[mirror_ubuntu-jammy-kernel.git] / security / keys / gc.c

/* Key garbage collector
 *
 * Copyright (C) 2009-2011 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/slab.h>
#include <linux/security.h>
#include <keys/keyring-type.h>
#include "internal.h"

/*
 * Delay between key revocation/expiry in seconds
 */
unsigned key_gc_delay = 5 * 60;

/*
 * Reaper for unused keys.
 */
static void key_garbage_collector(struct work_struct *work);
DECLARE_WORK(key_gc_work, key_garbage_collector);

/*
 * Reaper for links from keyrings to dead keys.
 */
static void key_gc_timer_func(struct timer_list *);
static DEFINE_TIMER(key_gc_timer, key_gc_timer_func);

static time64_t key_gc_next_run = TIME64_MAX;
static struct key_type *key_gc_dead_keytype;

static unsigned long key_gc_flags;
#define KEY_GC_KEY_EXPIRED	0	/* A key expired and needs unlinking */
#define KEY_GC_REAP_KEYTYPE	1	/* A keytype is being unregistered */
#define KEY_GC_REAPING_KEYTYPE	2	/* Cleared when keytype reaped */


/*
 * Any key whose type gets unregistered will be re-typed to this if it can't be
 * immediately unlinked.
 */
struct key_type key_type_dead = {
	.name = ".dead",
};

/*
 * Schedule a garbage collection run.
 * - time precision isn't particularly important
 */
void key_schedule_gc(time64_t gc_at)
{
	unsigned long expires;
	time64_t now = ktime_get_real_seconds();

	kenter("%lld", gc_at - now);

	if (gc_at <= now || test_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags)) {
		kdebug("IMMEDIATE");
		schedule_work(&key_gc_work);
	} else if (gc_at < key_gc_next_run) {
		kdebug("DEFERRED");
		key_gc_next_run = gc_at;
		expires = jiffies + (gc_at - now) * HZ;
		mod_timer(&key_gc_timer, expires);
	}
}

/*
 * Schedule a dead links collection run.
 */
void key_schedule_gc_links(void)
{
	set_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags);
	schedule_work(&key_gc_work);
}

/*
 * Some key's cleanup time was met after it expired, so we need to get the
 * reaper to go through a cycle finding expired keys.
 */
static void key_gc_timer_func(struct timer_list *unused)
{
	kenter("");
	key_gc_next_run = TIME64_MAX;
	key_schedule_gc_links();
}

/*
 * Reap keys of dead type.
 *
 * We use three flags to make sure we see three complete cycles of the garbage
 * collector: the first to mark keys of that type as being dead, the second to
 * collect dead links and the third to clean up the dead keys.  We have to be
 * careful as there may already be a cycle in progress.
 *
 * The caller must be holding key_types_sem.
 */
void key_gc_keytype(struct key_type *ktype)
{
	kenter("%s", ktype->name);

	key_gc_dead_keytype = ktype;
	set_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags);
	smp_mb();
	set_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags);

	kdebug("schedule");
	schedule_work(&key_gc_work);

	kdebug("sleep");
	wait_on_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE,
		    TASK_UNINTERRUPTIBLE);

	key_gc_dead_keytype = NULL;
	kleave("");
}

/*
 * Garbage collect a list of unreferenced, detached keys
 */
static noinline void key_gc_unused_keys(struct list_head *keys)
{
	while (!list_empty(keys)) {
		struct key *key =
			list_entry(keys->next, struct key, graveyard_link);
		short state = key->state;

		list_del(&key->graveyard_link);

		kdebug("- %u", key->serial);
		key_check(key);

		/* Throw away the key data if the key is instantiated */
		if (state == KEY_IS_POSITIVE && key->type->destroy)
			key->type->destroy(key);

		security_key_free(key);

