Patch "mac80211: discard multicast and 4-addr A-MSDUs" has been added to the 4.4-stable tree

Patch "mac80211: discard multicast and 4-addr A-MSDUs" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    mac80211: discard multicast and 4-addr A-MSDUs

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mac80211-discard-multicast-and-4-addr-a-msdus.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ea720935cf6686f72def9d322298bf7e9bd53377 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Wed, 5 Oct 2016 10:14:42 +0200
Subject: mac80211: discard multicast and 4-addr A-MSDUs

From: Johannes Berg <johannes.berg@intel.com>

commit ea720935cf6686f72def9d322298bf7e9bd53377 upstream.

In mac80211, multicast A-MSDUs are accepted in many cases that
they shouldn't be accepted in:
 * drop A-MSDUs with a multicast A1 (RA), as required by the
   spec in 9.11 (802.11-2012 version)
 * drop A-MSDUs with a 4-addr header, since the fourth address
   can't actually be useful for them; unless 4-address frame
   format is actually requested, even though the fourth address
   is still not useful in this case, but ignored

Accepting the first case, in particular, is very problematic
since it allows anyone else with possession of a GTK to send
unicast frames encapsulated in a multicast A-MSDU, even when
the AP has client isolation enabled.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/mac80211/rx.c |   24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2203,16 +2203,22 @@ ieee80211_rx_h_amsdu(struct ieee80211_rx
 	if (!(status->rx_flags & IEEE80211_RX_AMSDU))
 		return RX_CONTINUE;
 
-	if (ieee80211_has_a4(hdr->frame_control) &&
-	    rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
-	    !rx->sdata->u.vlan.sta)
-		return RX_DROP_UNUSABLE;
+	if (unlikely(ieee80211_has_a4(hdr->frame_control))) {
+		switch (rx->sdata->vif.type) {
+		case NL80211_IFTYPE_AP_VLAN:
+			if (!rx->sdata->u.vlan.sta)
+				return RX_DROP_UNUSABLE;
+			break;
+		case NL80211_IFTYPE_STATION:
+			if (!rx->sdata->u.mgd.use_4addr)
+				return RX_DROP_UNUSABLE;
+			break;
+		default:
+			return RX_DROP_UNUSABLE;
+		}
+	}
 
-	if (is_multicast_ether_addr(hdr->addr1) &&
-	    ((rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
-	      rx->sdata->u.vlan.sta) ||
-	     (rx->sdata->vif.type == NL80211_IFTYPE_STATION &&
-	      rx->sdata->u.mgd.use_4addr)))
+	if (is_multicast_ether_addr(hdr->addr1))
 		return RX_DROP_UNUSABLE;
 
 	skb->dev = dev;


Patches currently in stable-queue which might be from johannes.berg@intel.com are

queue-4.4/mac80211-discard-multicast-and-4-addr-a-msdus.patch