certs/system_keyring.c - linux - Git at Google

 /* System trusted keyring for trusted public keys
  *
  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public Licence
  * as published by the Free Software Foundation; either version
  * 2 of the Licence, or (at your option) any later version.
  */

 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/cred.h>
 #include <linux/err.h>
 #include <keys/asymmetric-type.h>
 #include <keys/system_keyring.h>
 #include <crypto/pkcs7.h>

 static struct key *builtin_trusted_keys;
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 static struct key *secondary_trusted_keys;
 #endif

 extern __initconst const u8 system_certificate_list[];
 extern __initconst const unsigned long system_certificate_list_size;

 /**
  * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
  *
  * Restrict the addition of keys into a keyring based on the key-to-be-added
  * being vouched for by a key in the built in system keyring.
  */
 int restrict_link_by_builtin_trusted(struct key *keyring,
 				     const struct key_type *type,
 				     const union key_payload *payload)
 {
 	return restrict_link_by_signature(builtin_trusted_keys, type, payload);
 }

 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 /**
  * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
  *   addition by both builtin and secondary keyrings
  *
  * Restrict the addition of keys into a keyring based on the key-to-be-added
  * being vouched for by a key in either the built-in or the secondary system
  * keyrings.
  */
 int restrict_link_by_builtin_and_secondary_trusted(
 	struct key *keyring,
 	const struct key_type *type,
 	const union key_payload *payload)
 {
 	/* If we have a secondary trusted keyring, then that contains a link
 	 * through to the builtin keyring and the search will follow that link.
 	 */
 	if (type == &key_type_keyring &&
 	    keyring == secondary_trusted_keys &&
 	    payload == &builtin_trusted_keys->payload)
 		/* Allow the builtin keyring to be added to the secondary */
 		return 0;

 	return restrict_link_by_signature(secondary_trusted_keys, type, payload);
 }
 #endif

 /*
  * Create the trusted keyrings
  */
 static __init int system_trusted_keyring_init(void)
 {
 	pr_notice("Initialise system trusted keyrings\n");

 	builtin_trusted_keys =
 		keyring_alloc(".builtin_trusted_keys",
 			      KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
 			      ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 			      KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
 			      KEY_ALLOC_NOT_IN_QUOTA,
 			      NULL, NULL);
 	if (IS_ERR(builtin_trusted_keys))
 		panic("Can't allocate builtin trusted keyring\n");

 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 	secondary_trusted_keys =
 		keyring_alloc(".secondary_trusted_keys",
 			      KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
 			      ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 			       KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
 			       KEY_USR_WRITE),
 			      KEY_ALLOC_NOT_IN_QUOTA,
 			      restrict_link_by_builtin_and_secondary_trusted,
 			      NULL);
 	if (IS_ERR(secondary_trusted_keys))
 		panic("Can't allocate secondary trusted keyring\n");

 	if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
 		panic("Can't link trusted keyrings\n");
 #endif

 	return 0;
 }

 /*
  * Must be initialised before we try and load the keys into the keyring.
  */
 device_initcall(system_trusted_keyring_init);

 /*
  * Load the compiled-in list of X.509 certificates.
  */
 static __init int load_system_certificate_list(void)
 {
 	key_ref_t key;
 	const u8 *p, *end;
 	size_t plen;

 	pr_notice("Loading compiled-in X.509 certificates\n");

 	p = system_certificate_list;
 	end = p + system_certificate_list_size;
 	while (p < end) {
 		/* Each cert begins with an ASN.1 SEQUENCE tag and must be more
 		 * than 256 bytes in size.
 		 */
 		if (end - p < 4)
 			goto dodgy_cert;
 		if (p[0] != 0x30 &&
 		    p[1] != 0x82)
 			goto dodgy_cert;
 		plen = (p[2] << 8) | p[3];
 		plen += 4;
 		if (plen > end - p)
 			goto dodgy_cert;

 		key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
 					   "asymmetric",
 					   NULL,
 					   p,
 					   plen,
 					   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 					   KEY_USR_VIEW | KEY_USR_READ),
 					   KEY_ALLOC_NOT_IN_QUOTA |
 					   KEY_ALLOC_BUILT_IN |
 					   KEY_ALLOC_BYPASS_RESTRICTION);
 		if (IS_ERR(key)) {
 			pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
 			       PTR_ERR(key));
 		} else {
 			pr_notice("Loaded X.509 cert '%s'\n",
 				  key_ref_to_ptr(key)->description);
 			key_ref_put(key);
 		}
 		p += plen;
 	}

 	return 0;

 dodgy_cert:
 	pr_err("Problem parsing in-kernel X.509 certificate list\n");
 	return 0;
 }
 late_initcall(load_system_certificate_list);

