/**
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 2004-2006 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
* Tyler Hicks <tyhicks@ou.edu>
*
* 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/sched.h>
#include "ecryptfs_kernel.h"
static LIST_HEAD(ecryptfs_msg_ctx_free_list);
static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
static struct mutex ecryptfs_msg_ctx_lists_mux;
static struct hlist_head *ecryptfs_daemon_id_hash;
static struct mutex ecryptfs_daemon_id_hash_mux;
static int ecryptfs_hash_buckets;
#define ecryptfs_uid_hash(uid) \
hash_long((unsigned long)uid, ecryptfs_hash_buckets)
static unsigned int ecryptfs_msg_counter;
static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
/**
* ecryptfs_acquire_free_msg_ctx
* @msg_ctx: The context that was acquired from the free list
*
* Acquires a context element from the free list and locks the mutex
* on the context. Returns zero on success; non-zero on error or upon
* failure to acquire a free context element. Be sure to lock the
* list mutex before calling.
*/
static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
{
struct list_head *p;
int rc;
if (list_empty(&ecryptfs_msg_ctx_free_list)) {
ecryptfs_printk(KERN_WARNING, "The eCryptfs free "
"context list is empty. It may be helpful to "
"specify the ecryptfs_message_buf_len "
"parameter to be greater than the current "
"value of [%d]\n", ecryptfs_message_buf_len);
rc = -ENOMEM;
goto out;
}
list_for_each(p, &ecryptfs_msg_ctx_free_list) {
*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
if (mutex_trylock(&(*msg_ctx)->mux)) {
(*msg_ctx)->task = current;
rc = 0;
goto out;
}
}
rc = -ENOMEM;
out:
return rc;
}
/**
* ecryptfs_msg_ctx_free_to_alloc
* @msg_ctx: The context to move from the free list to the alloc list
*
* Be sure to lock the list mutex and the context mutex before
* calling.
*/
static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
{
list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
msg_ctx->counter = ++ecryptfs_msg_counter;
}
/**
* ecryptfs_msg_ctx_alloc_to_free
* @msg_ctx: The context to move from the alloc list to the free list
*
* Be sure to lock the list mutex and the context mutex before
* calling.
*/
static void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
{
list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
if (msg_ctx->msg)
kfree(msg_ctx->msg);
msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
}
/**
* ecryptfs_find_daemon_id
* @uid: The user id which maps to the desired daemon id
* @id: If return value is zero, points to the desired daemon id
* pointer
*
* Search the hash list for the given user id. Returns zero if the
* user id exists in the list; non-zero otherwise. The daemon id hash
* mutex should be held before calling this function.
*/
static int ecryptfs_find_daemon_id(uid_t uid, struct ecryptfs_daemon_id **id)
{
struct hlist_node *elem;
int rc;
hlist_for_each_entry(*id, elem,
&ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)],
id_chain) {
if ((*id)->uid == uid) {
rc = 0;
goto out;
}
}
rc = -EINVAL;
out:
return rc;
}
static int ecryptfs_send_raw_message(unsigned int transport, u16 msg_type,
pid_t pid)
{
int rc;
switch(transport) {
case ECRYPTFS_TRANSPORT_NETLINK:
rc = ecryptfs_send_netlink(NULL, 0, NULL, msg_type, 0, pid);
break;
case ECRYPTFS_TRANSPORT_CONNECTOR:
case ECRYPTFS_TRANSPORT_RELAYFS:
default:
rc = -ENOSYS;
}
return rc;
}
/**
* ecryptfs_process_helo
* @transport: The underlying transport (netlink, etc.)
* @uid: The user ID owner of the message
* @pid: The process ID for the userspace program that sent the
* message
*
* Adds the uid and pid values to the daemon id hash. If a uid
* already has a daemon pid registered, the daemon will be
* unregistered before the new daemon id is put into the hash list.
* Returns zero after adding a new daemon id to the hash list;
* non-zero otherwise.
*/
int ecryptfs_process_helo(unsigned int transport, uid_t uid, pid_t pid)
{
struct ecryptfs_daemon_id *new_id;
struct ecryptfs_daemon_id *old_id;
int rc;
mutex_lock(&ecryptfs_daemon_id_hash_mux);
new_id = kmalloc(sizeof(*new_id), GFP_KERNEL);
if (!new_id) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Failed to allocate memory; unable "
"to register daemon [%d] for user [%d]\n",
pid, uid);
goto unlock;
}
if (!ecryptfs_find_daemon_id(uid, &old_id)) {
printk(KERN_WARNING "Received request from user [%d] "
"to register daemon [%d]; unregistering daemon "
"[%d]\n", uid, pid, old_id->pid);
hlist_del(&old_id->id_chain);
rc = ecryptfs_send_raw_message(transport, ECRYPTFS_NLMSG_QUIT,
old_id->pid);
if (rc)
printk(KERN_WARNING "Failed to send QUIT "
"message to daemon [%d]; rc = [%d]\n",
old_id->pid, rc);
kfree(old_id);
}
new_id->uid = uid;
new_id->pid = pid;
hlist_add_head(&new_id->id_chain,
&ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)]);
rc = 0;
unlock:
mutex_unlock(&ecryptfs_daemon_id_hash_mux);
return rc;
}
/**
* ecryptfs_process_quit
* @uid: The user ID owner of the message
* @pid: The process ID for the userspace program that sent the
* message
*
* Deletes the corresponding daemon id for the given uid and pid, if
* it is the registered that is requesting the deletion. Returns zero
* after deleting the desired daemon id; non-zero otherwise.
*/
int ecryptfs_process_quit(uid_t uid, pid_t pid)
{
struct ecryptfs_daemon_id *id;
int rc;
mutex_lock(&ecryptfs_daemon_id_hash_mux);
if (ecryptfs_find_daemon_id(uid, &id)) {
rc = -EINVAL;
ecryptfs_printk(KERN_ERR, "Received request from user [%d] to "
"unregister unrecognized daemon [%d]\n", uid,
pid);
goto unlock;
}
if (id->pid != pid) {
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING, "Received request from user [%d] "
"with pid [%d] to unregister daemon [%d]\n",
uid, pid, id->pid);
goto unlock;
}
hlist_del(&id->id_chain);
kfree(id);
rc = 0;
unlock:
mutex_unlock(&ecryptfs_daemon_id_hash_mux);
return rc;
}
/**
* ecryptfs_process_reponse
* @msg: The ecryptfs message received; the caller should sanity check
* msg->data_len
* @pid: The process ID of the userspace application that sent the
* message
* @seq: The sequence number of the message
*
* Processes a response message after sending a operation request to
* userspace. Returns zero upon delivery to desired context element;
* non-zero upon delivery failure or error.
*/
int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t uid,
pid_t pid, u32 seq)
{
struct ecryptfs_daemon_id *id;
struct ecryptfs_msg_ctx *msg_ctx;
int msg_size;
int rc;
if (msg->index >= ecryptfs_message_buf_len) {
rc = -EINVAL;
ecryptfs_printk(KERN_ERR, "Attempt to reference "
"context buffer at index [%d]; maximum "
"allowable is [%d]\n", msg->index,
(ecryptfs_message_buf_len - 1));
goto out;
}
msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
mutex_lock(&msg_ctx->mux);
if (ecryptfs_find_daemon_id(msg_ctx->task->euid, &id)) {
rc = -EBADMSG;
ecryptfs_printk(KERN_WARNING, "User [%d] received a "
"message response from process [%d] but does "
"not have a registered daemon\n",
msg_ctx->task->euid, pid);
goto wake_up;
}
if (msg_ctx->task->euid != uid) {
rc = -EBADMSG;
ecryptfs_printk(KERN_WARNING, "Received message from user "
"[%d]; expected message from user [%d]\n",
uid, msg_ctx->task->euid);
goto unlock;
}
if (id->pid != pid) {
rc = -EBADMSG;
ecryptfs_printk(KERN_ERR, "User [%d] received a "
"message response from an unrecognized "
"process [%d]\n", msg_ctx->task->euid, pid);
goto unlock;
}
if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING, "Desired context element is not "
