[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/security/keys/gc.c b/ap/os/linux/linux-3.4.x/security/keys/gc.c
new file mode 100644
index 0000000..87632bd
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/security/keys/gc.c
@@ -0,0 +1,390 @@
+/* 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/module.h>
+#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(unsigned long);
+static DEFINE_TIMER(key_gc_timer, key_gc_timer_func, 0, 0);
+
+static time_t key_gc_next_run = LONG_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(time_t gc_at)
+{
+ unsigned long expires;
+ time_t now = current_kernel_time().tv_sec;
+
+ kenter("%ld", gc_at - now);
+
+ if (gc_at <= now || test_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags)) {
+ kdebug("IMMEDIATE");
+ queue_work(system_nrt_wq, &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);
+ }
+}
+
+/*
+ * 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(unsigned long data)
+{
+ kenter("");
+ key_gc_next_run = LONG_MAX;
+ set_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags);
+ queue_work(system_nrt_wq, &key_gc_work);
+}
+
+/*
+ * wait_on_bit() sleep function for uninterruptible waiting
+ */
+static int key_gc_wait_bit(void *flags)
+{
+ schedule();
+ return 0;
+}
+
+/*
+ * 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");
+ queue_work(system_nrt_wq, &key_gc_work);
+
+ kdebug("sleep");
+ wait_on_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE, key_gc_wait_bit,
+ TASK_UNINTERRUPTIBLE);
+
+ key_gc_dead_keytype = NULL;
+ kleave("");
+}
+
+/*
+ * Garbage collect pointers from a keyring.
+ *
+ * Not called with any locks held. The keyring's key struct will not be
+ * deallocated under us as only our caller may deallocate it.
+ */
+static void key_gc_keyring(struct key *keyring, time_t limit)
+{
+ struct keyring_list *klist;
+ struct key *key;
+ int loop;
+
+ kenter("%x", key_serial(keyring));
+
+ if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
+ goto dont_gc;
+
+ /* scan the keyring looking for dead keys */
+ rcu_read_lock();
+ klist = rcu_dereference(keyring->payload.subscriptions);
+ if (!klist)
+ goto unlock_dont_gc;
+
+ loop = klist->nkeys;
+ smp_rmb();
+ for (loop--; loop >= 0; loop--) {
+ key = klist->keys[loop];
+ if (test_bit(KEY_FLAG_DEAD, &key->flags) ||
+ (key->expiry > 0 && key->expiry <= limit))
+ goto do_gc;
+ }
+
+unlock_dont_gc:
+ rcu_read_unlock();
+dont_gc:
+ kleave(" [no gc]");
+ return;
+
+do_gc:
+ rcu_read_unlock();
+
+ keyring_gc(keyring, limit);
+ kleave(" [gc]");
+}
+
+/*
+ * Garbage collect an unreferenced, detached key
+ */
+static noinline void key_gc_unused_key(struct key *key)
+{
+ key_check(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 (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
+ atomic_dec(&key->user->nikeys);
+
+ /* now throw away the key memory */
+ if (key->type->destroy)
+ key->type->destroy(key);
+
+ key_user_put(key->user);
+
+ kfree(key->description);
+
+#ifdef KEY_DEBUGGING
+ key->magic = KEY_DEBUG_MAGIC_X;
+#endif
+ 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 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;
+ time_t new_timer, limit;
+
+ kenter("[%lx,%x]", key_gc_flags, gc_state);
+
+ limit = current_kernel_time().tv_sec;
+ 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 = LONG_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 (atomic_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;
+ }
+ }
+
+ if (gc_state & KEY_GC_SET_TIMER) {
+ if (key->expiry > limit && key->expiry < new_timer) {
+ kdebug("will expire %x in %ld",
+ 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 != (time_t)LONG_MAX) {
+ new_timer += key_gc_delay;
+ key_schedule_gc(new_timer);
+ }
+
+ if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
+ /* Make sure everyone revalidates their keys if we marked a
+ * bunch as being dead and make sure all keyring ex-payloads
+ * are destroyed.
+ */
+ kdebug("dead sync");
+ synchronize_rcu();
+ }
+
+ 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)
+ queue_work(system_nrt_wq, &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);
+
+ key_gc_unused_key(key);
+ gc_state |= KEY_GC_REAP_AGAIN;
+ 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);
+ kdebug("scan keyring %d", key->serial);
+ key_gc_keyring(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;
+}