From 8f3c724202578644145506486dc1cede108c0a2c Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Sat, 12 Sep 2026 23:00:33 +0000 Subject: [PATCH] ip_tunnel: Support per-netns device unregistration. ip_tunnel_delete_net() iterates ip_tunnel devices whose link_net is dying and queues them for destruction. The devices may reside in different netns. Let's use unregister_netdevice_queue_net() to support per-netns device unregistration. Even after ip_tunnel_delete_net() queues a cross-netns ip_tunnel device, ip_tunnel_changelink(), ip_tunnel_dellink(), and ip_tunnel_ctl() could be called concurrently for it (once RTNL is removed). In such a case, __rtnl_net_unlock() will perform the unregistration. Also, ip_tunnel_ctl() needs to check check_net(t->net), otherwise it could create a new dev in dying netns after ip_tunnel_delete_net(). In the example below, we can see the fallback tunnel device (gre0) and the cross-netns device (gre1) are unregistered by different processes: # bpftrace -e '#include kprobe:ip_tunnel_uninit { $dev = (struct net_device *)arg0; printf("PID: %d | DEV: %s%s\n", pid, $dev->name, kstack()); } kprobe:ipgre_exit_rtnl { printf("PID: %d%s\n", pid, kstack()); }' & # ip netns add ns1 # ip netns add ns2 # ip -n ns1 link add name gre1 link-netns ns2 \ type gre local 192.168.0.1 remote 192.168.1.1 # ip netns del ns2 PID: 12 ipgre_exit_rtnl+5 ops_undo_list+702 cleanup_net+1122 process_scheduled_works+2538 ... PID: 12 | DEV: gre0 <------ fallback device (itn->fb_tunnel_dev). ip_tunnel_uninit+5 unregister_netdevice_many_notify+7129 unregister_netdevice_many_net+1050 __rtnl_net_unlock+37 ops_undo_list+754 cleanup_net+1122 process_scheduled_works+2538 ... PID: 10 | DEV: gre1 ip_tunnel_uninit+5 unregister_netdevice_many_notify+7129 unregister_netdevice_many_net+1050 rtnl_net_work_func+136 process_scheduled_works+2538 Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260912230043.2586313-8-kuniyu@google.com Reviewed-by: Ido Schimmel Signed-off-by: Paolo Abeni --- net/ipv4/ip_tunnel.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index d44976395c7c..0875474a578a 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -205,6 +205,11 @@ static void ip_tunnel_del(struct ip_tunnel_net *itn, struct ip_tunnel *t) hlist_del_init_rcu(&t->hash_node); } +static bool ip_tunnel_unregistering(struct ip_tunnel *t) +{ + return hlist_unhashed(&t->hash_node); +} + static struct ip_tunnel *ip_tunnel_find(struct ip_tunnel_net *itn, struct ip_tunnel_parm_kern *parms, int type) @@ -893,20 +898,22 @@ static void ip_tunnel_update(struct ip_tunnel_net *itn, netdev_state_change(dev); } -static void __ip_tunnel_dellink(struct net_device *dev, struct list_head *head) +static void __ip_tunnel_dellink(struct net *net, struct net_device *dev, + struct list_head *head) { struct ip_tunnel *tunnel = netdev_priv(dev); struct ip_tunnel_net *itn; itn = net_generic(tunnel->net, tunnel->ip_tnl_net_id); ip_tunnel_del(itn, tunnel); - unregister_netdevice_queue(dev, head); + unregister_netdevice_queue_net(net, dev, head); } int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, int cmd) { struct ip_tunnel *t = netdev_priv(dev); + struct net *orig_net = dev_net(dev); struct ip_tunnel_net *itn; LIST_HEAD(dev_kill_list); struct net *net = t->net; @@ -918,6 +925,11 @@ int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, mutex_lock(&itn->tunnels_lock); + if (!check_net(net)) { + err = -EBUSY; + goto done; + } + switch (cmd) { case SIOCGETTUNNEL: if (dev == itn->fb_tunnel_dev) { @@ -977,7 +989,7 @@ int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, } } - if (t) { + if (t && !ip_tunnel_unregistering(t)) { err = 0; ip_tunnel_update(itn, t, dev, p, true, 0); } else { @@ -1001,7 +1013,9 @@ int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, dev = t->dev; } - __ip_tunnel_dellink(dev, &dev_kill_list); + if (!ip_tunnel_unregistering(t)) + __ip_tunnel_dellink(orig_net, dev, &dev_kill_list); + err = 0; break; @@ -1109,7 +1123,8 @@ void ip_tunnel_dellink(struct net_device *dev, struct list_head *head) if (itn->fb_tunnel_dev != dev) { mutex_lock(&itn->tunnels_lock); - __ip_tunnel_dellink(dev, head); + if (!ip_tunnel_unregistering(tunnel)) + __ip_tunnel_dellink(dev_net(dev), dev, head); mutex_unlock(&itn->tunnels_lock); } } @@ -1192,7 +1207,7 @@ void ip_tunnel_delete_net(struct net *net, unsigned int id, struct ip_tunnel *t; hlist_for_each_entry_safe(t, n, thead, hash_node) - __ip_tunnel_dellink(t->dev, head); + __ip_tunnel_dellink(net, t->dev, head); } mutex_unlock(&itn->tunnels_lock); @@ -1302,6 +1317,11 @@ int ip_tunnel_changelink(struct net_device *dev, struct nlattr *tb[], } } + if (ip_tunnel_unregistering(t)) { + err = -ENODEV; + goto out; + } + ip_tunnel_update(itn, t, dev, p, !tb[IFLA_MTU], fwmark); out: mutex_unlock(&itn->tunnels_lock);