mac80211: assure all fragments are encrypted
Do not mix plaintext and encrypted fragments in protected Wi-Fi networks. This fixes CVE-2020-26147. Previously, an attacker was able to first forward a legitimate encrypted fragment towards a victim, followed by a plaintext fragment. The encrypted and plaintext fragment would then be reassembled. For further details see Section 6.3 and Appendix D in the paper "Fragment and Forge: Breaking Wi-Fi Through Frame Aggregation and Fragmentation". Because of this change there are now two equivalent conditions in the code to determine if a received fragment requires sequential PNs, so we also move this test to a separate function to make the code easier to maintain. Cc: stable@vger.kernel.org Signed-off-by:Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be> Link: https://lore.kernel.org/r/20210511200110.30c4394bb835.I5acfdb552cc1d20c339c262315950b3eac491397@changeid Signed-off-by:
Johannes Berg <johannes.berg@intel.com>
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297c4de6
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