security, keys: convert key_user.usage from atomic_t to refcount_t
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
diff --git a/security/keys/internal.h b/security/keys/internal.h
index a2f4c0a..6bee06a 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -17,6 +17,7 @@
#include <linux/key-type.h>
#include <linux/task_work.h>
#include <linux/keyctl.h>
+#include <linux/refcount.h>
struct iovec;
@@ -53,7 +54,7 @@
struct rb_node node;
struct mutex cons_lock; /* construction initiation lock */
spinlock_t lock;
- atomic_t usage; /* for accessing qnkeys & qnbytes */
+ refcount_t usage; /* for accessing qnkeys & qnbytes */
atomic_t nkeys; /* number of keys */
atomic_t nikeys; /* number of instantiated keys */
kuid_t uid;
diff --git a/security/keys/key.c b/security/keys/key.c
index ff92443..b4958b3 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -93,7 +93,7 @@
/* if we get here, then the user record still hadn't appeared on the
* second pass - so we use the candidate record */
- atomic_set(&candidate->usage, 1);
+ refcount_set(&candidate->usage, 1);
atomic_set(&candidate->nkeys, 0);
atomic_set(&candidate->nikeys, 0);
candidate->uid = uid;
@@ -110,7 +110,7 @@
/* okay - we found a user record for this UID */
found:
- atomic_inc(&user->usage);
+ refcount_inc(&user->usage);
spin_unlock(&key_user_lock);
kfree(candidate);
out:
@@ -122,7 +122,7 @@
*/
void key_user_put(struct key_user *user)
{
- if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
+ if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
rb_erase(&user->node, &key_user_tree);
spin_unlock(&key_user_lock);
diff --git a/security/keys/proc.c b/security/keys/proc.c
index 69199f1..bf08d02 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -340,7 +340,7 @@
seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
from_kuid_munged(seq_user_ns(m), user->uid),
- atomic_read(&user->usage),
+ refcount_read(&user->usage),
atomic_read(&user->nkeys),
atomic_read(&user->nikeys),
user->qnkeys,
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index b6fdd22..44451af 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -30,7 +30,7 @@
/* The root user's tracking struct */
struct key_user root_key_user = {
- .usage = ATOMIC_INIT(3),
+ .usage = REFCOUNT_INIT(3),
.cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock),
.lock = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
.nkeys = ATOMIC_INIT(2),