[PATCH] Keys: Split key permissions checking into a .c file
David Howells [Fri, 7 Oct 2005 14:07:38 +0000 (15:07 +0100)]
The attached patch splits key permissions checking out of key-ui.h and
moves it into a .c file.  It's quite large and called quite a lot, and
it's about to get bigger with the addition of LSM support for keys...

key_any_permission() is also discarded as it's no longer used.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/key-ui.h
security/keys/Makefile
security/keys/permission.c [new file with mode: 0644]

index 918c34a..7a2e332 100644 (file)
@@ -38,97 +38,16 @@ struct keyring_list {
        struct key      *keys[0];
 };
 
-
 /*
  * check to see whether permission is granted to use a key in the desired way
  */
-static inline int key_permission(const key_ref_t key_ref, key_perm_t perm)
-{
-       struct key *key = key_ref_to_ptr(key_ref);
-       key_perm_t kperm;
-
-       if (is_key_possessed(key_ref))
-               kperm = key->perm >> 24;
-       else if (key->uid == current->fsuid)
-               kperm = key->perm >> 16;
-       else if (key->gid != -1 &&
-                key->perm & KEY_GRP_ALL &&
-                in_group_p(key->gid)
-                )
-               kperm = key->perm >> 8;
-       else
-               kperm = key->perm;
-
-       kperm = kperm & perm & KEY_ALL;
-
-       return kperm == perm;
-}
-
-/*
- * check to see whether permission is granted to use a key in at least one of
- * the desired ways
- */
-static inline int key_any_permission(const key_ref_t key_ref, key_perm_t perm)
-{
-       struct key *key = key_ref_to_ptr(key_ref);
-       key_perm_t kperm;
-
-       if (is_key_possessed(key_ref))
-               kperm = key->perm >> 24;
-       else if (key->uid == current->fsuid)
-               kperm = key->perm >> 16;
-       else if (key->gid != -1 &&
-                key->perm & KEY_GRP_ALL &&
-                in_group_p(key->gid)
-                )
-               kperm = key->perm >> 8;
-       else
-               kperm = key->perm;
+extern int key_task_permission(const key_ref_t key_ref,
+                              struct task_struct *context,
+                              key_perm_t perm);
 
-       kperm = kperm & perm & KEY_ALL;
-
-       return kperm != 0;
-}
-
-static inline int key_task_groups_search(struct task_struct *tsk, gid_t gid)
-{
-       int ret;
-
-       task_lock(tsk);
-       ret = groups_search(tsk->group_info, gid);
-       task_unlock(tsk);
-       return ret;
-}
-
-static inline int key_task_permission(const key_ref_t key_ref,
-                                     struct task_struct *context,
-                                     key_perm_t perm)
+static inline int key_permission(const key_ref_t key_ref, key_perm_t perm)
 {
-       struct key *key = key_ref_to_ptr(key_ref);
-       key_perm_t kperm;
-
-       if (is_key_possessed(key_ref)) {
-               kperm = key->perm >> 24;
-       }
-       else if (key->uid == context->fsuid) {
-               kperm = key->perm >> 16;
-       }
-       else if (key->gid != -1 &&
-                key->perm & KEY_GRP_ALL && (
-                        key->gid == context->fsgid ||
-                        key_task_groups_search(context, key->gid)
-                        )
-                ) {
-               kperm = key->perm >> 8;
-       }
-       else {
-               kperm = key->perm;
-       }
-
-       kperm = kperm & perm & KEY_ALL;
-
-       return kperm == perm;
-
+       return key_task_permission(key_ref, current, perm);
 }
 
 extern key_ref_t lookup_user_key(struct task_struct *context,
index c392d75..5145adf 100644 (file)
@@ -6,6 +6,7 @@ obj-y := \
        key.o \
        keyring.o \
        keyctl.o \
+       permission.o \
        process_keys.o \
        request_key.o \
        request_key_auth.o \
diff --git a/security/keys/permission.c b/security/keys/permission.c
new file mode 100644 (file)
index 0000000..1c36516
--- /dev/null
@@ -0,0 +1,70 @@
+/* permission.c: key permission determination
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#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
+ */
+int key_task_permission(const key_ref_t key_ref,
+                       struct task_struct *context,
+                       key_perm_t perm)
+{
+       struct key *key;
+       key_perm_t kperm;
+       int ret;
+
+       key = key_ref_to_ptr(key_ref);
+
+       /* use the top 8-bits of permissions for keys the caller possesses */
+       if (is_key_possessed(key_ref)) {
+               kperm = key->perm >> 24;
+               goto use_these_perms;
+       }
+
+       /* use the second 8-bits of permissions for keys the caller owns */
+       if (key->uid == context->fsuid) {
+               kperm = key->perm >> 16;
+               goto use_these_perms;
+       }
+
+       /* 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) {
+                       kperm = key->perm >> 8;
+                       goto use_these_perms;
+               }
+
+               task_lock(context);
+               ret = groups_search(context->group_info, key->gid);
+               task_unlock(context);
+
+               if (ret) {
+                       kperm = key->perm >> 8;
+                       goto use_these_perms;
+               }
+       }
+
+       /* otherwise use the least-significant 8-bits */
+       kperm = key->perm;
+
+use_these_perms:
+       kperm = kperm & perm & KEY_ALL;
+
+       return kperm == perm;
+
+} /* end key_task_permission() */
+
+EXPORT_SYMBOL(key_task_permission);