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// SPDX-License-Identifier: GPL-2.0-or-later
/* user_defined.c: user defined key type
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/export.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <keys/user-type.h>
#include <linux/uaccess.h>
#include "internal.h"
static int logon_vet_description(const char *desc);
/*
* 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",
.preparse = user_preparse,
.free_preparse = user_free_preparse,
.instantiate = generic_key_instantiate,
.update = user_update,
.revoke = user_revoke,
.destroy = user_destroy,
.describe = user_describe,
.read = user_read,
};
EXPORT_SYMBOL_GPL(key_type_user);
/*
* This key type is essentially the same as key_type_user, but it does
* not define a .read op. This is suitable for storing username and
* password pairs in the keyring that you do not want to be readable
* from userspace.
*/
struct key_type key_type_logon = {
.name = "logon",
.preparse = user_preparse,
.free_preparse = user_free_preparse,
.instantiate = generic_key_instantiate,
.update = user_update,
.revoke = user_revoke,
.destroy = user_destroy,
.describe = user_describe,
.vet_description = logon_vet_description,
};
EXPORT_SYMBOL_GPL(key_type_logon);
/*
* Preparse a user defined key payload
*/
int user_preparse(struct key_preparsed_payload *prep)
{
struct user_key_payload *upayload;
size_t datalen = prep->datalen;
if (datalen <= 0 || datalen > 32767 || !prep->data)
return -EINVAL;
upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
if (!upayload)
return -ENOMEM;
/* attach the data */
prep->quotalen = datalen;
prep->payload.data[0] = upayload;
upayload->datalen = datalen;
memcpy(upayload->data, prep->data, datalen);
return 0;
}
EXPORT_SYMBOL_GPL(user_preparse);
/*
* Free a preparse of a user defined key payload
*/
void user_free_preparse(struct key_preparsed_payload *prep)
{
kzfree(prep->payload.data[0]);
}
EXPORT_SYMBOL_GPL(user_free_preparse);
static void user_free_payload_rcu(struct rcu_head *head)
{
struct user_key_payload *payload;
payload = container_of(head, struct user_key_payload, rcu);
kzfree(payload);
}
/*
* update a user defined key
* - the key's semaphore is write-locked
*/
int user_update(struct key *key, struct key_preparsed_payload *prep)
{
struct user_key_payload *zap = NULL;
int ret;
/* check the quota and attach the new data */
ret = key_payload_reserve(key, prep->datalen);
if (ret < 0)
return ret;
/* attach the new data, displacing the old */
key->expiry = prep->expiry;
if (key_is_positive(key))
zap = dereference_key_locked(key);
rcu_assign_keypointer(key, prep->payload.data[0]);
prep->payload.data[0] = NULL;
if (zap)
call_rcu(&zap->rcu, user_free_payload_rcu);
return ret;
}
EXPORT_SYMBOL_GPL(user_update);
/*
* dispose of the links from a revoked keyring
* - called with the key sem write-locked
*/
void user_revoke(struct key *key)
{
struct user_key_payload *upayload = user_key_payload_locked(key);
/* clear the quota */
key_payload_reserve(key, 0);
if (upayload) {
rcu_assign_keypointer(key, NULL);
call_rcu(&upayload->rcu, user_free_payload_rcu);
}
}
EXPORT_SYMBOL(user_revoke);
/*
* dispose of the data dangling from the corpse of a user key
*/
void user_destroy(struct key *key)
{
struct user_key_payload *upayload = key->payload.data[0];
kzfree(upayload);
}
EXPORT_SYMBOL_GPL(user_destroy);
/*
* describe the user key
*/
void user_describe(const struct key *key, struct seq_file *m)
{
seq_puts(m, key->description);
if (key_is_positive(key))
seq_printf(m, ": %u", key->datalen);
}
EXPORT_SYMBOL_GPL(user_describe);
/*
* read the key data
* - the key's semaphore is read-locked
*/
long user_read(const struct key *key, char __user *buffer, size_t buflen)
{
const struct user_key_payload *upayload;
long ret;
upayload = user_key_payload_locked(key);
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;
}
EXPORT_SYMBOL_GPL(user_read);
/* Vet the description for a "logon" key */
static int logon_vet_description(const char *desc)
{
char *p;
/* require a "qualified" description string */
p = strchr(desc, ':');
if (!p)
return -EINVAL;
/* also reject description with ':' as first char */
if (p == desc)
return -EINVAL;
return 0;
}
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