197 lines
4.5 KiB
C
197 lines
4.5 KiB
C
/* user_defined.c: user defined key type
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#include <linux/err.h>
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#include <keys/user-type.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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/*
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* user defined keys take an arbitrary string as the description and an
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* arbitrary blob of data as the payload
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*/
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struct key_type key_type_user = {
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.name = "user",
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.instantiate = user_instantiate,
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.update = user_update,
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.match = user_match,
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.destroy = user_destroy,
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.describe = user_describe,
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.read = user_read,
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};
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EXPORT_SYMBOL_GPL(key_type_user);
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/*****************************************************************************/
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/*
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* instantiate a user defined key
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*/
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int user_instantiate(struct key *key, const void *data, size_t datalen)
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{
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struct user_key_payload *upayload;
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int ret;
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ret = -EINVAL;
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if (datalen <= 0 || datalen > 32767 || !data)
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goto error;
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ret = key_payload_reserve(key, datalen);
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if (ret < 0)
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goto error;
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ret = -ENOMEM;
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upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
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if (!upayload)
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goto error;
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/* attach the data */
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upayload->datalen = datalen;
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memcpy(upayload->data, data, datalen);
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rcu_assign_pointer(key->payload.data, upayload);
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ret = 0;
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error:
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return ret;
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} /* end user_instantiate() */
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EXPORT_SYMBOL_GPL(user_instantiate);
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/*****************************************************************************/
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/*
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* dispose of the old data from an updated user defined key
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*/
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static void user_update_rcu_disposal(struct rcu_head *rcu)
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{
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struct user_key_payload *upayload;
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upayload = container_of(rcu, struct user_key_payload, rcu);
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kfree(upayload);
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} /* end user_update_rcu_disposal() */
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/*****************************************************************************/
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/*
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* update a user defined key
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* - the key's semaphore is write-locked
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*/
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int user_update(struct key *key, const void *data, size_t datalen)
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{
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struct user_key_payload *upayload, *zap;
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int ret;
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ret = -EINVAL;
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if (datalen <= 0 || datalen > 32767 || !data)
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goto error;
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/* construct a replacement payload */
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ret = -ENOMEM;
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upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
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if (!upayload)
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goto error;
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upayload->datalen = datalen;
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memcpy(upayload->data, data, datalen);
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/* check the quota and attach the new data */
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zap = upayload;
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ret = key_payload_reserve(key, datalen);
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if (ret == 0) {
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/* attach the new data, displacing the old */
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zap = key->payload.data;
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rcu_assign_pointer(key->payload.data, upayload);
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key->expiry = 0;
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}
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call_rcu(&zap->rcu, user_update_rcu_disposal);
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error:
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return ret;
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} /* end user_update() */
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EXPORT_SYMBOL_GPL(user_update);
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/*****************************************************************************/
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/*
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* match users on their name
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*/
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int user_match(const struct key *key, const void *description)
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{
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return strcmp(key->description, description) == 0;
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} /* end user_match() */
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EXPORT_SYMBOL_GPL(user_match);
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/*****************************************************************************/
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/*
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* dispose of the data dangling from the corpse of a user
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*/
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void user_destroy(struct key *key)
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{
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struct user_key_payload *upayload = key->payload.data;
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kfree(upayload);
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} /* end user_destroy() */
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EXPORT_SYMBOL_GPL(user_destroy);
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/*****************************************************************************/
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/*
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* describe the user key
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*/
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void user_describe(const struct key *key, struct seq_file *m)
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{
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seq_puts(m, key->description);
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seq_printf(m, ": %u", key->datalen);
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} /* end user_describe() */
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EXPORT_SYMBOL_GPL(user_describe);
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/*****************************************************************************/
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/*
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* read the key data
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* - the key's semaphore is read-locked
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*/
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long user_read(const struct key *key, char __user *buffer, size_t buflen)
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{
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struct user_key_payload *upayload;
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long ret;
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upayload = rcu_dereference(key->payload.data);
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ret = upayload->datalen;
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/* we can return the data as is */
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if (buffer && buflen > 0) {
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if (buflen > upayload->datalen)
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buflen = upayload->datalen;
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if (copy_to_user(buffer, upayload->data, buflen) != 0)
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ret = -EFAULT;
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}
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return ret;
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} /* end user_read() */
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EXPORT_SYMBOL_GPL(user_read);
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