* [PATCH maint 1/3] batman-adv: Request iflink once in batadv-on-batadv check
@ 2022-03-02 18:49 Sven Eckelmann
2022-03-02 18:49 ` [PATCH maint 2/3] batman-adv: Request iflink once in batadv_get_real_netdevice Sven Eckelmann
2022-03-02 18:49 ` [PATCH maint 3/3] batman-adv: Don't expect inter-netns unique iflink indices Sven Eckelmann
0 siblings, 2 replies; 3+ messages in thread
From: Sven Eckelmann @ 2022-03-02 18:49 UTC (permalink / raw)
To: b.a.t.m.a.n; +Cc: Sven Eckelmann
There is no need to call dev_get_iflink multiple times for the same
net_device in batadv_is_on_batman_iface. And since some of the
.ndo_get_iflink callbacks are dynamic (for example via RCUs like in
vxcan_get_iflink), it could easily happen that the returned values are not
stable. The pre-checks before __dev_get_by_index are then of course bogus.
Fixes: 3d48811b27f5 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
net/batman-adv/hard-interface.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 59d19097..774a26c5 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -149,22 +149,23 @@ static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
struct net *net = dev_net(net_dev);
struct net_device *parent_dev;
struct net *parent_net;
+ int iflink;
bool ret;
/* check if this is a batman-adv mesh interface */
if (batadv_softif_is_valid(net_dev))
return true;
+ iflink = dev_get_iflink(net_dev);
+
/* no more parents..stop recursion */
- if (dev_get_iflink(net_dev) == 0 ||
- dev_get_iflink(net_dev) == net_dev->ifindex)
+ if (iflink == 0 || iflink == net_dev->ifindex)
return false;
parent_net = batadv_getlink_net(net_dev, net);
/* recurse over the parent device */
- parent_dev = __dev_get_by_index((struct net *)parent_net,
- dev_get_iflink(net_dev));
+ parent_dev = __dev_get_by_index((struct net *)parent_net, iflink);
/* if we got a NULL parent_dev there is something broken.. */
if (!parent_dev) {
pr_err("Cannot find parent device\n");
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH maint 2/3] batman-adv: Request iflink once in batadv_get_real_netdevice
2022-03-02 18:49 [PATCH maint 1/3] batman-adv: Request iflink once in batadv-on-batadv check Sven Eckelmann
@ 2022-03-02 18:49 ` Sven Eckelmann
2022-03-02 18:49 ` [PATCH maint 3/3] batman-adv: Don't expect inter-netns unique iflink indices Sven Eckelmann
1 sibling, 0 replies; 3+ messages in thread
From: Sven Eckelmann @ 2022-03-02 18:49 UTC (permalink / raw)
To: b.a.t.m.a.n; +Cc: Sven Eckelmann
There is no need to call dev_get_iflink multiple times for the same
net_device in batadv_get_real_netdevice. And since some of the
ndo_get_iflink callbacks are dynamic (for example via RCUs like in
vxcan_get_iflink), it could easily happen that the returned values are not
stable. The pre-checks before __dev_get_by_index are then of course bogus.
Fixes: 2b45bb6c3aad ("batman-adv: additional checks for virtual interfaces on top of WiFi")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
net/batman-adv/hard-interface.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 774a26c5..8ed128bb 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -215,14 +215,16 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
struct net_device *real_netdev = NULL;
struct net *real_net;
struct net *net;
- int ifindex;
+ int iflink;
ASSERT_RTNL();
if (!netdev)
return NULL;
- if (netdev->ifindex == dev_get_iflink(netdev)) {
+ iflink = dev_get_iflink(netdev);
+
+ if (netdev->ifindex == iflink) {
dev_hold(netdev);
return netdev;
}
@@ -232,9 +234,8 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
goto out;
net = dev_net(hard_iface->soft_iface);
- ifindex = dev_get_iflink(netdev);
real_net = batadv_getlink_net(netdev, net);
- real_netdev = dev_get_by_index(real_net, ifindex);
+ real_netdev = dev_get_by_index(real_net, iflink);
out:
batadv_hardif_put(hard_iface);
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH maint 3/3] batman-adv: Don't expect inter-netns unique iflink indices
2022-03-02 18:49 [PATCH maint 1/3] batman-adv: Request iflink once in batadv-on-batadv check Sven Eckelmann
2022-03-02 18:49 ` [PATCH maint 2/3] batman-adv: Request iflink once in batadv_get_real_netdevice Sven Eckelmann
@ 2022-03-02 18:49 ` Sven Eckelmann
1 sibling, 0 replies; 3+ messages in thread
From: Sven Eckelmann @ 2022-03-02 18:49 UTC (permalink / raw)
To: b.a.t.m.a.n; +Cc: Sven Eckelmann, Sabrina Dubroca
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: 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
^ permalink raw reply related [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-03-02 18:49 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-03-02 18:49 [PATCH maint 1/3] batman-adv: Request iflink once in batadv-on-batadv check Sven Eckelmann
2022-03-02 18:49 ` [PATCH maint 2/3] batman-adv: Request iflink once in batadv_get_real_netdevice Sven Eckelmann
2022-03-02 18:49 ` [PATCH maint 3/3] batman-adv: Don't expect inter-netns unique iflink indices Sven Eckelmann
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