[linux-2.6-block.git] / fs / afs / security.c

/* AFS security handling
 *
 * Copyright (C) 2007, 2017 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 License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/sched.h>
#include <linux/hashtable.h>
#include <keys/rxrpc-type.h>
#include "internal.h"

static DEFINE_HASHTABLE(afs_permits_cache, 10);
static DEFINE_SPINLOCK(afs_permits_lock);

/*
 * get a key
 */
struct key *afs_request_key(struct afs_cell *cell)
{
	struct key *key;

	_enter("{%x}", key_serial(cell->anonymous_key));

	_debug("key %s", cell->anonymous_key->description);
	key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
			  NULL);
	if (IS_ERR(key)) {
		if (PTR_ERR(key) != -ENOKEY) {
			_leave(" = %ld", PTR_ERR(key));
			return key;
		}

		/* act as anonymous user */
		_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
		return key_get(cell->anonymous_key);
	} else {
		/* act as authorised user */
		_leave(" = {%x} [auth]", key_serial(key));
		return key;
	}
}

/*
 * Dispose of a list of permits.
 */
static void afs_permits_rcu(struct rcu_head *rcu)
{
	struct afs_permits *permits =
		container_of(rcu, struct afs_permits, rcu);
	int i;

	for (i = 0; i < permits->nr_permits; i++)
		key_put(permits->permits[i].key);
	kfree(permits);
}

/*
 * Discard a permission cache.
 */
void afs_put_permits(struct afs_permits *permits)
{
	if (permits && refcount_dec_and_test(&permits->usage)) {
		spin_lock(&afs_permits_lock);
		hash_del_rcu(&permits->hash_node);
		spin_unlock(&afs_permits_lock);
		call_rcu(&permits->rcu, afs_permits_rcu);
	}
}

/*
 * Clear a permit cache on callback break.
 */
void afs_clear_permits(struct afs_vnode *vnode)
{
	struct afs_permits *permits;

	spin_lock(&vnode->lock);
	permits = rcu_dereference_protected(vnode->permit_cache,
					    lockdep_is_held(&vnode->lock));
	RCU_INIT_POINTER(vnode->permit_cache, NULL);
	vnode->cb_break++;
	spin_unlock(&vnode->lock);

	if (permits)
		afs_put_permits(permits);
}

/*
 * Hash a list of permits.  Use simple addition to make it easy to add an extra
 * one at an as-yet indeterminate position in the list.
 */
static void afs_hash_permits(struct afs_permits *permits)
{
	unsigned long h = permits->nr_permits;
	int i;

	for (i = 0; i < permits->nr_permits; i++) {
		h += (unsigned long)permits->permits[i].key / sizeof(void *);
		h += permits->permits[i].access;
	}

	permits->h = h;
}

/*
 * Cache the CallerAccess result obtained from doing a fileserver operation
 * that returned a vnode status for a particular key.  If a callback break
 * occurs whilst the operation was in progress then we have to ditch the cache
 * as the ACL *may* have changed.
 */
void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
		      unsigned int cb_break)
{
	struct afs_permits *permits, *xpermits, *replacement, *zap, *new = NULL;
	afs_access_t caller_access = READ_ONCE(vnode->status.caller_access);
	size_t size = 0;
	bool changed = false;
	int i, j;

	_enter("{%llx:%llu},%x,%x",
	       vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);

	rcu_read_lock();

	/* Check for the common case first: We got back the same access as last
	 * time we tried and already have it recorded.
	 */
	permits = rcu_dereference(vnode->permit_cache);
	if (permits) {
		if (!permits->invalidated) {
			for (i = 0; i < permits->nr_permits; i++) {
				if (permits->permits[i].key < key)
					continue;
				if (permits->permits[i].key > key)
					break;
				if (permits->permits[i].access != caller_access) {
					changed = true;
					break;
				}

				if (afs_cb_is_broken(cb_break, vnode,
						     vnode->cb_interest)) {
					changed = true;
					break;
				}

