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0815291a8f
The signature verification of SM2 needs to add the Za value and
recalculate sig->digest, which requires the detection of the pkey_algo
in public_key_verify_signature(). As Eric Biggers said, the pkey_algo
field in sig is attacker-controlled and should be use pkey->pkey_algo
instead of sig->pkey_algo, and secondly, if sig->pkey_algo is NULL, it
will also cause signature verification failure.
The software_key_determine_akcipher() already forces the algorithms
are matched, so the SM3 algorithm is enforced in the SM2 signature,
although this has been checked, we still avoid using any algorithm
information in the signature as input.
Fixes: 2155256396
("X.509: support OSCCA SM2-with-SM3 certificate verification")
Reported-by: Eric Biggers <ebiggers@google.com>
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
472 lines
12 KiB
C
472 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* In-software asymmetric public-key crypto subtype
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*
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* See Documentation/crypto/asymmetric-keys.rst
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#define pr_fmt(fmt) "PKEY: "fmt
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#include <linux/module.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#include <linux/scatterlist.h>
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#include <linux/asn1.h>
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#include <keys/asymmetric-subtype.h>
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#include <crypto/public_key.h>
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#include <crypto/akcipher.h>
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#include <crypto/sm2.h>
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#include <crypto/sm3_base.h>
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MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
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MODULE_AUTHOR("Red Hat, Inc.");
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MODULE_LICENSE("GPL");
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/*
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* Provide a part of a description of the key for /proc/keys.
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*/
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static void public_key_describe(const struct key *asymmetric_key,
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struct seq_file *m)
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{
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struct public_key *key = asymmetric_key->payload.data[asym_crypto];
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if (key)
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seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
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}
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/*
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* Destroy a public key algorithm key.
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*/
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void public_key_free(struct public_key *key)
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{
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if (key) {
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kfree(key->key);
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kfree(key->params);
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kfree(key);
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}
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}
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EXPORT_SYMBOL_GPL(public_key_free);
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/*
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* Destroy a public key algorithm key.
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*/
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static void public_key_destroy(void *payload0, void *payload3)
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{
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public_key_free(payload0);
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public_key_signature_free(payload3);
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}
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/*
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* Given a public_key, and an encoding and hash_algo to be used for signing
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* and/or verification with that key, determine the name of the corresponding
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* akcipher algorithm. Also check that encoding and hash_algo are allowed.
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*/
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static int
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software_key_determine_akcipher(const struct public_key *pkey,
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const char *encoding, const char *hash_algo,
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char alg_name[CRYPTO_MAX_ALG_NAME])
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{
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int n;
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if (!encoding)
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return -EINVAL;
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if (strcmp(pkey->pkey_algo, "rsa") == 0) {
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/*
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* RSA signatures usually use EMSA-PKCS1-1_5 [RFC3447 sec 8.2].
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*/
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if (strcmp(encoding, "pkcs1") == 0) {
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if (!hash_algo)
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n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
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"pkcs1pad(%s)",
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pkey->pkey_algo);
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else
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n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
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"pkcs1pad(%s,%s)",
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pkey->pkey_algo, hash_algo);
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return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
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}
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if (strcmp(encoding, "raw") != 0)
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return -EINVAL;
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/*
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* Raw RSA cannot differentiate between different hash
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* algorithms.
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*/
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if (hash_algo)
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return -EINVAL;
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} else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
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if (strcmp(encoding, "x962") != 0)
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return -EINVAL;
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/*
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* ECDSA signatures are taken over a raw hash, so they don't
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* differentiate between different hash algorithms. That means
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* that the verifier should hard-code a specific hash algorithm.
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* Unfortunately, in practice ECDSA is used with multiple SHAs,
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* so we have to allow all of them and not just one.
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*/
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if (!hash_algo)
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return -EINVAL;
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if (strcmp(hash_algo, "sha1") != 0 &&
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strcmp(hash_algo, "sha224") != 0 &&
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strcmp(hash_algo, "sha256") != 0 &&
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strcmp(hash_algo, "sha384") != 0 &&
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strcmp(hash_algo, "sha512") != 0)
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return -EINVAL;
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} else if (strcmp(pkey->pkey_algo, "sm2") == 0) {
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if (strcmp(encoding, "raw") != 0)
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return -EINVAL;
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if (!hash_algo)
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return -EINVAL;
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if (strcmp(hash_algo, "sm3") != 0)
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return -EINVAL;
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} else if (strcmp(pkey->pkey_algo, "ecrdsa") == 0) {
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if (strcmp(encoding, "raw") != 0)
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return -EINVAL;
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if (!hash_algo)
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return -EINVAL;
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if (strcmp(hash_algo, "streebog256") != 0 &&
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strcmp(hash_algo, "streebog512") != 0)
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return -EINVAL;
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} else {
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/* Unknown public key algorithm */
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return -ENOPKG;
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}
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if (strscpy(alg_name, pkey->pkey_algo, CRYPTO_MAX_ALG_NAME) < 0)
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return -EINVAL;
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return 0;
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}
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static u8 *pkey_pack_u32(u8 *dst, u32 val)
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{
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memcpy(dst, &val, sizeof(val));
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return dst + sizeof(val);
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}
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/*
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* Query information about a key.
