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/* user_defined.c: user defined key type
*
* Copyright (C) 2004 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/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <asm/uaccess.h>
#include "internal.h"
static int user_instantiate(struct key *key, const void *data, size_t datalen);
static int user_duplicate(struct key *key, const struct key *source);
static int user_update(struct key *key, const void *data, size_t datalen);
static int user_match(const struct key *key, const void *criterion);
static void user_destroy(struct key *key);
static void user_describe(const struct key *user, struct seq_file *m);
static long user_read(const struct key *key,
char __user *buffer, size_t buflen);
/*
* user defined keys take an arbitrary string as the description and an
* arbitrary blob of data as the payload
*/
struct key_type key_type_user = {
.name = "user",
.instantiate = user_instantiate,
.duplicate = user_duplicate,
.update = user_update,
.match = user_match,
.destroy = user_destroy,
.describe = user_describe,
.read = user_read,
};
struct user_key_payload {
struct rcu_head rcu; /* RCU destructor */
unsigned short datalen; /* length of this data */
char data[0]; /* actual data */
};
/*****************************************************************************/
/*
* instantiate a user defined key
*/
static int user_instantiate(struct key *key, const void *data, size_t datalen)
{
struct user_key_payload *upayload;
int ret;
ret = -EINVAL;
if (datalen <= 0 || datalen > 32767 || !data)
goto error;
ret = key_payload_reserve(key, datalen);
if (ret < 0)
goto error;
ret = -ENOMEM;
upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
if (!upayload)
goto error;
/* attach the data */
upayload->datalen = datalen;
memcpy(upayload->data, data, datalen);
rcu_assign_pointer(key->payload.data, upayload);
ret = 0;
error:
return ret;
} /* end user_instantiate() */
/*****************************************************************************/
/*
* duplicate a user defined key
* - both keys' semaphores are locked against further modification
* - the new key cannot yet be accessed
*/
static int user_duplicate(struct key *key, const struct key *source)
{
struct user_key_payload *upayload, *spayload;
int ret;
/* just copy the payload */
ret = -ENOMEM;
upayload = kmalloc(sizeof(*upayload) + source->datalen, GFP_KERNEL);
if (upayload) {
spayload = rcu_dereference(source->payload.data);
BUG_ON(source->datalen != spayload->datalen);
upayload->datalen = key->datalen = spayload->datalen;
memcpy(upayload->data, spayload->data, key->datalen);
key->payload.data = upayload;
ret = 0;
}
return ret;
} /* end user_duplicate() */
/*****************************************************************************/
/*
* dispose of the old data from an updated user defined key
*/
static void user_update_rcu_disposal(struct rcu_head *rcu)
{
struct user_key_payload *upayload;
upayload = container_of(rcu, struct user_key_payload, rcu);
kfree(upayload);
} /* end user_update_rcu_disposal() */
/*****************************************************************************/
/*
* update a user defined key
* - the key's semaphore is write-locked
*/
static int user_update(struct key *key, const void *data, size_t datalen)
{
struct user_key_payload *upayload, *zap;
int ret;
ret = -EINVAL;
if (datalen <= 0 || datalen > 32767 || !data)
goto error;
/* construct a replacement payload */
ret = -ENOMEM;
upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
if (!upayload)
goto error;
upayload->datalen = datalen;
memcpy(upayload->data, data, datalen);
/* check the quota and attach the new data */
zap = upayload;
ret = key_payload_reserve(key, datalen);
if (ret == 0) {
/* attach the new data, displacing the old */
zap = key->payload.data;
rcu_assign_pointer(key->payload.data, upayload);
key->expiry = 0;
}
call_rcu(&zap->rcu, user_update_rcu_disposal);
error:
return ret;
} /* end user_update() */
/*****************************************************************************/
/*
* match users on their name
*/
static int user_match(const struct key *key, const void *description)
{
return strcmp(key->description, description) == 0;
} /* end user_match() */
/*****************************************************************************/
/*
* dispose of the data dangling from the corpse of a user
*/
static void user_destroy(struct key *key)
{
struct user_key_payload *upayload = key->payload.data;
kfree(upayload);
} /* end user_destroy() */
/*****************************************************************************/
/*
* describe the user key
*/
static void user_describe(const struct key *key, struct seq_file *m)
{
seq_puts(m, key->description);
seq_printf(m, ": %u", key->datalen);
} /* end user_describe() */
/*****************************************************************************/
/*
* read the key data
* - the key's semaphore is read-locked
*/
static long user_read(const struct key *key,
char __user *buffer, size_t buflen)
{
struct user_key_payload *upayload;
long ret;
upayload = rcu_dereference(key->payload.data);
ret = upayload->datalen;
/* we can return the data as is */
if (buffer && buflen > 0) {
if (buflen > upayload->datalen)
buflen = upayload->datalen;
if (copy_to_user(buffer, upayload->data, buflen) != 0)
ret = -EFAULT;
}
return ret;
} /* end user_read() */
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