1 files changed, 30 insertions, 27 deletions

diff --git a/security/keys/key.c b/security/keys/key.c
index 51f851557389..80de8c3e9cc3 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -11,15 +11,16 @@
 
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/poison.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/security.h>
 #include <linux/workqueue.h>
+#include <linux/random.h>
 #include <linux/err.h>
 #include "internal.h"
 
 static kmem_cache_t     *key_jar;
-static key_serial_t     key_serial_next = 3;
 struct rb_root          key_serial_tree; /* tree of keys indexed by serial */
 DEFINE_SPINLOCK(key_serial_lock);
 
@@ -169,22 +170,23 @@ static void __init __key_insert_serial(struct key *key)
 /*****************************************************************************/
 /*
  * assign a key the next unique serial number
- * - we work through all the serial numbers between 2 and 2^31-1 in turn and
- *   then wrap
+ * - these are assigned randomly to avoid security issues through covert
+ *   channel problems
  */
 static inline void key_alloc_serial(struct key *key)
 {
         struct rb_node *parent, **p;
         struct key *xkey;
 
-        spin_lock(&key_serial_lock);
-
-        /* propose a likely serial number and look for a hole for it in the
+        /* propose a random serial number and look for a hole for it in the
          * serial number tree */
-        key->serial = key_serial_next;
-        if (key->serial < 3)
-                key->serial = 3;
-        key_serial_next = key->serial + 1;
+        do {
+                get_random_bytes(&key->serial, sizeof(key->serial));
+
+                key->serial >>= 1; /* negative numbers are not permitted */
+        } while (key->serial < 3);
+
+        spin_lock(&key_serial_lock);
 
         parent = NULL;
         p = &key_serial_tree.rb_node;
@@ -204,12 +206,11 @@ static inline void key_alloc_serial(struct key *key)
 
         /* we found a key with the proposed serial number - walk the tree from
          * that point looking for the next unused serial number */
- serial_exists:
+serial_exists:
         for (;;) {
-                key->serial = key_serial_next;
+                key->serial++;
                 if (key->serial < 2)
                         key->serial = 2;
-                key_serial_next = key->serial + 1;
 
                 if (!rb_parent(parent))
                         p = &key_serial_tree.rb_node;
@@ -228,7 +229,7 @@ static inline void key_alloc_serial(struct key *key)
         }
 
         /* we've found a suitable hole - arrange for this key to occupy it */
- insert_here:
+insert_here:
         rb_link_node(&key->serial_node, parent, p);
         rb_insert_color(&key->serial_node, &key_serial_tree);
 
@@ -248,7 +249,7 @@ static inline void key_alloc_serial(struct key *key)
  */
 struct key *key_alloc(struct key_type *type, const char *desc,
                       uid_t uid, gid_t gid, struct task_struct *ctx,
-                      key_perm_t perm, int not_in_quota)
+                      key_perm_t perm, unsigned long flags)
 {
         struct key_user *user = NULL;
         struct key *key;
@@ -269,12 +270,14 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 
         /* check that the user's quota permits allocation of another key and
          * its description */
-        if (!not_in_quota) {
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
                 spin_lock(&user->lock);
-                if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
-                    user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
-                    )
-                        goto no_quota;
+                if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
+                        if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
+                            user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
+                            )
+                                goto no_quota;
+                }
 
                 user->qnkeys++;
                 user->qnbytes += quotalen;
@@ -308,7 +311,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
         key->payload.data = NULL;
         key->security = NULL;
 
-        if (!not_in_quota)
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
                 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
 
         memset(&key->type_data, 0, sizeof(key->type_data));
@@ -318,7 +321,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 #endif
 
         /* let the security module know about the key */
-        ret = security_key_alloc(key, ctx);
+        ret = security_key_alloc(key, ctx, flags);
         if (ret < 0)
                 goto security_error;
 
@@ -332,7 +335,7 @@ error:
 security_error:
         kfree(key->description);
         kmem_cache_free(key_jar, key);
-        if (!not_in_quota) {
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
                 spin_lock(&user->lock);
                 user->qnkeys--;
                 user->qnbytes -= quotalen;
@@ -345,7 +348,7 @@ security_error:
 no_memory_3:
         kmem_cache_free(key_jar, key);
 no_memory_2:
-        if (!not_in_quota) {
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
                 spin_lock(&user->lock);
                 user->qnkeys--;
                 user->qnbytes -= quotalen;
@@ -761,7 +764,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
                                const char *description,
                                const void *payload,
                                size_t plen,
-                               int not_in_quota)
+                               unsigned long flags)
 {
         struct key_type *ktype;
         struct key *keyring, *key = NULL;
@@ -822,7 +825,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
 
         /* allocate a new key */
         key = key_alloc(ktype, description, current->fsuid, current->fsgid,
-                        current, perm, not_in_quota);
+                        current, perm, flags);
         if (IS_ERR(key)) {
                 key_ref = ERR_PTR(PTR_ERR(key));
                 goto error_3;
@@ -986,7 +989,7 @@ void unregister_key_type(struct key_type *ktype)
                 if (key->type == ktype) {
                         if (ktype->destroy)
                                 ktype->destroy(key);
-                        memset(&key->payload, 0xbd, sizeof(key->payload));
+                        memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
                 }
         }