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FragAttacks: Fragmentation & Aggregation Attacks
144314eaa7
Linux kernel v4.17 added the ability to request sending control port frames via nl80211 instead of a normal network socket. Doing this provides the device driver with ordering information between the control port frames and the installation of keys. This empowers it to avoid race conditions between, for example, PTK replacement and the sending of frame 4 of the 4-way rekeying handshake in an RSNA. The key difference between a TX_CONTROL_PORT and normal socket send is that the device driver will certainly get any EAPOL frames comprising a 4-way handshake before it gets the key installation call for the derived key. By flushing its TX buffers it can then ensure that no pending EAPOL frames are inadvertently encrypted with a key that the peer will not yet have installed. Update the RSN supplicant system to use this new operation for sending EAPOL-Key frames when the driver reports that this capability is available; otherwise, fall back to a normal Ethernet TX. I have tested this on DMG (11ad/ay) devices with an out-of-tree Linux driver that does not use mac80211. Without this patch I consistently see PTK rekeying fail if message 4/4 shares a stream with other in-flight traffic. With this patch, and the driver updated to flush the relevant TX queue before overwriting a PTK (knowing, now, that if there was a message 4/4 related to the key installation, it has already entered the driver queue), rekeying is reliable. There is still data loss surrounding key installation - this problem is alluded to in IEEE Std 802.11-2016, 12.6.21, where extended Key ID support is described as the eventual solution. This patch aims to at least prevent rekeying from totally breaking the association, in a way that works on kernels as far back as 4.17 (as per Alexander Wetzel extended Key ID support should be possible on 5.2). See http://lists.infradead.org/pipermail/hostap/2019-May/040089.html for a little more context. Signed-off-by: Brendan Jackman <brendan.jackman@bluwireless.co.uk> |
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| doc | ||
| eap_example | ||
| hostapd | ||
| hs20 | ||
| radius_example | ||
| src | ||
| tests | ||
| wlantest | ||
| wpa_supplicant | ||
| wpadebug | ||
| wpaspy | ||
| .gitignore | ||
| Android.mk | ||
| build_release | ||
| CONTRIBUTIONS | ||
| COPYING | ||
| README | ||
wpa_supplicant and hostapd -------------------------- Copyright (c) 2002-2019, Jouni Malinen <j@w1.fi> and contributors All Rights Reserved. These programs are licensed under the BSD license (the one with advertisement clause removed). If you are submitting changes to the project, please see CONTRIBUTIONS file for more instructions. This package may include either wpa_supplicant, hostapd, or both. See README file respective subdirectories (wpa_supplicant/README or hostapd/README) for more details. Source code files were moved around in v0.6.x releases and compared to earlier releases, the programs are now built by first going to a subdirectory (wpa_supplicant or hostapd) and creating build configuration (.config) and running 'make' there (for Linux/BSD/cygwin builds). License ------- This software may be distributed, used, and modified under the terms of BSD license: Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name(s) of the above-listed copyright holder(s) nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.