				/* The cache is still good. */
				rcu_read_unlock();
				return;
			}
		}

		changed |= permits->invalidated;
		size = permits->nr_permits;

		/* If this set of permits is now wrong, clear the permits
		 * pointer so that no one tries to use the stale information.
		 */
		if (changed) {
			spin_lock(&vnode->lock);
			if (permits != rcu_access_pointer(vnode->permit_cache))
				goto someone_else_changed_it_unlock;
			RCU_INIT_POINTER(vnode->permit_cache, NULL);
			spin_unlock(&vnode->lock);

			afs_put_permits(permits);
			permits = NULL;
			size = 0;
		}
	}

	if (afs_cb_is_broken(cb_break, vnode, vnode->cb_interest))
		goto someone_else_changed_it;

	/* We need a ref on any permits list we want to copy as we'll have to
	 * drop the lock to do memory allocation.
	 */
	if (permits && !refcount_inc_not_zero(&permits->usage))
		goto someone_else_changed_it;

	rcu_read_unlock();

	/* Speculatively create a new list with the revised permission set.  We
	 * discard this if we find an extant match already in the hash, but
	 * it's easier to compare with memcmp this way.
	 *
	 * We fill in the key pointers at this time, but we don't get the refs
	 * yet.
	 */
	size++;
	new = kzalloc(sizeof(struct afs_permits) +
		      sizeof(struct afs_permit) * size, GFP_NOFS);
	if (!new)
		goto out_put;

	refcount_set(&new->usage, 1);
	new->nr_permits = size;
	i = j = 0;
	if (permits) {
		for (i = 0; i < permits->nr_permits; i++) {
			if (j == i && permits->permits[i].key > key) {
				new->permits[j].key = key;
				new->permits[j].access = caller_access;
				j++;
			}
			new->permits[j].key = permits->permits[i].key;
			new->permits[j].access = permits->permits[i].access;
			j++;
		}
	}

	if (j == i) {
		new->permits[j].key = key;
		new->permits[j].access = caller_access;
	}

	afs_hash_permits(new);

	/* Now see if the permit list we want is actually already available */
	spin_lock(&afs_permits_lock);

	hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
		if (xpermits->h != new->h ||
		    xpermits->invalidated ||
		    xpermits->nr_permits != new->nr_permits ||
		    memcmp(xpermits->permits, new->permits,
			   new->nr_permits * sizeof(struct afs_permit)) != 0)
			continue;

		if (refcount_inc_not_zero(&xpermits->usage)) {
			replacement = xpermits;
			goto found;
		}

		break;
	}

	for (i = 0; i < new->nr_permits; i++)
		key_get(new->permits[i].key);
	hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
	replacement = new;
	new = NULL;

found:
	spin_unlock(&afs_permits_lock);

	kfree(new);

	spin_lock(&vnode->lock);
	zap = rcu_access_pointer(vnode->permit_cache);
	if (!afs_cb_is_broken(cb_break, vnode, vnode->cb_interest) &&
	    zap == permits)
		rcu_assign_pointer(vnode->permit_cache, replacement);
	else
		zap = replacement;
	spin_unlock(&vnode->lock);
	afs_put_permits(zap);
out_put:
	afs_put_permits(permits);
	return;

someone_else_changed_it_unlock:
	spin_unlock(&vnode->lock);
someone_else_changed_it:
	/* Someone else changed the cache under us - don't recheck at this
	 * time.
	 */
	rcu_read_unlock();
	return;
}

/*
 * check with the fileserver to see if the directory or parent directory is
 * permitted to be accessed with this authorisation, and if so, what access it
 * is granted
 */
int afs_check_permit(struct afs_vnode *vnode, struct key *key,
		     afs_access_t *_access)
{
	struct afs_permits *permits;
	bool valid = false;
	int i, ret;

	_enter("{%llx:%llu},%x",
	       vnode->fid.vid, vnode->fid.vnode, key_serial(key));

