[linux-2.6-block.git] / fs / ecryptfs / miscdev.c

/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2008 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <linux/fs.h>
#include <linux/hash.h>
#include <linux/random.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/module.h>
#include "ecryptfs_kernel.h"

static atomic_t ecryptfs_num_miscdev_opens;

/**
 * ecryptfs_miscdev_poll
 * @file: dev file
 * @pt: dev poll table (ignored)
 *
 * Returns the poll mask
 */
static __poll_t
ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
{
	struct ecryptfs_daemon *daemon = file->private_data;
	__poll_t mask = 0;

	mutex_lock(&daemon->mux);
	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
		printk(KERN_WARNING "%s: Attempt to poll on zombified "
		       "daemon\n", __func__);
		goto out_unlock_daemon;
	}
	if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
		goto out_unlock_daemon;
	if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
		goto out_unlock_daemon;
	daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
	mutex_unlock(&daemon->mux);
	poll_wait(file, &daemon->wait, pt);
	mutex_lock(&daemon->mux);
	if (!list_empty(&daemon->msg_ctx_out_queue))
		mask |= POLLIN | POLLRDNORM;
out_unlock_daemon:
	daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
	mutex_unlock(&daemon->mux);
	return mask;
}

/**
 * ecryptfs_miscdev_open
 * @inode: inode of miscdev handle (ignored)
 * @file: file for miscdev handle
 *
 * Returns zero on success; non-zero otherwise
 */
static int
ecryptfs_miscdev_open(struct inode *inode, struct file *file)
{
	struct ecryptfs_daemon *daemon = NULL;
	int rc;

	mutex_lock(&ecryptfs_daemon_hash_mux);
	rc = ecryptfs_find_daemon_by_euid(&daemon);
	if (!rc) {
		rc = -EINVAL;
		goto out_unlock_daemon_list;
	}
	rc = ecryptfs_spawn_daemon(&daemon, file);
	if (rc) {
		printk(KERN_ERR "%s: Error attempting to spawn daemon; "
		       "rc = [%d]\n", __func__, rc);
		goto out_unlock_daemon_list;
	}
	mutex_lock(&daemon->mux);
	if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
		rc = -EBUSY;
		goto out_unlock_daemon;
	}
	daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN;
	file->private_data = daemon;
	atomic_inc(&ecryptfs_num_miscdev_opens);
out_unlock_daemon:
	mutex_unlock(&daemon->mux);
out_unlock_daemon_list:
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	return rc;
}

/**
 * ecryptfs_miscdev_release
 * @inode: inode of fs/ecryptfs/euid handle (ignored)
 * @file: file for fs/ecryptfs/euid handle
 *
 * This keeps the daemon registered until the daemon sends another
 * ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
 *
 * Returns zero on success; non-zero otherwise
 */
static int
ecryptfs_miscdev_release(struct inode *inode, struct file *file)
{
	struct ecryptfs_daemon *daemon = file->private_data;
	int rc;

	mutex_lock(&daemon->mux);
	BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
	daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
	atomic_dec(&ecryptfs_num_miscdev_opens);
	mutex_unlock(&daemon->mux);

	mutex_lock(&ecryptfs_daemon_hash_mux);
	rc = ecryptfs_exorcise_daemon(daemon);
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	if (rc) {
		printk(KERN_CRIT "%s: Fatal error whilst attempting to "
		       "shut down daemon; rc = [%d]. Please report this "
		       "bug.\n", __func__, rc);
		BUG();
	}
	return rc;
}

/**
 * ecryptfs_send_miscdev
 * @data: Data to send to daemon; may be NULL
 * @data_size: Amount of data to send to daemon
 * @msg_ctx: Message context, which is used to handle the reply. If
 *           this is NULL, then we do not expect a reply.
 * @msg_type: Type of message
 * @msg_flags: Flags for message
 * @daemon: eCryptfs daemon object
 *
 * Add msg_ctx to queue and then, if it exists, notify the blocked
 * miscdevess about the data being available. Must be called with
 * ecryptfs_daemon_hash_mux held.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_send_miscdev(char *data, size_t data_size,
			  struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
			  u16 msg_flags, struct ecryptfs_daemon *daemon)
{
	struct ecryptfs_message *msg;

	msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
	if (!msg)
		return -ENOMEM;

	mutex_lock(&msg_ctx->mux);
	msg_ctx->msg = msg;
	msg_ctx->msg->index = msg_ctx->index;
	msg_ctx->msg->data_len = data_size;
	msg_ctx->type = msg_type;
	memcpy(msg_ctx->msg->data, data, data_size);
	msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
	list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
	mutex_unlock(&msg_ctx->mux);

	mutex_lock(&daemon->mux);
	daemon->num_queued_msg_ctx++;
	wake_up_interruptible(&daemon->wait);
	mutex_unlock(&daemon->mux);

	return 0;
}

/*
 * miscdevfs packet format:
 *  Octet 0: Type
 *  Octets 1-4: network byte order msg_ctx->counter
 *  Octets 5-N0: Size of struct ecryptfs_message to follow
 *  Octets N0-N1: struct ecryptfs_message (including data)
 *
 *  Octets 5-N1 not written if the packet type does not include a message
 */
#define PKT_TYPE_SIZE		1
#define PKT_CTR_SIZE		4
#define MIN_NON_MSG_PKT_SIZE	(PKT_TYPE_SIZE + PKT_CTR_SIZE)
#define MIN_MSG_PKT_SIZE	(PKT_TYPE_SIZE + PKT_CTR_SIZE \
				 + ECRYPTFS_MIN_PKT_LEN_SIZE)
/* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
#define MAX_MSG_PKT_SIZE	(PKT_TYPE_SIZE + PKT_CTR_SIZE \
				 + ECRYPTFS_MAX_PKT_LEN_SIZE \
				 + sizeof(struct ecryptfs_message) \
				 + 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
#define PKT_TYPE_OFFSET		0
#define PKT_CTR_OFFSET		PKT_TYPE_SIZE
#define PKT_LEN_OFFSET		(PKT_TYPE_SIZE + PKT_CTR_SIZE)

/**
 * ecryptfs_miscdev_read - format and send message from queue
 * @file: miscdevfs handle
 * @buf: User buffer into which to copy the next message on the daemon queue
 * @count: Amount of space available in @buf
 * @ppos: Offset in file (ignored)
 *
 * Pulls the most recent message from the daemon queue, formats it for
 * being sent via a miscdevfs handle, and copies it into @buf
 *
 * Returns the number of bytes copied into the user buffer
 */
static ssize_t
ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
		      loff_t *ppos)
{
	struct ecryptfs_daemon *daemon = file->private_data;
	struct ecryptfs_msg_ctx *msg_ctx;
	size_t packet_length_size;
	char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
	size_t i;
	size_t total_length;
	int rc;

	mutex_lock(&daemon->mux);
	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
		rc = 0;
		printk(KERN_WARNING "%s: Attempt to read from zombified "
		       "daemon\n", __func__);
		goto out_unlock_daemon;
	}
	if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
		rc = 0;
		goto out_unlock_daemon;
	}
	/* This daemon will not go away so long as this flag is set */
	daemon->flags |= ECRYPTFS_DAEMON_IN_READ;
check_list:
	if (list_empty(&daemon->msg_ctx_out_queue)) {
		mutex_unlock(&daemon->mux);
		rc = wait_event_interruptible(
			daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
		mutex_lock(&daemon->mux);
		if (rc < 0) {
			rc = 0;
			goto out_unlock_daemon;
		}
	}
	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
		rc = 0;
		goto out_unlock_daemon;
	}
	if (list_empty(&daemon->msg_ctx_out_queue)) {
		/* Something else jumped in since the
		 * wait_event_interruptable() and removed the
		 * message from the queue; try again */
		goto check_list;
	}
	msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
				   struct ecryptfs_msg_ctx, daemon_out_list);
	BUG_ON(!msg_ctx);
	mutex_lock(&msg_ctx->mux);
	if (msg_ctx->msg) {
		rc = ecryptfs_write_packet_length(packet_length,
						  msg_ctx->msg_size,
						  &packet_length_size);
		if (rc) {
			rc = 0;
			printk(KERN_WARNING "%s: Error writing packet length; "
			       "rc = [%d]\n", __func__, rc);
			goto out_unlock_msg_ctx;
		}
	} else {
		packet_length_size = 0;
		msg_ctx->msg_size = 0;
	}
	total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
			+ msg_ctx->msg_size);
	if (count < total_length) {
		rc = 0;
		printk(KERN_WARNING "%s: Only given user buffer of "
		       "size [%zd], but we need [%zd] to read the "
		       "pending message\n", __func__, count, total_length);
		goto out_unlock_msg_ctx;
	}
	rc = -EFAULT;
	if (put_user(msg_ctx->type, buf))
		goto out_unlock_msg_ctx;
	if (put_user(cpu_to_be32(msg_ctx->counter),
		     (__be32 __user *)(&buf[PKT_CTR_OFFSET])))
		goto out_unlock_msg_ctx;
	i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
	if (msg_ctx->msg) {
		if (copy_to_user(&buf[i], packet_length, packet_length_size))
			goto out_unlock_msg_ctx;
		i += packet_length_size;
		if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
			goto out_unlock_msg_ctx;
		i += msg_ctx->msg_size;
	}
	rc = i;
	list_del(&msg_ctx->daemon_out_list);
	kfree(msg_ctx->msg);
	msg_ctx->msg = NULL;
	/* We do not expect a reply from the userspace daemon for any
	 * message type other than ECRYPTFS_MSG_REQUEST */
	if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
		ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
out_unlock_msg_ctx:
	mutex_unlock(&msg_ctx->mux);
out_unlock_daemon:
	daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
	mutex_unlock(&daemon->mux);
	return rc;
}

/**
 * ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
 * @data: Bytes comprising struct ecryptfs_message
 * @data_size: sizeof(struct ecryptfs_message) + data len
 * @seq: Sequence number for miscdev response packet
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_miscdev_response(struct ecryptfs_daemon *daemon, char *data,
				     size_t data_size, u32 seq)
{
	struct ecryptfs_message *msg = (struct ecryptfs_message *)data;
	int rc;

	if ((sizeof(*msg) + msg->data_len) != data_size) {
		printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
		       "[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
		       (sizeof(*msg) + msg->data_len), data_size);
		rc = -EINVAL;
		goto out;
	}
	rc = ecryptfs_process_response(daemon, msg, seq);
	if (rc)
		printk(KERN_ERR
		       "Error processing response message; rc = [%d]\n", rc);
out:
	return rc;
}

/**
 * ecryptfs_miscdev_write - handle write to daemon miscdev handle
 * @file: File for misc dev handle
 * @buf: Buffer containing user data
 * @count: Amount of data in @buf
 * @ppos: Pointer to offset in file (ignored)
 *
 * Returns the number of bytes read from @buf
 */
static ssize_t
ecryptfs_miscdev_write(struct file *file, const char __user *buf,
		       size_t count, loff_t *ppos)
{
	__be32 counter_nbo;
	u32 seq;
	size_t packet_size, packet_size_length;
	char *data;
	unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
	ssize_t rc;

	if (count == 0) {
		return 0;
	} else if (count == MIN_NON_MSG_PKT_SIZE) {
		/* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
		goto memdup;
	} else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
		printk(KERN_WARNING "%s: Acceptable packet size range is "
		       "[%d-%zu], but amount of data written is [%zu].\n",
		       __func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
		return -EINVAL;
	}

	if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
			   sizeof(packet_size_peek))) {
		printk(KERN_WARNING "%s: Error while inspecting packet size\n",
		       __func__);
		return -EFAULT;
	}

	rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
					  &packet_size_length);
	if (rc) {
		printk(KERN_WARNING "%s: Error parsing packet length; "
		       "rc = [%zd]\n", __func__, rc);
		return rc;
	}

	if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
	    != count) {
		printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
		       packet_size);
		return -EINVAL;
	}

memdup:
	data = memdup_user(buf, count);
	if (IS_ERR(data)) {
		printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
		       __func__, PTR_ERR(data));
		return PTR_ERR(data);
	}
	switch (data[PKT_TYPE_OFFSET]) {
	case ECRYPTFS_MSG_RESPONSE:
		if (count < (MIN_MSG_PKT_SIZE
			     + sizeof(struct ecryptfs_message))) {
			printk(KERN_WARNING "%s: Minimum acceptable packet "
			       "size is [%zd], but amount of data written is "
			       "only [%zd]. Discarding response packet.\n",
			       __func__,
			       (MIN_MSG_PKT_SIZE
				+ sizeof(struct ecryptfs_message)), count);
			rc = -EINVAL;
			goto out_free;
		}
		memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
		seq = be32_to_cpu(counter_nbo);
		rc = ecryptfs_miscdev_response(file->private_data,
				&data[PKT_LEN_OFFSET + packet_size_length],
				packet_size, seq);
		if (rc) {
			printk(KERN_WARNING "%s: Failed to deliver miscdev "
			       "response to requesting operation; rc = [%zd]\n",
			       __func__, rc);
			goto out_free;
		}
		break;
	case ECRYPTFS_MSG_HELO:
	case ECRYPTFS_MSG_QUIT:
		break;
	default:
		ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
				"message of unrecognized type [%d]\n",
				data[0]);
		rc = -EINVAL;
		goto out_free;
	}
	rc = count;
out_free:
	kfree(data);
	return rc;
}


static const struct file_operations ecryptfs_miscdev_fops = {
	.owner   = THIS_MODULE,
	.open    = ecryptfs_miscdev_open,
	.poll    = ecryptfs_miscdev_poll,
	.read    = ecryptfs_miscdev_read,
	.write   = ecryptfs_miscdev_write,
	.release = ecryptfs_miscdev_release,
	.llseek  = noop_llseek,
};

static struct miscdevice ecryptfs_miscdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name  = "ecryptfs",
	.fops  = &ecryptfs_miscdev_fops
};

/**
 * ecryptfs_init_ecryptfs_miscdev
 *
 * Messages sent to the userspace daemon from the kernel are placed on
 * a queue associated with the daemon. The next read against the
 * miscdev handle by that daemon will return the oldest message placed
 * on the message queue for the daemon.
 *
 * Returns zero on success; non-zero otherwise
 */
int __init ecryptfs_init_ecryptfs_miscdev(void)
{
	int rc;

	atomic_set(&ecryptfs_num_miscdev_opens, 0);
	rc = misc_register(&ecryptfs_miscdev);
	if (rc)
		printk(KERN_ERR "%s: Failed to register miscellaneous device "
		       "for communications with userspace daemons; rc = [%d]\n",
		       __func__, rc);
	return rc;
}

/**
 * ecryptfs_destroy_ecryptfs_miscdev
 *
 * All of the daemons must be exorcised prior to calling this
 * function.
 */
void ecryptfs_destroy_ecryptfs_miscdev(void)
{
	BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0);
	misc_deregister(&ecryptfs_miscdev);
}
Commit	Line	Data
8bf2debd MH	1	/**
	2	* eCryptfs: Linux filesystem encryption layer
	3	*
	4	* Copyright (C) 2008 International Business Machines Corp.
	5	* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License version
	9	* 2 as published by the Free Software Foundation.
	10	*
	11	* This program is distributed in the hope that it will be useful, but
	12	* WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	19	* 02111-1307, USA.
	20	*/
	21
	22	#include <linux/fs.h>
	23	#include <linux/hash.h>
	24	#include <linux/random.h>
	25	#include <linux/miscdevice.h>
	26	#include <linux/poll.h>
5a0e3ad6	27	#include <linux/slab.h>
8bf2debd MH	28	#include <linux/wait.h>
	29	#include <linux/module.h>
	30	#include "ecryptfs_kernel.h"
	31
	32	static atomic_t ecryptfs_num_miscdev_opens;
	33
	34	/**
	35	* ecryptfs_miscdev_poll
2ecaf55d	36	* @file: dev file
8bf2debd MH	37	* @pt: dev poll table (ignored)
	38	*
	39	* Returns the poll mask
	40	*/
076ccb76	41	static __poll_t
8bf2debd MH	42	ecryptfs_miscdev_poll(struct file file, poll_table pt)
8bf2debd MH	43	{
2ecaf55d	44	struct ecryptfs_daemon *daemon = file->private_data;
076ccb76	45	__poll_t mask = 0;
8bf2debd	46
8bf2debd	47	mutex_lock(&daemon->mux);
8bf2debd MH	48	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
	49	printk(KERN_WARNING "%s: Attempt to poll on zombified "
	50	"daemon\n", __func__);
	51	goto out_unlock_daemon;
	52	}
	53	if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
	54	goto out_unlock_daemon;
	55	if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
	56	goto out_unlock_daemon;
	57	daemon->flags \|= ECRYPTFS_DAEMON_IN_POLL;
	58	mutex_unlock(&daemon->mux);
	59	poll_wait(file, &daemon->wait, pt);
	60	mutex_lock(&daemon->mux);
	61	if (!list_empty(&daemon->msg_ctx_out_queue))
	62	mask \|= POLLIN \| POLLRDNORM;
	63	out_unlock_daemon:
	64	daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
	65	mutex_unlock(&daemon->mux);
	66	return mask;
	67	}
	68
	69	/**
	70	* ecryptfs_miscdev_open
	71	* @inode: inode of miscdev handle (ignored)
2ecaf55d	72	* @file: file for miscdev handle
8bf2debd MH	73	*
	74	* Returns zero on success; non-zero otherwise
	75	*/
	76	static int
	77	ecryptfs_miscdev_open(struct inode inode, struct file file)
	78	{
	79	struct ecryptfs_daemon *daemon = NULL;
	80	int rc;
	81
	82	mutex_lock(&ecryptfs_daemon_hash_mux);
2ecaf55d TH	83	rc = ecryptfs_find_daemon_by_euid(&daemon);
2ecaf55d TH	84	if (!rc) {
8bf2debd	85	rc = -EINVAL;
2ecaf55d TH	86	goto out_unlock_daemon_list;
	87	}
	88	rc = ecryptfs_spawn_daemon(&daemon, file);
	89	if (rc) {
	90	printk(KERN_ERR "%s: Error attempting to spawn daemon; "
	91	"rc = [%d]\n", __func__, rc);
52f21999	92	goto out_unlock_daemon_list;
8bf2debd	93	}
2ecaf55d	94	mutex_lock(&daemon->mux);
8bf2debd MH	95	if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
8bf2debd MH	96	rc = -EBUSY;
8bf2debd MH	97	goto out_unlock_daemon;
	98	}
	99	daemon->flags \|= ECRYPTFS_DAEMON_MISCDEV_OPEN;
8dc67805	100	file->private_data = daemon;
8bf2debd MH	101	atomic_inc(&ecryptfs_num_miscdev_opens);
	102	out_unlock_daemon:
	103	mutex_unlock(&daemon->mux);
8bf2debd MH	104	out_unlock_daemon_list:
	105	mutex_unlock(&ecryptfs_daemon_hash_mux);
	106	return rc;
	107	}
	108
	109	/**
	110	* ecryptfs_miscdev_release
	111	* @inode: inode of fs/ecryptfs/euid handle (ignored)
2ecaf55d	112	* @file: file for fs/ecryptfs/euid handle
8bf2debd MH	113	*
	114	* This keeps the daemon registered until the daemon sends another
	115	* ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
	116	*
	117	* Returns zero on success; non-zero otherwise
	118	*/
	119	static int
	120	ecryptfs_miscdev_release(struct inode inode, struct file file)
	121	{
2ecaf55d	122	struct ecryptfs_daemon *daemon = file->private_data;
8bf2debd MH	123	int rc;
8bf2debd MH	124
8bf2debd	125	mutex_lock(&daemon->mux);
8bf2debd MH	126	BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
	127	daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
	128	atomic_dec(&ecryptfs_num_miscdev_opens);
	129	mutex_unlock(&daemon->mux);
2ecaf55d TH	130
2ecaf55d TH	131	mutex_lock(&ecryptfs_daemon_hash_mux);
8bf2debd	132	rc = ecryptfs_exorcise_daemon(daemon);
2ecaf55d	133	mutex_unlock(&ecryptfs_daemon_hash_mux);
8bf2debd MH	134	if (rc) {
	135	printk(KERN_CRIT "%s: Fatal error whilst attempting to "
	136	"shut down daemon; rc = [%d]. Please report this "
	137	"bug.\n", __func__, rc);
	138	BUG();
	139	}
8bf2debd MH	140	return rc;
	141	}
	142
	143	/**
	144	* ecryptfs_send_miscdev
	145	* @data: Data to send to daemon; may be NULL
	146	* @data_size: Amount of data to send to daemon
	147	* @msg_ctx: Message context, which is used to handle the reply. If
	148	* this is NULL, then we do not expect a reply.
	149	* @msg_type: Type of message
	150	* @msg_flags: Flags for message
	151	* @daemon: eCryptfs daemon object
	152	*
	153	* Add msg_ctx to queue and then, if it exists, notify the blocked
	154	* miscdevess about the data being available. Must be called with
	155	* ecryptfs_daemon_hash_mux held.
	156	*
	157	* Returns zero on success; non-zero otherwise
	158	*/
	159	int ecryptfs_send_miscdev(char *data, size_t data_size,
	160	struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
	161	u16 msg_flags, struct ecryptfs_daemon *daemon)
	162	{
60d65f1f	163	struct ecryptfs_message *msg;
8bf2debd	164
60d65f1f	165	msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
1a0bba4f	166	if (!msg)
60d65f1f	167	return -ENOMEM;
60d65f1f TH	168
	169	mutex_lock(&msg_ctx->mux);
	170	msg_ctx->msg = msg;
8bf2debd MH	171	msg_ctx->msg->index = msg_ctx->index;
	172	msg_ctx->msg->data_len = data_size;
	173	msg_ctx->type = msg_type;
57ea34d1 TH	174	memcpy(msg_ctx->msg->data, data, data_size);
57ea34d1 TH	175	msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
8bf2debd	176	list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
60d65f1f TH	177	mutex_unlock(&msg_ctx->mux);
	178
	179	mutex_lock(&daemon->mux);
8bf2debd MH	180	daemon->num_queued_msg_ctx++;
	181	wake_up_interruptible(&daemon->wait);
	182	mutex_unlock(&daemon->mux);
60d65f1f TH	183
60d65f1f TH	184	return 0;
8bf2debd MH	185	}
8bf2debd MH	186
48399c0b TH	187	/*
	188	* miscdevfs packet format:
	189	* Octet 0: Type
	190	* Octets 1-4: network byte order msg_ctx->counter
	191	* Octets 5-N0: Size of struct ecryptfs_message to follow
	192	* Octets N0-N1: struct ecryptfs_message (including data)
	193	*
	194	* Octets 5-N1 not written if the packet type does not include a message
	195	*/
	196	#define PKT_TYPE_SIZE 1
	197	#define PKT_CTR_SIZE 4
	198	#define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
	199	#define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
	200	+ ECRYPTFS_MIN_PKT_LEN_SIZE)
	201	/* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
	202	#define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
	203	+ ECRYPTFS_MAX_PKT_LEN_SIZE \
	204	+ sizeof(struct ecryptfs_message) \
	205	+ 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
	206	#define PKT_TYPE_OFFSET 0
	207	#define PKT_CTR_OFFSET PKT_TYPE_SIZE
	208	#define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
	209
8bf2debd MH	210	/**
8bf2debd MH	211	* ecryptfs_miscdev_read - format and send message from queue
2ecaf55d	212	* @file: miscdevfs handle
8bf2debd MH	213	* @buf: User buffer into which to copy the next message on the daemon queue
	214	* @count: Amount of space available in @buf
	215	* @ppos: Offset in file (ignored)
	216	*
	217	* Pulls the most recent message from the daemon queue, formats it for
	218	* being sent via a miscdevfs handle, and copies it into @buf
	219	*
	220	* Returns the number of bytes copied into the user buffer
	221	*/
f66e883e	222	static ssize_t
8bf2debd MH	223	ecryptfs_miscdev_read(struct file file, char __user buf, size_t count,
	224	loff_t *ppos)
	225	{
2ecaf55d	226	struct ecryptfs_daemon *daemon = file->private_data;
8bf2debd MH	227	struct ecryptfs_msg_ctx *msg_ctx;
8bf2debd MH	228	size_t packet_length_size;
48399c0b	229	char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
8bf2debd MH	230	size_t i;
	231	size_t total_length;
	232	int rc;
	233
8bf2debd MH	234	mutex_lock(&daemon->mux);
	235	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
	236	rc = 0;
	237	printk(KERN_WARNING "%s: Attempt to read from zombified "
	238	"daemon\n", __func__);
	239	goto out_unlock_daemon;
	240	}
	241	if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
	242	rc = 0;
	243	goto out_unlock_daemon;
	244	}
	245	/* This daemon will not go away so long as this flag is set */
	246	daemon->flags \|= ECRYPTFS_DAEMON_IN_READ;
8bf2debd MH	247	check_list:
	248	if (list_empty(&daemon->msg_ctx_out_queue)) {
	249	mutex_unlock(&daemon->mux);
	250	rc = wait_event_interruptible(
	251	daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
	252	mutex_lock(&daemon->mux);
	253	if (rc < 0) {
	254	rc = 0;
	255	goto out_unlock_daemon;
	256	}
	257	}
	258	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
	259	rc = 0;
	260	goto out_unlock_daemon;
	261	}
	262	if (list_empty(&daemon->msg_ctx_out_queue)) {
	263	/* Something else jumped in since the
	264	* wait_event_interruptable() and removed the
	265	* message from the queue; try again */
	266	goto check_list;
	267	}
8bf2debd MH	268	msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
	269	struct ecryptfs_msg_ctx, daemon_out_list);
	270	BUG_ON(!msg_ctx);
	271	mutex_lock(&msg_ctx->mux);
	272	if (msg_ctx->msg) {
	273	rc = ecryptfs_write_packet_length(packet_length,
	274	msg_ctx->msg_size,
	275	&packet_length_size);
	276	if (rc) {
	277	rc = 0;
	278	printk(KERN_WARNING "%s: Error writing packet length; "
	279	"rc = [%d]\n", __func__, rc);
	280	goto out_unlock_msg_ctx;
	281	}
	282	} else {
	283	packet_length_size = 0;
	284	msg_ctx->msg_size = 0;
	285	}
48399c0b TH	286	total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
48399c0b TH	287	+ msg_ctx->msg_size);
8bf2debd MH	288	if (count < total_length) {
	289	rc = 0;
	290	printk(KERN_WARNING "%s: Only given user buffer of "
df261c52	291	"size [%zd], but we need [%zd] to read the "
8bf2debd MH	292	"pending message\n", __func__, count, total_length);
	293	goto out_unlock_msg_ctx;
	294	}
79bc12a0 AV	295	rc = -EFAULT;
	296	if (put_user(msg_ctx->type, buf))
	297	goto out_unlock_msg_ctx;
48399c0b TH	298	if (put_user(cpu_to_be32(msg_ctx->counter),
