// SPDX-License-Identifier: GPL-2.0-or-later

  /* Asymmetric public-key cryptography key type
   *

   * See Documentation/crypto/asymmetric-keys.rst

   *
   * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)

   */
  #include <keys/asymmetric-subtype.h>

  #include <keys/asymmetric-parser.h>

  #include <crypto/public_key.h>

  #include <linux/seq_file.h>
  #include <linux/module.h>
  #include <linux/slab.h>

  #include <linux/ctype.h>

  #include <keys/system_keyring.h>

  #include <keys/user-type.h>

  #include "asymmetric_keys.h"
  
  MODULE_LICENSE("GPL");

  const char *const key_being_used_for[NR__KEY_BEING_USED_FOR] = {
  	[VERIFYING_MODULE_SIGNATURE]		= "mod sig",
  	[VERIFYING_FIRMWARE_SIGNATURE]		= "firmware sig",
  	[VERIFYING_KEXEC_PE_SIGNATURE]		= "kexec PE sig",
  	[VERIFYING_KEY_SIGNATURE]		= "key sig",
  	[VERIFYING_KEY_SELF_SIGNATURE]		= "key self sig",
  	[VERIFYING_UNSPECIFIED_SIGNATURE]	= "unspec sig",
  };
  EXPORT_SYMBOL_GPL(key_being_used_for);

  static LIST_HEAD(asymmetric_key_parsers);
  static DECLARE_RWSEM(asymmetric_key_parsers_sem);

  /**

   * find_asymmetric_key - Find a key by ID.

   * @keyring: The keys to search.

   * @id_0: The first ID to look for or NULL.
   * @id_1: The second ID to look for or NULL.

   * @partial: Use partial match if true, exact if false.
   *
   * Find a key in the given keyring by identifier.  The preferred identifier is

   * the id_0 and the fallback identifier is the id_1.  If both are given, the
   * lookup is by the former, but the latter must also match.

   */

  struct key *find_asymmetric_key(struct key *keyring,
  				const struct asymmetric_key_id *id_0,
  				const struct asymmetric_key_id *id_1,
  				bool partial)

  {
  	struct key *key;
  	key_ref_t ref;
  	const char *lookup;
  	char *req, *p;
  	int len;

  	BUG_ON(!id_0 && !id_1);

  	if (id_0) {
  		lookup = id_0->data;
  		len = id_0->len;

  	} else {

  		lookup = id_1->data;
  		len = id_1->len;

  	}
  
  	/* Construct an identifier "id:<keyid>". */
  	p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
  	if (!req)
  		return ERR_PTR(-ENOMEM);
  
  	if (partial) {
  		*p++ = 'i';
  		*p++ = 'd';
  	} else {
  		*p++ = 'e';
  		*p++ = 'x';
  	}
  	*p++ = ':';
  	p = bin2hex(p, lookup, len);
  	*p = 0;
  
  	pr_debug("Look up: \"%s\"
  ", req);
  
  	ref = keyring_search(make_key_ref(keyring, 1),

  			     &key_type_asymmetric, req, true);

  	if (IS_ERR(ref))
  		pr_debug("Request for key '%s' err %ld
  ", req, PTR_ERR(ref));
  	kfree(req);
  
  	if (IS_ERR(ref)) {
  		switch (PTR_ERR(ref)) {
  			/* Hide some search errors */
  		case -EACCES:
  		case -ENOTDIR:
  		case -EAGAIN:
  			return ERR_PTR(-ENOKEY);
  		default:
  			return ERR_CAST(ref);
  		}
  	}
  
  	key = key_ref_to_ptr(ref);

  	if (id_0 && id_1) {

  		const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);

  		if (!kids->id[1]) {

  			pr_debug("First ID matches, but second is missing
  ");

  			goto reject;
  		}

  		if (!asymmetric_key_id_same(id_1, kids->id[1])) {
  			pr_debug("First ID matches, but second does not
  ");

  			goto reject;
  		}
  	}
  
  	pr_devel("<==%s() = 0 [%x]
  ", __func__, key_serial(key));
  	return key;
  
  reject:
  	key_put(key);
  	return ERR_PTR(-EKEYREJECTED);
  }

  EXPORT_SYMBOL_GPL(find_asymmetric_key);

