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

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS security handling
 *
 * Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#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);
	spin_unlock(&vnode->lock);

	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_status_cb *scb)
{
	struct afs_permits *permits, *xpermits, *replacement, *zap, *new = NULL;
	afs_access_t caller_access = scb->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,
						     rcu_dereference(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, rcu_dereference(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);

	rcu_read_lock();
	spin_lock(&vnode->lock);
	zap = rcu_access_pointer(vnode->permit_cache);
	if (!afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)) &&
	    zap == permits)
		rcu_assign_pointer(vnode->permit_cache, replacement);
	else
		zap = replacement;
	spin_unlock(&vnode->lock);
	rcu_read_unlock();
	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, _access);
		if (ret < 0) {
			*_access = 0;
			_leave(" = %d", ret);
			return ret;
		}
	}

	_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
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
00d3b7a4 DH	2	/* AFS security handling
00d3b7a4 DH	3	*
be080a6f	4	* Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
00d3b7a4	5	* Written by David Howells (dhowells@redhat.com)
00d3b7a4 DH	6	*/
	7
	8	#include <linux/init.h>
	9	#include <linux/slab.h>
	10	#include <linux/fs.h>
	11	#include <linux/ctype.h>
e8edc6e0	12	#include <linux/sched.h>
be080a6f	13	#include <linux/hashtable.h>
00d3b7a4 DH	14	#include <keys/rxrpc-type.h>
	15	#include "internal.h"
	16
be080a6f DH	17	static DEFINE_HASHTABLE(afs_permits_cache, 10);
	18	static DEFINE_SPINLOCK(afs_permits_lock);
	19
00d3b7a4 DH	20	/*
	21	* get a key
	22	*/
	23	struct key afs_request_key(struct afs_cell cell)
	24	{
	25	struct key *key;
	26
	27	_enter("{%x}", key_serial(cell->anonymous_key));
	28
	29	_debug("key %s", cell->anonymous_key->description);
	30	key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
	31	NULL);
	32	if (IS_ERR(key)) {
	33	if (PTR_ERR(key) != -ENOKEY) {
	34	_leave(" = %ld", PTR_ERR(key));
	35	return key;
	36	}
	37
	38	/* act as anonymous user */
	39	_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
	40	return key_get(cell->anonymous_key);
	41	} else {
	42	/* act as authorised user */
	43	_leave(" = {%x} [auth]", key_serial(key));
	44	return key;
	45	}
	46	}
	47
	48	/*
be080a6f	49	* Dispose of a list of permits.
00d3b7a4	50	*/
be080a6f	51	static void afs_permits_rcu(struct rcu_head *rcu)
00d3b7a4 DH	52	{
	53	struct afs_permits *permits =
	54	container_of(rcu, struct afs_permits, rcu);
be080a6f	55	int i;
00d3b7a4	56
be080a6f DH	57	for (i = 0; i < permits->nr_permits; i++)
be080a6f DH	58	key_put(permits->permits[i].key);
00d3b7a4 DH	59	kfree(permits);
	60	}
	61
	62	/*
be080a6f	63	* Discard a permission cache.
00d3b7a4	64	*/
be080a6f	65	void afs_put_permits(struct afs_permits *permits)
00d3b7a4	66	{
be080a6f DH	67	if (permits && refcount_dec_and_test(&permits->usage)) {
	68	spin_lock(&afs_permits_lock);
	69	hash_del_rcu(&permits->hash_node);
	70	spin_unlock(&afs_permits_lock);
	71	call_rcu(&permits->rcu, afs_permits_rcu);
	72	}
00d3b7a4 DH	73	}
	74
	75	/*
be080a6f	76	* Clear a permit cache on callback break.
00d3b7a4	77	*/
be080a6f	78	void afs_clear_permits(struct afs_vnode *vnode)
00d3b7a4	79	{
be080a6f	80	struct afs_permits *permits;
00d3b7a4	81
be080a6f DH	82	spin_lock(&vnode->lock);
	83	permits = rcu_dereference_protected(vnode->permit_cache,
	84	lockdep_is_held(&vnode->lock));
	85	RCU_INIT_POINTER(vnode->permit_cache, NULL);
be080a6f	86	spin_unlock(&vnode->lock);
00d3b7a4	87
fd711586	88	afs_put_permits(permits);
00d3b7a4 DH	89	}
	90
	91	/*
be080a6f DH	92	* Hash a list of permits. Use simple addition to make it easy to add an extra
be080a6f DH	93	* one at an as-yet indeterminate position in the list.