48399c0b TH	299	(__be32 __user *)(&buf[PKT_CTR_OFFSET])))
79bc12a0	300	goto out_unlock_msg_ctx;
48399c0b	301	i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
8bf2debd	302	if (msg_ctx->msg) {
79bc12a0 AV	303	if (copy_to_user(&buf[i], packet_length, packet_length_size))
79bc12a0 AV	304	goto out_unlock_msg_ctx;
8bf2debd	305	i += packet_length_size;
79bc12a0	306	if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
8bf2debd	307	goto out_unlock_msg_ctx;
8bf2debd MH	308	i += msg_ctx->msg_size;
	309	}
	310	rc = i;
	311	list_del(&msg_ctx->daemon_out_list);
	312	kfree(msg_ctx->msg);
	313	msg_ctx->msg = NULL;
	314	/* We do not expect a reply from the userspace daemon for any
	315	* message type other than ECRYPTFS_MSG_REQUEST */
	316	if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
	317	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	318	out_unlock_msg_ctx:
	319	mutex_unlock(&msg_ctx->mux);
	320	out_unlock_daemon:
	321	daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
	322	mutex_unlock(&daemon->mux);
	323	return rc;
	324	}
	325
8bf2debd MH	326	/**
	327	* ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
	328	* @data: Bytes comprising struct ecryptfs_message
	329	* @data_size: sizeof(struct ecryptfs_message) + data len
8bf2debd MH	330	* @seq: Sequence number for miscdev response packet
	331	*
	332	* Returns zero on success; non-zero otherwise
	333	*/
2ecaf55d TH	334	static int ecryptfs_miscdev_response(struct ecryptfs_daemon daemon, char data,
2ecaf55d TH	335	size_t data_size, u32 seq)
8bf2debd MH	336	{
	337	struct ecryptfs_message msg = (struct ecryptfs_message )data;
	338	int rc;
	339
	340	if ((sizeof(*msg) + msg->data_len) != data_size) {
	341	printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
df261c52	342	"[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
8bf2debd MH	343	(sizeof(*msg) + msg->data_len), data_size);
	344	rc = -EINVAL;
	345	goto out;
	346	}
2ecaf55d	347	rc = ecryptfs_process_response(daemon, msg, seq);
8bf2debd MH	348	if (rc)
	349	printk(KERN_ERR
	350	"Error processing response message; rc = [%d]\n", rc);
	351	out:
	352	return rc;
	353	}
	354
	355	/**
	356	* ecryptfs_miscdev_write - handle write to daemon miscdev handle
2ecaf55d	357	* @file: File for misc dev handle
8bf2debd MH	358	* @buf: Buffer containing user data
	359	* @count: Amount of data in @buf
	360	* @ppos: Pointer to offset in file (ignored)
	361	*
8bf2debd MH	362	* Returns the number of bytes read from @buf
	363	*/
	364	static ssize_t
	365	ecryptfs_miscdev_write(struct file file, const char __user buf,
	366	size_t count, loff_t *ppos)
	367	{
79bc12a0 AV	368	__be32 counter_nbo;
79bc12a0 AV	369	u32 seq;
48399c0b	370	size_t packet_size, packet_size_length;
8bf2debd	371	char *data;
48399c0b	372	unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
7f133504	373	ssize_t rc;
8bf2debd	374
db10e556	375	if (count == 0) {
7f133504	376	return 0;
48399c0b	377	} else if (count == MIN_NON_MSG_PKT_SIZE) {
db10e556 TH	378	/* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
db10e556 TH	379	goto memdup;
48399c0b	380	} else if (count < MIN_MSG_PKT_SIZE \|\| count > MAX_MSG_PKT_SIZE) {
db10e556	381	printk(KERN_WARNING "%s: Acceptable packet size range is "
0996b67d	382	"[%d-%zu], but amount of data written is [%zu].\n",
48399c0b	383	__func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
db10e556 TH	384	return -EINVAL;
	385	}
	386
48399c0b	387	if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
db10e556 TH	388	sizeof(packet_size_peek))) {
	389	printk(KERN_WARNING "%s: Error while inspecting packet size\n",
	390	__func__);
	391	return -EFAULT;
	392	}
	393
	394	rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
	395	&packet_size_length);
	396	if (rc) {
	397	printk(KERN_WARNING "%s: Error parsing packet length; "
