[PATCH] Keys: Add LSM hooks for key management [try #3]

The attached patch adds LSM hooks for key management facilities. The notable
changes are:

 (1) The key struct now supports a security pointer for the use of security
     modules. This will permit key labelling and restrictions on which
     programs may access a key.

 (2) Security modules get a chance to note (or abort) the allocation of a key.

 (3) The key permission checking can now be enhanced by the security modules;
     the permissions check consults LSM if all other checks bear out.

 (4) The key permissions checking functions now return an error code rather
     than a boolean value.

 (5) An extra permission has been added to govern the modification of
     attributes (UID, GID, permissions).

Note that there isn't an LSM hook specifically for each keyctl() operation,
but rather the permissions hook allows control of individual operations based
on the permission request bits.

Key management access control through LSM is enabled by automatically if both
CONFIG_KEYS and CONFIG_SECURITY are enabled.

This should be applied on top of the patch ensubjected:

	[PATCH] Keys: Possessor permissions should be additive

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index d42d2158ce13..566b1cc0118a 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -39,7 +39,7 @@ struct key root_user_keyring = {
         .type           = &key_type_keyring,
         .user           = &root_key_user,
         .sem            = __RWSEM_INITIALIZER(root_user_keyring.sem),
-        .perm           = KEY_POS_ALL | KEY_USR_ALL,
+        .perm           = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
         .flags          = 1 << KEY_FLAG_INSTANTIATED,
         .description    = "_uid.0",
 #ifdef KEY_DEBUGGING
@@ -54,7 +54,7 @@ struct key root_session_keyring = {
         .type           = &key_type_keyring,
         .user           = &root_key_user,
         .sem            = __RWSEM_INITIALIZER(root_session_keyring.sem),
-        .perm           = KEY_POS_ALL | KEY_USR_ALL,
+        .perm           = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
         .flags          = 1 << KEY_FLAG_INSTANTIATED,
         .description    = "_uid_ses.0",
 #ifdef KEY_DEBUGGING
@@ -666,9 +666,8 @@ key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
                 goto invalid_key;
 
         /* check the permissions */
-        ret = -EACCES;
-
-        if (!key_task_permission(key_ref, context, perm))
+        ret = key_task_permission(key_ref, context, perm);
+        if (ret < 0)
                 goto invalid_key;
 
 error: