ipv6: Convert inet6_ioctl() to per-netns RTNL.

These functions are called from inet6_ioctl() with a socket's netns
and hold RTNL.

  * SIOCSIFADDR    : addrconf_add_ifaddr()
  * SIOCDIFADDR    : addrconf_del_ifaddr()
  * SIOCSIFDSTADDR : addrconf_set_dstaddr()

Let's use rtnl_net_lock().

Signed-off-by: Kuniyuki Iwashima <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: q2ven

net/ipv6/addrconf.c

@@ -2979,11 +2979,11 @@ int addrconf_set_dstaddr(struct net *net, void __user *arg)
 	if (copy_from_user(&ireq, arg, sizeof(struct in6_ifreq)))
 		return -EFAULT;
 
-	rtnl_lock();
+	rtnl_net_lock(net);
 	dev = __dev_get_by_index(net, ireq.ifr6_ifindex);
 	if (dev && dev->type == ARPHRD_SIT)
 		err = addrconf_set_sit_dstaddr(net, dev, &ireq);
-	rtnl_unlock();
+	rtnl_net_unlock(net);
 	return err;
 }
 
@@ -3181,9 +3181,9 @@ int addrconf_add_ifaddr(struct net *net, void __user *arg)
 	cfg.pfx = &ireq.ifr6_addr;
 	cfg.plen = ireq.ifr6_prefixlen;
 
-	rtnl_lock();
+	rtnl_net_lock(net);
 	err = inet6_addr_add(net, ireq.ifr6_ifindex, &cfg, NULL);
-	rtnl_unlock();
+	rtnl_net_unlock(net);
 	return err;
 }
 
@@ -3198,10 +3198,10 @@ int addrconf_del_ifaddr(struct net *net, void __user *arg)
 	if (copy_from_user(&ireq, arg, sizeof(struct in6_ifreq)))
 		return -EFAULT;
 
-	rtnl_lock();
+	rtnl_net_lock(net);
 	err = inet6_addr_del(net, ireq.ifr6_ifindex, 0, &ireq.ifr6_addr,
 			     ireq.ifr6_prefixlen, NULL);
-	rtnl_unlock();
+	rtnl_net_unlock(net);
 	return err;
 }