/* 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.
*
* See Documentation/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"
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_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),
.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,
};
/*****************************************************************************/
/*
* instantiate a request-key authorisation key
*/
static int request_key_auth_instantiate(struct key *key,
const void *data,
size_t datalen)
{
key->payload.data = (struct request_key_auth *) data;
return 0;
} /* end request_key_auth_instantiate() */
/*****************************************************************************/
/*
* reading a request-key authorisation key retrieves the callout information
*/
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 ci:%zu", rka->pid, rka->callout_len);
} /* end request_key_auth_describe() */
/*****************************************************************************/
/*
* read the callout_info data
* - 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;
} /* end request_key_auth_read() */
/*****************************************************************************/
/*
* 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->context) {
put_task_struct(rka->context);
rka->context = NULL;
}
} /* end request_key_auth_revoke() */
/*****************************************************************************/
/*
* 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->context) {
put_task_struct(rka->context);
rka->context = NULL;
}
key_put(rka->target_key);
kfree(rka->callout_info);
kfree(rka);
} /* end request_key_auth_destroy() */
/*****************************************************************************/
/*
* 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 request_key_auth *rka, *irka;
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 (current->request_key_auth) {
/* it is - use that instantiation context here too */
down_read(¤t->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,
¤t->request_key_auth->flags))
goto auth_key_revoked;
irka = current->request_key_auth->payload.data;
rka->context = irka->context;
rka->pid = irka->pid;
get_task_struct(rka->context);
up_read(¤t->request_key_auth->sem);
}
else {
/* it isn't - use this process as the context */
rka->context = current;
rka->pid = current->pid;
get_task_struct(rka->context);
}
rka->target_key = key_get(target);
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,
current->fsuid, current->fsgid, current,
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 and attach to the keyring */
ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
if (ret < 0)
goto error_inst;
kleave(" = {%d}", authkey->serial);
return authkey;
auth_key_revoked:
up_read(¤t->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);
kfree(rka->callout_info);
kfree(rka);
kleave("= %d", ret);
return ERR_PTR(ret);
} /* end request_key_auth_new() */
/*****************************************************************************/
/*
* see if an authorisation key is associated with a particular key
*/
static int key_get_instantiation_authkey_match(const struct key *key,
const void *_id)
{
struct request_key_auth *rka = key->payload.data;
key_serial_t id = (key_serial_t)(unsigned long) _id;
return rka->target_key->serial == id;
} /* end key_get_instantiation_authkey_match() */
/*****************************************************************************/
/*
* 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 key *authkey;
key_ref_t authkey_ref;
authkey_ref = search_process_keyrings(
&key_type_request_key_auth,
(void *) (unsigned long) target_id,
key_get_instantiation_authkey_match,
current);
if (IS_ERR(authkey_ref)) {
authkey = ERR_CAST(authkey_ref);
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;
} /* end key_get_instantiation_authkey() */