 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION

 /**
  * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
  * @data: The data to be verified (NULL if expecting internal data).
  * @len: Size of @data.
  * @raw_pkcs7: The PKCS#7 message that is the signature.
  * @pkcs7_len: The size of @raw_pkcs7.
  * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
  *					(void *)1UL for all trusted keys).
  * @usage: The use to which the key is being put.
  * @view_content: Callback to gain access to content.
  * @ctx: Context for callback.
  */
 int verify_pkcs7_signature(const void *data, size_t len,
 			   const void *raw_pkcs7, size_t pkcs7_len,
 			   struct key *trusted_keys,
 			   enum key_being_used_for usage,
 			   int (*view_content)(void *ctx,
 					       const void *data, size_t len,
 					       size_t asn1hdrlen),
 			   void *ctx)
 {
 	struct pkcs7_message *pkcs7;
 	int ret;

 	pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
 	if (IS_ERR(pkcs7))
 		return PTR_ERR(pkcs7);

 	/* The data should be detached - so we need to supply it. */
 	if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
 		pr_err("PKCS#7 signature with non-detached data\n");
 		ret = -EBADMSG;
 		goto error;
 	}

 	ret = pkcs7_verify(pkcs7, usage);
 	if (ret < 0)
 		goto error;

 	if (!trusted_keys) {
 		trusted_keys = builtin_trusted_keys;
 	} else if (trusted_keys == (void *)1UL) {
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 		trusted_keys = secondary_trusted_keys;
 #else
 		trusted_keys = builtin_trusted_keys;
 #endif
 	}
 	ret = pkcs7_validate_trust(pkcs7, trusted_keys);
 	if (ret < 0) {
 		if (ret == -ENOKEY)
 			pr_err("PKCS#7 signature not signed with a trusted key\n");
 		goto error;
 	}

 	if (view_content) {
 		size_t asn1hdrlen;

 		ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
 		if (ret < 0) {
 			if (ret == -ENODATA)
 				pr_devel("PKCS#7 message does not contain data\n");
 			goto error;
 		}

 		ret = view_content(ctx, data, len, asn1hdrlen);
 	}

 error:
 	pkcs7_free_message(pkcs7);
 	pr_devel("<==%s() = %d\n", __func__, ret);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(verify_pkcs7_signature);

 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
	/* System trusted keyring for trusted public keys
	*
	* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public Licence
	* as published by the Free Software Foundation; either version
	* 2 of the Licence, or (at your option) any later version.
	*/

	#include <linux/export.h>
	#include <linux/kernel.h>
	#include <linux/sched.h>
	#include <linux/cred.h>
	#include <linux/err.h>
	#include <keys/asymmetric-type.h>
	#include <keys/system_keyring.h>
	#include <crypto/pkcs7.h>

	static struct key *builtin_trusted_keys;
	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	static struct key *secondary_trusted_keys;
	#endif

	extern __initconst const u8 system_certificate_list[];
	extern __initconst const unsigned long system_certificate_list_size;

	/**
	* restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
	*
	* Restrict the addition of keys into a keyring based on the key-to-be-added
	* being vouched for by a key in the built in system keyring.
	*/
	int restrict_link_by_builtin_trusted(struct key *keyring,
	const struct key_type *type,
	const union key_payload *payload)
	{
	return restrict_link_by_signature(builtin_trusted_keys, type, payload);
	}

	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	/**
	* restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
	* addition by both builtin and secondary keyrings
	*
	* Restrict the addition of keys into a keyring based on the key-to-be-added
	* being vouched for by a key in either the built-in or the secondary system
	* keyrings.
	*/
	int restrict_link_by_builtin_and_secondary_trusted(
	struct key *keyring,
	const struct key_type *type,
	const union key_payload *payload)
	{
	/* If we have a secondary trusted keyring, then that contains a link
	* through to the builtin keyring and the search will follow that link.
	*/
	if (type == &key_type_keyring &&
	keyring == secondary_trusted_keys &&
	payload == &builtin_trusted_keys->payload)
	/* Allow the builtin keyring to be added to the secondary */
	return 0;

	return restrict_link_by_signature(secondary_trusted_keys, type, payload);
	}
	#endif

	/*
	* Create the trusted keyrings
	*/
	static __init int system_trusted_keyring_init(void)
	{
	pr_notice("Initialise system trusted keyrings\n");

	builtin_trusted_keys =
	keyring_alloc(".builtin_trusted_keys",
	KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
	((KEY_POS_ALL & ~KEY_POS_SETATTR) \|
	KEY_USR_VIEW \| KEY_USR_READ \| KEY_USR_SEARCH),
	KEY_ALLOC_NOT_IN_QUOTA,
	NULL, NULL);
	if (IS_ERR(builtin_trusted_keys))
	panic("Can't allocate builtin trusted keyring\n");