7f133504	398	"rc = [%zd]\n", __func__, rc);
db10e556 TH	399	return rc;
	400	}
	401
48399c0b TH	402	if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
48399c0b TH	403	!= count) {
db10e556 TH	404	printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
	405	packet_size);
	406	return -EINVAL;
	407	}
fd56d242	408
db10e556	409	memdup:
fd56d242 LZ	410	data = memdup_user(buf, count);
	411	if (IS_ERR(data)) {
	412	printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
	413	__func__, PTR_ERR(data));
7f133504	414	return PTR_ERR(data);
8bf2debd	415	}
48399c0b	416	switch (data[PKT_TYPE_OFFSET]) {
8bf2debd	417	case ECRYPTFS_MSG_RESPONSE:
48399c0b TH	418	if (count < (MIN_MSG_PKT_SIZE
48399c0b TH	419	+ sizeof(struct ecryptfs_message))) {
8bf2debd	420	printk(KERN_WARNING "%s: Minimum acceptable packet "
df261c52 MH	421	"size is [%zd], but amount of data written is "
df261c52 MH	422	"only [%zd]. Discarding response packet.\n",
8bf2debd	423	__func__,
48399c0b TH	424	(MIN_MSG_PKT_SIZE
48399c0b TH	425	+ sizeof(struct ecryptfs_message)), count);
7f133504	426	rc = -EINVAL;
8bf2debd MH	427	goto out_free;
8bf2debd MH	428	}
48399c0b	429	memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
8bf2debd	430	seq = be32_to_cpu(counter_nbo);
2ecaf55d	431	rc = ecryptfs_miscdev_response(file->private_data,
48399c0b	432	&data[PKT_LEN_OFFSET + packet_size_length],
2ecaf55d	433	packet_size, seq);
7f133504	434	if (rc) {
8bf2debd	435	printk(KERN_WARNING "%s: Failed to deliver miscdev "
7f133504	436	"response to requesting operation; rc = [%zd]\n",
8bf2debd	437	__func__, rc);
7f133504 TH	438	goto out_free;
7f133504 TH	439	}
8bf2debd MH	440	break;
8bf2debd MH	441	case ECRYPTFS_MSG_HELO:
8bf2debd	442	case ECRYPTFS_MSG_QUIT:
8bf2debd MH	443	break;
	444	default:
	445	ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
	446	"message of unrecognized type [%d]\n",
	447	data[0]);
7f133504 TH	448	rc = -EINVAL;
7f133504 TH	449	goto out_free;
8bf2debd	450	}
7f133504	451	rc = count;
8bf2debd MH	452	out_free:
8bf2debd MH	453	kfree(data);
7f133504	454	return rc;
8bf2debd MH	455	}
	456
	457
	458	static const struct file_operations ecryptfs_miscdev_fops = {
52f21999	459	.owner = THIS_MODULE,
8bf2debd MH	460	.open = ecryptfs_miscdev_open,
	461	.poll = ecryptfs_miscdev_poll,
	462	.read = ecryptfs_miscdev_read,
	463	.write = ecryptfs_miscdev_write,
	464	.release = ecryptfs_miscdev_release,
6038f373	465	.llseek = noop_llseek,
8bf2debd MH	466	};
	467
	468	static struct miscdevice ecryptfs_miscdev = {
	469	.minor = MISC_DYNAMIC_MINOR,
	470	.name = "ecryptfs",
	471	.fops = &ecryptfs_miscdev_fops
	472	};
	473
	474	/**
	475	* ecryptfs_init_ecryptfs_miscdev
	476	*
	477	* Messages sent to the userspace daemon from the kernel are placed on
	478	* a queue associated with the daemon. The next read against the
	479	* miscdev handle by that daemon will return the oldest message placed
	480	* on the message queue for the daemon.
	481	*
	482	* Returns zero on success; non-zero otherwise
	483	*/
7371a382	484	int __init ecryptfs_init_ecryptfs_miscdev(void)
8bf2debd MH	485	{
	486	int rc;
	487
	488	atomic_set(&ecryptfs_num_miscdev_opens, 0);
8bf2debd MH	489	rc = misc_register(&ecryptfs_miscdev);
	490	if (rc)
	491	printk(KERN_ERR "%s: Failed to register miscellaneous device "
	492	"for communications with userspace daemons; rc = [%d]\n",
	493	__func__, rc);
8bf2debd MH	494	return rc;
	495	}
	496
	497	/**
	498	* ecryptfs_destroy_ecryptfs_miscdev
	499	*
	500	* All of the daemons must be exorcised prior to calling this
	501	* function.
	502	*/
	503	void ecryptfs_destroy_ecryptfs_miscdev(void)
	504	{
	505	BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0);
	506	misc_deregister(&ecryptfs_miscdev);
	507	}