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

// SPDX-License-Identifier: GPL-2.0-only
/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2004-2008 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
 *		Tyler Hicks <tyhicks@ou.edu>
 */
#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
45051539	1	// SPDX-License-Identifier: GPL-2.0-only
88b4a07e MH	2	/**
	3	* eCryptfs: Linux filesystem encryption layer
	4	*
f66e883e	5	* Copyright (C) 2004-2008 International Business Machines Corp.
88b4a07e MH	6	* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
88b4a07e MH	7	* Tyler Hicks <tyhicks@ou.edu>
88b4a07e	8	*/
e8edc6e0	9	#include <linux/sched.h>
5a0e3ad6	10	#include <linux/slab.h>
6a3fd92e MH	11	#include <linux/user_namespace.h>
6a3fd92e MH	12	#include <linux/nsproxy.h>
88b4a07e MH	13	#include "ecryptfs_kernel.h"
88b4a07e MH	14
dd2a3b7a MH	15	static LIST_HEAD(ecryptfs_msg_ctx_free_list);
	16	static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
	17	static struct mutex ecryptfs_msg_ctx_lists_mux;
88b4a07e	18
f66e883e MH	19	static struct hlist_head *ecryptfs_daemon_hash;
f66e883e MH	20	struct mutex ecryptfs_daemon_hash_mux;
a6f80fb7	21	static int ecryptfs_hash_bits;
2ecaf55d	22	#define ecryptfs_current_euid_hash(uid) \
cdf8c58a	23	hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)
88b4a07e	24
f66e883e	25	static u32 ecryptfs_msg_counter;
dd2a3b7a	26	static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
88b4a07e MH	27
	28	/**
	29	* ecryptfs_acquire_free_msg_ctx
	30	* @msg_ctx: The context that was acquired from the free list
	31	*
	32	* Acquires a context element from the free list and locks the mutex
f66e883e MH	33	* on the context. Sets the msg_ctx task to current. Returns zero on
	34	* success; non-zero on error or upon failure to acquire a free
	35	* context element. Must be called with ecryptfs_msg_ctx_lists_mux
	36	* held.
88b4a07e MH	37	*/
	38	static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
	39	{
	40	struct list_head *p;
	41	int rc;
	42
	43	if (list_empty(&ecryptfs_msg_ctx_free_list)) {
f66e883e MH	44	printk(KERN_WARNING "%s: The eCryptfs free "
	45	"context list is empty. It may be helpful to "
	46	"specify the ecryptfs_message_buf_len "
	47	"parameter to be greater than the current "
	48	"value of [%d]\n", __func__, ecryptfs_message_buf_len);
88b4a07e MH	49	rc = -ENOMEM;
	50	goto out;
	51	}
	52	list_for_each(p, &ecryptfs_msg_ctx_free_list) {
	53	*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
	54	if (mutex_trylock(&(*msg_ctx)->mux)) {
	55	(*msg_ctx)->task = current;
	56	rc = 0;
	57	goto out;
	58	}
	59	}
	60	rc = -ENOMEM;
	61	out:
	62	return rc;
	63	}
	64
	65	/**
	66	* ecryptfs_msg_ctx_free_to_alloc
	67	* @msg_ctx: The context to move from the free list to the alloc list
	68	*
f66e883e	69	* Must be called with ecryptfs_msg_ctx_lists_mux held.
88b4a07e MH	70	*/
	71	static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
	72	{
	73	list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
	74	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
	75	msg_ctx->counter = ++ecryptfs_msg_counter;
	76	}
	77
	78	/**
	79	* ecryptfs_msg_ctx_alloc_to_free
	80	* @msg_ctx: The context to move from the alloc list to the free list
	81	*
f66e883e	82	* Must be called with ecryptfs_msg_ctx_lists_mux held.
88b4a07e	83	*/
f66e883e	84	void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
88b4a07e MH	85	{
88b4a07e MH	86	list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
1101d586	87	kfree(msg_ctx->msg);
f66e883e	88	msg_ctx->msg = NULL;
88b4a07e MH	89	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
	90	}
	91
	92	/**
f66e883e	93	* ecryptfs_find_daemon_by_euid
f66e883e	94	* @daemon: If return value is zero, points to the desired daemon pointer
88b4a07e	95	*
f66e883e MH	96	* Must be called with ecryptfs_daemon_hash_mux held.
f66e883e MH	97	*
2ecaf55d	98	* Search the hash list for the current effective user id.
f66e883e MH	99	*
f66e883e MH	100	* Returns zero if the user id exists in the list; non-zero otherwise.
