From a1d5ff5651ea592c67054233b14b30bf4452999c Mon Sep 17 00:00:00 2001
From: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Date: Tue, 11 May 2021 20:02:44 +0200
Subject: [PATCH] mac80211: properly handle A-MSDUs that start with an RFC 1042 header
Git-commit: a1d5ff5651ea592c67054233b14b30bf4452999c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git
Patch-mainline: Queued in subsystem maintainer repo
References: CVE-2020-24587 CVE-2020-24586 bsc#1185863 bsc#1185862 bsc#1185859
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
include/net/cfg80211.h | 5 +++--
net/mac80211/rx.c | 2 +-
net/wireless/util.c | 5 +++--
3 files changed, 7 insertions(+), 5 deletions(-)
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -4295,7 +4295,8 @@ unsigned int ieee80211_get_mesh_hdrlen(s
* Return: 0 on success. Non-zero on error.
*/
int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
- const u8 *addr, enum nl80211_iftype iftype);
+ const u8 *addr, enum nl80211_iftype iftype,
+ bool is_amsdu);
/**
* ieee80211_data_to_8023 - convert an 802.11 data frame to 802.3
@@ -4307,7 +4308,7 @@ 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);
+ return ieee80211_data_to_8023_exthdr(skb, NULL, addr, iftype, false);
}
/**
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2429,7 +2429,7 @@ ieee80211_rx_h_amsdu(struct ieee80211_rx
if (ieee80211_data_to_8023_exthdr(skb, ðhdr,
rx->sdata->vif.addr,
- rx->sdata->vif.type))
+ rx->sdata->vif.type, 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
@@ -421,7 +421,8 @@ unsigned int ieee80211_get_mesh_hdrlen(s
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)
+ const u8 *addr, enum nl80211_iftype iftype,
+ bool is_amsdu)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct {
@@ -509,7 +510,7 @@ 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)))