[mirror_ubuntu-jammy-kernel.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_net(&key_type_rxrpc, cell->anonymous_key->description,
			      cell->net->net, 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;
	}
}

/*
 * Get a key when pathwalk is in rcuwalk mode.
 */
struct key *afs_request_key_rcu(struct afs_cell *cell)
{
	struct key *key;

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

	_debug("key %s", cell->anonymous_key->description);
	key = request_key_net_rcu(&key_type_rxrpc,
				  cell->anonymous_key->description,
				  cell->net->net);
	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;
}

static bool afs_check_permit_rcu(struct afs_vnode *vnode, struct key *key,
				 afs_access_t *_access)
{
	const struct afs_permits *permits;
	int i;

	_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) {
		*_access = vnode->status.anon_access;
		_leave(" = t [anon %x]", *_access);
		return true;
	}

	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;
			_leave(" = %u [perm %x]", !permits->invalidated, *_access);
			return !permits->invalidated;
		}
	}

	_leave(" = f");
	return false;
}

/*
 * 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 = 0;

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

	if (mask & MAY_NOT_BLOCK) {
		key = afs_request_key_rcu(vnode->volume->cell);
		if (IS_ERR(key))
			return -ECHILD;

		ret = -ECHILD;
		if (!afs_check_validity(vnode) ||
		    !afs_check_permit_rcu(vnode, key, &access))
			goto error;
	} else {
		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");

