fs/ecryptfs/messaging.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  *
   4  * Copyright (C) 2004-2006 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 "ecryptfs_kernel.h"
  24
  25 static LIST_HEAD(ecryptfs_msg_ctx_free_list);
  26 static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
  27 static struct mutex ecryptfs_msg_ctx_lists_mux;
  28
  29 static struct hlist_head *ecryptfs_daemon_id_hash;
  30 static struct mutex ecryptfs_daemon_id_hash_mux;
  31 static int ecryptfs_hash_buckets;
  32 #define ecryptfs_uid_hash(uid) \
  33         hash_long((unsigned long)uid, ecryptfs_hash_buckets)
  34
  35 static unsigned int ecryptfs_msg_counter;
  36 static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
  37
  38 /**
  39  * ecryptfs_acquire_free_msg_ctx
  40  * @msg_ctx: The context that was acquired from the free list
  41  *
  42  * Acquires a context element from the free list and locks the mutex
  43  * on the context.  Returns zero on success; non-zero on error or upon
  44  * failure to acquire a free context element.  Be sure to lock the
  45  * list mutex before calling.
  46  */
  47 static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
  48 {
  49         struct list_head *p;
  50         int rc;
  51
  52         if (list_empty(&ecryptfs_msg_ctx_free_list)) {
  53                 ecryptfs_printk(KERN_WARNING, "The eCryptfs free "
  54                                 "context list is empty.  It may be helpful to "
  55                                 "specify the ecryptfs_message_buf_len "
  56                                 "parameter to be greater than the current "
  57                                 "value of [%d]\n", ecryptfs_message_buf_len);
  58                 rc = -ENOMEM;
  59                 goto out;
  60         }
  61         list_for_each(p, &ecryptfs_msg_ctx_free_list) {
  62                 *msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
  63                 if (mutex_trylock(&(*msg_ctx)->mux)) {
  64                         (*msg_ctx)->task = current;
  65                         rc = 0;
  66                         goto out;
  67                 }
  68         }
  69         rc = -ENOMEM;
  70 out:
  71         return rc;
  72 }
  73
  74 /**
  75  * ecryptfs_msg_ctx_free_to_alloc
  76  * @msg_ctx: The context to move from the free list to the alloc list
  77  *
  78  * Be sure to lock the list mutex and the context mutex before
  79  * calling.
  80  */
  81 static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
  82 {
  83         list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
  84         msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
  85         msg_ctx->counter = ++ecryptfs_msg_counter;
  86 }
  87
  88 /**
  89  * ecryptfs_msg_ctx_alloc_to_free
  90  * @msg_ctx: The context to move from the alloc list to the free list
  91  *
  92  * Be sure to lock the list mutex and the context mutex before
  93  * calling.
  94  */
  95 static void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
  96 {
  97         list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
  98         if (msg_ctx->msg)
  99                 kfree(msg_ctx->msg);
 100         msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
 101 }
 102
 103 /**
 104  * ecryptfs_find_daemon_id
 105  * @uid: The user id which maps to the desired daemon id
 106  * @id: If return value is zero, points to the desired daemon id
 107  *      pointer
 108  *
 109  * Search the hash list for the given user id.  Returns zero if the
 110  * user id exists in the list; non-zero otherwise.  The daemon id hash
 111  * mutex should be held before calling this function.