		/* deal with the user's key tracking and quota */
		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
			spin_lock(&key->user->lock);
			key->user->qnkeys--;
			key->user->qnbytes -= key->quotalen;
			spin_unlock(&key->user->lock);
		}

		atomic_dec(&key->user->nkeys);
		if (state != KEY_IS_UNINSTANTIATED)
			atomic_dec(&key->user->nikeys);

		key_user_put(key->user);

		kfree(key->description);

		memzero_explicit(key, sizeof(*key));
		kmem_cache_free(key_jar, key);
	}
}

/*
 * Garbage collector for unused keys.
 *
 * This is done in process context so that we don't have to disable interrupts
 * all over the place.  key_put() schedules this rather than trying to do the
 * cleanup itself, which means key_put() doesn't have to sleep.
 */
static void key_garbage_collector(struct work_struct *work)
{
	static LIST_HEAD(graveyard);
	static u8 gc_state;		/* Internal persistent state */
#define KEY_GC_REAP_AGAIN	0x01	/* - Need another cycle */
#define KEY_GC_REAPING_LINKS	0x02	/* - We need to reap links */
#define KEY_GC_SET_TIMER	0x04	/* - We need to restart the timer */
#define KEY_GC_REAPING_DEAD_1	0x10	/* - We need to mark dead keys */
#define KEY_GC_REAPING_DEAD_2	0x20	/* - We need to reap dead key links */
#define KEY_GC_REAPING_DEAD_3	0x40	/* - We need to reap dead keys */
#define KEY_GC_FOUND_DEAD_KEY	0x80	/* - We found at least one dead key */

	struct rb_node *cursor;
	struct key *key;
	time64_t new_timer, limit;

	kenter("[%lx,%x]", key_gc_flags, gc_state);

	limit = ktime_get_real_seconds();
	if (limit > key_gc_delay)
		limit -= key_gc_delay;
	else
		limit = key_gc_delay;

	/* Work out what we're going to be doing in this pass */
	gc_state &= KEY_GC_REAPING_DEAD_1 | KEY_GC_REAPING_DEAD_2;
	gc_state <<= 1;
	if (test_and_clear_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags))
		gc_state |= KEY_GC_REAPING_LINKS | KEY_GC_SET_TIMER;

	if (test_and_clear_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags))
		gc_state |= KEY_GC_REAPING_DEAD_1;
	kdebug("new pass %x", gc_state);

	new_timer = TIME64_MAX;

	/* As only this function is permitted to remove things from the key
	 * serial tree, if cursor is non-NULL then it will always point to a
	 * valid node in the tree - even if lock got dropped.
	 */
	spin_lock(&key_serial_lock);
	cursor = rb_first(&key_serial_tree);

continue_scanning:
	while (cursor) {
		key = rb_entry(cursor, struct key, serial_node);
		cursor = rb_next(cursor);

		if (refcount_read(&key->usage) == 0)
			goto found_unreferenced_key;

		if (unlikely(gc_state & KEY_GC_REAPING_DEAD_1)) {
			if (key->type == key_gc_dead_keytype) {
				gc_state |= KEY_GC_FOUND_DEAD_KEY;
				set_bit(KEY_FLAG_DEAD, &key->flags);
				key->perm = 0;
				goto skip_dead_key;
			} else if (key->type == &key_type_keyring &&
				   key->restrict_link) {
				goto found_restricted_keyring;
			}
		}

		if (gc_state & KEY_GC_SET_TIMER) {
			if (key->expiry > limit && key->expiry < new_timer) {
				kdebug("will expire %x in %lld",
				       key_serial(key), key->expiry - limit);
				new_timer = key->expiry;
			}
		}

		if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2))
			if (key->type == key_gc_dead_keytype)
				gc_state |= KEY_GC_FOUND_DEAD_KEY;

		if ((gc_state & KEY_GC_REAPING_LINKS) ||
		    unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
			if (key->type == &key_type_keyring)
				goto found_keyring;
		}

		if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3))
			if (key->type == key_gc_dead_keytype)
				goto destroy_dead_key;

	skip_dead_key:
		if (spin_is_contended(&key_serial_lock) || need_resched())
			goto contended;
	}

contended:
	spin_unlock(&key_serial_lock);

maybe_resched:
	if (cursor) {
		cond_resched();
		spin_lock(&key_serial_lock);
		goto continue_scanning;
	}

