/* 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 <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,	.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 data dangling from the corpse of a user */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);