crypto/asymmetric_keys/public_key.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* In-software asymmetric public-key crypto subtype
  *
  * See Documentation/crypto/asymmetric-keys.rst
  *
  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */

 #define pr_fmt(fmt) "PKEY: "fmt
 #include <crypto/akcipher.h>
 #include <crypto/public_key.h>
 #include <crypto/sig.h>
 #include <keys/asymmetric-subtype.h>
 #include <linux/asn1.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/string.h>

 MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
 MODULE_AUTHOR("Red Hat, Inc.");
 MODULE_LICENSE("GPL");

 /*
  * Provide a part of a description of the key for /proc/keys.
  */
 static void public_key_describe(const struct key *asymmetric_key,
 				struct seq_file *m)
 {
 	struct public_key *key = asymmetric_key->payload.data[asym_crypto];

 	if (key)
 		seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
 }

 /*
  * Destroy a public key algorithm key.
  */
 void public_key_free(struct public_key *key)
 {
 	if (key) {
 		kfree_sensitive(key->key);
 		kfree(key->params);
 		kfree(key);
 	}
 }
 EXPORT_SYMBOL_GPL(public_key_free);

 /*
  * Destroy a public key algorithm key.
  */
 static void public_key_destroy(void *payload0, void *payload3)
 {
 	public_key_free(payload0);
 	public_key_signature_free(payload3);
 }

 /*
  * 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 struct public_key *pkey,
 				const char *encoding, const char *hash_algo,
 				char alg_name[CRYPTO_MAX_ALG_NAME], bool *sig,
 				enum kernel_pkey_operation op)
 {
 	int n;

 	*sig = true;

 	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) {
 			*sig = op == kernel_pkey_sign ||
 			       op == kernel_pkey_verify;
 			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;
 		*sig = false;
 	} 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)
 			return -EINVAL;
 		if (strcmp(hash_algo, "sha224") != 0 &&
 		    strcmp(hash_algo, "sha256") != 0 &&
 		    strcmp(hash_algo, "sha384") != 0 &&
 		    strcmp(hash_algo, "sha512") != 0 &&
 		    strcmp(hash_algo, "sha3-256") != 0 &&
 		    strcmp(hash_algo, "sha3-384") != 0 &&
 		    strcmp(hash_algo, "sha3-512") != 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;
 	}
 	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)
 {
 	memcpy(dst, &val, sizeof(val));
 	return dst + sizeof(val);
 }

 /*
  * Query information about a key.
  */
 static int software_key_query(const struct kernel_pkey_params *params,
 			      struct kernel_pkey_query *info)
 {
 	struct crypto_akcipher *tfm;
 	struct public_key *pkey = params->key->payload.data[asym_crypto];
 	char alg_name[CRYPTO_MAX_ALG_NAME];
 	struct crypto_sig *sig;
 	u8 *key, *ptr;
 	int ret, len;
 	bool issig;

 	ret = software_key_determine_akcipher(pkey, params->encoding,
 					      params->hash_algo, alg_name,
 					      &issig, kernel_pkey_sign);
 	if (ret < 0)
 		return ret;

 	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 		      GFP_KERNEL);
 	if (!key)
 		return -ENOMEM;

 	memcpy(key, pkey->key, pkey->keylen);
 	ptr = key + pkey->keylen;
 	ptr = pkey_pack_u32(ptr, pkey->algo);
 	ptr = pkey_pack_u32(ptr, pkey->paramlen);
 	memcpy(ptr, pkey->params, pkey->paramlen);

 	if (issig) {
 		sig = crypto_alloc_sig(alg_name, 0, 0);
 		if (IS_ERR(sig)) {
 			ret = PTR_ERR(sig);
 			goto error_free_key;
 		}

 		if (pkey->key_is_private)
 			ret = crypto_sig_set_privkey(sig, key, pkey->keylen);
 		else
 			ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);
 		if (ret < 0)
 			goto error_free_tfm;

 		len = crypto_sig_maxsize(sig);

 		info->supported_ops = KEYCTL_SUPPORTS_VERIFY;
 		if (pkey->key_is_private)
 			info->supported_ops |= KEYCTL_SUPPORTS_SIGN;

 		if (strcmp(params->encoding, "pkcs1") == 0) {
 			info->supported_ops |= KEYCTL_SUPPORTS_ENCRYPT;
 			if (pkey->key_is_private)
 				info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
 		}
 	} else {
 		tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 		if (IS_ERR(tfm)) {
 			ret = PTR_ERR(tfm);
 			goto error_free_key;
 		}

 		if (pkey->key_is_private)
 			ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
 		else
 			ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
 		if (ret < 0)
 			goto error_free_tfm;

 		len = crypto_akcipher_maxsize(tfm);

 		info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT;
 		if (pkey->key_is_private)
 			info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
 	}

 	info->key_size = len * 8;

 	if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
 		/*
 		 * ECDSA key sizes are much smaller than RSA, and thus could
 		 * operate on (hashed) inputs that are larger than key size.
 		 * For example SHA384-hashed input used with secp256r1
 		 * based keys.  Set max_data_size to be at least as large as
 		 * the largest supported hash size (SHA512)
 		 */
 		info->max_data_size = 64;

