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 <code@tyhicks.com>
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
15 static LIST_HEAD(ecryptfs_msg_ctx_free_list);
16 static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
17 static DEFINE_MUTEX(ecryptfs_msg_ctx_lists_mux);
18
19 static struct hlist_head *ecryptfs_daemon_hash;
20 DEFINE_MUTEX(ecryptfs_daemon_hash_mux);
21 static 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
25 static u32 ecryptfs_msg_counter;
26 static 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 */
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)) {
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;
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 *
69 * Must be called with ecryptfs_msg_ctx_lists_mux held.
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 *
82 * Must be called with ecryptfs_msg_ctx_lists_mux held.
83 */
84 void 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 */
102 int 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;
115 out:
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 */
129 int
130 ecryptfs_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()]);
146 out:
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 */
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;
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 kfree_sensitive(daemon);
179 out:
180 return rc;
181 }
182
183 /**
184 * ecryptfs_process_response
185 * @daemon: eCryptfs daemon object
186 * @msg: The ecryptfs message received; the caller should sanity check
187 * msg->data_len and free the memory
188 * @seq: The sequence number of the message; must match the sequence
189 * number for the existing message context waiting for this
190 * response
191 *
192 * Processes a response message after sending an operation request to
193 * userspace. Some other process is awaiting this response. Before
194 * sending out its first communications, the other process allocated a
195 * msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
196 * response message contains this index so that we can copy over the
197 * response message into the msg_ctx that the process holds a
198 * reference to. The other process is going to wake up, check to see
199 * that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
200 * proceed to read off and process the response message. Returns zero
201 * upon delivery to desired context element; non-zero upon delivery
202 * failure or error.
203 *
204 * Returns zero on success; non-zero otherwise
205 */
206 int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
207 struct ecryptfs_message *msg, u32 seq)
208 {
209 struct ecryptfs_msg_ctx *msg_ctx;
210 size_t msg_size;
211 int rc;
212
213 if (msg->index >= ecryptfs_message_buf_len) {
214 rc = -EINVAL;
215 printk(KERN_ERR "%s: Attempt to reference "
216 "context buffer at index [%d]; maximum "
217 "allowable is [%d]\n", __func__, msg->index,
218 (ecryptfs_message_buf_len - 1));
219 goto out;
220 }
221 msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
222 mutex_lock(&msg_ctx->mux);
223 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
224 rc = -EINVAL;
225 printk(KERN_WARNING "%s: Desired context element is not "
226 "pending a response\n", __func__);
227 goto unlock;
228 } else if (msg_ctx->counter != seq) {
229 rc = -EINVAL;
230 printk(KERN_WARNING "%s: Invalid message sequence; "
231 "expected [%d]; received [%d]\n", __func__,
232 msg_ctx->counter, seq);
233 goto unlock;
234 }
235 msg_size = (sizeof(*msg) + msg->data_len);
236 msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
237 if (!msg_ctx->msg) {
238 rc = -ENOMEM;
239 goto unlock;
240 }
241 msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
242 wake_up_process(msg_ctx->task);
243 rc = 0;
244 unlock:
245 mutex_unlock(&msg_ctx->mux);
246 out:
247 return rc;
248 }
249
250 /**
251 * ecryptfs_send_message_locked
252 * @data: The data to send
253 * @data_len: The length of data
254 * @msg_type: Type of message
255 * @msg_ctx: The message context allocated for the send
256 *
257 * Must be called with ecryptfs_daemon_hash_mux held.
258 *
259 * Returns zero on success; non-zero otherwise
260 */
261 static int
262 ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
263 struct ecryptfs_msg_ctx **msg_ctx)
264 {
265 struct ecryptfs_daemon *daemon;
266 int rc;
267
268 rc = ecryptfs_find_daemon_by_euid(&daemon);
269 if (rc) {
270 rc = -ENOTCONN;
271 goto out;
272 }
273 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
274 rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
275 if (rc) {
276 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
277 printk(KERN_WARNING "%s: Could not claim a free "
278 "context element\n", __func__);
279 goto out;
280 }
281 ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
282 mutex_unlock(&(*msg_ctx)->mux);
283 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
284 rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
285 daemon);
286 if (rc)
287 printk(KERN_ERR "%s: Error attempting to send message to "
288 "userspace daemon; rc = [%d]\n", __func__, rc);
289 out:
290 return rc;
291 }
292
293 /**
294 * ecryptfs_send_message
295 * @data: The data to send
296 * @data_len: The length of data
297 * @msg_ctx: The message context allocated for the send
298 *
299 * Grabs ecryptfs_daemon_hash_mux.
