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authorDavid Howells <dhowells@redhat.com>2008-11-13 18:39:14 -0500
committerJames Morris <jmorris@namei.org>2008-11-13 18:39:14 -0500
commit8bbf4976b59fc9fc2861e79cab7beb3f6d647640 (patch)
tree9bd621217cbdfcf94aca5b220de7363254d7fc23 /include/linux/keyctl.h
parente9e349b051d98799b743ebf248cc2d986fedf090 (diff)
KEYS: Alter use of key instantiation link-to-keyring argument
Alter the use of the key instantiation and negation functions' link-to-keyring arguments. Currently this specifies a keyring in the target process to link the key into, creating the keyring if it doesn't exist. This, however, can be a problem for copy-on-write credentials as it means that the instantiating process can alter the credentials of the requesting process. This patch alters the behaviour such that: (1) If keyctl_instantiate_key() or keyctl_negate_key() are given a specific keyring by ID (ringid >= 0), then that keyring will be used. (2) If keyctl_instantiate_key() or keyctl_negate_key() are given one of the special constants that refer to the requesting process's keyrings (KEY_SPEC_*_KEYRING, all <= 0), then: (a) If sys_request_key() was given a keyring to use (destringid) then the key will be attached to that keyring. (b) If sys_request_key() was given a NULL keyring, then the key being instantiated will be attached to the default keyring as set by keyctl_set_reqkey_keyring(). (3) No extra link will be made. Decision point (1) follows current behaviour, and allows those instantiators who've searched for a specifically named keyring in the requestor's keyring so as to partition the keys by type to still have their named keyrings. Decision point (2) allows the requestor to make sure that the key or keys that get produced by request_key() go where they want, whilst allowing the instantiator to request that the key is retained. This is mainly useful for situations where the instantiator makes a secondary request, the key for which should be retained by the initial requestor: +-----------+ +--------------+ +--------------+ | | | | | | | Requestor |------->| Instantiator |------->| Instantiator | | | | | | | +-----------+ +--------------+ +--------------+ request_key() request_key() This might be useful, for example, in Kerberos, where the requestor requests a ticket, and then the ticket instantiator requests the TGT, which someone else then has to go and fetch. The TGT, however, should be retained in the keyrings of the requestor, not the first instantiator. To make this explict an extra special keyring constant is also added. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'include/linux/keyctl.h')
-rw-r--r--include/linux/keyctl.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
index 656ee6b77a4a..c0688eb72093 100644
--- a/include/linux/keyctl.h
+++ b/include/linux/keyctl.h
@@ -1,6 +1,6 @@
1/* keyctl.h: keyctl command IDs 1/* keyctl.h: keyctl command IDs
2 * 2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. 3 * Copyright (C) 2004, 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com) 4 * Written by David Howells (dhowells@redhat.com)
5 * 5 *
6 * This program is free software; you can redistribute it and/or 6 * This program is free software; you can redistribute it and/or
@@ -20,6 +20,7 @@
20#define KEY_SPEC_USER_SESSION_KEYRING -5 /* - key ID for UID-session keyring */ 20#define KEY_SPEC_USER_SESSION_KEYRING -5 /* - key ID for UID-session keyring */
21#define KEY_SPEC_GROUP_KEYRING -6 /* - key ID for GID-specific keyring */ 21#define KEY_SPEC_GROUP_KEYRING -6 /* - key ID for GID-specific keyring */
22#define KEY_SPEC_REQKEY_AUTH_KEY -7 /* - key ID for assumed request_key auth key */ 22#define KEY_SPEC_REQKEY_AUTH_KEY -7 /* - key ID for assumed request_key auth key */
23#define KEY_SPEC_REQUESTOR_KEYRING -8 /* - key ID for request_key() dest keyring */
23 24
24/* request-key default keyrings */ 25/* request-key default keyrings */
25#define KEY_REQKEY_DEFL_NO_CHANGE -1 26#define KEY_REQKEY_DEFL_NO_CHANGE -1
@@ -30,6 +31,7 @@
30#define KEY_REQKEY_DEFL_USER_KEYRING 4 31#define KEY_REQKEY_DEFL_USER_KEYRING 4
31#define KEY_REQKEY_DEFL_USER_SESSION_KEYRING 5 32#define KEY_REQKEY_DEFL_USER_SESSION_KEYRING 5
32#define KEY_REQKEY_DEFL_GROUP_KEYRING 6 33#define KEY_REQKEY_DEFL_GROUP_KEYRING 6
34#define KEY_REQKEY_DEFL_REQUESTOR_KEYRING 7
33 35
34/* keyctl commands */ 36/* keyctl commands */
35#define KEYCTL_GET_KEYRING_ID 0 /* ask for a keyring's ID */ 37#define KEYCTL_GET_KEYRING_ID 0 /* ask for a keyring's ID */