[RFC,v3,5/9] KEYS: asymmetric: Introduce the user asymmetric key signature parser

diff --git a/MAINTAINERS b/MAINTAINERS
index 220463b2e51..d3af1e179b0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3143,6 +3143,7 @@  F:	Documentation/crypto/asymmetric-keys.rst
 F:	crypto/asymmetric_keys/
 F:	include/crypto/pkcs7.h
 F:	include/crypto/public_key.h
+F:	include/crypto/uasym_sig.h
 F:	include/linux/verification.h
 
 ASYNCHRONOUS TRANSFERS/TRANSFORMS (IOAT) API
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 4a5f66511d4..d9d82cada0a 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -89,6 +89,7 @@  config UASYM_KEYS_SIGS
 	tristate "User asymmetric keys and signatures"
 	depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
 	select CRYPTO_PUB_KEY_INFO
+	select CRYPTO_SIG_ENC_INFO
 	select TLV_PARSER
 	help
 	  This option enables user asymmetric keys and signatures. They are
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 5ba30cca09e..191b7fe8359 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -81,4 +81,5 @@  $(obj)/mscode.asn1.o: $(obj)/mscode.asn1.c $(obj)/mscode.asn1.h
 # User asymmetric keys and signatures
 #
 obj-$(CONFIG_UASYM_KEYS_SIGS) += uasym_keys_sigs.o
-uasym_keys_sigs-y := uasym_key_parser.o
+uasym_keys_sigs-y := uasym_key_parser.o \
+		     uasym_sig_parser.o
diff --git a/crypto/asymmetric_keys/uasym_sig_parser.c b/crypto/asymmetric_keys/uasym_sig_parser.c
new file mode 100644
index 00000000000..97fa1381a78
--- /dev/null
+++ b/crypto/asymmetric_keys/uasym_sig_parser.c
@@ -0,0 +1,497 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2023 Huawei Technologies Duesseldorf GmbH
+ *
+ * Authors:
+ *   David Howells <dhowells@redhat.com>
+ *   Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the user asymmetric key signature parser.
+ */
+
+#define pr_fmt(fmt) "UASYM SIG: "fmt
+#include <linux/module.h>
+#include <linux/tlv_parser.h>
+#include <crypto/public_key.h>
+#include <crypto/uasym_keys_sigs.h>
+#include <crypto/pub_key_info.h>
+#include <crypto/sig_enc_info.h>
+#include <crypto/hash_info.h>
+#include <crypto/hash.h>
+
+#include "uasym_parser.h"
+
+struct uasym_sig_message {
+	struct public_key_signature *sig;
+	size_t data_len;
+	const void *data;
+	size_t sig_data_len;
+	const void *sig_data;
+};
+
+static int parse_sig_s(struct public_key_signature *sig, enum fields field,
+		       const u8 *field_data, u64 field_data_len)
+{
+	int ret = 0;
+
+	kenter(",%u,%llu", field, field_data_len);
+
+	sig->s = kmemdup(field_data, field_data_len, GFP_KERNEL);
+	if (!sig->s) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	sig->s_size = field_data_len;
+	pr_debug("Signature length: %d\n", sig->s_size);
+out:
+	kleave(" = %d", ret);
+	return ret;
+}
+
+static int parse_sig_hash_algo_size(struct public_key_signature *sig,
+				    enum fields field, const u8 *field_data,
+				    u64 field_data_len)
+{
+	u8 algo;
+	int ret = 0;
+
+	kenter(",%u,%llu", field, field_data_len);
+
+	if (field_data_len != sizeof(u8)) {
+		pr_debug("Unexpected data length %llu, expected %lu\n",
+			 field_data_len, sizeof(u8));
+		ret = -EBADMSG;
+		goto out;
+	}
+
+	algo = *field_data;
+
+	if (algo >= HASH_ALGO__LAST) {
+		pr_debug("Unexpected hash algo %u\n", algo);
