1 files changed, 161 insertions, 35 deletions

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index d7f43d4ea925..2f8352e88860 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /* In-software asymmetric public-key crypto subtype
  *
- * See Documentation/crypto/asymmetric-keys.txt
+ * See Documentation/crypto/asymmetric-keys.rst
  *
  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
@@ -14,9 +14,12 @@
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 #include <linux/scatterlist.h>
+#include <linux/asn1.h>
 #include <keys/asymmetric-subtype.h>
 #include <crypto/public_key.h>
 #include <crypto/akcipher.h>
+#include <crypto/sm2.h>
+#include <crypto/sm3_base.h>
 
 MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
 MODULE_AUTHOR("Red Hat, Inc.");
@@ -57,38 +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);
+			else
+				n = 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;
+		/*
+		 * 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.
 		 */
 		if (!hash_algo)
-			n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
-				     "pkcs1pad(%s)",
-				     pkey->pkey_algo);
-		else
-			n = 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) {
-		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)
@@ -109,9 +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);
 	if (ret < 0)
 		return ret;
 
@@ -119,6 +166,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);
 
+	ret = -ENOMEM;
 	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 		      GFP_KERNEL);
 	if (!key)
@@ -174,9 +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);
 	if (ret < 0)
 		return ret;
 
@@ -245,6 +292,65 @@ error_free_tfm:
 	return ret;
 }
 
+#if IS_REACHABLE(CONFIG_CRYPTO_SM2)
+static int cert_sig_digest_update(const struct public_key_signature *sig,
+				  struct crypto_akcipher *tfm_pkey)
+{
+	struct crypto_shash *tfm;
+	struct shash_desc *desc;
+	size_t desc_size;
+	unsigned char dgst[SM3_DIGEST_SIZE];
+	int ret;
+
+	BUG_ON(!sig->data);
+
+	/* SM2 signatures always use the SM3 hash algorithm */
+	if (!sig->hash_algo || strcmp(sig->hash_algo, "sm3") != 0)
+		return -EINVAL;
+
+	ret = sm2_compute_z_digest(tfm_pkey, SM2_DEFAULT_USERID,
+					SM2_DEFAULT_USERID_LEN, dgst);
+	if (ret)
+		return ret;
+
+	tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
+	desc = kzalloc(desc_size, GFP_KERNEL);
+	if (!desc) {
+		ret = -ENOMEM;
+		goto error_free_tfm;
+	}
+
+	desc->tfm = tfm;
+
+	ret = crypto_shash_init(desc);
+	if (ret < 0)
+		goto error_free_desc;
+
+	ret = crypto_shash_update(desc, dgst, SM3_DIGEST_SIZE);
+	if (ret < 0)
+		goto error_free_desc;
+
+	ret = crypto_shash_finup(desc, sig->data, sig->data_size, sig->digest);
+
+error_free_desc:
+	kfree(desc);
+error_free_tfm:
+	crypto_free_shash(tfm);
+	return ret;
+}
+#else
+static inline int cert_sig_digest_update(
+	const struct public_key_signature *sig,
+	struct crypto_akcipher *tfm_pkey)
+{
+	return -ENOTSUPP;
+}
+#endif /* ! IS_REACHABLE(CONFIG_CRYPTO_SM2) */
+
 /*
  * Verify a signature using a public key.
  */
@@ -265,9 +371,23 @@ int public_key_verify_signature(const struct public_key *pkey,
 	BUG_ON(!sig);
 	BUG_ON(!sig->s);
 
-	ret = software_key_determine_akcipher(sig->encoding,
-					      sig->hash_algo,
-					      pkey, alg_name);
+	/*
+	 * If the signature specifies a public key algorithm, it *must* match
+	 * the key's actual public key algorithm.
+	 *
+	 * Small exception: ECDSA signatures don't specify the curve, but ECDSA
+	 * keys do.  So the strings can mismatch slightly in that case:
+	 * "ecdsa-nist-*" for the key, but "ecdsa" for the signature.
+	 */
+	if (sig->pkey_algo) {
+		if (strcmp(pkey->pkey_algo, sig->pkey_algo) != 0 &&
+		    (strncmp(pkey->pkey_algo, "ecdsa-", 6) != 0 ||
+		     strcmp(sig->pkey_algo, "ecdsa") != 0))
+			return -EKEYREJECTED;
+	}
+
+	ret = software_key_determine_akcipher(pkey, sig->encoding,
+					      sig->hash_algo, alg_name);
 	if (ret < 0)
 		return ret;
 
@@ -298,6 +418,12 @@ int public_key_verify_signature(const struct public_key *pkey,
 	if (ret)
 		goto error_free_key;
 
+	if (strcmp(pkey->pkey_algo, "sm2") == 0 && sig->data_size) {
+		ret = cert_sig_digest_update(sig, tfm);
+		if (ret)
+			goto error_free_key;
+	}
+
 	sg_init_table(src_sg, 2);
 	sg_set_buf(&src_sg[0], sig->s, sig->s_size);
 	sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);