	/* check the permits to see if we've got one yet */
	if (key == vnode->volume->cell->anonymous_key) {
		_debug("anon");
		*_access = vnode->status.anon_access;
		valid = true;
	} else {
		rcu_read_lock();
		permits = rcu_dereference(vnode->permit_cache);
		if (permits) {
			for (i = 0; i < permits->nr_permits; i++) {
				if (permits->permits[i].key < key)
					continue;
				if (permits->permits[i].key > key)
					break;

				*_access = permits->permits[i].access;
				valid = !permits->invalidated;
				break;
			}
		}
		rcu_read_unlock();
	}

	if (!valid) {
		/* Check the status on the file we're actually interested in
		 * (the post-processing will cache the result).
		 */
		_debug("no valid permit");

		ret = afs_fetch_status(vnode, key, false);
		if (ret < 0) {
			*_access = 0;
			_leave(" = %d", ret);
			return ret;
		}
		*_access = vnode->status.caller_access;
	}

	_leave(" = 0 [access %x]", *_access);
	return 0;
}

/*
 * check the permissions on an AFS file
 * - AFS ACLs are attached to directories only, and a file is controlled by its
 *   parent directory's ACL
 */
int afs_permission(struct inode *inode, int mask)
{
	struct afs_vnode *vnode = AFS_FS_I(inode);
	afs_access_t uninitialized_var(access);
	struct key *key;
	int ret;

	if (mask & MAY_NOT_BLOCK)
		return -ECHILD;

	_enter("{{%llx:%llu},%lx},%x,",
	       vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);

	key = afs_request_key(vnode->volume->cell);
	if (IS_ERR(key)) {
		_leave(" = %ld [key]", PTR_ERR(key));
		return PTR_ERR(key);
	}

	ret = afs_validate(vnode, key);
	if (ret < 0)
		goto error;

	/* check the permits to see if we've got one yet */
	ret = afs_check_permit(vnode, key, &access);
	if (ret < 0)
		goto error;

	/* interpret the access mask */
	_debug("REQ %x ACC %x on %s",
	       mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");

	if (S_ISDIR(inode->i_mode)) {
		if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) {
			if (!(access & AFS_ACE_LOOKUP))
				goto permission_denied;
		}
		if (mask & MAY_WRITE) {
			if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */
					AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
				goto permission_denied;
		}
	} else {
		if (!(access & AFS_ACE_LOOKUP))
			goto permission_denied;
		if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
			goto permission_denied;
		if (mask & (MAY_EXEC | MAY_READ)) {
			if (!(access & AFS_ACE_READ))
				goto permission_denied;
			if (!(inode->i_mode & S_IRUSR))
				goto permission_denied;
		} else if (mask & MAY_WRITE) {
			if (!(access & AFS_ACE_WRITE))
				goto permission_denied;
			if (!(inode->i_mode & S_IWUSR))
				goto permission_denied;
		}
	}

	key_put(key);
	_leave(" = %d", ret);
	return ret;

permission_denied:
	ret = -EACCES;
error:
	key_put(key);
	_leave(" = %d", ret);
	return ret;
}

void __exit afs_clean_up_permit_cache(void)
{
	int i;

	for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
		WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));