+		ret = -EBADMSG;
+		goto out;
+	}
+
+	sig->hash_algo = hash_algo_name[algo];
+	sig->digest_size = hash_digest_size[algo];
+	pr_debug("Hash algo: %s, digest length: %d\n", sig->hash_algo,
+		 sig->digest_size);
+out:
+	kleave(" = %d", ret);
+	return ret;
+}
+
+static int parse_sig_enc(struct public_key_signature *sig, enum fields field,
+			 const u8 *field_data, u64 field_data_len)
+{
+	u8 enc;
+	int ret = 0;
+
+	kenter(",%u,%llu", field, field_data_len);
+
+	if (field_data_len != sizeof(u8)) {
+		pr_debug("Unexpected data length %llu, expected %lu\n",
+			 field_data_len, sizeof(u8));
+		ret = -EBADMSG;
+		goto out;
+	}
+
+	enc = *field_data;
+
+	if (enc >= SIG_ENC__LAST) {
+		pr_debug("Unexpected encoding %u\n", enc);
+		ret = -EBADMSG;
+		goto out;
+	}
+
+	sig->encoding = sig_enc_name[enc];
+	pr_debug("Signature encoding: %s\n", sig->encoding);
+out:
+	kleave(" = %d", ret);
+	return ret;
+}
+
+static int parse_sig_data_end(struct uasym_sig_message *uasym_sig,
+			      enum fields field, const u8 *field_data,
+			      u64 field_data_len)
+{
+	int ret = 0;
+
+	kenter(",%u,%llu", field, field_data_len);
+
+	uasym_sig->sig_data = kmemdup(field_data, field_data_len, GFP_KERNEL);
+	if (!uasym_sig->sig_data) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	uasym_sig->sig_data_len = field_data_len;
+	pr_debug("Signature data length appended at the end: %ld\n",
+		 uasym_sig->sig_data_len);
+out:
+	kleave(" = %d", ret);
+	return ret;
+}
+
+static int sig_callback(void *callback_data, u64 field, const u8 *field_data,
+			u64 field_data_len)
+{
+	struct uasym_sig_message *uasym_sig;
+	struct public_key_signature *sig;
+	struct asymmetric_key_id **id;
+	int ret;
+
+	uasym_sig = (struct uasym_sig_message *)callback_data;
+	sig = uasym_sig->sig;
+
+	switch (field) {
+	case SIG_S:
+		ret = parse_sig_s(sig, field, field_data, field_data_len);
+		break;
+	case SIG_KEY_ALGO:
+		ret = parse_key_algo(&sig->pkey_algo, field, field_data,
+				     field_data_len);
+		break;
+	case SIG_HASH_ALGO:
+		ret = parse_sig_hash_algo_size(sig, field, field_data,
+					       field_data_len);
+		break;
+	case SIG_ENC:
+		ret = parse_sig_enc(sig, field, field_data, field_data_len);
+		break;
+	case SIG_KID0:
+		id = (struct asymmetric_key_id **)&sig->auth_ids[0];
+		ret = parse_key_kid(id, field, field_data, field_data_len);
+		break;
+	case SIG_KID1:
+		id = (struct asymmetric_key_id **)&sig->auth_ids[1];
+		ret = parse_key_kid(id, field, field_data, field_data_len);
+		break;
+	case SIG_KID2:
+		id = (struct asymmetric_key_id **)&sig->auth_ids[2];
+		ret = parse_key_kid(id, field, field_data, field_data_len);
+		break;
+	case SIG_DATA_END:
+		ret = parse_sig_data_end(uasym_sig, field, field_data,
+					 field_data_len);
+		break;
+	default:
+		pr_debug("Unhandled field %llu\n", field);
+		/* Just ignore non-relevant fields. */
+		ret = 0;
+		break;
+	}
+
+	return ret;
+}
+
+/**
+ * uasym_sig_parse_message - Parse a user asymmetric key signature
+ * @sig_data: Signature blob
+ * @sig_len: Length of signature blob
+ *
+ * Parse a user asymmetric key signature and initialize the signature context.
+ *
+ * Return: A uasym_sig_message structure on success, an error pointer on error.
