Module Name: src
Committed By: christos
Date: Thu Aug 8 08:58:40 UTC 2019
Modified Files:
src/external/bsd/wpa/dist/src/eap_common: eap_pwd_common.c
Log Message:
EAP-pwd: Use const_time_memcmp() for pwd_value >= prime comparison
This reduces timing and memory access pattern differences for an
operation that could depend on the used password.
To generate a diff of this commit:
cvs rdiff -u -r1.3 -r1.4 \
src/external/bsd/wpa/dist/src/eap_common/eap_pwd_common.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/external/bsd/wpa/dist/src/eap_common/eap_pwd_common.c
diff -u src/external/bsd/wpa/dist/src/eap_common/eap_pwd_common.c:1.3 src/external/bsd/wpa/dist/src/eap_common/eap_pwd_common.c:1.4
--- src/external/bsd/wpa/dist/src/eap_common/eap_pwd_common.c:1.3 Wed Apr 10 13:57:15 2019
+++ src/external/bsd/wpa/dist/src/eap_common/eap_pwd_common.c Thu Aug 8 04:58:40 2019
@@ -131,6 +131,7 @@ int compute_password_element(EAP_PWD_gro
u8 qnr_bin[MAX_ECC_PRIME_LEN];
u8 qr_or_qnr_bin[MAX_ECC_PRIME_LEN];
u8 x_bin[MAX_ECC_PRIME_LEN];
+ u8 prime_bin[MAX_ECC_PRIME_LEN];
struct crypto_bignum *tmp1 = NULL, *tmp2 = NULL, *pm1 = NULL;
struct crypto_hash *hash;
unsigned char pwe_digest[SHA256_MAC_LEN], *prfbuf = NULL, ctr;
@@ -148,6 +149,11 @@ int compute_password_element(EAP_PWD_gro
os_memset(x_bin, 0, sizeof(x_bin));
prime = crypto_ec_get_prime(grp->group);
+ primebitlen = crypto_ec_prime_len_bits(grp->group);
+ primebytelen = crypto_ec_prime_len(grp->group);
+ if (crypto_bignum_to_bin(prime, prime_bin, sizeof(prime_bin),
+ primebytelen) < 0)
+ return -1;
cofactor = crypto_bignum_init();
grp->pwe = crypto_ec_point_init(grp->group);
tmp1 = crypto_bignum_init();
@@ -163,8 +169,6 @@ int compute_password_element(EAP_PWD_gro
"curve");
goto fail;
}
- primebitlen = crypto_ec_prime_len_bits(grp->group);
- primebytelen = crypto_ec_prime_len(grp->group);
if ((prfbuf = os_malloc(primebytelen)) == NULL) {
wpa_printf(MSG_INFO, "EAP-pwd: unable to malloc space for prf "
"buffer");
@@ -230,6 +234,8 @@ int compute_password_element(EAP_PWD_gro
if (primebitlen % 8)
buf_shift_right(prfbuf, primebytelen,
8 - primebitlen % 8);
+ if (const_time_memcmp(prfbuf, prime_bin, primebytelen) >= 0)
+ continue;
crypto_bignum_deinit(x_candidate, 1);
x_candidate = crypto_bignum_init_set(prfbuf, primebytelen);
@@ -239,9 +245,6 @@ int compute_password_element(EAP_PWD_gro
goto fail;
}
- if (crypto_bignum_cmp(x_candidate, prime) >= 0)
- continue;
-
wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: x_candidate",
prfbuf, primebytelen);
const_time_select_bin(found, x_bin, prfbuf, primebytelen,