}
Commit	Line	Data
00d3b7a4 DH	1	/* AFS security handling
00d3b7a4 DH	2	*
be080a6f	3	* Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
00d3b7a4 DH	4	* Written by David Howells (dhowells@redhat.com)
	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/init.h>
	13	#include <linux/slab.h>
	14	#include <linux/fs.h>
	15	#include <linux/ctype.h>
e8edc6e0	16	#include <linux/sched.h>
be080a6f	17	#include <linux/hashtable.h>
00d3b7a4 DH	18	#include <keys/rxrpc-type.h>
	19	#include "internal.h"
	20
be080a6f DH	21	static DEFINE_HASHTABLE(afs_permits_cache, 10);
	22	static DEFINE_SPINLOCK(afs_permits_lock);
	23
00d3b7a4 DH	24	/*
	25	* get a key
	26	*/
	27	struct key afs_request_key(struct afs_cell cell)
	28	{
	29	struct key *key;
	30
	31	_enter("{%x}", key_serial(cell->anonymous_key));
	32
	33	_debug("key %s", cell->anonymous_key->description);
	34	key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
	35	NULL);
	36	if (IS_ERR(key)) {
	37	if (PTR_ERR(key) != -ENOKEY) {
	38	_leave(" = %ld", PTR_ERR(key));
	39	return key;
	40	}
	41
	42	/* act as anonymous user */
	43	_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
	44	return key_get(cell->anonymous_key);
	45	} else {
	46	/* act as authorised user */
	47	_leave(" = {%x} [auth]", key_serial(key));
	48	return key;
	49	}
	50	}
	51
	52	/*
be080a6f	53	* Dispose of a list of permits.
00d3b7a4	54	*/
be080a6f	55	static void afs_permits_rcu(struct rcu_head *rcu)
00d3b7a4 DH	56	{
	57	struct afs_permits *permits =
	58	container_of(rcu, struct afs_permits, rcu);
be080a6f	59	int i;
00d3b7a4	60
be080a6f DH	61	for (i = 0; i < permits->nr_permits; i++)
be080a6f DH	62	key_put(permits->permits[i].key);
00d3b7a4 DH	63	kfree(permits);
	64	}
	65
	66	/*
be080a6f	67	* Discard a permission cache.
00d3b7a4	68	*/
be080a6f	69	void afs_put_permits(struct afs_permits *permits)
00d3b7a4	70	{
be080a6f DH	71	if (permits && refcount_dec_and_test(&permits->usage)) {
	72	spin_lock(&afs_permits_lock);
	73	hash_del_rcu(&permits->hash_node);
	74	spin_unlock(&afs_permits_lock);
	75	call_rcu(&permits->rcu, afs_permits_rcu);
	76	}
00d3b7a4 DH	77	}
	78
	79	/*
be080a6f	80	* Clear a permit cache on callback break.
00d3b7a4	81	*/
be080a6f	82	void afs_clear_permits(struct afs_vnode *vnode)
00d3b7a4	83	{
be080a6f	84	struct afs_permits *permits;
00d3b7a4	85
be080a6f DH	86	spin_lock(&vnode->lock);
	87	permits = rcu_dereference_protected(vnode->permit_cache,
	88	lockdep_is_held(&vnode->lock));
	89	RCU_INIT_POINTER(vnode->permit_cache, NULL);
	90	vnode->cb_break++;
	91	spin_unlock(&vnode->lock);
00d3b7a4	92
be080a6f DH	93	if (permits)
be080a6f DH	94	afs_put_permits(permits);
00d3b7a4 DH	95	}
	96
	97	/*
be080a6f DH	98	* Hash a list of permits. Use simple addition to make it easy to add an extra
be080a6f DH	99	* one at an as-yet indeterminate position in the list.
00d3b7a4	100	*/
be080a6f	101	static void afs_hash_permits(struct afs_permits *permits)
00d3b7a4	102	{
be080a6f DH	103	unsigned long h = permits->nr_permits;
be080a6f DH	104	int i;
00d3b7a4	105
be080a6f DH	106	for (i = 0; i < permits->nr_permits; i++) {
	107	h += (unsigned long)permits->permits[i].key / sizeof(void *);
	108	h += permits->permits[i].access;
	109	}
00d3b7a4	110
be080a6f	111	permits->h = h;
00d3b7a4 DH	112	}
	113
	114	/*
