[PATCH net 08/12] ipv6: advertise IFLA_LINK_NETNSID when dumping ipv6 addresses

[Sabrina Dubroca]

Currently, we're not advertising link-netnsid when dumping IPv6
addresses, so the "ip -6 addr" command will not correctly interpret
the value of the IFLA_LINK attribute.

For example, we'll get:
    9: macvlan0@macvlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP 
qlen 1000
        <snip>

Instead of:
    9: macvlan0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 
1000 link-netns main
        <snip>

ndisc_ifinfo_sysctl_change calls inet6_fill_ifinfo without rcu or
rtnl, so I'm adding rcu_read_lock around rtnl_fill_link_netnsid.

Signed-off-by: Sabrina Dubroca <s...@queasysnail.net>
---
 net/ipv6/addrconf.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 688e441a8699..fb95c0227dfe 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5533,6 +5533,7 @@ static inline size_t inet6_if_nlmsg_size(void)
               + nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */
               + nla_total_size(4) /* IFLA_MTU */
               + nla_total_size(4) /* IFLA_LINK */
+              + nla_total_size(4) /* IFLA_LINK_NETNSID */
               + nla_total_size(1) /* IFLA_OPERSTATE */
               + nla_total_size(inet6_ifla6_size()); /* IFLA_PROTINFO */
 }
@@ -5840,6 +5841,14 @@ static int inet6_fill_ifinfo(struct sk_buff *skb, struct 
inet6_dev *idev,
            nla_put_u8(skb, IFLA_OPERSTATE,
                       netif_running(dev) ? dev->operstate : IF_OPER_DOWN))
                goto nla_put_failure;
+
+       rcu_read_lock();
+       if (rtnl_fill_link_netnsid(skb, dev, dev_net(dev), GFP_ATOMIC)) {
+               rcu_read_unlock();
+               goto nla_put_failure;
+       }
+       rcu_read_unlock();
+
        protoinfo = nla_nest_start_noflag(skb, IFLA_PROTINFO);
        if (!protoinfo)
                goto nla_put_failure;
-- 
2.28.0