Taken from U-Boot and adopted to barebox with little changes. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
423 lines
11 KiB
C
423 lines
11 KiB
C
/*
|
|
* Copyright (c) 2013, Google Inc.
|
|
*
|
|
* This code is ported from U-Boot code.
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0+
|
|
*/
|
|
|
|
#include <common.h>
|
|
#include <malloc.h>
|
|
#include <of.h>
|
|
#include <digest.h>
|
|
#include <asm/types.h>
|
|
#include <asm/byteorder.h>
|
|
#include <errno.h>
|
|
#include <rsa.h>
|
|
#include <asm/types.h>
|
|
#include <asm/unaligned.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
|
|
|
|
/* This is the minimum/maximum key size we support, in bits */
|
|
#define RSA_MIN_KEY_BITS 1024
|
|
#define RSA_MAX_KEY_BITS 4096
|
|
|
|
/**
|
|
* 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[])
|
|
{
|
|
int i;
|
|
|
|
for (i = (int)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, void *__inout)
|
|
{
|
|
uint32_t *inout = __inout;
|
|
uint32_t *result, *ptr;
|
|
uint i;
|
|
int j, k;
|
|
uint32_t val[RSA_MAX_KEY_BITS / 32], acc[RSA_MAX_KEY_BITS / 32], tmp[RSA_MAX_KEY_BITS / 32];
|
|
uint32_t a_scaled[RSA_MAX_KEY_BITS / 32];
|
|
|
|
/* 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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
|
|
*/
|
|
static const u8 RSA_digest_info_MD5[] = {
|
|
0x30, 0x20, 0x30, 0x0C, 0x06, 0x08,
|
|
0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* OID */
|
|
0x05, 0x00, 0x04, 0x10
|
|
};
|
|
|
|
static const u8 RSA_digest_info_SHA1[] = {
|
|
0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
|
|
0x2B, 0x0E, 0x03, 0x02, 0x1A,
|
|
0x05, 0x00, 0x04, 0x14
|
|
};
|
|
|
|
static const u8 RSA_digest_info_RIPE_MD_160[] = {
|
|
0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
|
|
0x2B, 0x24, 0x03, 0x02, 0x01,
|
|
0x05, 0x00, 0x04, 0x14
|
|
};
|
|
|
|
static const u8 RSA_digest_info_SHA224[] = {
|
|
0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
|
|
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
|
|
0x05, 0x00, 0x04, 0x1C
|
|
};
|
|
|
|
static const u8 RSA_digest_info_SHA256[] = {
|
|
0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
|
|
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
|
|
0x05, 0x00, 0x04, 0x20
|
|
};
|
|
|
|
static const u8 RSA_digest_info_SHA384[] = {
|
|
0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
|
|
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
|
|
0x05, 0x00, 0x04, 0x30
|
|
};
|
|
|
|
static const u8 RSA_digest_info_SHA512[] = {
|
|
0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
|
|
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
|
|
0x05, 0x00, 0x04, 0x40
|
|
};
|
|
|
|
static const struct {
|
|
const u8 *data;
|
|
size_t size;
|
|
} RSA_ASN1_templates[] = {
|
|
#define _(X) { RSA_digest_info_##X, sizeof(RSA_digest_info_##X) }
|
|
[HASH_ALGO_MD5] = _(MD5),
|
|
[HASH_ALGO_SHA1] = _(SHA1),
|
|
[HASH_ALGO_RIPE_MD_160] = _(RIPE_MD_160),
|
|
[HASH_ALGO_SHA256] = _(SHA256),
|
|
[HASH_ALGO_SHA384] = _(SHA384),
|
|
[HASH_ALGO_SHA512] = _(SHA512),
|
|
[HASH_ALGO_SHA224] = _(SHA224),
|
|
#undef _
|
|
};
|
|
|
|
int rsa_verify(const struct rsa_public_key *key, const uint8_t *sig,
|
|
const uint32_t sig_len, const uint8_t *hash,
|
|
enum hash_algo algo)
|
|
{
|
|
int ret = 0;
|
|
uint8_t buf[RSA_MAX_SIG_BITS / 8];
|
|
int i;
|
|
unsigned PS_end, T_offset;
|
|
const u8 *asn1_template = RSA_ASN1_templates[algo].data;
|
|
size_t asn1_size = RSA_ASN1_templates[algo].size;
|
|
struct digest *d = digest_alloc_by_algo(algo);
|
|
|
|
if (!d)
|
|
return -EOPNOTSUPP;
|
|
|
|
if (sig_len != (key->len * sizeof(uint32_t))) {
|
|
debug("Signature is of incorrect length %d, should be %d\n", sig_len,
|
|
key->len * sizeof(uint32_t));
|
|
ret = -EINVAL;
|
|
goto out_free_digest;
|
|
}
|
|
|
|
/* 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);
|
|
ret = -EINVAL;
|
|
goto out_free_digest;
|
|
}
|
|
|
|
memcpy(buf, sig, sig_len);
|
|
|
|
ret = pow_mod(key, buf);
|
|
if (ret)
|
|
goto out_free_digest;
|
|
|
|
T_offset = sig_len - (asn1_size + digest_length(d));
|
|
|
|
PS_end = T_offset - 1;
|
|
if (buf[PS_end] != 0x00) {
|
|
pr_err(" = -EBADMSG [EM[T-1] == %02u]", buf[PS_end]);
|
|
ret = -EBADMSG;
|
|
goto out_free_digest;
|
|
}
|
|
|
|
for (i = 2; i < PS_end; i++) {
|
|
if (buf[i] != 0xff) {
|
|
pr_err(" = -EBADMSG [EM[PS%x] == %02u]", i - 2, buf[i]);
|
|
ret = -EBADMSG;
|
|
goto out_free_digest;
|
|
}
|
|
}
|
|
|
|
if (memcmp(asn1_template, buf + T_offset, asn1_size) != 0) {
|
|
pr_err(" = -EBADMSG [EM[T] ASN.1 mismatch]");
|
|
ret = -EBADMSG;
|
|
goto out_free_digest;
|
|
}
|
|
|
|
if (memcmp(hash, buf + T_offset + asn1_size, digest_length(d)) != 0) {
|
|
pr_err(" = -EKEYREJECTED [EM[T] hash mismatch]");
|
|
ret = -EKEYREJECTED;
|
|
goto out_free_digest;
|
|
}
|
|
|
|
out_free_digest:
|
|
digest_free(d);
|
|
|
|
return ret;
|
|
}
|
|
|
|
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]);
|
|
}
|
|
|
|
int rsa_of_read_key(struct device_node *node, struct rsa_public_key *key)
|
|
{
|
|
const void *modulus, *rr;
|
|
const uint64_t *public_exponent;
|
|
int length;
|
|
|
|
of_property_read_u32(node, "rsa,num-bits", &key->len);
|
|
of_property_read_u32(node, "rsa,n0-inverse", &key->n0inv);
|
|
|
|
public_exponent = of_get_property(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 = of_get_property(node, "rsa,modulus", NULL);
|
|
rr = of_get_property(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;
|
|
|
|
key->modulus = xzalloc(RSA_MAX_KEY_BITS / 8);
|
|
key->rr = xzalloc(RSA_MAX_KEY_BITS / 8);
|
|
|
|
rsa_convert_big_endian(key->modulus, modulus, key->len);
|
|
rsa_convert_big_endian(key->rr, rr, key->len);
|
|
|
|
return 0;
|
|
}
|