522 lines
15 KiB
C
522 lines
15 KiB
C
/**
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* eCryptfs: Linux filesystem encryption layer
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*
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* Copyright (C) 2008 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <linux/fs.h>
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#include <linux/hash.h>
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#include <linux/random.h>
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#include <linux/miscdevice.h>
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#include <linux/poll.h>
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#include <linux/slab.h>
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#include <linux/wait.h>
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#include <linux/module.h>
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#include "ecryptfs_kernel.h"
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static atomic_t ecryptfs_num_miscdev_opens;
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/**
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* ecryptfs_miscdev_poll
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* @file: dev file
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* @pt: dev poll table (ignored)
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*
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* Returns the poll mask
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*/
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static unsigned int
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ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
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{
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struct ecryptfs_daemon *daemon = file->private_data;
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unsigned int mask = 0;
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mutex_lock(&daemon->mux);
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if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
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printk(KERN_WARNING "%s: Attempt to poll on zombified "
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"daemon\n", __func__);
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goto out_unlock_daemon;
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}
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if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
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goto out_unlock_daemon;
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if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
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goto out_unlock_daemon;
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daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
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mutex_unlock(&daemon->mux);
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poll_wait(file, &daemon->wait, pt);
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mutex_lock(&daemon->mux);
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if (!list_empty(&daemon->msg_ctx_out_queue))
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mask |= POLLIN | POLLRDNORM;
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out_unlock_daemon:
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daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
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mutex_unlock(&daemon->mux);
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return mask;
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}
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/**
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* ecryptfs_miscdev_open
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* @inode: inode of miscdev handle (ignored)
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* @file: file for miscdev handle
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int
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ecryptfs_miscdev_open(struct inode *inode, struct file *file)
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{
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struct ecryptfs_daemon *daemon = NULL;
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int rc;
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mutex_lock(&ecryptfs_daemon_hash_mux);
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rc = try_module_get(THIS_MODULE);
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if (rc == 0) {
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rc = -EIO;
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printk(KERN_ERR "%s: Error attempting to increment module use "
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"count; rc = [%d]\n", __func__, rc);
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goto out_unlock_daemon_list;
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}
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rc = ecryptfs_find_daemon_by_euid(&daemon);
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if (!rc) {
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rc = -EINVAL;
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goto out_unlock_daemon_list;
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}
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rc = ecryptfs_spawn_daemon(&daemon, file);
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if (rc) {
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printk(KERN_ERR "%s: Error attempting to spawn daemon; "
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"rc = [%d]\n", __func__, rc);
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goto out_module_put_unlock_daemon_list;
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}
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mutex_lock(&daemon->mux);
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if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
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rc = -EBUSY;
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goto out_unlock_daemon;
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}
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daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN;
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file->private_data = daemon;
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atomic_inc(&ecryptfs_num_miscdev_opens);
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out_unlock_daemon:
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mutex_unlock(&daemon->mux);
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out_module_put_unlock_daemon_list:
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if (rc)
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module_put(THIS_MODULE);
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out_unlock_daemon_list:
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mutex_unlock(&ecryptfs_daemon_hash_mux);
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return rc;
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}
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/**
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* ecryptfs_miscdev_release
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* @inode: inode of fs/ecryptfs/euid handle (ignored)
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* @file: file for fs/ecryptfs/euid handle
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*
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* This keeps the daemon registered until the daemon sends another
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* ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int
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ecryptfs_miscdev_release(struct inode *inode, struct file *file)
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{
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struct ecryptfs_daemon *daemon = file->private_data;
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int rc;
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mutex_lock(&daemon->mux);
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BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
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daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
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atomic_dec(&ecryptfs_num_miscdev_opens);
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mutex_unlock(&daemon->mux);
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mutex_lock(&ecryptfs_daemon_hash_mux);
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rc = ecryptfs_exorcise_daemon(daemon);
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mutex_unlock(&ecryptfs_daemon_hash_mux);
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if (rc) {
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printk(KERN_CRIT "%s: Fatal error whilst attempting to "
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"shut down daemon; rc = [%d]. Please report this "
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"bug.\n", __func__, rc);
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BUG();
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}
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module_put(THIS_MODULE);
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return rc;
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}
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/**
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* ecryptfs_send_miscdev
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* @data: Data to send to daemon; may be NULL
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* @data_size: Amount of data to send to daemon
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* @msg_ctx: Message context, which is used to handle the reply. If
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* this is NULL, then we do not expect a reply.
