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linux-next/fs/ecryptfs/messaging.c
Thomas Gleixner 4505153954 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not write to the free
  software foundation inc 59 temple place suite 330 boston ma 02111
  1307 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 136 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190530000436.384967451@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:37:06 +02:00

451 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/**
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 2004-2008 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
* Tyler Hicks <tyhicks@ou.edu>
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include <linux/nsproxy.h>
#include "ecryptfs_kernel.h"
static LIST_HEAD(ecryptfs_msg_ctx_free_list);
static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
static struct mutex ecryptfs_msg_ctx_lists_mux;
static struct hlist_head *ecryptfs_daemon_hash;
struct mutex ecryptfs_daemon_hash_mux;
static int ecryptfs_hash_bits;
#define ecryptfs_current_euid_hash(uid) \
hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)
static u32 ecryptfs_msg_counter;
static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
/**
* ecryptfs_acquire_free_msg_ctx
* @msg_ctx: The context that was acquired from the free list
*
* Acquires a context element from the free list and locks the mutex
* on the context. Sets the msg_ctx task to current. Returns zero on
* success; non-zero on error or upon failure to acquire a free
* context element. Must be called with ecryptfs_msg_ctx_lists_mux
* held.
*/
static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
{
struct list_head *p;
int rc;
if (list_empty(&ecryptfs_msg_ctx_free_list)) {
printk(KERN_WARNING "%s: The eCryptfs free "
"context list is empty. It may be helpful to "
"specify the ecryptfs_message_buf_len "
"parameter to be greater than the current "
"value of [%d]\n", __func__, ecryptfs_message_buf_len);
rc = -ENOMEM;
goto out;
}
list_for_each(p, &ecryptfs_msg_ctx_free_list) {
*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
if (mutex_trylock(&(*msg_ctx)->mux)) {
(*msg_ctx)->task = current;
rc = 0;
goto out;
}
}
rc = -ENOMEM;
out:
return rc;
}
/**
* ecryptfs_msg_ctx_free_to_alloc
* @msg_ctx: The context to move from the free list to the alloc list
*
* Must be called with ecryptfs_msg_ctx_lists_mux held.
*/
static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
{
list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
msg_ctx->counter = ++ecryptfs_msg_counter;
}
/**
* ecryptfs_msg_ctx_alloc_to_free
* @msg_ctx: The context to move from the alloc list to the free list
*
* Must be called with ecryptfs_msg_ctx_lists_mux held.
*/
void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
{
list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
kfree(msg_ctx->msg);
msg_ctx->msg = NULL;
msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
}
/**
* ecryptfs_find_daemon_by_euid
* @daemon: If return value is zero, points to the desired daemon pointer
*
* Must be called with ecryptfs_daemon_hash_mux held.
*
* Search the hash list for the current effective user id.
*
* Returns zero if the user id exists in the list; non-zero otherwise.
*/
int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
{
int rc;
hlist_for_each_entry(*daemon,
&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
euid_chain) {
if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
rc = 0;
goto out;
}
}
rc = -EINVAL;
out:
return rc;
}
/**
* ecryptfs_spawn_daemon - Create and initialize a new daemon struct
* @daemon: Pointer to set to newly allocated daemon struct
* @file: File used when opening /dev/ecryptfs
*
* Must be called ceremoniously while in possession of
* ecryptfs_sacred_daemon_hash_mux
*
* Returns zero on success; non-zero otherwise
*/
int
ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file)
{
int rc = 0;
(*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
if (!(*daemon)) {
rc = -ENOMEM;
goto out;
}
(*daemon)->file = file;
mutex_init(&(*daemon)->mux);
INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
init_waitqueue_head(&(*daemon)->wait);
(*daemon)->num_queued_msg_ctx = 0;
hlist_add_head(&(*daemon)->euid_chain,
&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]);
out:
return rc;
}
/**
* ecryptfs_exorcise_daemon - Destroy the daemon struct
*
* Must be called ceremoniously while in possession of
* ecryptfs_daemon_hash_mux and the daemon's own mux.
