[people/ms/u-boot.git] / lib / rsa / rsa-verify.c

/*
 * Copyright (c) 2013, Google Inc.
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#ifndef USE_HOSTCC
#include <common.h>
#include <fdtdec.h>
#include <asm/types.h>
#include <asm/byteorder.h>
#include <asm/errno.h>
#include <asm/types.h>
#include <asm/unaligned.h>
#else
#include "fdt_host.h"
#include "mkimage.h"
#include <fdt_support.h>
#endif
#include <u-boot/rsa.h>
#include <u-boot/sha1.h>
#include <u-boot/sha256.h>

#define UINT64_MULT32(v, multby)  (((uint64_t)(v)) * ((uint32_t)(multby)))

#define get_unaligned_be32(a) fdt32_to_cpu(*(uint32_t *)a)
#define put_unaligned_be32(a, b) (*(uint32_t *)(b) = cpu_to_fdt32(a))

/* Default public exponent for backward compatibility */
#define RSA_DEFAULT_PUBEXP	65537

/**
 * subtract_modulus() - subtract modulus from the given value
 *
 * @key:	Key containing modulus to subtract
 * @num:	Number to subtract modulus from, as little endian word array
 */
static void subtract_modulus(const struct rsa_public_key *key, uint32_t num[])
{
	int64_t acc = 0;
	uint i;

	for (i = 0; i < key->len; i++) {
		acc += (uint64_t)num[i] - key->modulus[i];
		num[i] = (uint32_t)acc;
		acc >>= 32;
	}
}

/**
 * greater_equal_modulus() - check if a value is >= modulus
 *
 * @key:	Key containing modulus to check
 * @num:	Number to check against modulus, as little endian word array
 * @return 0 if num < modulus, 1 if num >= modulus
 */
static int greater_equal_modulus(const struct rsa_public_key *key,
				 uint32_t num[])
{
	uint32_t i;

	for (i = key->len - 1; i >= 0; i--) {
		if (num[i] < key->modulus[i])
			return 0;
		if (num[i] > key->modulus[i])
			return 1;
	}

	return 1;  /* equal */
}

/**
 * montgomery_mul_add_step() - Perform montgomery multiply-add step
 *
 * Operation: montgomery result[] += a * b[] / n0inv % modulus
 *
 * @key:	RSA key
 * @result:	Place to put result, as little endian word array
 * @a:		Multiplier
 * @b:		Multiplicand, as little endian word array
 */
static void montgomery_mul_add_step(const struct rsa_public_key *key,
		uint32_t result[], const uint32_t a, const uint32_t b[])
{
	uint64_t acc_a, acc_b;
	uint32_t d0;
	uint i;

	acc_a = (uint64_t)a * b[0] + result[0];
	d0 = (uint32_t)acc_a * key->n0inv;
	acc_b = (uint64_t)d0 * key->modulus[0] + (uint32_t)acc_a;
	for (i = 1; i < key->len; i++) {
		acc_a = (acc_a >> 32) + (uint64_t)a * b[i] + result[i];
		acc_b = (acc_b >> 32) + (uint64_t)d0 * key->modulus[i] +
				(uint32_t)acc_a;
		result[i - 1] = (uint32_t)acc_b;
	}

	acc_a = (acc_a >> 32) + (acc_b >> 32);

	result[i - 1] = (uint32_t)acc_a;

	if (acc_a >> 32)
		subtract_modulus(key, result);
}

/**
 * montgomery_mul() - Perform montgomery mutitply
 *
 * Operation: montgomery result[] = a[] * b[] / n0inv % modulus
 *
 * @key:	RSA key
 * @result:	Place to put result, as little endian word array
 * @a:		Multiplier, as little endian word array
 * @b:		Multiplicand, as little endian word array
 */
static void montgomery_mul(const struct rsa_public_key *key,
		uint32_t result[], uint32_t a[], const uint32_t b[])
{
	uint i;

	for (i = 0; i < key->len; ++i)
		result[i] = 0;
	for (i = 0; i < key->len; ++i)
		montgomery_mul_add_step(key, result, a[i], b);
}