  
  /**

   * asymmetric_key_generate_id: Construct an asymmetric key ID
   * @val_1: First binary blob
   * @len_1: Length of first binary blob
   * @val_2: Second binary blob
   * @len_2: Length of second binary blob
   *
   * Construct an asymmetric key ID from a pair of binary blobs.
   */
  struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
  						     size_t len_1,
  						     const void *val_2,
  						     size_t len_2)
  {
  	struct asymmetric_key_id *kid;
  
  	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
  		      GFP_KERNEL);
  	if (!kid)
  		return ERR_PTR(-ENOMEM);
  	kid->len = len_1 + len_2;
  	memcpy(kid->data, val_1, len_1);
  	memcpy(kid->data + len_1, val_2, len_2);
  	return kid;
  }
  EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
  
  /**
   * asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.

   * @kid1: The key ID to compare
   * @kid2: The key ID to compare

   */
  bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
  			    const struct asymmetric_key_id *kid2)
  {
  	if (!kid1 || !kid2)
  		return false;
  	if (kid1->len != kid2->len)
  		return false;
  	return memcmp(kid1->data, kid2->data, kid1->len) == 0;
  }
  EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
  
  /**

   * asymmetric_key_id_partial - Return true if two asymmetric keys IDs
   * partially match

   * @kid1: The key ID to compare
   * @kid2: The key ID to compare

   */
  bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
  			       const struct asymmetric_key_id *kid2)
  {
  	if (!kid1 || !kid2)
  		return false;
  	if (kid1->len < kid2->len)
  		return false;
  	return memcmp(kid1->data + (kid1->len - kid2->len),
  		      kid2->data, kid2->len) == 0;
  }
  EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
  
  /**

   * asymmetric_match_key_ids - Search asymmetric key IDs
   * @kids: The list of key IDs to check
   * @match_id: The key ID we're looking for

   * @match: The match function to use

   */

  static bool asymmetric_match_key_ids(
  	const struct asymmetric_key_ids *kids,
  	const struct asymmetric_key_id *match_id,
  	bool (*match)(const struct asymmetric_key_id *kid1,
  		      const struct asymmetric_key_id *kid2))

  {

  	int i;

  	if (!kids || !match_id)
  		return false;

  	for (i = 0; i < ARRAY_SIZE(kids->id); i++)
  		if (match(kids->id[i], match_id))
  			return true;

  	return false;
  }

  /* helper function can be called directly with pre-allocated memory */
  inline int __asymmetric_key_hex_to_key_id(const char *id,
  				   struct asymmetric_key_id *match_id,
  				   size_t hexlen)
  {
  	match_id->len = hexlen;
  	return hex2bin(match_id->data, id, hexlen);
  }

  /**
   * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
   * @id: The ID as a hex string.
   */
  struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
  {
  	struct asymmetric_key_id *match_id;

  	size_t asciihexlen;

  	int ret;

  
  	if (!*id)
  		return ERR_PTR(-EINVAL);

  	asciihexlen = strlen(id);
  	if (asciihexlen & 1)

  		return ERR_PTR(-EINVAL);

  	match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,

  			   GFP_KERNEL);
  	if (!match_id)
  		return ERR_PTR(-ENOMEM);

  	ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);

  	if (ret < 0) {
  		kfree(match_id);
  		return ERR_PTR(-EINVAL);
  	}

  	return match_id;
  }

  /*

   * Match asymmetric keys by an exact match on an ID.

