[linux.git] / fs / ecryptfs / messaging.c

/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2004-2008 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <[email protected]>
 *		Tyler Hicks <[email protected]>
 *
 * 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/sched.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include <linux/nsproxy.h>
#include "ecryptfs_kernel.h"

static LIST_HEAD(ecryptfs_msg_ctx_free_list);
static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
static struct mutex ecryptfs_msg_ctx_lists_mux;

static struct hlist_head *ecryptfs_daemon_hash;
struct mutex ecryptfs_daemon_hash_mux;
static int ecryptfs_hash_bits;
#define ecryptfs_current_euid_hash(uid) \
	hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)

static u32 ecryptfs_msg_counter;
static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;

/**
 * ecryptfs_acquire_free_msg_ctx
 * @msg_ctx: The context that was acquired from the free list
 *
 * Acquires a context element from the free list and locks the mutex
 * on the context.  Sets the msg_ctx task to current.  Returns zero on
 * success; non-zero on error or upon failure to acquire a free
 * context element.  Must be called with ecryptfs_msg_ctx_lists_mux
 * held.
 */
static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
{
	struct list_head *p;
	int rc;

	if (list_empty(&ecryptfs_msg_ctx_free_list)) {
		printk(KERN_WARNING "%s: The eCryptfs free "
		       "context list is empty.  It may be helpful to "
		       "specify the ecryptfs_message_buf_len "
		       "parameter to be greater than the current "
		       "value of [%d]\n", __func__, ecryptfs_message_buf_len);
		rc = -ENOMEM;
		goto out;
	}
	list_for_each(p, &ecryptfs_msg_ctx_free_list) {
		*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
		if (mutex_trylock(&(*msg_ctx)->mux)) {
			(*msg_ctx)->task = current;
			rc = 0;
			goto out;
		}
	}
	rc = -ENOMEM;
out:
	return rc;
}

/**
 * ecryptfs_msg_ctx_free_to_alloc
 * @msg_ctx: The context to move from the free list to the alloc list
 *
 * Must be called with ecryptfs_msg_ctx_lists_mux held.
 */
static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
{
	list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
	msg_ctx->counter = ++ecryptfs_msg_counter;
}

/**
 * ecryptfs_msg_ctx_alloc_to_free
 * @msg_ctx: The context to move from the alloc list to the free list
 *
 * Must be called with ecryptfs_msg_ctx_lists_mux held.
 */
void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
{
	list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
	kfree(msg_ctx->msg);
	msg_ctx->msg = NULL;
	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
}

/**
 * ecryptfs_find_daemon_by_euid
 * @daemon: If return value is zero, points to the desired daemon pointer
 *
 * Must be called with ecryptfs_daemon_hash_mux held.
 *
 * Search the hash list for the current effective user id.
 *
 * Returns zero if the user id exists in the list; non-zero otherwise.
 */
int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
{
	int rc;

	hlist_for_each_entry(*daemon,
			    &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
			    euid_chain) {
		if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
			rc = 0;
			goto out;
		}
	}
	rc = -EINVAL;
out:
	return rc;
}

/**
 * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
 * @daemon: Pointer to set to newly allocated daemon struct
 * @file: File used when opening /dev/ecryptfs
 *
 * Must be called ceremoniously while in possession of
 * ecryptfs_sacred_daemon_hash_mux
 *
 * Returns zero on success; non-zero otherwise
 */
int
ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file)
{
	int rc = 0;

	(*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
	if (!(*daemon)) {
		rc = -ENOMEM;
		goto out;
	}
	(*daemon)->file = file;
	mutex_init(&(*daemon)->mux);
	INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
	init_waitqueue_head(&(*daemon)->wait);
	(*daemon)->num_queued_msg_ctx = 0;
	hlist_add_head(&(*daemon)->euid_chain,
		       &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]);
out:
	return rc;
}