88b4a07e	101	*/
2ecaf55d	102	int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
88b4a07e	103	{
88b4a07e MH	104	int rc;
88b4a07e MH	105
b67bfe0d	106	hlist_for_each_entry(*daemon,
2ecaf55d TH	107	&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
2ecaf55d TH	108	euid_chain) {
cdf8c58a	109	if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
88b4a07e MH	110	rc = 0;
	111	goto out;
	112	}
	113	}
	114	rc = -EINVAL;
	115	out:
	116	return rc;
	117	}
	118
f66e883e MH	119	/**
	120	* ecryptfs_spawn_daemon - Create and initialize a new daemon struct
	121	* @daemon: Pointer to set to newly allocated daemon struct
2ecaf55d	122	* @file: File used when opening /dev/ecryptfs
f66e883e MH	123	*
	124	* Must be called ceremoniously while in possession of
	125	* ecryptfs_sacred_daemon_hash_mux
	126	*
	127	* Returns zero on success; non-zero otherwise
	128	*/
	129	int
2ecaf55d	130	ecryptfs_spawn_daemon(struct ecryptfs_daemon *daemon, struct file file)
f66e883e MH	131	{
	132	int rc = 0;
	133
	134	(daemon) = kzalloc(sizeof(*daemon), GFP_KERNEL);
	135	if (!(*daemon)) {
	136	rc = -ENOMEM;
f66e883e MH	137	goto out;
f66e883e MH	138	}
2ecaf55d	139	(*daemon)->file = file;
f66e883e MH	140	mutex_init(&(*daemon)->mux);
	141	INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
	142	init_waitqueue_head(&(*daemon)->wait);
	143	(*daemon)->num_queued_msg_ctx = 0;
	144	hlist_add_head(&(*daemon)->euid_chain,
2ecaf55d	145	&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]);
f66e883e	146	out:
88b4a07e MH	147	return rc;
	148	}
	149
f66e883e MH	150	/**
	151	* ecryptfs_exorcise_daemon - Destroy the daemon struct
	152	*
	153	* Must be called ceremoniously while in possession of
	154	* ecryptfs_daemon_hash_mux and the daemon's own mux.
	155	*/
	156	int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
	157	{
	158	struct ecryptfs_msg_ctx msg_ctx, msg_ctx_tmp;
	159	int rc = 0;
	160
	161	mutex_lock(&daemon->mux);
	162	if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
	163	\|\| (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
	164	rc = -EBUSY;
f66e883e MH	165	mutex_unlock(&daemon->mux);
	166	goto out;
	167	}
	168	list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
	169	&daemon->msg_ctx_out_queue, daemon_out_list) {
	170	list_del(&msg_ctx->daemon_out_list);
	171	daemon->num_queued_msg_ctx--;
	172	printk(KERN_WARNING "%s: Warning: dropping message that is in "
	173	"the out queue of a dying daemon\n", __func__);
	174	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	175	}
	176	hlist_del(&daemon->euid_chain);
f66e883e	177	mutex_unlock(&daemon->mux);
00fcf2cb	178	kzfree(daemon);
f66e883e	179	out:
88b4a07e MH	180	return rc;
	181	}
	182
88b4a07e MH	183	/**
	184	* ecryptfs_process_reponse
	185	* @msg: The ecryptfs message received; the caller should sanity check
f66e883e	186	* msg->data_len and free the memory
f66e883e MH	187	* @seq: The sequence number of the message; must match the sequence
	188	* number for the existing message context waiting for this
	189	* response
	190	*
	191	* Processes a response message after sending an operation request to
	192	* userspace. Some other process is awaiting this response. Before
	193	* sending out its first communications, the other process allocated a
	194	* msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
	195	* response message contains this index so that we can copy over the
	196	* response message into the msg_ctx that the process holds a
	197	* reference to. The other process is going to wake up, check to see
	198	* that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
	199	* proceed to read off and process the response message. Returns zero
	200	* upon delivery to desired context element; non-zero upon delivery
	201	* failure or error.
