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