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>

diff --git a/src/common/wpa_common.h b/src/common/wpa_common.h
index 0872b1216fc559c0513a9b3edca0bde7d6ebffa7..8411686f3f7972f0f5c46a18cb17bc20d9eae842 100644 (file)
--- a/src/common/wpa_common.h
+++ b/src/common/wpa_common.h
@@ -219,6 +219,7 @@ 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 acdac173cbf22ff0b9506fb333fd03fec4dbfee0..12e068ac15f6a99a279a03bfda339c7a4b3ab645 100644 (file)
--- a/src/rsn_supp/wpa.c
+++ b/src/rsn_supp/wpa.c
@@ -596,7 +596,6 @@ 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;
@@ -703,7 +702,7 @@ 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;
@@ -747,7 +746,7 @@ 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);
@@ -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. */
        /* TK is not needed anymore in supplicant */
        os_memset(sm->ptk.tk, 0, WPA_TK_MAX_LEN);
+       sm->ptk.installed = 1;
 
        /* FILS HLP Container */
        fils_process_hlp_container(sm, ie_start, end - ie_start);

diff --git a/src/rsn_supp/wpa_i.h b/src/rsn_supp/wpa_i.h
index 5331146dfbc80f17156480197b1978be0460b071..d0963e4d888bd8c3a391481fea9579ba0d8831e4 100644 (file)
--- 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;