 		/*
 		 * Verify takes ECDSA-Sig (described in RFC 5480) as input,
 		 * which is actually 2 'key_size'-bit integers encoded in
 		 * ASN.1.  Account for the ASN.1 encoding overhead here.
 		 */
 		info->max_sig_size = 2 * (len + 3) + 2;
 	} else {
 		info->max_data_size = len;
 		info->max_sig_size = len;
 	}

 	info->max_enc_size = len;
 	info->max_dec_size = len;

 	ret = 0;

 error_free_tfm:
 	if (issig)
 		crypto_free_sig(sig);
 	else
 		crypto_free_akcipher(tfm);
 error_free_key:
 	kfree_sensitive(key);
 	pr_devel("<==%s() = %d\n", __func__, ret);
 	return ret;
 }

 /*
  * Do encryption, decryption and signing ops.
  */
 static int software_key_eds_op(struct kernel_pkey_params *params,
 			       const void *in, void *out)
 {
 	const struct public_key *pkey = params->key->payload.data[asym_crypto];
 	char alg_name[CRYPTO_MAX_ALG_NAME];
 	struct crypto_akcipher *tfm;
 	struct crypto_sig *sig;
 	char *key, *ptr;
 	bool issig;
 	int ksz;
 	int ret;

 	pr_devel("==>%s()\n", __func__);

 	ret = software_key_determine_akcipher(pkey, params->encoding,
 					      params->hash_algo, alg_name,
 					      &issig, params->op);
 	if (ret < 0)
 		return ret;

 	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 		      GFP_KERNEL);
 	if (!key)
 		return -ENOMEM;

 	memcpy(key, pkey->key, pkey->keylen);
 	ptr = key + pkey->keylen;
 	ptr = pkey_pack_u32(ptr, pkey->algo);
 	ptr = pkey_pack_u32(ptr, pkey->paramlen);
 	memcpy(ptr, pkey->params, pkey->paramlen);

 	if (issig) {
 		sig = crypto_alloc_sig(alg_name, 0, 0);
 		if (IS_ERR(sig)) {
 			ret = PTR_ERR(sig);
 			goto error_free_key;
 		}

 		if (pkey->key_is_private)
 			ret = crypto_sig_set_privkey(sig, key, pkey->keylen);
 		else
 			ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);
 		if (ret)
 			goto error_free_tfm;

 		ksz = crypto_sig_maxsize(sig);
 	} else {
 		tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 		if (IS_ERR(tfm)) {
 			ret = PTR_ERR(tfm);
 			goto error_free_key;
 		}

 		if (pkey->key_is_private)
 			ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
 		else
 			ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
 		if (ret)
 			goto error_free_tfm;

 		ksz = crypto_akcipher_maxsize(tfm);
 	}

 	ret = -EINVAL;

 	/* Perform the encryption calculation. */
 	switch (params->op) {
 	case kernel_pkey_encrypt:
 		if (issig)
 			break;
 		ret = crypto_akcipher_sync_encrypt(tfm, in, params->in_len,
 						   out, params->out_len);
 		break;
 	case kernel_pkey_decrypt:
 		if (issig)
 			break;
 		ret = crypto_akcipher_sync_decrypt(tfm, in, params->in_len,
 						   out, params->out_len);
 		break;
 	case kernel_pkey_sign:
 		if (!issig)
 			break;
 		ret = crypto_sig_sign(sig, in, params->in_len,
 				      out, params->out_len);
 		break;
 	default:
 		BUG();
 	}

 	if (ret == 0)
 		ret = ksz;

 error_free_tfm:
 	if (issig)
 		crypto_free_sig(sig);
 	else
 		crypto_free_akcipher(tfm);
 error_free_key:
 	kfree_sensitive(key);
 	pr_devel("<==%s() = %d\n", __func__, ret);
 	return ret;
 }