*/
int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
{
struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp;
int rc = 0;
mutex_lock(&daemon->mux);
if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
|| (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
rc = -EBUSY;
mutex_unlock(&daemon->mux);
goto out;
}
list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
&daemon->msg_ctx_out_queue, daemon_out_list) {
list_del(&msg_ctx->daemon_out_list);
daemon->num_queued_msg_ctx--;
printk(KERN_WARNING "%s: Warning: dropping message that is in "
"the out queue of a dying daemon\n", __func__);
ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
}
hlist_del(&daemon->euid_chain);
mutex_unlock(&daemon->mux);
kzfree(daemon);
out:
return rc;
}
/**
* ecryptfs_process_reponse
* @msg: The ecryptfs message received; the caller should sanity check
* msg->data_len and free the memory
* @seq: The sequence number of the message; must match the sequence
* number for the existing message context waiting for this
* response
*
* Processes a response message after sending an operation request to
* userspace. Some other process is awaiting this response. Before
* sending out its first communications, the other process allocated a
* msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
* response message contains this index so that we can copy over the
* response message into the msg_ctx that the process holds a
* reference to. The other process is going to wake up, check to see
* that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
* proceed to read off and process the response message. Returns zero
* upon delivery to desired context element; non-zero upon delivery
* failure or error.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
struct ecryptfs_message *msg, u32 seq)
{
struct ecryptfs_msg_ctx *msg_ctx;
size_t msg_size;
int rc;
if (msg->index >= ecryptfs_message_buf_len) {
rc = -EINVAL;
printk(KERN_ERR "%s: Attempt to reference "
"context buffer at index [%d]; maximum "
"allowable is [%d]\n", __func__, msg->index,
(ecryptfs_message_buf_len - 1));
goto out;
}
msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
mutex_lock(&msg_ctx->mux);
if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
rc = -EINVAL;
printk(KERN_WARNING "%s: Desired context element is not "
"pending a response\n", __func__);
goto unlock;
} else if (msg_ctx->counter != seq) {
rc = -EINVAL;
printk(KERN_WARNING "%s: Invalid message sequence; "
"expected [%d]; received [%d]\n", __func__,
msg_ctx->counter, seq);
goto unlock;
}
msg_size = (sizeof(*msg) + msg->data_len);
msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
if (!msg_ctx->msg) {
rc = -ENOMEM;
goto unlock;
}
msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
wake_up_process(msg_ctx->task);
rc = 0;
unlock:
mutex_unlock(&msg_ctx->mux);
out:
return rc;
}
/**
* ecryptfs_send_message_locked
* @data: The data to send
* @data_len: The length of data
* @msg_ctx: The message context allocated for the send
*
* Must be called with ecryptfs_daemon_hash_mux held.
*
* Returns zero on success; non-zero otherwise
*/
static int
ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
struct ecryptfs_msg_ctx **msg_ctx)
{
struct ecryptfs_daemon *daemon;
int rc;
rc = ecryptfs_find_daemon_by_euid(&daemon);
if (rc) {
rc = -ENOTCONN;
goto out;
}
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
if (rc) {
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
printk(KERN_WARNING "%s: Could not claim a free "
"context element\n", __func__);
goto out;
}
ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
mutex_unlock(&(*msg_ctx)->mux);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
daemon);
if (rc)
printk(KERN_ERR "%s: Error attempting to send message to "
"userspace daemon; rc = [%d]\n", __func__, rc);
out:
return rc;
}
/**
* ecryptfs_send_message
* @data: The data to send
* @data_len: The length of data
* @msg_ctx: The message context allocated for the send
*
* Grabs ecryptfs_daemon_hash_mux.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_send_message(char *data, int data_len,
struct ecryptfs_msg_ctx **msg_ctx)
{
int rc;
mutex_lock(&ecryptfs_daemon_hash_mux);
rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
msg_ctx);
mutex_unlock(&ecryptfs_daemon_hash_mux);
return rc;
}
/**
* ecryptfs_wait_for_response
* @msg_ctx: The context that was assigned when sending a message
* @msg: The incoming message from userspace; not set if rc != 0
*
* Sleeps until awaken by ecryptfs_receive_message or until the amount
* of time exceeds ecryptfs_message_wait_timeout. If zero is
* returned, msg will point to a valid message from userspace; a
* non-zero value is returned upon failure to receive a message or an
* error occurs. Callee must free @msg on success.
