root/security/keys/user_defined.c

DEFINITIONS

1. user_instantiate
2. user_update_rcu_disposal
3. user_update
4. user_match
5. user_revoke
6. user_destroy
7. user_describe
8. user_read

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

/*
 * 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,
        .update         = user_update,
        .match          = user_match,
        .revoke         = user_revoke,
        .destroy        = user_destroy,
        .describe       = user_describe,
        .read           = user_read,
};

EXPORT_SYMBOL_GPL(key_type_user);

/*****************************************************************************/
/*
 * instantiate a user defined key
 */
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() */

EXPORT_SYMBOL_GPL(user_instantiate);

/*****************************************************************************/
/*
 * 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
 */
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() */

EXPORT_SYMBOL_GPL(user_update);

/*****************************************************************************/
/*
 * match users on their name
 */
int user_match(const struct key *key, const void *description)
{
        return strcmp(key->description, description) == 0;

} /* end user_match() */

EXPORT_SYMBOL_GPL(user_match);

/*****************************************************************************/
/*
 * 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 = key->payload.data;

        /* clear the quota */
        key_payload_reserve(key, 0);

        if (upayload) {
                rcu_assign_pointer(key->payload.data, NULL);
                call_rcu(&upayload->rcu, user_update_rcu_disposal);
        }

} /* end user_revoke() */

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;

        kfree(upayload);

} /* end user_destroy() */

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);

        seq_printf(m, ": %u", key->datalen);

} /* end user_describe() */

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)
{
        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() */

EXPORT_SYMBOL_GPL(user_read);