	/* We've completed the pass.  Set the timer if we need to and queue a
	 * new cycle if necessary.  We keep executing cycles until we find one
	 * where we didn't reap any keys.
	 */
	kdebug("pass complete");

	if (gc_state & KEY_GC_SET_TIMER && new_timer != (time64_t)TIME64_MAX) {
		new_timer += key_gc_delay;
		key_schedule_gc(new_timer);
	}

	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2) ||
	    !list_empty(&graveyard)) {
		/* Make sure that all pending keyring payload destructions are
		 * fulfilled and that people aren't now looking at dead or
		 * dying keys that they don't have a reference upon or a link
		 * to.
		 */
		kdebug("gc sync");
		synchronize_rcu();
	}

	if (!list_empty(&graveyard)) {
		kdebug("gc keys");
		key_gc_unused_keys(&graveyard);
	}

	if (unlikely(gc_state & (KEY_GC_REAPING_DEAD_1 |
				 KEY_GC_REAPING_DEAD_2))) {
		if (!(gc_state & KEY_GC_FOUND_DEAD_KEY)) {
			/* No remaining dead keys: short circuit the remaining
			 * keytype reap cycles.
			 */
			kdebug("dead short");
			gc_state &= ~(KEY_GC_REAPING_DEAD_1 | KEY_GC_REAPING_DEAD_2);
			gc_state |= KEY_GC_REAPING_DEAD_3;
		} else {
			gc_state |= KEY_GC_REAP_AGAIN;
		}
	}

	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3)) {
		kdebug("dead wake");
		smp_mb();
		clear_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags);
		wake_up_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE);
	}

	if (gc_state & KEY_GC_REAP_AGAIN)
		schedule_work(&key_gc_work);
	kleave(" [end %x]", gc_state);
	return;

	/* We found an unreferenced key - once we've removed it from the tree,
	 * we can safely drop the lock.
	 */
found_unreferenced_key:
	kdebug("unrefd key %d", key->serial);
	rb_erase(&key->serial_node, &key_serial_tree);
	spin_unlock(&key_serial_lock);

	list_add_tail(&key->graveyard_link, &graveyard);
	gc_state |= KEY_GC_REAP_AGAIN;
	goto maybe_resched;

	/* We found a restricted keyring and need to update the restriction if
	 * it is associated with the dead key type.
	 */
found_restricted_keyring:
	spin_unlock(&key_serial_lock);
	keyring_restriction_gc(key, key_gc_dead_keytype);
	goto maybe_resched;

	/* We found a keyring and we need to check the payload for links to
	 * dead or expired keys.  We don't flag another reap immediately as we
	 * have to wait for the old payload to be destroyed by RCU before we
	 * can reap the keys to which it refers.
	 */
found_keyring:
	spin_unlock(&key_serial_lock);
	keyring_gc(key, limit);
	goto maybe_resched;

	/* We found a dead key that is still referenced.  Reset its type and
	 * destroy its payload with its semaphore held.
	 */
destroy_dead_key:
	spin_unlock(&key_serial_lock);
	kdebug("destroy key %d", key->serial);
	down_write(&key->sem);
	key->type = &key_type_dead;
	if (key_gc_dead_keytype->destroy)
		key_gc_dead_keytype->destroy(key);
	memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
	up_write(&key->sem);
	goto maybe_resched;
}
Commit	Line	Data
5d135440 DH	1	/* Key garbage collector
5d135440 DH	2	*
0c061b57	3	* Copyright (C) 2009-2011 Red Hat, Inc. All Rights Reserved.
5d135440 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 Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
8bc16dea DH	12	#include <linux/slab.h>
8bc16dea DH	13	#include <linux/security.h>
5d135440 DH	14	#include <keys/keyring-type.h>
	15	#include "internal.h"
	16
	17	/*
	18	* Delay between key revocation/expiry in seconds
	19	*/
	20	unsigned key_gc_delay = 5 * 60;
	21
	22	/*
8bc16dea DH	23	* Reaper for unused keys.
8bc16dea DH	24	*/
0c061b57 DH	25	static void key_garbage_collector(struct work_struct *work);
0c061b57 DH	26	DECLARE_WORK(key_gc_work, key_garbage_collector);
8bc16dea DH	27
	28	/*
	29	* Reaper for links from keyrings to dead keys.
5d135440	30	*/
24ed960a	31	static void key_gc_timer_func(struct timer_list *);
1d27e3e2	32	static DEFINE_TIMER(key_gc_timer, key_gc_timer_func);
0c061b57	33
074d5898	34	static time64_t key_gc_next_run = TIME64_MAX;
0c061b57 DH	35	static struct key_type *key_gc_dead_keytype;
	36
	37	static unsigned long key_gc_flags;
	38	#define KEY_GC_KEY_EXPIRED 0 /* A key expired and needs unlinking */
	39	#define KEY_GC_REAP_KEYTYPE 1 /* A keytype is being unregistered */
	40	#define KEY_GC_REAPING_KEYTYPE 2 /* Cleared when keytype reaped */
	41
	42
	43	/*
	44	* Any key whose type gets unregistered will be re-typed to this if it can't be
	45	* immediately unlinked.
	46	*/
	47	struct key_type key_type_dead = {
c1644fe0	48	.name = ".dead",
0c061b57	49	};
5d135440 DH	50
5d135440 DH	51	/*
973c9f4f DH	52	* Schedule a garbage collection run.
973c9f4f DH	53	* - time precision isn't particularly important
5d135440	54	*/
074d5898	55	void key_schedule_gc(time64_t gc_at)
5d135440 DH	56	{
5d135440 DH	57	unsigned long expires;
074d5898	58	time64_t now = ktime_get_real_seconds();
5d135440	59
074d5898	60	kenter("%lld", gc_at - now);
5d135440	61
0c061b57 DH	62	if (gc_at <= now \|\| test_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags)) {
0c061b57 DH	63	kdebug("IMMEDIATE");
3b07e9ca	64	schedule_work(&key_gc_work);
5d135440	65	} else if (gc_at < key_gc_next_run) {
0c061b57 DH	66	kdebug("DEFERRED");
0c061b57 DH	67	key_gc_next_run = gc_at;
5d135440 DH	68	expires = jiffies + (gc_at - now) * HZ;
	69	mod_timer(&key_gc_timer, expires);
	70	}
	71	}
	72
fd75815f DH	73	/*
	74	* Schedule a dead links collection run.
	75	*/
	76	void key_schedule_gc_links(void)
	77	{
	78	set_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags);
3b07e9ca	79	schedule_work(&key_gc_work);
fd75815f DH	80	}
fd75815f DH	81
5d135440	82	/*
0c061b57 DH	83	* Some key's cleanup time was met after it expired, so we need to get the
0c061b57 DH	84	* reaper to go through a cycle finding expired keys.
5d135440	85	*/
24ed960a	86	static void key_gc_timer_func(struct timer_list *unused)
5d135440 DH	87	{
5d135440 DH	88	kenter("");
074d5898	89	key_gc_next_run = TIME64_MAX;
fd75815f	90	key_schedule_gc_links();
5d135440 DH	91	}
5d135440 DH	92
0c061b57 DH	93	/*
	94	* Reap keys of dead type.
	95	*
	96	* We use three flags to make sure we see three complete cycles of the garbage
	97	* collector: the first to mark keys of that type as being dead, the second to
	98	* collect dead links and the third to clean up the dead keys. We have to be
	99	* careful as there may already be a cycle in progress.
	100	*
	101	* The caller must be holding key_types_sem.
	102	*/
	103	void key_gc_keytype(struct key_type *ktype)
	104	{
	105	kenter("%s", ktype->name);
	106
	107	key_gc_dead_keytype = ktype;
	108	set_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags);
	109	smp_mb();
	110	set_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags);
	111
	112	kdebug("schedule");
3b07e9ca	113	schedule_work(&key_gc_work);
0c061b57 DH	114
0c061b57 DH	115	kdebug("sleep");
74316201	116	wait_on_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE,
0c061b57 DH	117	TASK_UNINTERRUPTIBLE);
	118
	119	key_gc_dead_keytype = NULL;
	120	kleave("");
	121	}
	122
5d135440	123	/*
65d87fe6	124	* Garbage collect a list of unreferenced, detached keys
5d135440	125	*/
65d87fe6	126	static noinline void key_gc_unused_keys(struct list_head *keys)
5d135440	127	{
65d87fe6 DH	128	while (!list_empty(keys)) {
	129	struct key *key =
	130	list_entry(keys->next, struct key, graveyard_link);
363b02da DH	131	short state = key->state;
363b02da DH	132
65d87fe6 DH	133	list_del(&key->graveyard_link);
	134
	135	kdebug("- %u", key->serial);
	136	key_check(key);
	137
f05819df	138	/* Throw away the key data if the key is instantiated */
363b02da	139	if (state == KEY_IS_POSITIVE && key->type->destroy)
94c4554b DH	140	key->type->destroy(key);
94c4554b DH	141
65d87fe6 DH	142	security_key_free(key);
	143
	144	/* deal with the user's key tracking and quota */
	145	if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
	146	spin_lock(&key->user->lock);
	147	key->user->qnkeys--;
	148	key->user->qnbytes -= key->quotalen;
	149	spin_unlock(&key->user->lock);
	150	}
5d135440	151
65d87fe6	152	atomic_dec(&key->user->nkeys);
363b02da	153	if (state != KEY_IS_UNINSTANTIATED)
65d87fe6	154	atomic_dec(&key->user->nikeys);
5d135440	155
a3a87844 SL	156	key_user_put(key->user);
a3a87844 SL	157
65d87fe6	158	kfree(key->description);
5d135440	159
0620fddb	160	memzero_explicit(key, sizeof(*key));
65d87fe6 DH	161	kmem_cache_free(key_jar, key);
65d87fe6 DH	162	}
5d135440	163	}
8bc16dea DH	164
	165	/*
	166	* Garbage collector for unused keys.
	167	*
	168	* This is done in process context so that we don't have to disable interrupts
	169	* all over the place. key_put() schedules this rather than trying to do the
	170	* cleanup itself, which means key_put() doesn't have to sleep.
	171	*/
0c061b57	172	static void key_garbage_collector(struct work_struct *work)
8bc16dea	173	{
65d87fe6	174	static LIST_HEAD(graveyard);
0c061b57 DH	175	static u8 gc_state; /* Internal persistent state */
	176	#define KEY_GC_REAP_AGAIN 0x01 /* - Need another cycle */
	177	#define KEY_GC_REAPING_LINKS 0x02 /* - We need to reap links */
	178	#define KEY_GC_SET_TIMER 0x04 /* - We need to restart the timer */
	179	#define KEY_GC_REAPING_DEAD_1 0x10 /* - We need to mark dead keys */
