ipv4: Set scope explicitly in ip_route_output().

Add a "scope" parameter to ip_route_output() so that callers don't have
to override the tos parameter with the RTO_ONLINK flag if they want a
local scope.

This will allow converting flowi4_tos to dscp_t in the future, thus
allowing static analysers to flag invalid interactions between
"tos" (the DSCP bits) and ECN.

Only three users ask for local scope (bonding, arp and atm). The others
continue to use RT_SCOPE_UNIVERSE. While there, add a comment to warn
users about the limitations of ip_route_output().

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Acked-by: Leon Romanovsky <leonro@nvidia.com> # infiniband
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 12 insertions, 7 deletions

diff --git a/net/atm/clip.c b/net/atm/clip.c
index 294cb9efe3d3..362e8d25a79e 100644
--- a/net/atm/clip.c
+++ b/net/atm/clip.c
@@ -463,7 +463,7 @@ static int clip_setentry(struct atm_vcc *vcc, __be32 ip)
 		unlink_clip_vcc(clip_vcc);
 		return 0;
 	}
-	rt = ip_route_output(&init_net, ip, 0, 1, 0);
+	rt = ip_route_output(&init_net, ip, 0, 0, 0, RT_SCOPE_LINK);
 	if (IS_ERR(rt))
 		return PTR_ERR(rt);
 	neigh = __neigh_lookup(&arp_tbl, &ip, rt->dst.dev, 1);
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 35e10c5a766d..4242447be322 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -399,7 +399,8 @@ static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_
 				goto free_skb;
 
 			rt = ip_route_output(net, iph->daddr, 0,
-					     RT_TOS(iph->tos), 0);
+					     RT_TOS(iph->tos), 0,
+					     RT_SCOPE_UNIVERSE);
 			if (!IS_ERR(rt)) {
 				/* - Bridged-and-DNAT'ed traffic doesn't
 				 *   require ip_forwarding. */
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 0d0d725b46ad..ab82ca104496 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -456,7 +456,8 @@ static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
 	/*unsigned long now; */
 	struct net *net = dev_net(dev);
 
-	rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
+	rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev),
+			     RT_SCOPE_UNIVERSE);
 	if (IS_ERR(rt))
 		return 1;
 	if (rt->dst.dev != dev) {
@@ -1056,7 +1057,8 @@ static int arp_req_set(struct net *net, struct arpreq *r,
 	if (r->arp_flags & ATF_PERM)
 		r->arp_flags |= ATF_COM;
 	if (!dev) {
-		struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
+		struct rtable *rt = ip_route_output(net, ip, 0, 0, 0,
+						    RT_SCOPE_LINK);
 
 		if (IS_ERR(rt))
 			return PTR_ERR(rt);
@@ -1188,7 +1190,8 @@ static int arp_req_delete(struct net *net, struct arpreq *r,
 
 	ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
 	if (!dev) {
-		struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
+		struct rtable *rt = ip_route_output(net, ip, 0, 0, 0,
+						    RT_SCOPE_LINK);
 		if (IS_ERR(rt))
 			return PTR_ERR(rt);
 		dev = rt->dst.dev;
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 717e97a389a8..9bf09de6a2e7 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1842,7 +1842,8 @@ static struct in_device *ip_mc_find_dev(struct net *net, struct ip_mreqn *imr)
 	if (!dev) {
 		struct rtable *rt = ip_route_output(net,
 						    imr->imr_multiaddr.s_addr,
-						    0, 0, 0);
+						    0, 0, 0,
+						    RT_SCOPE_UNIVERSE);
 		if (!IS_ERR(rt)) {
 			dev = rt->dst.dev;
 			ip_rt_put(rt);
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 6dab883a08dd..1303acb9cdd2 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -594,7 +594,7 @@ static struct net_device *inet_fib_lookup_dev(struct net *net,
 	struct in_addr daddr;
 
 	memcpy(&daddr, addr, sizeof(struct in_addr));
-	rt = ip_route_output(net, daddr.s_addr, 0, 0, 0);
+	rt = ip_route_output(net, daddr.s_addr, 0, 0, 0, RT_SCOPE_UNIVERSE);
 	if (IS_ERR(rt))
 		return ERR_CAST(rt);