88b4a07e	202	*
f66e883e	203	* Returns zero on success; non-zero otherwise
88b4a07e	204	*/
2ecaf55d TH	205	int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
2ecaf55d TH	206	struct ecryptfs_message *msg, u32 seq)
88b4a07e	207	{
88b4a07e	208	struct ecryptfs_msg_ctx *msg_ctx;
f66e883e	209	size_t msg_size;
88b4a07e MH	210	int rc;
	211
	212	if (msg->index >= ecryptfs_message_buf_len) {
	213	rc = -EINVAL;
f66e883e MH	214	printk(KERN_ERR "%s: Attempt to reference "
	215	"context buffer at index [%d]; maximum "
	216	"allowable is [%d]\n", __func__, msg->index,
	217	(ecryptfs_message_buf_len - 1));
88b4a07e MH	218	goto out;
	219	}
	220	msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
	221	mutex_lock(&msg_ctx->mux);
88b4a07e MH	222	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
88b4a07e MH	223	rc = -EINVAL;
f66e883e MH	224	printk(KERN_WARNING "%s: Desired context element is not "
f66e883e MH	225	"pending a response\n", __func__);
88b4a07e MH	226	goto unlock;
	227	} else if (msg_ctx->counter != seq) {
	228	rc = -EINVAL;
f66e883e MH	229	printk(KERN_WARNING "%s: Invalid message sequence; "
	230	"expected [%d]; received [%d]\n", __func__,
	231	msg_ctx->counter, seq);
88b4a07e MH	232	goto unlock;
88b4a07e MH	233	}
f66e883e	234	msg_size = (sizeof(*msg) + msg->data_len);
fc8b14d3	235	msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
88b4a07e MH	236	if (!msg_ctx->msg) {
88b4a07e MH	237	rc = -ENOMEM;
88b4a07e MH	238	goto unlock;
88b4a07e MH	239	}
88b4a07e	240	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
88b4a07e	241	wake_up_process(msg_ctx->task);
2ecaf55d	242	rc = 0;
88b4a07e MH	243	unlock:
	244	mutex_unlock(&msg_ctx->mux);
	245	out:
	246	return rc;
	247	}
	248
	249	/**
f66e883e	250	* ecryptfs_send_message_locked
88b4a07e MH	251	* @data: The data to send
	252	* @data_len: The length of data
	253	* @msg_ctx: The message context allocated for the send
f66e883e MH	254	*
	255	* Must be called with ecryptfs_daemon_hash_mux held.
	256	*
	257	* Returns zero on success; non-zero otherwise
88b4a07e	258	*/
f66e883e	259	static int
624ae528 TH	260	ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
624ae528 TH	261	struct ecryptfs_msg_ctx **msg_ctx)
88b4a07e	262	{
f66e883e	263	struct ecryptfs_daemon *daemon;
88b4a07e MH	264	int rc;
88b4a07e MH	265
2ecaf55d	266	rc = ecryptfs_find_daemon_by_euid(&daemon);
1111eae9	267	if (rc) {
88b4a07e	268	rc = -ENOTCONN;
88b4a07e MH	269	goto out;
88b4a07e MH	270	}
88b4a07e MH	271	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	272	rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
	273	if (rc) {
	274	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
f66e883e MH	275	printk(KERN_WARNING "%s: Could not claim a free "
f66e883e MH	276	"context element\n", __func__);
88b4a07e MH	277	goto out;
	278	}
	279	ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
	280	mutex_unlock(&(*msg_ctx)->mux);
	281	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
624ae528 TH	282	rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
624ae528 TH	283	daemon);
f66e883e MH	284	if (rc)
	285	printk(KERN_ERR "%s: Error attempting to send message to "
	286	"userspace daemon; rc = [%d]\n", __func__, rc);
88b4a07e MH	287	out:
	288	return rc;
	289	}
	290
f66e883e MH	291	/**
f66e883e MH	292	* ecryptfs_send_message
f66e883e MH	293	* @data: The data to send
	294	* @data_len: The length of data
	295	* @msg_ctx: The message context allocated for the send
	296	*
	297	* Grabs ecryptfs_daemon_hash_mux.
	298	*
	299	* Returns zero on success; non-zero otherwise
	300	*/
624ae528	301	int ecryptfs_send_message(char *data, int data_len,
f66e883e MH	302	struct ecryptfs_msg_ctx **msg_ctx)
	303	{
	304	int rc;
	305
	306	mutex_lock(&ecryptfs_daemon_hash_mux);
624ae528 TH	307	rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
624ae528 TH	308	msg_ctx);
f66e883e MH	309	mutex_unlock(&ecryptfs_daemon_hash_mux);
	310	return rc;
	311	}
	312
88b4a07e MH	313	/**
	314	* ecryptfs_wait_for_response
	315	* @msg_ctx: The context that was assigned when sending a message
	316	* @msg: The incoming message from userspace; not set if rc != 0
	317	*
	318	* Sleeps until awaken by ecryptfs_receive_message or until the amount
	319	* of time exceeds ecryptfs_message_wait_timeout. If zero is
	320	* returned, msg will point to a valid message from userspace; a
	321	* non-zero value is returned upon failure to receive a message or an
f66e883e	322	* error occurs. Callee must free @msg on success.
88b4a07e MH	323	*/
	324	int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
	325	struct ecryptfs_message **msg)
	326	{
	327	signed long timeout = ecryptfs_message_wait_timeout * HZ;
	328	int rc = 0;
	329
	330	sleep:
	331	timeout = schedule_timeout_interruptible(timeout);
	332	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	333	mutex_lock(&msg_ctx->mux);
	334	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
	335	if (timeout) {
	336	mutex_unlock(&msg_ctx->mux);
	337	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	338	goto sleep;
	339	}
	340	rc = -ENOMSG;
	341	} else {
	342	*msg = msg_ctx->msg;
	343	msg_ctx->msg = NULL;
	344	}
	345	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	346	mutex_unlock(&msg_ctx->mux);
	347	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	348	return rc;
	349	}
	350
7371a382	351	int __init ecryptfs_init_messaging(void)
88b4a07e MH	352	{
	353	int i;
	354	int rc = 0;
	355
	356	if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
	357	ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
f66e883e MH	358	printk(KERN_WARNING "%s: Specified number of users is "
	359	"too large, defaulting to [%d] users\n", __func__,
	360	ecryptfs_number_of_users);
88b4a07e	361	}
f66e883e MH	362	mutex_init(&ecryptfs_daemon_hash_mux);
f66e883e MH	363	mutex_lock(&ecryptfs_daemon_hash_mux);
a6f80fb7 AO	364	ecryptfs_hash_bits = 1;
	365	while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
	366	ecryptfs_hash_bits++;
f66e883e	367	ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
a6f80fb7 AO	368	* (1 << ecryptfs_hash_bits)),
a6f80fb7 AO	369	GFP_KERNEL);
f66e883e	370	if (!ecryptfs_daemon_hash) {
88b4a07e	371	rc = -ENOMEM;
f66e883e	372	mutex_unlock(&ecryptfs_daemon_hash_mux);
88b4a07e MH	373	goto out;
88b4a07e MH	374	}
a6f80fb7	375	for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
f66e883e MH	376	INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
f66e883e MH	377	mutex_unlock(&ecryptfs_daemon_hash_mux);
88b4a07e	378	ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
f66e883e MH	379	* ecryptfs_message_buf_len),
f66e883e MH	380	GFP_KERNEL);
88b4a07e MH	381	if (!ecryptfs_msg_ctx_arr) {
88b4a07e MH	382	rc = -ENOMEM;
88b4a07e MH	383	goto out;
	384	}
	385	mutex_init(&ecryptfs_msg_ctx_lists_mux);
	386	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	387	ecryptfs_msg_counter = 0;
	388	for (i = 0; i < ecryptfs_message_buf_len; i++) {
	389	INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
f66e883e	390	INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
88b4a07e MH	391	mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
	392	mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
	393	ecryptfs_msg_ctx_arr[i].index = i;
	394	ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
	395	ecryptfs_msg_ctx_arr[i].counter = 0;
	396	ecryptfs_msg_ctx_arr[i].task = NULL;
	397	ecryptfs_msg_ctx_arr[i].msg = NULL;
	398	list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
	399	&ecryptfs_msg_ctx_free_list);
	400	mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
	401	}
	402	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
624ae528 TH	403	rc = ecryptfs_init_ecryptfs_miscdev();
	404	if (rc)
	405	ecryptfs_release_messaging();
88b4a07e MH	406	out:
	407	return rc;
	408	}
	409
624ae528	410	void ecryptfs_release_messaging(void)
88b4a07e MH	411	{
	412	if (ecryptfs_msg_ctx_arr) {
	413	int i;
	414
	415	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	416	for (i = 0; i < ecryptfs_message_buf_len; i++) {
	417	mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
3db593e8	418	kfree(ecryptfs_msg_ctx_arr[i].msg);
88b4a07e MH	419	mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
	420	}
	421	kfree(ecryptfs_msg_ctx_arr);
	422	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	423	}
f66e883e	424	if (ecryptfs_daemon_hash) {
f66e883e	425	struct ecryptfs_daemon *daemon;
db86be3a	426	struct hlist_node *n;
88b4a07e MH	427	int i;
88b4a07e MH	428
f66e883e	429	mutex_lock(&ecryptfs_daemon_hash_mux);
a6f80fb7	430	for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
f66e883e MH	431	int rc;
f66e883e MH	432
db86be3a DC	433	hlist_for_each_entry_safe(daemon, n,
	434	&ecryptfs_daemon_hash[i],
	435	euid_chain) {
f66e883e MH	436	rc = ecryptfs_exorcise_daemon(daemon);
	437	if (rc)
	438	printk(KERN_ERR "%s: Error whilst "
	439	"attempting to destroy daemon; "
	440	"rc = [%d]. Dazed and confused, "
	441	"but trying to continue.\n",
	442	__func__, rc);
88b4a07e MH	443	}
88b4a07e MH	444	}
f66e883e MH	445	kfree(ecryptfs_daemon_hash);
f66e883e MH	446	mutex_unlock(&ecryptfs_daemon_hash_mux);
88b4a07e	447	}
624ae528	448	ecryptfs_destroy_ecryptfs_miscdev();
88b4a07e MH	449	return;
88b4a07e MH	450	}