +5692,7 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
 		if (ifp->idev->cnf.forwarding)
 			addrconf_join_anycast(ifp);
 		if (!ipv6_addr_any(&ifp->peer_addr))
-			addrconf_prefix_route(&ifp->peer_addr, 128,
+			addrconf_prefix_route(&ifp->peer_addr, 128, 0,
 					      ifp->idev->dev, 0, 0,
 					      GFP_ATOMIC);
 		break;