00d3b7a4	94	*/
be080a6f	95	static void afs_hash_permits(struct afs_permits *permits)
00d3b7a4	96	{
be080a6f DH	97	unsigned long h = permits->nr_permits;
be080a6f DH	98	int i;
00d3b7a4	99
be080a6f DH	100	for (i = 0; i < permits->nr_permits; i++) {
	101	h += (unsigned long)permits->permits[i].key / sizeof(void *);
	102	h += permits->permits[i].access;
	103	}
00d3b7a4	104
be080a6f	105	permits->h = h;
00d3b7a4 DH	106	}
	107
	108	/*
be080a6f DH	109	* Cache the CallerAccess result obtained from doing a fileserver operation
	110	* that returned a vnode status for a particular key. If a callback break
	111	* occurs whilst the operation was in progress then we have to ditch the cache
	112	* as the ACL may have changed.
00d3b7a4	113	*/
be080a6f	114	void afs_cache_permit(struct afs_vnode vnode, struct key key,
a58823ac	115	unsigned int cb_break, struct afs_status_cb *scb)
00d3b7a4	116	{
1bcab125	117	struct afs_permits permits, xpermits, replacement, zap, *new = NULL;
a58823ac	118	afs_access_t caller_access = scb->status.caller_access;
be080a6f DH	119	size_t size = 0;
	120	bool changed = false;
	121	int i, j;
	122
3b6492df	123	_enter("{%llx:%llu},%x,%x",
be080a6f DH	124	vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
	125
	126	rcu_read_lock();
	127
	128	/* Check for the common case first: We got back the same access as last
	129	* time we tried and already have it recorded.
	130	*/
	131	permits = rcu_dereference(vnode->permit_cache);
	132	if (permits) {
	133	if (!permits->invalidated) {
	134	for (i = 0; i < permits->nr_permits; i++) {
	135	if (permits->permits[i].key < key)
	136	continue;
	137	if (permits->permits[i].key > key)
	138	break;
	139	if (permits->permits[i].access != caller_access) {
	140	changed = true;
	141	break;
	142	}
00d3b7a4	143
18ac6185	144	if (afs_cb_is_broken(cb_break, vnode,
f642404a	145	rcu_dereference(vnode->cb_interest))) {
be080a6f DH	146	changed = true;
	147	break;
	148	}
00d3b7a4	149
be080a6f DH	150	/* The cache is still good. */
	151	rcu_read_unlock();
	152	return;
	153	}
	154	}
00d3b7a4	155
be080a6f DH	156	changed \|= permits->invalidated;
be080a6f DH	157	size = permits->nr_permits;
00d3b7a4	158
be080a6f DH	159	/* If this set of permits is now wrong, clear the permits
	160	* pointer so that no one tries to use the stale information.
	161	*/
	162	if (changed) {
	163	spin_lock(&vnode->lock);
	164	if (permits != rcu_access_pointer(vnode->permit_cache))
	165	goto someone_else_changed_it_unlock;
	166	RCU_INIT_POINTER(vnode->permit_cache, NULL);
	167	spin_unlock(&vnode->lock);
	168
	169	afs_put_permits(permits);
	170	permits = NULL;
	171	size = 0;
	172	}
00d3b7a4 DH	173	}
00d3b7a4 DH	174
f642404a	175	if (afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)))
be080a6f	176	goto someone_else_changed_it;
00d3b7a4	177
be080a6f DH	178	/* We need a ref on any permits list we want to copy as we'll have to
	179	* drop the lock to do memory allocation.
	180	*/
fe342cf7	181	if (permits && !refcount_inc_not_zero(&permits->usage))
be080a6f	182	goto someone_else_changed_it;
be080a6f DH	183
	184	rcu_read_unlock();
	185
	186	/* Speculatively create a new list with the revised permission set. We
	187	* discard this if we find an extant match already in the hash, but
	188	* it's easier to compare with memcmp this way.
	189	*
	190	* We fill in the key pointers at this time, but we don't get the refs
	191	* yet.
