[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, 8 insertions, 5 deletions

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 4c670ee..b7a468f 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -624,8 +624,8 @@ long keyctl_keyring_search(key_serial_t ringid,
 
 	/* link the resulting key to the destination keyring if we can */
 	if (dest_ref) {
-		ret = -EACCES;
-		if (!key_permission(key_ref, KEY_LINK))
+		ret = key_permission(key_ref, KEY_LINK);
+		if (ret < 0)
 			goto error6;
 
 		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
@@ -676,8 +676,11 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 	key = key_ref_to_ptr(key_ref);
 
 	/* see if we can read it directly */
-	if (key_permission(key_ref, KEY_READ))
+	ret = key_permission(key_ref, KEY_READ);
+	if (ret == 0)
 		goto can_read_key;
+	if (ret != -EACCES)
+		goto error;
 
 	/* we can't; see if it's searchable from this process's keyrings
 	 * - we automatically take account of the fact that it may be
@@ -726,7 +729,7 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 	if (uid == (uid_t) -1 && gid == (gid_t) -1)
 		goto error;
 
-	key_ref = lookup_user_key(NULL, id, 1, 1, 0);
+	key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 	if (IS_ERR(key_ref)) {
 		ret = PTR_ERR(key_ref);
 		goto error;
@@ -786,7 +789,7 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 		goto error;
 
-	key_ref = lookup_user_key(NULL, id, 1, 1, 0);
+	key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 	if (IS_ERR(key_ref)) {
 		ret = PTR_ERR(key_ref);
 		goto error;