fs/ecryptfs/messaging.c

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This source file includes following definitions.
ecryptfs_acquire_free_msg_ctx
ecryptfs_msg_ctx_free_to_alloc
ecryptfs_msg_ctx_alloc_to_free
ecryptfs_find_daemon_by_euid
ecryptfs_spawn_daemon
ecryptfs_exorcise_daemon
ecryptfs_process_response
ecryptfs_send_message_locked
ecryptfs_send_message
ecryptfs_wait_for_response
ecryptfs_init_messaging
ecryptfs_release_messaging
   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 
  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 }
/* [<][>][^][v][top][bottom][index][help] */
root/fs/ecryptfs/messaging.c

DEFINITIONS