	192	*/
	193	size++;
	194	new = kzalloc(sizeof(struct afs_permits) +
	195	sizeof(struct afs_permit) * size, GFP_NOFS);
	196	if (!new)
1bcab125	197	goto out_put;
be080a6f DH	198
	199	refcount_set(&new->usage, 1);
	200	new->nr_permits = size;
	201	i = j = 0;
	202	if (permits) {
	203	for (i = 0; i < permits->nr_permits; i++) {
	204	if (j == i && permits->permits[i].key > key) {
	205	new->permits[j].key = key;
	206	new->permits[j].access = caller_access;
	207	j++;
00d3b7a4	208	}
be080a6f DH	209	new->permits[j].key = permits->permits[i].key;
	210	new->permits[j].access = permits->permits[i].access;
	211	j++;
00d3b7a4 DH	212	}
	213	}
	214
be080a6f DH	215	if (j == i) {
	216	new->permits[j].key = key;
	217	new->permits[j].access = caller_access;
	218	}
	219
	220	afs_hash_permits(new);
	221
be080a6f DH	222	/* Now see if the permit list we want is actually already available */
	223	spin_lock(&afs_permits_lock);
	224
	225	hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
	226	if (xpermits->h != new->h \|\|
	227	xpermits->invalidated \|\|
	228	xpermits->nr_permits != new->nr_permits \|\|
	229	memcmp(xpermits->permits, new->permits,
	230	new->nr_permits * sizeof(struct afs_permit)) != 0)
	231	continue;
	232
	233	if (refcount_inc_not_zero(&xpermits->usage)) {
	234	replacement = xpermits;
	235	goto found;
	236	}
	237
	238	break;
	239	}
	240
	241	for (i = 0; i < new->nr_permits; i++)
	242	key_get(new->permits[i].key);
	243	hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
	244	replacement = new;
	245	new = NULL;
	246
	247	found:
	248	spin_unlock(&afs_permits_lock);
	249
	250	kfree(new);
	251
f642404a	252	rcu_read_lock();
be080a6f	253	spin_lock(&vnode->lock);
1bcab125	254	zap = rcu_access_pointer(vnode->permit_cache);
f642404a	255	if (!afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)) &&
1bcab125 DH	256	zap == permits)
	257	rcu_assign_pointer(vnode->permit_cache, replacement);
	258	else
	259	zap = replacement;
be080a6f	260	spin_unlock(&vnode->lock);
f642404a	261	rcu_read_unlock();
1bcab125 DH	262	afs_put_permits(zap);
1bcab125 DH	263	out_put:
be080a6f DH	264	afs_put_permits(permits);
	265	return;
	266
	267	someone_else_changed_it_unlock:
	268	spin_unlock(&vnode->lock);
	269	someone_else_changed_it:
	270	/* Someone else changed the cache under us - don't recheck at this
	271	* time.
	272	*/
fe342cf7	273	rcu_read_unlock();
be080a6f	274	return;
00d3b7a4 DH	275	}
	276
	277	/*
	278	* check with the fileserver to see if the directory or parent directory is
	279	* permitted to be accessed with this authorisation, and if so, what access it
	280	* is granted
	281	*/
0fafdc9f DH	282	int afs_check_permit(struct afs_vnode vnode, struct key key,
0fafdc9f DH	283	afs_access_t *_access)
00d3b7a4 DH	284	{
00d3b7a4 DH	285	struct afs_permits *permits;
be080a6f DH	286	bool valid = false;
be080a6f DH	287	int i, ret;
00d3b7a4	288
3b6492df	289	_enter("{%llx:%llu},%x",
416351f2	290	vnode->fid.vid, vnode->fid.vnode, key_serial(key));
00d3b7a4	291
00d3b7a4	292	/* check the permits to see if we've got one yet */
be080a6f	293	if (key == vnode->volume->cell->anonymous_key) {
00d3b7a4	294	_debug("anon");
be080a6f	295	*_access = vnode->status.anon_access;
00d3b7a4 DH	296	valid = true;
00d3b7a4 DH	297	} else {
00d3b7a4	298	rcu_read_lock();
be080a6f	299	permits = rcu_dereference(vnode->permit_cache);
00d3b7a4	300	if (permits) {
be080a6f DH	301	for (i = 0; i < permits->nr_permits; i++) {
	302	if (permits->permits[i].key < key)
	303	continue;
	304	if (permits->permits[i].key > key)
00d3b7a4	305	break;
be080a6f DH	306
	307	*_access = permits->permits[i].access;
	308	valid = !permits->invalidated;
	309	break;
00d3b7a4 DH	310	}
	311	}
	312	rcu_read_unlock();
	313	}
	314
	315	if (!valid) {
be080a6f DH	316	/* Check the status on the file we're actually interested in
	317	* (the post-processing will cache the result).