	ret = 0;
	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);
8b6a666a DH	30	key = request_key_net(&key_type_rxrpc, cell->anonymous_key->description,
	31	cell->net->net, 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	/*
	49	* Get a key when pathwalk is in rcuwalk mode.
	50	*/
	51	struct key afs_request_key_rcu(struct afs_cell cell)
	52	{
	53	struct key *key;
	54
	55	_enter("{%x}", key_serial(cell->anonymous_key));
	56
	57	_debug("key %s", cell->anonymous_key->description);
	58	key = request_key_net_rcu(&key_type_rxrpc,
	59	cell->anonymous_key->description,
	60	cell->net->net);
00d3b7a4 DH	61	if (IS_ERR(key)) {
	62	if (PTR_ERR(key) != -ENOKEY) {
	63	_leave(" = %ld", PTR_ERR(key));
	64	return key;
	65	}
	66
	67	/* act as anonymous user */
	68	_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
	69	return key_get(cell->anonymous_key);
	70	} else {
	71	/* act as authorised user */
	72	_leave(" = {%x} [auth]", key_serial(key));
	73	return key;
	74	}
	75	}
	76
	77	/*
be080a6f	78	* Dispose of a list of permits.
00d3b7a4	79	*/
be080a6f	80	static void afs_permits_rcu(struct rcu_head *rcu)
00d3b7a4 DH	81	{
	82	struct afs_permits *permits =
	83	container_of(rcu, struct afs_permits, rcu);
be080a6f	84	int i;
00d3b7a4	85
be080a6f DH	86	for (i = 0; i < permits->nr_permits; i++)
be080a6f DH	87	key_put(permits->permits[i].key);
00d3b7a4 DH	88	kfree(permits);
	89	}
	90
	91	/*
be080a6f	92	* Discard a permission cache.
00d3b7a4	93	*/
be080a6f	94	void afs_put_permits(struct afs_permits *permits)
00d3b7a4	95	{
be080a6f DH	96	if (permits && refcount_dec_and_test(&permits->usage)) {
	97	spin_lock(&afs_permits_lock);
	98	hash_del_rcu(&permits->hash_node);
	99	spin_unlock(&afs_permits_lock);
	100	call_rcu(&permits->rcu, afs_permits_rcu);
	101	}
00d3b7a4 DH	102	}
	103
	104	/*
be080a6f	105	* Clear a permit cache on callback break.
00d3b7a4	106	*/
be080a6f	107	void afs_clear_permits(struct afs_vnode *vnode)
00d3b7a4	108	{
be080a6f	109	struct afs_permits *permits;
00d3b7a4	110
be080a6f DH	111	spin_lock(&vnode->lock);
	112	permits = rcu_dereference_protected(vnode->permit_cache,
	113	lockdep_is_held(&vnode->lock));
	114	RCU_INIT_POINTER(vnode->permit_cache, NULL);
be080a6f	115	spin_unlock(&vnode->lock);
00d3b7a4	116
fd711586	117	afs_put_permits(permits);
00d3b7a4 DH	118	}
	119
	120	/*
be080a6f DH	121	* Hash a list of permits. Use simple addition to make it easy to add an extra
be080a6f DH	122	* one at an as-yet indeterminate position in the list.
00d3b7a4	123	*/
be080a6f	124	static void afs_hash_permits(struct afs_permits *permits)
00d3b7a4	125	{
be080a6f DH	126	unsigned long h = permits->nr_permits;
be080a6f DH	127	int i;
00d3b7a4	128
be080a6f DH	129	for (i = 0; i < permits->nr_permits; i++) {
	130	h += (unsigned long)permits->permits[i].key / sizeof(void *);
	131	h += permits->permits[i].access;
	132	}
00d3b7a4	133
be080a6f	134	permits->h = h;
00d3b7a4 DH	135	}
	136
	137	/*
be080a6f DH	138	* Cache the CallerAccess result obtained from doing a fileserver operation
	139	* that returned a vnode status for a particular key. If a callback break
	140	* occurs whilst the operation was in progress then we have to ditch the cache
	141	* as the ACL may have changed.
00d3b7a4	142	*/
be080a6f	143	void afs_cache_permit(struct afs_vnode vnode, struct key key,
a58823ac	144	unsigned int cb_break, struct afs_status_cb *scb)
00d3b7a4	145	{
1bcab125	146	struct afs_permits permits, xpermits, replacement, zap, *new = NULL;
a58823ac	147	afs_access_t caller_access = scb->status.caller_access;
be080a6f DH	148	size_t size = 0;
	149	bool changed = false;
	150	int i, j;
	151
3b6492df	152	_enter("{%llx:%llu},%x,%x",
be080a6f DH	153	vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
	154
	155	rcu_read_lock();
	156
	157	/* Check for the common case first: We got back the same access as last
	158	* time we tried and already have it recorded.
	159	*/
	160	permits = rcu_dereference(vnode->permit_cache);
	161	if (permits) {
	162	if (!permits->invalidated) {
	163	for (i = 0; i < permits->nr_permits; i++) {
	164	if (permits->permits[i].key < key)
	165	continue;
	166	if (permits->permits[i].key > key)
	167	break;
	168	if (permits->permits[i].access != caller_access) {
	169	changed = true;
	170	break;
	171	}
00d3b7a4	172
18ac6185	173	if (afs_cb_is_broken(cb_break, vnode,
f642404a	174	rcu_dereference(vnode->cb_interest))) {
be080a6f DH	175	changed = true;
	176	break;
	177	}
00d3b7a4	178
be080a6f DH	179	/* The cache is still good. */
	180	rcu_read_unlock();
	181	return;
	182	}
	183	}
00d3b7a4	184
be080a6f DH	185	changed \|= permits->invalidated;
be080a6f DH	186	size = permits->nr_permits;
00d3b7a4	187
be080a6f DH	188	/* If this set of permits is now wrong, clear the permits