/**
 * ecryptfs_exorcise_daemon - Destroy the daemon struct
 *
 * Must be called ceremoniously while in possession of
 * ecryptfs_daemon_hash_mux and the daemon's own mux.
 */
int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
{
	struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp;
	int rc = 0;

	mutex_lock(&daemon->mux);
	if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
	    || (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
		rc = -EBUSY;
		mutex_unlock(&daemon->mux);
		goto out;
	}
	list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
				 &daemon->msg_ctx_out_queue, daemon_out_list) {
		list_del(&msg_ctx->daemon_out_list);
		daemon->num_queued_msg_ctx--;
		printk(KERN_WARNING "%s: Warning: dropping message that is in "
		       "the out queue of a dying daemon\n", __func__);
		ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	}
	hlist_del(&daemon->euid_chain);
	mutex_unlock(&daemon->mux);
	kzfree(daemon);
out:
	return rc;
}

/**
 * ecryptfs_process_reponse
 * @msg: The ecryptfs message received; the caller should sanity check
 *       msg->data_len and free the memory
 * @seq: The sequence number of the message; must match the sequence
 *       number for the existing message context waiting for this
 *       response
 *
 * Processes a response message after sending an operation request to
 * userspace. Some other process is awaiting this response. Before
 * sending out its first communications, the other process allocated a
 * msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
 * response message contains this index so that we can copy over the
 * response message into the msg_ctx that the process holds a
 * reference to. The other process is going to wake up, check to see
 * that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
 * proceed to read off and process the response message. Returns zero
 * upon delivery to desired context element; non-zero upon delivery
 * failure or error.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
			      struct ecryptfs_message *msg, u32 seq)
{
	struct ecryptfs_msg_ctx *msg_ctx;
	size_t msg_size;
	int rc;

	if (msg->index >= ecryptfs_message_buf_len) {
		rc = -EINVAL;
		printk(KERN_ERR "%s: Attempt to reference "
		       "context buffer at index [%d]; maximum "
		       "allowable is [%d]\n", __func__, msg->index,
		       (ecryptfs_message_buf_len - 1));
		goto out;
	}
	msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
	mutex_lock(&msg_ctx->mux);
	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
		rc = -EINVAL;
		printk(KERN_WARNING "%s: Desired context element is not "
		       "pending a response\n", __func__);
		goto unlock;
	} else if (msg_ctx->counter != seq) {
		rc = -EINVAL;
		printk(KERN_WARNING "%s: Invalid message sequence; "
		       "expected [%d]; received [%d]\n", __func__,
		       msg_ctx->counter, seq);
		goto unlock;
	}
	msg_size = (sizeof(*msg) + msg->data_len);
	msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
	if (!msg_ctx->msg) {
		rc = -ENOMEM;
		goto unlock;
	}
	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
	wake_up_process(msg_ctx->task);
	rc = 0;
unlock:
	mutex_unlock(&msg_ctx->mux);
out:
	return rc;
}

/**
 * ecryptfs_send_message_locked
 * @data: The data to send
 * @data_len: The length of data
 * @msg_ctx: The message context allocated for the send
 *
 * Must be called with ecryptfs_daemon_hash_mux held.
 *
 * Returns zero on success; non-zero otherwise
 */
static int
ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
			     struct ecryptfs_msg_ctx **msg_ctx)
{
	struct ecryptfs_daemon *daemon;
	int rc;

	rc = ecryptfs_find_daemon_by_euid(&daemon);
	if (rc) {
		rc = -ENOTCONN;
		goto out;
	}
	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
	if (rc) {
		mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
		printk(KERN_WARNING "%s: Could not claim a free "
		       "context element\n", __func__);
		goto out;
	}
	ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
	mutex_unlock(&(*msg_ctx)->mux);
	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
				   daemon);
	if (rc)
		printk(KERN_ERR "%s: Error attempting to send message to "
		       "userspace daemon; rc = [%d]\n", __func__, rc);
out:
	return rc;
}

/**
 * ecryptfs_send_message
 * @data: The data to send
 * @data_len: The length of data
 * @msg_ctx: The message context allocated for the send
 *
 * Grabs ecryptfs_daemon_hash_mux.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_send_message(char *data, int data_len,
			  struct ecryptfs_msg_ctx **msg_ctx)
{
	int rc;

	mutex_lock(&ecryptfs_daemon_hash_mux);
	rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
					  msg_ctx);
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	return rc;
}

/**
 * ecryptfs_wait_for_response
 * @msg_ctx: The context that was assigned when sending a message
 * @msg: The incoming message from userspace; not set if rc != 0
 *
 * Sleeps until awaken by ecryptfs_receive_message or until the amount
 * of time exceeds ecryptfs_message_wait_timeout.  If zero is
 * returned, msg will point to a valid message from userspace; a
 * non-zero value is returned upon failure to receive a message or an
 * error occurs. Callee must free @msg on success.
 */
int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
			       struct ecryptfs_message **msg)
{
	signed long timeout = ecryptfs_message_wait_timeout * HZ;
	int rc = 0;

sleep:
	timeout = schedule_timeout_interruptible(timeout);
	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	mutex_lock(&msg_ctx->mux);
	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
		if (timeout) {
			mutex_unlock(&msg_ctx->mux);
			mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
			goto sleep;
		}
		rc = -ENOMSG;
	} else {
		*msg = msg_ctx->msg;
		msg_ctx->msg = NULL;
	}
	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	mutex_unlock(&msg_ctx->mux);
	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	return rc;
}

int __init ecryptfs_init_messaging(void)
{
	int i;
	int rc = 0;

	if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
		ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
		printk(KERN_WARNING "%s: Specified number of users is "
		       "too large, defaulting to [%d] users\n", __func__,
		       ecryptfs_number_of_users);
	}
	mutex_init(&ecryptfs_daemon_hash_mux);
	mutex_lock(&ecryptfs_daemon_hash_mux);
	ecryptfs_hash_bits = 1;
	while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
		ecryptfs_hash_bits++;
	ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
					* (1 << ecryptfs_hash_bits)),
				       GFP_KERNEL);
	if (!ecryptfs_daemon_hash) {
		rc = -ENOMEM;
		mutex_unlock(&ecryptfs_daemon_hash_mux);
		goto out;
	}
	for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
		INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
					* ecryptfs_message_buf_len),
				       GFP_KERNEL);
	if (!ecryptfs_msg_ctx_arr) {
		rc = -ENOMEM;
		goto out;
	}
	mutex_init(&ecryptfs_msg_ctx_lists_mux);
	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	ecryptfs_msg_counter = 0;
	for (i = 0; i < ecryptfs_message_buf_len; i++) {
		INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
		INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
		mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
		mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
		ecryptfs_msg_ctx_arr[i].index = i;
		ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
		ecryptfs_msg_ctx_arr[i].counter = 0;
		ecryptfs_msg_ctx_arr[i].task = NULL;
		ecryptfs_msg_ctx_arr[i].msg = NULL;
		list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
			      &ecryptfs_msg_ctx_free_list);
		mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
	}
	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	rc = ecryptfs_init_ecryptfs_miscdev();
	if (rc)
		ecryptfs_release_messaging();
out:
	return rc;
}

void ecryptfs_release_messaging(void)
{
	if (ecryptfs_msg_ctx_arr) {
		int i;

		mutex_lock(&ecryptfs_msg_ctx_lists_mux);
		for (i = 0; i < ecryptfs_message_buf_len; i++) {
			mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
			kfree(ecryptfs_msg_ctx_arr[i].msg);
			mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
		}
		kfree(ecryptfs_msg_ctx_arr);
		mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	}
	if (ecryptfs_daemon_hash) {
		struct ecryptfs_daemon *daemon;
		struct hlist_node *n;
		int i;

		mutex_lock(&ecryptfs_daemon_hash_mux);
		for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
			int rc;

			hlist_for_each_entry_safe(daemon, n,
						  &ecryptfs_daemon_hash[i],
						  euid_chain) {
				rc = ecryptfs_exorcise_daemon(daemon);
				if (rc)
					printk(KERN_ERR "%s: Error whilst "
					       "attempting to destroy daemon; "
					       "rc = [%d]. Dazed and confused, "
					       "but trying to continue.\n",
					       __func__, rc);
			}
		}
		kfree(ecryptfs_daemon_hash);
		mutex_unlock(&ecryptfs_daemon_hash_mux);
	}
	ecryptfs_destroy_ecryptfs_miscdev();
	return;
}
Commit	Line	Data
88b4a07e MH	1	/**
	2	* eCryptfs: Linux filesystem encryption layer
	3	*
f66e883e	4	* Copyright (C) 2004-2008 International Business Machines Corp.
88b4a07e MH	5	* Author(s): Michael A. Halcrow <[email protected]>
	6	* Tyler Hicks <[email protected]>
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License version
	10	* 2 as published by the Free Software Foundation.
	11	*
	12	* This program is distributed in the hope that it will be useful, but
	13	* WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	* General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	20	* 02111-1307, USA.
	21	*/
e8edc6e0	22	#include <linux/sched.h>
5a0e3ad6	23	#include <linux/slab.h>
6a3fd92e MH	24	#include <linux/user_namespace.h>
6a3fd92e MH	25	#include <linux/nsproxy.h>
88b4a07e MH	26	#include "ecryptfs_kernel.h"
88b4a07e MH	27
dd2a3b7a MH	28	static LIST_HEAD(ecryptfs_msg_ctx_free_list);
	29	static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
	30	static struct mutex ecryptfs_msg_ctx_lists_mux;
88b4a07e	31
f66e883e MH	32	static struct hlist_head *ecryptfs_daemon_hash;
f66e883e MH	33	struct mutex ecryptfs_daemon_hash_mux;
a6f80fb7	34	static int ecryptfs_hash_bits;
2ecaf55d	35	#define ecryptfs_current_euid_hash(uid) \
cdf8c58a	36	hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)
88b4a07e	37
f66e883e	38	static u32 ecryptfs_msg_counter;
dd2a3b7a	39	static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
88b4a07e MH	40
	41	/**
	42	* ecryptfs_acquire_free_msg_ctx
	43	* @msg_ctx: The context that was acquired from the free list
	44	*
	45	* Acquires a context element from the free list and locks the mutex
f66e883e MH	46	* on the context. Sets the msg_ctx task to current. Returns zero on
	47	* success; non-zero on error or upon failure to acquire a free
	48	* context element. Must be called with ecryptfs_msg_ctx_lists_mux
	49	* held.
88b4a07e MH	50	*/
	51	static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
	52	{
	53	struct list_head *p;
	54	int rc;
	55
	56	if (list_empty(&ecryptfs_msg_ctx_free_list)) {
f66e883e MH	57	printk(KERN_WARNING "%s: The eCryptfs free "
	58	"context list is empty. It may be helpful to "
	59	"specify the ecryptfs_message_buf_len "
	60	"parameter to be greater than the current "
	61	"value of [%d]\n", __func__, ecryptfs_message_buf_len);
88b4a07e MH	62	rc = -ENOMEM;
	63	goto out;
	64	}
	65	list_for_each(p, &ecryptfs_msg_ctx_free_list) {
	66	*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
	67	if (mutex_trylock(&(*msg_ctx)->mux)) {
	68	(*msg_ctx)->task = current;
	69	rc = 0;
	70	goto out;
	71	}
	72	}
	73	rc = -ENOMEM;
	74	out:
	75	return rc;
	76	}
	77
	78	/**
	79	* ecryptfs_msg_ctx_free_to_alloc
	80	* @msg_ctx: The context to move from the free list to the alloc list
	81	*
f66e883e	82	* Must be called with ecryptfs_msg_ctx_lists_mux held.
88b4a07e MH	83	*/
	84	static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
	85	{
	86	list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
	87	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
	88	msg_ctx->counter = ++ecryptfs_msg_counter;
	89	}
	90
	91	/**
	92	* ecryptfs_msg_ctx_alloc_to_free
	93	* @msg_ctx: The context to move from the alloc list to the free list
	94	*
f66e883e	95	* Must be called with ecryptfs_msg_ctx_lists_mux held.
88b4a07e	96	*/
f66e883e	97	void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
88b4a07e MH	98	{
88b4a07e MH	99	list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
1101d586	100	kfree(msg_ctx->msg);
f66e883e	101	msg_ctx->msg = NULL;
88b4a07e MH	102	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
	103	}
	104
	105	/**
f66e883e	106	* ecryptfs_find_daemon_by_euid
f66e883e	107	* @daemon: If return value is zero, points to the desired daemon pointer
88b4a07e	108	*
f66e883e MH	109	* Must be called with ecryptfs_daemon_hash_mux held.
f66e883e MH	110	*
2ecaf55d	111	* Search the hash list for the current effective user id.
f66e883e MH	112	*
f66e883e MH	113	* Returns zero if the user id exists in the list; non-zero otherwise.
88b4a07e	114	*/
2ecaf55d	115	int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
88b4a07e	116	{
88b4a07e MH	117	int rc;
88b4a07e MH	118
b67bfe0d	119	hlist_for_each_entry(*daemon,
2ecaf55d TH	120	&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
2ecaf55d TH	121	euid_chain) {
cdf8c58a	122	if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
88b4a07e MH	123	rc = 0;
	124	goto out;
	125	}
	126	}
	127	rc = -EINVAL;
	128	out:
	129	return rc;
	130	}
	131
f66e883e MH	132	/**
	133	* ecryptfs_spawn_daemon - Create and initialize a new daemon struct
	134	* @daemon: Pointer to set to newly allocated daemon struct
2ecaf55d	135	* @file: File used when opening /dev/ecryptfs
f66e883e MH	136	*
	137	* Must be called ceremoniously while in possession of
	138	* ecryptfs_sacred_daemon_hash_mux
	139	*
	140	* Returns zero on success; non-zero otherwise
	141	*/
	142	int
2ecaf55d	143	ecryptfs_spawn_daemon(struct ecryptfs_daemon *daemon, struct file file)
f66e883e MH	144	{
	145	int rc = 0;
	146
	147	(daemon) = kzalloc(sizeof(*daemon), GFP_KERNEL);
	148	if (!(*daemon)) {
	149	rc = -ENOMEM;
f66e883e MH	150	goto out;
f66e883e MH	151	}
2ecaf55d	152	(*daemon)->file = file;
f66e883e MH	153	mutex_init(&(*daemon)->mux);
	154	INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
	155	init_waitqueue_head(&(*daemon)->wait);
	156	(*daemon)->num_queued_msg_ctx = 0;
	157	hlist_add_head(&(*daemon)->euid_chain,
2ecaf55d	158	&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]);
f66e883e	159	out:
88b4a07e MH	160	return rc;
	161	}
	162
f66e883e MH	163	/**
	164	* ecryptfs_exorcise_daemon - Destroy the daemon struct
	165	*
	166	* Must be called ceremoniously while in possession of
	167	* ecryptfs_daemon_hash_mux and the daemon's own mux.
	168	*/
	169	int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
	170	{
	171	struct ecryptfs_msg_ctx msg_ctx, msg_ctx_tmp;
	172	int rc = 0;
	173
	174	mutex_lock(&daemon->mux);
	175	if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
	176	\|\| (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
	177	rc = -EBUSY;
f66e883e MH	178	mutex_unlock(&daemon->mux);
	179	goto out;
	180	}
	181	list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
	182	&daemon->msg_ctx_out_queue, daemon_out_list) {
	183	list_del(&msg_ctx->daemon_out_list);
	184	daemon->num_queued_msg_ctx--;
	185	printk(KERN_WARNING "%s: Warning: dropping message that is in "
	186	"the out queue of a dying daemon\n", __func__);
	187	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	188	}
	189	hlist_del(&daemon->euid_chain);
f66e883e	190	mutex_unlock(&daemon->mux);
00fcf2cb	191	kzfree(daemon);
f66e883e	192	out:
88b4a07e MH	193	return rc;
	194	}
	195
88b4a07e MH	196	/**
	197	* ecryptfs_process_reponse
	198	* @msg: The ecryptfs message received; the caller should sanity check
f66e883e	199	* msg->data_len and free the memory
f66e883e MH	200	* @seq: The sequence number of the message; must match the sequence
	201	* number for the existing message context waiting for this
	202	* response
	203	*
	204	* Processes a response message after sending an operation request to
	205	* userspace. Some other process is awaiting this response. Before
	206	* sending out its first communications, the other process allocated a
	207	* msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
	208	* response message contains this index so that we can copy over the
	209	* response message into the msg_ctx that the process holds a
	210	* reference to. The other process is going to wake up, check to see
	211	* that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
	212	* proceed to read off and process the response message. Returns zero
	213	* upon delivery to desired context element; non-zero upon delivery
	214	* failure or error.
88b4a07e	215	*
f66e883e	216	* Returns zero on success; non-zero otherwise
88b4a07e	217	*/
2ecaf55d TH	218	int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
2ecaf55d TH	219	struct ecryptfs_message *msg, u32 seq)
88b4a07e	220	{
88b4a07e	221	struct ecryptfs_msg_ctx *msg_ctx;
f66e883e	222	size_t msg_size;
88b4a07e MH	223	int rc;
	224
	225	if (msg->index >= ecryptfs_message_buf_len) {
	226	rc = -EINVAL;
f66e883e MH	227	printk(KERN_ERR "%s: Attempt to reference "
	228	"context buffer at index [%d]; maximum "
	229	"allowable is [%d]\n", __func__, msg->index,
	230	(ecryptfs_message_buf_len - 1));
88b4a07e MH	231	goto out;
	232	}
	233	msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
	234	mutex_lock(&msg_ctx->mux);
88b4a07e MH	235	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
88b4a07e MH	236	rc = -EINVAL;
f66e883e MH	237	printk(KERN_WARNING "%s: Desired context element is not "
f66e883e MH	238	"pending a response\n", __func__);
88b4a07e MH	239	goto unlock;
	240	} else if (msg_ctx->counter != seq) {
	241	rc = -EINVAL;
f66e883e MH	242	printk(KERN_WARNING "%s: Invalid message sequence; "
	243	"expected [%d]; received [%d]\n", __func__,
	244	msg_ctx->counter, seq);
88b4a07e MH	245	goto unlock;
88b4a07e MH	246	}
f66e883e	247	msg_size = (sizeof(*msg) + msg->data_len);
fc8b14d3	248	msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
88b4a07e MH	249	if (!msg_ctx->msg) {
88b4a07e MH	250	rc = -ENOMEM;
88b4a07e MH	251	goto unlock;
88b4a07e MH	252	}
88b4a07e	253	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
88b4a07e	254	wake_up_process(msg_ctx->task);
2ecaf55d	255	rc = 0;
88b4a07e MH	256	unlock:
	257	mutex_unlock(&msg_ctx->mux);
	258	out:
	259	return rc;
	260	}
	261
	262	/**
f66e883e	263	* ecryptfs_send_message_locked
88b4a07e MH	264	* @data: The data to send
	265	* @data_len: The length of data
	266	* @msg_ctx: The message context allocated for the send
f66e883e MH	267	*
	268	* Must be called with ecryptfs_daemon_hash_mux held.
	269	*
	270	* Returns zero on success; non-zero otherwise
88b4a07e	271	*/
f66e883e	272	static int
624ae528 TH	273	ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
624ae528 TH	274	struct ecryptfs_msg_ctx **msg_ctx)
88b4a07e	275	{
f66e883e	276	struct ecryptfs_daemon *daemon;
88b4a07e MH	277	int rc;
88b4a07e MH	278
2ecaf55d	279	rc = ecryptfs_find_daemon_by_euid(&daemon);
1111eae9	280	if (rc) {
88b4a07e	281	rc = -ENOTCONN;
88b4a07e MH	282	goto out;
88b4a07e MH	283	}
88b4a07e MH	284	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	285	rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
	286	if (rc) {
	287	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
f66e883e MH	288	printk(KERN_WARNING "%s: Could not claim a free "
f66e883e MH	289	"context element\n", __func__);
88b4a07e MH	290	goto out;
	291	}
	292	ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
	293	mutex_unlock(&(*msg_ctx)->mux);
	294	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
624ae528 TH	295	rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
624ae528 TH	296	daemon);
f66e883e MH	297	if (rc)
	298	printk(KERN_ERR "%s: Error attempting to send message to "
	299	"userspace daemon; rc = [%d]\n", __func__, rc);
88b4a07e MH	300	out:
	301	return rc;
	302	}
	303
f66e883e MH	304	/**
f66e883e MH	305	* ecryptfs_send_message
f66e883e MH	306	* @data: The data to send
	307	* @data_len: The length of data
	308	* @msg_ctx: The message context allocated for the send
	309	*
	310	* Grabs ecryptfs_daemon_hash_mux.
	311	*
	312	* Returns zero on success; non-zero otherwise
	313	*/
624ae528	314	int ecryptfs_send_message(char *data, int data_len,
f66e883e MH	315	struct ecryptfs_msg_ctx **msg_ctx)
	316	{
	317	int rc;
	318
	319	mutex_lock(&ecryptfs_daemon_hash_mux);
624ae528 TH	320	rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
624ae528 TH	321	msg_ctx);
f66e883e MH	322	mutex_unlock(&ecryptfs_daemon_hash_mux);
	323	return rc;
	324	}
	325
88b4a07e MH	326	/**
	327	* ecryptfs_wait_for_response
	328	* @msg_ctx: The context that was assigned when sending a message
	329	* @msg: The incoming message from userspace; not set if rc != 0
	330	*
	331	* Sleeps until awaken by ecryptfs_receive_message or until the amount
	332	* of time exceeds ecryptfs_message_wait_timeout. If zero is
	333	* returned, msg will point to a valid message from userspace; a
	334	* non-zero value is returned upon failure to receive a message or an
f66e883e	335	* error occurs. Callee must free @msg on success.
88b4a07e MH	336	*/
	337	int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
	338	struct ecryptfs_message **msg)
	339	{
	340	signed long timeout = ecryptfs_message_wait_timeout * HZ;
	341	int rc = 0;
	342
	343	sleep:
	344	timeout = schedule_timeout_interruptible(timeout);
	345	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	346	mutex_lock(&msg_ctx->mux);
	347	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
	348	if (timeout) {
	349	mutex_unlock(&msg_ctx->mux);
	350	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	351	goto sleep;
	352	}
	353	rc = -ENOMSG;
	354	} else {
	355	*msg = msg_ctx->msg;
	356	msg_ctx->msg = NULL;
	357	}
	358	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	359	mutex_unlock(&msg_ctx->mux);
	360	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	361	return rc;
	362	}
	363
7371a382	364	int __init ecryptfs_init_messaging(void)
88b4a07e MH	365	{
	366	int i;
	367	int rc = 0;
	368
	369	if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
	370	ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
f66e883e MH	371	printk(KERN_WARNING "%s: Specified number of users is "
	372	"too large, defaulting to [%d] users\n", __func__,
	373	ecryptfs_number_of_users);
