From: Sven Eckelmann <sven@narfation.org>
To: b.a.t.m.a.n@lists.open-mesh.org
Cc: Sven Eckelmann <sven@narfation.org>,
Sabrina Dubroca <sd@queasysnail.net>
Subject: [RFC PATCH 3/4] batman-adv: Don't expect inter-netns unique iflink indices
Date: Mon, 28 Feb 2022 00:52:56 +0100 [thread overview]
Message-ID: <20220227235257.1324636-3-sven@narfation.org> (raw)
In-Reply-To: <20220227235257.1324636-1-sven@narfation.org>
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, an "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.
Fixes: 3d48811b27f5 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface")
Fixes: 2b45bb6c3aad ("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>
---
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 8ed128bb..cdb6e542 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -157,13 +157,15 @@ 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.. */
@@ -223,8 +225,7 @@ 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;
}
@@ -235,6 +236,14 @@ 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:
--
2.30.2
next prev parent reply other threads:[~2022-02-27 23:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-27 23:52 [RFC PATCH 1/4] batman-adv: Request iflink once in batadv-on-batadv check Sven Eckelmann
2022-02-27 23:52 ` [RFC PATCH 2/4] batman-adv: Request iflink once in batadv_get_real_netdevice Sven Eckelmann
2022-02-27 23:52 ` Sven Eckelmann [this message]
2022-02-27 23:52 ` [RFC PATCH 4/4] batman-adv: Demote batadv-on-batadv skip error message Sven Eckelmann
[not found] ` <CAHhjh1P1WvsEP3zo7KGPmexiHCiZrOUrxA_7RR17_wZapUupqQ@mail.gmail.com>
2022-02-28 0:30 ` Sven Eckelmann
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