net-wireless/iwd: add patch for CVE-2020-17497

Bug: https://bugs.gentoo.org/736906

Package-Manager: Portage-3.0.2, Repoman-2.3.23
Signed-off-by: Ben Kohler <bkohler@gentoo.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/net-wireless/iwd/files/iwd-1.8-eapol-prevent-key-reinstallation.patch b/net-wireless/iwd/files/iwd-1.8-eapol-prevent-key-reinstallation.patch
new file mode 100644
index 000000000000..dceb808297e3
--- /dev/null
+++ b/net-wireless/iwd/files/iwd-1.8-eapol-prevent-key-reinstallation.patch
@@ -0,0 +1,73 @@
+From f22ba5aebb569ca54521afd2babdc1f67e3904ea Mon Sep 17 00:00:00 2001
+From: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
+Date: Wed, 12 Aug 2020 15:17:21 +0400
+Subject: eapol: prevent key reinstallation on retransmitted Msg4/4
+
+Currently an adversary can retransmit EAPOL Msg4/4 to make the AP
+reinstall the PTK. Against older Linux kernels this can subsequently
+be used to decrypt, replay, and possibly decrypt frames. See the
+KRACK attacks research at krackattacks.com for attack scenarios.
+In this case no machine-in-the-middle position is needed to trigger
+the key reinstallation.
+
+Fix this by using the ptk_complete boolean to track when the 4-way
+handshake has completed (similar to its usage for clients). When
+receiving a retransmitted Msg4/4 accept this frame but do not reinstall
+the PTK.
+
+Credits to Chris M. Stone, Sam Thomas, and Tom Chothia of Birmingham
+University to help discover this issue.
+---
+ src/eapol.c | 15 ++++++++++++---
+ 1 file changed, 12 insertions(+), 3 deletions(-)
+
+diff --git a/src/eapol.c b/src/eapol.c
+index b0036c10..e3581cfe 100644
+--- a/src/eapol.c
++++ b/src/eapol.c
+@@ -1462,7 +1462,6 @@ static void eapol_handle_ptk_2_of_4(struct eapol_sm *sm,
+ 	memcpy(sm->handshake->snonce, ek->key_nonce,
+ 			sizeof(sm->handshake->snonce));
+ 	sm->handshake->have_snonce = true;
+-	sm->handshake->ptk_complete = true;
+ 
+ 	sm->frame_retry = 0;
+ 
+@@ -1782,7 +1781,15 @@ static void eapol_handle_ptk_4_of_4(struct eapol_sm *sm,
+ 	l_timeout_remove(sm->timeout);
+ 	sm->timeout = NULL;
+ 
+-	handshake_state_install_ptk(sm->handshake);
++	/*
++	 * If ptk_complete is set, then we are receiving Message 4 again.
++	 * This might be a retransmission, so accept but don't install
++	 * the keys again.
++	 */
++	if (!sm->handshake->ptk_complete)
++		handshake_state_install_ptk(sm->handshake);
++
++	sm->handshake->ptk_complete = true;
+ }
+ 
+ static void eapol_handle_gtk_1_of_2(struct eapol_sm *sm,
+@@ -2185,6 +2192,7 @@ static void eapol_auth_key_handle(struct eapol_sm *sm,
+ 	size_t frame_len = 4 + L_BE16_TO_CPU(frame->header.packet_len);
+ 	const struct eapol_key *ek = eapol_key_validate((const void *) frame,
+ 							frame_len, sm->mic_len);
++	uint16_t key_data_len;
+ 
+ 	if (!ek)
+ 		return;
+@@ -2199,7 +2207,8 @@ static void eapol_auth_key_handle(struct eapol_sm *sm,
+ 	if (!sm->handshake->have_anonce)
+ 		return; /* Not expecting an EAPoL-Key yet */
+ 
+-	if (!sm->handshake->ptk_complete)
++	key_data_len = EAPOL_KEY_DATA_LEN(ek, sm->mic_len);
++	if (key_data_len != 0)
+ 		eapol_handle_ptk_2_of_4(sm, ek);
+ 	else
+ 		eapol_handle_ptk_4_of_4(sm, ek);
+-- 
+cgit 1.2.3-1.el7
+