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 struct mutex ecryptfs_msg_ctx_lists_mux; 18 19 static struct hlist_head *ecryptfs_daemon_hash; 20 struct 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 kzfree(daemon); 179 out: 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 */ 205 int 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; 243 unlock: 244 mutex_unlock(&msg_ctx->mux); 245 out: 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 */ 259 static int 260 ecryptfs_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); 287 out: 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 */ 301 int 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 */ 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 } 350 351 int __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 kfree(ecryptfs_daemon_hash); 383 rc = -ENOMEM; 384 goto out; 385 } 386 mutex_init(&ecryptfs_msg_ctx_lists_mux); 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