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More forceful clearing of stack memory with keys

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gcc 8.3.0 was apparently clever enough to optimize away the previously
used os_memset() to explicitly clear a stack buffer that contains keys
when that clearing happened just before returning from the function.
Since memset_s() is not exactly portable (or commonly available yet..),
use a less robust mechanism that is still pretty likely to prevent
current compilers from optimizing the explicit clearing of the memory
away.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2019-05-26 00:47:17 +03:00
parent e1923f5b6a
commit 31bc66e4d1
25 changed files with 98 additions and 72 deletions
Download patch file Download diff file Expand all files Collapse all files

38
src/rsn_supp/wpa.c
View file

@ -334,7 +334,7 @@ static int wpa_supplicant_get_pmk(struct wpa_sm *sm,
os_memcpy(sm->xxkey, buf + PMK_LEN, PMK_LEN);
sm->xxkey_len = PMK_LEN;
}
os_memset(buf, 0, sizeof(buf));
forced_memzero(buf, sizeof(buf));
if (sm->proto == WPA_PROTO_RSN &&
wpa_key_mgmt_ft(sm->key_mgmt)) {
struct rsn_pmksa_cache_entry *sa = NULL;
@ -649,7 +649,7 @@ static void wpa_supplicant_process_1_of_4(struct wpa_sm *sm,
os_memcpy(buf, &ptk->tk[16], 8);
os_memcpy(&ptk->tk[16], &ptk->tk[24], 8);
os_memcpy(&ptk->tk[24], buf, 8);
os_memset(buf, 0, sizeof(buf));
forced_memzero(buf, sizeof(buf));
}
sm->tptk_set = 1;
@ -923,7 +923,7 @@ static int wpa_supplicant_install_gtk(struct wpa_sm *sm,
wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
"WPA: Failed to set GTK to the driver "
"(Group only)");
os_memset(gtk_buf, 0, sizeof(gtk_buf));
forced_memzero(gtk_buf, sizeof(gtk_buf));
return -1;
}
} else if (wpa_sm_set_key(sm, gd->alg, broadcast_ether_addr,
@ -933,10 +933,10 @@ static int wpa_supplicant_install_gtk(struct wpa_sm *sm,
"WPA: Failed to set GTK to "
"the driver (alg=%d keylen=%d keyidx=%d)",
gd->alg, gd->gtk_len, gd->keyidx);
os_memset(gtk_buf, 0, sizeof(gtk_buf));
forced_memzero(gtk_buf, sizeof(gtk_buf));
return -1;
}
os_memset(gtk_buf, 0, sizeof(gtk_buf));
forced_memzero(gtk_buf, sizeof(gtk_buf));
if (wnm_sleep) {
sm->gtk_wnm_sleep.gtk_len = gd->gtk_len;
@ -1042,10 +1042,10 @@ static int wpa_supplicant_pairwise_gtk(struct wpa_sm *sm,
wpa_supplicant_install_gtk(sm, &gd, key_rsc, 0))) {
wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
"RSN: Failed to install GTK");
os_memset(&gd, 0, sizeof(gd));
forced_memzero(&gd, sizeof(gd));
return -1;
}
os_memset(&gd, 0, sizeof(gd));
forced_memzero(&gd, sizeof(gd));
return 0;
}
@ -1714,12 +1714,12 @@ static int wpa_supplicant_process_1_of_2_wpa(struct wpa_sm *sm,
os_memcpy(ek + 16, sm->ptk.kek, sm->ptk.kek_len);
os_memcpy(gd->gtk, key_data, key_data_len);
if (rc4_skip(ek, 32, 256, gd->gtk, key_data_len)) {
os_memset(ek, 0, sizeof(ek));
forced_memzero(ek, sizeof(ek));
wpa_msg(sm->ctx->msg_ctx, MSG_ERROR,
"WPA: RC4 failed");
return -1;
}
os_memset(ek, 0, sizeof(ek));
forced_memzero(ek, sizeof(ek));
#endif /* CONFIG_NO_RC4 */
} else if (ver == WPA_KEY_INFO_TYPE_HMAC_SHA1_AES) {
if (maxkeylen % 8) {
@ -1868,7 +1868,7 @@ static void wpa_supplicant_process_1_of_2(struct wpa_sm *sm,
