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lib: rsa: function to verify a signature against a hash

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rsa_verify() expects a memory region and wants to do the hashing itself,
but there may be cases where the hashing is done via other means,
like hashing a squashfs rootfs.

So add rsa_verify_hash() to allow verifiying a signature against
an existing hash. As this entails the same verification routines
we can just move the relevant code over from rsa_verify() and also
call rsa_verify_hash() from there.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
This commit is contained in:
Heiko Stuebner 2020-05-22 16:20:33 +02:00 committed by Tom Rini
parent bdded2015c
commit c89b41b4db
2 changed files with 53 additions and 24 deletions
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21
include/u-boot/rsa.h
View File

@ -82,6 +82,20 @@ static inline int rsa_add_verify_data(struct image_sign_info *info,
#endif
#if IMAGE_ENABLE_VERIFY
/**
* rsa_verify_hash() - Verify a signature against a hash
*
* Verify a RSA PKCS1.5 signature against an expected hash.
*
* @info: Specifies key and FIT information
* @hash: Hash according to algorithm specified in @info
* @sig: Signature
* @sig_len: Number of bytes in signature
* @return 0 if verified, -ve on error
*/
int rsa_verify_hash(struct image_sign_info *info,
const uint8_t *hash, uint8_t *sig, uint sig_len);
/**
* rsa_verify() - Verify a signature against some data
*
@ -108,6 +122,13 @@ int padding_pss_verify(struct image_sign_info *info,
const uint8_t *hash, int hash_len);
#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
#else
static inline int rsa_verify_hash(struct image_sign_info *info,
const uint8_t *hash,
uint8_t *sig, uint sig_len)
{
return -ENXIO;
}
static inline int rsa_verify(struct image_sign_info *info,
const struct image_region region[], int region_count,
uint8_t *sig, uint sig_len)

56
lib/rsa/rsa-verify.c
View File

@ -478,33 +478,11 @@ static int rsa_verify_with_keynode(struct image_sign_info *info,
}
#endif
int rsa_verify(struct image_sign_info *info,
const struct image_region region[], int region_count,
uint8_t *sig, uint sig_len)
int rsa_verify_hash(struct image_sign_info *info,
const uint8_t *hash, uint8_t *sig, uint sig_len)
{
/* Reserve memory for maximum checksum-length */
uint8_t hash[info->crypto->key_len];
int ret = -EACCES;
/*
* Verify that the checksum-length does not exceed the
* rsa-signature-length
*/
if (info->checksum->checksum_len >
info->crypto->key_len) {
debug("%s: invlaid checksum-algorithm %s for %s\n",
__func__, info->checksum->name, info->crypto->name);
return -EINVAL;
}
/* Calculate checksum with checksum-algorithm */
ret = info->checksum->calculate(info->checksum->name,
region, region_count, hash);
if (ret < 0) {
debug("%s: Error in checksum calculation\n", __func__);
return -EINVAL;
}
if (CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) && !info->fdt_blob) {
/* don't rely on fdt properties */
ret = rsa_verify_with_pkey(info, hash, sig, sig_len);
@ -555,3 +533,33 @@ int rsa_verify(struct image_sign_info *info,
return ret;
}
int rsa_verify(struct image_sign_info *info,
const struct image_region region[], int region_count,
uint8_t *sig, uint sig_len)
{
/* Reserve memory for maximum checksum-length */
uint8_t hash[info->crypto->key_len];
int ret = -EACCES;
/*
* Verify that the checksum-length does not exceed the
* rsa-signature-length
*/
if (info->checksum->checksum_len >
info->crypto->key_len) {
debug("%s: invlaid checksum-algorithm %s for %s\n",
__func__, info->checksum->name, info->crypto->name);
return -EINVAL;
}
/* Calculate checksum with checksum-algorithm */
ret = info->checksum->calculate(info->checksum->name,
region, region_count, hash);
if (ret < 0) {
debug("%s: Error in checksum calculation\n", __func__);
return -EINVAL;
}
return rsa_verify_hash(info, hash, sig, sig_len);
}