	180	#define KEY_GC_REAPING_DEAD_2 0x20 /* - We need to reap dead key links */
	181	#define KEY_GC_REAPING_DEAD_3 0x40 /* - We need to reap dead keys */
	182	#define KEY_GC_FOUND_DEAD_KEY 0x80 /* - We found at least one dead key */
	183
	184	struct rb_node *cursor;
8bc16dea	185	struct key *key;
074d5898	186	time64_t new_timer, limit;
0c061b57 DH	187
	188	kenter("[%lx,%x]", key_gc_flags, gc_state);
	189
074d5898	190	limit = ktime_get_real_seconds();
0c061b57 DH	191	if (limit > key_gc_delay)
	192	limit -= key_gc_delay;
	193	else
	194	limit = key_gc_delay;
	195
	196	/* Work out what we're going to be doing in this pass */
	197	gc_state &= KEY_GC_REAPING_DEAD_1 \| KEY_GC_REAPING_DEAD_2;
	198	gc_state <<= 1;
	199	if (test_and_clear_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags))
	200	gc_state \|= KEY_GC_REAPING_LINKS \| KEY_GC_SET_TIMER;
	201
	202	if (test_and_clear_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags))
	203	gc_state \|= KEY_GC_REAPING_DEAD_1;
	204	kdebug("new pass %x", gc_state);
	205
074d5898	206	new_timer = TIME64_MAX;
8bc16dea	207
0c061b57 DH	208	/* As only this function is permitted to remove things from the key
	209	* serial tree, if cursor is non-NULL then it will always point to a
	210	* valid node in the tree - even if lock got dropped.
	211	*/
8bc16dea	212	spin_lock(&key_serial_lock);
0c061b57	213	cursor = rb_first(&key_serial_tree);
8bc16dea	214
0c061b57 DH	215	continue_scanning:
	216	while (cursor) {
	217	key = rb_entry(cursor, struct key, serial_node);
	218	cursor = rb_next(cursor);
8bc16dea	219
fff29291	220	if (refcount_read(&key->usage) == 0)
0c061b57 DH	221	goto found_unreferenced_key;
	222
	223	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_1)) {
	224	if (key->type == key_gc_dead_keytype) {
	225	gc_state \|= KEY_GC_FOUND_DEAD_KEY;
	226	set_bit(KEY_FLAG_DEAD, &key->flags);
	227	key->perm = 0;
	228	goto skip_dead_key;
2b6aa412 MM	229	} else if (key->type == &key_type_keyring &&
	230	key->restrict_link) {
	231	goto found_restricted_keyring;
0c061b57 DH	232	}
	233	}
	234
	235	if (gc_state & KEY_GC_SET_TIMER) {
	236	if (key->expiry > limit && key->expiry < new_timer) {
074d5898	237	kdebug("will expire %x in %lld",
0c061b57 DH	238	key_serial(key), key->expiry - limit);
	239	new_timer = key->expiry;
	240	}
	241	}
	242
	243	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2))
	244	if (key->type == key_gc_dead_keytype)
	245	gc_state \|= KEY_GC_FOUND_DEAD_KEY;
	246
	247	if ((gc_state & KEY_GC_REAPING_LINKS) \|\|
	248	unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
	249	if (key->type == &key_type_keyring)
	250	goto found_keyring;
	251	}
	252
	253	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3))
	254	if (key->type == key_gc_dead_keytype)
	255	goto destroy_dead_key;
	256
	257	skip_dead_key:
	258	if (spin_is_contended(&key_serial_lock) \|\| need_resched())
	259	goto contended;
8bc16dea DH	260	}
8bc16dea DH	261
0c061b57	262	contended:
8bc16dea	263	spin_unlock(&key_serial_lock);
8bc16dea	264
0c061b57 DH	265	maybe_resched:
	266	if (cursor) {
	267	cond_resched();
	268	spin_lock(&key_serial_lock);
	269	goto continue_scanning;
	270	}
8bc16dea	271
0c061b57 DH	272	/* We've completed the pass. Set the timer if we need to and queue a
	273	* new cycle if necessary. We keep executing cycles until we find one
	274	* where we didn't reap any keys.
	275	*/
	276	kdebug("pass complete");