 /*
  * Verify a signature using a public key.
  */
 int public_key_verify_signature(const struct public_key *pkey,
 				const struct public_key_signature *sig)
 {
 	char alg_name[CRYPTO_MAX_ALG_NAME];
 	struct crypto_sig *tfm;
 	char *key, *ptr;
 	bool issig;
 	int ret;

 	pr_devel("==>%s()\n", __func__);

 	BUG_ON(!pkey);
 	BUG_ON(!sig);
 	BUG_ON(!sig->s);

 	/*
 	 * 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,
 					      &issig, kernel_pkey_verify);
 	if (ret < 0)
 		return ret;

 	tfm = crypto_alloc_sig(alg_name, 0, 0);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 		      GFP_KERNEL);
 	if (!key) {
 		ret = -ENOMEM;
 		goto error_free_tfm;
 	}

 	memcpy(key, pkey->key, pkey->keylen);
 	ptr = key + pkey->keylen;
 	ptr = pkey_pack_u32(ptr, pkey->algo);
 	ptr = pkey_pack_u32(ptr, pkey->paramlen);
 	memcpy(ptr, pkey->params, pkey->paramlen);

 	if (pkey->key_is_private)
 		ret = crypto_sig_set_privkey(tfm, key, pkey->keylen);
 	else
 		ret = crypto_sig_set_pubkey(tfm, key, pkey->keylen);
 	if (ret)
 		goto error_free_key;

 	ret = crypto_sig_verify(tfm, sig->s, sig->s_size,
 				sig->digest, sig->digest_size);

 error_free_key:
 	kfree_sensitive(key);
 error_free_tfm:
 	crypto_free_sig(tfm);
 	pr_devel("<==%s() = %d\n", __func__, ret);
 	if (WARN_ON_ONCE(ret > 0))
 		ret = -EINVAL;
 	return ret;
 }
 EXPORT_SYMBOL_GPL(public_key_verify_signature);

 static int public_key_verify_signature_2(const struct key *key,
 					 const struct public_key_signature *sig)
 {
 	const struct public_key *pk = key->payload.data[asym_crypto];
 	return public_key_verify_signature(pk, sig);
 }

 /*
  * Public key algorithm asymmetric key subtype
  */
 struct asymmetric_key_subtype public_key_subtype = {
 	.owner			= THIS_MODULE,
 	.name			= "public_key",
 	.name_len		= sizeof("public_key") - 1,
 	.describe		= public_key_describe,
 	.destroy		= public_key_destroy,
 	.query			= software_key_query,
 	.eds_op			= software_key_eds_op,
 	.verify_signature	= public_key_verify_signature_2,
 };
 EXPORT_SYMBOL_GPL(public_key_subtype);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* In-software asymmetric public-key crypto subtype
	*
	* See Documentation/crypto/asymmetric-keys.rst
	*
	* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*/

	#define pr_fmt(fmt) "PKEY: "fmt
	#include <crypto/akcipher.h>
	#include <crypto/public_key.h>
	#include <crypto/sig.h>
	#include <keys/asymmetric-subtype.h>
	#include <linux/asn1.h>
	#include <linux/err.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>
	#include <linux/string.h>

	MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
	MODULE_AUTHOR("Red Hat, Inc.");
	MODULE_LICENSE("GPL");

	/*
	* Provide a part of a description of the key for /proc/keys.
	*/
	static void public_key_describe(const struct key *asymmetric_key,
	struct seq_file *m)
	{
	struct public_key *key = asymmetric_key->payload.data[asym_crypto];

	if (key)
	seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
	}

	/*
	* Destroy a public key algorithm key.
	*/
	void public_key_free(struct public_key *key)
	{
	if (key) {
	kfree_sensitive(key->key);
	kfree(key->params);
	kfree(key);
	}
	}
	EXPORT_SYMBOL_GPL(public_key_free);

	/*
	* Destroy a public key algorithm key.
	*/
	static void public_key_destroy(void payload0, void payload3)
	{
	public_key_free(payload0);
	public_key_signature_free(payload3);
	}

	/*
	* 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 struct public_key *pkey,
	const char encoding, const char hash_algo,
	char alg_name[CRYPTO_MAX_ALG_NAME], bool *sig,
	enum kernel_pkey_operation op)
	{
	int n;

	*sig = true;

	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) {
	*sig = op == kernel_pkey_sign \|\|
	op == kernel_pkey_verify;
	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;
	*sig = false;
	} 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)
	return -EINVAL;
	if (strcmp(hash_algo, "sha224") != 0 &&
	strcmp(hash_algo, "sha256") != 0 &&
	strcmp(hash_algo, "sha384") != 0 &&
	strcmp(hash_algo, "sha512") != 0 &&
	strcmp(hash_algo, "sha3-256") != 0 &&
	strcmp(hash_algo, "sha3-384") != 0 &&
	strcmp(hash_algo, "sha3-512") != 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;
	}
	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)
	{
	memcpy(dst, &val, sizeof(val));
	return dst + sizeof(val);
	}

