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70 lines
2.7 KiB
Diff
70 lines
2.7 KiB
Diff
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From: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
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Date: Tue, 11 May 2021 20:02:42 +0200
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Subject: [PATCH] mac80211: assure all fragments are encrypted
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Do not mix plaintext and encrypted fragments in protected Wi-Fi
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networks. This fixes CVE-2020-26147.
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Previously, an attacker was able to first forward a legitimate encrypted
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fragment towards a victim, followed by a plaintext fragment. The
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encrypted and plaintext fragment would then be reassembled. For further
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details see Section 6.3 and Appendix D in the paper "Fragment and Forge:
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Breaking Wi-Fi Through Frame Aggregation and Fragmentation".
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Because of this change there are now two equivalent conditions in the
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code to determine if a received fragment requires sequential PNs, so we
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also move this test to a separate function to make the code easier to
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maintain.
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Cc: stable@vger.kernel.org
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Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
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Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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---
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--- a/net/mac80211/rx.c
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+++ b/net/mac80211/rx.c
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@@ -2204,6 +2204,16 @@ ieee80211_reassemble_find(struct ieee802
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return NULL;
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}
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+static bool requires_sequential_pn(struct ieee80211_rx_data *rx, __le16 fc)
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+{
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+ return rx->key &&
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+ (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
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+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
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+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
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+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
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+ ieee80211_has_protected(fc);
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+}
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+
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static ieee80211_rx_result debug_noinline
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ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
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{
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@@ -2248,12 +2258,7 @@ ieee80211_rx_h_defragment(struct ieee802
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/* This is the first fragment of a new frame. */
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entry = ieee80211_reassemble_add(rx->sdata, frag, seq,
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rx->seqno_idx, &(rx->skb));
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- if (rx->key &&
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- (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
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- rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
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- rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
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- rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
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- ieee80211_has_protected(fc)) {
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+ if (requires_sequential_pn(rx, fc)) {
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int queue = rx->security_idx;
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/* Store CCMP/GCMP PN so that we can verify that the
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@@ -2295,11 +2300,7 @@ ieee80211_rx_h_defragment(struct ieee802
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u8 pn[IEEE80211_CCMP_PN_LEN], *rpn;
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int queue;
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- if (!rx->key ||
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- (rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP &&
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- rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP_256 &&
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- rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP &&
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- rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP_256))
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+ if (!requires_sequential_pn(rx, fc))
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return RX_DROP_UNUSABLE;
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memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
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for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {
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