diff options
| -rw-r--r-- | fs/ecryptfs/miscdev.c | 580 |
1 files changed, 580 insertions, 0 deletions
diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c new file mode 100644 index 0000000..72dfec4 --- /dev/null +++ b/fs/ecryptfs/miscdev.c @@ -0,0 +1,580 @@ +/** + * 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/wait.h> +#include <linux/module.h> +#include "ecryptfs_kernel.h" + +static atomic_t ecryptfs_num_miscdev_opens; + +/** + * ecryptfs_miscdev_poll + * @file: dev file (ignored) + * @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; + unsigned int mask = 0; + int rc; + + mutex_lock(&ecryptfs_daemon_hash_mux); + /* TODO: Just use file->private_data? */ + rc = ecryptfs_find_daemon_by_euid(&daemon, current->euid); + BUG_ON(rc || !daemon); + mutex_lock(&daemon->mux); + mutex_unlock(&ecryptfs_daemon_hash_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 (ignored) + * + * 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 = try_module_get(THIS_MODULE); + if (rc == 0) { + rc = -EIO; + printk(KERN_ERR "%s: Error attempting to increment module use " + "count; rc = [%d]\n", __func__, rc); + goto out_unlock_daemon_list; + } + rc = ecryptfs_find_daemon_by_euid(&daemon, current->euid); + if (rc || !daemon) { + rc = ecryptfs_spawn_daemon(&daemon, current->euid, + current->pid); + if (rc) { + printk(KERN_ERR "%s: Error attempting to spawn daemon; " + "rc = [%d]\n", __func__, rc); + goto out_module_put_unlock_daemon_list; + } + } + mutex_lock(&daemon->mux); + if (daemon->pid != current->pid) { + rc = -EINVAL; + printk(KERN_ERR "%s: pid [%d] has registered with euid [%d], " + "but pid [%d] has attempted to open the handle " + "instead\n", __func__, daemon->pid, daemon->euid, + current->pid); + goto out_unlock_daemon; + } + if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) { + rc = -EBUSY; + printk(KERN_ERR "%s: Miscellaneous device handle may only be " + "opened once per daemon; pid [%d] already has this " + "handle open\n", __func__, daemon->pid); + goto out_unlock_daemon; + } + daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN; + atomic_inc(&ecryptfs_num_miscdev_opens); +out_unlock_daemon: + mutex_unlock(&daemon->mux); +out_module_put_unlock_daemon_list: + if (rc) + module_put(THIS_MODULE); +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 (ignored) + * + * 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 = NULL; + int rc; + + mutex_lock(&ecryptfs_daemon_hash_mux); + rc = ecryptfs_find_daemon_by_euid(&daemon, current->euid); + BUG_ON(rc || !daemon); + mutex_lock(&daemon->mux); + BUG_ON(daemon->pid != current->pid); + BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN)); + daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN; + atomic_dec(&ecryptfs_num_miscdev_opens); + mutex_unlock(&daemon->mux); + rc = ecryptfs_exorcise_daemon(daemon); + if (rc) { + printk(KERN_CRIT "%s: Fatal error whilst attempting to " + "shut down daemon; rc = [%d]. Please report this " + "bug.\n", __func__, rc); + BUG(); + } + module_put(THIS_MODULE); + mutex_unlock(&ecryptfs_daemon_hash_mux); + 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) +{ + int rc = 0; + + mutex_lock(&msg_ctx->mux); + if (data) { + msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size), + GFP_KERNEL); + if (!msg_ctx->msg) { + rc = -ENOMEM; + printk(KERN_ERR "%s: Out of memory whilst attempting " + "to kmalloc(%d, GFP_KERNEL)\n", __func__, + (sizeof(*msg_ctx->msg) + data_size)); + goto out_unlock; + } + } else + msg_ctx->msg = NULL; + msg_ctx->msg->index = msg_ctx->index; + msg_ctx->msg->data_len = data_size; + msg_ctx->type = msg_type; + if (data) { + memcpy(msg_ctx->msg->data, data, data_size); + msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size); + } else + msg_ctx->msg_size = 0; + mutex_lock(&daemon->mux); + list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue); + daemon->num_queued_msg_ctx++; + wake_up_interruptible(&daemon->wait); + mutex_unlock(&daemon->mux); +out_unlock: + mutex_unlock(&msg_ctx->mux); + return rc; +} + +/** + * ecryptfs_miscdev_read - format and send message from queue + * @file: fs/ecryptfs/euid miscdevfs handle (ignored) + * @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 int +ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count, + loff_t *ppos) +{ + struct ecryptfs_daemon *daemon; + struct ecryptfs_msg_ctx *msg_ctx; + size_t packet_length_size; + u32 counter_nbo; + char packet_length[3]; + size_t i; + size_t total_length; + int rc; + + mutex_lock(&ecryptfs_daemon_hash_mux); + /* TODO: Just use file->private_data? */ + rc = ecryptfs_find_daemon_by_euid(&daemon, current->euid); + BUG_ON(rc || !daemon); + 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; + mutex_unlock(&ecryptfs_daemon_hash_mux); +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; + } + BUG_ON(current->euid != daemon->euid); + BUG_ON(current->pid != daemon->pid); + 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; + } + /* 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 */ + total_length = (1 + 4 + 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; + } + i = 0; + buf[i++] = msg_ctx->type; + counter_nbo = cpu_to_be32(msg_ctx->counter); + memcpy(&buf[i], (char *)&counter_nbo, 4); + i += 4; + if (msg_ctx->msg) { + memcpy(&buf[i], packet_length, packet_length_size); + i += packet_length_size; + rc = copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size); + if (rc) { + printk(KERN_ERR "%s: copy_to_user returned error " + "[%d]\n", __func__, rc); + 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_helo + * @euid: effective user id of miscdevess sending helo packet + * @pid: miscdevess id of miscdevess sending helo packet + * + * Returns zero on success; non-zero otherwise + */ +static int ecryptfs_miscdev_helo(uid_t uid, pid_t pid) +{ + int rc; + + rc = ecryptfs_process_helo(ECRYPTFS_TRANSPORT_MISCDEV, uid, pid); + if (rc) + printk(KERN_WARNING "Error processing HELO; rc = [%d]\n", rc); + return rc; +} + +/** + * ecryptfs_miscdev_quit + * @euid: effective user id of miscdevess sending quit packet + * @pid: miscdevess id of miscdevess sending quit packet + * + * Returns zero on success; non-zero otherwise + */ +static int ecryptfs_miscdev_quit(uid_t euid, pid_t pid) +{ + int rc; + + rc = ecryptfs_process_quit(euid, pid); + if (rc) + printk(KERN_WARNING + "Error processing QUIT message; rc = [%d]\n", rc); + 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 + * @euid: Effective user id of miscdevess sending the miscdev response + * @pid: Miscdevess id of miscdevess sending the miscdev response + * @seq: Sequence number for miscdev response packet + * + * Returns zero on success; non-zero otherwise + */ +static int ecryptfs_miscdev_response(char *data, size_t data_size, + uid_t euid, pid_t pid, 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(msg, euid, pid, 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 (ignored) + * @buf: Buffer containing user data + * @count: Amount of data in @buf + * @ppos: Pointer to offset in file (ignored) + * + * miscdevfs packet format: + * Octet 0: Type + * Octets 1-4: network byte order msg_ctx->counter (0's for non-response) + * Octets 5-N0: Size of struct ecryptfs_message to follow + * Octets N0-N1: struct ecryptfs_message (including data) + * + * 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) +{ + u32 counter_nbo, seq; + size_t packet_size, packet_size_length, i; + ssize_t sz = 0; + char *data; + int rc; + + if (count == 0) + goto out; + data = kmalloc(count, GFP_KERNEL); + if (!data) { + printk(KERN_ERR "%s: Out of memory whilst attempting to " + "kmalloc([%Zd], GFP_KERNEL)\n", __func__, count); + goto out; + } + rc = copy_from_user(data, buf, count); + if (rc) { + printk(KERN_ERR "%s: copy_from_user returned error [%d]\n", + __func__, rc); + goto out_free; + } + sz = count; + i = 0; + switch (data[i++]) { + case ECRYPTFS_MSG_RESPONSE: + if (count < (1 + 4 + 1 + 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__, + (1 + 4 + 1 + sizeof(struct ecryptfs_message)), + count); + goto out_free; + } + memcpy((char *)&counter_nbo, &data[i], 4); + seq = be32_to_cpu(counter_nbo); + i += 4; + rc = ecryptfs_parse_packet_length(&data[i], &packet_size, + &packet_size_length); + if (rc) { + printk(KERN_WARNING "%s: Error parsing packet length; " + "rc = [%d]\n", __func__, rc); + goto out_free; + } + i += packet_size_length; + if ((1 + 4 + packet_size_length + packet_size) != count) { + printk(KERN_WARNING "%s: (1 + packet_size_length([%Zd])" + " + packet_size([%Zd]))([%Zd]) != " + "count([%Zd]). Invalid packet format.\n", + __func__, packet_size_length, packet_size, + (1 + packet_size_length + packet_size), count); + goto out_free; + } + rc = ecryptfs_miscdev_response(&data[i], packet_size, + current->euid, + current->pid, seq); + if (rc) + printk(KERN_WARNING "%s: Failed to deliver miscdev " + "response to requesting operation; rc = [%d]\n", + __func__, rc); + break; + case ECRYPTFS_MSG_HELO: + rc = ecryptfs_miscdev_helo(current->euid, current->pid); + if (rc) { + printk(KERN_ERR "%s: Error attempting to process " + "helo from pid [%d]; rc = [%d]\n", __func__, + current->pid, rc); + goto out_free; + } + break; + case ECRYPTFS_MSG_QUIT: + rc = ecryptfs_miscdev_quit(current->euid, current->pid); + if (rc) { + printk(KERN_ERR "%s: Error attempting to process " + "quit from pid [%d]; rc = [%d]\n", __func__, + current->pid, rc); + goto out_free; + } + break; + default: + ecryptfs_printk(KERN_WARNING, "Dropping miscdev " + "message of unrecognized type [%d]\n", + data[0]); + break; + } +out_free: + kfree(data); +out: + return sz; +} + + +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, +}; + +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 ecryptfs_init_ecryptfs_miscdev(void) +{ + int rc; + + atomic_set(&ecryptfs_num_miscdev_opens, 0); + mutex_lock(&ecryptfs_daemon_hash_mux); + 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); + mutex_unlock(&ecryptfs_daemon_hash_mux); + 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); +} |
