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3e30148c3d
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
50 lines
2.2 KiB
C
50 lines
2.2 KiB
C
/* keyctl.h: keyctl command IDs
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _LINUX_KEYCTL_H
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#define _LINUX_KEYCTL_H
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/* special process keyring shortcut IDs */
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#define KEY_SPEC_THREAD_KEYRING -1 /* - key ID for thread-specific keyring */
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#define KEY_SPEC_PROCESS_KEYRING -2 /* - key ID for process-specific keyring */
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#define KEY_SPEC_SESSION_KEYRING -3 /* - key ID for session-specific keyring */
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#define KEY_SPEC_USER_KEYRING -4 /* - key ID for UID-specific keyring */
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#define KEY_SPEC_USER_SESSION_KEYRING -5 /* - key ID for UID-session keyring */
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#define KEY_SPEC_GROUP_KEYRING -6 /* - key ID for GID-specific keyring */
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/* request-key default keyrings */
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#define KEY_REQKEY_DEFL_NO_CHANGE -1
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#define KEY_REQKEY_DEFL_DEFAULT 0
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#define KEY_REQKEY_DEFL_THREAD_KEYRING 1
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#define KEY_REQKEY_DEFL_PROCESS_KEYRING 2
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#define KEY_REQKEY_DEFL_SESSION_KEYRING 3
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#define KEY_REQKEY_DEFL_USER_KEYRING 4
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#define KEY_REQKEY_DEFL_USER_SESSION_KEYRING 5
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#define KEY_REQKEY_DEFL_GROUP_KEYRING 6
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/* keyctl commands */
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#define KEYCTL_GET_KEYRING_ID 0 /* ask for a keyring's ID */
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#define KEYCTL_JOIN_SESSION_KEYRING 1 /* join or start named session keyring */
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#define KEYCTL_UPDATE 2 /* update a key */
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#define KEYCTL_REVOKE 3 /* revoke a key */
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#define KEYCTL_CHOWN 4 /* set ownership of a key */
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#define KEYCTL_SETPERM 5 /* set perms on a key */
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#define KEYCTL_DESCRIBE 6 /* describe a key */
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#define KEYCTL_CLEAR 7 /* clear contents of a keyring */
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#define KEYCTL_LINK 8 /* link a key into a keyring */
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#define KEYCTL_UNLINK 9 /* unlink a key from a keyring */
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#define KEYCTL_SEARCH 10 /* search for a key in a keyring */
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#define KEYCTL_READ 11 /* read a key or keyring's contents */
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#define KEYCTL_INSTANTIATE 12 /* instantiate a partially constructed key */
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#define KEYCTL_NEGATE 13 /* negate a partially constructed key */
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#define KEYCTL_SET_REQKEY_KEYRING 14 /* set default request-key keyring */
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#endif /* _LINUX_KEYCTL_H */
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