+ */
+struct uasym_sig_message *uasym_sig_parse_message(const u8 *sig_data,
+						  size_t sig_len)
+{
+	struct uasym_sig_message *uasym_sig = NULL;
+	struct public_key_signature *sig;
+	int ret = -EBADMSG;
+
+	kenter("");
+
+	uasym_sig = kzalloc(sizeof(*uasym_sig), GFP_KERNEL);
+	if (!uasym_sig) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	sig = kzalloc(sizeof(*sig), GFP_KERNEL);
+	if (!sig) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	uasym_sig->sig = sig;
+
+	ret = tlv_parse(TYPE_SIG, sig_callback, uasym_sig, sig_data, sig_len,
+			data_types_str, TYPE__LAST, fields_str, FIELD__LAST);
+	if (ret < 0)
+		goto out;
+
+	if (!sig->s || !sig->pkey_algo || !sig->hash_algo || !sig->encoding ||
+	    (!sig->auth_ids[0] && !sig->auth_ids[1] && !sig->auth_ids[2])) {
+		pr_debug("Incomplete data\n");
+		ret = -ENOENT;
+		goto out;
+	}
+out:
+	if (ret < 0) {
+		uasym_sig_free_message(uasym_sig);
+		uasym_sig = ERR_PTR(ret);
+		kleave(" = ERR_PTR(%d)", ret);
+	}
+
+	kleave(" = PTR(uasym_sig)");
+	return uasym_sig;
+}
+EXPORT_SYMBOL_GPL(uasym_sig_parse_message);
+
+/**
+ * uasym_sig_supply_detached_data - Supply data to verify a user asym key sig
+ * @uasym_sig: The signature context
+ * @data: The data to be verified
+ * @data_len: The amount of data
+ *
+ * Supply the detached data needed to verify a user asymmetric key signature.
+ * Note that no attempt to retain/pin the data is made. That is left to the
+ * caller. The data will not be modified by uasym_sig_verify_message() and will
+ * not be freed when the signature context is freed.
+ *
+ * Return: Zero on success, -EINVAL if data are already supplied.
+ */
+int uasym_sig_supply_detached_data(struct uasym_sig_message *uasym_sig,
+				   const void *data, size_t data_len)
+{
+	if (uasym_sig->data) {
+		pr_debug("Data already supplied\n");
+		return -EINVAL;
+	}
+
+	uasym_sig->data = data;
+	uasym_sig->data_len = data_len;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(uasym_sig_supply_detached_data);
+
+/**
+ * uasym_sig_get_content_data - Get access to content data and additional data
+ * @uasym_sig: The signature context
+ * @_data: Place to return a pointer to the data (updated)
+ * @_data_len: Place to return the data length (updated)
+ * @_headerlen: Size of the additional data (updated)
+ *
+ * Get access to the data associated to the user asymmetric key signature.
+ * This includes the content data eventually supplied by the caller of the user
+ * asymmetric key signatures API, and the additional data resulting from the
+ * signature parsing, appended at the end (more orderings can be supported
+ * in the future).
+ *
+ * Data is allocated, to concatenate together the two data sources, and must be
+ * freed by the caller. It is presented in a way that is suitable for
+ * calculating the digest for verifying the signature.
+ *
+ * Return: Zero if the data and additional data can be provided,
+ *         a negative value on error.
+ */
+int uasym_sig_get_content_data(struct uasym_sig_message *uasym_sig,
+			       const void **_data, size_t *_data_len,
+			       size_t *_headerlen)
+{
+	void *data;
+
+	if (!uasym_sig->data)
+		return -ENODATA;
+
+	if (!_data)
+		goto skip_data;
+
+	data = kmalloc(uasym_sig->data_len + uasym_sig->sig_data_len,
+		       GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memcpy(data, uasym_sig->data, uasym_sig->data_len);
+	memcpy(data + uasym_sig->data_len, uasym_sig->sig_data,
+	       uasym_sig->sig_data_len);
+	*_data = data;
+skip_data:
+	if (_data_len)
+		*_data_len = uasym_sig->data_len + uasym_sig->sig_data_len;
+	if (_headerlen)
+		*_headerlen = uasym_sig->data_len;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(uasym_sig_get_content_data);
+
+static int uasym_sig_digest(struct uasym_sig_message *uasym_sig)
+{
+	struct public_key_signature *sig = uasym_sig->sig;
+	struct crypto_shash *tfm;
+	struct shash_desc *desc;
+	size_t desc_size;
+	int ret;
+
+	/* The digest was calculated already. */
+	if (sig->digest)
+		return 0;
+
+	tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
+	if (IS_ERR(tfm))
+		return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
+
+	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
+
+	ret = -ENOMEM;
+	sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
+	if (!sig->digest)
+		goto error_no_desc;
+
+	desc = kzalloc(desc_size, GFP_KERNEL);
+	if (!desc)
+		goto error_no_desc;
+
+	desc->tfm = tfm;
+
+	ret = crypto_shash_init(desc);
+	if (ret < 0)
+		goto error;
+
+	ret = crypto_shash_update(desc, uasym_sig->data, uasym_sig->data_len);
+	if (ret < 0)
+		goto error;
+
+	if (uasym_sig->sig_data_len) {
+		ret = crypto_shash_update(desc, uasym_sig->sig_data,
+					  uasym_sig->sig_data_len);
+		if (ret < 0)
+			goto error;
+	}
+
+	ret = crypto_shash_final(desc, sig->digest);
+error:
+	kfree(desc);
+error_no_desc:
+	crypto_free_shash(tfm);
+	return ret;
+}
+
+/**
+ * uasym_sig_get_digest - Obtain the digest and algorithm of the data to verify
+ * @uasym_sig: The signature context
+ * @digest: The buffer the digest is written to
+ * @digest_len: The length of @digest
+ * @hash_algo: The algorithm the digest is calculated with
+ *
+ * Calculate the digest of data to verify with the user asymmetric key
+ * signature, if not calculated already. Pass the pointer of the digest from
+ * the public_key_signature structure, the length and the algorithm to the
+ * caller.
+ *
+ * Return: Zero on success, a negative value otherwise.
+ */
+int uasym_sig_get_digest(struct uasym_sig_message *uasym_sig, const u8 **digest,
+			 u32 *digest_len, enum hash_algo *hash_algo)
+{
+	struct public_key_signature *sig = uasym_sig->sig;
+	int i, ret;
+
+	ret = uasym_sig_digest(uasym_sig);
+	if (ret)
+		return ret;
+
+	*digest = sig->digest;
+	*digest_len = sig->digest_size;
+
+	i = match_string(hash_algo_name, HASH_ALGO__LAST, sig->hash_algo);
+	if (i >= 0)
+		*hash_algo = i;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(uasym_sig_get_digest);
+
+static struct key *get_key(struct uasym_sig_message *uasym_sig,
+			   struct key *keyring)
+{
+	struct public_key_signature *sig = uasym_sig->sig;
+	struct key *key;
+
+	key = find_asymmetric_key(keyring, sig->auth_ids[0], sig->auth_ids[1],
+				  sig->auth_ids[2], false);
+	if (IS_ERR(key)) {
+		pr_debug("Public key not found (%*phN, %*phN, %*phN)\n",
+			 sig->auth_ids[0] ? sig->auth_ids[0]->len : 0,
+			 sig->auth_ids[0] ? sig->auth_ids[0]->data : NULL,
+			 sig->auth_ids[1] ? sig->auth_ids[1]->len : 0,
+			 sig->auth_ids[1] ? sig->auth_ids[1]->data : NULL,
+			 sig->auth_ids[2] ? sig->auth_ids[2]->len : 0,
+			 sig->auth_ids[2] ? sig->auth_ids[2]->data : NULL);
+
+		switch (PTR_ERR(key)) {
+			/* Hide some search errors */
+		case -EACCES:
+		case -ENOTDIR:
+		case -EAGAIN:
+			return ERR_PTR(-ENOKEY);
+		default:
+			return ERR_CAST(key);
+		}
+	}
+
+	return key;
+}
+
+/**
+ * uasym_sig_verify_message - Verify the user asymmetric key signature
+ * @uasym_sig: The signature context
+ * @keyring: Keyring containing the key for signature verification
+ *
+ * Calculate the digest, search the key for signature verification, and verify
+ * the signature.
+ *
+ * Return: Zero if the signature is valid, a negative value otherwise.
+ */
+int uasym_sig_verify_message(struct uasym_sig_message *uasym_sig,
+			     struct key *keyring)
+{
+	const struct public_key *pub;
+	struct key *key;
+	int ret;
+
+	ret = uasym_sig_digest(uasym_sig);
+	if (ret < 0)
+		return ret;
+
+	key = get_key(uasym_sig, keyring);
+	if (IS_ERR(key))
+		return PTR_ERR(key);
+
+	pub = key->payload.data[asym_crypto];
+
+	if (strcmp(pub->pkey_algo, uasym_sig->sig->pkey_algo) != 0 &&
+	    (strncmp(pub->pkey_algo, "ecdsa-", 6) != 0 ||
+	     strcmp(uasym_sig->sig->pkey_algo, "ecdsa") != 0)) {
+		ret = -EKEYREJECTED;
+		goto out;
+	}
+
+	ret = verify_signature(key, uasym_sig->sig);
+out:
+	key_put(key);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(uasym_sig_verify_message);
+
+/**
+ * uasym_sig_free_message - Free the memory allocated
+ * @uasym_sig: The signature context
+ *
+ * Free the memory allocated for the verification of the user asymmetric key
+ * signature.