 112  */
 113 static int ecryptfs_find_daemon_id(uid_t uid, struct ecryptfs_daemon_id **id)
 114 {
 115         struct hlist_node *elem;
 116         int rc;
 117
 118         hlist_for_each_entry(*id, elem,
 119                              &ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)],
 120                              id_chain) {
 121                 if ((*id)->uid == uid) {
 122                         rc = 0;
 123                         goto out;
 124                 }
 125         }
 126         rc = -EINVAL;
 127 out:
 128         return rc;
 129 }
 130
 131 static int ecryptfs_send_raw_message(unsigned int transport, u16 msg_type,
 132                                      pid_t pid)
 133 {
 134         int rc;
 135
 136         switch(transport) {
 137         case ECRYPTFS_TRANSPORT_NETLINK:
 138                 rc = ecryptfs_send_netlink(NULL, 0, NULL, msg_type, 0, pid);
 139                 break;
 140         case ECRYPTFS_TRANSPORT_CONNECTOR:
 141         case ECRYPTFS_TRANSPORT_RELAYFS:
 142         default:
 143                 rc = -ENOSYS;
 144         }
 145         return rc;
 146 }
 147
 148 /**
 149  * ecryptfs_process_helo
 150  * @transport: The underlying transport (netlink, etc.)
 151  * @uid: The user ID owner of the message
 152  * @pid: The process ID for the userspace program that sent the
 153  *       message
 154  *
 155  * Adds the uid and pid values to the daemon id hash.  If a uid
 156  * already has a daemon pid registered, the daemon will be
 157  * unregistered before the new daemon id is put into the hash list.
 158  * Returns zero after adding a new daemon id to the hash list;
 159  * non-zero otherwise.
 160  */
 161 int ecryptfs_process_helo(unsigned int transport, uid_t uid, pid_t pid)
 162 {
 163         struct ecryptfs_daemon_id *new_id;
 164         struct ecryptfs_daemon_id *old_id;
 165         int rc;
 166
 167         mutex_lock(&ecryptfs_daemon_id_hash_mux);
 168         new_id = kmalloc(sizeof(*new_id), GFP_KERNEL);
 169         if (!new_id) {
 170                 rc = -ENOMEM;
 171                 ecryptfs_printk(KERN_ERR, "Failed to allocate memory; unable "
 172                                 "to register daemon [%d] for user [%d]\n",
 173                                 pid, uid);
 174                 goto unlock;
 175         }
 176         if (!ecryptfs_find_daemon_id(uid, &old_id)) {
 177                 printk(KERN_WARNING "Received request from user [%d] "
 178                        "to register daemon [%d]; unregistering daemon "
 179                        "[%d]\n", uid, pid, old_id->pid);
 180                 hlist_del(&old_id->id_chain);
 181                 rc = ecryptfs_send_raw_message(transport, ECRYPTFS_NLMSG_QUIT,
 182                                                old_id->pid);
 183                 if (rc)
 184                         printk(KERN_WARNING "Failed to send QUIT "
 185                                "message to daemon [%d]; rc = [%d]\n",
 186                                old_id->pid, rc);
 187                 kfree(old_id);
 188         }
 189         new_id->uid = uid;
 190         new_id->pid = pid;
 191         hlist_add_head(&new_id->id_chain,
 192                        &ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)]);
 193         rc = 0;
 194 unlock:
 195         mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 196         return rc;
 197 }
 198
 199 /**
 200  * ecryptfs_process_quit
 201  * @uid: The user ID owner of the message
 202  * @pid: The process ID for the userspace program that sent the
 203  *       message
 204  *
 205  * Deletes the corresponding daemon id for the given uid and pid, if
 206  * it is the registered that is requesting the deletion. Returns zero
 207  * after deleting the desired daemon id; non-zero otherwise.
 208  */
 209 int ecryptfs_process_quit(uid_t uid, pid_t pid)
 210 {
 211         struct ecryptfs_daemon_id *id;
 212         int rc;
 213
 214         mutex_lock(&ecryptfs_daemon_id_hash_mux);
 215         if (ecryptfs_find_daemon_id(uid, &id)) {
 216                 rc = -EINVAL;
 217                 ecryptfs_printk(KERN_ERR, "Received request from user [%d] to "
 218                                 "unregister unrecognized daemon [%d]\n", uid,
 219                                 pid);
 220                 goto unlock;
 221         }
 222         if (id->pid != pid) {
 223                 rc = -EINVAL;
 224                 ecryptfs_printk(KERN_WARNING, "Received request from user [%d] "
 225                                 "with pid [%d] to unregister daemon [%d]\n",
 226                                 uid, pid, id->pid);
 227                 goto unlock;
 228         }
 229         hlist_del(&id->id_chain);
 230         kfree(id);
 231         rc = 0;
 232 unlock:
 233         mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 234         return rc;
 235 }
 236
 237 /**
 238  * ecryptfs_process_reponse
 239  * @msg: The ecryptfs message received; the caller should sanity check
 240  *       msg->data_len
 241  * @pid: The process ID of the userspace application that sent the
 242  *       message
 243  * @seq: The sequence number of the message
 244  *
 245  * Processes a response message after sending a operation request to
 246  * userspace. Returns zero upon delivery to desired context element;
 247  * non-zero upon delivery failure or error.
 248  */
 249 int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t uid,
 250                               pid_t pid, u32 seq)
 251 {
 252         struct ecryptfs_daemon_id *id;
 253         struct ecryptfs_msg_ctx *msg_ctx;
 254         int msg_size;
 255         int rc;
 256
 257         if (msg->index >= ecryptfs_message_buf_len) {
 258                 rc = -EINVAL;
 259                 ecryptfs_printk(KERN_ERR, "Attempt to reference "
 260                                 "context buffer at index [%d]; maximum "
 261                                 "allowable is [%d]\n", msg->index,
 262                                 (ecryptfs_message_buf_len - 1));
 263                 goto out;
 264         }
 265         msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
 266         mutex_lock(&msg_ctx->mux);
 267         if (ecryptfs_find_daemon_id(msg_ctx->task->euid, &id)) {
 268                 rc = -EBADMSG;
 269                 ecryptfs_printk(KERN_WARNING, "User [%d] received a "
 270                                 "message response from process [%d] but does "
 271                                 "not have a registered daemon\n",
 272                                 msg_ctx->task->euid, pid);
 273                 goto wake_up;
 274         }
 275         if (msg_ctx->task->euid != uid) {
 276                 rc = -EBADMSG;
 277                 ecryptfs_printk(KERN_WARNING, "Received message from user "
 278                                 "[%d]; expected message from user [%d]\n",
 279                                 uid, msg_ctx->task->euid);
 280                 goto unlock;
 281         }
 282         if (id->pid != pid) {
 283                 rc = -EBADMSG;
 284                 ecryptfs_printk(KERN_ERR, "User [%d] received a "
 285                                 "message response from an unrecognized "
 286                                 "process [%d]\n", msg_ctx->task->euid, pid);
 287                 goto unlock;
 288         }
 289         if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
 290                 rc = -EINVAL;
 291                 ecryptfs_printk(KERN_WARNING, "Desired context element is not "
 292                                 "pending a response\n");
 293                 goto unlock;
 294         } else if (msg_ctx->counter != seq) {
 295                 rc = -EINVAL;
 296                 ecryptfs_printk(KERN_WARNING, "Invalid message sequence; "
 297                                 "expected [%d]; received [%d]\n",
 298                                 msg_ctx->counter, seq);
 299                 goto unlock;
 300         }
 301         msg_size = sizeof(*msg) + msg->data_len;
 302         msg_ctx->msg = kmalloc(msg_size, GFP_KERNEL);
 303         if (!msg_ctx->msg) {
 304                 rc = -ENOMEM;
 305                 ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
 306                 goto unlock;
 307         }
 308         memcpy(msg_ctx->msg, msg, msg_size);
 309         msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
 310         rc = 0;
 311 wake_up:
 312         wake_up_process(msg_ctx->task);
 313 unlock:
 314         mutex_unlock(&msg_ctx->mux);
 315 out:
 316         return rc;
 317 }
 318
 319 /**
 320  * ecryptfs_send_message
 321  * @transport: The transport over which to send the message (i.e.,
 322  *             netlink)
 323  * @data: The data to send
 324  * @data_len: The length of data
 325  * @msg_ctx: The message context allocated for the send
 326  */
 327 int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
 328                           struct ecryptfs_msg_ctx **msg_ctx)
 329 {
 330         struct ecryptfs_daemon_id *id;
 331         int rc;
 332
 333         mutex_lock(&ecryptfs_daemon_id_hash_mux);
 334         if (ecryptfs_find_daemon_id(current->euid, &id)) {
 335                 mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 336                 rc = -ENOTCONN;
 337                 ecryptfs_printk(KERN_ERR, "User [%d] does not have a daemon "
 338                                 "registered\n", current->euid);
 339                 goto out;
 340         }
 341         mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 342         mutex_lock(&ecryptfs_msg_ctx_lists_mux);
 343         rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
 344         if (rc) {
 345                 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 346                 ecryptfs_printk(KERN_WARNING, "Could not claim a free "
 347                                 "context element\n");
 348                 goto out;
 349         }
 350         ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
 351         mutex_unlock(&(*msg_ctx)->mux);
 352         mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 353         switch (transport) {
 354         case ECRYPTFS_TRANSPORT_NETLINK:
 355                 rc = ecryptfs_send_netlink(data, data_len, *msg_ctx,
 356                                            ECRYPTFS_NLMSG_REQUEST, 0, id->pid);
 357                 break;
 358         case ECRYPTFS_TRANSPORT_CONNECTOR:
 359         case ECRYPTFS_TRANSPORT_RELAYFS:
 360         default:
 361                 rc = -ENOSYS;
 362         }
 363         if (rc) {
 364                 printk(KERN_ERR "Error attempting to send message to userspace "
 365                        "daemon; rc = [%d]\n", rc);
 366         }
 367 out:
 368         return rc;
 369 }
 370
 371 /**
 372  * ecryptfs_wait_for_response
 373  * @msg_ctx: The context that was assigned when sending a message
 374  * @msg: The incoming message from userspace; not set if rc != 0
 375  *
 376  * Sleeps until awaken by ecryptfs_receive_message or until the amount
 377  * of time exceeds ecryptfs_message_wait_timeout.  If zero is
 378  * returned, msg will point to a valid message from userspace; a
 379  * non-zero value is returned upon failure to receive a message or an
 380  * error occurs.
 381  */
 382 int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
 383                                struct ecryptfs_message **msg)
 384 {
 385         signed long timeout = ecryptfs_message_wait_timeout * HZ;
 386         int rc = 0;
 387
 388 sleep:
 389         timeout = schedule_timeout_interruptible(timeout);
 390         mutex_lock(&ecryptfs_msg_ctx_lists_mux);
 391         mutex_lock(&msg_ctx->mux);
 392         if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
 393                 if (timeout) {
 394                         mutex_unlock(&msg_ctx->mux);
 395                         mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 396                         goto sleep;
 397                 }
 398                 rc = -ENOMSG;
 399         } else {
 400                 *msg = msg_ctx->msg;
 401                 msg_ctx->msg = NULL;
 402         }
 403         ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
 404         mutex_unlock(&msg_ctx->mux);
 405         mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 406         return rc;
 407 }
 408
 409 int ecryptfs_init_messaging(unsigned int transport)
 410 {
 411         int i;
 412         int rc = 0;
 413
 414         if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
 415                 ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
 416                 ecryptfs_printk(KERN_WARNING, "Specified number of users is "
 417                                 "too large, defaulting to [%d] users\n",
 418                                 ecryptfs_number_of_users);
 419         }
 420         mutex_init(&ecryptfs_daemon_id_hash_mux);
