keys: skip keys from another user namespace

[safe/jmp/linux-2.6] / security / keys / permission.c

diff --git a/security/keys/permission.c b/security/keys/permission.c
index 3b41f9b..0ed802c 100644 (file)
--- a/security/keys/permission.c
+++ b/security/keys/permission.c
@@ -14,12 +14,19 @@
 #include "internal.h"
 
 /*****************************************************************************/
-/*
- * check to see whether permission is granted to use a key in the desired way,
- * but permit the security modules to override
+/**
+ * key_task_permission - Check a key can be used
+ * @key_ref: The key to check
+ * @cred: The credentials to use
+ * @perm: The permissions to check for
+ *
+ * Check to see whether permission is granted to use a key in the desired way,
+ * but permit the security modules to override.
+ *
+ * The caller must hold either a ref on cred or must hold the RCU readlock or a
+ * spinlock.
  */
-int key_task_permission(const key_ref_t key_ref,
-                       struct task_struct *context,
+int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
                        key_perm_t perm)
 {
        struct key *key;
@@ -28,8 +35,11 @@ int key_task_permission(const key_ref_t key_ref,
 
        key = key_ref_to_ptr(key_ref);
 
+       if (key->user->user_ns != cred->user->user_ns)
+               goto use_other_perms;
+
        /* use the second 8-bits of permissions for keys the caller owns */
-       if (key->uid == context->fsuid) {
+       if (key->uid == cred->fsuid) {
                kperm = key->perm >> 16;
                goto use_these_perms;
        }
@@ -37,25 +47,25 @@ int key_task_permission(const key_ref_t key_ref,
        /* use the third 8-bits of permissions for keys the caller has a group
         * membership in common with */
        if (key->gid != -1 && key->perm & KEY_GRP_ALL) {
-               if (key->gid == context->fsgid) {
+               if (key->gid == cred->fsgid) {
                        kperm = key->perm >> 8;
                        goto use_these_perms;
                }
 
-               task_lock(context);
-               ret = groups_search(context->group_info, key->gid);
-               task_unlock(context);
-
+               ret = groups_search(cred->group_info, key->gid);
                if (ret) {
                        kperm = key->perm >> 8;
                        goto use_these_perms;
                }
        }
 
+use_other_perms:
+
        /* otherwise use the least-significant 8-bits */
        kperm = key->perm;
 
 use_these_perms:
+
        /* use the top 8-bits of permissions for keys the caller possesses
         * - possessor permissions are additive with other permissions
         */
@@ -68,7 +78,7 @@ use_these_perms:
                return -EACCES;
 
        /* let LSM be the final arbiter */
-       return security_key_permission(key_ref, context, perm);
+       return security_key_permission(key_ref, cred, perm);
 
 } /* end key_task_permission() */