/**
 * num_pub_exponent_bits() - Number of bits in the public exponent
 *
 * @key:	RSA key
 * @num_bits:	Storage for the number of public exponent bits
 */
static int num_public_exponent_bits(const struct rsa_public_key *key,
		int *num_bits)
{
	uint64_t exponent;
	int exponent_bits;
	const uint max_bits = (sizeof(exponent) * 8);

	exponent = key->exponent;
	exponent_bits = 0;

	if (!exponent) {
		*num_bits = exponent_bits;
		return 0;
	}

	for (exponent_bits = 1; exponent_bits < max_bits + 1; ++exponent_bits)
		if (!(exponent >>= 1)) {
			*num_bits = exponent_bits;
			return 0;
		}

	return -EINVAL;
}

/**
 * is_public_exponent_bit_set() - Check if a bit in the public exponent is set
 *
 * @key:	RSA key
 * @pos:	The bit position to check
 */
static int is_public_exponent_bit_set(const struct rsa_public_key *key,
		int pos)
{
	return key->exponent & (1ULL << pos);
}

/**
 * pow_mod() - in-place public exponentiation
 *
 * @key:	RSA key
 * @inout:	Big-endian word array containing value and result
 */
static int pow_mod(const struct rsa_public_key *key, uint32_t *inout)
{
	uint32_t *result, *ptr;
	uint i;
	int j, k;

	/* Sanity check for stack size - key->len is in 32-bit words */
	if (key->len > RSA_MAX_KEY_BITS / 32) {
		debug("RSA key words %u exceeds maximum %d\n", key->len,
		      RSA_MAX_KEY_BITS / 32);
		return -EINVAL;
	}

	uint32_t val[key->len], acc[key->len], tmp[key->len];
	uint32_t a_scaled[key->len];
	result = tmp;  /* Re-use location. */

	/* Convert from big endian byte array to little endian word array. */
	for (i = 0, ptr = inout + key->len - 1; i < key->len; i++, ptr--)
		val[i] = get_unaligned_be32(ptr);

	if (0 != num_public_exponent_bits(key, &k))
		return -EINVAL;

	if (k < 2) {
		debug("Public exponent is too short (%d bits, minimum 2)\n",
		      k);
		return -EINVAL;
	}

	if (!is_public_exponent_bit_set(key, 0)) {
		debug("LSB of RSA public exponent must be set.\n");
		return -EINVAL;
	}

	/* the bit at e[k-1] is 1 by definition, so start with: C := M */
	montgomery_mul(key, acc, val, key->rr); /* acc = a * RR / R mod n */
	/* retain scaled version for intermediate use */
	memcpy(a_scaled, acc, key->len * sizeof(a_scaled[0]));

	for (j = k - 2; j > 0; --j) {
		montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */

		if (is_public_exponent_bit_set(key, j)) {
			/* acc = tmp * val / R mod n */
			montgomery_mul(key, acc, tmp, a_scaled);
		} else {
			/* e[j] == 0, copy tmp back to acc for next operation */
			memcpy(acc, tmp, key->len * sizeof(acc[0]));
		}
	}

	/* the bit at e[0] is always 1 */
	montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
	montgomery_mul(key, acc, tmp, val); /* acc = tmp * a / R mod M */
	memcpy(result, acc, key->len * sizeof(result[0]));

	/* Make sure result < mod; result is at most 1x mod too large. */
	if (greater_equal_modulus(key, result))
		subtract_modulus(key, result);

	/* Convert to bigendian byte array */
	for (i = key->len - 1, ptr = inout; (int)i >= 0; i--, ptr++)
		put_unaligned_be32(result[i], ptr);
	return 0;
}

static int rsa_verify_key(const struct rsa_public_key *key, const uint8_t *sig,
			  const uint32_t sig_len, const uint8_t *hash,
			  struct checksum_algo *algo)
{
	const uint8_t *padding;
	int pad_len;
	int ret;

	if (!key || !sig || !hash || !algo)
		return -EIO;

	if (sig_len != (key->len * sizeof(uint32_t))) {
		debug("Signature is of incorrect length %d\n", sig_len);
		return -EINVAL;
	}

	debug("Checksum algorithm: %s", algo->name);

	/* Sanity check for stack size */
	if (sig_len > RSA_MAX_SIG_BITS / 8) {
		debug("Signature length %u exceeds maximum %d\n", sig_len,
		      RSA_MAX_SIG_BITS / 8);
		return -EINVAL;
	}

	uint32_t buf[sig_len / sizeof(uint32_t)];

	memcpy(buf, sig, sig_len);

	ret = pow_mod(key, buf);
	if (ret)
		return ret;

	padding = algo->rsa_padding;
	pad_len = algo->pad_len - algo->checksum_len;

	/* Check pkcs1.5 padding bytes. */
	if (memcmp(buf, padding, pad_len)) {
		debug("In RSAVerify(): Padding check failed!\n");
		return -EINVAL;
	}

	/* Check hash. */
	if (memcmp((uint8_t *)buf + pad_len, hash, sig_len - pad_len)) {
		debug("In RSAVerify(): Hash check failed!\n");
		return -EACCES;
	}

	return 0;
}

static void rsa_convert_big_endian(uint32_t *dst, const uint32_t *src, int len)
{
	int i;

	for (i = 0; i < len; i++)
		dst[i] = fdt32_to_cpu(src[len - 1 - i]);
}

static int rsa_verify_with_keynode(struct image_sign_info *info,
		const void *hash, uint8_t *sig, uint sig_len, int node)
{
	const void *blob = info->fdt_blob;
	struct rsa_public_key key;
	const void *modulus, *rr;
	const uint64_t *public_exponent;
	int length;
	int ret;

	if (node < 0) {
		debug("%s: Skipping invalid node", __func__);
		return -EBADF;
	}
	if (!fdt_getprop(blob, node, "rsa,n0-inverse", NULL)) {
		debug("%s: Missing rsa,n0-inverse", __func__);
		return -EFAULT;
	}
	key.len = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
	key.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
	public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
	if (!public_exponent || length < sizeof(*public_exponent))
		key.exponent = RSA_DEFAULT_PUBEXP;
	else
		key.exponent = fdt64_to_cpu(*public_exponent);
	modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
	rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
	if (!key.len || !modulus || !rr) {
		debug("%s: Missing RSA key info", __func__);
		return -EFAULT;
	}

	/* Sanity check for stack size */
	if (key.len > RSA_MAX_KEY_BITS || key.len < RSA_MIN_KEY_BITS) {
		debug("RSA key bits %u outside allowed range %d..%d\n",
		      key.len, RSA_MIN_KEY_BITS, RSA_MAX_KEY_BITS);
		return -EFAULT;
	}
	key.len /= sizeof(uint32_t) * 8;
	uint32_t key1[key.len], key2[key.len];

	key.modulus = key1;
	key.rr = key2;
	rsa_convert_big_endian(key.modulus, modulus, key.len);
	rsa_convert_big_endian(key.rr, rr, key.len);
	if (!key.modulus || !key.rr) {
		debug("%s: Out of memory", __func__);
		return -ENOMEM;
	}

	debug("key length %d\n", key.len);
	ret = rsa_verify_key(&key, sig, sig_len, hash, info->algo->checksum);
	if (ret) {
		printf("%s: RSA failed to verify: %d\n", __func__, ret);
		return ret;
	}

	return 0;
}

int rsa_verify(struct image_sign_info *info,
	       const struct image_region region[], int region_count,
	       uint8_t *sig, uint sig_len)
{
	const void *blob = info->fdt_blob;
	/* Reserve memory for maximum checksum-length */
	uint8_t hash[info->algo->checksum->pad_len];
	int ndepth, noffset;
	int sig_node, node;
	char name[100];
	int ret;

	/*
	 * Verify that the checksum-length does not exceed the
	 * rsa-signature-length
	 */
	if (info->algo->checksum->checksum_len >
	    info->algo->checksum->pad_len) {
		debug("%s: invlaid checksum-algorithm %s for %s\n",
		      __func__, info->algo->checksum->name, info->algo->name);
		return -EINVAL;
	}

	sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
	if (sig_node < 0) {
		debug("%s: No signature node found\n", __func__);
		return -ENOENT;
	}

	/* Calculate checksum with checksum-algorithm */
	info->algo->checksum->calculate(region, region_count, hash);

	/* See if we must use a particular key */
	if (info->required_keynode != -1) {
		ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
			info->required_keynode);
		if (!ret)
			return ret;
	}

	/* Look for a key that matches our hint */
	snprintf(name, sizeof(name), "key-%s", info->keyname);
	node = fdt_subnode_offset(blob, sig_node, name);
	ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
	if (!ret)
		return ret;

	/* No luck, so try each of the keys in turn */
	for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node, &ndepth);
			(noffset >= 0) && (ndepth > 0);
			noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
		if (ndepth == 1 && noffset != node) {
			ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
						      noffset);
			if (!ret)
				break;
		}
	}

	return ret;
}
Commit	Line	Data
19c402af SG	1	/*
	2	* Copyright (c) 2013, Google Inc.
	3	*
1a459660	4	* SPDX-License-Identifier: GPL-2.0+
19c402af SG	5	*/
19c402af SG	6
29a23f9d	7	#ifndef USE_HOSTCC
19c402af SG	8	#include <common.h>
19c402af SG	9	#include <fdtdec.h>
29a23f9d	10	#include <asm/types.h>
19c402af SG	11	#include <asm/byteorder.h>
19c402af SG	12	#include <asm/errno.h>
29a23f9d	13	#include <asm/types.h>
19c402af	14	#include <asm/unaligned.h>
29a23f9d HS	15	#else
	16	#include "fdt_host.h"
	17	#include "mkimage.h"
	18	#include <fdt_support.h>
	19	#endif
2b9912e6 JH	20	#include <u-boot/rsa.h>
	21	#include <u-boot/sha1.h>
	22	#include <u-boot/sha256.h>
19c402af	23
19c402af SG	24	#define UINT64_MULT32(v, multby) (((uint64_t)(v)) * ((uint32_t)(multby)))
19c402af SG	25
29a23f9d HS	26	#define get_unaligned_be32(a) fdt32_to_cpu((uint32_t )a)
	27	#define put_unaligned_be32(a, b) ((uint32_t )(b) = cpu_to_fdt32(a))
	28
e0f2f155 MW	29	/* Default public exponent for backward compatibility */
	30	#define RSA_DEFAULT_PUBEXP 65537
	31
19c402af SG	32	/**
	33	* subtract_modulus() - subtract modulus from the given value
	34	*
	35	* @key: Key containing modulus to subtract
	36	* @num: Number to subtract modulus from, as little endian word array
	37	*/
	38	static void subtract_modulus(const struct rsa_public_key *key, uint32_t num[])
	39	{
	40	int64_t acc = 0;
	41	uint i;
	42
	43	for (i = 0; i < key->len; i++) {
	44	acc += (uint64_t)num[i] - key->modulus[i];
	45	num[i] = (uint32_t)acc;
	46	acc >>= 32;
	47	}
	48	}
	49
	50	/**
	51	* greater_equal_modulus() - check if a value is >= modulus
	52	*
	53	* @key: Key containing modulus to check
	54	* @num: Number to check against modulus, as little endian word array
	55	* @return 0 if num < modulus, 1 if num >= modulus
	56	*/
	57	static int greater_equal_modulus(const struct rsa_public_key *key,
	58	uint32_t num[])
	59	{
	60	uint32_t i;
	61
	62	for (i = key->len - 1; i >= 0; i--) {
	63	if (num[i] < key->modulus[i])
	64	return 0;
	65	if (num[i] > key->modulus[i])
	66	return 1;
	67	}
	68
	69	return 1; /* equal */
	70	}
	71
	72	/**
	73	* montgomery_mul_add_step() - Perform montgomery multiply-add step
	74	*
	75	* Operation: montgomery result[] += a * b[] / n0inv % modulus
	76	*
	77	* @key: RSA key
	78	* @result: Place to put result, as little endian word array
	79	* @a: Multiplier
	80	* @b: Multiplicand, as little endian word array
	81	*/
	82	static void montgomery_mul_add_step(const struct rsa_public_key *key,
	83	uint32_t result[], const uint32_t a, const uint32_t b[])
	84	{
	85	uint64_t acc_a, acc_b;
	86	uint32_t d0;
	87	uint i;
	88
	89	acc_a = (uint64_t)a * b[0] + result[0];
	90	d0 = (uint32_t)acc_a * key->n0inv;
	91	acc_b = (uint64_t)d0 * key->modulus[0] + (uint32_t)acc_a;
	92	for (i = 1; i < key->len; i++) {
	93	acc_a = (acc_a >> 32) + (uint64_t)a * b[i] + result[i];
