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From 8f82bc94e8697a9d47fa8774dfdaaede1084912c Mon Sep 17 00:00:00 2001
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From: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
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Date: Fri, 29 Sep 2017 04:22:51 +0200
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Subject: [PATCH 4/8] Prevent installation of an all-zero TK
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Properly track whether a PTK has already been installed to the driver
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and the TK part cleared from memory. This prevents an attacker from
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trying to trick the client into installing an all-zero TK.
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This fixes the earlier fix in commit
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ad00d64e7d8827b3cebd665a0ceb08adabf15e1e ('Fix TK configuration to the
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driver in EAPOL-Key 3/4 retry case') which did not take into account
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possibility of an extra message 1/4 showing up between retries of
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message 3/4.
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Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
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---
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src/common/wpa_common.h | 1 +
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src/rsn_supp/wpa.c | 5 ++---
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src/rsn_supp/wpa_i.h | 1 -
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3 files changed, 3 insertions(+), 4 deletions(-)
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diff --git a/src/common/wpa_common.h b/src/common/wpa_common.h
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index d200285..1021ccb 100644
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--- a/src/common/wpa_common.h
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+++ b/src/common/wpa_common.h
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@@ -215,6 +215,7 @@ struct wpa_ptk {
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size_t kck_len;
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size_t kek_len;
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size_t tk_len;
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+ int installed; /* 1 if key has already been installed to driver */
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};
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struct wpa_gtk {
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diff --git a/src/rsn_supp/wpa.c b/src/rsn_supp/wpa.c
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index 7a2c68d..0550a41 100644
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--- a/src/rsn_supp/wpa.c
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+++ b/src/rsn_supp/wpa.c
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@@ -510,7 +510,6 @@ static void wpa_supplicant_process_1_of_4(struct wpa_sm *sm,
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os_memset(buf, 0, sizeof(buf));
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}
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sm->tptk_set = 1;
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- sm->tk_to_set = 1;
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kde = sm->assoc_wpa_ie;
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kde_len = sm->assoc_wpa_ie_len;
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@@ -615,7 +614,7 @@ static int wpa_supplicant_install_ptk(struct wpa_sm *sm,
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enum wpa_alg alg;
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const u8 *key_rsc;
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- if (!sm->tk_to_set) {
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+ if (sm->ptk.installed) {
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wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
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"WPA: Do not re-install same PTK to the driver");
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return 0;
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@@ -659,7 +658,7 @@ static int wpa_supplicant_install_ptk(struct wpa_sm *sm,
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/* TK is not needed anymore in supplicant */
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os_memset(sm->ptk.tk, 0, WPA_TK_MAX_LEN);
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- sm->tk_to_set = 0;
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+ sm->ptk.installed = 1;
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if (sm->wpa_ptk_rekey) {
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eloop_cancel_timeout(wpa_sm_rekey_ptk, sm, NULL);
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diff --git a/src/rsn_supp/wpa_i.h b/src/rsn_supp/wpa_i.h
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index 9a54631..41f371f 100644
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--- a/src/rsn_supp/wpa_i.h
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+++ b/src/rsn_supp/wpa_i.h
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@@ -24,7 +24,6 @@ struct wpa_sm {
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struct wpa_ptk ptk, tptk;
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int ptk_set, tptk_set;
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unsigned int msg_3_of_4_ok:1;
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- unsigned int tk_to_set:1;
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u8 snonce[WPA_NONCE_LEN];
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u8 anonce[WPA_NONCE_LEN]; /* ANonce from the last 1/4 msg */
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int renew_snonce;
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--
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2.7.4
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