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*/
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static int software_key_query(const struct kernel_pkey_params *params,
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struct kernel_pkey_query *info)
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{
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struct crypto_akcipher *tfm;
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struct public_key *pkey = params->key->payload.data[asym_crypto];
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char alg_name[CRYPTO_MAX_ALG_NAME];
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u8 *key, *ptr;
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int ret, len;
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ret = software_key_determine_akcipher(pkey, params->encoding,
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params->hash_algo, alg_name);
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if (ret < 0)
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return ret;
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tfm = crypto_alloc_akcipher(alg_name, 0, 0);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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ret = -ENOMEM;
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key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
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GFP_KERNEL);
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if (!key)
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goto error_free_tfm;
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memcpy(key, pkey->key, pkey->keylen);
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ptr = key + pkey->keylen;
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ptr = pkey_pack_u32(ptr, pkey->algo);
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ptr = pkey_pack_u32(ptr, pkey->paramlen);
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memcpy(ptr, pkey->params, pkey->paramlen);
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if (pkey->key_is_private)
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ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
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else
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ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
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if (ret < 0)
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goto error_free_key;
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len = crypto_akcipher_maxsize(tfm);
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info->key_size = len * 8;
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info->max_data_size = len;
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info->max_sig_size = len;
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info->max_enc_size = len;
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info->max_dec_size = len;
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info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
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KEYCTL_SUPPORTS_VERIFY);
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if (pkey->key_is_private)
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info->supported_ops |= (KEYCTL_SUPPORTS_DECRYPT |
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KEYCTL_SUPPORTS_SIGN);
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ret = 0;
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error_free_key:
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kfree(key);
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error_free_tfm:
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crypto_free_akcipher(tfm);
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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/*
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* Do encryption, decryption and signing ops.
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*/
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static int software_key_eds_op(struct kernel_pkey_params *params,
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const void *in, void *out)
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{
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const struct public_key *pkey = params->key->payload.data[asym_crypto];
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struct akcipher_request *req;
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struct crypto_akcipher *tfm;
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struct crypto_wait cwait;
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struct scatterlist in_sg, out_sg;
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char alg_name[CRYPTO_MAX_ALG_NAME];
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char *key, *ptr;
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int ret;
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pr_devel("==>%s()\n", __func__);
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ret = software_key_determine_akcipher(pkey, params->encoding,
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params->hash_algo, alg_name);
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if (ret < 0)
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return ret;
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tfm = crypto_alloc_akcipher(alg_name, 0, 0);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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ret = -ENOMEM;
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req = akcipher_request_alloc(tfm, GFP_KERNEL);
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if (!req)
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goto error_free_tfm;
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key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
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GFP_KERNEL);
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if (!key)
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goto error_free_req;
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memcpy(key, pkey->key, pkey->keylen);
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ptr = key + pkey->keylen;
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ptr = pkey_pack_u32(ptr, pkey->algo);
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ptr = pkey_pack_u32(ptr, pkey->paramlen);
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memcpy(ptr, pkey->params, pkey->paramlen);
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if (pkey->key_is_private)
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ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
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else
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ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
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if (ret)
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goto error_free_key;
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sg_init_one(&in_sg, in, params->in_len);
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sg_init_one(&out_sg, out, params->out_len);
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akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
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params->out_len);
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crypto_init_wait(&cwait);
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akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
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CRYPTO_TFM_REQ_MAY_SLEEP,
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crypto_req_done, &cwait);
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/* Perform the encryption calculation. */
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switch (params->op) {
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case kernel_pkey_encrypt:
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ret = crypto_akcipher_encrypt(req);
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break;
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case kernel_pkey_decrypt:
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ret = crypto_akcipher_decrypt(req);
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break;
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case kernel_pkey_sign:
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ret = crypto_akcipher_sign(req);
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break;
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default:
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BUG();
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}
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ret = crypto_wait_req(ret, &cwait);
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if (ret == 0)
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ret = req->dst_len;
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error_free_key:
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kfree(key);
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error_free_req:
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akcipher_request_free(req);
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error_free_tfm:
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crypto_free_akcipher(tfm);
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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#if IS_REACHABLE(CONFIG_CRYPTO_SM2)
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static int cert_sig_digest_update(const struct public_key_signature *sig,
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struct crypto_akcipher *tfm_pkey)
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{
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struct crypto_shash *tfm;
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struct shash_desc *desc;
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size_t desc_size;
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unsigned char dgst[SM3_DIGEST_SIZE];
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int ret;
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BUG_ON(!sig->data);
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/* SM2 signatures always use the SM3 hash algorithm */
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if (!sig->hash_algo || strcmp(sig->hash_algo, "sm3") != 0)
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return -EINVAL;
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ret = sm2_compute_z_digest(tfm_pkey, SM2_DEFAULT_USERID,
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SM2_DEFAULT_USERID_LEN, dgst);
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if (ret)
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return ret;
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tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
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desc = kzalloc(desc_size, GFP_KERNEL);
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if (!desc) {
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ret = -ENOMEM;
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goto error_free_tfm;
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}
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desc->tfm = tfm;
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ret = crypto_shash_init(desc);
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if (ret < 0)
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goto error_free_desc;
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ret = crypto_shash_update(desc, dgst, SM3_DIGEST_SIZE);
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if (ret < 0)
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goto error_free_desc;
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ret = crypto_shash_finup(desc, sig->data, sig->data_size, sig->digest);
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error_free_desc:
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kfree(desc);
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error_free_tfm:
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crypto_free_shash(tfm);
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return ret;
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}
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#else
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static inline int cert_sig_digest_update(
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const struct public_key_signature *sig,
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struct crypto_akcipher *tfm_pkey)
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{
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return -ENOTSUPP;
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}
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#endif /* ! IS_REACHABLE(CONFIG_CRYPTO_SM2) */
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/*
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* Verify a signature using a public key.
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*/
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int public_key_verify_signature(const struct public_key *pkey,
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const struct public_key_signature *sig)
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{
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struct crypto_wait cwait;
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struct crypto_akcipher *tfm;
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struct akcipher_request *req;
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struct scatterlist src_sg[2];
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char alg_name[CRYPTO_MAX_ALG_NAME];
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char *key, *ptr;
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int ret;
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pr_devel("==>%s()\n", __func__);
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BUG_ON(!pkey);
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BUG_ON(!sig);
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BUG_ON(!sig->s);
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/*
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* If the signature specifies a public key algorithm, it *must* match
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* the key's actual public key algorithm.
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*
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* Small exception: ECDSA signatures don't specify the curve, but ECDSA
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* keys do. So the strings can mismatch slightly in that case:
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* "ecdsa-nist-*" for the key, but "ecdsa" for the signature.
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*/
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if (sig->pkey_algo) {
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if (strcmp(pkey->pkey_algo, sig->pkey_algo) != 0 &&
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(strncmp(pkey->pkey_algo, "ecdsa-", 6) != 0 ||
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strcmp(sig->pkey_algo, "ecdsa") != 0))
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return -EKEYREJECTED;
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}
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ret = software_key_determine_akcipher(pkey, sig->encoding,
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sig->hash_algo, alg_name);
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if (ret < 0)
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return ret;
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tfm = crypto_alloc_akcipher(alg_name, 0, 0);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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ret = -ENOMEM;
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req = akcipher_request_alloc(tfm, GFP_KERNEL);
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if (!req)
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goto error_free_tfm;
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key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
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GFP_KERNEL);
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if (!key)
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goto error_free_req;
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memcpy(key, pkey->key, pkey->keylen);
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ptr = key + pkey->keylen;
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ptr = pkey_pack_u32(ptr, pkey->algo);
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ptr = pkey_pack_u32(ptr, pkey->paramlen);
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memcpy(ptr, pkey->params, pkey->paramlen);
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if (pkey->key_is_private)
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ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
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else
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ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
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if (ret)
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goto error_free_key;
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if (strcmp(pkey->pkey_algo, "sm2") == 0 && sig->data_size) {
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ret = cert_sig_digest_update(sig, tfm);
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if (ret)
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goto error_free_key;
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}
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sg_init_table(src_sg, 2);
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sg_set_buf(&src_sg[0], sig->s, sig->s_size);
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sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
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akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
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sig->digest_size);
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crypto_init_wait(&cwait);
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akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
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CRYPTO_TFM_REQ_MAY_SLEEP,
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crypto_req_done, &cwait);
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ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
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error_free_key:
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kfree(key);
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error_free_req:
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akcipher_request_free(req);
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error_free_tfm:
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crypto_free_akcipher(tfm);
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pr_devel("<==%s() = %d\n", __func__, ret);
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if (WARN_ON_ONCE(ret > 0))
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ret = -EINVAL;
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return ret;
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}
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EXPORT_SYMBOL_GPL(public_key_verify_signature);
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static int public_key_verify_signature_2(const struct key *key,
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const struct public_key_signature *sig)
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{
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const struct public_key *pk = key->payload.data[asym_crypto];
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return public_key_verify_signature(pk, sig);
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}
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/*
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* Public key algorithm asymmetric key subtype
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*/
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struct asymmetric_key_subtype public_key_subtype = {
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.owner = THIS_MODULE,
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.name = "public_key",
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.name_len = sizeof("public_key") - 1,
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.describe = public_key_describe,
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.destroy = public_key_destroy,
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.query = software_key_query,
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.eds_op = software_key_eds_op,
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.verify_signature = public_key_verify_signature_2,
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};
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EXPORT_SYMBOL_GPL(public_key_subtype);
|