	94	acc_b = (acc_b >> 32) + (uint64_t)d0 * key->modulus[i] +
	95	(uint32_t)acc_a;
96	result[i - 1] = (uint32_t)acc_b;
97	}
98
99	acc_a = (acc_a >> 32) + (acc_b >> 32);
100
101	result[i - 1] = (uint32_t)acc_a;
102
103	if (acc_a >> 32)
104	subtract_modulus(key, result);
105	}
106
107	/**
108	* montgomery_mul() - Perform montgomery mutitply
109	*
110	* Operation: montgomery result[] = a[] * b[] / n0inv % modulus
111	*
112	* @key: RSA key
113	* @result: Place to put result, as little endian word array
114	* @a: Multiplier, as little endian word array
115	* @b: Multiplicand, as little endian word array
116	*/
117	static void montgomery_mul(const struct rsa_public_key *key,
118	uint32_t result[], uint32_t a[], const uint32_t b[])
119	{
120	uint i;
121
122	for (i = 0; i < key->len; ++i)
123	result[i] = 0;
124	for (i = 0; i < key->len; ++i)
125	montgomery_mul_add_step(key, result, a[i], b);
126	}
127
e0f2f155 MW	128	/**
	129	* num_pub_exponent_bits() - Number of bits in the public exponent
	130	*
	131	* @key: RSA key
	132	* @num_bits: Storage for the number of public exponent bits
	133	*/
	134	static int num_public_exponent_bits(const struct rsa_public_key *key,
	135	int *num_bits)
	136	{
	137	uint64_t exponent;
	138	int exponent_bits;
	139	const uint max_bits = (sizeof(exponent) * 8);
	140
	141	exponent = key->exponent;
	142	exponent_bits = 0;
	143
	144	if (!exponent) {
	145	*num_bits = exponent_bits;
	146	return 0;
	147	}
	148
	149	for (exponent_bits = 1; exponent_bits < max_bits + 1; ++exponent_bits)
	150	if (!(exponent >>= 1)) {
	151	*num_bits = exponent_bits;
	152	return 0;
	153	}
	154
	155	return -EINVAL;
	156	}
	157
	158	/**
	159	* is_public_exponent_bit_set() - Check if a bit in the public exponent is set
	160	*
	161	* @key: RSA key
	162	* @pos: The bit position to check
	163	*/
	164	static int is_public_exponent_bit_set(const struct rsa_public_key *key,
	165	int pos)
	166	{
	167	return key->exponent & (1ULL << pos);
	168	}
	169
19c402af SG	170	/**
	171	* pow_mod() - in-place public exponentiation
	172	*
	173	* @key: RSA key
	174	* @inout: Big-endian word array containing value and result
	175	*/
	176	static int pow_mod(const struct rsa_public_key key, uint32_t inout)
	177	{
	178	uint32_t result, ptr;
	179	uint i;
e0f2f155	180	int j, k;
19c402af SG	181
	182	/* Sanity check for stack size - key->len is in 32-bit words */
	183	if (key->len > RSA_MAX_KEY_BITS / 32) {
	184	debug("RSA key words %u exceeds maximum %d\n", key->len,
	185	RSA_MAX_KEY_BITS / 32);
	186	return -EINVAL;
	187	}
	188
	189	uint32_t val[key->len], acc[key->len], tmp[key->len];
e0f2f155	190	uint32_t a_scaled[key->len];
19c402af SG	191	result = tmp; /* Re-use location. */
	192
	193	/* Convert from big endian byte array to little endian word array. */
	194	for (i = 0, ptr = inout + key->len - 1; i < key->len; i++, ptr--)
	195	val[i] = get_unaligned_be32(ptr);
	196
e0f2f155 MW	197	if (0 != num_public_exponent_bits(key, &k))
	198	return -EINVAL;
	199
	200	if (k < 2) {
	201	debug("Public exponent is too short (%d bits, minimum 2)\n",
	202	k);
	203	return -EINVAL;
	204	}
	205
	206	if (!is_public_exponent_bit_set(key, 0)) {
	207	debug("LSB of RSA public exponent must be set.\n");
	208	return -EINVAL;
19c402af	209	}
e0f2f155 MW	210
	211	/* the bit at e[k-1] is 1 by definition, so start with: C := M */
	212	montgomery_mul(key, acc, val, key->rr); /* acc = a * RR / R mod n */
