linux.git/net/wireless/core.c, branch v5.12.5

cfg80211: fix locking in netlink owner interface destruction

2021-05-02T09:10:27+00:00

commit ea6b2098dd02789f68770fd3d5a373732207be2f upstream.

Harald Arnesen reported [1] a deadlock at reboot time, and after
he captured a stack trace a picture developed of what's going on:

The distribution he's using is using iwd (not wpa_supplicant) to
manage wireless. iwd will usually use the "socket owner" option
when it creates new interfaces, so that they're automatically
destroyed when it quits (unexpectedly or otherwise). This is also
done by wpa_supplicant, but it doesn't do it for the normal one,
only for additional ones, which is different with iwd.

Anyway, during shutdown, iwd quits while the netdev is still UP,
i.e. IFF_UP is set. This causes the stack trace that Linus so
nicely transcribed from the pictures:

cfg80211_destroy_iface_wk() takes wiphy_lock
 -> cfg80211_destroy_ifaces()
  ->ieee80211_del_iface
    ->ieeee80211_if_remove
      ->cfg80211_unregister_wdev
        ->unregister_netdevice_queue
          ->dev_close_many
            ->__dev_close_many
              ->raw_notifier_call_chain
                ->cfg80211_netdev_notifier_call
and that last call tries to take wiphy_lock again.

In commit a05829a7222e ("cfg80211: avoid holding the RTNL when
calling the driver") I had taken into account the possibility of
recursing from cfg80211 into cfg80211_netdev_notifier_call() via
the network stack, but only for NETDEV_UNREGISTER, not for what
happens here, NETDEV_GOING_DOWN and NETDEV_DOWN notifications.

Additionally, while this worked still back in commit 78f22b6a3a92
("cfg80211: allow userspace to take ownership of interfaces"), it
missed another corner case: unregistering a netdev will cause
dev_close() to be called, and thus stop wireless operations (e.g.
disconnecting), but there are some types of virtual interfaces in
wifi that don't have a netdev - for that we need an additional
call to cfg80211_leave().

So, to fix this mess, change cfg80211_destroy_ifaces() to not
require the wiphy_lock(), but instead make it acquire it, but
only after it has actually closed all the netdevs on the list,
and then call cfg80211_leave() as well before removing them
from the driver, to fix the second issue. The locking change in
this requires modifying the nl80211 call to not get the wiphy
lock passed in, but acquire it by itself after flushing any
potentially pending destruction requests.

[1] https://lore.kernel.org/r/09464e67-f3de-ac09-28a3-e27b7914ee7d@skogtun.org

Cc: stable@vger.kernel.org # 5.12
Reported-by: Harald Arnesen 
Fixes: 776a39b8196d ("cfg80211: call cfg80211_destroy_ifaces() with wiphy lock held")
Fixes: 78f22b6a3a92 ("cfg80211: allow userspace to take ownership of interfaces")
Signed-off-by: Johannes Berg 
Tested-by: Harald Arnesen 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

cfg80211: fix netdev registration deadlock

2021-02-01T18:30:54+00:00

If register_netdevice() fails after having called cfg80211's
netdev notifier (cfg80211_netdev_notifier_call) it will call
the notifier again with UNREGISTER. This would then lock the
wiphy mutex because we're marked as registered, which causes
a deadlock.

Fix this by separately keeping track of whether or not we're
in the middle of registering to also skip the notifier call
on this unregister.

Reported-by: syzbot+2ae0ca9d7737ad1a62b7@syzkaller.appspotmail.com
Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Link: https://lore.kernel.org/r/20210201192048.ed8bad436737.I7cae042c44b15f80919a285799a15df467e9d42d@changeid
Signed-off-by: Johannes Berg

cfg80211: call cfg80211_destroy_ifaces() with wiphy lock held

2021-01-28T18:11:11+00:00

This is needed since it calls into the driver, which must have the
same context as if we got to destroy an interface through nl80211.
Fix this, and add a direct lockdep assertion so we don't see it
pop up only when the driver calls back to cfg80211.

Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Reported-by: syzbot+4305e814f9b267131776@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20210128183454.d31df9cbd7ce.I1beb07c9492f0ade900e864a098c57041e7a7ebf@changeid
Signed-off-by: Johannes Berg

cfg80211: avoid holding the RTNL when calling the driver

2021-01-26T10:55:50+00:00

Currently, _everything_ in cfg80211 holds the RTNL, and if you
have a slow USB device (or a few) you can get some bad lock
contention on that.

Fix that by re-adding a mutex to each wiphy/rdev as we had at
some point, so we have locking for the wireless_dev lists and
all the other things in there, and also so that drivers still
don't have to worry too much about it (they still won't get
parallel calls for a single device).

Then, we can restrict the RTNL to a few cases where we add or
remove interfaces and really need the added protection. Some
of the global list management still also uses the RTNL, since
we need to have it anyway for netdev management, but we only
hold the RTNL for very short periods of time here.

Link: https://lore.kernel.org/r/20210122161942.81df9f5e047a.I4a8e1a60b18863ea8c5e6d3a0faeafb2d45b2f40@changeid
Tested-by: Marek Szyprowski  [marvell driver issues]
Signed-off-by: Johannes Berg

cfg80211: change netdev registration/unregistration semantics

2021-01-22T15:28:39+00:00

We used to not require anything in terms of registering netdevs
with cfg80211, using a netdev notifier instead. However, in the
next patch reducing RTNL locking, this causes big problems, and
the simplest way is to just require drivers to do things better.

