Commit a1d5ff56 authored by Mathy Vanhoef's avatar Mathy Vanhoef Committed by Johannes Berg
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mac80211: properly handle A-MSDUs that start with an RFC 1042 header 



Properly parse A-MSDUs whose first 6 bytes happen to equal a rfc1042
header. This can occur in practice when the destination MAC address
equals AA:AA:03:00:00:00. More importantly, this simplifies the next
patch to mitigate A-MSDU injection attacks.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Link: https://lore.kernel.org/r/20210511200110.0b2b886492f0.I23dd5d685fe16d3b0ec8106e8f01b59f499dffed@changeid


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 94034c40

include/net/cfg80211.h

+2 −2
Original line number Diff line number Diff line
@@ -5760,7 +5760,7 @@ unsigned int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr); 
 */

int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,

				  const u8 *addr, enum nl80211_iftype iftype,

				  u8 data_offset);

				  u8 data_offset, bool is_amsdu);



/**

 * ieee80211_data_to_8023 - convert an 802.11 data frame to 802.3
@@ -5772,7 +5772,7 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr, 
static inline int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,

					 enum nl80211_iftype iftype)

{

	return ieee80211_data_to_8023_exthdr(skb, NULL, addr, iftype, 0);

	return ieee80211_data_to_8023_exthdr(skb, NULL, addr, iftype, 0, false);

}



/**

net/mac80211/rx.c

+1 −1
Original line number Diff line number Diff line
@@ -2682,7 +2682,7 @@ __ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx, u8 data_offset) 
	if (ieee80211_data_to_8023_exthdr(skb, &ethhdr,

					  rx->sdata->vif.addr,

					  rx->sdata->vif.type,

					  data_offset))

					  data_offset, true))

		return RX_DROP_UNUSABLE;



	ieee80211_amsdu_to_8023s(skb, &frame_list, dev->dev_addr,

net/wireless/util.c

+2 −2
Original line number Diff line number Diff line
@@ -542,7 +542,7 @@ EXPORT_SYMBOL(ieee80211_get_mesh_hdrlen); 


int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,

				  const u8 *addr, enum nl80211_iftype iftype,

				  u8 data_offset)

				  u8 data_offset, bool is_amsdu)

{

	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

	struct {
@@ -629,7 +629,7 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr, 
	skb_copy_bits(skb, hdrlen, &payload, sizeof(payload));

	tmp.h_proto = payload.proto;



	if (likely((ether_addr_equal(payload.hdr, rfc1042_header) &&

	if (likely((!is_amsdu && ether_addr_equal(payload.hdr, rfc1042_header) &&

		    tmp.h_proto != htons(ETH_P_AARP) &&

		    tmp.h_proto != htons(ETH_P_IPX)) ||

		   ether_addr_equal(payload.hdr, bridge_tunnel_header)))