ipv4: fix confirm_addr_indev() when enable route_localnet

When arp_ignore=3, the NIC won't reply for scope host addresses, but
if enable route_locanet, we need to reply ip address with head 127 and
scope RT_SCOPE_HOST.

Fixes: d0daebc3d622 ("ipv4: Add interface option to enable routing of 127.0.0.0/8")

Signed-off-by: Shijie Luo <luoshijie1@huawei.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 2 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 6fd4628d10b9..7874303220c5 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1356,14 +1356,20 @@ EXPORT_SYMBOL(inet_select_addr);
 static __be32 confirm_addr_indev(struct in_device *in_dev, __be32 dst,
                               __be32 local, int scope)
 {
+        unsigned char localnet_scope = RT_SCOPE_HOST;
         const struct in_ifaddr *ifa;
         __be32 addr = 0;
         int same = 0;
 
+        if (unlikely(IN_DEV_ROUTE_LOCALNET(in_dev)))
+                localnet_scope = RT_SCOPE_LINK;
+
         in_dev_for_each_ifa_rcu(ifa, in_dev) {
+                unsigned char min_scope = min(ifa->ifa_scope, localnet_scope);
+
                 if (!addr &&
                     (local == ifa->ifa_local || !local) &&
-                    ifa->ifa_scope <= scope) {
+                    min_scope <= scope) {
                         addr = ifa->ifa_local;
                         if (same)
                                 break;
@@ -1378,7 +1384,7 @@ static __be32 confirm_addr_indev(struct in_device *in_dev, __be32 dst,
                                 if (inet_ifa_match(addr, ifa))
                                         break;
                                 /* No, then can we use new local src? */
-                                if (ifa->ifa_scope <= scope) {
+                                if (min_scope <= scope) {
                                         addr = ifa->ifa_local;
                                         break;
                                 }