+ */
+void uasym_sig_free_message(struct uasym_sig_message *uasym_sig)
+{
+	if (!uasym_sig)
+		return;
+
+	kfree(uasym_sig->sig_data);
+	public_key_signature_free(uasym_sig->sig);
+	kfree(uasym_sig);
+}
+EXPORT_SYMBOL_GPL(uasym_sig_free_message);
diff --git a/include/crypto/uasym_keys_sigs.h b/include/crypto/uasym_keys_sigs.h
new file mode 100644
index 00000000000..ac5bce6d081
--- /dev/null
+++ b/include/crypto/uasym_keys_sigs.h
@@ -0,0 +1,72 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Header of the user asymmetric keys and signatures parser.
+ */
+
+#ifndef _CRYPTO_UASYM_KEYS_SIGS_H
+#define _CRYPTO_UASYM_KEYS_SIGS_H
+
+#include <linux/hash_info.h>
+#include <crypto/public_key.h>
+
+struct key;
+struct uasym_sig_message;
+
+#ifdef CONFIG_UASYM_KEYS_SIGS
+struct uasym_sig_message *uasym_sig_parse_message(const u8 *sig_data,
+						  size_t sig_len);
+int uasym_sig_supply_detached_data(struct uasym_sig_message *uasym_sig,
+				   const void *data, size_t data_len);
+int uasym_sig_get_content_data(struct uasym_sig_message *uasym_sig,
+			       const void **_data, size_t *_data_len,
+			       size_t *_headerlen);
+int uasym_sig_get_digest(struct uasym_sig_message *uasym_sig, const u8 **buf,
+			 u32 *len, enum hash_algo *hash_algo);
+int uasym_sig_verify_message(struct uasym_sig_message *uasym_sig,
+			     struct key *keyring);
+void uasym_sig_free_message(struct uasym_sig_message *uasym_sig);
+#else
+static inline struct uasym_sig_message *
+uasym_sig_parse_message(const u8 *sig_data, size_t sig_len)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline int
+uasym_sig_supply_detached_data(struct uasym_sig_message *uasym_sig,
+			       const void *data, size_t data_len)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int
+uasym_sig_get_content_data(struct uasym_sig_message *uasym_sig,
+			   const void **_data, size_t *_data_len,
+			   size_t *_headerlen)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int uasym_sig_get_digest(struct uasym_sig_message *uasym_sig,
+				       const u8 **buf, u32 *len,
+				       enum hash_algo *hash_algo)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int uasym_sig_verify_message(struct uasym_sig_message *uasym_sig,
+					   struct key *keyring)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void uasym_sig_free_message(struct uasym_sig_message *uasym_sig)
+{
+}
+
+#endif /* CONFIG_UASYM_KEYS_SIGS */
+#endif /* _CRYPTO_UASYM_KEYS_SIGS_H */
diff --git a/include/uapi/linux/uasym_parser.h b/include/uapi/linux/uasym_parser.h
index 25c2995b3d4..d1bc823d954 100644
--- a/include/uapi/linux/uasym_parser.h
+++ b/include/uapi/linux/uasym_parser.h
@@ -15,6 +15,7 @@ 
 
 #define FOR_EACH_DATA_TYPE(DATA_TYPE) \
 	DATA_TYPE(TYPE_KEY) \
+	DATA_TYPE(TYPE_SIG) \
 	DATA_TYPE(TYPE__LAST)
 
 #define FOR_EACH_FIELD(FIELD) \
@@ -24,6 +25,14 @@ 
 	FIELD(KEY_KID1) \
 	FIELD(KEY_KID2) \
 	FIELD(KEY_DESC) \
+	FIELD(SIG_S) \
+	FIELD(SIG_KEY_ALGO) \
+	FIELD(SIG_HASH_ALGO) \
+	FIELD(SIG_ENC) \
+	FIELD(SIG_KID0) \
+	FIELD(SIG_KID1) \
+	FIELD(SIG_KID2) \
+	FIELD(SIG_DATA_END) \
 	FIELD(FIELD__LAST)
 
 #define GENERATE_ENUM(ENUM) ENUM,