- 根目录:
- fs
- ecryptfs
- miscdev.c
/**
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 2008 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
*
* 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.
*/
#include <linux/fs.h>
#include <linux/hash.h>
#include <linux/random.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/module.h>
#include "ecryptfs_kernel.h"
static atomic_t ecryptfs_num_miscdev_opens;
/**
* ecryptfs_miscdev_poll
* @file: dev file
* @pt: dev poll table (ignored)
*
* Returns the poll mask
*/
static unsigned int
ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
{
struct ecryptfs_daemon *daemon = file->private_data;
unsigned int mask = 0;
mutex_lock(&daemon->mux);
if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
printk(KERN_WARNING "%s: Attempt to poll on zombified "
"daemon\n", __func__);
goto out_unlock_daemon;
}
if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
goto out_unlock_daemon;
if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
goto out_unlock_daemon;
daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
mutex_unlock(&daemon->mux);
poll_wait(file, &daemon->wait, pt);
mutex_lock(&daemon->mux);
if (!list_empty(&daemon->msg_ctx_out_queue))
mask |= POLLIN | POLLRDNORM;
out_unlock_daemon:
daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
mutex_unlock(&daemon->mux);
return mask;
}
/**
* ecryptfs_miscdev_open
* @inode: inode of miscdev handle (ignored)
* @file: file for miscdev handle
*
* Returns zero on success; non-zero otherwise
*/
static int
ecryptfs_miscdev_open(struct inode *inode, struct file *file)
{
struct ecryptfs_daemon *daemon = NULL;
int rc;
mutex_lock(&ecryptfs_daemon_hash_mux);
rc = ecryptfs_find_daemon_by_euid(&daemon);
if (!rc) {
rc = -EINVAL;
goto out_unlock_daemon_list;
}
rc = ecryptfs_spawn_daemon(&daemon, file);
if (rc) {
printk(KERN_ERR "%s: Error attempting to spawn daemon; "
"rc = [%d]\n", __func__, rc);
goto out_unlock_daemon_list;
}
mutex_lock(&daemon->mux);
if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
rc = -EBUSY;
goto out_unlock_daemon;
}
daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN;
file->private_data = daemon;
atomic_inc(&ecryptfs_num_miscdev_opens);
out_unlock_daemon:
mutex_unlock(&daemon->mux);
out_unlock_daemon_list:
mutex_unlock(&ecryptfs_daemon_hash_mux);
return rc;
}
/**
* ecryptfs_miscdev_release
* @inode: inode of fs/ecryptfs/euid handle (ignored)
* @file: file for fs/ecryptfs/euid handle
*
* This keeps the daemon registered until the daemon sends another
* ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
*
* Returns zero on success; non-zero otherwise
*/
static int
ecryptfs_miscdev_release(struct inode *inode, struct file *file)
{
struct ecryptfs_daemon *daemon = file->private_data;
int rc;
mutex_lock(&daemon->mux);
BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
atomic_dec(&ecryptfs_num_miscdev_opens);
mutex_unlock(&daemon->mux);
mutex_lock(&ecryptfs_daemon_hash_mux);
rc = ecryptfs_exorcise_daemon(daemon);
mutex_unlock(&ecryptfs_daemon_hash_mux);
if (rc) {
printk(KERN_CRIT "%s: Fatal error whilst attempting to "
"shut down daemon; rc = [%d]. Please report this "
"bug.\n", __func__, rc);
BUG();
}
return rc;
}
/**
* ecryptfs_send_miscdev
* @data: Data to send to daemon; may be NULL
* @data_size: Amount of data to send to daemon
* @msg_ctx: Message context, which is used to handle the reply. If
* this is NULL, then we do not expect a reply.
