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Prevent installation of an all-zero TK

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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
ad00d64e7d ('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>
This commit is contained in:
Mathy Vanhoef 2017-09-29 04:22:51 +02:00 committed by Jouni Malinen
parent 87e2db16ba
commit 53bb18cc8b
3 changed files with 4 additions and 4 deletions
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1
src/common/wpa_common.h
View file

@ -219,6 +219,7 @@ struct wpa_ptk {
size_t kck_len; size_t kck_len;
size_t kek_len; size_t kek_len;
size_t tk_len; size_t tk_len;
int installed; /* 1 if key has already been installed to driver */
}; };
struct wpa_gtk { struct wpa_gtk {

6
src/rsn_supp/wpa.c
View file

@ -596,7 +596,6 @@ static void wpa_supplicant_process_1_of_4(struct wpa_sm *sm,
os_memset(buf, 0, sizeof(buf)); os_memset(buf, 0, sizeof(buf));
} }
sm->tptk_set = 1; sm->tptk_set = 1;
sm->tk_to_set = 1;
kde = sm->assoc_wpa_ie; kde = sm->assoc_wpa_ie;
kde_len = sm->assoc_wpa_ie_len; kde_len = sm->assoc_wpa_ie_len;
@ -703,7 +702,7 @@ static int wpa_supplicant_install_ptk(struct wpa_sm *sm,
enum wpa_alg alg; enum wpa_alg alg;
const u8 *key_rsc; const u8 *key_rsc;
if (!sm->tk_to_set) { if (sm->ptk.installed) {
wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG, wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
"WPA: Do not re-install same PTK to the driver"); "WPA: Do not re-install same PTK to the driver");
return 0; return 0;
@ -747,7 +746,7 @@ static int wpa_supplicant_install_ptk(struct wpa_sm *sm,
/* TK is not needed anymore in supplicant */ /* TK is not needed anymore in supplicant */
os_memset(sm->ptk.tk, 0, WPA_TK_MAX_LEN); os_memset(sm->ptk.tk, 0, WPA_TK_MAX_LEN);
sm->tk_to_set = 0; sm->ptk.installed = 1;
if (sm->wpa_ptk_rekey) { if (sm->wpa_ptk_rekey) {
eloop_cancel_timeout(wpa_sm_rekey_ptk, sm, NULL); eloop_cancel_timeout(wpa_sm_rekey_ptk, sm, NULL);
@ -4185,6 +4184,7 @@ int fils_process_assoc_resp(struct wpa_sm *sm, const u8 *resp, size_t len)
* takes care of association frame encryption/decryption. */ * takes care of association frame encryption/decryption. */
/* TK is not needed anymore in supplicant */ /* TK is not needed anymore in supplicant */
os_memset(sm->ptk.tk, 0, WPA_TK_MAX_LEN); os_memset(sm->ptk.tk, 0, WPA_TK_MAX_LEN);
sm->ptk.installed = 1;
/* FILS HLP Container */ /* FILS HLP Container */
fils_process_hlp_container(sm, ie_start, end - ie_start); fils_process_hlp_container(sm, ie_start, end - ie_start);

1
src/rsn_supp/wpa_i.h
View file

@ -24,7 +24,6 @@ struct wpa_sm {
struct wpa_ptk ptk, tptk; struct wpa_ptk ptk, tptk;
int ptk_set, tptk_set; int ptk_set, tptk_set;
unsigned int msg_3_of_4_ok:1; unsigned int msg_3_of_4_ok:1;
unsigned int tk_to_set:1;
u8 snonce[WPA_NONCE_LEN]; u8 snonce[WPA_NONCE_LEN];
u8 anonce[WPA_NONCE_LEN]; /* ANonce from the last 1/4 msg */ u8 anonce[WPA_NONCE_LEN]; /* ANonce from the last 1/4 msg */
int renew_snonce; int renew_snonce;