if (wpa_supplicant_install_gtk(sm, &gd, key_rsc, 0) ||
wpa_supplicant_send_2_of_2(sm, key, ver, key_info) < 0)
goto failed;
os_memset(&gd, 0, sizeof(gd));
forced_memzero(&gd, sizeof(gd));
if (rekey) {
wpa_msg(sm->ctx->msg_ctx, MSG_INFO, "WPA: Group rekeying "
@ -1887,7 +1887,7 @@ static void wpa_supplicant_process_1_of_2(struct wpa_sm *sm,
return;
failed:
os_memset(&gd, 0, sizeof(gd));
forced_memzero(&gd, sizeof(gd));
wpa_sm_deauthenticate(sm, WLAN_REASON_UNSPECIFIED);
}
@ -2001,12 +2001,12 @@ static int wpa_supplicant_decrypt_key_data(struct wpa_sm *sm,
os_memcpy(ek, key->key_iv, 16);
os_memcpy(ek + 16, sm->ptk.kek, sm->ptk.kek_len);
if (rc4_skip(ek, 32, 256, key_data, *key_data_len)) {
os_memset(ek, 0, sizeof(ek));
forced_memzero(ek, sizeof(ek));
wpa_msg(sm->ctx->msg_ctx, MSG_ERROR,
"WPA: RC4 failed");
return -1;
}
os_memset(ek, 0, sizeof(ek));
forced_memzero(ek, sizeof(ek));
#endif /* CONFIG_NO_RC4 */
} else if (ver == WPA_KEY_INFO_TYPE_HMAC_SHA1_AES ||
ver == WPA_KEY_INFO_TYPE_AES_128_CMAC ||
@ -3446,12 +3446,12 @@ int wpa_wnmsleep_install_key(struct wpa_sm *sm, u8 subelem_id, u8 *buf)
wpa_hexdump_key(MSG_DEBUG, "Install GTK (WNM SLEEP)",
gd.gtk, gd.gtk_len);
if (wpa_supplicant_install_gtk(sm, &gd, key_rsc, 1)) {
os_memset(&gd, 0, sizeof(gd));
forced_memzero(&gd, sizeof(gd));
wpa_printf(MSG_DEBUG, "Failed to install the GTK in "
"WNM mode");
return -1;
}
os_memset(&gd, 0, sizeof(gd));
forced_memzero(&gd, sizeof(gd));
#ifdef CONFIG_IEEE80211W
} else if (subelem_id == WNM_SLEEP_SUBELEM_IGTK) {
const struct wpa_igtk_kde *igtk;
@ -3881,7 +3881,7 @@ int fils_process_auth(struct wpa_sm *sm, const u8 *bssid, const u8 *data,
dh_ss ? wpabuf_head(dh_ss) : NULL,
dh_ss ? wpabuf_len(dh_ss) : 0,
sm->pmk, &sm->pmk_len);
os_memset(rmsk, 0, sizeof(rmsk));
forced_memzero(rmsk, sizeof(rmsk));
/* Don't use DHss in PTK derivation if PMKSA caching is not
* used. */
@ -3956,7 +3956,7 @@ int fils_process_auth(struct wpa_sm *sm, const u8 *bssid, const u8 *data,
sm->fils_key_auth_ap,
&sm->fils_key_auth_len);
wpabuf_free(pub);
os_memset(ick, 0, sizeof(ick));
forced_memzero(ick, sizeof(ick));
return res;
fail:
wpabuf_free(pub);
@ -4480,9 +4480,11 @@ int fils_process_assoc_resp(struct wpa_sm *sm, const u8 *resp, size_t len)
wpa_printf(MSG_DEBUG, "FILS: Auth+Assoc completed successfully");
sm->fils_completed = 1;
forced_memzero(&gd, sizeof(gd));
return 0;
fail:
forced_memzero(&gd, sizeof(gd));
return -1;
}
@ -4694,7 +4696,7 @@ int owe_process_assoc_resp(struct wpa_sm *sm, const u8 *bssid,
else if (group == 21)
res = hmac_sha512_kdf(prk, hash_len, NULL, (const u8 *) info,
os_strlen(info), sm->pmk, hash_len);
os_memset(prk, 0, SHA512_MAC_LEN);
forced_memzero(prk, SHA512_MAC_LEN);
if (res < 0) {
sm->pmk_len = 0;
return -1;

4
src/rsn_supp/wpa_ft.c
View file

@ -828,10 +828,10 @@ static int wpa_ft_process_igtk_subelem(struct wpa_sm *sm, const u8 *igtk_elem,
igtk_elem + 2, 6, igtk, igtk_len) < 0) {
wpa_printf(MSG_WARNING, "WPA: Failed to set IGTK to the "
"driver.");
os_memset(igtk, 0, sizeof(igtk));
forced_memzero(igtk, sizeof(igtk));
return -1;
}
os_memset(igtk, 0, sizeof(igtk));
forced_memzero(igtk, sizeof(igtk));
return 0;
}