88b4a07e	374	}
f66e883e MH	375	mutex_init(&ecryptfs_daemon_hash_mux);
f66e883e MH	376	mutex_lock(&ecryptfs_daemon_hash_mux);
a6f80fb7 AO	377	ecryptfs_hash_bits = 1;
	378	while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
	379	ecryptfs_hash_bits++;
f66e883e	380	ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
a6f80fb7 AO	381	* (1 << ecryptfs_hash_bits)),
a6f80fb7 AO	382	GFP_KERNEL);
f66e883e	383	if (!ecryptfs_daemon_hash) {
88b4a07e	384	rc = -ENOMEM;
f66e883e	385	mutex_unlock(&ecryptfs_daemon_hash_mux);
88b4a07e MH	386	goto out;
88b4a07e MH	387	}
a6f80fb7	388	for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
f66e883e MH	389	INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
f66e883e MH	390	mutex_unlock(&ecryptfs_daemon_hash_mux);
88b4a07e	391	ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
f66e883e MH	392	* ecryptfs_message_buf_len),
f66e883e MH	393	GFP_KERNEL);
88b4a07e MH	394	if (!ecryptfs_msg_ctx_arr) {
88b4a07e MH	395	rc = -ENOMEM;
88b4a07e MH	396	goto out;
	397	}
	398	mutex_init(&ecryptfs_msg_ctx_lists_mux);
	399	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	400	ecryptfs_msg_counter = 0;
	401	for (i = 0; i < ecryptfs_message_buf_len; i++) {
	402	INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
f66e883e	403	INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
88b4a07e MH	404	mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
	405	mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
	406	ecryptfs_msg_ctx_arr[i].index = i;
	407	ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
	408	ecryptfs_msg_ctx_arr[i].counter = 0;
	409	ecryptfs_msg_ctx_arr[i].task = NULL;
	410	ecryptfs_msg_ctx_arr[i].msg = NULL;
	411	list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
	412	&ecryptfs_msg_ctx_free_list);
	413	mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
	414	}
	415	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
624ae528 TH	416	rc = ecryptfs_init_ecryptfs_miscdev();
	417	if (rc)
	418	ecryptfs_release_messaging();
88b4a07e MH	419	out:
	420	return rc;
	421	}
	422
624ae528	423	void ecryptfs_release_messaging(void)
88b4a07e MH	424	{
	425	if (ecryptfs_msg_ctx_arr) {
	426	int i;
	427
	428	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	429	for (i = 0; i < ecryptfs_message_buf_len; i++) {
	430	mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
3db593e8	431	kfree(ecryptfs_msg_ctx_arr[i].msg);
88b4a07e MH	432	mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
	433	}
	434	kfree(ecryptfs_msg_ctx_arr);
	435	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	436	}
f66e883e	437	if (ecryptfs_daemon_hash) {
f66e883e	438	struct ecryptfs_daemon *daemon;
db86be3a	439	struct hlist_node *n;
88b4a07e MH	440	int i;
88b4a07e MH	441
f66e883e	442	mutex_lock(&ecryptfs_daemon_hash_mux);
a6f80fb7	443	for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
f66e883e MH	444	int rc;
f66e883e MH	445
db86be3a DC	446	hlist_for_each_entry_safe(daemon, n,
	447	&ecryptfs_daemon_hash[i],
	448	euid_chain) {
f66e883e MH	449	rc = ecryptfs_exorcise_daemon(daemon);
	450	if (rc)
	451	printk(KERN_ERR "%s: Error whilst "
	452	"attempting to destroy daemon; "
	453	"rc = [%d]. Dazed and confused, "
	454	"but trying to continue.\n",
	455	__func__, rc);
88b4a07e MH	456	}
88b4a07e MH	457	}
f66e883e MH	458	kfree(ecryptfs_daemon_hash);
f66e883e MH	459	mutex_unlock(&ecryptfs_daemon_hash_mux);
88b4a07e	460	}
624ae528	461	ecryptfs_destroy_ecryptfs_miscdev();
88b4a07e MH	462	return;
88b4a07e MH	463	}