linux/Documentation/security
David Howells d4f65b5d24 KEYS: Add payload preparsing opportunity prior to key instantiate or update
Give the key type the opportunity to preparse the payload prior to the
instantiation and update routines being called.  This is done with the
provision of two new key type operations:

	int (*preparse)(struct key_preparsed_payload *prep);
	void (*free_preparse)(struct key_preparsed_payload *prep);

If the first operation is present, then it is called before key creation (in
the add/update case) or before the key semaphore is taken (in the update and
instantiate cases).  The second operation is called to clean up if the first
was called.

preparse() is given the opportunity to fill in the following structure:

	struct key_preparsed_payload {
		char		*description;
		void		*type_data[2];
		void		*payload;
		const void	*data;
		size_t		datalen;
		size_t		quotalen;
	};

Before the preparser is called, the first three fields will have been cleared,
the payload pointer and size will be stored in data and datalen and the default
quota size from the key_type struct will be stored into quotalen.

The preparser may parse the payload in any way it likes and may store data in
the type_data[] and payload fields for use by the instantiate() and update()
ops.

The preparser may also propose a description for the key by attaching it as a
string to the description field.  This can be used by passing a NULL or ""
description to the add_key() system call or the key_create_or_update()
function.  This cannot work with request_key() as that required the description
to tell the upcall about the key to be created.

This, for example permits keys that store PGP public keys to generate their own
name from the user ID and public key fingerprint in the key.

The instantiate() and update() operations are then modified to look like this:

	int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
	int (*update)(struct key *key, struct key_preparsed_payload *prep);

and the new payload data is passed in *prep, whether or not it was preparsed.

Signed-off-by: David Howells <dhowells@redhat.com>
2012-09-13 13:06:29 +01:00
..
00-INDEX security: Yama LSM 2012-02-10 09:18:52 +11:00
apparmor.txt Create Documentation/security/, 2011-05-19 15:59:38 -07:00
credentials.txt Documentation: clarify the purpose of LSMs 2011-11-16 12:37:27 +11:00
keys-ecryptfs.txt encrypted-keys: move ecryptfs documentation to proper location 2011-06-30 19:08:14 +10:00
keys-request-key.txt Create Documentation/security/, 2011-05-19 15:59:38 -07:00
keys-trusted-encrypted.txt Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
keys.txt KEYS: Add payload preparsing opportunity prior to key instantiate or update 2012-09-13 13:06:29 +01:00
LSM.txt Documentation: clarify the purpose of LSMs 2011-11-16 12:37:27 +11:00
SELinux.txt Create Documentation/security/, 2011-05-19 15:59:38 -07:00
Smack.txt Smack: allow for significantly longer Smack labels v4 2012-05-14 22:48:38 -07:00
tomoyo.txt Create Documentation/security/, 2011-05-19 15:59:38 -07:00
Yama.txt Yama: higher restrictions should block PTRACE_TRACEME 2012-08-10 19:58:07 +10:00