 421         mutex_lock(&ecryptfs_daemon_id_hash_mux);
 422         ecryptfs_hash_buckets = 1;
 423         while (ecryptfs_number_of_users >> ecryptfs_hash_buckets)
 424                 ecryptfs_hash_buckets++;
 425         ecryptfs_daemon_id_hash = kmalloc(sizeof(struct hlist_head)
 426                                           * ecryptfs_hash_buckets, GFP_KERNEL);
 427         if (!ecryptfs_daemon_id_hash) {
 428                 rc = -ENOMEM;
 429                 ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
 430                 mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 431                 goto out;
 432         }
 433         for (i = 0; i < ecryptfs_hash_buckets; i++)
 434                 INIT_HLIST_HEAD(&ecryptfs_daemon_id_hash[i]);
 435         mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 436
 437         ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
 438                                       * ecryptfs_message_buf_len), GFP_KERNEL);
 439         if (!ecryptfs_msg_ctx_arr) {
 440                 rc = -ENOMEM;
 441                 ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
 442                 goto out;
 443         }
 444         mutex_init(&ecryptfs_msg_ctx_lists_mux);
 445         mutex_lock(&ecryptfs_msg_ctx_lists_mux);
 446         ecryptfs_msg_counter = 0;
 447         for (i = 0; i < ecryptfs_message_buf_len; i++) {
 448                 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
 449                 mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
 450                 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
 451                 ecryptfs_msg_ctx_arr[i].index = i;
 452                 ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
 453                 ecryptfs_msg_ctx_arr[i].counter = 0;
 454                 ecryptfs_msg_ctx_arr[i].task = NULL;
 455                 ecryptfs_msg_ctx_arr[i].msg = NULL;
 456                 list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
 457                               &ecryptfs_msg_ctx_free_list);
 458                 mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
 459         }
 460         mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 461         switch(transport) {
 462         case ECRYPTFS_TRANSPORT_NETLINK:
 463                 rc = ecryptfs_init_netlink();
 464                 if (rc)
 465                         ecryptfs_release_messaging(transport);
 466                 break;
 467         case ECRYPTFS_TRANSPORT_CONNECTOR:
 468         case ECRYPTFS_TRANSPORT_RELAYFS:
 469         default:
 470                 rc = -ENOSYS;
 471         }
 472 out:
 473         return rc;
 474 }
 475
 476 void ecryptfs_release_messaging(unsigned int transport)
 477 {
 478         if (ecryptfs_msg_ctx_arr) {
 479                 int i;
 480
 481                 mutex_lock(&ecryptfs_msg_ctx_lists_mux);
 482                 for (i = 0; i < ecryptfs_message_buf_len; i++) {
 483                         mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
 484                         if (ecryptfs_msg_ctx_arr[i].msg)
 485                                 kfree(ecryptfs_msg_ctx_arr[i].msg);
 486                         mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
 487                 }
 488                 kfree(ecryptfs_msg_ctx_arr);
 489                 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 490         }
 491         if (ecryptfs_daemon_id_hash) {
 492                 struct hlist_node *elem;
 493                 struct ecryptfs_daemon_id *id;
 494                 int i;
 495
 496                 mutex_lock(&ecryptfs_daemon_id_hash_mux);
 497                 for (i = 0; i < ecryptfs_hash_buckets; i++) {
 498                         hlist_for_each_entry(id, elem,
 499                                              &ecryptfs_daemon_id_hash[i],
 500                                              id_chain) {
 501                                 hlist_del(elem);
 502                                 kfree(id);
 503                         }
 504                 }
 505                 kfree(ecryptfs_daemon_id_hash);
 506                 mutex_unlock(&ecryptfs_daemon_id_hash_mux);
 507         }
 508         switch(transport) {
 509         case ECRYPTFS_TRANSPORT_NETLINK:
 510                 ecryptfs_release_netlink();
 511                 break;
 512         case ECRYPTFS_TRANSPORT_CONNECTOR:
 513         case ECRYPTFS_TRANSPORT_RELAYFS:
 514         default:
 515                 break;
 516         }
 517         return;
 518 }