be080a6f DH	115	* Cache the CallerAccess result obtained from doing a fileserver operation
	116	* that returned a vnode status for a particular key. If a callback break
	117	* occurs whilst the operation was in progress then we have to ditch the cache
	118	* as the ACL may have changed.
00d3b7a4	119	*/
be080a6f DH	120	void afs_cache_permit(struct afs_vnode vnode, struct key key,
be080a6f DH	121	unsigned int cb_break)
00d3b7a4	122	{
1bcab125	123	struct afs_permits permits, xpermits, replacement, zap, *new = NULL;
be080a6f DH	124	afs_access_t caller_access = READ_ONCE(vnode->status.caller_access);
	125	size_t size = 0;
	126	bool changed = false;
	127	int i, j;
	128
3b6492df	129	_enter("{%llx:%llu},%x,%x",
be080a6f DH	130	vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
	131
	132	rcu_read_lock();
	133
	134	/* Check for the common case first: We got back the same access as last
	135	* time we tried and already have it recorded.
	136	*/
	137	permits = rcu_dereference(vnode->permit_cache);
	138	if (permits) {
	139	if (!permits->invalidated) {
	140	for (i = 0; i < permits->nr_permits; i++) {
	141	if (permits->permits[i].key < key)
	142	continue;
	143	if (permits->permits[i].key > key)
	144	break;
	145	if (permits->permits[i].access != caller_access) {
	146	changed = true;
	147	break;
	148	}
00d3b7a4	149
18ac6185 DH	150	if (afs_cb_is_broken(cb_break, vnode,
18ac6185 DH	151	vnode->cb_interest)) {
be080a6f DH	152	changed = true;
	153	break;
	154	}
00d3b7a4	155
be080a6f DH	156	/* The cache is still good. */
	157	rcu_read_unlock();
	158	return;
	159	}
	160	}
00d3b7a4	161
be080a6f DH	162	changed \|= permits->invalidated;
be080a6f DH	163	size = permits->nr_permits;
00d3b7a4	164
be080a6f DH	165	/* If this set of permits is now wrong, clear the permits
	166	* pointer so that no one tries to use the stale information.
	167	*/
	168	if (changed) {
	169	spin_lock(&vnode->lock);
	170	if (permits != rcu_access_pointer(vnode->permit_cache))
	171	goto someone_else_changed_it_unlock;
	172	RCU_INIT_POINTER(vnode->permit_cache, NULL);
	173	spin_unlock(&vnode->lock);
	174
	175	afs_put_permits(permits);
	176	permits = NULL;
	177	size = 0;
	178	}
00d3b7a4 DH	179	}
00d3b7a4 DH	180
18ac6185	181	if (afs_cb_is_broken(cb_break, vnode, vnode->cb_interest))
be080a6f	182	goto someone_else_changed_it;
00d3b7a4	183
be080a6f DH	184	/* We need a ref on any permits list we want to copy as we'll have to
	185	* drop the lock to do memory allocation.
	186	*/
fe342cf7	187	if (permits && !refcount_inc_not_zero(&permits->usage))
be080a6f	188	goto someone_else_changed_it;
be080a6f DH	189
	190	rcu_read_unlock();
	191
	192	/* Speculatively create a new list with the revised permission set. We
	193	* discard this if we find an extant match already in the hash, but
	194	* it's easier to compare with memcmp this way.
	195	*
	196	* We fill in the key pointers at this time, but we don't get the refs
	197	* yet.
	198	*/
	199	size++;
	200	new = kzalloc(sizeof(struct afs_permits) +
	201	sizeof(struct afs_permit) * size, GFP_NOFS);
	202	if (!new)
1bcab125	203	goto out_put;
be080a6f DH	204
	205	refcount_set(&new->usage, 1);
	206	new->nr_permits = size;
	207	i = j = 0;
	208	if (permits) {
	209	for (i = 0; i < permits->nr_permits; i++) {
	210	if (j == i && permits->permits[i].key > key) {
	211	new->permits[j].key = key;