* @msg_type: Type of message
* @msg_flags: Flags for message
* @daemon: eCryptfs daemon object
*
* Add msg_ctx to queue and then, if it exists, notify the blocked
* miscdevess about the data being available. Must be called with
* ecryptfs_daemon_hash_mux held.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_send_miscdev(char *data, size_t data_size,
struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
u16 msg_flags, struct ecryptfs_daemon *daemon)
{
struct ecryptfs_message *msg;
msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
if (!msg) {
printk(KERN_ERR "%s: Out of memory whilst attempting "
"to kmalloc(%zd, GFP_KERNEL)\n", __func__,
(sizeof(*msg) + data_size));
return -ENOMEM;
}
mutex_lock(&msg_ctx->mux);
msg_ctx->msg = msg;
msg_ctx->msg->index = msg_ctx->index;
msg_ctx->msg->data_len = data_size;
msg_ctx->type = msg_type;
memcpy(msg_ctx->msg->data, data, data_size);
msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
mutex_unlock(&msg_ctx->mux);
mutex_lock(&daemon->mux);
daemon->num_queued_msg_ctx++;
wake_up_interruptible(&daemon->wait);
mutex_unlock(&daemon->mux);
return 0;
}
/*
* miscdevfs packet format:
* Octet 0: Type
* Octets 1-4: network byte order msg_ctx->counter
* Octets 5-N0: Size of struct ecryptfs_message to follow
* Octets N0-N1: struct ecryptfs_message (including data)
*
* Octets 5-N1 not written if the packet type does not include a message
*/
#define PKT_TYPE_SIZE 1
#define PKT_CTR_SIZE 4
#define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
#define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
+ ECRYPTFS_MIN_PKT_LEN_SIZE)
/* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
#define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
+ ECRYPTFS_MAX_PKT_LEN_SIZE \
+ sizeof(struct ecryptfs_message) \
+ 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
#define PKT_TYPE_OFFSET 0
#define PKT_CTR_OFFSET PKT_TYPE_SIZE
#define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
/**
* ecryptfs_miscdev_read - format and send message from queue
* @file: miscdevfs handle
* @buf: User buffer into which to copy the next message on the daemon queue
* @count: Amount of space available in @buf
* @ppos: Offset in file (ignored)
*
* Pulls the most recent message from the daemon queue, formats it for
* being sent via a miscdevfs handle, and copies it into @buf
*
* Returns the number of bytes copied into the user buffer
*/
static ssize_t
ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
{
struct ecryptfs_daemon *daemon = file->private_data;
struct ecryptfs_msg_ctx *msg_ctx;
size_t packet_length_size;
char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
size_t i;
size_t total_length;
int rc;
mutex_lock(&daemon->mux);
if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
rc = 0;
printk(KERN_WARNING "%s: Attempt to read from zombified "
"daemon\n", __func__);
goto out_unlock_daemon;
}
if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
rc = 0;
goto out_unlock_daemon;
}
/* This daemon will not go away so long as this flag is set */
daemon->flags |= ECRYPTFS_DAEMON_IN_READ;
check_list:
if (list_empty(&daemon->msg_ctx_out_queue)) {
mutex_unlock(&daemon->mux);
rc = wait_event_interruptible(
daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
mutex_lock(&daemon->mux);
if (rc < 0) {
rc = 0;
goto out_unlock_daemon;
}
}
if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
rc = 0;
goto out_unlock_daemon;
}
if (list_empty(&daemon->msg_ctx_out_queue)) {
/* Something else jumped in since the
* wait_event_interruptable() and removed the
* message from the queue; try again */
goto check_list;
}
msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
struct ecryptfs_msg_ctx, daemon_out_list);
BUG_ON(!msg_ctx);
mutex_lock(&msg_ctx->mux);
if (msg_ctx->msg) {
rc = ecryptfs_write_packet_length(packet_length,
msg_ctx->msg_size,
&packet_length_size);
if (rc) {
rc = 0;
printk(KERN_WARNING "%s: Error writing packet length; "
"rc = [%d]\n", __func__, rc);
goto out_unlock_msg_ctx;
}
} else {
packet_length_size = 0;
msg_ctx->msg_size = 0;
}
total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
+ msg_ctx->msg_size);
if (count < total_length) {
rc = 0;
printk(KERN_WARNING "%s: Only given user buffer of "
"size [%zd], but we need [%zd] to read the "
"pending message\n", __func__, count, total_length);
goto out_unlock_msg_ctx;
}
rc = -EFAULT;
if (put_user(msg_ctx->type, buf))
goto out_unlock_msg_ctx;
if (put_user(cpu_to_be32(msg_ctx->counter),
(__be32 __user *)(&buf[PKT_CTR_OFFSET])))
goto out_unlock_msg_ctx;
i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
if (msg_ctx->msg) {
if (copy_to_user(&buf[i], packet_length, packet_length_size))
goto out_unlock_msg_ctx;
i += packet_length_size;
if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
goto out_unlock_msg_ctx;
i += msg_ctx->msg_size;
}
rc = i;
list_del(&msg_ctx->daemon_out_list);
kfree(msg_ctx->msg);
msg_ctx->msg = NULL;
/* We do not expect a reply from the userspace daemon for any