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* @msg_type: Type of message
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* @msg_flags: Flags for message
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* @daemon: eCryptfs daemon object
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*
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* Add msg_ctx to queue and then, if it exists, notify the blocked
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* miscdevess about the data being available. Must be called with
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* ecryptfs_daemon_hash_mux held.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_send_miscdev(char *data, size_t data_size,
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struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
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u16 msg_flags, struct ecryptfs_daemon *daemon)
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{
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struct ecryptfs_message *msg;
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msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
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if (!msg) {
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printk(KERN_ERR "%s: Out of memory whilst attempting "
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"to kmalloc(%zd, GFP_KERNEL)\n", __func__,
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(sizeof(*msg) + data_size));
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return -ENOMEM;
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}
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mutex_lock(&msg_ctx->mux);
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msg_ctx->msg = msg;
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msg_ctx->msg->index = msg_ctx->index;
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msg_ctx->msg->data_len = data_size;
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msg_ctx->type = msg_type;
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memcpy(msg_ctx->msg->data, data, data_size);
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msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
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list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
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mutex_unlock(&msg_ctx->mux);
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mutex_lock(&daemon->mux);
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daemon->num_queued_msg_ctx++;
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wake_up_interruptible(&daemon->wait);
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mutex_unlock(&daemon->mux);
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return 0;
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}
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/*
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* miscdevfs packet format:
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* Octet 0: Type
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* Octets 1-4: network byte order msg_ctx->counter
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* Octets 5-N0: Size of struct ecryptfs_message to follow
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* Octets N0-N1: struct ecryptfs_message (including data)
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*
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* Octets 5-N1 not written if the packet type does not include a message
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*/
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#define PKT_TYPE_SIZE 1
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#define PKT_CTR_SIZE 4
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#define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
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#define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
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+ ECRYPTFS_MIN_PKT_LEN_SIZE)
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/* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
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#define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
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+ ECRYPTFS_MAX_PKT_LEN_SIZE \
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+ sizeof(struct ecryptfs_message) \
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+ 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
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#define PKT_TYPE_OFFSET 0
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#define PKT_CTR_OFFSET PKT_TYPE_SIZE
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#define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
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/**
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* ecryptfs_miscdev_read - format and send message from queue
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* @file: miscdevfs handle
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* @buf: User buffer into which to copy the next message on the daemon queue
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* @count: Amount of space available in @buf
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* @ppos: Offset in file (ignored)
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*
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* Pulls the most recent message from the daemon queue, formats it for
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* being sent via a miscdevfs handle, and copies it into @buf
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*
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* Returns the number of bytes copied into the user buffer
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*/
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static ssize_t
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ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
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loff_t *ppos)
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{
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struct ecryptfs_daemon *daemon = file->private_data;
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struct ecryptfs_msg_ctx *msg_ctx;
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size_t packet_length_size;
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char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
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size_t i;
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size_t total_length;
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int rc;
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mutex_lock(&daemon->mux);
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if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
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rc = 0;
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printk(KERN_WARNING "%s: Attempt to read from zombified "
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"daemon\n", __func__);
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goto out_unlock_daemon;
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}
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if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
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rc = 0;
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goto out_unlock_daemon;
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}
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/* This daemon will not go away so long as this flag is set */
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daemon->flags |= ECRYPTFS_DAEMON_IN_READ;
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check_list:
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if (list_empty(&daemon->msg_ctx_out_queue)) {
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mutex_unlock(&daemon->mux);
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rc = wait_event_interruptible(
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daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
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mutex_lock(&daemon->mux);
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if (rc < 0) {
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rc = 0;
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goto out_unlock_daemon;
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}
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}
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if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
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rc = 0;
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goto out_unlock_daemon;
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}
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if (list_empty(&daemon->msg_ctx_out_queue)) {
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/* Something else jumped in since the
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* wait_event_interruptable() and removed the
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* message from the queue; try again */
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goto check_list;
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}
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msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
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struct ecryptfs_msg_ctx, daemon_out_list);
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BUG_ON(!msg_ctx);
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mutex_lock(&msg_ctx->mux);
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if (msg_ctx->msg) {
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rc = ecryptfs_write_packet_length(packet_length,
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msg_ctx->msg_size,
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&packet_length_size);
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if (rc) {
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rc = 0;
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printk(KERN_WARNING "%s: Error writing packet length; "
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"rc = [%d]\n", __func__, rc);
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goto out_unlock_msg_ctx;
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}
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} else {
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packet_length_size = 0;
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msg_ctx->msg_size = 0;
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}
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total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
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+ msg_ctx->msg_size);
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if (count < total_length) {
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rc = 0;
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printk(KERN_WARNING "%s: Only given user buffer of "
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"size [%zd], but we need [%zd] to read the "
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"pending message\n", __func__, count, total_length);
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goto out_unlock_msg_ctx;
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}
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rc = -EFAULT;
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if (put_user(msg_ctx->type, buf))
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goto out_unlock_msg_ctx;
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if (put_user(cpu_to_be32(msg_ctx->counter),
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(__be32 __user *)(&buf[PKT_CTR_OFFSET])))
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goto out_unlock_msg_ctx;
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i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
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if (msg_ctx->msg) {
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if (copy_to_user(&buf[i], packet_length, packet_length_size))
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goto out_unlock_msg_ctx;
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i += packet_length_size;
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if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
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goto out_unlock_msg_ctx;
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i += msg_ctx->msg_size;
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}
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rc = i;
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list_del(&msg_ctx->daemon_out_list);
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kfree(msg_ctx->msg);
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msg_ctx->msg = NULL;
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/* We do not expect a reply from the userspace daemon for any
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* message type other than ECRYPTFS_MSG_REQUEST */
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if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
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ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
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out_unlock_msg_ctx:
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mutex_unlock(&msg_ctx->mux);
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out_unlock_daemon:
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daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
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mutex_unlock(&daemon->mux);
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return rc;
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}
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/**
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* ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
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* @data: Bytes comprising struct ecryptfs_message
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* @data_size: sizeof(struct ecryptfs_message) + data len
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* @seq: Sequence number for miscdev response packet
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int ecryptfs_miscdev_response(struct ecryptfs_daemon *daemon, char *data,
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size_t data_size, u32 seq)
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{
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struct ecryptfs_message *msg = (struct ecryptfs_message *)data;
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int rc;
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if ((sizeof(*msg) + msg->data_len) != data_size) {
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printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
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"[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
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(sizeof(*msg) + msg->data_len), data_size);
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rc = -EINVAL;
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goto out;
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}
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rc = ecryptfs_process_response(daemon, msg, seq);
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if (rc)
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printk(KERN_ERR
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"Error processing response message; rc = [%d]\n", rc);
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out:
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return rc;
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}
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/**
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* ecryptfs_miscdev_write - handle write to daemon miscdev handle
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* @file: File for misc dev handle
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* @buf: Buffer containing user data
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* @count: Amount of data in @buf
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* @ppos: Pointer to offset in file (ignored)
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*
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* Returns the number of bytes read from @buf
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*/
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static ssize_t
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ecryptfs_miscdev_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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__be32 counter_nbo;
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u32 seq;
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size_t packet_size, packet_size_length;
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char *data;
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unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
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ssize_t rc;
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if (count == 0) {
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return 0;
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} else if (count == MIN_NON_MSG_PKT_SIZE) {
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/* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
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goto memdup;
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} else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
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printk(KERN_WARNING "%s: Acceptable packet size range is "
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"[%d-%zu], but amount of data written is [%zu].",
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__func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
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return -EINVAL;
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}
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if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
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sizeof(packet_size_peek))) {
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printk(KERN_WARNING "%s: Error while inspecting packet size\n",
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__func__);
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return -EFAULT;
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}
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rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
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&packet_size_length);
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if (rc) {
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printk(KERN_WARNING "%s: Error parsing packet length; "
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"rc = [%zd]\n", __func__, rc);
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return rc;
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}
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if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
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!= count) {
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printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
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packet_size);
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return -EINVAL;
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}
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memdup:
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data = memdup_user(buf, count);
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if (IS_ERR(data)) {
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printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
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__func__, PTR_ERR(data));
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return PTR_ERR(data);
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}
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switch (data[PKT_TYPE_OFFSET]) {
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case ECRYPTFS_MSG_RESPONSE:
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if (count < (MIN_MSG_PKT_SIZE
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+ sizeof(struct ecryptfs_message))) {
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printk(KERN_WARNING "%s: Minimum acceptable packet "
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"size is [%zd], but amount of data written is "
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"only [%zd]. Discarding response packet.\n",
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__func__,
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(MIN_MSG_PKT_SIZE
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+ sizeof(struct ecryptfs_message)), count);
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rc = -EINVAL;
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goto out_free;
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}
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memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
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seq = be32_to_cpu(counter_nbo);
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rc = ecryptfs_miscdev_response(file->private_data,
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&data[PKT_LEN_OFFSET + packet_size_length],
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packet_size, seq);
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if (rc) {
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printk(KERN_WARNING "%s: Failed to deliver miscdev "
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"response to requesting operation; rc = [%zd]\n",
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__func__, rc);
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goto out_free;
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}
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break;
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case ECRYPTFS_MSG_HELO:
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case ECRYPTFS_MSG_QUIT:
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break;
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default:
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ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
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"message of unrecognized type [%d]\n",
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data[0]);
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rc = -EINVAL;
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goto out_free;
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}
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rc = count;
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out_free:
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kfree(data);
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return rc;
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}
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static const struct file_operations ecryptfs_miscdev_fops = {
|
|
.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);
|
|
}
|