	212	new->permits[j].access = caller_access;
	213	j++;
00d3b7a4	214	}
be080a6f DH	215	new->permits[j].key = permits->permits[i].key;
	216	new->permits[j].access = permits->permits[i].access;
	217	j++;
00d3b7a4 DH	218	}
	219	}
	220
be080a6f DH	221	if (j == i) {
	222	new->permits[j].key = key;
	223	new->permits[j].access = caller_access;
	224	}
	225
	226	afs_hash_permits(new);
	227
be080a6f DH	228	/* Now see if the permit list we want is actually already available */
	229	spin_lock(&afs_permits_lock);
	230
	231	hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
	232	if (xpermits->h != new->h \|\|
	233	xpermits->invalidated \|\|
	234	xpermits->nr_permits != new->nr_permits \|\|
	235	memcmp(xpermits->permits, new->permits,
	236	new->nr_permits * sizeof(struct afs_permit)) != 0)
	237	continue;
	238
	239	if (refcount_inc_not_zero(&xpermits->usage)) {
	240	replacement = xpermits;
	241	goto found;
	242	}
	243
	244	break;
	245	}
	246
	247	for (i = 0; i < new->nr_permits; i++)
	248	key_get(new->permits[i].key);
	249	hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
	250	replacement = new;
	251	new = NULL;
	252
	253	found:
	254	spin_unlock(&afs_permits_lock);
	255
	256	kfree(new);
	257
	258	spin_lock(&vnode->lock);
1bcab125	259	zap = rcu_access_pointer(vnode->permit_cache);
18ac6185	260	if (!afs_cb_is_broken(cb_break, vnode, vnode->cb_interest) &&
1bcab125 DH	261	zap == permits)
	262	rcu_assign_pointer(vnode->permit_cache, replacement);
	263	else
	264	zap = replacement;
be080a6f	265	spin_unlock(&vnode->lock);
1bcab125 DH	266	afs_put_permits(zap);
1bcab125 DH	267	out_put:
be080a6f DH	268	afs_put_permits(permits);
	269	return;
	270
	271	someone_else_changed_it_unlock:
	272	spin_unlock(&vnode->lock);
	273	someone_else_changed_it:
	274	/* Someone else changed the cache under us - don't recheck at this
	275	* time.
	276	*/
fe342cf7	277	rcu_read_unlock();
be080a6f	278	return;
00d3b7a4 DH	279	}
	280
	281	/*
	282	* check with the fileserver to see if the directory or parent directory is
	283	* permitted to be accessed with this authorisation, and if so, what access it
	284	* is granted
	285	*/
0fafdc9f DH	286	int afs_check_permit(struct afs_vnode vnode, struct key key,
0fafdc9f DH	287	afs_access_t *_access)
00d3b7a4 DH	288	{
00d3b7a4 DH	289	struct afs_permits *permits;
be080a6f DH	290	bool valid = false;
be080a6f DH	291	int i, ret;
00d3b7a4	292
3b6492df	293	_enter("{%llx:%llu},%x",
416351f2	294	vnode->fid.vid, vnode->fid.vnode, key_serial(key));
00d3b7a4	295
00d3b7a4	296	/* check the permits to see if we've got one yet */
be080a6f	297	if (key == vnode->volume->cell->anonymous_key) {
00d3b7a4	298	_debug("anon");
be080a6f	299	*_access = vnode->status.anon_access;
00d3b7a4 DH	300	valid = true;
00d3b7a4 DH	301	} else {
00d3b7a4	302	rcu_read_lock();
be080a6f	303	permits = rcu_dereference(vnode->permit_cache);
00d3b7a4	304	if (permits) {
be080a6f DH	305	for (i = 0; i < permits->nr_permits; i++) {
	306	if (permits->permits[i].key < key)
	307	continue;
	308	if (permits->permits[i].key > key)
00d3b7a4	309	break;
be080a6f DH	310
	311	*_access = permits->permits[i].access;
	312	valid = !permits->invalidated;
	313	break;
00d3b7a4 DH	314	}
	315	}
	316	rcu_read_unlock();
	317	}
	318
	319	if (!valid) {
be080a6f DH	320	/* Check the status on the file we're actually interested in
