1/** 2 * eCryptfs: Linux filesystem encryption layer 3 * 4 * Copyright (C) 2008 International Business Machines Corp. 5 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License version 9 * 2 as published by the Free Software Foundation. 10 * 11 * This program is distributed in the hope that it will be useful, but 12 * WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 19 * 02111-1307, USA. 20 */ 21 22#include <linux/fs.h> 23#include <linux/hash.h> 24#include <linux/random.h> 25#include <linux/miscdevice.h> 26#include <linux/poll.h> 27#include <linux/slab.h> 28#include <linux/wait.h> 29#include <linux/module.h> 30#include "ecryptfs_kernel.h" 31 32static atomic_t ecryptfs_num_miscdev_opens; 33 34/** 35 * ecryptfs_miscdev_poll 36 * @file: dev file (ignored) 37 * @pt: dev poll table (ignored) 38 * 39 * Returns the poll mask 40 */ 41static unsigned int 42ecryptfs_miscdev_poll(struct file *file, poll_table *pt) 43{ 44 struct ecryptfs_daemon *daemon; 45 unsigned int mask = 0; 46 uid_t euid = current_euid(); 47 int rc; 48 49 mutex_lock(&ecryptfs_daemon_hash_mux); 50 /* TODO: Just use file->private_data? */ 51 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); 52 BUG_ON(rc || !daemon); 53 mutex_lock(&daemon->mux); 54 mutex_unlock(&ecryptfs_daemon_hash_mux); 55 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { 56 printk(KERN_WARNING "%s: Attempt to poll on zombified " 57 "daemon\n", __func__); 58 goto out_unlock_daemon; 59 } 60 if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) 61 goto out_unlock_daemon; 62 if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL) 63 goto out_unlock_daemon; 64 daemon->flags |= ECRYPTFS_DAEMON_IN_POLL; 65 mutex_unlock(&daemon->mux); 66 poll_wait(file, &daemon->wait, pt); 67 mutex_lock(&daemon->mux); 68 if (!list_empty(&daemon->msg_ctx_out_queue)) 69 mask |= POLLIN | POLLRDNORM; 70out_unlock_daemon: 71 daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL; 72 mutex_unlock(&daemon->mux); 73 return mask; 74} 75 76/** 77 * ecryptfs_miscdev_open 78 * @inode: inode of miscdev handle (ignored) 79 * @file: file for miscdev handle (ignored) 80 * 81 * Returns zero on success; non-zero otherwise 82 */ 83static int 84ecryptfs_miscdev_open(struct inode *inode, struct file *file) 85{ 86 struct ecryptfs_daemon *daemon = NULL; 87 uid_t euid = current_euid(); 88 int rc; 89 90 mutex_lock(&ecryptfs_daemon_hash_mux); 91 rc = try_module_get(THIS_MODULE); 92 if (rc == 0) { 93 rc = -EIO; 94 printk(KERN_ERR "%s: Error attempting to increment module use " 95 "count; rc = [%d]\n", __func__, rc); 96 goto out_unlock_daemon_list; 97 } 98 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); 99 if (rc || !daemon) { 100 rc = ecryptfs_spawn_daemon(&daemon, euid, current_user_ns(), 101 task_pid(current)); 102 if (rc) { 103 printk(KERN_ERR "%s: Error attempting to spawn daemon; " 104 "rc = [%d]\n", __func__, rc); 105 goto out_module_put_unlock_daemon_list; 106 } 107 } 108 mutex_lock(&daemon->mux); 109 if (daemon->pid != task_pid(current)) { 110 rc = -EINVAL; 111 printk(KERN_ERR "%s: pid [0x%p] has registered with euid [%d], " 112 "but pid [0x%p] has attempted to open the handle " 113 "instead\n", __func__, daemon->pid, daemon->euid, 114 task_pid(current)); 115 goto out_unlock_daemon; 116 } 117 if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) { 118 rc = -EBUSY; 119 printk(KERN_ERR "%s: Miscellaneous device handle may only be " 120 "opened once per daemon; pid [0x%p] already has this " 121 "handle open\n", __func__, daemon->pid); 122 goto out_unlock_daemon; 123 } 124 daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN; 125 atomic_inc(&ecryptfs_num_miscdev_opens); 126out_unlock_daemon: 127 mutex_unlock(&daemon->mux); 128out_module_put_unlock_daemon_list: 129 if (rc) 130 module_put(THIS_MODULE); 131out_unlock_daemon_list: 132 mutex_unlock(&ecryptfs_daemon_hash_mux); 133 return rc; 134} 135 136/** 137 * ecryptfs_miscdev_release 138 * @inode: inode of fs/ecryptfs/euid handle (ignored) 139 * @file: file for fs/ecryptfs/euid handle (ignored) 140 * 141 * This keeps the daemon registered until the daemon sends another 142 * ioctl to fs/ecryptfs/ctl or until the kernel module unregisters. 143 * 144 * Returns zero on success; non-zero otherwise 145 */ 146static int 147ecryptfs_miscdev_release(struct inode *inode, struct file *file) 148{ 149 struct ecryptfs_daemon *daemon = NULL; 150 uid_t euid = current_euid(); 151 int rc; 152 153 mutex_lock(&ecryptfs_daemon_hash_mux); 154 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); 155 BUG_ON(rc || !daemon); 156 mutex_lock(&daemon->mux); 157 BUG_ON(daemon->pid != task_pid(current)); 158 BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN)); 159 daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN; 160 atomic_dec(&ecryptfs_num_miscdev_opens); 161 mutex_unlock(&daemon->mux); 162 rc = ecryptfs_exorcise_daemon(daemon); 163 if (rc) { 164 printk(KERN_CRIT "%s: Fatal error whilst attempting to " 165 "shut down daemon; rc = [%d]. Please report this " 166 "bug.\n", __func__, rc); 167 BUG(); 168 } 169 module_put(THIS_MODULE); 170 mutex_unlock(&ecryptfs_daemon_hash_mux); 171 return rc; 172} 173 174/** 175 * ecryptfs_send_miscdev 176 * @data: Data to send to daemon; may be NULL 177 * @data_size: Amount of data to send to daemon 178 * @msg_ctx: Message context, which is used to handle the reply. If 179 * this is NULL, then we do not expect a reply. 180 * @msg_type: Type of message 181 * @msg_flags: Flags for message 182 * @daemon: eCryptfs daemon object 183 * 184 * Add msg_ctx to queue and then, if it exists, notify the blocked 185 * miscdevess about the data being available. Must be called with 186 * ecryptfs_daemon_hash_mux held. 187 * 188 * Returns zero on success; non-zero otherwise 189 */ 190int ecryptfs_send_miscdev(char *data, size_t data_size, 191 struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type, 192 u16 msg_flags, struct ecryptfs_daemon *daemon) 193{ 194 int rc = 0; 195 196 mutex_lock(&msg_ctx->mux); 197 msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size), 198 GFP_KERNEL); 199 if (!msg_ctx->msg) { 200 rc = -ENOMEM; 201 printk(KERN_ERR "%s: Out of memory whilst attempting " 202 "to kmalloc(%zd, GFP_KERNEL)\n", __func__, 203 (sizeof(*msg_ctx->msg) + data_size)); 204 goto out_unlock; 205 } 206 msg_ctx->msg->index = msg_ctx->index; 207 msg_ctx->msg->data_len = data_size; 208 msg_ctx->type = msg_type; 209 memcpy(msg_ctx->msg->data, data, data_size); 210 msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size); 211 mutex_lock(&daemon->mux); 212 list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue); 213 