[linux-2.6-block.git] / security / keys / request_key_auth.c

/* Request key authorisation token key definition.
 *
 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * See Documentation/security/keys-request-key.txt
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include "internal.h"
#include <keys/user-type.h>

static int request_key_auth_preparse(struct key_preparsed_payload *);
static void request_key_auth_free_preparse(struct key_preparsed_payload *);
static int request_key_auth_instantiate(struct key *,
					struct key_preparsed_payload *);
static void request_key_auth_describe(const struct key *, struct seq_file *);
static void request_key_auth_revoke(struct key *);
static void request_key_auth_destroy(struct key *);
static long request_key_auth_read(const struct key *, char __user *, size_t);

/*
 * The request-key authorisation key type definition.
 */
struct key_type key_type_request_key_auth = {
	.name		= ".request_key_auth",
	.def_datalen	= sizeof(struct request_key_auth),
	.preparse	= request_key_auth_preparse,
	.free_preparse	= request_key_auth_free_preparse,
	.instantiate	= request_key_auth_instantiate,
	.describe	= request_key_auth_describe,
	.revoke		= request_key_auth_revoke,
	.destroy	= request_key_auth_destroy,
	.read		= request_key_auth_read,
};

int request_key_auth_preparse(struct key_preparsed_payload *prep)
{
	return 0;
}

void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
{
}

/*
 * Instantiate a request-key authorisation key.
 */
static int request_key_auth_instantiate(struct key *key,
					struct key_preparsed_payload *prep)
{
	key->payload.data = (struct request_key_auth *)prep->data;
	return 0;
}

/*
 * Describe an authorisation token.
 */
static void request_key_auth_describe(const struct key *key,
				      struct seq_file *m)
{
	struct request_key_auth *rka = key->payload.data;

	seq_puts(m, "key:");
	seq_puts(m, key->description);
	if (key_is_instantiated(key))
		seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
}

/*
 * Read the callout_info data (retrieves the callout information).
 * - the key's semaphore is read-locked
 */
static long request_key_auth_read(const struct key *key,
				  char __user *buffer, size_t buflen)
{
	struct request_key_auth *rka = key->payload.data;
	size_t datalen;
	long ret;

	datalen = rka->callout_len;
	ret = datalen;

	/* we can return the data as is */
	if (buffer && buflen > 0) {
		if (buflen > datalen)
			buflen = datalen;

		if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
			ret = -EFAULT;
	}

	return ret;
}

/*
 * Handle revocation of an authorisation token key.
 *
 * Called with the key sem write-locked.
 */
static void request_key_auth_revoke(struct key *key)
{
	struct request_key_auth *rka = key->payload.data;

	kenter("{%d}", key->serial);

	if (rka->cred) {
		put_cred(rka->cred);
		rka->cred = NULL;
	}
}

/*
 * Destroy an instantiation authorisation token key.
 */
static void request_key_auth_destroy(struct key *key)
{
	struct request_key_auth *rka = key->payload.data;

	kenter("{%d}", key->serial);

	if (rka->cred) {
		put_cred(rka->cred);
		rka->cred = NULL;
	}

	key_put(rka->target_key);
	key_put(rka->dest_keyring);
	kfree(rka->callout_info);
	kfree(rka);
}

/*
 * Create an authorisation token for /sbin/request-key or whoever to gain
 * access to the caller's security data.
 */
struct key *request_key_auth_new(struct key *target, const void *callout_info,
				 size_t callout_len, struct key *dest_keyring)
{
	struct request_key_auth *rka, *irka;
	const struct cred *cred = current->cred;
	struct key *authkey = NULL;
	char desc[20];
	int ret;

	kenter("%d,", target->serial);

	/* allocate a auth record */
	rka = kmalloc(sizeof(*rka), GFP_KERNEL);
	if (!rka) {
		kleave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}
	rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
	if (!rka->callout_info) {
		kleave(" = -ENOMEM");
		kfree(rka);
		return ERR_PTR(-ENOMEM);
	}

