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KEYS: Fix __key_link_end() quota fixup on error 

Fix __key_link_end()'s attempt to fix up the quota if an error occurs.

There are two erroneous cases: Firstly, we always decrease the quota if
the preallocated replacement keyring needs cleaning up, irrespective of
whether or not we should (we may have replaced a pointer rather than
adding another pointer).

Secondly, we never clean up the quota if we added a pointer without the
keyring storage being extended (we allocate multiple pointers at a time,
even if we're not going to use them all immediately).

We handle this by setting the bottom bit of the preallocation pointer in
__key_link_begin() to indicate that the quota needs fixing up, which is
then passed to __key_link() (which clears the whole thing) and
__key_link_end().

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2011-01-25 16:34:28 +00:00 committed by Linus Torvalds
parent f5c66d70ac
commit ceb73c1204
4 changed files with 27 additions and 20 deletions
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6
security/keys/internal.h
View File

@ -87,13 +87,13 @@ extern void key_type_put(struct key_type *ktype);
extern int __key_link_begin(struct key *keyring,
const struct key_type *type,
const char *description,
struct keyring_list **_prealloc);
unsigned long *_prealloc);
extern int __key_link_check_live_key(struct key *keyring, struct key *key);
extern void __key_link(struct key *keyring, struct key *key,
struct keyring_list **_prealloc);
unsigned long *_prealloc);
extern void __key_link_end(struct key *keyring,
struct key_type *type,
struct keyring_list *prealloc);
unsigned long prealloc);
extern key_ref_t __keyring_search_one(key_ref_t keyring_ref,
const struct key_type *type,

8
security/keys/key.c
View File

@ -415,7 +415,7 @@ static int __key_instantiate_and_link(struct key *key,
size_t datalen,
struct key *keyring,
struct key *authkey,
struct keyring_list **_prealloc)
unsigned long *_prealloc)
{
int ret, awaken;
@ -481,7 +481,7 @@ int key_instantiate_and_link(struct key *key,
struct key *keyring,
struct key *authkey)
{
struct keyring_list *prealloc;
unsigned long prealloc;
int ret;
if (keyring) {
@ -526,7 +526,7 @@ int key_negate_and_link(struct key *key,
struct key *keyring,
struct key *authkey)
{
struct keyring_list *prealloc;
unsigned long prealloc;
struct timespec now;
int ret, awaken, link_ret = 0;
@ -814,7 +814,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
key_perm_t perm,
unsigned long flags)
{
struct keyring_list *prealloc;
unsigned long prealloc;
const struct cred *cred = current_cred();
struct key_type *ktype;
struct key *keyring, *key = NULL;

31
security/keys/keyring.c
View File

@ -25,6 +25,8 @@
(keyring)->payload.subscriptions, \
rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
#define KEY_LINK_FIXQUOTA 1UL
/*
* When plumbing the depths of the key tree, this sets a hard limit
* set on how deep we're willing to go.
@ -699,11 +701,11 @@ static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
* Preallocate memory so that a key can be linked into to a keyring.
*/
int __key_link_begin(struct key *keyring, const struct key_type *type,
const char *description,
struct keyring_list **_prealloc)
const char *description, unsigned long *_prealloc)
__acquires(&keyring->sem)
{
struct keyring_list *klist, *nklist;
unsigned long prealloc;
unsigned max;
size_t size;
int loop, ret;
@ -746,6 +748,7 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
/* note replacement slot */
klist->delkey = nklist->delkey = loop;
prealloc = (unsigned long)nklist;
goto done;
}
}
@ -760,6 +763,7 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
if (klist && klist->nkeys < klist->maxkeys) {
/* there's sufficient slack space to append directly */
nklist = NULL;
prealloc = KEY_LINK_FIXQUOTA;
} else {
/* grow the key list */
max = 4;
@ -794,8 +798,9 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
nklist->keys[nklist->delkey] = NULL;
}
prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
done:
*_prealloc = nklist;
*_prealloc = prealloc;
kleave(" = 0");
return 0;
@ -836,12 +841,12 @@ int __key_link_check_live_key(struct key *keyring, struct key *key)
* combination.
*/
void __key_link(struct key *keyring, struct key *key,
struct keyring_list **_prealloc)
unsigned long *_prealloc)
{
struct keyring_list *klist, *nklist;
nklist = *_prealloc;
*_prealloc = NULL;
nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
*_prealloc = 0;
kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
@ -881,20 +886,22 @@ void __key_link(struct key *keyring, struct key *key,
* Must be called with __key_link_begin() having being called.
*/
void __key_link_end(struct key *keyring, struct key_type *type,
struct keyring_list *prealloc)
unsigned long prealloc)
__releases(&keyring->sem)
{
BUG_ON(type == NULL);
BUG_ON(type->name == NULL);
kenter("%d,%s,%p", keyring->serial, type->name, prealloc);
kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
if (type == &key_type_keyring)
up_write(&keyring_serialise_link_sem);
if (prealloc) {
kfree(prealloc);
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
if (prealloc & KEY_LINK_FIXQUOTA)
key_payload_reserve(keyring,
keyring->datalen -
KEYQUOTA_LINK_BYTES);
kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
}
up_write(&keyring->sem);
}
@ -921,7 +928,7 @@ void __key_link_end(struct key *keyring, struct key_type *type,
*/
int key_link(struct key *keyring, struct key *key)
{
struct keyring_list *prealloc;
unsigned long prealloc;
int ret;
key_check(keyring);

2
security/keys/request_key.c
View File

@ -352,8 +352,8 @@ static int construct_alloc_key(struct key_type *type,
struct key_user *user,
struct key **_key)
{
struct keyring_list *prealloc;
const struct cred *cred = current_cred();
unsigned long prealloc;
struct key *key;
key_ref_t key_ref;
int ret;