daemon->num_queued_msg_ctx++; 214 wake_up_interruptible(&daemon->wait); 215 mutex_unlock(&daemon->mux); 216out_unlock: 217 mutex_unlock(&msg_ctx->mux); 218 return rc; 219} 220 221/** 222 * ecryptfs_miscdev_read - format and send message from queue 223 * @file: fs/ecryptfs/euid miscdevfs handle (ignored) 224 * @buf: User buffer into which to copy the next message on the daemon queue 225 * @count: Amount of space available in @buf 226 * @ppos: Offset in file (ignored) 227 * 228 * Pulls the most recent message from the daemon queue, formats it for 229 * being sent via a miscdevfs handle, and copies it into @buf 230 * 231 * Returns the number of bytes copied into the user buffer 232 */ 233static ssize_t 234ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count, 235 loff_t *ppos) 236{ 237 struct ecryptfs_daemon *daemon; 238 struct ecryptfs_msg_ctx *msg_ctx; 239 size_t packet_length_size; 240 char packet_length[3]; 241 size_t i; 242 size_t total_length; 243 uid_t euid = current_euid(); 244 int rc; 245 246 mutex_lock(&ecryptfs_daemon_hash_mux); 247 /* TODO: Just use file->private_data? */ 248 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); 249 BUG_ON(rc || !daemon); 250 mutex_lock(&daemon->mux); 251 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { 252 rc = 0; 253 mutex_unlock(&ecryptfs_daemon_hash_mux); 254 printk(KERN_WARNING "%s: Attempt to read from zombified " 255 "daemon\n", __func__); 256 goto out_unlock_daemon; 257 } 258 if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) { 259 rc = 0; 260 mutex_unlock(&ecryptfs_daemon_hash_mux); 261 goto out_unlock_daemon; 262 } 263 /* This daemon will not go away so long as this flag is set */ 264 daemon->flags |= ECRYPTFS_DAEMON_IN_READ; 265 mutex_unlock(&ecryptfs_daemon_hash_mux); 266check_list: 267 if (list_empty(&daemon->msg_ctx_out_queue)) { 268 mutex_unlock(&daemon->mux); 269 rc = wait_event_interruptible( 270 daemon->wait, !list_empty(&daemon->msg_ctx_out_queue)); 271 mutex_lock(&daemon->mux); 272 if (rc < 0) { 273 rc = 0; 274 goto out_unlock_daemon; 275 } 276 } 277 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { 278 rc = 0; 279 goto out_unlock_daemon; 280 } 281 if (list_empty(&daemon->msg_ctx_out_queue)) { 282 /* Something else jumped in since the 283 * wait_event_interruptable() and removed the 284 * message from the queue; try again */ 285 goto check_list; 286 } 287 BUG_ON(euid != daemon->euid); 288 BUG_ON(current_user_ns() != daemon->user_ns); 289 BUG_ON(task_pid(current) != daemon->pid); 290 msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue, 291 struct ecryptfs_msg_ctx, daemon_out_list); 292 BUG_ON(!msg_ctx); 293 mutex_lock(&msg_ctx->mux); 294 if (msg_ctx->msg) { 295 rc = ecryptfs_write_packet_length(packet_length, 296 msg_ctx->msg_size, 297 &packet_length_size); 298 if (rc) { 299 rc = 0; 300 printk(KERN_WARNING "%s: Error writing packet length; " 301 "rc = [%d]\n", __func__, rc); 302 goto out_unlock_msg_ctx; 303 } 304 } else { 305 packet_length_size = 0; 306 msg_ctx->msg_size = 0; 307 } 308 /* miscdevfs packet format: 309 * Octet 0: Type 310 * Octets 1-4: network byte order msg_ctx->counter 311 * Octets 5-N0: Size of struct ecryptfs_message to follow 312 * Octets N0-N1: struct ecryptfs_message (including data) 313 * 314 * Octets 5-N1 not written if the packet type does not 315 * include