	/* see if the calling process is already servicing the key request of
	 * another process */
	if (cred->request_key_auth) {
		/* it is - use that instantiation context here too */
		down_read(&cred->request_key_auth->sem);

		/* if the auth key has been revoked, then the key we're
		 * servicing is already instantiated */
		if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags))
			goto auth_key_revoked;

		irka = cred->request_key_auth->payload.data;
		rka->cred = get_cred(irka->cred);
		rka->pid = irka->pid;

		up_read(&cred->request_key_auth->sem);
	}
	else {
		/* it isn't - use this process as the context */
		rka->cred = get_cred(cred);
		rka->pid = current->pid;
	}

	rka->target_key = key_get(target);
	rka->dest_keyring = key_get(dest_keyring);
	memcpy(rka->callout_info, callout_info, callout_len);
	rka->callout_len = callout_len;

	/* allocate the auth key */
	sprintf(desc, "%x", target->serial);

	authkey = key_alloc(&key_type_request_key_auth, desc,
			    cred->fsuid, cred->fsgid, cred,
			    KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
			    KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
	if (IS_ERR(authkey)) {
		ret = PTR_ERR(authkey);
		goto error_alloc;
	}

	/* construct the auth key */
	ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
	if (ret < 0)
		goto error_inst;

	kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
	return authkey;

auth_key_revoked:
	up_read(&cred->request_key_auth->sem);
	kfree(rka->callout_info);
	kfree(rka);
	kleave("= -EKEYREVOKED");
	return ERR_PTR(-EKEYREVOKED);

error_inst:
	key_revoke(authkey);
	key_put(authkey);
error_alloc:
	key_put(rka->target_key);
	key_put(rka->dest_keyring);
	kfree(rka->callout_info);
	kfree(rka);
	kleave("= %d", ret);
	return ERR_PTR(ret);
}

/*
 * Search the current process's keyrings for the authorisation key for
 * instantiation of a key.
 */
struct key *key_get_instantiation_authkey(key_serial_t target_id)
{
	char description[16];
	struct keyring_search_context ctx = {
		.index_key.type		= &key_type_request_key_auth,
		.index_key.description	= description,
		.cred			= current_cred(),
		.match			= user_match,
		.match_data		= description,
		.flags			= KEYRING_SEARCH_LOOKUP_DIRECT,
	};
	struct key *authkey;
	key_ref_t authkey_ref;

	sprintf(description, "%x", target_id);

	authkey_ref = search_process_keyrings(&ctx);

	if (IS_ERR(authkey_ref)) {
		authkey = ERR_CAST(authkey_ref);
		if (authkey == ERR_PTR(-EAGAIN))
			authkey = ERR_PTR(-ENOKEY);
		goto error;
	}

	authkey = key_ref_to_ptr(authkey_ref);
	if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
		key_put(authkey);
		authkey = ERR_PTR(-EKEYREVOKED);
	}

