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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

12
src/eap_peer/eap_eke.c
View file

@ -414,7 +414,7 @@ static struct wpabuf * eap_eke_process_commit(struct eap_sm *sm,
*/
if (eap_eke_dh_init(data->sess.dhgroup, data->dh_priv, pub) < 0) {
wpa_printf(MSG_INFO, "EAP-EKE: Failed to initialize DH");
os_memset(key, 0, sizeof(key));
forced_memzero(key, sizeof(key));
return eap_eke_build_fail(data, ret, id,
EAP_EKE_FAIL_PRIVATE_INTERNAL_ERROR);
}
@ -422,7 +422,7 @@ static struct wpabuf * eap_eke_process_commit(struct eap_sm *sm,
if (eap_eke_shared_secret(&data->sess, key, data->dh_priv, dhcomp) < 0)
{
wpa_printf(MSG_INFO, "EAP-EKE: Failed to derive shared secret");
os_memset(key, 0, sizeof(key));
forced_memzero(key, sizeof(key));
return eap_eke_build_fail(data, ret, id,
EAP_EKE_FAIL_PRIVATE_INTERNAL_ERROR);
}
@ -431,7 +431,7 @@ static struct wpabuf * eap_eke_process_commit(struct eap_sm *sm,
data->serverid, data->serverid_len,
data->peerid, data->peerid_len) < 0) {
wpa_printf(MSG_INFO, "EAP-EKE: Failed to derive Ke/Ki");
os_memset(key, 0, sizeof(key));
forced_memzero(key, sizeof(key));
return eap_eke_build_fail(data, ret, id,
EAP_EKE_FAIL_PRIVATE_INTERNAL_ERROR);
}
@ -442,7 +442,7 @@ static struct wpabuf * eap_eke_process_commit(struct eap_sm *sm,
data->sess.dhcomp_len + data->sess.pnonce_len,
EAP_EKE_COMMIT);
if (resp == NULL) {
os_memset(key, 0, sizeof(key));
forced_memzero(key, sizeof(key));
return eap_eke_build_fail(data, ret, id,
EAP_EKE_FAIL_PRIVATE_INTERNAL_ERROR);
}
@ -452,11 +452,11 @@ static struct wpabuf * eap_eke_process_commit(struct eap_sm *sm,
if (eap_eke_dhcomp(&data->sess, key, pub, rpos) < 0) {
wpabuf_free(resp);
wpa_printf(MSG_INFO, "EAP-EKE: Failed to build DHComponent_P");
os_memset(key, 0, sizeof(key));
forced_memzero(key, sizeof(key));
return eap_eke_build_fail(data, ret, id,
EAP_EKE_FAIL_PRIVATE_INTERNAL_ERROR);
}
os_memset(key, 0, sizeof(key));
forced_memzero(key, sizeof(key));
wpa_hexdump(MSG_DEBUG, "EAP-EKE: DHComponent_P",
rpos, data->sess.dhcomp_len);

4
src/eap_peer/eap_leap.c
View file

@ -390,8 +390,8 @@ static u8 * eap_leap_getKey(struct eap_sm *sm, void *priv, size_t *len)
wpa_hexdump_key(MSG_DEBUG, "EAP-LEAP: master key", key, LEAP_KEY_LEN);
*len = LEAP_KEY_LEN;
os_memset(pw_hash, 0, sizeof(pw_hash));
os_memset(pw_hash_hash, 0, sizeof(pw_hash_hash));
forced_memzero(pw_hash, sizeof(pw_hash));
forced_memzero(pw_hash_hash, sizeof(pw_hash_hash));
return key;
}

6
src/eap_peer/eap_peap.c
View file

@ -295,7 +295,7 @@ static int eap_peap_derive_cmk(struct eap_sm *sm, struct eap_peap_data *data)
res = peap_prfplus(data->peap_version, tk, 40,
"Inner Methods Compound Keys",
isk, sizeof(isk), imck, sizeof(imck));
os_memset(isk, 0, sizeof(isk));
forced_memzero(isk, sizeof(isk));
if (res < 0)
return -1;
wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: IMCK (IPMKj)",
@ -305,7 +305,7 @@ static int eap_peap_derive_cmk(struct eap_sm *sm, struct eap_peap_data *data)
wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: IPMK (S-IPMKj)", data->ipmk, 40);
os_memcpy(data->cmk, imck + 40, 20);
wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: CMK (CMKj)", data->cmk, 20);
os_memset(imck, 0, sizeof(imck));
forced_memzero(imck, sizeof(imck));
return 0;
}
@ -1267,7 +1267,7 @@ static u8 * eap_peap_getKey(struct eap_sm *sm, void *priv, size_t *len)
os_memcpy(key, csk, EAP_TLS_KEY_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PEAP: Derived key",
key, EAP_TLS_KEY_LEN);
os_memset(csk, 0, sizeof(csk));
forced_memzero(csk, sizeof(csk));
} else
os_memcpy(key, data->key_data, EAP_TLS_KEY_LEN);

6
src/eap_peer/eap_pwd.c
View file

@ -362,7 +362,7 @@ eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
data->password_len, pwhash);
if (res == 0)
res = hash_nt_password_hash(pwhash, pwhashhash);
os_memset(pwhash, 0, sizeof(pwhash));
forced_memzero(pwhash, sizeof(pwhash));
}
if (res) {
@ -514,8 +514,8 @@ eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
data->id_server, data->id_server_len,
data->id_peer, data->id_peer_len,
data->token);
os_memset(pwhashhash, 0, sizeof(pwhashhash));
os_memset(salthashpwd, 0, sizeof(salthashpwd));
forced_memzero(pwhashhash, sizeof(pwhashhash));
forced_memzero(salthashpwd, sizeof(salthashpwd));
if (res) {
wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
eap_pwd_state(data, FAILURE);