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KEYS: Define a __key_get() wrapper to use rather than atomic_inc()

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Define a __key_get() wrapper to use rather than atomic_inc() on the key usage
count as this makes it easier to hook in refcount error debugging.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2013-09-24 10:35:16 +01:00
parent d0a059cac6
commit ccc3e6d9c9
5 changed files with 27 additions and 20 deletions
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13
Documentation/security/keys.txt
View file

@ -960,14 +960,17 @@ payload contents" for more information.
the argument will not be parsed.
(*) Extra references can be made to a key by calling the following function:
(*) Extra references can be made to a key by calling one of the following
functions:
struct key *__key_get(struct key *key);
struct key *key_get(struct key *key);
These need to be disposed of by calling key_put() when they've been
finished with. The key pointer passed in will be returned. If the pointer
is NULL or CONFIG_KEYS is not set then the key will not be dereferenced and
no increment will take place.
Keys so references will need to be disposed of by calling key_put() when
they've been finished with. The key pointer passed in will be returned.
In the case of key_get(), if the pointer is NULL or CONFIG_KEYS is not set
then the key will not be dereferenced and no increment will take place.
(*) A key's serial number can be obtained by calling:

10
include/linux/key.h
View file

@ -219,11 +219,15 @@ extern void key_revoke(struct key *key);
extern void key_invalidate(struct key *key);
extern void key_put(struct key *key);
static inline struct key *__key_get(struct key *key)
{
atomic_inc(&key->usage);
return key;
}
static inline struct key *key_get(struct key *key)
{
if (key)
atomic_inc(&key->usage);
return key;
return key ? __key_get(key) : key;
}
static inline void key_ref_put(key_ref_t key_ref)

2
security/keys/key.c
View file

@ -644,7 +644,7 @@ struct key *key_lookup(key_serial_t id)
/* this races with key_put(), but that doesn't matter since key_put()
* doesn't actually change the key
*/
atomic_inc(&key->usage);
__key_get(key);
error:
spin_unlock(&key_serial_lock);

6
security/keys/keyring.c
View file

@ -479,7 +479,7 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref,
/* we found a viable match */
found:
atomic_inc(&key->usage);
__key_get(key);
key->last_used_at = ctx->now.tv_sec;
keyring->last_used_at = ctx->now.tv_sec;
while (sp > 0)
@ -573,7 +573,7 @@ key_ref_t __keyring_search_one(key_ref_t keyring_ref,
return ERR_PTR(-ENOKEY);
found:
atomic_inc(&key->usage);
__key_get(key);
keyring->last_used_at = key->last_used_at =
current_kernel_time().tv_sec;
rcu_read_unlock();
@ -909,7 +909,7 @@ void __key_link(struct key *keyring, struct key *key,
klist = rcu_dereference_locked_keyring(keyring);
atomic_inc(&key->usage);
__key_get(key);
keyring->last_used_at = key->last_used_at =
current_kernel_time().tv_sec;

16
security/keys/process_keys.c
View file

@ -235,7 +235,7 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
if (IS_ERR(keyring))
return PTR_ERR(keyring);
} else {
atomic_inc(&keyring->usage);
__key_get(keyring);
}
/* install the keyring */
@ -544,7 +544,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
}
key = ctx.cred->thread_keyring;
atomic_inc(&key->usage);
__key_get(key);
key_ref = make_key_ref(key, 1);
break;
@ -562,7 +562,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
}
key = ctx.cred->process_keyring;
atomic_inc(&key->usage);
__key_get(key);
key_ref = make_key_ref(key, 1);
break;
@ -593,7 +593,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
rcu_read_lock();
key = rcu_dereference(ctx.cred->session_keyring);
atomic_inc(&key->usage);
__key_get(key);
rcu_read_unlock();
key_ref = make_key_ref(key, 1);
break;
@ -606,7 +606,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
}
key = ctx.cred->user->uid_keyring;
atomic_inc(&key->usage);
__key_get(key);
key_ref = make_key_ref(key, 1);
break;
@ -618,7 +618,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
}
key = ctx.cred->user->session_keyring;
atomic_inc(&key->usage);
__key_get(key);
key_ref = make_key_ref(key, 1);
break;
@ -632,7 +632,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
if (!key)
goto error;
atomic_inc(&key->usage);
__key_get(key);
key_ref = make_key_ref(key, 1);
break;
@ -648,7 +648,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
} else {
rka = ctx.cred->request_key_auth->payload.data;
key = rka->dest_keyring;
atomic_inc(&key->usage);
__key_get(key);
}
up_read(&ctx.cred->request_key_auth->sem);
if (!key)