error:
	return authkey;
}
Commit	Line	Data
	1	/* Request key authorisation token key definition.
	2	*
	3	* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*
	11	* See Documentation/security/keys-request-key.txt
	12	*/
	13
	14	#include <linux/module.h>
	15	#include <linux/sched.h>
	16	#include <linux/err.h>
	17	#include <linux/seq_file.h>
	18	#include <linux/slab.h>
	19	#include <asm/uaccess.h>
	20	#include "internal.h"
	21	#include <keys/user-type.h>
	22
	23	static int request_key_auth_preparse(struct key_preparsed_payload *);
	24	static void request_key_auth_free_preparse(struct key_preparsed_payload *);
	25	static int request_key_auth_instantiate(struct key *,
	26	struct key_preparsed_payload *);
	27	static void request_key_auth_describe(const struct key , struct seq_file );
	28	static void request_key_auth_revoke(struct key *);
	29	static void request_key_auth_destroy(struct key *);
	30	static long request_key_auth_read(const struct key , char __user , size_t);
	31
	32	/*
	33	* The request-key authorisation key type definition.
	34	*/
	35	struct key_type key_type_request_key_auth = {
	36	.name = ".request_key_auth",
	37	.def_datalen = sizeof(struct request_key_auth),
	38	.preparse = request_key_auth_preparse,
	39	.free_preparse = request_key_auth_free_preparse,
	40	.instantiate = request_key_auth_instantiate,
	41	.describe = request_key_auth_describe,
	42	.revoke = request_key_auth_revoke,
	43	.destroy = request_key_auth_destroy,
	44	.read = request_key_auth_read,
	45	};
	46
	47	int request_key_auth_preparse(struct key_preparsed_payload *prep)
	48	{
	49	return 0;
	50	}
	51
	52	void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
	53	{
	54	}
	55
	56	/*
	57	* Instantiate a request-key authorisation key.
	58	*/
	59	static int request_key_auth_instantiate(struct key *key,
	60	struct key_preparsed_payload *prep)
	61	{
	62	key->payload.data = (struct request_key_auth *)prep->data;
	63	return 0;
	64	}
	65
	66	/*
	67	* Describe an authorisation token.
	68	*/
	69	static void request_key_auth_describe(const struct key *key,
	70	struct seq_file *m)
	71	{
	72	struct request_key_auth *rka = key->payload.data;
	73
	74	seq_puts(m, "key:");
	75	seq_puts(m, key->description);
	76	if (key_is_instantiated(key))
	77	seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
	78	}
	79
	80	/*
	81	* Read the callout_info data (retrieves the callout information).
	82	* - the key's semaphore is read-locked
	83	*/
	84	static long request_key_auth_read(const struct key *key,
	85	char __user *buffer, size_t buflen)
	86	{
	87	struct request_key_auth *rka = key->payload.data;
	88	size_t datalen;
	89	long ret;
	90
	91	datalen = rka->callout_len;
	92	ret = datalen;
	93
	94	/* we can return the data as is */
	95	if (buffer && buflen > 0) {
	96	if (buflen > datalen)
	97	buflen = datalen;
	98
	99	if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
	100	ret = -EFAULT;
	101	}
	102
	103	return ret;
	104	}
	105
	106	/*
	107	* Handle revocation of an authorisation token key.
	108	*
	109	* Called with the key sem write-locked.
	110	*/
	111	static void request_key_auth_revoke(struct key *key)
	112	{
	113	struct request_key_auth *rka = key->payload.data;
	114
	115	kenter("{%d}", key->serial);
	116
	117	if (rka->cred) {
	118	put_cred(rka->cred);
	119	rka->cred = NULL;
	120	}
	121	}
	122
	123	/*
	124	* Destroy an instantiation authorisation token key.
	125	*/
	126	static void request_key_auth_destroy(struct key *key)
	127	{
	128	struct request_key_auth *rka = key->payload.data;
	129
	130	kenter("{%d}", key->serial);
	131
	132	if (rka->cred) {
	133	put_cred(rka->cred);
	134	rka->cred = NULL;
	135	}
	136
	137	key_put(rka->target_key);
	138	key_put(rka->dest_keyring);
	139	kfree(rka->callout_info);
	140	kfree(rka);
	141	}
	142
	143	/*
	144	* Create an authorisation token for /sbin/request-key or whoever to gain