	321	* (the post-processing will cache the result).
	322	*/
00d3b7a4 DH	323	_debug("no valid permit");
00d3b7a4 DH	324
0c3a5ac2	325	ret = afs_fetch_status(vnode, key, false);
00d3b7a4	326	if (ret < 0) {
00d3b7a4 DH	327	*_access = 0;
	328	_leave(" = %d", ret);
	329	return ret;
	330	}
416351f2	331	*_access = vnode->status.caller_access;
00d3b7a4 DH	332	}
00d3b7a4 DH	333
00d3b7a4 DH	334	_leave(" = 0 [access %x]", *_access);
	335	return 0;
	336	}
	337
	338	/*
	339	* check the permissions on an AFS file
	340	* - AFS ACLs are attached to directories only, and a file is controlled by its
	341	* parent directory's ACL
	342	*/
10556cb2	343	int afs_permission(struct inode *inode, int mask)
00d3b7a4 DH	344	{
00d3b7a4 DH	345	struct afs_vnode *vnode = AFS_FS_I(inode);
69759454	346	afs_access_t uninitialized_var(access);
00d3b7a4 DH	347	struct key *key;
	348	int ret;
	349
10556cb2	350	if (mask & MAY_NOT_BLOCK)
b74c79e9 NP	351	return -ECHILD;
b74c79e9 NP	352
3b6492df	353	_enter("{{%llx:%llu},%lx},%x,",
260a9803	354	vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
00d3b7a4 DH	355
	356	key = afs_request_key(vnode->volume->cell);
	357	if (IS_ERR(key)) {
	358	_leave(" = %ld [key]", PTR_ERR(key));
	359	return PTR_ERR(key);
	360	}
	361
c435ee34 DH	362	ret = afs_validate(vnode, key);
	363	if (ret < 0)
	364	goto error;
260a9803	365
00d3b7a4 DH	366	/* check the permits to see if we've got one yet */
00d3b7a4 DH	367	ret = afs_check_permit(vnode, key, &access);
260a9803 DH	368	if (ret < 0)
260a9803 DH	369	goto error;
00d3b7a4 DH	370
	371	/* interpret the access mask */
	372	_debug("REQ %x ACC %x on %s",
	373	mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
	374
	375	if (S_ISDIR(inode->i_mode)) {
378831e4	376	if (mask & (MAY_EXEC \| MAY_READ \| MAY_CHDIR)) {
00d3b7a4 DH	377	if (!(access & AFS_ACE_LOOKUP))
00d3b7a4 DH	378	goto permission_denied;
378831e4 DH	379	}
378831e4 DH	380	if (mask & MAY_WRITE) {
00d3b7a4	381	if (!(access & (AFS_ACE_DELETE \| /* rmdir, unlink, rename from */
fd249821	382	AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
00d3b7a4	383	goto permission_denied;
00d3b7a4 DH	384	}
	385	} else {
	386	if (!(access & AFS_ACE_LOOKUP))
	387	goto permission_denied;
627f4694 MD	388	if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
627f4694 MD	389	goto permission_denied;
00d3b7a4 DH	390	if (mask & (MAY_EXEC \| MAY_READ)) {
	391	if (!(access & AFS_ACE_READ))
	392	goto permission_denied;
627f4694 MD	393	if (!(inode->i_mode & S_IRUSR))
627f4694 MD	394	goto permission_denied;
00d3b7a4 DH	395	} else if (mask & MAY_WRITE) {
	396	if (!(access & AFS_ACE_WRITE))
	397	goto permission_denied;
627f4694 MD	398	if (!(inode->i_mode & S_IWUSR))
627f4694 MD	399	goto permission_denied;
00d3b7a4 DH	400	}
	401	}
	402
	403	key_put(key);
260a9803 DH	404	_leave(" = %d", ret);
260a9803 DH	405	return ret;
00d3b7a4 DH	406
00d3b7a4 DH	407	permission_denied:
260a9803 DH	408	ret = -EACCES;
260a9803 DH	409	error:
00d3b7a4	410	key_put(key);
260a9803 DH	411	_leave(" = %d", ret);
260a9803 DH	412	return ret;
00d3b7a4	413	}
be080a6f DH	414
	415	void __exit afs_clean_up_permit_cache(void)
	416	{
	417	int i;
	418
	419	for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
	420	WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
	421
	422	}