2 * eCryptfs: Linux filesystem encryption layer
4 * Copyright (C) 2004-2008 International Business Machines Corp.
5 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
6 * Tyler Hicks <tyhicks@ou.edu>
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.
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.
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
22 #include <linux/sched.h>
23 #include <linux/user_namespace.h>
24 #include <linux/nsproxy.h>
25 #include "ecryptfs_kernel.h"
27 static LIST_HEAD(ecryptfs_msg_ctx_free_list);
28 static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
29 static struct mutex ecryptfs_msg_ctx_lists_mux;
31 static struct hlist_head *ecryptfs_daemon_hash;
32 struct mutex ecryptfs_daemon_hash_mux;
33 static int ecryptfs_hash_buckets;
34 #define ecryptfs_uid_hash(uid) \
35 hash_long((unsigned long)uid, ecryptfs_hash_buckets)
37 static u32 ecryptfs_msg_counter;
38 static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
41 * ecryptfs_acquire_free_msg_ctx
42 * @msg_ctx: The context that was acquired from the free list
44 * Acquires a context element from the free list and locks the mutex
45 * on the context. Sets the msg_ctx task to current. Returns zero on
46 * success; non-zero on error or upon failure to acquire a free
47 * context element. Must be called with ecryptfs_msg_ctx_lists_mux
50 static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
55 if (list_empty(&ecryptfs_msg_ctx_free_list)) {
56 printk(KERN_WARNING "%s: The eCryptfs free "
57 "context list is empty. It may be helpful to "
58 "specify the ecryptfs_message_buf_len "
59 "parameter to be greater than the current "
60 "value of [%d]\n", __func__, ecryptfs_message_buf_len);
64 list_for_each(p, &ecryptfs_msg_ctx_free_list) {
65 *msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
66 if (mutex_trylock(&(*msg_ctx)->mux)) {
67 (*msg_ctx)->task = current;
78 * ecryptfs_msg_ctx_free_to_alloc
79 * @msg_ctx: The context to move from the free list to the alloc list
81 * Must be called with ecryptfs_msg_ctx_lists_mux held.
83 static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
85 list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
86 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
87 msg_ctx->counter = ++ecryptfs_msg_counter;
91 * ecryptfs_msg_ctx_alloc_to_free
92 * @msg_ctx: The context to move from the alloc list to the free list
94 * Must be called with ecryptfs_msg_ctx_lists_mux held.
96 void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
98 list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
102 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
106 * ecryptfs_find_daemon_by_euid
107 * @euid: The effective user id which maps to the desired daemon id
108 * @user_ns: The namespace in which @euid applies
109 * @daemon: If return value is zero, points to the desired daemon pointer
111 * Must be called with ecryptfs_daemon_hash_mux held.
113 * Search the hash list for the given user id.
115 * Returns zero if the user id exists in the list; non-zero otherwise.
117 int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon, uid_t euid,
118 struct user_namespace *user_ns)
120 struct hlist_node *elem;
123 hlist_for_each_entry(*daemon, elem,
124 &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)],
126 if ((*daemon)->euid == euid && (*daemon)->user_ns == user_ns) {
137 * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
138 * @daemon: Pointer to set to newly allocated daemon struct
139 * @euid: Effective user id for the daemon
140 * @user_ns: The namespace in which @euid applies
141 * @pid: Process id for the daemon
143 * Must be called ceremoniously while in possession of
144 * ecryptfs_sacred_daemon_hash_mux
146 * Returns zero on success; non-zero otherwise
149 ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, uid_t euid,
150 struct user_namespace *user_ns, struct pid *pid)
154 (*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
157 printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
158 "GFP_KERNEL memory\n", __func__, sizeof(**daemon));
161 (*daemon)->euid = euid;
162 (*daemon)->user_ns = get_user_ns(user_ns);
163 (*daemon)->pid = get_pid(pid);
164 (*daemon)->task = current;
165 mutex_init(&(*daemon)->mux);
166 INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
167 init_waitqueue_head(&(*daemon)->wait);
168 (*daemon)->num_queued_msg_ctx = 0;
169 hlist_add_head(&(*daemon)->euid_chain,
170 &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)]);
176 * ecryptfs_exorcise_daemon - Destroy the daemon struct
178 * Must be called ceremoniously while in possession of
179 * ecryptfs_daemon_hash_mux and the daemon's own mux.
181 int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
183 struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp;
186 mutex_lock(&daemon->mux);
187 if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
188 || (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
190 printk(KERN_WARNING "%s: Attempt to destroy daemon with pid "
191 "[0x%p], but it is in the midst of a read or a poll\n",
192 __func__, daemon->pid);
193 mutex_unlock(&daemon->mux);
196 list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
197 &daemon->msg_ctx_out_queue, daemon_out_list) {
198 list_del(&msg_ctx->daemon_out_list);
199 daemon->num_queued_msg_ctx--;
200 printk(KERN_WARNING "%s: Warning: dropping message that is in "
201 "the out queue of a dying daemon\n", __func__);
202 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
204 hlist_del(&daemon->euid_chain);
206 wake_up_process(daemon->task);
208 put_pid(daemon->pid);
210 put_user_ns(daemon->user_ns);
211 mutex_unlock(&daemon->mux);
218 * ecryptfs_process_quit
219 * @euid: The user ID owner of the message
220 * @user_ns: The namespace in which @euid applies
221 * @pid: The process ID for the userspace program that sent the
224 * Deletes the corresponding daemon for the given euid and pid, if
225 * it is the registered that is requesting the deletion. Returns zero
226 * after deleting the desired daemon; non-zero otherwise.
228 int ecryptfs_process_quit(uid_t euid, struct user_namespace *user_ns,
231 struct ecryptfs_daemon *daemon;
234 mutex_lock(&ecryptfs_daemon_hash_mux);
235 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, user_ns);
238 printk(KERN_ERR "Received request from user [%d] to "
239 "unregister unrecognized daemon [0x%p]\n", euid, pid);
242 rc = ecryptfs_exorcise_daemon(daemon);
244 mutex_unlock(&ecryptfs_daemon_hash_mux);
249 * ecryptfs_process_reponse
250 * @msg: The ecryptfs message received; the caller should sanity check
251 * msg->data_len and free the memory
252 * @pid: The process ID of the userspace application that sent the
254 * @seq: The sequence number of the message; must match the sequence
255 * number for the existing message context waiting for this
258 * Processes a response message after sending an operation request to
259 * userspace. Some other process is awaiting this response. Before
260 * sending out its first communications, the other process allocated a
261 * msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
262 * response message contains this index so that we can copy over the
263 * response message into the msg_ctx that the process holds a
264 * reference to. The other process is going to wake up, check to see
265 * that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
266 * proceed to read off and process the response message. Returns zero
267 * upon delivery to desired context element; non-zero upon delivery
270 * Returns zero on success; non-zero otherwise
272 int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
273 struct user_namespace *user_ns, struct pid *pid,
276 struct ecryptfs_daemon *daemon;
277 struct ecryptfs_msg_ctx *msg_ctx;
279 struct nsproxy *nsproxy;
280 struct user_namespace *tsk_user_ns;
284 if (msg->index >= ecryptfs_message_buf_len) {
286 printk(KERN_ERR "%s: Attempt to reference "
287 "context buffer at index [%d]; maximum "
288 "allowable is [%d]\n", __func__, msg->index,
289 (ecryptfs_message_buf_len - 1));
292 msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
293 mutex_lock(&msg_ctx->mux);
294 mutex_lock(&ecryptfs_daemon_hash_mux);
296 nsproxy = task_nsproxy(msg_ctx->task);
297 if (nsproxy == NULL) {
299 printk(KERN_ERR "%s: Receiving process is a zombie. Dropping "
300 "message.\n", __func__);
302 mutex_unlock(&ecryptfs_daemon_hash_mux);
305 tsk_user_ns = __task_cred(msg_ctx->task)->user->user_ns;
306 ctx_euid = task_euid(msg_ctx->task);
307 rc = ecryptfs_find_daemon_by_euid(&daemon, ctx_euid, tsk_user_ns);
309 mutex_unlock(&ecryptfs_daemon_hash_mux);
312 printk(KERN_WARNING "%s: User [%d] received a "
313 "message response from process [0x%p] but does "
314 "not have a registered daemon\n", __func__,
318 if (ctx_euid != euid) {
320 printk(KERN_WARNING "%s: Received message from user "
321 "[%d]; expected message from user [%d]\n", __func__,
325 if (tsk_user_ns != user_ns) {
327 printk(KERN_WARNING "%s: Received message from user_ns "
328 "[0x%p]; expected message from user_ns [0x%p]\n",
329 __func__, user_ns, tsk_user_ns);
332 if (daemon->pid != pid) {
334 printk(KERN_ERR "%s: User [%d] sent a message response "
335 "from an unrecognized process [0x%p]\n",
336 __func__, ctx_euid, pid);
339 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
341 printk(KERN_WARNING "%s: Desired context element is not "
342 "pending a response\n", __func__);
344 } else if (msg_ctx->counter != seq) {
346 printk(KERN_WARNING "%s: Invalid message sequence; "
347 "expected [%d]; received [%d]\n", __func__,
348 msg_ctx->counter, seq);
351 msg_size = (sizeof(*msg) + msg->data_len);
352 msg_ctx->msg = kmalloc(msg_size, GFP_KERNEL);
355 printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
356 "GFP_KERNEL memory\n", __func__, msg_size);
359 memcpy(msg_ctx->msg, msg, msg_size);
360 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
363 wake_up_process(msg_ctx->task);
365 mutex_unlock(&msg_ctx->mux);
371 * ecryptfs_send_message_locked
372 * @data: The data to send
373 * @data_len: The length of data
374 * @msg_ctx: The message context allocated for the send
376 * Must be called with ecryptfs_daemon_hash_mux held.
378 * Returns zero on success; non-zero otherwise
381 ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
382 struct ecryptfs_msg_ctx **msg_ctx)
384 struct ecryptfs_daemon *daemon;
385 uid_t euid = current_euid();
388 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
391 printk(KERN_ERR "%s: User [%d] does not have a daemon "
392 "registered\n", __func__, euid);
395 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
396 rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
398 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
399 printk(KERN_WARNING "%s: Could not claim a free "
400 "context element\n", __func__);
403 ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
404 mutex_unlock(&(*msg_ctx)->mux);
405 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
406 rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
409 printk(KERN_ERR "%s: Error attempting to send message to "
410 "userspace daemon; rc = [%d]\n", __func__, rc);
416 * ecryptfs_send_message
417 * @data: The data to send
418 * @data_len: The length of data
419 * @msg_ctx: The message context allocated for the send
421 * Grabs ecryptfs_daemon_hash_mux.
423 * Returns zero on success; non-zero otherwise
425 int ecryptfs_send_message(char *data, int data_len,
426 struct ecryptfs_msg_ctx **msg_ctx)
430 mutex_lock(&ecryptfs_daemon_hash_mux);
431 rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
433 mutex_unlock(&ecryptfs_daemon_hash_mux);
438 * ecryptfs_wait_for_response
439 * @msg_ctx: The context that was assigned when sending a message
440 * @msg: The incoming message from userspace; not set if rc != 0
442 * Sleeps until awaken by ecryptfs_receive_message or until the amount
443 * of time exceeds ecryptfs_message_wait_timeout. If zero is
444 * returned, msg will point to a valid message from userspace; a
445 * non-zero value is returned upon failure to receive a message or an
446 * error occurs. Callee must free @msg on success.
448 int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
449 struct ecryptfs_message **msg)
451 signed long timeout = ecryptfs_message_wait_timeout * HZ;
455 timeout = schedule_timeout_interruptible(timeout);
456 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
457 mutex_lock(&msg_ctx->mux);
458 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
460 mutex_unlock(&msg_ctx->mux);
461 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
469 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
470 mutex_unlock(&msg_ctx->mux);
471 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
475 int ecryptfs_init_messaging(void)
480 if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
481 ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
482 printk(KERN_WARNING "%s: Specified number of users is "
483 "too large, defaulting to [%d] users\n", __func__,
484 ecryptfs_number_of_users);
486 mutex_init(&ecryptfs_daemon_hash_mux);
487 mutex_lock(&ecryptfs_daemon_hash_mux);
488 ecryptfs_hash_buckets = 1;
489 while (ecryptfs_number_of_users >> ecryptfs_hash_buckets)
490 ecryptfs_hash_buckets++;
491 ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
492 * ecryptfs_hash_buckets), GFP_KERNEL);
493 if (!ecryptfs_daemon_hash) {
495 printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
496 mutex_unlock(&ecryptfs_daemon_hash_mux);
499 for (i = 0; i < ecryptfs_hash_buckets; i++)
500 INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
501 mutex_unlock(&ecryptfs_daemon_hash_mux);
502 ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
503 * ecryptfs_message_buf_len),
505 if (!ecryptfs_msg_ctx_arr) {
507 printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
510 mutex_init(&ecryptfs_msg_ctx_lists_mux);
511 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
512 ecryptfs_msg_counter = 0;
513 for (i = 0; i < ecryptfs_message_buf_len; i++) {
514 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
515 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
516 mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
517 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
518 ecryptfs_msg_ctx_arr[i].index = i;
519 ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
520 ecryptfs_msg_ctx_arr[i].counter = 0;
521 ecryptfs_msg_ctx_arr[i].task = NULL;
522 ecryptfs_msg_ctx_arr[i].msg = NULL;
523 list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
524 &ecryptfs_msg_ctx_free_list);
525 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
527 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
528 rc = ecryptfs_init_ecryptfs_miscdev();
530 ecryptfs_release_messaging();
535 void ecryptfs_release_messaging(void)
537 if (ecryptfs_msg_ctx_arr) {
540 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
541 for (i = 0; i < ecryptfs_message_buf_len; i++) {
542 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
543 if (ecryptfs_msg_ctx_arr[i].msg)
544 kfree(ecryptfs_msg_ctx_arr[i].msg);
545 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
547 kfree(ecryptfs_msg_ctx_arr);
548 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
550 if (ecryptfs_daemon_hash) {
551 struct hlist_node *elem;
552 struct ecryptfs_daemon *daemon;
555 mutex_lock(&ecryptfs_daemon_hash_mux);
556 for (i = 0; i < ecryptfs_hash_buckets; i++) {
559 hlist_for_each_entry(daemon, elem,
560 &ecryptfs_daemon_hash[i],
562 rc = ecryptfs_exorcise_daemon(daemon);
564 printk(KERN_ERR "%s: Error whilst "
565 "attempting to destroy daemon; "
566 "rc = [%d]. Dazed and confused, "
567 "but trying to continue.\n",
571 kfree(ecryptfs_daemon_hash);
572 mutex_unlock(&ecryptfs_daemon_hash_mux);
574 ecryptfs_destroy_ecryptfs_miscdev();