8bc16dea	277
074d5898	278	if (gc_state & KEY_GC_SET_TIMER && new_timer != (time64_t)TIME64_MAX) {
0c061b57 DH	279	new_timer += key_gc_delay;
	280	key_schedule_gc(new_timer);
	281	}
8bc16dea	282
65d87fe6 DH	283	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2) \|\|
	284	!list_empty(&graveyard)) {
	285	/* Make sure that all pending keyring payload destructions are
	286	* fulfilled and that people aren't now looking at dead or
	287	* dying keys that they don't have a reference upon or a link
	288	* to.
0c061b57	289	*/
65d87fe6	290	kdebug("gc sync");
0c061b57	291	synchronize_rcu();
8bc16dea DH	292	}
8bc16dea DH	293
65d87fe6 DH	294	if (!list_empty(&graveyard)) {
	295	kdebug("gc keys");
	296	key_gc_unused_keys(&graveyard);
	297	}
	298
0c061b57 DH	299	if (unlikely(gc_state & (KEY_GC_REAPING_DEAD_1 \|
	300	KEY_GC_REAPING_DEAD_2))) {
	301	if (!(gc_state & KEY_GC_FOUND_DEAD_KEY)) {
	302	/* No remaining dead keys: short circuit the remaining
	303	* keytype reap cycles.
	304	*/
	305	kdebug("dead short");
	306	gc_state &= ~(KEY_GC_REAPING_DEAD_1 \| KEY_GC_REAPING_DEAD_2);
	307	gc_state \|= KEY_GC_REAPING_DEAD_3;
	308	} else {
	309	gc_state \|= KEY_GC_REAP_AGAIN;
	310	}
	311	}
8bc16dea	312
0c061b57 DH	313	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3)) {
	314	kdebug("dead wake");
	315	smp_mb();
	316	clear_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags);
	317	wake_up_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE);
	318	}
8bc16dea	319
0c061b57	320	if (gc_state & KEY_GC_REAP_AGAIN)
3b07e9ca	321	schedule_work(&key_gc_work);
0c061b57 DH	322	kleave(" [end %x]", gc_state);
0c061b57 DH	323	return;
8bc16dea	324
0c061b57 DH	325	/* We found an unreferenced key - once we've removed it from the tree,
	326	* we can safely drop the lock.
	327	*/
	328	found_unreferenced_key:
	329	kdebug("unrefd key %d", key->serial);
	330	rb_erase(&key->serial_node, &key_serial_tree);
	331	spin_unlock(&key_serial_lock);
8bc16dea	332
65d87fe6	333	list_add_tail(&key->graveyard_link, &graveyard);
0c061b57 DH	334	gc_state \|= KEY_GC_REAP_AGAIN;
0c061b57 DH	335	goto maybe_resched;
8bc16dea	336
2b6aa412 MM	337	/* We found a restricted keyring and need to update the restriction if
	338	* it is associated with the dead key type.
	339	*/
	340	found_restricted_keyring:
	341	spin_unlock(&key_serial_lock);
	342	keyring_restriction_gc(key, key_gc_dead_keytype);
	343	goto maybe_resched;
	344
0c061b57 DH	345	/* We found a keyring and we need to check the payload for links to
	346	* dead or expired keys. We don't flag another reap immediately as we
	347	* have to wait for the old payload to be destroyed by RCU before we
	348	* can reap the keys to which it refers.
	349	*/
	350	found_keyring:
	351	spin_unlock(&key_serial_lock);
62fe3182	352	keyring_gc(key, limit);
0c061b57 DH	353	goto maybe_resched;
	354
	355	/* We found a dead key that is still referenced. Reset its type and
	356	* destroy its payload with its semaphore held.
	357	*/
	358	destroy_dead_key:
	359	spin_unlock(&key_serial_lock);
	360	kdebug("destroy key %d", key->serial);
	361	down_write(&key->sem);
	362	key->type = &key_type_dead;
	363	if (key_gc_dead_keytype->destroy)
	364	key_gc_dead_keytype->destroy(key);
	365	memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
	366	up_write(&key->sem);
	367	goto maybe_resched;
8bc16dea	368	}