From 3f020a3c6b4dd268cf984f962d420171e2b84264 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 28 May 2022 16:06:17 +0800 Subject: [PATCH] batman-adv: Don't expect inter-netns unique iflink indices stable inclusion from stable-v5.10.104 commit a9c4a74ad5ae4a23ce4db8cc9a0ead08ce5b60f3 bugzilla: https://gitee.com/openeuler/kernel/issues/I56XAC Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a9c4a74ad5ae4a23ce4db8cc9a0ead08ce5b60f3 -------------------------------- 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: 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: 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 Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yu Liao Reviewed-by: Wei Li Signed-off-by: Zheng Zengkai --- net/batman-adv/hard-interface.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index a82ab29aef33..fe0898a9b4e8 100644 --- 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(const struct net_device *net_dev) 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_real_netdevice(struct net_device *netdev) 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_real_netdevice(struct net_device *netdev) 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: -- GitLab