   */

  static bool asymmetric_key_cmp(const struct key *key,
  			       const struct key_match_data *match_data)

  {

  	const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
  	const struct asymmetric_key_id *match_id = match_data->preparsed;

  	return asymmetric_match_key_ids(kids, match_id,
  					asymmetric_key_id_same);
  }
  
  /*
   * Match asymmetric keys by a partial match on an IDs.
   */
  static bool asymmetric_key_cmp_partial(const struct key *key,
  				       const struct key_match_data *match_data)
  {
  	const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
  	const struct asymmetric_key_id *match_id = match_data->preparsed;
  
  	return asymmetric_match_key_ids(kids, match_id,
  					asymmetric_key_id_partial);

  }
  
  /*

   * Preparse the match criterion.  If we don't set lookup_type and cmp,
   * the default will be an exact match on the key description.
   *
   * There are some specifiers for matching key IDs rather than by the key
   * description:
   *

   *	"id:<id>" - find a key by partial match on any available ID
   *	"ex:<id>" - find a key by exact match on any available ID

   *
   * These have to be searched by iteration rather than by direct lookup because
   * the key is hashed according to its description.
   */
  static int asymmetric_key_match_preparse(struct key_match_data *match_data)
  {

  	struct asymmetric_key_id *match_id;
  	const char *spec = match_data->raw_data;
  	const char *id;

  	bool (*cmp)(const struct key *, const struct key_match_data *) =
  		asymmetric_key_cmp;

  
  	if (!spec || !*spec)
  		return -EINVAL;
  	if (spec[0] == 'i' &&
  	    spec[1] == 'd' &&
  	    spec[2] == ':') {
  		id = spec + 3;

  		cmp = asymmetric_key_cmp_partial;
  	} else if (spec[0] == 'e' &&
  		   spec[1] == 'x' &&
  		   spec[2] == ':') {
  		id = spec + 3;

  	} else {
  		goto default_match;
  	}
  
  	match_id = asymmetric_key_hex_to_key_id(id);

  	if (IS_ERR(match_id))
  		return PTR_ERR(match_id);

  
  	match_data->preparsed = match_id;

  	match_data->cmp = cmp;

  	match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
  	return 0;
  
  default_match:

  	return 0;
  }
  
  /*
   * Free the preparsed the match criterion.
   */
  static void asymmetric_key_match_free(struct key_match_data *match_data)
  {

  	kfree(match_data->preparsed);

  }
  
  /*

   * Describe the asymmetric key
   */
  static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
  {
  	const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);

  	const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
  	const struct asymmetric_key_id *kid;
  	const unsigned char *p;
  	int n;

  
  	seq_puts(m, key->description);
  
  	if (subtype) {
  		seq_puts(m, ": ");
  		subtype->describe(key, m);

  		if (kids && kids->id[1]) {
  			kid = kids->id[1];

  			seq_putc(m, ' ');

  			n = kid->len;
  			p = kid->data;

  			if (n > 4) {
  				p += n - 4;
  				n = 4;

  			}
  			seq_printf(m, "%*phN", n, p);

  		}
  
  		seq_puts(m, " [");
  		/* put something here to indicate the key's capabilities */
  		seq_putc(m, ']');
  	}
  }
  
  /*

   * Preparse a asymmetric payload to get format the contents appropriately for the
   * internal payload to cut down on the number of scans of the data performed.
   *
   * We also generate a proposed description from the contents of the key that
   * can be used to name the key if the user doesn't want to provide one.
   */
  static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
  {
  	struct asymmetric_key_parser *parser;
  	int ret;
  
  	pr_devel("==>%s()
  ", __func__);
  
  	if (prep->datalen == 0)
  		return -EINVAL;
  
  	down_read(&asymmetric_key_parsers_sem);
  
  	ret = -EBADMSG;
  	list_for_each_entry(parser, &asymmetric_key_parsers, link) {
  		pr_debug("Trying parser '%s'
  ", parser->name);
  
  		ret = parser->parse(prep);
  		if (ret != -EBADMSG) {
  			pr_debug("Parser recognised the format (ret %d)
  ",
  				 ret);
  			break;
  		}
  	}
  
  	up_read(&asymmetric_key_parsers_sem);
  	pr_devel("<==%s() = %d
  ", __func__, ret);
  	return ret;
  }
  
