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From: Johannes Berg <johannes@sipsolutions.net>
To: linux-wireless@vger.kernel.org
Cc: Wen Gong <wgong@codeaurora.org>, stable@vger.kernel.org
Subject: [PATCH 10/18] mac80211: extend protection against mixed key and fragment cache attacks
Date: Tue, 11 May 2021 20:02:51 +0200
Message-ID: <20210511200110.037aa5ca0390.I7bb888e2965a0db02a67075fcb5deb50eb7408aa@changeid> (raw)
In-Reply-To: <20210511180259.159598-1-johannes@sipsolutions.net>

From: Wen Gong <wgong@codeaurora.org>

For some chips/drivers, e.g., QCA6174 with ath10k, the decryption is
done by the hardware, and the Protected bit in the Frame Control field
is cleared in the lower level driver before the frame is passed to
mac80211. In such cases, the condition for ieee80211_has_protected() is
not met in ieee80211_rx_h_defragment() of mac80211 and the new security
validation steps are not executed.

Extend mac80211 to cover the case where the Protected bit has been
cleared, but the frame is indicated as having been decrypted by the
hardware. This extends protection against mixed key and fragment cache
attack for additional drivers/chips. This fixes CVE-2020-24586 and
CVE-2020-24587 for such cases.

Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1

Cc: stable@vger.kernel.org
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/mac80211/rx.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 22a925899a9e..1bb43edd47b6 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2229,6 +2229,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 	unsigned int frag, seq;
 	struct ieee80211_fragment_entry *entry;
 	struct sk_buff *skb;
+	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
 
 	hdr = (struct ieee80211_hdr *)rx->skb->data;
 	fc = hdr->frame_control;
@@ -2287,7 +2288,9 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 				     sizeof(rx->key->u.gcmp.rx_pn[queue]));
 			BUILD_BUG_ON(IEEE80211_CCMP_PN_LEN !=
 				     IEEE80211_GCMP_PN_LEN);
-		} else if (rx->key && ieee80211_has_protected(fc)) {
+		} else if (rx->key &&
+			   (ieee80211_has_protected(fc) ||
+			    (status->flag & RX_FLAG_DECRYPTED))) {
 			entry->is_protected = true;
 			entry->key_color = rx->key->color;
 		}
@@ -2332,13 +2335,19 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 			return RX_DROP_UNUSABLE;
 		memcpy(entry->last_pn, pn, IEEE80211_CCMP_PN_LEN);
 	} else if (entry->is_protected &&
-		   (!rx->key || !ieee80211_has_protected(fc) ||
+		   (!rx->key ||
+		    (!ieee80211_has_protected(fc) &&
+		     !(status->flag & RX_FLAG_DECRYPTED)) ||
 		    rx->key->color != entry->key_color)) {
 		/* Drop this as a mixed key or fragment cache attack, even
 		 * if for TKIP Michael MIC should protect us, and WEP is a
 		 * lost cause anyway.
 		 */
 		return RX_DROP_UNUSABLE;
+	} else if (entry->is_protected && rx->key &&
+		   entry->key_color != rx->key->color &&
+		   (status->flag & RX_FLAG_DECRYPTED)) {
+		return RX_DROP_UNUSABLE;
 	}
 
 	skb_pull(rx->skb, ieee80211_hdrlen(fc));
-- 
2.30.2


  parent reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11 18:02 [PATCH 00/18] mac80211/driver security fixes Johannes Berg
2021-05-11 18:02 ` [PATCH 01/18] mac80211: assure all fragments are encrypted Johannes Berg
2021-05-11 18:02 ` [PATCH 02/18] mac80211: prevent mixed key and fragment cache attacks Johannes Berg
2021-05-11 18:02 ` [PATCH 03/18] mac80211: properly handle A-MSDUs that start with an RFC 1042 header Johannes Berg
2021-05-11 18:02 ` [PATCH 04/18] cfg80211: mitigate A-MSDU aggregation attacks Johannes Berg
2021-05-11 18:02 ` [PATCH 05/18] mac80211: drop A-MSDUs on old ciphers Johannes Berg
2021-05-11 18:02 ` [PATCH 06/18] mac80211: add fragment cache to sta_info Johannes Berg
2021-05-11 18:02 ` [PATCH 07/18] mac80211: check defrag PN against current frame Johannes Berg
2021-05-11 18:02 ` [PATCH 08/18] mac80211: prevent attacks on TKIP/WEP as well Johannes Berg
2021-05-11 18:02 ` [PATCH 09/18] mac80211: do not accept/forward invalid EAPOL frames Johannes Berg
2021-05-11 18:02 ` Johannes Berg [this message]
2021-05-11 18:02 ` [PATCH 11/18] ath10k: add CCMP PN replay protection for fragmented frames for PCIe Johannes Berg
2021-05-14 22:23   ` Abhishek Kumar
2021-05-11 18:02 ` [PATCH 12/18] ath10k: drop fragments with multicast DA " Johannes Berg
2021-05-11 18:02 ` [PATCH 13/18] ath10k: drop fragments with multicast DA for SDIO Johannes Berg
2021-05-11 18:02 ` [PATCH 14/18] ath10k: drop MPDU which has discard flag set by firmware " Johannes Berg
2021-05-12 18:35   ` Brian Norris
2021-05-13 17:18     ` Jeff Johnson
2021-05-11 18:02 ` [PATCH 15/18] ath10k: Fix TKIP Michael MIC verification for PCIe Johannes Berg
2021-05-11 18:02 ` [PATCH 16/18] ath10k: Validate first subframe of A-MSDU before processing the list Johannes Berg
2021-05-11 18:02 ` [PATCH 17/18] ath11k: Clear the fragment cache during key install Johannes Berg
2021-05-11 18:02 ` [PATCH 18/18] ath11k: Drop multicast fragments Johannes Berg
2021-05-17 18:54 ` [PATCH 00/18] mac80211/driver security fixes Ben Greear

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