* message type other than ECRYPTFS_MSG_REQUEST */
if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
out_unlock_msg_ctx:
mutex_unlock(&msg_ctx->mux);
out_unlock_daemon:
daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
mutex_unlock(&daemon->mux);
return rc;
}
/**
* ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
* @data: Bytes comprising struct ecryptfs_message
* @data_size: sizeof(struct ecryptfs_message) + data len
* @seq: Sequence number for miscdev response packet
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_miscdev_response(struct ecryptfs_daemon *daemon, char *data,
size_t data_size, u32 seq)
{
struct ecryptfs_message *msg = (struct ecryptfs_message *)data;
int rc;
if ((sizeof(*msg) + msg->data_len) != data_size) {
printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
"[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
(sizeof(*msg) + msg->data_len), data_size);
rc = -EINVAL;
goto out;
}
rc = ecryptfs_process_response(daemon, msg, seq);
if (rc)
printk(KERN_ERR
"Error processing response message; rc = [%d]\n", rc);
out:
return rc;
}
/**
* ecryptfs_miscdev_write - handle write to daemon miscdev handle
* @file: File for misc dev handle
* @buf: Buffer containing user data
* @count: Amount of data in @buf
* @ppos: Pointer to offset in file (ignored)
*
* Returns the number of bytes read from @buf
*/
static ssize_t
ecryptfs_miscdev_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
__be32 counter_nbo;
u32 seq;
size_t packet_size, packet_size_length;
char *data;
unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
ssize_t rc;
if (count == 0) {
return 0;
} else if (count == MIN_NON_MSG_PKT_SIZE) {
/* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
goto memdup;
} else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
printk(KERN_WARNING "%s: Acceptable packet size range is "
"[%d-%zu], but amount of data written is [%zu].",
__func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
return -EINVAL;
}
if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
sizeof(packet_size_peek))) {
printk(KERN_WARNING "%s: Error while inspecting packet size\n",
__func__);
return -EFAULT;
}
rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
&packet_size_length);
if (rc) {
printk(KERN_WARNING "%s: Error parsing packet length; "
"rc = [%zd]\n", __func__, rc);
return rc;
}
if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
!= count) {
printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
packet_size);
return -EINVAL;
}
memdup:
data = memdup_user(buf, count);
if (IS_ERR(data)) {
printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
__func__, PTR_ERR(data));
return PTR_ERR(data);
}
switch (data[PKT_TYPE_OFFSET]) {
case ECRYPTFS_MSG_RESPONSE:
if (count < (MIN_MSG_PKT_SIZE
+ sizeof(struct ecryptfs_message))) {
printk(KERN_WARNING "%s: Minimum acceptable packet "
"size is [%zd], but amount of data written is "
"only [%zd]. Discarding response packet.\n",
__func__,
(MIN_MSG_PKT_SIZE
+ sizeof(struct ecryptfs_message)), count);
rc = -EINVAL;
goto out_free;
}
memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
seq = be32_to_cpu(counter_nbo);
rc = ecryptfs_miscdev_response(file->private_data,
&data[PKT_LEN_OFFSET + packet_size_length],
packet_size, seq);
if (rc) {
printk(KERN_WARNING "%s: Failed to deliver miscdev "
"response to requesting operation; rc = [%zd]\n",
__func__, rc);
goto out_free;
}
break;
case ECRYPTFS_MSG_HELO:
case ECRYPTFS_MSG_QUIT:
break;
default:
ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
"message of unrecognized type [%d]\n",
data[0]);
rc = -EINVAL;
goto out_free;
}
rc = count;
out_free:
kfree(data);
return rc;
}
static const struct file_operations ecryptfs_miscdev_fops = {
.owner = THIS_MODULE,
.open = ecryptfs_miscdev_open,
.poll = ecryptfs_miscdev_poll,
.read = ecryptfs_miscdev_read,
.write = ecryptfs_miscdev_write,
.release = ecryptfs_miscdev_release,
.llseek = noop_llseek,
};
static struct miscdevice ecryptfs_miscdev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "ecryptfs",
.fops = &ecryptfs_miscdev_fops
};
/**
* ecryptfs_init_ecryptfs_miscdev
*
* Messages sent to the userspace daemon from the kernel are placed on
* a queue associated with the daemon. The next read against the
* miscdev handle by that daemon will return the oldest message placed
* on the message queue for the daemon.
*
* Returns zero on success; non-zero otherwise
*/
int __init ecryptfs_init_ecryptfs_miscdev(void)
{
int rc;
atomic_set(&ecryptfs_num_miscdev_opens, 0);
rc = misc_register(&ecryptfs_miscdev);
if (rc)
printk(KERN_ERR "%s: Failed to register miscellaneous device "
"for communications with userspace daemons; rc = [%d]\n",
__func__, rc);
return rc;
}
/**
* ecryptfs_destroy_ecryptfs_miscdev
*
* All of the daemons must be exorcised prior to calling this
* function.
*/
void ecryptfs_destroy_ecryptfs_miscdev(void)
{
BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0);
misc_deregister(&ecryptfs_miscdev);
}