wpa_supplicant: Move SAE modules into dragonfly files

components/wpa_supplicant/CMakeLists.txt

@@ -6,6 +6,7 @@ set(srcs "port/os_xtensa.c"
     "src/ap/wpa_auth_ie.c"
     "src/ap/sta_info.c"
     "src/common/sae.c"
+    "src/common/dragonfly.c"
     "src/common/wpa_common.c"
     "src/utils/bitfield.c"
     "src/crypto/aes-siv.c"

components/wpa_supplicant/src/common/dragonfly.c

@@ -0,0 +1,249 @@
+/*
+ * Shared Dragonfly functionality
+ * Copyright (c) 2012-2016, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2019, The Linux Foundation
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+
+#include "utils/common.h"
+#include "utils/const_time.h"
+#include "crypto/crypto.h"
+#include "dragonfly.h"
+
+
+int dragonfly_suitable_group(int group, int ecc_only)
+{
+	/* Enforce REVmd rules on which SAE groups are suitable for production
+	 * purposes: FFC groups whose prime is >= 3072 bits and ECC groups
+	 * defined over a prime field whose prime is >= 256 bits. Furthermore,
+	 * ECC groups defined over a characteristic 2 finite field and ECC
+	 * groups with a co-factor greater than 1 are not suitable. Disable
+	 * groups that use Brainpool curves as well for now since they leak more
+	 * timing information due to the prime not being close to a power of
+	 * two. */
+	return group == 19 || group == 20 || group == 21 ||
+		(!ecc_only &&
+		 (group == 15 || group == 16 || group == 17 || group == 18));
+}
+
+
+unsigned int dragonfly_min_pwe_loop_iter(int group)
+{
+	if (group == 22 || group == 23 || group == 24) {
+		/* FFC groups for which pwd-value is likely to be >= p
+		 * frequently */
+		return 40;
+	}
+
+	if (group == 1 || group == 2 || group == 5 || group == 14 ||
+	    group == 15 || group == 16 || group == 17 || group == 18) {
+		/* FFC groups that have prime that is close to a power of two */
+		return 1;
+	}
+
+	/* Default to 40 (this covers most ECC groups) */
+	return 40;
+}
+
+
+int dragonfly_get_random_qr_qnr(const struct crypto_bignum *prime,
+				struct crypto_bignum **qr,
+				struct crypto_bignum **qnr)
+{
+	*qr = *qnr = NULL;
+
+	while (!(*qr) || !(*qnr)) {
+		struct crypto_bignum *tmp;
+		int res;
+
+		tmp = crypto_bignum_init();
+		if (!tmp || crypto_bignum_rand(tmp, prime) < 0) {
+			crypto_bignum_deinit(tmp, 0);
+			break;
+		}
+
+		res = crypto_bignum_legendre(tmp, prime);
+		if (res == 1 && !(*qr))
+			*qr = tmp;
+		else if (res == -1 && !(*qnr))
+			*qnr = tmp;
+		else
+			crypto_bignum_deinit(tmp, 0);
+	}
+
+	if (*qr && *qnr)
+		return 0;
+	crypto_bignum_deinit(*qr, 0);
+	crypto_bignum_deinit(*qnr, 0);
+	*qr = *qnr = NULL;
+	return -1;
+}
+
+
+static struct crypto_bignum *
+dragonfly_get_rand_1_to_p_1(const struct crypto_bignum *prime)
+{
+	struct crypto_bignum *tmp, *pm1, *one;
+
+	tmp = crypto_bignum_init();
+	pm1 = crypto_bignum_init();
+	one = crypto_bignum_init_set((const u8 *) "\x01", 1);
+	if (!tmp || !pm1 || !one ||
+	    crypto_bignum_sub(prime, one, pm1) < 0 ||
+	    crypto_bignum_rand(tmp, pm1) < 0 ||
+	    crypto_bignum_add(tmp, one, tmp) < 0) {
+		crypto_bignum_deinit(tmp, 0);
+		tmp = NULL;
+	}
+
+	crypto_bignum_deinit(pm1, 0);
+	crypto_bignum_deinit(one, 0);
+	return tmp;
+}
+
+
+int dragonfly_is_quadratic_residue_blind(struct crypto_ec *ec,
+					 const u8 *qr, const u8 *qnr,
+					 const struct crypto_bignum *val)
+{
+	struct crypto_bignum *r, *num, *qr_or_qnr = NULL;
+	int check, res = -1;
+	u8 qr_or_qnr_bin[DRAGONFLY_MAX_ECC_PRIME_LEN];
+	const struct crypto_bignum *prime;
+	size_t prime_len;
+	unsigned int mask;
+
+	prime = crypto_ec_get_prime(ec);
+	prime_len = crypto_ec_prime_len(ec);
+
+	/*
+	 * Use a blinding technique to mask val while determining whether it is
+	 * a quadratic residue modulo p to avoid leaking timing information
+	 * while determining the Legendre symbol.
+	 *
+	 * v = val
+	 * r = a random number between 1 and p-1, inclusive
+	 * num = (v * r * r) modulo p
+	 */
+	r = dragonfly_get_rand_1_to_p_1(prime);
+	if (!r)
+		return -1;
+
+	num = crypto_bignum_init();
+	if (!num ||
+	    crypto_bignum_mulmod(val, r, prime, num) < 0 ||
+	    crypto_bignum_mulmod(num, r, prime, num) < 0)
+		goto fail;
+
+	/*
+	 * Need to minimize differences in handling different cases, so try to
+	 * avoid branches and timing differences.
+	 *
+	 * If r is 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 is set to !odd(r)
+	 */
+	mask = const_time_is_zero(crypto_bignum_is_odd(r));
+	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, prime, num) < 0)
+		goto fail;
+	/* branchless version of check = odd(r) ? 1 : -1, */
+	check = const_time_select_int(mask, -1, 1);
+
+	/* Determine the Legendre symbol on the masked value */
+	res = crypto_bignum_legendre(num, prime);
+	if (res == -2) {
+		res = -1;
+		goto fail;
+	}
+	/* 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 dragonfly_get_rand_2_to_r_1(struct crypto_bignum *val,
+				       const struct crypto_bignum *order)
+{
+	return crypto_bignum_rand(val, order) == 0 &&
+		!crypto_bignum_is_zero(val) &&
+		!crypto_bignum_is_one(val);
+}
+
+
+int dragonfly_generate_scalar(const struct crypto_bignum *order,
+			      struct crypto_bignum *_rand,
+			      struct crypto_bignum *_mask,
+			      struct crypto_bignum *scalar)
+{
+	int count;
+
+	/* Select two random values rand,mask such that 1 < rand,mask < r and
+	 * rand + mask mod r > 1. */
+	for (count = 0; count < 100; count++) {
+		if (dragonfly_get_rand_2_to_r_1(_rand, order) &&
+		    dragonfly_get_rand_2_to_r_1(_mask, order) &&
+		    crypto_bignum_add(_rand, _mask, scalar) == 0 &&
+		    crypto_bignum_mod(scalar, order, scalar) == 0 &&
+		    !crypto_bignum_is_zero(scalar) &&
+		    !crypto_bignum_is_one(scalar))
+			return 0;
+	}
+
+	/* This should not be reachable in practice if the random number
+	 * generation is working. */
+	wpa_printf(MSG_INFO,
+		   "dragonfly: Unable to get randomness for own scalar");
+	return -1;
+}
+
+
+/* res = sqrt(val) */
+int dragonfly_sqrt(struct crypto_ec *ec, const struct crypto_bignum *val,
+		   struct crypto_bignum *res)
+{
+	const struct crypto_bignum *prime;
+	struct crypto_bignum *tmp, *one;
+	int ret = 0;
+	u8 prime_bin[DRAGONFLY_MAX_ECC_PRIME_LEN];
+	size_t prime_len;
+
+	/* For prime p such that p = 3 mod 4, sqrt(w) = w^((p+1)/4) mod p */
+
+	prime = crypto_ec_get_prime(ec);
+	prime_len = crypto_ec_prime_len(ec);
+	tmp = crypto_bignum_init();
+	one = crypto_bignum_init_uint(1);
+
+	if (crypto_bignum_to_bin(prime, prime_bin, sizeof(prime_bin),
+				 prime_len) < 0 ||
+	    (prime_bin[prime_len - 1] & 0x03) != 3 ||
+	    !tmp || !one ||
+	    /* tmp = (p+1)/4 */
+	    crypto_bignum_add(prime, one, tmp) < 0 ||
+	    crypto_bignum_rshift(tmp, 2, tmp) < 0 ||
+	    /* res = sqrt(val) */
+	    crypto_bignum_exptmod(val, tmp, prime, res) < 0)
+		ret = -1;
+
+	crypto_bignum_deinit(tmp, 0);
+	crypto_bignum_deinit(one, 0);
+	return ret;
+}

components/wpa_supplicant/src/common/dragonfly.h

@@ -0,0 +1,33 @@
+/*
+ * Shared Dragonfly functionality
+ * Copyright (c) 2012-2016, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2019, The Linux Foundation
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#ifndef DRAGONFLY_H
+#define DRAGONFLY_H
+
+#define DRAGONFLY_MAX_ECC_PRIME_LEN 66
+
+struct crypto_bignum;
+struct crypto_ec;
+
+int dragonfly_suitable_group(int group, int ecc_only);
+unsigned int dragonfly_min_pwe_loop_iter(int group);
+int dragonfly_get_random_qr_qnr(const struct crypto_bignum *prime,
+				struct crypto_bignum **qr,
+				struct crypto_bignum **qnr);
+int dragonfly_is_quadratic_residue_blind(struct crypto_ec *ec,
+					 const u8 *qr, const u8 *qnr,
+					 const struct crypto_bignum *val);
+int dragonfly_generate_scalar(const struct crypto_bignum *order,
+			      struct crypto_bignum *_rand,
+			      struct crypto_bignum *_mask,
+			      struct crypto_bignum *scalar);
+int dragonfly_sqrt(struct crypto_ec *ec, const struct crypto_bignum *val,
+		   struct crypto_bignum *res);
+
+#endif /* DRAGONFLY_H */