mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![David Howells](/assets/img/avatar_default.png)
Fix up comments in the key management code. No functional changes. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
222 lines
5.2 KiB
C
222 lines
5.2 KiB
C
/* Key garbage collector
|
|
*
|
|
* Copyright (C) 2009 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 <keys/keyring-type.h>
|
|
#include "internal.h"
|
|
|
|
/*
|
|
* Delay between key revocation/expiry in seconds
|
|
*/
|
|
unsigned key_gc_delay = 5 * 60;
|
|
|
|
/*
|
|
* Reaper
|
|
*/
|
|
static void key_gc_timer_func(unsigned long);
|
|
static void key_garbage_collector(struct work_struct *);
|
|
static DEFINE_TIMER(key_gc_timer, key_gc_timer_func, 0, 0);
|
|
static DECLARE_WORK(key_gc_work, key_garbage_collector);
|
|
static key_serial_t key_gc_cursor; /* the last key the gc considered */
|
|
static bool key_gc_again;
|
|
static unsigned long key_gc_executing;
|
|
static time_t key_gc_next_run = LONG_MAX;
|
|
static time_t key_gc_new_timer;
|
|
|
|
/*
|
|
* 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) {
|
|
schedule_work(&key_gc_work);
|
|
} else if (gc_at < key_gc_next_run) {
|
|
expires = jiffies + (gc_at - now) * HZ;
|
|
mod_timer(&key_gc_timer, expires);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The garbage collector timer kicked off
|
|
*/
|
|
static void key_gc_timer_func(unsigned long data)
|
|
{
|
|
kenter("");
|
|
key_gc_next_run = LONG_MAX;
|
|
schedule_work(&key_gc_work);
|
|
}
|
|
|
|
/*
|
|
* Garbage collect pointers from a keyring.
|
|
*
|
|
* Return true if we altered the keyring.
|
|
*/
|
|
static bool key_gc_keyring(struct key *keyring, time_t limit)
|
|
__releases(key_serial_lock)
|
|
{
|
|
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;
|
|
|
|
for (loop = klist->nkeys - 1; 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(" = false");
|
|
return false;
|
|
|
|
do_gc:
|
|
rcu_read_unlock();
|
|
key_gc_cursor = keyring->serial;
|
|
key_get(keyring);
|
|
spin_unlock(&key_serial_lock);
|
|
keyring_gc(keyring, limit);
|
|
key_put(keyring);
|
|
kleave(" = true");
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Garbage collector for keys. This involves scanning the keyrings for dead,
|
|
* expired and revoked keys that have overstayed their welcome
|
|
*/
|
|
static void key_garbage_collector(struct work_struct *work)
|
|
{
|
|
struct rb_node *rb;
|
|
key_serial_t cursor;
|
|
struct key *key, *xkey;
|
|
time_t new_timer = LONG_MAX, limit, now;
|
|
|
|
now = current_kernel_time().tv_sec;
|
|
kenter("[%x,%ld]", key_gc_cursor, key_gc_new_timer - now);
|
|
|
|
if (test_and_set_bit(0, &key_gc_executing)) {
|
|
key_schedule_gc(current_kernel_time().tv_sec + 1);
|
|
kleave(" [busy; deferring]");
|
|
return;
|
|
}
|
|
|
|
limit = now;
|
|
if (limit > key_gc_delay)
|
|
limit -= key_gc_delay;
|
|
else
|
|
limit = key_gc_delay;
|
|
|
|
spin_lock(&key_serial_lock);
|
|
|
|
if (unlikely(RB_EMPTY_ROOT(&key_serial_tree))) {
|
|
spin_unlock(&key_serial_lock);
|
|
clear_bit(0, &key_gc_executing);
|
|
return;
|
|
}
|
|
|
|
cursor = key_gc_cursor;
|
|
if (cursor < 0)
|
|
cursor = 0;
|
|
if (cursor > 0)
|
|
new_timer = key_gc_new_timer;
|
|
else
|
|
key_gc_again = false;
|
|
|
|
/* find the first key above the cursor */
|
|
key = NULL;
|
|
rb = key_serial_tree.rb_node;
|
|
while (rb) {
|
|
xkey = rb_entry(rb, struct key, serial_node);
|
|
if (cursor < xkey->serial) {
|
|
key = xkey;
|
|
rb = rb->rb_left;
|
|
} else if (cursor > xkey->serial) {
|
|
rb = rb->rb_right;
|
|
} else {
|
|
rb = rb_next(rb);
|
|
if (!rb)
|
|
goto reached_the_end;
|
|
key = rb_entry(rb, struct key, serial_node);
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!key)
|
|
goto reached_the_end;
|
|
|
|
/* trawl through the keys looking for keyrings */
|
|
for (;;) {
|
|
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 (key->type == &key_type_keyring &&
|
|
key_gc_keyring(key, limit))
|
|
/* the gc had to release our lock so that the keyring
|
|
* could be modified, so we have to get it again */
|
|
goto gc_released_our_lock;
|
|
|
|
rb = rb_next(&key->serial_node);
|
|
if (!rb)
|
|
goto reached_the_end;
|
|
key = rb_entry(rb, struct key, serial_node);
|
|
}
|
|
|
|
gc_released_our_lock:
|
|
kdebug("gc_released_our_lock");
|
|
key_gc_new_timer = new_timer;
|
|
key_gc_again = true;
|
|
clear_bit(0, &key_gc_executing);
|
|
schedule_work(&key_gc_work);
|
|
kleave(" [continue]");
|
|
return;
|
|
|
|
/* when we reach the end of the run, we set the timer for the next one */
|
|
reached_the_end:
|
|
kdebug("reached_the_end");
|
|
spin_unlock(&key_serial_lock);
|
|
key_gc_new_timer = new_timer;
|
|
key_gc_cursor = 0;
|
|
clear_bit(0, &key_gc_executing);
|
|
|
|
if (key_gc_again) {
|
|
/* there may have been a key that expired whilst we were
|
|
* scanning, so if we discarded any links we should do another
|
|
* scan */
|
|
new_timer = now + 1;
|
|
key_schedule_gc(new_timer);
|
|
} else if (new_timer < LONG_MAX) {
|
|
new_timer += key_gc_delay;
|
|
key_schedule_gc(new_timer);
|
|
}
|
|
kleave(" [end]");
|
|
}
|