ipv6: addrconf: fix /proc/net/if_inet6

Commit 1d5783030a1 (ipv6/addrconf: speedup /proc/net/if_inet6 filling)
added bugs hiding some devices from if_inet6 and breaking applications.

"ip -6 addr" could still display all IPv6 addresses, while "ifconfig -a"
couldnt.

One way to reproduce the bug is by starting in a shell :

unshare -n /bin/bash
ifconfig lo up

And in original net namespace, lo device disappeared from if_inet6

Reported-by: Jan Hinnerk Stosch <janhinnerk.stosch@gmail.com>
Tested-by: Jan Hinnerk Stosch <janhinnerk.stosch@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Mihai Maruseac <mihai.maruseac@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 6 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d7c56f8a5b4e..0424e4e27414 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3064,14 +3064,15 @@ static struct inet6_ifaddr *if6_get_first(struct seq_file *seq, loff_t pos)
                 struct hlist_node *n;
                 hlist_for_each_entry_rcu_bh(ifa, n, &inet6_addr_lst[state->bucket],
                                          addr_lst) {
+                        if (!net_eq(dev_net(ifa->idev->dev), net))
+                                continue;
                         /* sync with offset */
                         if (p < state->offset) {
                                 p++;
                                 continue;
                         }
                         state->offset++;
-                        if (net_eq(dev_net(ifa->idev->dev), net))
-                                return ifa;
+                        return ifa;
                 }
 
                 /* prepare for next bucket */
@@ -3089,18 +3090,20 @@ static struct inet6_ifaddr *if6_get_next(struct seq_file *seq,
         struct hlist_node *n = &ifa->addr_lst;
 
         hlist_for_each_entry_continue_rcu_bh(ifa, n, addr_lst) {
+                if (!net_eq(dev_net(ifa->idev->dev), net))
+                        continue;
                 state->offset++;
-                if (net_eq(dev_net(ifa->idev->dev), net))
-                        return ifa;
+                return ifa;
         }
 
         while (++state->bucket < IN6_ADDR_HSIZE) {
                 state->offset = 0;
                 hlist_for_each_entry_rcu_bh(ifa, n,
                                      &inet6_addr_lst[state->bucket], addr_lst) {
+                        if (!net_eq(dev_net(ifa->idev->dev), net))
+                                continue;
                         state->offset++;
-                        if (net_eq(dev_net(ifa->idev->dev), net))
-                                return ifa;
+                        return ifa;
                 }
         }