	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	secondary_trusted_keys =
	keyring_alloc(".secondary_trusted_keys",
	KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
	((KEY_POS_ALL & ~KEY_POS_SETATTR) \|
	KEY_USR_VIEW \| KEY_USR_READ \| KEY_USR_SEARCH \|
	KEY_USR_WRITE),
	KEY_ALLOC_NOT_IN_QUOTA,
	restrict_link_by_builtin_and_secondary_trusted,
	NULL);
	if (IS_ERR(secondary_trusted_keys))
	panic("Can't allocate secondary trusted keyring\n");

	if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
	panic("Can't link trusted keyrings\n");
	#endif

	return 0;
	}

	/*
	* Must be initialised before we try and load the keys into the keyring.
	*/
	device_initcall(system_trusted_keyring_init);

	/*
	* Load the compiled-in list of X.509 certificates.
	*/
	static __init int load_system_certificate_list(void)
	{
	key_ref_t key;
	const u8 p, end;
	size_t plen;

	pr_notice("Loading compiled-in X.509 certificates\n");

	p = system_certificate_list;
	end = p + system_certificate_list_size;
	while (p < end) {
	/* Each cert begins with an ASN.1 SEQUENCE tag and must be more
	* than 256 bytes in size.
	*/
	if (end - p < 4)
	goto dodgy_cert;
	if (p[0] != 0x30 &&
	p[1] != 0x82)
	goto dodgy_cert;
	plen = (p[2] << 8) \| p[3];
	plen += 4;
	if (plen > end - p)
	goto dodgy_cert;

	key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
	"asymmetric",
	NULL,
	p,
	plen,
	((KEY_POS_ALL & ~KEY_POS_SETATTR) \|
	KEY_USR_VIEW \| KEY_USR_READ),
	KEY_ALLOC_NOT_IN_QUOTA \|
	KEY_ALLOC_BUILT_IN \|
	KEY_ALLOC_BYPASS_RESTRICTION);
	if (IS_ERR(key)) {
	pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
	PTR_ERR(key));
	} else {
	pr_notice("Loaded X.509 cert '%s'\n",
	key_ref_to_ptr(key)->description);
	key_ref_put(key);
	}
	p += plen;
	}

	return 0;

	dodgy_cert:
	pr_err("Problem parsing in-kernel X.509 certificate list\n");
	return 0;
	}
	late_initcall(load_system_certificate_list);

	#ifdef CONFIG_SYSTEM_DATA_VERIFICATION

	/**
	* verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
	* @data: The data to be verified (NULL if expecting internal data).
	* @len: Size of @data.
	* @raw_pkcs7: The PKCS#7 message that is the signature.
	* @pkcs7_len: The size of @raw_pkcs7.
	* @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
	* (void *)1UL for all trusted keys).
	* @usage: The use to which the key is being put.
	* @view_content: Callback to gain access to content.
	* @ctx: Context for callback.
	*/
	int verify_pkcs7_signature(const void *data, size_t len,
	const void *raw_pkcs7, size_t pkcs7_len,
	struct key *trusted_keys,
	enum key_being_used_for usage,
	int (view_content)(void ctx,
	const void *data, size_t len,
	size_t asn1hdrlen),
	void *ctx)
	{
	struct pkcs7_message *pkcs7;
	int ret;

	pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
	if (IS_ERR(pkcs7))
	return PTR_ERR(pkcs7);

	/* The data should be detached - so we need to supply it. */
	if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
	pr_err("PKCS#7 signature with non-detached data\n");
	ret = -EBADMSG;
	goto error;
	}

	ret = pkcs7_verify(pkcs7, usage);
	if (ret < 0)
	goto error;

	if (!trusted_keys) {
	trusted_keys = builtin_trusted_keys;
	} else if (trusted_keys == (void *)1UL) {
	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	trusted_keys = secondary_trusted_keys;
	#else
	trusted_keys = builtin_trusted_keys;
	#endif
	}
	ret = pkcs7_validate_trust(pkcs7, trusted_keys);
	if (ret < 0) {
	if (ret == -ENOKEY)
	pr_err("PKCS#7 signature not signed with a trusted key\n");
	goto error;
	}

	if (view_content) {
	size_t asn1hdrlen;

	ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
	if (ret < 0) {
	if (ret == -ENODATA)
	pr_devel("PKCS#7 message does not contain data\n");
	goto error;
	}

	ret = view_content(ctx, data, len, asn1hdrlen);
	}

	error:
	pkcs7_free_message(pkcs7);
	pr_devel("<==%s() = %d\n", __func__, ret);
	return ret;
	}
	EXPORT_SYMBOL_GPL(verify_pkcs7_signature);

	#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */