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KEYS: Use RCU dereference wrappers in keyring key type code 

The keyring key type code should use RCU dereference wrappers, even when it
holds the keyring's key semaphore.

Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
David Howells 2010-04-30 14:32:18 +01:00 committed by James Morris
parent cea7daa358
commit f0641cba77
1 changed files with 13 additions and 10 deletions
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23
security/keys/keyring.c
View File

@ -20,6 +20,11 @@
#include <asm/uaccess.h>
#include "internal.h"
#define rcu_dereference_locked_keyring(keyring) \
(rcu_dereference_protected( \
(keyring)->payload.subscriptions, \
rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
/*
* when plumbing the depths of the key tree, this sets a hard limit set on how
* deep we're willing to go
@ -201,8 +206,7 @@ static long keyring_read(const struct key *keyring,
int loop, ret;
ret = 0;
klist = keyring->payload.subscriptions;
klist = rcu_dereference_locked_keyring(keyring);
if (klist) {
/* calculate how much data we could return */
qty = klist->nkeys * sizeof(key_serial_t);
@ -720,8 +724,7 @@ int __key_link(struct key *keyring, struct key *key)
}
/* see if there's a matching key we can displace */
klist = keyring->payload.subscriptions;
klist = rcu_dereference_locked_keyring(keyring);
if (klist && klist->nkeys > 0) {
struct key_type *type = key->type;
@ -765,8 +768,6 @@ int __key_link(struct key *keyring, struct key *key)
if (ret < 0)
goto error2;
klist = keyring->payload.subscriptions;
if (klist && klist->nkeys < klist->maxkeys) {
/* there's sufficient slack space to add directly */
atomic_inc(&key->usage);
@ -868,7 +869,7 @@ int key_unlink(struct key *keyring, struct key *key)
down_write(&keyring->sem);
klist = keyring->payload.subscriptions;
klist = rcu_dereference_locked_keyring(keyring);
if (klist) {
/* search the keyring for the key */
for (loop = 0; loop < klist->nkeys; loop++)
@ -959,7 +960,7 @@ int keyring_clear(struct key *keyring)
/* detach the pointer block with the locks held */
down_write(&keyring->sem);
klist = keyring->payload.subscriptions;
klist = rcu_dereference_locked_keyring(keyring);
if (klist) {
/* adjust the quota */
key_payload_reserve(keyring,
@ -991,7 +992,9 @@ EXPORT_SYMBOL(keyring_clear);
*/
static void keyring_revoke(struct key *keyring)
{
struct keyring_list *klist = keyring->payload.subscriptions;
struct keyring_list *klist;
klist = rcu_dereference_locked_keyring(keyring);
/* adjust the quota */
key_payload_reserve(keyring, 0);
@ -1025,7 +1028,7 @@ void keyring_gc(struct key *keyring, time_t limit)
down_write(&keyring->sem);
klist = keyring->payload.subscriptions;
klist = rcu_dereference_locked_keyring(keyring);
if (!klist)
goto no_klist;