Change the registration/unregistration semantics to require the
drivers to call cfg80211_(un)register_netdevice() when this is
happening due to a cfg80211 request, i.e. add_virtual_intf() or
del_virtual_intf() (or if it somehow has to happen in any other
cfg80211 callback).

Otherwise, in other contexts, drivers may continue to use the
normal netdev (un)registration functions as usual.

Internally, we still use the netdev notifier and track (by the
new wdev->registered bool) if the wdev had already been added
to cfg80211 or not.

Link: https://lore.kernel.org/r/20210122161942.cf2f4b65e4e9.Ida8234e50da13eb675b557bac52a713ad4eddf71@changeid
Signed-off-by: Johannes Berg

Merge tag 'mac80211-next-for-net-next-2020-11-13' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next

2020-11-13T20:03:22+00:00

Johannes Berg says:

====================
Some updates:
 * injection/radiotap updates for new test capabilities
 * remove WDS support - even years ago when we turned
   it off by default it was already basically unusable
 * support for HE (802.11ax) rates for beacons
 * support for some vendor-specific HE rates
 * many other small features/cleanups

* tag 'mac80211-next-for-net-next-2020-11-13' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next: (21 commits)
  nl80211: fix kernel-doc warning in the new SAE attribute
  cfg80211: remove WDS code
  mac80211: remove WDS-related code
  rt2x00: remove WDS code
  b43legacy: remove WDS code
  b43: remove WDS code
  carl9170: remove WDS code
  ath9k: remove WDS code
  wireless: remove CONFIG_WIRELESS_WDS
  mac80211: assure that certain drivers adhere to DONT_REORDER flag
  mac80211: don't overwrite QoS TID of injected frames
  mac80211: adhere to Tx control flag that prevents frame reordering
  mac80211: add radiotap flag to assure frames are not reordered
  mac80211: save HE oper info in BSS config for mesh
  cfg80211: add support to configure HE MCS for beacon rate
  nl80211: fix beacon tx rate mask validation
  nl80211/cfg80211: fix potential infinite loop
  cfg80211: Add support to calculate and report 4096-QAM HE rates
  cfg80211: Add support to configure SAE PWE value to drivers
  ieee80211: Add definition for WFA DPP
  ...
====================

Link: https://lore.kernel.org/r/20201113101148.25268-1-johannes@sipsolutions.net
Signed-off-by: Jakub Kicinski

cfg80211: remove WDS code

2020-11-11T07:39:13+00:00

Remove all the code that was there to configure WDS interfaces,
now that there's no way to reach it anymore.

Link: https://lore.kernel.org/r/20201109105103.8f5b98e4068d.I5f5129041649ef2862b69683574bb3344743727b@changeid
Signed-off-by: Johannes Berg

cfg80211: initialize wdev data earlier

2020-10-30T09:03:59+00:00

There's a race condition in the netdev registration in that
NETDEV_REGISTER actually happens after the netdev is available,
and so if we initialize things only there, we might get called
with an uninitialized wdev through nl80211 - not using a wdev
but using a netdev interface index.

I found this while looking into a syzbot report, but it doesn't
really seem to be related, and unfortunately there's no repro
for it (yet). I can't (yet) explain how it managed to get into
cfg80211_release_pmsr() from nl80211_netlink_notify() without
the wdev having been initialized, as the latter only iterates
the wdevs that are linked into the rdev, which even without the
change here happened after init.

However, looking at this, it seems fairly clear that the init
needs to be done earlier, otherwise we might even re-init on a
netns move, when data might still be pending.

Signed-off-by: Johannes Berg 
Link: https://lore.kernel.org/r/20201009135821.fdcbba3aad65.Ie9201d91dbcb7da32318812effdc1561aeaf4cdc@changeid
Signed-off-by: Johannes Berg

nl80211/cfg80211: support 6 GHz scanning

2020-09-28T11:53:04+00:00

Support 6 GHz scanning, by
 * a new scan flag to scan for colocated BSSes advertised
   by (and found) APs on 2.4 & 5 GHz
 * doing the necessary reduced neighbor report parsing for
   this, to find them
 * adding the ability to split the scan request in case the
   device by itself cannot support this.

Also add some necessary bits in mac80211 to not break with
these changes.

Signed-off-by: Tova Mussai 
Signed-off-by: Johannes Berg 
Link: https://lore.kernel.org/r/20200918113313.232917c93af9.Ida22f0212f9122f47094d81659e879a50434a6a2@changeid
Signed-off-by: Johannes Berg

mm, treewide: rename kzfree() to kfree_sensitive()

2020-08-07T18:33:22+00:00

As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches 
Signed-off-by: Waiman Long 
Signed-off-by: Andrew Morton 
Acked-by: David Howells 
Acked-by: Michal Hocko 
Acked-by: Johannes Weiner 
Cc: Jarkko Sakkinen 
Cc: James Morris 
Cc: "Serge E. Hallyn" 
Cc: Joe Perches 
Cc: Matthew Wilcox 
Cc: David Rientjes 
Cc: Dan Carpenter 
Cc: "Jason A . Donenfeld" 
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds