[PATCH 5.12 037/296] mac80211: properly handle A-MSDUs that start with an RFC 1042 header

Greg Kroah-Hartman
2021-05-31T16:00:39Z

From: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>

commit a1d5ff5651ea592c67054233b14b30bf4452999c upstream.

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: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Link: https://lore.kernel.org/r/20210511200110.0b2b886492f0.I23dd5d685fe16d3b0ec8106e8f01b59f499dffed@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/cfg80211.h | 4 ++--
net/mac80211/rx.c | 2 +-
net/wireless/util.c | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)

--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -5756,7 +5756,7 @@ unsigned int ieee80211_get_mesh_hdrlen(s
*/
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
@@ -5768,7 +5768,7 @@ int ieee80211_data_to_8023_exthdr(struct
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);
}

/**
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2681,7 +2681,7 @@ __ieee80211_rx_h_amsdu(struct ieee80211_
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,
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -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
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)))