On Mon, Feb 07, 2022 at 09:24:48PM -0800, Eric Biggers wrote:
From: Eric Biggers ebiggers@google.com
It is insecure to allow arbitrary hash algorithms and signature encodings to be used with arbitrary signature algorithms. Notably, ECDSA, ECRDSA, and SM2 all sign/verify raw hash values and don't disambiguate between different hash algorithms like RSA PKCS#1 v1.5 padding does. Therefore, they need to be restricted to certain sets of hash algorithms (ideally just one, but in practice small sets are used). Additionally, the encoding is an integral part of modern signature algorithms, and is not supposed to vary.
Therefore, tighten the checks of hash_algo and encoding done by software_key_determine_akcipher().
Also rearrange the parameters to software_key_determine_akcipher() to put the public_key first, as this is the most important parameter and it often determines everything else.
Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification") Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm") Cc: stable@vger.kernel.org Tested-by: Stefan Berger stefanb@linux.ibm.com Tested-by: Tianjia Zhang tianjia.zhang@linux.alibaba.com Signed-off-by: Eric Biggers ebiggers@google.com
Reviewed-by: Vitaly Chikunov vt@altlinux.org
Small question below.
crypto/asymmetric_keys/public_key.c | 111 +++++++++++++++++++--------- 1 file changed, 76 insertions(+), 35 deletions(-)
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index e36213945686..7c9e6be35c30 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -60,39 +60,83 @@ static void public_key_destroy(void *payload0, void *payload3) } /*
- Determine the crypto algorithm name.
- Given a public_key, and an encoding and hash_algo to be used for signing
- and/or verification with that key, determine the name of the corresponding
*/
- akcipher algorithm. Also check that encoding and hash_algo are allowed.
-static -int software_key_determine_akcipher(const char *encoding,
const char *hash_algo,const struct public_key *pkey,char alg_name[CRYPTO_MAX_ALG_NAME])+static int +software_key_determine_akcipher(const struct public_key *pkey,
const char *encoding, const char *hash_algo,char alg_name[CRYPTO_MAX_ALG_NAME]){ int n;
- if (strcmp(encoding, "pkcs1") == 0) {
/* The data wangled by the RSA algorithm is typically padded* and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447* sec 8.2].
- if (!encoding)
return -EINVAL;- if (strcmp(pkey->pkey_algo, "rsa") == 0) {
/** RSA signatures usually use EMSA-PKCS1-1_5 [RFC3447 sec 8.2].*/if (strcmp(encoding, "pkcs1") == 0) {if (!hash_algo)n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,"pkcs1pad(%s)",pkey->pkey_algo);elsen = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,"pkcs1pad(%s,%s)",pkey->pkey_algo, hash_algo);return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;}if (strcmp(encoding, "raw") != 0)return -EINVAL;
Should raw RSA be allowed at all? I understand it was there before, but I wonder what is the use case.
Thanks,
/** Raw RSA cannot differentiate between different hash* algorithms.*/if (hash_algo)return -EINVAL;- } else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
if (strcmp(encoding, "x962") != 0)return -EINVAL;/** ECDSA signatures are taken over a raw hash, so they don't* differentiate between different hash algorithms. That means* that the verifier should hard-code a specific hash algorithm.* Unfortunately, in practice ECDSA is used with multiple SHAs,* so we have to allow all of them and not just one.
n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,"pkcs1pad(%s)",pkey->pkey_algo);elsen = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,"pkcs1pad(%s,%s)",pkey->pkey_algo, hash_algo);return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;- }
- if (strcmp(encoding, "raw") == 0 ||
strcmp(encoding, "x962") == 0) {strcpy(alg_name, pkey->pkey_algo);return 0;
return -EINVAL;if (strcmp(hash_algo, "sha1") != 0 &&strcmp(hash_algo, "sha224") != 0 &&strcmp(hash_algo, "sha256") != 0 &&strcmp(hash_algo, "sha384") != 0 &&strcmp(hash_algo, "sha512") != 0)return -EINVAL;- } else if (strcmp(pkey->pkey_algo, "sm2") == 0) {
if (strcmp(encoding, "raw") != 0)return -EINVAL;if (!hash_algo)return -EINVAL;if (strcmp(hash_algo, "sm3") != 0)return -EINVAL;- } else if (strcmp(pkey->pkey_algo, "ecrdsa") == 0) {
if (strcmp(encoding, "raw") != 0)return -EINVAL;if (!hash_algo)return -EINVAL;if (strcmp(hash_algo, "streebog256") != 0 &&strcmp(hash_algo, "streebog512") != 0)return -EINVAL;- } else {
/* Unknown public key algorithm */return -ENOPKG;
- return -ENOPKG;
- if (strscpy(alg_name, pkey->pkey_algo, CRYPTO_MAX_ALG_NAME) < 0)
return -EINVAL;- return 0;
} static u8 *pkey_pack_u32(u8 *dst, u32 val) @@ -113,9 +157,8 @@ static int software_key_query(const struct kernel_pkey_params *params, u8 *key, *ptr; int ret, len;
- ret = software_key_determine_akcipher(params->encoding,
params->hash_algo,pkey, alg_name);
- ret = software_key_determine_akcipher(pkey, params->encoding,
params->hash_algo, alg_name);@@ -179,9 +222,8 @@ static int software_key_eds_op(struct kernel_pkey_params *params, pr_devel("==>%s()\n", __func__);
- ret = software_key_determine_akcipher(params->encoding,
params->hash_algo,pkey, alg_name);
- ret = software_key_determine_akcipher(pkey, params->encoding,
params->hash_algo, alg_name);@@ -340,9 +382,8 @@ int public_key_verify_signature(const struct public_key *pkey, return -EKEYREJECTED; }
- ret = software_key_determine_akcipher(sig->encoding,
sig->hash_algo,pkey, alg_name);
- ret = software_key_determine_akcipher(pkey, sig->encoding,
sig->hash_algo, alg_name);2.35.1