	213	/* retain scaled version for intermediate use */
	214	memcpy(a_scaled, acc, key->len * sizeof(a_scaled[0]));
	215
	216	for (j = k - 2; j > 0; --j) {
	217	montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
	218
	219	if (is_public_exponent_bit_set(key, j)) {
	220	/* acc = tmp * val / R mod n */
	221	montgomery_mul(key, acc, tmp, a_scaled);
	222	} else {
	223	/* e[j] == 0, copy tmp back to acc for next operation */
	224	memcpy(acc, tmp, key->len * sizeof(acc[0]));
	225	}
	226	}
	227
	228	/* the bit at e[0] is always 1 */
	229	montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
	230	montgomery_mul(key, acc, tmp, val); /* acc = tmp * a / R mod M */
	231	memcpy(result, acc, key->len * sizeof(result[0]));
19c402af SG	232
	233	/* Make sure result < mod; result is at most 1x mod too large. */
	234	if (greater_equal_modulus(key, result))
	235	subtract_modulus(key, result);
	236
	237	/* Convert to bigendian byte array */
	238	for (i = key->len - 1, ptr = inout; (int)i >= 0; i--, ptr++)
	239	put_unaligned_be32(result[i], ptr);
19c402af SG	240	return 0;
	241	}
	242
	243	static int rsa_verify_key(const struct rsa_public_key key, const uint8_t sig,
646257d1 HS	244	const uint32_t sig_len, const uint8_t *hash,
646257d1 HS	245	struct checksum_algo *algo)
19c402af SG	246	{
	247	const uint8_t *padding;
	248	int pad_len;
	249	int ret;
	250
646257d1	251	if (!key \|\| !sig \|\| !hash \|\| !algo)
19c402af SG	252	return -EIO;
	253
	254	if (sig_len != (key->len * sizeof(uint32_t))) {
	255	debug("Signature is of incorrect length %d\n", sig_len);
	256	return -EINVAL;
	257	}
	258
646257d1 HS	259	debug("Checksum algorithm: %s", algo->name);
646257d1 HS	260
19c402af SG	261	/* Sanity check for stack size */
	262	if (sig_len > RSA_MAX_SIG_BITS / 8) {
	263	debug("Signature length %u exceeds maximum %d\n", sig_len,
	264	RSA_MAX_SIG_BITS / 8);
	265	return -EINVAL;
	266	}
	267
	268	uint32_t buf[sig_len / sizeof(uint32_t)];
	269
	270	memcpy(buf, sig, sig_len);
	271
	272	ret = pow_mod(key, buf);
	273	if (ret)
	274	return ret;
	275
646257d1	276	padding = algo->rsa_padding;
db1b5f3d	277	pad_len = algo->pad_len - algo->checksum_len;
19c402af SG	278
	279	/* Check pkcs1.5 padding bytes. */
	280	if (memcmp(buf, padding, pad_len)) {
	281	debug("In RSAVerify(): Padding check failed!\n");
	282	return -EINVAL;
	283	}
	284
	285	/* Check hash. */
	286	if (memcmp((uint8_t *)buf + pad_len, hash, sig_len - pad_len)) {
	287	debug("In RSAVerify(): Hash check failed!\n");
	288	return -EACCES;
	289	}
	290
	291	return 0;
	292	}
	293
	294	static void rsa_convert_big_endian(uint32_t dst, const uint32_t src, int len)
	295	{
	296	int i;
	297
	298	for (i = 0; i < len; i++)
	299	dst[i] = fdt32_to_cpu(src[len - 1 - i]);
	300	}
	301
	302	static int rsa_verify_with_keynode(struct image_sign_info *info,
	303	const void hash, uint8_t sig, uint sig_len, int node)
	304	{
	305	const void *blob = info->fdt_blob;
	306	struct rsa_public_key key;
	307	const void modulus, rr;
e0f2f155 MW	308	const uint64_t *public_exponent;
e0f2f155 MW	309	int length;
19c402af SG	310	int ret;
	311
	312	if (node < 0) {
	313	debug("%s: Skipping invalid node", __func__);
	314	return -EBADF;
	315	}
	316	if (!fdt_getprop(blob, node, "rsa,n0-inverse", NULL)) {
	317	debug("%s: Missing rsa,n0-inverse", __func__);
	318	return -EFAULT;
	319	}
	320	key.len = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
	321	key.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
e0f2f155 MW	322	public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
	323	if (!public_exponent \|\| length < sizeof(*public_exponent))
	324	key.exponent = RSA_DEFAULT_PUBEXP;
	325	else
	326	key.exponent = fdt64_to_cpu(*public_exponent);
19c402af SG	327	modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
	328	rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
	329	if (!key.len \|\| !modulus \|\| !rr) {
	330	debug("%s: Missing RSA key info", __func__);
	331	return -EFAULT;
	332	}
	333
	334	/* Sanity check for stack size */
	335	if (key.len > RSA_MAX_KEY_BITS \|\| key.len < RSA_MIN_KEY_BITS) {
	336	debug("RSA key bits %u outside allowed range %d..%d\n",
	337	key.len, RSA_MIN_KEY_BITS, RSA_MAX_KEY_BITS);
	338	return -EFAULT;
	339	}
	340	key.len /= sizeof(uint32_t) * 8;
	341	uint32_t key1[key.len], key2[key.len];
	342
	343	key.modulus = key1;
	344	key.rr = key2;
	345	rsa_convert_big_endian(key.modulus, modulus, key.len);
	346	rsa_convert_big_endian(key.rr, rr, key.len);
	347	if (!key.modulus \|\| !key.rr) {
	348	debug("%s: Out of memory", __func__);
	349	return -ENOMEM;
	350	}
	351
	352	debug("key length %d\n", key.len);
646257d1	353	ret = rsa_verify_key(&key, sig, sig_len, hash, info->algo->checksum);
19c402af SG	354	if (ret) {
	355	printf("%s: RSA failed to verify: %d\n", __func__, ret);
	356	return ret;
	357	}
	358
	359	return 0;
	360	}
	361
	362	int rsa_verify(struct image_sign_info *info,
	363	const struct image_region region[], int region_count,
	364	uint8_t *sig, uint sig_len)
	365	{
	366	const void *blob = info->fdt_blob;
646257d1	367	/* Reserve memory for maximum checksum-length */
db1b5f3d	368	uint8_t hash[info->algo->checksum->pad_len];
19c402af SG	369	int ndepth, noffset;
	370	int sig_node, node;
	371	char name[100];
646257d1 HS	372	int ret;
	373
	374	/*
	375	* Verify that the checksum-length does not exceed the
	376	* rsa-signature-length
	377	*/
db1b5f3d HS	378	if (info->algo->checksum->checksum_len >
	379	info->algo->checksum->pad_len) {
	380	debug("%s: invlaid checksum-algorithm %s for %s\n",
	381	__func__, info->algo->checksum->name, info->algo->name);
646257d1 HS	382	return -EINVAL;
646257d1 HS	383	}
19c402af SG	384
	385	sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
	386	if (sig_node < 0) {
	387	debug("%s: No signature node found\n", __func__);
	388	return -ENOENT;
	389	}
	390
646257d1 HS	391	/* Calculate checksum with checksum-algorithm */
646257d1 HS	392	info->algo->checksum->calculate(region, region_count, hash);
19c402af SG	393
	394	/* See if we must use a particular key */
	395	if (info->required_keynode != -1) {
	396	ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
	397	info->required_keynode);
	398	if (!ret)
	399	return ret;
	400	}
	401
	402	/* Look for a key that matches our hint */
	403	snprintf(name, sizeof(name), "key-%s", info->keyname);
	404	node = fdt_subnode_offset(blob, sig_node, name);
	405	ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
	406	if (!ret)
	407	return ret;
	408
	409	/* No luck, so try each of the keys in turn */
	410	for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node, &ndepth);
	411	(noffset >= 0) && (ndepth > 0);
	412	noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
	413	if (ndepth == 1 && noffset != node) {
	414	ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
	415	noffset);
	416	if (!ret)
	417	break;
	418	}
	419	}
	420
	421	return ret;
	422	}