diff options
Diffstat (limited to 'meta/recipes-connectivity/wpa-supplicant/wpa-supplicant/0006-SAE-Avoid-branches-in-is_quadratic_residue_blind.patch')
| -rw-r--r-- | meta/recipes-connectivity/wpa-supplicant/wpa-supplicant/0006-SAE-Avoid-branches-in-is_quadratic_residue_blind.patch | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/meta/recipes-connectivity/wpa-supplicant/wpa-supplicant/0006-SAE-Avoid-branches-in-is_quadratic_residue_blind.patch b/meta/recipes-connectivity/wpa-supplicant/wpa-supplicant/0006-SAE-Avoid-branches-in-is_quadratic_residue_blind.patch new file mode 100644 index 0000000000..5209559659 --- /dev/null +++ b/meta/recipes-connectivity/wpa-supplicant/wpa-supplicant/0006-SAE-Avoid-branches-in-is_quadratic_residue_blind.patch @@ -0,0 +1,147 @@ +From 362704dda04507e7ebb8035122e83d9f0ae7c320 Mon Sep 17 00:00:00 2001 +From: Jouni Malinen <jouni@codeaurora.org> +Date: Tue, 26 Feb 2019 19:34:38 +0200 +Subject: [PATCH 06/14] SAE: Avoid branches in is_quadratic_residue_blind() + +Make the non-failure path in the function proceed without branches based +on r_odd and in constant time to minimize risk of observable differences +in timing or cache use. (CVE-2019-9494) + +Signed-off-by: Jouni Malinen <jouni@codeaurora.org> +Signed-off-by: Adrian Bunk <bunk@stusta.de> +Upstream-Status: Backport +CVE: CVE-2019-9494 +--- + src/common/sae.c | 64 ++++++++++++++++++++++++++++++++------------------------ + 1 file changed, 37 insertions(+), 27 deletions(-) + +diff --git a/src/common/sae.c b/src/common/sae.c +index d55323b..5df9b95 100644 +--- a/src/common/sae.c ++++ b/src/common/sae.c +@@ -232,12 +232,14 @@ get_rand_1_to_p_1(const u8 *prime, size_t prime_len, size_t prime_bits, + + static int is_quadratic_residue_blind(struct sae_data *sae, + const u8 *prime, size_t bits, +- const struct crypto_bignum *qr, +- const struct crypto_bignum *qnr, ++ const u8 *qr, const u8 *qnr, + const struct crypto_bignum *y_sqr) + { +- struct crypto_bignum *r, *num; ++ struct crypto_bignum *r, *num, *qr_or_qnr = NULL; + int r_odd, check, res = -1; ++ u8 qr_or_qnr_bin[SAE_MAX_ECC_PRIME_LEN]; ++ size_t prime_len = sae->tmp->prime_len; ++ unsigned int mask; + + /* + * Use the blinding technique to mask y_sqr while determining +@@ -248,7 +250,7 @@ static int is_quadratic_residue_blind(struct sae_data *sae, + * r = a random number between 1 and p-1, inclusive + * num = (v * r * r) modulo p + */ +- r = get_rand_1_to_p_1(prime, sae->tmp->prime_len, bits, &r_odd); ++ r = get_rand_1_to_p_1(prime, prime_len, bits, &r_odd); + if (!r) + return -1; + +@@ -258,41 +260,45 @@ static int is_quadratic_residue_blind(struct sae_data *sae, + crypto_bignum_mulmod(num, r, sae->tmp->prime, num) < 0) + goto fail; + +- if (r_odd) { +- /* +- * num = (num * qr) module p +- * LGR(num, p) = 1 ==> quadratic residue +- */ +- if (crypto_bignum_mulmod(num, qr, sae->tmp->prime, num) < 0) +- goto fail; +- check = 1; +- } else { +- /* +- * num = (num * qnr) module p +- * LGR(num, p) = -1 ==> quadratic residue +- */ +- if (crypto_bignum_mulmod(num, qnr, sae->tmp->prime, num) < 0) +- goto fail; +- check = -1; +- } ++ /* ++ * Need to minimize differences in handling different cases, so try to ++ * avoid branches and timing differences. ++ * ++ * If r_odd: ++ * num = (num * qr) module p ++ * LGR(num, p) = 1 ==> quadratic residue ++ * else: ++ * num = (num * qnr) module p ++ * LGR(num, p) = -1 ==> quadratic residue ++ */ ++ mask = const_time_is_zero(r_odd); ++ const_time_select_bin(mask, qnr, qr, prime_len, qr_or_qnr_bin); ++ qr_or_qnr = crypto_bignum_init_set(qr_or_qnr_bin, prime_len); ++ if (!qr_or_qnr || ++ crypto_bignum_mulmod(num, qr_or_qnr, sae->tmp->prime, num) < 0) ++ goto fail; ++ /* r_odd is 0 or 1; branchless version of check = r_odd ? 1 : -1, */ ++ check = const_time_select_int(mask, -1, 1); + + res = crypto_bignum_legendre(num, sae->tmp->prime); + if (res == -2) { + res = -1; + goto fail; + } +- res = res == check; ++ /* branchless version of res = res == check ++ * (res is -1, 0, or 1; check is -1 or 1) */ ++ mask = const_time_eq(res, check); ++ res = const_time_select_int(mask, 1, 0); + fail: + crypto_bignum_deinit(num, 1); + crypto_bignum_deinit(r, 1); ++ crypto_bignum_deinit(qr_or_qnr, 1); + return res; + } + + + static int sae_test_pwd_seed_ecc(struct sae_data *sae, const u8 *pwd_seed, +- const u8 *prime, +- const struct crypto_bignum *qr, +- const struct crypto_bignum *qnr, ++ const u8 *prime, const u8 *qr, const u8 *qnr, + u8 *pwd_value) + { + struct crypto_bignum *y_sqr, *x_cand; +@@ -452,6 +458,8 @@ static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1, + struct crypto_bignum *x = NULL, *qr = NULL, *qnr = NULL; + u8 x_bin[SAE_MAX_ECC_PRIME_LEN]; + u8 x_cand_bin[SAE_MAX_ECC_PRIME_LEN]; ++ u8 qr_bin[SAE_MAX_ECC_PRIME_LEN]; ++ u8 qnr_bin[SAE_MAX_ECC_PRIME_LEN]; + size_t bits; + int res = -1; + u8 found = 0; /* 0 (false) or 0xff (true) to be used as const_time_* +@@ -476,7 +484,9 @@ static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1, + * (qnr) modulo p for blinding purposes during the loop. + */ + if (get_random_qr_qnr(prime, prime_len, sae->tmp->prime, bits, +- &qr, &qnr) < 0) ++ &qr, &qnr) < 0 || ++ crypto_bignum_to_bin(qr, qr_bin, sizeof(qr_bin), prime_len) < 0 || ++ crypto_bignum_to_bin(qnr, qnr_bin, sizeof(qnr_bin), prime_len) < 0) + goto fail; + + wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password", +@@ -527,7 +537,7 @@ static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1, + break; + + res = sae_test_pwd_seed_ecc(sae, pwd_seed, +- prime, qr, qnr, x_cand_bin); ++ prime, qr_bin, qnr_bin, x_cand_bin); + const_time_select_bin(found, x_bin, x_cand_bin, prime_len, + x_bin); + pwd_seed_odd = const_time_select_u8( +-- +2.7.4 + |