  /*

   * Clean up the key ID list
   */
  static void asymmetric_key_free_kids(struct asymmetric_key_ids *kids)
  {
  	int i;
  
  	if (kids) {
  		for (i = 0; i < ARRAY_SIZE(kids->id); i++)
  			kfree(kids->id[i]);
  		kfree(kids);
  	}
  }
  
  /*

   * Clean up the preparse data
   */
  static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
  {

  	struct asymmetric_key_subtype *subtype = prep->payload.data[asym_subtype];
  	struct asymmetric_key_ids *kids = prep->payload.data[asym_key_ids];

  
  	pr_devel("==>%s()
  ", __func__);
  
  	if (subtype) {

  		subtype->destroy(prep->payload.data[asym_crypto],
  				 prep->payload.data[asym_auth]);

  		module_put(subtype->owner);
  	}

  	asymmetric_key_free_kids(kids);

  	kfree(prep->description);
  }
  
  /*

   * dispose of the data dangling from the corpse of a asymmetric key
   */
  static void asymmetric_key_destroy(struct key *key)
  {
  	struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);

  	struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
  	void *data = key->payload.data[asym_crypto];

  	void *auth = key->payload.data[asym_auth];

  
  	key->payload.data[asym_crypto] = NULL;
  	key->payload.data[asym_subtype] = NULL;
  	key->payload.data[asym_key_ids] = NULL;

  	key->payload.data[asym_auth] = NULL;

  	if (subtype) {

  		subtype->destroy(data, auth);

  		module_put(subtype->owner);

  	}

  	asymmetric_key_free_kids(kids);

  }

  static struct key_restriction *asymmetric_restriction_alloc(
  	key_restrict_link_func_t check,
  	struct key *key)
  {
  	struct key_restriction *keyres =
  		kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
  
  	if (!keyres)
  		return ERR_PTR(-ENOMEM);
  
  	keyres->check = check;
  	keyres->key = key;
  	keyres->keytype = &key_type_asymmetric;
  
  	return keyres;
  }
  
  /*
   * look up keyring restrict functions for asymmetric keys
   */
  static struct key_restriction *asymmetric_lookup_restriction(
  	const char *restriction)
  {

  	char *restrict_method;
  	char *parse_buf;
  	char *next;
  	struct key_restriction *ret = ERR_PTR(-EINVAL);

  	if (strcmp("builtin_trusted", restriction) == 0)
  		return asymmetric_restriction_alloc(
  			restrict_link_by_builtin_trusted, NULL);
  
  	if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
  		return asymmetric_restriction_alloc(
  			restrict_link_by_builtin_and_secondary_trusted, NULL);

  	parse_buf = kstrndup(restriction, PAGE_SIZE, GFP_KERNEL);
  	if (!parse_buf)
  		return ERR_PTR(-ENOMEM);
  
  	next = parse_buf;
  	restrict_method = strsep(&next, ":");
  
  	if ((strcmp(restrict_method, "key_or_keyring") == 0) && next) {

  		char *key_text;

  		key_serial_t serial;
  		struct key *key;

  		key_restrict_link_func_t link_fn =
  			restrict_link_by_key_or_keyring;
  		bool allow_null_key = false;

  		key_text = strsep(&next, ":");
  
  		if (next) {
  			if (strcmp(next, "chain") != 0)
  				goto out;
  
  			link_fn = restrict_link_by_key_or_keyring_chain;
  			allow_null_key = true;
  		}

  		if (kstrtos32(key_text, 0, &serial) < 0)

  			goto out;

  
  		if ((serial == 0) && allow_null_key) {
  			key = NULL;
  		} else {
  			key = key_lookup(serial);
  			if (IS_ERR(key)) {
  				ret = ERR_CAST(key);
  				goto out;
  			}

  		}

  		ret = asymmetric_restriction_alloc(link_fn, key);

  		if (IS_ERR(ret))
  			key_put(key);
  	}
  
  out:
  	kfree(parse_buf);
  	return ret;

  }

  int asymmetric_key_eds_op(struct kernel_pkey_params *params,
  			  const void *in, void *out)
  {
  	const struct asymmetric_key_subtype *subtype;
  	struct key *key = params->key;
  	int ret;
  
  	pr_devel("==>%s()
  ", __func__);
  
  	if (key->type != &key_type_asymmetric)
  		return -EINVAL;
  	subtype = asymmetric_key_subtype(key);
  	if (!subtype ||
  	    !key->payload.data[0])
  		return -EINVAL;
  	if (!subtype->eds_op)
  		return -ENOTSUPP;
  
  	ret = subtype->eds_op(params, in, out);
  
  	pr_devel("<==%s() = %d
  ", __func__, ret);
  	return ret;
  }
  
  static int asymmetric_key_verify_signature(struct kernel_pkey_params *params,
  					   const void *in, const void *in2)
  {
  	struct public_key_signature sig = {
  		.s_size		= params->in2_len,
  		.digest_size	= params->in_len,
  		.encoding	= params->encoding,
  		.hash_algo	= params->hash_algo,
  		.digest		= (void *)in,
  		.s		= (void *)in2,
  	};
  
  	return verify_signature(params->key, &sig);
  }

  struct key_type key_type_asymmetric = {

  	.name			= "asymmetric",
  	.preparse		= asymmetric_key_preparse,
  	.free_preparse		= asymmetric_key_free_preparse,
  	.instantiate		= generic_key_instantiate,
  	.match_preparse		= asymmetric_key_match_preparse,
  	.match_free		= asymmetric_key_match_free,
  	.destroy		= asymmetric_key_destroy,
  	.describe		= asymmetric_key_describe,
  	.lookup_restriction	= asymmetric_lookup_restriction,

  	.asym_query		= query_asymmetric_key,
  	.asym_eds_op		= asymmetric_key_eds_op,
  	.asym_verify_signature	= asymmetric_key_verify_signature,

  };
  EXPORT_SYMBOL_GPL(key_type_asymmetric);

  /**
   * register_asymmetric_key_parser - Register a asymmetric key blob parser
   * @parser: The parser to register
   */
  int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
  {
  	struct asymmetric_key_parser *cursor;
  	int ret;
  
  	down_write(&asymmetric_key_parsers_sem);
  
  	list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
  		if (strcmp(cursor->name, parser->name) == 0) {
  			pr_err("Asymmetric key parser '%s' already registered
  ",
  			       parser->name);
  			ret = -EEXIST;
  			goto out;
  		}
  	}
  
  	list_add_tail(&parser->link, &asymmetric_key_parsers);
  
  	pr_notice("Asymmetric key parser '%s' registered
  ", parser->name);
  	ret = 0;
  
  out:
  	up_write(&asymmetric_key_parsers_sem);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
  
  /**
   * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
   * @parser: The parser to unregister
   */
  void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
  {
  	down_write(&asymmetric_key_parsers_sem);
  	list_del(&parser->link);
  	up_write(&asymmetric_key_parsers_sem);
  
  	pr_notice("Asymmetric key parser '%s' unregistered
  ", parser->name);
  }
  EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);

  /*
   * Module stuff
   */
  static int __init asymmetric_key_init(void)
  {
  	return register_key_type(&key_type_asymmetric);
  }
  
  static void __exit asymmetric_key_cleanup(void)
  {
  	unregister_key_type(&key_type_asymmetric);
  }
  
  module_init(asymmetric_key_init);
  module_exit(asymmetric_key_cleanup);