diff options
Diffstat (limited to 'fs/ecryptfs/miscdev.c')
| -rw-r--r-- | fs/ecryptfs/miscdev.c | 511 |
1 files changed, 511 insertions, 0 deletions
diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c new file mode 100644 index 000000000..e4141f257 --- /dev/null +++ b/fs/ecryptfs/miscdev.c @@ -0,0 +1,511 @@ +/** + * 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); +} |