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/* request_key_auth.c: request key authorisation controlling key def
*
* 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.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <linux/seq_file.h>
#include "internal.h"
static int request_key_auth_instantiate(struct key *, const void *, size_t);
static void request_key_auth_describe(const struct key *, struct seq_file *);
static void request_key_auth_destroy(struct key *);
/*
* 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),
.instantiate = request_key_auth_instantiate,
.describe = request_key_auth_describe,
.destroy = request_key_auth_destroy,
};
/*****************************************************************************/
/*
* instantiate a request-key authorisation record
*/
static int request_key_auth_instantiate(struct key *key,
const void *data,
size_t datalen)
{
struct request_key_auth *rka, *irka;
struct key *instkey;
int ret;
ret = -ENOMEM;
rka = kmalloc(sizeof(*rka), GFP_KERNEL);
if (rka) {
/* see if the calling process is already servicing the key
* request of another process */
instkey = key_get_instantiation_authkey(0);
if (!IS_ERR(instkey)) {
/* it is - use that instantiation context here too */
irka = instkey->payload.data;
rka->context = irka->context;
rka->pid = irka->pid;
key_put(instkey);
}
else {
/* it isn't - use this process as the context */
rka->context = current;
rka->pid = current->pid;
}
rka->target_key = key_get((struct key *) data);
key->payload.data = rka;
ret = 0;
}
return ret;
} /* end request_key_auth_instantiate() */
/*****************************************************************************/
/*
*
*/
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);
seq_printf(m, " pid:%d", rka->pid);
} /* end request_key_auth_describe() */
/*****************************************************************************/
/*
* 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);
key_put(rka->target_key);
} /* end request_key_auth_destroy() */
/*****************************************************************************/
/*
* create a session keyring to be for the invokation of /sbin/request-key and
* stick an authorisation token in it
*/
struct key *request_key_auth_new(struct key *target, struct key **_rkakey)
{
struct key *keyring, *rkakey = NULL;
char desc[20];
int ret;
kenter("%d,", target->serial);
/* allocate a new session keyring */
sprintf(desc, "_req.%u", target->serial);
keyring = keyring_alloc(desc, current->fsuid, current->fsgid, 1, NULL);
if (IS_ERR(keyring)) {
kleave("= %ld", PTR_ERR(keyring));
return keyring;
}
/* allocate the auth key */
sprintf(desc, "%x", target->serial);
rkakey = key_alloc(&key_type_request_key_auth, desc,
current->fsuid, current->fsgid,
KEY_USR_VIEW, 1);
if (IS_ERR(rkakey)) {
key_put(keyring);
kleave("= %ld", PTR_ERR(rkakey));
return rkakey;
}
/* construct and attach to the keyring */
ret = key_instantiate_and_link(rkakey, target, 0, keyring, NULL);
if (ret < 0) {
key_revoke(rkakey);
key_put(rkakey);
key_put(keyring);
kleave("= %d", ret);
return ERR_PTR(ret);
}
*_rkakey = rkakey;
kleave(" = {%d} ({%d})", keyring->serial, rkakey->serial);
return keyring;
} /* end request_key_auth_new() */
/*****************************************************************************/
/*
* get the authorisation key for instantiation of a specific key if attached to
* the current process's keyrings
* - this key is inserted into a keyring and that is set as /sbin/request-key's
* session keyring
* - a target_id of zero specifies any valid token
*/
struct key *key_get_instantiation_authkey(key_serial_t target_id)
{
struct task_struct *tsk = current;
struct key *instkey;
/* we must have our own personal session keyring */
if (!tsk->signal->session_keyring)
return ERR_PTR(-EACCES);
/* and it must contain a suitable request authorisation key
* - lock RCU against session keyring changing
*/
rcu_read_lock();
instkey = keyring_search_instkey(
rcu_dereference(tsk->signal->session_keyring), target_id);
rcu_read_unlock();
return instkey;
} /* end key_get_instantiation_authkey() */
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