[linux.git] / security / keys / permission.c

/* Key permission checking
 *
 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/security.h>
#include "internal.h"

/**
 * key_task_permission - Check a key can be used
 * @key_ref: The key to check.
 * @cred: The credentials to use.
 * @perm: The permissions to check for.
 *
 * Check to see whether permission is granted to use a key in the desired way,
 * but permit the security modules to override.
 *
 * The caller must hold either a ref on cred or must hold the RCU readlock.
 *
 * Returns 0 if successful, -EACCES if access is denied based on the
 * permissions bits or the LSM check.
 */
int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
			unsigned perm)
{
	struct key *key;
	key_perm_t kperm;
	int ret;

	key = key_ref_to_ptr(key_ref);

	/* use the second 8-bits of permissions for keys the caller owns */
	if (uid_eq(key->uid, cred->fsuid)) {
		kperm = key->perm >> 16;
		goto use_these_perms;
	}

	/* use the third 8-bits of permissions for keys the caller has a group
	 * membership in common with */
	if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) {
		if (gid_eq(key->gid, cred->fsgid)) {
			kperm = key->perm >> 8;
			goto use_these_perms;
		}

		ret = groups_search(cred->group_info, key->gid);
		if (ret) {
			kperm = key->perm >> 8;
			goto use_these_perms;
		}
	}

	/* otherwise use the least-significant 8-bits */
	kperm = key->perm;

use_these_perms:

	/* use the top 8-bits of permissions for keys the caller possesses
	 * - possessor permissions are additive with other permissions
	 */
	if (is_key_possessed(key_ref))
		kperm |= key->perm >> 24;

	kperm = kperm & perm & KEY_NEED_ALL;

	if (kperm != perm)
		return -EACCES;

	/* let LSM be the final arbiter */
	return security_key_permission(key_ref, cred, perm);
}
EXPORT_SYMBOL(key_task_permission);

/**
 * key_validate - Validate a key.
 * @key: The key to be validated.
 *
 * Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the
 * key is invalidated, -EKEYREVOKED if the key's type has been removed or if
 * the key has been revoked or -EKEYEXPIRED if the key has expired.
 */
int key_validate(const struct key *key)
{
	unsigned long flags = key->flags;

	if (flags & (1 << KEY_FLAG_INVALIDATED))
		return -ENOKEY;

	/* check it's still accessible */
	if (flags & ((1 << KEY_FLAG_REVOKED) |
		     (1 << KEY_FLAG_DEAD)))
		return -EKEYREVOKED;

	/* check it hasn't expired */
	if (key->expiry) {
		struct timespec now = current_kernel_time();
		if (now.tv_sec >= key->expiry)
			return -EKEYEXPIRED;
	}

	return 0;
}
EXPORT_SYMBOL(key_validate);
Commit	Line	Data
973c9f4f	1	/* Key permission checking
468ed2b0 DH	2	*
	3	* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells ([email protected])
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/module.h>
29db9190	13	#include <linux/security.h>
468ed2b0 DH	14	#include "internal.h"
468ed2b0 DH	15
d84f4f99 DH	16	/**
d84f4f99 DH	17	* key_task_permission - Check a key can be used
973c9f4f DH	18	* @key_ref: The key to check.
	19	* @cred: The credentials to use.
	20	* @perm: The permissions to check for.
d84f4f99 DH	21	*
	22	* Check to see whether permission is granted to use a key in the desired way,
	23	* but permit the security modules to override.
	24	*
973c9f4f DH	25	* The caller must hold either a ref on cred or must hold the RCU readlock.
	26	*
	27	* Returns 0 if successful, -EACCES if access is denied based on the
	28	* permissions bits or the LSM check.
468ed2b0	29	*/
d84f4f99	30	int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
f5895943	31	unsigned perm)
468ed2b0 DH	32	{
	33	struct key *key;
	34	key_perm_t kperm;
	35	int ret;
	36
	37	key = key_ref_to_ptr(key_ref);
	38
468ed2b0	39	/* use the second 8-bits of permissions for keys the caller owns */
9a56c2db	40	if (uid_eq(key->uid, cred->fsuid)) {
468ed2b0 DH	41	kperm = key->perm >> 16;
	42	goto use_these_perms;
	43	}
	44
	45	/* use the third 8-bits of permissions for keys the caller has a group
	46	* membership in common with */
9a56c2db EB	47	if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) {
9a56c2db EB	48	if (gid_eq(key->gid, cred->fsgid)) {
468ed2b0 DH	49	kperm = key->perm >> 8;
	50	goto use_these_perms;
	51	}
	52
9a56c2db	53	ret = groups_search(cred->group_info, key->gid);
468ed2b0 DH	54	if (ret) {
	55	kperm = key->perm >> 8;
	56	goto use_these_perms;
	57	}
	58	}
	59
	60	/* otherwise use the least-significant 8-bits */
	61	kperm = key->perm;
	62
	63	use_these_perms:
c69e8d9c	64
7ab501db DH	65	/* use the top 8-bits of permissions for keys the caller possesses
	66	* - possessor permissions are additive with other permissions
	67	*/
	68	if (is_key_possessed(key_ref))
	69	kperm \|= key->perm >> 24;
	70
f5895943	71	kperm = kperm & perm & KEY_NEED_ALL;
468ed2b0	72
29db9190 DH	73	if (kperm != perm)
	74	return -EACCES;
	75
	76	/* let LSM be the final arbiter */
d84f4f99	77	return security_key_permission(key_ref, cred, perm);
a8b17ed0	78	}
468ed2b0	79	EXPORT_SYMBOL(key_task_permission);
b5f545c8	80
973c9f4f DH	81	/**
	82	* key_validate - Validate a key.
	83	* @key: The key to be validated.
	84	*
fd75815f DH	85	* Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the
	86	* key is invalidated, -EKEYREVOKED if the key's type has been removed or if
	87	* the key has been revoked or -EKEYEXPIRED if the key has expired.
b5f545c8	88	*/
b404aef7	89	int key_validate(const struct key *key)
b5f545c8	90	{
fd75815f	91	unsigned long flags = key->flags;
b404aef7 DH	92
	93	if (flags & (1 << KEY_FLAG_INVALIDATED))
	94	return -ENOKEY;
	95
	96	/* check it's still accessible */
	97	if (flags & ((1 << KEY_FLAG_REVOKED) \|
	98	(1 << KEY_FLAG_DEAD)))
	99	return -EKEYREVOKED;
	100
	101	/* check it hasn't expired */
	102	if (key->expiry) {
	103	struct timespec now = current_kernel_time();
	104	if (now.tv_sec >= key->expiry)
	105	return -EKEYEXPIRED;
b5f545c8 DH	106	}
b5f545c8 DH	107
b404aef7	108	return 0;
a8b17ed0	109	}
b5f545c8	110	EXPORT_SYMBOL(key_validate);