	/*
	* Query information about a key.
	*/
	static int software_key_query(const struct kernel_pkey_params *params,
	struct kernel_pkey_query *info)
	{
	struct crypto_akcipher *tfm;
	struct public_key *pkey = params->key->payload.data[asym_crypto];
	char alg_name[CRYPTO_MAX_ALG_NAME];
	struct crypto_sig *sig;
	u8 key, ptr;
	int ret, len;
	bool issig;

	ret = software_key_determine_akcipher(pkey, params->encoding,
	params->hash_algo, alg_name,
	&issig, kernel_pkey_sign);
	if (ret < 0)
	return ret;

	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
	GFP_KERNEL);
	if (!key)
	return -ENOMEM;

	memcpy(key, pkey->key, pkey->keylen);
	ptr = key + pkey->keylen;
	ptr = pkey_pack_u32(ptr, pkey->algo);
	ptr = pkey_pack_u32(ptr, pkey->paramlen);
	memcpy(ptr, pkey->params, pkey->paramlen);

	if (issig) {
	sig = crypto_alloc_sig(alg_name, 0, 0);
	if (IS_ERR(sig)) {
	ret = PTR_ERR(sig);
	goto error_free_key;
	}

	if (pkey->key_is_private)
	ret = crypto_sig_set_privkey(sig, key, pkey->keylen);
	else
	ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);
	if (ret < 0)
	goto error_free_tfm;

	len = crypto_sig_maxsize(sig);

	info->supported_ops = KEYCTL_SUPPORTS_VERIFY;
	if (pkey->key_is_private)
	info->supported_ops \|= KEYCTL_SUPPORTS_SIGN;

	if (strcmp(params->encoding, "pkcs1") == 0) {
	info->supported_ops \|= KEYCTL_SUPPORTS_ENCRYPT;
	if (pkey->key_is_private)
	info->supported_ops \|= KEYCTL_SUPPORTS_DECRYPT;
	}
	} else {
	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
	if (IS_ERR(tfm)) {
	ret = PTR_ERR(tfm);
	goto error_free_key;
	}

	if (pkey->key_is_private)
	ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
	else
	ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
	if (ret < 0)
	goto error_free_tfm;

	len = crypto_akcipher_maxsize(tfm);

	info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT;
	if (pkey->key_is_private)
	info->supported_ops \|= KEYCTL_SUPPORTS_DECRYPT;
	}

	info->key_size = len * 8;

	if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
	/*
	* ECDSA key sizes are much smaller than RSA, and thus could
	* operate on (hashed) inputs that are larger than key size.
	* For example SHA384-hashed input used with secp256r1
	* based keys. Set max_data_size to be at least as large as
	* the largest supported hash size (SHA512)
	*/
	info->max_data_size = 64;

	/*
	* Verify takes ECDSA-Sig (described in RFC 5480) as input,
	* which is actually 2 'key_size'-bit integers encoded in
	* ASN.1. Account for the ASN.1 encoding overhead here.
	*/
	info->max_sig_size = 2 * (len + 3) + 2;
	} else {
	info->max_data_size = len;
	info->max_sig_size = len;
	}

	info->max_enc_size = len;
	info->max_dec_size = len;

	ret = 0;

	error_free_tfm:
	if (issig)
	crypto_free_sig(sig);
	else
	crypto_free_akcipher(tfm);
	error_free_key:
	kfree_sensitive(key);
	pr_devel("<==%s() = %d\n", __func__, ret);
	return ret;
	}

	/*
	* Do encryption, decryption and signing ops.
	*/
	static int software_key_eds_op(struct kernel_pkey_params *params,
	const void in, void out)
	{
	const struct public_key *pkey = params->key->payload.data[asym_crypto];
	char alg_name[CRYPTO_MAX_ALG_NAME];
	struct crypto_akcipher *tfm;
	struct crypto_sig *sig;
	char key, ptr;
	bool issig;
	int ksz;
	int ret;

	pr_devel("==>%s()\n", __func__);

	ret = software_key_determine_akcipher(pkey, params->encoding,
	params->hash_algo, alg_name,
	&issig, params->op);
	if (ret < 0)
	return ret;

