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rsa: add support of padding pss

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We add the support of the padding pss for rsa signature.
This new padding is often recommended instead of pkcs-1.5.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Philippe Reynes 2018-11-14 13:51:01 +01:00 committed by Tom Rini
parent 20031567e1
commit 061daa0b61
6 changed files with 230 additions and 0 deletions
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8
Kconfig
View file

@ -290,6 +290,14 @@ config FIT_SIGNATURE_MAX_SIZE
device memory. Assure this size does not extend past expected storage
space.
config FIT_ENABLE_RSASSA_PSS_SUPPORT
bool "Support rsassa-pss signature scheme of FIT image contents"
depends on FIT_SIGNATURE
default n
help
Enable this to support the pss padding algorithm as described
in the rfc8017 (https://tools.ietf.org/html/rfc8017).
config FIT_VERBOSE
bool "Show verbose messages when FIT images fail"
help

6
common/image-sig.c
View file

@ -76,6 +76,12 @@ struct padding_algo padding_algos[] = {
.name = "pkcs-1.5",
.verify = padding_pkcs_15_verify,
},
#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
{
.name = "pss",
.verify = padding_pss_verify,
}
#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
};
struct checksum_algo *image_get_checksum_algo(const char *full_name)

1
include/image.h
View file

@ -30,6 +30,7 @@ struct fdt_region;
#define IMAGE_ENABLE_FIT 1
#define IMAGE_ENABLE_OF_LIBFDT 1
#define CONFIG_FIT_VERBOSE 1 /* enable fit_format_{error,warning}() */
#define CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT 1
#define CONFIG_FIT_ENABLE_SHA256_SUPPORT
#define CONFIG_SHA1
#define CONFIG_SHA256

15
include/u-boot/rsa.h
View file

@ -101,6 +101,12 @@ int rsa_verify(struct image_sign_info *info,
int padding_pkcs_15_verify(struct image_sign_info *info,
uint8_t *msg, int msg_len,
const uint8_t *hash, int hash_len);
#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
int padding_pss_verify(struct image_sign_info *info,
uint8_t *msg, int msg_len,
const uint8_t *hash, int hash_len);
#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
#else
static inline int rsa_verify(struct image_sign_info *info,
const struct image_region region[], int region_count,
@ -115,6 +121,15 @@ static inline int padding_pkcs_15_verify(struct image_sign_info *info,
{
return -ENXIO;
}
#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
static inline int padding_pss_verify(struct image_sign_info *info,
uint8_t *msg, int msg_len,
const uint8_t *hash, int hash_len)
{
return -ENXIO;
}
#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
#endif
#define RSA_DEFAULT_PADDING_NAME "pkcs-1.5"

10
lib/rsa/rsa-sign.c
View file

@ -438,6 +438,16 @@ static int rsa_sign_with_key(RSA *rsa, struct padding_algo *padding_algo,
goto err_sign;
}
#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
if (padding_algo && !strcmp(padding_algo->name, "pss")) {
if (EVP_PKEY_CTX_set_rsa_padding(ckey,
RSA_PKCS1_PSS_PADDING) <= 0) {
ret = rsa_err("Signer padding setup failed");
goto err_sign;
}
}
#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
for (i = 0; i < region_count; i++) {
if (!EVP_DigestSignUpdate(context, region[i].data,
region[i].size)) {

190
lib/rsa/rsa-verify.c
View file

@ -80,6 +80,196 @@ int padding_pkcs_15_verify(struct image_sign_info *info,
return 0;
}
#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
static void u32_i2osp(uint32_t val, uint8_t *buf)
{
buf[0] = (uint8_t)((val >> 24) & 0xff);
buf[1] = (uint8_t)((val >> 16) & 0xff);
buf[2] = (uint8_t)((val >> 8) & 0xff);
buf[3] = (uint8_t)((val >> 0) & 0xff);
}
/**
* mask_generation_function1() - generate an octet string
*
* Generate an octet string used to check rsa signature.
* It use an input octet string and a hash function.
*
* @checksum: A Hash function
* @seed: Specifies an input variable octet string
* @seed_len: Size of the input octet string
* @output: Specifies the output octet string
* @output_len: Size of the output octet string
* @return 0 if the octet string was correctly generated, others on error
*/
static int mask_generation_function1(struct checksum_algo *checksum,
uint8_t *seed, int seed_len,
uint8_t *output, int output_len)
{
struct image_region region[2];
int ret = 0, i, i_output = 0, region_count = 2;
uint32_t counter = 0;
uint8_t buf_counter[4], *tmp;
int hash_len = checksum->checksum_len;
memset(output, 0, output_len);
region[0].data = seed;
region[0].size = seed_len;
region[1].data = &buf_counter[0];
region[1].size = 4;
tmp = malloc(hash_len);
if (!tmp) {
debug("%s: can't allocate array tmp\n", __func__);
ret = -ENOMEM;
goto out;
}
while (i_output < output_len) {
u32_i2osp(counter, &buf_counter[0]);
ret = checksum->calculate(checksum->name,
region, region_count,
tmp);
if (ret < 0) {
debug("%s: Error in checksum calculation\n", __func__);
goto out;
}
i = 0;
while ((i_output < output_len) && (i < hash_len)) {
output[i_output] = tmp[i];
i_output++;
i++;
}
counter++;
}
out:
free(tmp);
return ret;
}
static int compute_hash_prime(struct checksum_algo *checksum,
uint8_t *pad, int pad_len,
uint8_t *hash, int hash_len,
uint8_t *salt, int salt_len,
uint8_t *hprime)
{
struct image_region region[3];
int ret, region_count = 3;
region[0].data = pad;
region[0].size = pad_len;
region[1].data = hash;
region[1].size = hash_len;
region[2].data = salt;
region[2].size = salt_len;
ret = checksum->calculate(checksum->name, region, region_count, hprime);
if (ret < 0) {
debug("%s: Error in checksum calculation\n", __func__);
goto out;
}
out:
return ret;
}
int padding_pss_verify(struct image_sign_info *info,
uint8_t *msg, int msg_len,
const uint8_t *hash, int hash_len)
{
uint8_t *masked_db = NULL;
int masked_db_len = msg_len - hash_len - 1;
uint8_t *h = NULL, *hprime = NULL;
int h_len = hash_len;
uint8_t *db_mask = NULL;
int db_mask_len = masked_db_len;
uint8_t *db = NULL, *salt = NULL;
int db_len = masked_db_len, salt_len = msg_len - hash_len - 2;
uint8_t pad_zero[8] = { 0 };
int ret, i, leftmost_bits = 1;
uint8_t leftmost_mask;
struct checksum_algo *checksum = info->checksum;
/* first, allocate everything */
masked_db = malloc(masked_db_len);
h = malloc(h_len);
db_mask = malloc(db_mask_len);
db = malloc(db_len);
salt = malloc(salt_len);
hprime = malloc(hash_len);
if (!masked_db || !h || !db_mask || !db || !salt || !hprime) {
printf("%s: can't allocate some buffer\n", __func__);
ret = -ENOMEM;
goto out;
}
/* step 4: check if the last byte is 0xbc */
if (msg[msg_len - 1] != 0xbc) {
printf("%s: invalid pss padding (0xbc is missing)\n", __func__);
ret = -EINVAL;
goto out;
}
/* step 5 */
memcpy(masked_db, msg, masked_db_len);
memcpy(h, msg + masked_db_len, h_len);
/* step 6 */
leftmost_mask = (0xff >> (8 - leftmost_bits)) << (8 - leftmost_bits);
if (masked_db[0] & leftmost_mask) {
printf("%s: invalid pss padding ", __func__);
printf("(leftmost bit of maskedDB not zero)\n");
ret = -EINVAL;
goto out;
}
/* step 7 */
mask_generation_function1(checksum, h, h_len, db_mask, db_mask_len);
/* step 8 */
for (i = 0; i < db_len; i++)
db[i] = masked_db[i] ^ db_mask[i];
/* step 9 */
db[0] &= 0xff >> leftmost_bits;
/* step 10 */
if (db[0] != 0x01) {
printf("%s: invalid pss padding ", __func__);
printf("(leftmost byte of db isn't 0x01)\n");
ret = EINVAL;
goto out;
}
/* step 11 */
memcpy(salt, &db[1], salt_len);
/* step 12 & 13 */
compute_hash_prime(checksum, pad_zero, 8,
(uint8_t *)hash, hash_len,
salt, salt_len, hprime);
/* step 14 */
ret = memcmp(h, hprime, hash_len);
out:
free(hprime);
free(salt);
free(db);
free(db_mask);
free(h);
free(masked_db);
return ret;
}
#endif
/**
* rsa_verify_key() - Verify a signature against some data using RSA Key
*