300 *
301 * Returns zero on success; non-zero otherwise
302 */
303 int ecryptfs_send_message(char *data, int data_len,
304 struct ecryptfs_msg_ctx **msg_ctx)
305 {
306 int rc;
307
308 mutex_lock(&ecryptfs_daemon_hash_mux);
309 rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
310 msg_ctx);
311 mutex_unlock(&ecryptfs_daemon_hash_mux);
312 return rc;
313 }
314
315 /**
316 * ecryptfs_wait_for_response
317 * @msg_ctx: The context that was assigned when sending a message
318 * @msg: The incoming message from userspace; not set if rc != 0
319 *
320 * Sleeps until awaken by ecryptfs_receive_message or until the amount
321 * of time exceeds ecryptfs_message_wait_timeout. If zero is
322 * returned, msg will point to a valid message from userspace; a
323 * non-zero value is returned upon failure to receive a message or an
324 * error occurs. Callee must free @msg on success.
325 */
326 int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
327 struct ecryptfs_message **msg)
328 {
329 signed long timeout = ecryptfs_message_wait_timeout * HZ;
330 int rc = 0;
331
332 sleep:
333 timeout = schedule_timeout_interruptible(timeout);
334 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
335 mutex_lock(&msg_ctx->mux);
336 if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
337 if (timeout) {
338 mutex_unlock(&msg_ctx->mux);
339 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
340 goto sleep;
341 }
342 rc = -ENOMSG;
343 } else {
344 *msg = msg_ctx->msg;
345 msg_ctx->msg = NULL;
346 }
347 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
348 mutex_unlock(&msg_ctx->mux);
349 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
350 return rc;
351 }
352
353 int __init ecryptfs_init_messaging(void)
354 {
355 int i;
356 int rc = 0;
357
358 if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
359 ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
360 printk(KERN_WARNING "%s: Specified number of users is "
361 "too large, defaulting to [%d] users\n", __func__,
362 ecryptfs_number_of_users);
363 }
364 mutex_lock(&ecryptfs_daemon_hash_mux);
365 ecryptfs_hash_bits = 1;
366 while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
367 ecryptfs_hash_bits++;
368 ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
369 * (1 << ecryptfs_hash_bits)),
370 GFP_KERNEL);
371 if (!ecryptfs_daemon_hash) {
372 rc = -ENOMEM;
373 mutex_unlock(&ecryptfs_daemon_hash_mux);
374 goto out;
375 }
376 for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
377 INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
378 mutex_unlock(&ecryptfs_daemon_hash_mux);
379 ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
380 * ecryptfs_message_buf_len),
381 GFP_KERNEL);
382 if (!ecryptfs_msg_ctx_arr) {
383 kfree(ecryptfs_daemon_hash);
384 rc = -ENOMEM;
385 goto out;
386 }
387 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
388 ecryptfs_msg_counter = 0;
389 for (i = 0; i < ecryptfs_message_buf_len; i++) {
390 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
391 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
392 mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
393 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
394 ecryptfs_msg_ctx_arr[i].index = i;
395 ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
396 ecryptfs_msg_ctx_arr[i].counter = 0;
397 ecryptfs_msg_ctx_arr[i].task = NULL;
398 ecryptfs_msg_ctx_arr[i].msg = NULL;
399 list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
400 &ecryptfs_msg_ctx_free_list);
401 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
402 }
403 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
404 rc = ecryptfs_init_ecryptfs_miscdev();
405 if (rc)
406 ecryptfs_release_messaging();
407 out:
408 return rc;
409 }
410
411 void ecryptfs_release_messaging(void)
412 {
413 if (ecryptfs_msg_ctx_arr) {
414 int i;
415
416 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
417 for (i = 0; i < ecryptfs_message_buf_len; i++) {
418 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
419 kfree(ecryptfs_msg_ctx_arr[i].msg);
420 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
421 }
422 kfree(ecryptfs_msg_ctx_arr);
423 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
424 }
425 if (ecryptfs_daemon_hash) {
426 struct ecryptfs_daemon *daemon;
427 struct hlist_node *n;
428 int i;
429
430 mutex_lock(&ecryptfs_daemon_hash_mux);
431 for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
432 int rc;
433
434 hlist_for_each_entry_safe(daemon, n,
435 &ecryptfs_daemon_hash[i],
436 euid_chain) {
437 rc = ecryptfs_exorcise_daemon(daemon);
438 if (rc)
439 printk(KERN_ERR "%s: Error whilst "
440 "attempting to destroy daemon; "
441 "rc = [%d]. Dazed and confused, "
442 "but trying to continue.\n",
443 __func__, rc);
444 }
445 }
446 kfree(ecryptfs_daemon_hash);
447 mutex_unlock(&ecryptfs_daemon_hash_mux);
448 }
449 ecryptfs_destroy_ecryptfs_miscdev();
450 return;
451 }
452
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