	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
	GFP_KERNEL);
	if (!key)
	return -ENOMEM;

	memcpy(key, pkey->key, pkey->keylen);
	ptr = key + pkey->keylen;
	ptr = pkey_pack_u32(ptr, pkey->algo);
	ptr = pkey_pack_u32(ptr, pkey->paramlen);
	memcpy(ptr, pkey->params, pkey->paramlen);

	if (issig) {
	sig = crypto_alloc_sig(alg_name, 0, 0);
	if (IS_ERR(sig)) {
	ret = PTR_ERR(sig);
	goto error_free_key;
	}

	if (pkey->key_is_private)
	ret = crypto_sig_set_privkey(sig, key, pkey->keylen);
	else
	ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);
	if (ret)
	goto error_free_tfm;

	ksz = crypto_sig_maxsize(sig);
	} else {
	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
	if (IS_ERR(tfm)) {
	ret = PTR_ERR(tfm);
	goto error_free_key;
	}

	if (pkey->key_is_private)
	ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
	else
	ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
	if (ret)
	goto error_free_tfm;

	ksz = crypto_akcipher_maxsize(tfm);
	}

	ret = -EINVAL;

	/* Perform the encryption calculation. */
	switch (params->op) {
	case kernel_pkey_encrypt:
	if (issig)
	break;
	ret = crypto_akcipher_sync_encrypt(tfm, in, params->in_len,
	out, params->out_len);
	break;
	case kernel_pkey_decrypt:
	if (issig)
	break;
	ret = crypto_akcipher_sync_decrypt(tfm, in, params->in_len,
	out, params->out_len);
	break;
	case kernel_pkey_sign:
	if (!issig)
	break;
	ret = crypto_sig_sign(sig, in, params->in_len,
	out, params->out_len);
	break;
	default:
	BUG();
	}

	if (ret == 0)
	ret = ksz;

	error_free_tfm:
	if (issig)
	crypto_free_sig(sig);
	else
	crypto_free_akcipher(tfm);
	error_free_key:
	kfree_sensitive(key);
	pr_devel("<==%s() = %d\n", __func__, ret);
	return ret;
	}

	/*
	* Verify a signature using a public key.
	*/
	int public_key_verify_signature(const struct public_key *pkey,
	const struct public_key_signature *sig)
	{
	char alg_name[CRYPTO_MAX_ALG_NAME];
	struct crypto_sig *tfm;
	char key, ptr;
	bool issig;
	int ret;

	pr_devel("==>%s()\n", __func__);

	BUG_ON(!pkey);
	BUG_ON(!sig);
	BUG_ON(!sig->s);

	/*
	* 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,
	&issig, kernel_pkey_verify);
	if (ret < 0)
	return ret;

	tfm = crypto_alloc_sig(alg_name, 0, 0);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
	GFP_KERNEL);
	if (!key) {
	ret = -ENOMEM;
	goto error_free_tfm;
	}

	memcpy(key, pkey->key, pkey->keylen);
	ptr = key + pkey->keylen;
	ptr = pkey_pack_u32(ptr, pkey->algo);
	ptr = pkey_pack_u32(ptr, pkey->paramlen);
	memcpy(ptr, pkey->params, pkey->paramlen);

	if (pkey->key_is_private)
	ret = crypto_sig_set_privkey(tfm, key, pkey->keylen);
	else
	ret = crypto_sig_set_pubkey(tfm, key, pkey->keylen);
	if (ret)
	goto error_free_key;

	ret = crypto_sig_verify(tfm, sig->s, sig->s_size,
	sig->digest, sig->digest_size);

	error_free_key:
	kfree_sensitive(key);
	error_free_tfm:
	crypto_free_sig(tfm);
	pr_devel("<==%s() = %d\n", __func__, ret);
	if (WARN_ON_ONCE(ret > 0))
	ret = -EINVAL;
	return ret;
	}
	EXPORT_SYMBOL_GPL(public_key_verify_signature);

	static int public_key_verify_signature_2(const struct key *key,
	const struct public_key_signature *sig)
	{
	const struct public_key *pk = key->payload.data[asym_crypto];
	return public_key_verify_signature(pk, sig);
	}

	/*
	* Public key algorithm asymmetric key subtype
	*/
	struct asymmetric_key_subtype public_key_subtype = {
	.owner = THIS_MODULE,
	.name = "public_key",
	.name_len = sizeof("public_key") - 1,
	.describe = public_key_describe,
	.destroy = public_key_destroy,
	.query = software_key_query,
	.eds_op = software_key_eds_op,
	.verify_signature = public_key_verify_signature_2,
	};
	EXPORT_SYMBOL_GPL(public_key_subtype);