--- /dev/null
+From 6c4bed4f47d1960ec04981a9d50e5076aea5223d Mon Sep 17 00:00:00 2001
+From: Jouni Malinen <j@w1.fi>
+Date: Fri, 22 Sep 2017 11:03:15 +0300
+Subject: [PATCH 6/8] TDLS: Reject TPK-TK reconfiguration
+
+Do not try to reconfigure the same TPK-TK to the driver after it has
+been successfully configured. This is an explicit check to avoid issues
+related to resetting the TX/RX packet number. There was already a check
+for this for TPK M2 (retries of that message are ignored completely), so
+that behavior does not get modified.
+
+For TPK M3, the TPK-TK could have been reconfigured, but that was
+followed by immediate teardown of the link due to an issue in updating
+the STA entry. Furthermore, for TDLS with any real security (i.e.,
+ignoring open/WEP), the TPK message exchange is protected on the AP path
+and simple replay attacks are not feasible.
+
+As an additional corner case, make sure the local nonce gets updated if
+the peer uses a very unlikely "random nonce" of all zeros.
+
+Signed-off-by: Jouni Malinen <j@w1.fi>
+---
+ src/rsn_supp/tdls.c | 38 ++++++++++++++++++++++++++++++++++++--
+ 1 file changed, 36 insertions(+), 2 deletions(-)
+
+diff --git a/src/rsn_supp/tdls.c b/src/rsn_supp/tdls.c
+index e424168..9eb9738 100644
+--- a/src/rsn_supp/tdls.c
++++ b/src/rsn_supp/tdls.c
+@@ -112,6 +112,7 @@ struct wpa_tdls_peer {
+ u8 tk[16]; /* TPK-TK; assuming only CCMP will be used */
+ } tpk;
+ int tpk_set;
++ int tk_set; /* TPK-TK configured to the driver */
+ int tpk_success;
+ int tpk_in_progress;
+
+@@ -192,6 +193,20 @@ static int wpa_tdls_set_key(struct wpa_sm *sm, struct wpa_tdls_peer *peer)
+ u8 rsc[6];
+ enum wpa_alg alg;
+
++ if (peer->tk_set) {
++ /*
++ * This same TPK-TK has already been configured to the driver
++ * and this new configuration attempt (likely due to an
++ * unexpected retransmitted frame) would result in clearing
++ * the TX/RX sequence number which can break security, so must
++ * not allow that to happen.
++ */
++ wpa_printf(MSG_INFO, "TDLS: TPK-TK for the peer " MACSTR
++ " has already been configured to the driver - do not reconfigure",
++ MAC2STR(peer->addr));
++ return -1;
++ }
++
+ os_memset(rsc, 0, 6);
+
+ switch (peer->cipher) {
+@@ -209,12 +224,15 @@ static int wpa_tdls_set_key(struct wpa_sm *sm, struct wpa_tdls_peer *peer)
+ return -1;
+ }
+
++ wpa_printf(MSG_DEBUG, "TDLS: Configure pairwise key for peer " MACSTR,
++ MAC2STR(peer->addr));
+ if (wpa_sm_set_key(sm, alg, peer->addr, -1, 1,
+ rsc, sizeof(rsc), peer->tpk.tk, key_len) < 0) {
+ wpa_printf(MSG_WARNING, "TDLS: Failed to set TPK to the "
+ "driver");
+ return -1;
+ }
++ peer->tk_set = 1;
+ return 0;
+ }
+
+@@ -696,7 +714,7 @@ static void wpa_tdls_peer_clear(struct wpa_sm *sm, struct wpa_tdls_peer *peer)
+ peer->cipher = 0;
+ peer->qos_info = 0;
+ peer->wmm_capable = 0;
+- peer->tpk_set = peer->tpk_success = 0;
++ peer->tk_set = peer->tpk_set = peer->tpk_success = 0;
+ peer->chan_switch_enabled = 0;
+ os_memset(&peer->tpk, 0, sizeof(peer->tpk));
+ os_memset(peer->inonce, 0, WPA_NONCE_LEN);
+@@ -1159,6 +1177,7 @@ skip_rsnie:
+ wpa_tdls_peer_free(sm, peer);
+ return -1;
+ }
++ peer->tk_set = 0; /* A new nonce results in a new TK */
+ wpa_hexdump(MSG_DEBUG, "TDLS: Initiator Nonce for TPK handshake",
+ peer->inonce, WPA_NONCE_LEN);
+ os_memcpy(ftie->Snonce, peer->inonce, WPA_NONCE_LEN);
+@@ -1751,6 +1770,19 @@ static int wpa_tdls_addset_peer(struct wpa_sm *sm, struct wpa_tdls_peer *peer,
+ }
+
+
++static int tdls_nonce_set(const u8 *nonce)
++{
++ int i;
++
++ for (i = 0; i < WPA_NONCE_LEN; i++) {
++ if (nonce[i])
++ return 1;
++ }
++
++ return 0;
++}
++
++
+ static int wpa_tdls_process_tpk_m1(struct wpa_sm *sm, const u8 *src_addr,
+ const u8 *buf, size_t len)
+ {
+@@ -2004,7 +2036,8 @@ skip_rsn:
+ peer->rsnie_i_len = kde.rsn_ie_len;
+ peer->cipher = cipher;
+
+- if (os_memcmp(peer->inonce, ftie->Snonce, WPA_NONCE_LEN) != 0) {
++ if (os_memcmp(peer->inonce, ftie->Snonce, WPA_NONCE_LEN) != 0 ||
++ !tdls_nonce_set(peer->inonce)) {
+ /*
+ * There is no point in updating the RNonce for every obtained
+ * TPK M1 frame (e.g., retransmission due to timeout) with the
+@@ -2020,6 +2053,7 @@ skip_rsn:
+ "TDLS: Failed to get random data for responder nonce");
+ goto error;
+ }
++ peer->tk_set = 0; /* A new nonce results in a new TK */
+ }
+
+ #if 0
+--
+2.7.4
+
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