	189	* pointer so that no one tries to use the stale information.
	190	*/
	191	if (changed) {
	192	spin_lock(&vnode->lock);
	193	if (permits != rcu_access_pointer(vnode->permit_cache))
	194	goto someone_else_changed_it_unlock;
	195	RCU_INIT_POINTER(vnode->permit_cache, NULL);
	196	spin_unlock(&vnode->lock);
	197
	198	afs_put_permits(permits);
	199	permits = NULL;
	200	size = 0;
	201	}
00d3b7a4 DH	202	}
00d3b7a4 DH	203
f642404a	204	if (afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)))
be080a6f	205	goto someone_else_changed_it;
00d3b7a4	206
be080a6f DH	207	/* We need a ref on any permits list we want to copy as we'll have to
	208	* drop the lock to do memory allocation.
	209	*/
fe342cf7	210	if (permits && !refcount_inc_not_zero(&permits->usage))
be080a6f	211	goto someone_else_changed_it;
be080a6f DH	212
	213	rcu_read_unlock();
	214
	215	/* Speculatively create a new list with the revised permission set. We
	216	* discard this if we find an extant match already in the hash, but
	217	* it's easier to compare with memcmp this way.
	218	*
	219	* We fill in the key pointers at this time, but we don't get the refs
	220	* yet.
	221	*/
	222	size++;
	223	new = kzalloc(sizeof(struct afs_permits) +
	224	sizeof(struct afs_permit) * size, GFP_NOFS);
	225	if (!new)
1bcab125	226	goto out_put;
be080a6f DH	227
	228	refcount_set(&new->usage, 1);
	229	new->nr_permits = size;
	230	i = j = 0;
	231	if (permits) {
	232	for (i = 0; i < permits->nr_permits; i++) {
	233	if (j == i && permits->permits[i].key > key) {
	234	new->permits[j].key = key;
	235	new->permits[j].access = caller_access;
	236	j++;
00d3b7a4	237	}
be080a6f DH	238	new->permits[j].key = permits->permits[i].key;
	239	new->permits[j].access = permits->permits[i].access;
	240	j++;
00d3b7a4 DH	241	}
	242	}
	243
be080a6f DH	244	if (j == i) {
	245	new->permits[j].key = key;
	246	new->permits[j].access = caller_access;
	247	}
	248
	249	afs_hash_permits(new);
	250
be080a6f DH	251	/* Now see if the permit list we want is actually already available */
	252	spin_lock(&afs_permits_lock);
	253
	254	hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
	255	if (xpermits->h != new->h \|\|
	256	xpermits->invalidated \|\|
	257	xpermits->nr_permits != new->nr_permits \|\|
	258	memcmp(xpermits->permits, new->permits,
	259	new->nr_permits * sizeof(struct afs_permit)) != 0)
	260	continue;
	261
	262	if (refcount_inc_not_zero(&xpermits->usage)) {
	263	replacement = xpermits;
	264	goto found;
	265	}
	266
	267	break;
	268	}
	269
	270	for (i = 0; i < new->nr_permits; i++)
	271	key_get(new->permits[i].key);
	272	hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
	273	replacement = new;
	274	new = NULL;
	275
	276	found:
	277	spin_unlock(&afs_permits_lock);
	278
	279	kfree(new);
	280
f642404a	281	rcu_read_lock();
be080a6f	282	spin_lock(&vnode->lock);
1bcab125	283	zap = rcu_access_pointer(vnode->permit_cache);
f642404a	284	if (!afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)) &&
1bcab125 DH	285	zap == permits)
	286	rcu_assign_pointer(vnode->permit_cache, replacement);
	287	else
	288	zap = replacement;
be080a6f	289	spin_unlock(&vnode->lock);
f642404a	290	rcu_read_unlock();
1bcab125 DH	291	afs_put_permits(zap);
1bcab125 DH	292	out_put:
be080a6f DH	293	afs_put_permits(permits);
	294	return;
	295
	296	someone_else_changed_it_unlock:
	297	spin_unlock(&vnode->lock);
	298	someone_else_changed_it:
	299	/* Someone else changed the cache under us - don't recheck at this
	300	* time.
	301	*/
fe342cf7	302	rcu_read_unlock();
be080a6f	303	return;
00d3b7a4 DH	304	}
00d3b7a4 DH	305
a0753c29 DH	306	static bool afs_check_permit_rcu(struct afs_vnode vnode, struct key key,
	307	afs_access_t *_access)
	308	{
	309	const struct afs_permits *permits;
	310	int i;
	311
	312	_enter("{%llx:%llu},%x",
	313	vnode->fid.vid, vnode->fid.vnode, key_serial(key));
	314
	315	/* check the permits to see if we've got one yet */
	316	if (key == vnode->volume->cell->anonymous_key) {
	317	*_access = vnode->status.anon_access;
	318	_leave(" = t [anon %x]", *_access);
	319	return true;
	320	}
	321
	322	permits = rcu_dereference(vnode->permit_cache);
	323	if (permits) {
	324	for (i = 0; i < permits->nr_permits; i++) {
	325	if (permits->permits[i].key < key)
	326	continue;
	327	if (permits->permits[i].key > key)
	328	break;
	329
	330	*_access = permits->permits[i].access;
	331	_leave(" = %u [perm %x]", !permits->invalidated, *_access);
	332	return !permits->invalidated;
	333	}
	334	}
	335
	336	_leave(" = f");
	337	return false;
	338	}
	339
00d3b7a4 DH	340	/*
	341	* check with the fileserver to see if the directory or parent directory is
	342	* permitted to be accessed with this authorisation, and if so, what access it
