/** * 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; uid_t euid = current_euid(); int rc; mutex_lock(&ecryptfs_daemon_hash_mux); /* TODO: Just use file->private_data? */ rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); 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; uid_t euid = current_euid(); 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, euid, current_user_ns()); if (rc || !daemon) { rc = ecryptfs_spawn_daemon(&daemon, euid, current_user_ns(), task_pid(current)); 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 != task_pid(current)) { rc = -EINVAL; printk(KERN_ERR "%s: pid [0x%p] has registered with euid [%d], " "but pid [0x%p] has attempted to open the handle " "instead\n", __func__, daemon->pid, daemon->euid, task_pid(current)); 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 [0x%p] 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; uid_t euid = current_euid(); int rc; mutex_lock(&ecryptfs_daemon_hash_mux); rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); BUG_ON(rc || !daemon); mutex_lock(&daemon->mux); BUG_ON(daemon->pid != task_pid(current)); 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); 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(%zd, GFP_KERNEL)\n", __func__, (sizeof(*msg_ctx->msg) + data_size)); goto out_unlock; } 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); 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 ssize_t 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; char packet_length[3]; size_t i; size_t total_length; uid_t euid = current_euid(); int rc; mutex_lock(&ecryptfs_daemon_hash_mux); /* TODO: Just use file->private_data? */ rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); BUG_ON(rc || !daemon); mutex_lock(&daemon->mux); if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { rc = 0; mutex_unlock(&ecryptfs_daemon_hash_mux); 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; mutex_unlock(&ecryptfs_daemon_hash_mux); 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(euid != daemon->euid); BUG_ON(current_user_ns() != daemon->user_ns); BUG_ON(task_pid(current) != 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; } 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 + 1))) goto out_unlock_msg_ctx; i = 5; 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 * @euid: Effective user id of miscdevess sending the miscdev response * @user_ns: The namespace in which @euid applies * @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, struct user_namespace *user_ns, struct pid *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, user_ns, 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) { __be32 counter_nbo; u32 seq; size_t packet_size, packet_size_length, i; ssize_t sz = 0; char *data; uid_t euid = current_euid(); int rc; if (count == 0) goto out; data = memdup_user(buf, count); if (IS_ERR(data)) { printk(KERN_ERR "%s: memdup_user returned error [%ld]\n", __func__, PTR_ERR(data)); goto out; } 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(&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, euid, current_user_ns(), task_pid(current), 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: case ECRYPTFS_MSG_QUIT: 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); 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); }