	145	* access to the caller's security data.
	146	*/
	147	struct key request_key_auth_new(struct key target, const void *callout_info,
	148	size_t callout_len, struct key *dest_keyring)
	149	{
	150	struct request_key_auth rka, irka;
	151	const struct cred *cred = current->cred;
	152	struct key *authkey = NULL;
	153	char desc[20];
	154	int ret;
	155
	156	kenter("%d,", target->serial);
	157
	158	/* allocate a auth record */
	159	rka = kmalloc(sizeof(*rka), GFP_KERNEL);
	160	if (!rka) {
	161	kleave(" = -ENOMEM");
	162	return ERR_PTR(-ENOMEM);
	163	}
	164	rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
	165	if (!rka->callout_info) {
	166	kleave(" = -ENOMEM");
	167	kfree(rka);
	168	return ERR_PTR(-ENOMEM);
	169	}
	170
	171	/* see if the calling process is already servicing the key request of
	172	* another process */
	173	if (cred->request_key_auth) {
	174	/* it is - use that instantiation context here too */
	175	down_read(&cred->request_key_auth->sem);
	176
	177	/* if the auth key has been revoked, then the key we're
	178	* servicing is already instantiated */
	179	if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags))
	180	goto auth_key_revoked;
	181
	182	irka = cred->request_key_auth->payload.data;
	183	rka->cred = get_cred(irka->cred);
	184	rka->pid = irka->pid;
	185
	186	up_read(&cred->request_key_auth->sem);
	187	}
	188	else {
	189	/* it isn't - use this process as the context */
	190	rka->cred = get_cred(cred);
	191	rka->pid = current->pid;
	192	}
	193
	194	rka->target_key = key_get(target);
	195	rka->dest_keyring = key_get(dest_keyring);
	196	memcpy(rka->callout_info, callout_info, callout_len);
	197	rka->callout_len = callout_len;
	198
	199	/* allocate the auth key */
	200	sprintf(desc, "%x", target->serial);
	201
	202	authkey = key_alloc(&key_type_request_key_auth, desc,
	203	cred->fsuid, cred->fsgid, cred,
	204	KEY_POS_VIEW \| KEY_POS_READ \| KEY_POS_SEARCH \|
	205	KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
	206	if (IS_ERR(authkey)) {
	207	ret = PTR_ERR(authkey);
	208	goto error_alloc;
	209	}
	210
	211	/* construct the auth key */
	212	ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
	213	if (ret < 0)
	214	goto error_inst;
	215
	216	kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
	217	return authkey;
	218
	219	auth_key_revoked:
	220	up_read(&cred->request_key_auth->sem);
	221	kfree(rka->callout_info);
	222	kfree(rka);
	223	kleave("= -EKEYREVOKED");
	224	return ERR_PTR(-EKEYREVOKED);
	225
	226	error_inst:
	227	key_revoke(authkey);
	228	key_put(authkey);
	229	error_alloc:
	230	key_put(rka->target_key);
	231	key_put(rka->dest_keyring);
	232	kfree(rka->callout_info);
	233	kfree(rka);
	234	kleave("= %d", ret);
	235	return ERR_PTR(ret);
	236	}
	237
	238	/*
	239	* Search the current process's keyrings for the authorisation key for
	240	* instantiation of a key.
	241	*/
	242	struct key *key_get_instantiation_authkey(key_serial_t target_id)
	243	{
	244	char description[16];
	245	struct keyring_search_context ctx = {
	246	.index_key.type = &key_type_request_key_auth,
	247	.index_key.description = description,
	248	.cred = current_cred(),
	249	.match = user_match,
	250	.match_data = description,
	251	.flags = KEYRING_SEARCH_LOOKUP_DIRECT,
	252	};
	253	struct key *authkey;
	254	key_ref_t authkey_ref;
	255
	256	sprintf(description, "%x", target_id);
	257
	258	authkey_ref = search_process_keyrings(&ctx);
	259
	260	if (IS_ERR(authkey_ref)) {
	261	authkey = ERR_CAST(authkey_ref);
	262	if (authkey == ERR_PTR(-EAGAIN))
	263	authkey = ERR_PTR(-ENOKEY);
	264	goto error;
	265	}
	266
	267	authkey = key_ref_to_ptr(authkey_ref);
	268	if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
	269	key_put(authkey);
	270	authkey = ERR_PTR(-EKEYREVOKED);
	271	}
	272
	273	error:
	274	return authkey;
	275	}