a message */ 316 total_length = (1 + 4 + packet_length_size + msg_ctx->msg_size); 317 if (count < total_length) { 318 rc = 0; 319 printk(KERN_WARNING "%s: Only given user buffer of " 320 "size [%zd], but we need [%zd] to read the " 321 "pending message\n", __func__, count, total_length); 322 goto out_unlock_msg_ctx; 323 } 324 rc = -EFAULT; 325 if (put_user(msg_ctx->type, buf)) 326 goto out_unlock_msg_ctx; 327 if (put_user(cpu_to_be32(msg_ctx->counter), (__be32 __user *)(buf + 1))) 328 goto out_unlock_msg_ctx; 329 i = 5; 330 if (msg_ctx->msg) { 331 if (copy_to_user(&buf[i], packet_length, packet_length_size)) 332 goto out_unlock_msg_ctx; 333 i += packet_length_size; 334 if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size)) 335 goto out_unlock_msg_ctx; 336 i += msg_ctx->msg_size; 337 } 338 rc = i; 339 list_del(&msg_ctx->daemon_out_list); 340 kfree(msg_ctx->msg); 341 msg_ctx->msg = NULL; 342 /* We do not expect a reply from the userspace daemon for any 343 * message type other than ECRYPTFS_MSG_REQUEST */ 344 if (msg_ctx->type != ECRYPTFS_MSG_REQUEST) 345 ecryptfs_msg_ctx_alloc_to_free(msg_ctx); 346out_unlock_msg_ctx: 347 mutex_unlock(&msg_ctx->mux); 348out_unlock_daemon: 349 daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ; 350 mutex_unlock(&daemon->mux); 351 return rc; 352} 353 354/** 355 * ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon 356 * @data: Bytes comprising struct ecryptfs_message 357 * @data_size: sizeof(struct ecryptfs_message) + data len 358 * @euid: Effective user id of miscdevess sending the miscdev response 359 * @user_ns: The namespace in which @euid applies 360 * @pid: Miscdevess id of miscdevess sending the miscdev response 361 * @seq: Sequence number for miscdev response packet 362 * 363 * Returns zero on success; non-zero otherwise 364 */ 365static int ecryptfs_miscdev_response(char *data, size_t data_size, 366 uid_t euid, struct user_namespace *user_ns, 367 struct pid *pid, u32 seq) 368{ 369 struct ecryptfs_message *msg = (struct ecryptfs_message *)data; 370 int rc; 371 372 if ((sizeof(*msg) + msg->data_len) != data_size) { 373 printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = " 374 "[%zd]; data_size = [%zd]. Invalid packet.\n", __func__, 375 (sizeof(*msg) + msg->data_len), data_size); 376 rc = -EINVAL; 377 goto out; 378 } 379 rc = ecryptfs_process_response(msg, euid, user_ns, pid, seq); 380 if (rc) 381 printk(KERN_ERR 382 "Error processing response message; rc = [%d]\n", rc); 383out: 384 return rc; 385} 386 387/** 388 * ecryptfs_miscdev_write - handle write to daemon miscdev handle 389 * @file: File for misc dev handle (ignored) 390 * @buf: Buffer containing user data 391 * @count: Amount of data in @buf 392 * @ppos: Pointer to offset in file (ignored) 393 * 394 * miscdevfs packet format: 395 * Octet 0: Type 396 * Octets 1-4: network byte order msg_ctx->counter (0's for non-response) 397 * Octets 5-N0: Size of struct ecryptfs_message to follow 398 * Octets N0-N1: struct ecryptfs_message (including data) 399 * 400 * Returns the number of bytes read from @buf 401 */ 402static ssize_t 403ecryptfs_miscdev_write(struct file *file, const char __user *buf, 404 size_t count, loff_t *ppos) 405{ 406 __be32 counter_nbo; 407 u32 seq; 408 size_t packet_size, packet_size_length, i; 409 ssize_t sz = 0; 410 char *data; 411 uid_t euid = current_euid(); 412 int rc; 413 414 if (count == 0) 415 goto out; 416 417 data = memdup_user(buf, count); 418 if (IS_ERR(data)) { 419 printk(KERN_ERR "%s: memdup_user returned error [%ld]\n", 420 __func__, PTR_ERR(data)); 421 goto out; 422 } 423 sz = count; 424 i = 0; 425 switch (data[i++]) { 426 case ECRYPTFS_MSG_RESPONSE: 427 if (count < (1 + 4 + 1 + sizeof(struct ecryptfs_message))) { 428 printk(KERN_WARNING "%s: Minimum acceptable packet " 429 "size is [%zd], but amount of data written is " 430 "only [%zd]. Discarding response packet.\n", 431 __func__, 432 (1 + 4 + 1 + sizeof(struct ecryptfs_message)), 433 count); 434 goto out_free; 435 } 436 memcpy(&counter_nbo, &data[i], 4); 437 seq = be32_to_cpu(counter_nbo); 438 i += 4; 439 rc = ecryptfs_parse_packet_length(&data[i], &packet_size, 440 &packet_size_length); 441 if (rc) { 442 printk(KERN_WARNING "%s: Error parsing packet length; " 443 "rc = [%d]\n", __func__, rc); 444 goto out_free; 445 } 446 i += packet_size_length; 447 if ((1 + 4 + packet_size_length + packet_size) != count) { 448 printk(KERN_WARNING "%s: (1 + packet_size_length([%zd])" 449 " + packet_size([%zd]))([%zd]) != " 450 "count([%zd]). Invalid packet format.\n", 451 __func__, packet_size_length, packet_size, 452 (1 + packet_size_length + packet_size), count); 453 goto out_free; 454 } 455 rc = ecryptfs_miscdev_response(&data[i], packet_size, 456 euid, current_user_ns(), 457 task_pid(current), seq); 458 if (rc) 459 printk(KERN_WARNING "%s: Failed to deliver miscdev " 460 "response to requesting operation; rc = [%d]\n", 461 __func__, rc); 462 break; 463 case ECRYPTFS_MSG_HELO: 464 case ECRYPTFS_MSG_QUIT: 465 break; 466 default: 467 ecryptfs_printk(KERN_WARNING, "Dropping miscdev " 468 "message of unrecognized type [%d]\n", 469 data[0]); 470 break; 471 } 472out_free: 473 kfree(data); 474out: 475 return sz; 476} 477 478 479static const struct file_operations ecryptfs_miscdev_fops = { 480 .open = ecryptfs_miscdev_open, 481 .poll = ecryptfs_miscdev_poll, 482 .read = ecryptfs_miscdev_read, 483 .write = ecryptfs_miscdev_write, 484 .release = ecryptfs_miscdev_release, 485}; 486 487static struct miscdevice ecryptfs_miscdev = { 488 .minor = MISC_DYNAMIC_MINOR, 489 .name = "ecryptfs", 490 .fops = &ecryptfs_miscdev_fops 491}; 492 493/** 494 * ecryptfs_init_ecryptfs_miscdev 495 * 496 * Messages sent to the userspace daemon from the kernel are placed on 497 * a queue associated with the daemon. The next read against the 498 * miscdev handle by that daemon will return the oldest message placed 499 * on the message queue for the daemon. 500 * 501 * Returns zero on success; non-zero otherwise 502 */ 503int __init ecryptfs_init_ecryptfs_miscdev(void) 504{ 505 int rc; 506 507 atomic_set(&ecryptfs_num_miscdev_opens, 0); 508 rc = misc_register(&ecryptfs_miscdev); 509 if (rc) 510 printk(KERN_ERR "%s: Failed to register miscellaneous device " 511 "for communications with userspace daemons; rc = [%d]\n", 512 __func__, rc); 513 return rc; 514} 515 516/** 517 * ecryptfs_destroy_ecryptfs_miscdev 518 * 519 * All of the daemons must be exorcised prior to calling this 520 * function. 521 */ 522void ecryptfs_destroy_ecryptfs_miscdev(void) 523{ 524 BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0); 525 misc_deregister(&ecryptfs_miscdev); 526} 527