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1/**
2 * eCryptfs: Linux filesystem encryption layer
3 *
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>
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 */
22#include <linux/sched.h>
23#include <linux/slab.h>
24#include <linux/user_namespace.h>
25#include <linux/nsproxy.h>
26#include "ecryptfs_kernel.h"
27
28static LIST_HEAD(ecryptfs_msg_ctx_free_list);
29static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
30static struct mutex ecryptfs_msg_ctx_lists_mux;
31
32static struct hlist_head *ecryptfs_daemon_hash;
33struct mutex ecryptfs_daemon_hash_mux;
34static int ecryptfs_hash_bits;
35#define ecryptfs_uid_hash(uid) \
36 hash_long((unsigned long)uid, ecryptfs_hash_bits)
37
38static u32 ecryptfs_msg_counter;
39static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
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
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.
50 */
51static 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)) {
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);
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;
74out:
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 *
82 * Must be called with ecryptfs_msg_ctx_lists_mux held.
83 */
84static 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 *
95 * Must be called with ecryptfs_msg_ctx_lists_mux held.
96 */
97void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
98{
99 list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
100 if (msg_ctx->msg)
101 kfree(msg_ctx->msg);
102 msg_ctx->msg = NULL;
103 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
104}
105
106/**
107 * ecryptfs_find_daemon_by_euid
108 * @euid: The effective user id which maps to the desired daemon id
109 * @user_ns: The namespace in which @euid applies
110 * @daemon: If return value is zero, points to the desired daemon pointer
111 *
112 * Must be called with ecryptfs_daemon_hash_mux held.
113 *
114 * Search the hash list for the given user id.
115 *
116 * Returns zero if the user id exists in the list; non-zero otherwise.
117 */
118int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon, uid_t euid,
119 struct user_namespace *user_ns)
120{
121 struct hlist_node *elem;
122 int rc;
123
124 hlist_for_each_entry(*daemon, elem,
125 &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)],
126 euid_chain) {
127 if ((*daemon)->euid == euid && (*daemon)->user_ns == user_ns) {
128 rc = 0;
129 goto out;
130 }
131 }
132 rc = -EINVAL;
133out:
134 return rc;
135}
136
137/**
138 * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
139 * @daemon: Pointer to set to newly allocated daemon struct
140 * @euid: Effective user id for the daemon
141 * @user_ns: The namespace in which @euid applies
142 * @pid: Process id for the daemon
143 *
144 * Must be called ceremoniously while in possession of
145 * ecryptfs_sacred_daemon_hash_mux
146 *
147 * Returns zero on success; non-zero otherwise
148 */
149int
150ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, uid_t euid,
151 struct user_namespace *user_ns, struct pid *pid)
152{
153 int rc = 0;
154
155 (*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
156 if (!(*daemon)) {
157 rc = -ENOMEM;
158 printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
159 "GFP_KERNEL memory\n", __func__, sizeof(**daemon));
160 goto out;
161 }
162 (*daemon)->euid = euid;
163 (*daemon)->user_ns = get_user_ns(user_ns);
164 (*daemon)->pid = get_pid(pid);
165 (*daemon)->task = current;
166 mutex_init(&(*daemon)->mux);
167 INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
168 init_waitqueue_head(&(*daemon)->wait);
169 (*daemon)->num_queued_msg_ctx = 0;
170 hlist_add_head(&(*daemon)->euid_chain,
171 &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)]);
172out:
173 return rc;
174}
175
176/**
177 * ecryptfs_exorcise_daemon - Destroy the daemon struct
178 *
179 * Must be called ceremoniously while in possession of
180 * ecryptfs_daemon_hash_mux and the daemon's own mux.
181 */
182int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
183{
184 struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp;
185 int rc = 0;
186
187 mutex_lock(&daemon->mux);
188 if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
189 || (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
190 rc = -EBUSY;
191 printk(KERN_WARNING "%s: Attempt to destroy daemon with pid "
192 "[0x%p], but it is in the midst of a read or a poll\n",
193 __func__, daemon->pid);
194 mutex_unlock(&daemon->mux);
195 goto out;
196 }
197 list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
198 &daemon->msg_ctx_out_queue, daemon_out_list) {
199 list_del(&msg_ctx->daemon_out_list);
200 daemon->num_queued_msg_ctx--;
201 printk(KERN_WARNING "%s: Warning: dropping message that is in "
202 "the out queue of a dying daemon\n", __func__);
203 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
204 }
205 hlist_del(&daemon->euid_chain);
206 if (daemon->task)
207 wake_up_process(daemon->task);
208 if (daemon->pid)
209 put_pid(daemon->pid);
210 if (daemon->user_ns)
211 put_user_ns(daemon->user_ns);
212 mutex_unlock(&daemon->mux);
213 kzfree(daemon);
214out:
215 return rc;
216}
217
218/**
219 * ecryptfs_process_quit
220 * @euid: The user ID owner of the message
221 * @user_ns: The namespace in which @euid applies
222 * @pid: The process ID for the userspace program that sent the
223 * message
224 *
225 * Deletes the corresponding daemon for the given euid and pid, if
226 * it is the registered that is requesting the deletion. Returns zero
227 * after deleting the desired daemon; non-zero otherwise.
228 */
229int ecryptfs_process_quit(uid_t euid, struct user_namespace *user_ns,
230 struct pid *pid)
231{
232 struct ecryptfs_daemon *daemon;
233 int rc;
234
235 mutex_lock(&ecryptfs_daemon_hash_mux);
236 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, user_ns);
237 if (rc || !daemon) {
238 rc = -EINVAL;
239 printk(KERN_ERR "Received request from user [%d] to "
240 "unregister unrecognized daemon [0x%p]\n", euid, pid);
241 goto out_unlock;
242 }
243 rc = ecryptfs_exorcise_daemon(daemon);
244out_unlock:
245 mutex_unlock(&ecryptfs_daemon_hash_mux);
246 return rc;
247}
248
249/**
250 * ecryptfs_process_reponse
251 * @msg: The ecryptfs message received; the caller should sanity check
252 * msg->data_len and free the memory
253 * @pid: The process ID of the userspace application that sent the
254 * message
255 * @seq: The sequence number of the message; must match the sequence
256 * number for the existing message context waiting for this
257 * response
258 *
259 * Processes a response message after sending an operation request to
260 * userspace. Some other process is awaiting this response. Before
261 * sending out its first communications, the other process allocated a
262 * msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
263 * response message contains this index so that we can copy over the
264 * response message into the msg_ctx that the process holds a
265 * reference to. The other process is going to wake up, check to see
266 * that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
267 * proceed to read off and process the response message. Returns zero
268 * upon delivery to desired context element; non-zero upon delivery
269 * failure or error.
270 *
271 * Returns zero on success; non-zero otherwise
272 */
273int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
274 struct user_namespace *user_ns, struct pid *pid,
275 u32 seq)
276{
277 struct ecryptfs_daemon *uninitialized_var(daemon);
278 struct ecryptfs_msg_ctx *msg_ctx;
279 size_t msg_size;
280 struct nsproxy *nsproxy;
281 struct user_namespace *tsk_user_ns;
282 uid_t ctx_euid;
283 int rc;
284
285 if (msg->index >= ecryptfs_message_buf_len) {
286 rc = -EINVAL;
287 printk(KERN_ERR "%s: Attempt to reference "
288 "context buffer at index [%d]; maximum "
289 "allowable is [%d]\n", __func__, msg->index,
290 (ecryptfs_message_buf_len - 1));
291 goto out;
292 }
293 msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
294 mutex_lock(&msg_ctx->mux);
295 mutex_lock(&ecryptfs_daemon_hash_mux);
296 rcu_read_lock();
297 nsproxy = task_nsproxy(msg_ctx->task);
298 if (nsproxy == NULL) {
299 rc = -EBADMSG;
300 printk(KERN_ERR "%s: Receiving process is a zombie. Dropping "
301 "message.\n", __func__);
302 rcu_read_unlock();
303 mutex_unlock(&ecryptfs_daemon_hash_mux);
304 goto wake_up;
305 }
306 tsk_user_ns = __task_cred(msg_ctx->task)->user->user_ns;
307 ctx_euid = task_euid(msg_ctx->task);
308 rc = ecryptfs_find_daemon_by_euid(&daemon, ctx_euid, tsk_user_ns);
309 rcu_read_unlock();
310 mutex_unlock(&ecryptfs_daemon_hash_mux);
311 if (rc) {
312 rc = -EBADMSG;
313 printk(KERN_WARNING "%s: User [%d] received a "
314 "message response from process [0x%p] but does "
315 "not have a registered daemon\n", __func__,
316 ctx_euid, pid);
317 goto wake_up;
318 }
319 if (ctx_euid != euid) {
320 rc = -EBADMSG;
321 printk(KERN_WARNING "%s: Received message from user "
322 "[%d]; expected message from user [%d]\n", __func__,
323 euid, ctx_euid);
324 goto unlock;
325 }
326 if (tsk_user_ns != user_ns) {
327 rc = -EBADMSG;
328 printk(KERN_WARNING "%s: Received message from user_ns "
329 "[0x%p]; expected message from user_ns [0x%p]\n",
330 __func__, user_ns, tsk_user_ns);
331 goto unlock;
332 }
333 if (daemon->pid != pid) {
334 rc = -EBADMSG;
335 printk(KERN_ERR "%s: User [%d] sent a message response "
336 "from an unrecognized process [0x%p]\n",
337 __func__, ctx_euid, pid);
338 goto unlock;
339 }
340 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
341 rc = -EINVAL;
342 printk(KERN_WARNING "%s: Desired context element is not "
343 "pending a response\n", __func__);
344 goto unlock;
345 } else if (msg_ctx->counter != seq) {
346 rc = -EINVAL;
347 printk(KERN_WARNING "%s: Invalid message sequence; "
348 "expected [%d]; received [%d]\n", __func__,
349 msg_ctx->counter, seq);
350 goto unlock;
351 }
352 msg_size = (sizeof(*msg) + msg->data_len);
353 msg_ctx->msg = kmalloc(msg_size, GFP_KERNEL);
354 if (!msg_ctx->msg) {
355 rc = -ENOMEM;
356 printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
357 "GFP_KERNEL memory\n", __func__, msg_size);
358 goto unlock;
359 }
360 memcpy(msg_ctx->msg, msg, msg_size);
361 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
362 rc = 0;
363wake_up:
364 wake_up_process(msg_ctx->task);
365unlock:
366 mutex_unlock(&msg_ctx->mux);
367out:
368 return rc;
369}
370
371/**
372 * ecryptfs_send_message_locked
373 * @data: The data to send
374 * @data_len: The length of data
375 * @msg_ctx: The message context allocated for the send
376 *
377 * Must be called with ecryptfs_daemon_hash_mux held.
378 *
379 * Returns zero on success; non-zero otherwise
380 */
381static int
382ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
383 struct ecryptfs_msg_ctx **msg_ctx)
384{
385 struct ecryptfs_daemon *daemon;
386 uid_t euid = current_euid();
387 int rc;
388
389 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
390 if (rc || !daemon) {
391 rc = -ENOTCONN;
392 printk(KERN_ERR "%s: User [%d] does not have a daemon "
393 "registered\n", __func__, euid);
394 goto out;
395 }
396 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
397 rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
398 if (rc) {
399 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
400 printk(KERN_WARNING "%s: Could not claim a free "
401 "context element\n", __func__);
402 goto out;
403 }
404 ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
405 mutex_unlock(&(*msg_ctx)->mux);
406 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
407 rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
408 daemon);
409 if (rc)
410 printk(KERN_ERR "%s: Error attempting to send message to "
411 "userspace daemon; rc = [%d]\n", __func__, rc);
412out:
413 return rc;
414}
415
416/**
417 * ecryptfs_send_message
418 * @data: The data to send
419 * @data_len: The length of data
420 * @msg_ctx: The message context allocated for the send
421 *
422 * Grabs ecryptfs_daemon_hash_mux.
423 *
424 * Returns zero on success; non-zero otherwise
425 */
426int ecryptfs_send_message(char *data, int data_len,
427 struct ecryptfs_msg_ctx **msg_ctx)
428{
429 int rc;
430
431 mutex_lock(&ecryptfs_daemon_hash_mux);
432 rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
433 msg_ctx);
434 mutex_unlock(&ecryptfs_daemon_hash_mux);
435 return rc;
436}
437
438/**
439 * ecryptfs_wait_for_response
440 * @msg_ctx: The context that was assigned when sending a message
441 * @msg: The incoming message from userspace; not set if rc != 0
442 *
443 * Sleeps until awaken by ecryptfs_receive_message or until the amount
444 * of time exceeds ecryptfs_message_wait_timeout. If zero is
445 * returned, msg will point to a valid message from userspace; a
446 * non-zero value is returned upon failure to receive a message or an
447 * error occurs. Callee must free @msg on success.
448 */
449int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
450 struct ecryptfs_message **msg)
451{
452 signed long timeout = ecryptfs_message_wait_timeout * HZ;
453 int rc = 0;
454
455sleep:
456 timeout = schedule_timeout_interruptible(timeout);
457 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
458 mutex_lock(&msg_ctx->mux);
459 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
460 if (timeout) {
461 mutex_unlock(&msg_ctx->mux);
462 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
463 goto sleep;
464 }
465 rc = -ENOMSG;
466 } else {
467 *msg = msg_ctx->msg;
468 msg_ctx->msg = NULL;
469 }
470 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
471 mutex_unlock(&msg_ctx->mux);
472 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
473 return rc;
474}
475
476int __init ecryptfs_init_messaging(void)
477{
478 int i;
479 int rc = 0;
480
481 if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
482 ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
483 printk(KERN_WARNING "%s: Specified number of users is "
484 "too large, defaulting to [%d] users\n", __func__,
485 ecryptfs_number_of_users);
486 }
487 mutex_init(&ecryptfs_daemon_hash_mux);
488 mutex_lock(&ecryptfs_daemon_hash_mux);
489 ecryptfs_hash_bits = 1;
490 while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
491 ecryptfs_hash_bits++;
492 ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
493 * (1 << ecryptfs_hash_bits)),
494 GFP_KERNEL);
495 if (!ecryptfs_daemon_hash) {
496 rc = -ENOMEM;
497 printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
498 mutex_unlock(&ecryptfs_daemon_hash_mux);
499 goto out;
500 }
501 for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
502 INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
503 mutex_unlock(&ecryptfs_daemon_hash_mux);
504 ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
505 * ecryptfs_message_buf_len),
506 GFP_KERNEL);
507 if (!ecryptfs_msg_ctx_arr) {
508 rc = -ENOMEM;
509 printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
510 goto out;
511 }
512 mutex_init(&ecryptfs_msg_ctx_lists_mux);
513 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
514 ecryptfs_msg_counter = 0;
515 for (i = 0; i < ecryptfs_message_buf_len; i++) {
516 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
517 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
518 mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
519 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
520 ecryptfs_msg_ctx_arr[i].index = i;
521 ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
522 ecryptfs_msg_ctx_arr[i].counter = 0;
523 ecryptfs_msg_ctx_arr[i].task = NULL;
524 ecryptfs_msg_ctx_arr[i].msg = NULL;
525 list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
526 &ecryptfs_msg_ctx_free_list);
527 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
528 }
529 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
530 rc = ecryptfs_init_ecryptfs_miscdev();
531 if (rc)
532 ecryptfs_release_messaging();
533out:
534 return rc;
535}
536
537void ecryptfs_release_messaging(void)
538{
539 if (ecryptfs_msg_ctx_arr) {
540 int i;
541
542 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
543 for (i = 0; i < ecryptfs_message_buf_len; i++) {
544 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
545 if (ecryptfs_msg_ctx_arr[i].msg)
546 kfree(ecryptfs_msg_ctx_arr[i].msg);
547 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
548 }
549 kfree(ecryptfs_msg_ctx_arr);
550 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
551 }
552 if (ecryptfs_daemon_hash) {
553 struct hlist_node *elem;
554 struct ecryptfs_daemon *daemon;
555 int i;
556
557 mutex_lock(&ecryptfs_daemon_hash_mux);
558 for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
559 int rc;
560
561 hlist_for_each_entry(daemon, elem,
562 &ecryptfs_daemon_hash[i],
563 euid_chain) {
564 rc = ecryptfs_exorcise_daemon(daemon);
565 if (rc)
566 printk(KERN_ERR "%s: Error whilst "
567 "attempting to destroy daemon; "
568 "rc = [%d]. Dazed and confused, "
569 "but trying to continue.\n",
570 __func__, rc);
571 }
572 }
573 kfree(ecryptfs_daemon_hash);
574 mutex_unlock(&ecryptfs_daemon_hash_mux);
575 }
576 ecryptfs_destroy_ecryptfs_miscdev();
577 return;
578}
1// SPDX-License-Identifier: GPL-2.0-only
2/**
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 2004-2008 International Business Machines Corp.
6 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
7 * Tyler Hicks <tyhicks@ou.edu>
8 */
9#include <linux/sched.h>
10#include <linux/slab.h>
11#include <linux/user_namespace.h>
12#include <linux/nsproxy.h>
13#include "ecryptfs_kernel.h"
14
15static LIST_HEAD(ecryptfs_msg_ctx_free_list);
16static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
17static struct mutex ecryptfs_msg_ctx_lists_mux;
18
19static struct hlist_head *ecryptfs_daemon_hash;
20struct mutex ecryptfs_daemon_hash_mux;
21static int ecryptfs_hash_bits;
22#define ecryptfs_current_euid_hash(uid) \
23 hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)
24
25static u32 ecryptfs_msg_counter;
26static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
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
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.
37 */
38static 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)) {
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);
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;
61out:
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 *
69 * Must be called with ecryptfs_msg_ctx_lists_mux held.
70 */
71static 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 *
82 * Must be called with ecryptfs_msg_ctx_lists_mux held.
83 */
84void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
85{
86 list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
87 kfree(msg_ctx->msg);
88 msg_ctx->msg = NULL;
89 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
90}
91
92/**
93 * ecryptfs_find_daemon_by_euid
94 * @daemon: If return value is zero, points to the desired daemon pointer
95 *
96 * Must be called with ecryptfs_daemon_hash_mux held.
97 *
98 * Search the hash list for the current effective user id.
99 *
100 * Returns zero if the user id exists in the list; non-zero otherwise.
101 */
102int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
103{
104 int rc;
105
106 hlist_for_each_entry(*daemon,
107 &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
108 euid_chain) {
109 if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
110 rc = 0;
111 goto out;
112 }
113 }
114 rc = -EINVAL;
115out:
116 return rc;
117}
118
119/**
120 * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
121 * @daemon: Pointer to set to newly allocated daemon struct
122 * @file: File used when opening /dev/ecryptfs
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 */
129int
130ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file)
131{
132 int rc = 0;
133
134 (*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
135 if (!(*daemon)) {
136 rc = -ENOMEM;
137 goto out;
138 }
139 (*daemon)->file = file;
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,
145 &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]);
146out:
147 return rc;
148}
149
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 */
156int 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;
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);
177 mutex_unlock(&daemon->mux);
178 kzfree(daemon);
179out:
180 return rc;
181}
182
183/**
184 * ecryptfs_process_reponse
185 * @msg: The ecryptfs message received; the caller should sanity check
186 * msg->data_len and free the memory
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.
202 *
203 * Returns zero on success; non-zero otherwise
204 */
205int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
206 struct ecryptfs_message *msg, u32 seq)
207{
208 struct ecryptfs_msg_ctx *msg_ctx;
209 size_t msg_size;
210 int rc;
211
212 if (msg->index >= ecryptfs_message_buf_len) {
213 rc = -EINVAL;
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));
218 goto out;
219 }
220 msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
221 mutex_lock(&msg_ctx->mux);
222 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
223 rc = -EINVAL;
224 printk(KERN_WARNING "%s: Desired context element is not "
225 "pending a response\n", __func__);
226 goto unlock;
227 } else if (msg_ctx->counter != seq) {
228 rc = -EINVAL;
229 printk(KERN_WARNING "%s: Invalid message sequence; "
230 "expected [%d]; received [%d]\n", __func__,
231 msg_ctx->counter, seq);
232 goto unlock;
233 }
234 msg_size = (sizeof(*msg) + msg->data_len);
235 msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
236 if (!msg_ctx->msg) {
237 rc = -ENOMEM;
238 goto unlock;
239 }
240 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
241 wake_up_process(msg_ctx->task);
242 rc = 0;
243unlock:
244 mutex_unlock(&msg_ctx->mux);
245out:
246 return rc;
247}
248
249/**
250 * ecryptfs_send_message_locked
251 * @data: The data to send
252 * @data_len: The length of data
253 * @msg_ctx: The message context allocated for the send
254 *
255 * Must be called with ecryptfs_daemon_hash_mux held.
256 *
257 * Returns zero on success; non-zero otherwise
258 */
259static int
260ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
261 struct ecryptfs_msg_ctx **msg_ctx)
262{
263 struct ecryptfs_daemon *daemon;
264 int rc;
265
266 rc = ecryptfs_find_daemon_by_euid(&daemon);
267 if (rc) {
268 rc = -ENOTCONN;
269 goto out;
270 }
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);
275 printk(KERN_WARNING "%s: Could not claim a free "
276 "context element\n", __func__);
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);
282 rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
283 daemon);
284 if (rc)
285 printk(KERN_ERR "%s: Error attempting to send message to "
286 "userspace daemon; rc = [%d]\n", __func__, rc);
287out:
288 return rc;
289}
290
291/**
292 * ecryptfs_send_message
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 */
301int ecryptfs_send_message(char *data, int data_len,
302 struct ecryptfs_msg_ctx **msg_ctx)
303{
304 int rc;
305
306 mutex_lock(&ecryptfs_daemon_hash_mux);
307 rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
308 msg_ctx);
309 mutex_unlock(&ecryptfs_daemon_hash_mux);
310 return rc;
311}
312
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
322 * error occurs. Callee must free @msg on success.
323 */
324int 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
330sleep:
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
351int __init ecryptfs_init_messaging(void)
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;
358 printk(KERN_WARNING "%s: Specified number of users is "
359 "too large, defaulting to [%d] users\n", __func__,
360 ecryptfs_number_of_users);
361 }
362 mutex_init(&ecryptfs_daemon_hash_mux);
363 mutex_lock(&ecryptfs_daemon_hash_mux);
364 ecryptfs_hash_bits = 1;
365 while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
366 ecryptfs_hash_bits++;
367 ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
368 * (1 << ecryptfs_hash_bits)),
369 GFP_KERNEL);
370 if (!ecryptfs_daemon_hash) {
371 rc = -ENOMEM;
372 mutex_unlock(&ecryptfs_daemon_hash_mux);
373 goto out;
374 }
375 for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
376 INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
377 mutex_unlock(&ecryptfs_daemon_hash_mux);
378 ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
379 * ecryptfs_message_buf_len),
380 GFP_KERNEL);
381 if (!ecryptfs_msg_ctx_arr) {
382 rc = -ENOMEM;
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);
390 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
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);
403 rc = ecryptfs_init_ecryptfs_miscdev();
404 if (rc)
405 ecryptfs_release_messaging();
406out:
407 return rc;
408}
409
410void ecryptfs_release_messaging(void)
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);
418 kfree(ecryptfs_msg_ctx_arr[i].msg);
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 }
424 if (ecryptfs_daemon_hash) {
425 struct ecryptfs_daemon *daemon;
426 struct hlist_node *n;
427 int i;
428
429 mutex_lock(&ecryptfs_daemon_hash_mux);
430 for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
431 int rc;
432
433 hlist_for_each_entry_safe(daemon, n,
434 &ecryptfs_daemon_hash[i],
435 euid_chain) {
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);
443 }
444 }
445 kfree(ecryptfs_daemon_hash);
446 mutex_unlock(&ecryptfs_daemon_hash_mux);
447 }
448 ecryptfs_destroy_ecryptfs_miscdev();
449 return;
450}