	318	*/
00d3b7a4 DH	319	_debug("no valid permit");
00d3b7a4 DH	320
a58823ac	321	ret = afs_fetch_status(vnode, key, false, _access);
00d3b7a4	322	if (ret < 0) {
00d3b7a4 DH	323	*_access = 0;
	324	_leave(" = %d", ret);
	325	return ret;
	326	}
	327	}
	328
00d3b7a4 DH	329	_leave(" = 0 [access %x]", *_access);
	330	return 0;
	331	}
	332
	333	/*
	334	* check the permissions on an AFS file
	335	* - AFS ACLs are attached to directories only, and a file is controlled by its
	336	* parent directory's ACL
	337	*/
10556cb2	338	int afs_permission(struct inode *inode, int mask)
00d3b7a4 DH	339	{
00d3b7a4 DH	340	struct afs_vnode *vnode = AFS_FS_I(inode);
69759454	341	afs_access_t uninitialized_var(access);
00d3b7a4 DH	342	struct key *key;
	343	int ret;
	344
10556cb2	345	if (mask & MAY_NOT_BLOCK)
b74c79e9 NP	346	return -ECHILD;
b74c79e9 NP	347
3b6492df	348	_enter("{{%llx:%llu},%lx},%x,",
260a9803	349	vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
00d3b7a4 DH	350
	351	key = afs_request_key(vnode->volume->cell);
	352	if (IS_ERR(key)) {
	353	_leave(" = %ld [key]", PTR_ERR(key));
	354	return PTR_ERR(key);
	355	}
	356
c435ee34 DH	357	ret = afs_validate(vnode, key);
	358	if (ret < 0)
	359	goto error;
260a9803	360
00d3b7a4 DH	361	/* check the permits to see if we've got one yet */
00d3b7a4 DH	362	ret = afs_check_permit(vnode, key, &access);
260a9803 DH	363	if (ret < 0)
260a9803 DH	364	goto error;
00d3b7a4 DH	365
	366	/* interpret the access mask */
	367	_debug("REQ %x ACC %x on %s",
	368	mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
	369
	370	if (S_ISDIR(inode->i_mode)) {
378831e4	371	if (mask & (MAY_EXEC \| MAY_READ \| MAY_CHDIR)) {
00d3b7a4 DH	372	if (!(access & AFS_ACE_LOOKUP))
00d3b7a4 DH	373	goto permission_denied;
378831e4 DH	374	}
378831e4 DH	375	if (mask & MAY_WRITE) {
00d3b7a4	376	if (!(access & (AFS_ACE_DELETE \| /* rmdir, unlink, rename from */
fd249821	377	AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
00d3b7a4	378	goto permission_denied;
00d3b7a4 DH	379	}
	380	} else {
	381	if (!(access & AFS_ACE_LOOKUP))
	382	goto permission_denied;
627f4694 MD	383	if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
627f4694 MD	384	goto permission_denied;
00d3b7a4 DH	385	if (mask & (MAY_EXEC \| MAY_READ)) {
	386	if (!(access & AFS_ACE_READ))
	387	goto permission_denied;
627f4694 MD	388	if (!(inode->i_mode & S_IRUSR))
627f4694 MD	389	goto permission_denied;
00d3b7a4 DH	390	} else if (mask & MAY_WRITE) {
	391	if (!(access & AFS_ACE_WRITE))
	392	goto permission_denied;
627f4694 MD	393	if (!(inode->i_mode & S_IWUSR))
627f4694 MD	394	goto permission_denied;
00d3b7a4 DH	395	}
	396	}
	397
	398	key_put(key);
260a9803 DH	399	_leave(" = %d", ret);
260a9803 DH	400	return ret;
00d3b7a4 DH	401
00d3b7a4 DH	402	permission_denied:
260a9803 DH	403	ret = -EACCES;
260a9803 DH	404	error:
00d3b7a4	405	key_put(key);
260a9803 DH	406	_leave(" = %d", ret);
260a9803 DH	407	return ret;
00d3b7a4	408	}
be080a6f DH	409
	410	void __exit afs_clean_up_permit_cache(void)
	411	{
	412	int i;
	413
	414	for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
	415	WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
	416
	417	}