	343	* is granted
	344	*/
0fafdc9f DH	345	int afs_check_permit(struct afs_vnode vnode, struct key key,
0fafdc9f DH	346	afs_access_t *_access)
00d3b7a4 DH	347	{
00d3b7a4 DH	348	struct afs_permits *permits;
be080a6f DH	349	bool valid = false;
be080a6f DH	350	int i, ret;
00d3b7a4	351
3b6492df	352	_enter("{%llx:%llu},%x",
416351f2	353	vnode->fid.vid, vnode->fid.vnode, key_serial(key));
00d3b7a4	354
00d3b7a4	355	/* check the permits to see if we've got one yet */
be080a6f	356	if (key == vnode->volume->cell->anonymous_key) {
00d3b7a4	357	_debug("anon");
be080a6f	358	*_access = vnode->status.anon_access;
00d3b7a4 DH	359	valid = true;
00d3b7a4 DH	360	} else {
00d3b7a4	361	rcu_read_lock();
be080a6f	362	permits = rcu_dereference(vnode->permit_cache);
00d3b7a4	363	if (permits) {
be080a6f DH	364	for (i = 0; i < permits->nr_permits; i++) {
	365	if (permits->permits[i].key < key)
	366	continue;
	367	if (permits->permits[i].key > key)
00d3b7a4	368	break;
be080a6f DH	369
	370	*_access = permits->permits[i].access;
	371	valid = !permits->invalidated;
	372	break;
00d3b7a4 DH	373	}
	374	}
	375	rcu_read_unlock();
	376	}
	377
	378	if (!valid) {
be080a6f DH	379	/* Check the status on the file we're actually interested in
	380	* (the post-processing will cache the result).
	381	*/
00d3b7a4 DH	382	_debug("no valid permit");
00d3b7a4 DH	383
a58823ac	384	ret = afs_fetch_status(vnode, key, false, _access);
00d3b7a4	385	if (ret < 0) {
00d3b7a4 DH	386	*_access = 0;
	387	_leave(" = %d", ret);
	388	return ret;
	389	}
	390	}
	391
00d3b7a4 DH	392	_leave(" = 0 [access %x]", *_access);
	393	return 0;
	394	}
	395
	396	/*
	397	* check the permissions on an AFS file
	398	* - AFS ACLs are attached to directories only, and a file is controlled by its
	399	* parent directory's ACL
	400	*/
10556cb2	401	int afs_permission(struct inode *inode, int mask)
00d3b7a4 DH	402	{
00d3b7a4 DH	403	struct afs_vnode *vnode = AFS_FS_I(inode);
69759454	404	afs_access_t uninitialized_var(access);
00d3b7a4	405	struct key *key;
a0753c29	406	int ret = 0;
b74c79e9	407
3b6492df	408	_enter("{{%llx:%llu},%lx},%x,",
260a9803	409	vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
00d3b7a4	410
a0753c29 DH	411	if (mask & MAY_NOT_BLOCK) {
	412	key = afs_request_key_rcu(vnode->volume->cell);
	413	if (IS_ERR(key))
	414	return -ECHILD;
00d3b7a4	415
a0753c29 DH	416	ret = -ECHILD;
	417	if (!afs_check_validity(vnode) \|\|
	418	!afs_check_permit_rcu(vnode, key, &access))
	419	goto error;
	420	} else {
	421	key = afs_request_key(vnode->volume->cell);
	422	if (IS_ERR(key)) {
	423	_leave(" = %ld [key]", PTR_ERR(key));
	424	return PTR_ERR(key);
	425	}
260a9803	426
a0753c29 DH	427	ret = afs_validate(vnode, key);
	428	if (ret < 0)
	429	goto error;
	430
	431	/* check the permits to see if we've got one yet */
	432	ret = afs_check_permit(vnode, key, &access);
	433	if (ret < 0)
	434	goto error;
	435	}
00d3b7a4 DH	436
	437	/* interpret the access mask */
	438	_debug("REQ %x ACC %x on %s",
	439	mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
	440
a0753c29	441	ret = 0;
00d3b7a4	442	if (S_ISDIR(inode->i_mode)) {
378831e4	443	if (mask & (MAY_EXEC \| MAY_READ \| MAY_CHDIR)) {
00d3b7a4 DH	444	if (!(access & AFS_ACE_LOOKUP))
00d3b7a4 DH	445	goto permission_denied;
378831e4 DH	446	}
378831e4 DH	447	if (mask & MAY_WRITE) {
00d3b7a4	448	if (!(access & (AFS_ACE_DELETE \| /* rmdir, unlink, rename from */
fd249821	449	AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
00d3b7a4	450	goto permission_denied;
00d3b7a4 DH	451	}
	452	} else {
	453	if (!(access & AFS_ACE_LOOKUP))
	454	goto permission_denied;
627f4694 MD	455	if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
627f4694 MD	456	goto permission_denied;
00d3b7a4 DH	457	if (mask & (MAY_EXEC \| MAY_READ)) {
	458	if (!(access & AFS_ACE_READ))
	459	goto permission_denied;
627f4694 MD	460	if (!(inode->i_mode & S_IRUSR))
627f4694 MD	461	goto permission_denied;
00d3b7a4 DH	462	} else if (mask & MAY_WRITE) {
	463	if (!(access & AFS_ACE_WRITE))
	464	goto permission_denied;
627f4694 MD	465	if (!(inode->i_mode & S_IWUSR))
627f4694 MD	466	goto permission_denied;
00d3b7a4 DH	467	}
	468	}
	469
	470	key_put(key);
260a9803 DH	471	_leave(" = %d", ret);
260a9803 DH	472	return ret;
00d3b7a4 DH	473
00d3b7a4 DH	474	permission_denied:
260a9803 DH	475	ret = -EACCES;
260a9803 DH	476	error:
00d3b7a4	477	key_put(key);
260a9803 DH	478	_leave(" = %d", ret);
260a9803 DH	479	return ret;
00d3b7a4	480	}
be080a6f DH	481
	482	void __exit afs_clean_up_permit_cache(void)
	483	{
	484	int i;
	485
	486	for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
	487	WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
	488
	489	}