*/
int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
struct ecryptfs_message **msg)
{
signed long timeout = ecryptfs_message_wait_timeout * HZ;
int rc = 0;
sleep:
timeout = schedule_timeout_interruptible(timeout);
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
mutex_lock(&msg_ctx->mux);
if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
if (timeout) {
mutex_unlock(&msg_ctx->mux);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
goto sleep;
}
rc = -ENOMSG;
} else {
*msg = msg_ctx->msg;
msg_ctx->msg = NULL;
}
ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
mutex_unlock(&msg_ctx->mux);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
return rc;
}
int __init ecryptfs_init_messaging(void)
{
int i;
int rc = 0;
if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
printk(KERN_WARNING "%s: Specified number of users is "
"too large, defaulting to [%d] users\n", __func__,
ecryptfs_number_of_users);
}
mutex_init(&ecryptfs_daemon_hash_mux);
mutex_lock(&ecryptfs_daemon_hash_mux);
ecryptfs_hash_bits = 1;
while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
ecryptfs_hash_bits++;
ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
* (1 << ecryptfs_hash_bits)),
GFP_KERNEL);
if (!ecryptfs_daemon_hash) {
rc = -ENOMEM;
mutex_unlock(&ecryptfs_daemon_hash_mux);
goto out;
}
for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
mutex_unlock(&ecryptfs_daemon_hash_mux);
ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
* ecryptfs_message_buf_len),
GFP_KERNEL);
if (!ecryptfs_msg_ctx_arr) {
rc = -ENOMEM;
goto out;
}
mutex_init(&ecryptfs_msg_ctx_lists_mux);
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
ecryptfs_msg_counter = 0;
for (i = 0; i < ecryptfs_message_buf_len; i++) {
INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
ecryptfs_msg_ctx_arr[i].index = i;
ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
ecryptfs_msg_ctx_arr[i].counter = 0;
ecryptfs_msg_ctx_arr[i].task = NULL;
ecryptfs_msg_ctx_arr[i].msg = NULL;
list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
&ecryptfs_msg_ctx_free_list);
mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
}
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
rc = ecryptfs_init_ecryptfs_miscdev();
if (rc)
ecryptfs_release_messaging();
out:
return rc;
}
void ecryptfs_release_messaging(void)
{
if (ecryptfs_msg_ctx_arr) {
int i;
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
for (i = 0; i < ecryptfs_message_buf_len; i++) {
mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
kfree(ecryptfs_msg_ctx_arr[i].msg);
mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
}
kfree(ecryptfs_msg_ctx_arr);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
}
if (ecryptfs_daemon_hash) {
struct ecryptfs_daemon *daemon;
struct hlist_node *n;
int i;
mutex_lock(&ecryptfs_daemon_hash_mux);
for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
int rc;
hlist_for_each_entry_safe(daemon, n,
&ecryptfs_daemon_hash[i],
euid_chain) {
rc = ecryptfs_exorcise_daemon(daemon);
if (rc)
printk(KERN_ERR "%s: Error whilst "
"attempting to destroy daemon; "
"rc = [%d]. Dazed and confused, "
"but trying to continue.\n",
__func__, rc);
}
}
kfree(ecryptfs_daemon_hash);
mutex_unlock(&ecryptfs_daemon_hash_mux);
}
ecryptfs_destroy_ecryptfs_miscdev();
return;
}