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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * eCryptfs: Linux filesystem encryption layer4 *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 15static LIST_HEAD(ecryptfs_msg_ctx_free_list);16static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);17static DEFINE_MUTEX(ecryptfs_msg_ctx_lists_mux);18 19static struct hlist_head *ecryptfs_daemon_hash;20DEFINE_MUTEX(ecryptfs_daemon_hash_mux);21static 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 25static u32 ecryptfs_msg_counter;26static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;27 28/**29 * ecryptfs_acquire_free_msg_ctx30 * @msg_ctx: The context that was acquired from the free list31 *32 * Acquires a context element from the free list and locks the mutex33 * on the context. Sets the msg_ctx task to current. Returns zero on34 * success; non-zero on error or upon failure to acquire a free35 * context element. Must be called with ecryptfs_msg_ctx_lists_mux36 * held.37 */38static 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;61out:62 return rc;63}64 65/**66 * ecryptfs_msg_ctx_free_to_alloc67 * @msg_ctx: The context to move from the free list to the alloc list68 *69 * Must be called with ecryptfs_msg_ctx_lists_mux held.70 */71static 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_free80 * @msg_ctx: The context to move from the alloc list to the free list81 *82 * Must be called with ecryptfs_msg_ctx_lists_mux held.83 */84void 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_euid94 * @daemon: If return value is zero, points to the desired daemon pointer95 *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 */102int 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;115out:116 return rc;117}118 119/**120 * ecryptfs_spawn_daemon - Create and initialize a new daemon struct121 * @daemon: Pointer to set to newly allocated daemon struct122 * @file: File used when opening /dev/ecryptfs123 *124 * Must be called ceremoniously while in possession of125 * ecryptfs_sacred_daemon_hash_mux126 *127 * Returns zero on success; non-zero otherwise128 */129int130ecryptfs_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()]);146out:147 return rc;148}149 150/*151 * ecryptfs_exorcise_daemon - Destroy the daemon struct152 *153 * Must be called ceremoniously while in possession of154 * ecryptfs_daemon_hash_mux and the daemon's own mux.155 */156int 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);179out:180 return rc;181}182 183/**184 * ecryptfs_process_response185 * @daemon: eCryptfs daemon object186 * @msg: The ecryptfs message received; the caller should sanity check187 * msg->data_len and free the memory188 * @seq: The sequence number of the message; must match the sequence189 * number for the existing message context waiting for this190 * response191 *192 * Processes a response message after sending an operation request to193 * userspace. Some other process is awaiting this response. Before194 * sending out its first communications, the other process allocated a195 * msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The196 * response message contains this index so that we can copy over the197 * response message into the msg_ctx that the process holds a198 * reference to. The other process is going to wake up, check to see199 * that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then200 * proceed to read off and process the response message. Returns zero201 * upon delivery to desired context element; non-zero upon delivery202 * failure or error.203 *204 * Returns zero on success; non-zero otherwise205 */206int 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;244unlock:245 mutex_unlock(&msg_ctx->mux);246out:247 return rc;248}249 250/**251 * ecryptfs_send_message_locked252 * @data: The data to send253 * @data_len: The length of data254 * @msg_type: Type of message255 * @msg_ctx: The message context allocated for the send256 *257 * Must be called with ecryptfs_daemon_hash_mux held.258 *259 * Returns zero on success; non-zero otherwise260 */261static int262ecryptfs_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);289out:290 return rc;291}292 293/**294 * ecryptfs_send_message295 * @data: The data to send296 * @data_len: The length of data297 * @msg_ctx: The message context allocated for the send298 *299 * Grabs ecryptfs_daemon_hash_mux.300 *301 * Returns zero on success; non-zero otherwise302 */303int 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_response317 * @msg_ctx: The context that was assigned when sending a message318 * @msg: The incoming message from userspace; not set if rc != 0319 *320 * Sleeps until awaken by ecryptfs_receive_message or until the amount321 * of time exceeds ecryptfs_message_wait_timeout. If zero is322 * returned, msg will point to a valid message from userspace; a323 * non-zero value is returned upon failure to receive a message or an324 * error occurs. Callee must free @msg on success.325 */326int 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 332sleep: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 353int __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();407out:408 return rc;409}410 411void 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