| From 6c1f41afc1dbe59d9d3c8bb0d80b749c119aa334 Mon Sep 17 00:00:00 2001 |
| From: Sven Eckelmann <sven@narfation.org> |
| Date: Sun, 27 Feb 2022 23:23:49 +0100 |
| Subject: batman-adv: Don't expect inter-netns unique iflink indices |
| |
| From: Sven Eckelmann <sven@narfation.org> |
| |
| commit 6c1f41afc1dbe59d9d3c8bb0d80b749c119aa334 upstream. |
| |
| The ifindex doesn't have to be unique for multiple network namespaces on |
| the same machine. |
| |
| $ ip netns add test1 |
| $ ip -net test1 link add dummy1 type dummy |
| $ ip netns add test2 |
| $ ip -net test2 link add dummy2 type dummy |
| |
| $ ip -net test1 link show dev dummy1 |
| 6: dummy1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 |
| link/ether 96:81:55:1e:dd:85 brd ff:ff:ff:ff:ff:ff |
| $ ip -net test2 link show dev dummy2 |
| 6: dummy2: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 |
| link/ether 5a:3c:af:35:07:c3 brd ff:ff:ff:ff:ff:ff |
| |
| But the batman-adv code to walk through the various layers of virtual |
| interfaces uses this assumption because dev_get_iflink handles it |
| internally and doesn't return the actual netns of the iflink. And |
| dev_get_iflink only documents the situation where ifindex == iflink for |
| physical devices. |
| |
| But only checking for dev->netdev_ops->ndo_get_iflink is also not an option |
| because ipoib_get_iflink implements it even when it sometimes returns an |
| iflink != ifindex and sometimes iflink == ifindex. The caller must |
| therefore make sure itself to check both netns and iflink + ifindex for |
| equality. Only when they are equal, a "physical" interface was detected |
| which should stop the traversal. On the other hand, vxcan_get_iflink can |
| also return 0 in case there was currently no valid peer. In this case, it |
| is still necessary to stop. |
| |
| Fixes: b7eddd0b3950 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface") |
| Fixes: 5ed4a460a1d3 ("batman-adv: additional checks for virtual interfaces on top of WiFi") |
| Reported-by: Sabrina Dubroca <sd@queasysnail.net> |
| Signed-off-by: Sven Eckelmann <sven@narfation.org> |
| Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/batman-adv/hard-interface.c | 19 ++++++++++++++----- |
| 1 file changed, 14 insertions(+), 5 deletions(-) |
| |
| --- a/net/batman-adv/hard-interface.c |
| +++ b/net/batman-adv/hard-interface.c |
| @@ -159,13 +159,15 @@ static bool batadv_is_on_batman_iface(co |
| return true; |
| |
| iflink = dev_get_iflink(net_dev); |
| - |
| - /* no more parents..stop recursion */ |
| - if (iflink == 0 || iflink == net_dev->ifindex) |
| + if (iflink == 0) |
| return false; |
| |
| parent_net = batadv_getlink_net(net_dev, net); |
| |
| + /* iflink to itself, most likely physical device */ |
| + if (net == parent_net && iflink == net_dev->ifindex) |
| + return false; |
| + |
| /* recurse over the parent device */ |
| parent_dev = __dev_get_by_index((struct net *)parent_net, iflink); |
| /* if we got a NULL parent_dev there is something broken.. */ |
| @@ -225,8 +227,7 @@ static struct net_device *batadv_get_rea |
| return NULL; |
| |
| iflink = dev_get_iflink(netdev); |
| - |
| - if (netdev->ifindex == iflink) { |
| + if (iflink == 0) { |
| dev_hold(netdev); |
| return netdev; |
| } |
| @@ -237,6 +238,14 @@ static struct net_device *batadv_get_rea |
| |
| net = dev_net(hard_iface->soft_iface); |
| real_net = batadv_getlink_net(netdev, net); |
| + |
| + /* iflink to itself, most likely physical device */ |
| + if (net == real_net && netdev->ifindex == iflink) { |
| + real_netdev = netdev; |
| + dev_hold(real_netdev); |
| + goto out; |
| + } |
| + |
| real_netdev = dev_get_by_index(real_net, iflink); |
| |
| out: |