Commit addecbfb authored Dec 27, 2016 by Johannes Berg Committed by Gerrit - the friendly Code Review server Jan 14, 2017

mac80211: discard multicast and 4-addr A-MSDUs



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.

Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git


Git-commit: ea720935cf6686f72def9d322298bf7e9bd53377
CRs-fixed: 1105600
Change-Id: I9ae3066872858748779999a89c4d983858d4a2d3
Signed-off-by: Rajeev Kumar Sirasanagandla <rsirasan@codeaurora.org>

parent 0236a032

net/mac80211/rx.c

+15 −9

Original line number	Diff line number	Diff line
		@@ -2203,16 +2203,22 @@ ieee80211_rx_h_amsdu(struct ieee80211_rx_data *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)
		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;