"pending a response\n");
goto unlock;
} else if (msg_ctx->counter != seq) {
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING, "Invalid message sequence; "
"expected [%d]; received [%d]\n",
msg_ctx->counter, seq);
goto unlock;
}
msg_size = sizeof(*msg) + msg->data_len;
msg_ctx->msg = kmalloc(msg_size, GFP_KERNEL);
if (!msg_ctx->msg) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
goto unlock;
}
memcpy(msg_ctx->msg, msg, msg_size);
msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
rc = 0;
wake_up:
wake_up_process(msg_ctx->task);
unlock:
mutex_unlock(&msg_ctx->mux);
out:
return rc;
}
/**
* ecryptfs_send_message
* @transport: The transport over which to send the message (i.e.,
* netlink)
* @data: The data to send
* @data_len: The length of data
* @msg_ctx: The message context allocated for the send
*/
int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
struct ecryptfs_msg_ctx **msg_ctx)
{
struct ecryptfs_daemon_id *id;
int rc;
mutex_lock(&ecryptfs_daemon_id_hash_mux);
if (ecryptfs_find_daemon_id(current->euid, &id)) {
mutex_unlock(&ecryptfs_daemon_id_hash_mux);
rc = -ENOTCONN;
ecryptfs_printk(KERN_ERR, "User [%d] does not have a daemon "
"registered\n", current->euid);
goto out;
}
mutex_unlock(&ecryptfs_daemon_id_hash_mux);
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
if (rc) {
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
ecryptfs_printk(KERN_WARNING, "Could not claim a free "
"context element\n");
goto out;
}
ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
mutex_unlock(&(*msg_ctx)->mux);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
switch (transport) {
case ECRYPTFS_TRANSPORT_NETLINK:
rc = ecryptfs_send_netlink(data, data_len, *msg_ctx,
ECRYPTFS_NLMSG_REQUEST, 0, id->pid);
break;
case ECRYPTFS_TRANSPORT_CONNECTOR:
case ECRYPTFS_TRANSPORT_RELAYFS:
default:
rc = -ENOSYS;
}
if (rc) {
printk(KERN_ERR "Error attempting to send message to userspace "
"daemon; rc = [%d]\n", rc);
}
out:
return rc;
}
/**
* ecryptfs_wait_for_response
* @msg_ctx: The context that was assigned when sending a message
* @msg: The incoming message from userspace; not set if rc != 0
*
* Sleeps until awaken by ecryptfs_receive_message or until the amount
* of time exceeds ecryptfs_message_wait_timeout. If zero is
* returned, msg will point to a valid message from userspace; a
* non-zero value is returned upon failure to receive a message or an
* error occurs.
*/
int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
struct ecryptfs_message **msg)
{
signed long timeout = ecryptfs_message_wait_timeout * HZ;
int rc = 0;
sleep:
timeout = schedule_timeout_interruptible(timeout);
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
mutex_lock(&msg_ctx->mux);
if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
if (timeout) {
mutex_unlock(&msg_ctx->mux);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
goto sleep;
}
rc = -ENOMSG;
} else {
*msg = msg_ctx->msg;
msg_ctx->msg = NULL;
}
ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
mutex_unlock(&msg_ctx->mux);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
return rc;
}
int ecryptfs_init_messaging(unsigned int transport)
{
int i;
int rc = 0;
if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
ecryptfs_printk(KERN_WARNING, "Specified number of users is "
"too large, defaulting to [%d] users\n",
ecryptfs_number_of_users);
}
mutex_init(&ecryptfs_daemon_id_hash_mux);
mutex_lock(&ecryptfs_daemon_id_hash_mux);
ecryptfs_hash_buckets = 0;
while (ecryptfs_number_of_users >> ++ecryptfs_hash_buckets);
ecryptfs_daemon_id_hash = kmalloc(sizeof(struct hlist_head)
* ecryptfs_hash_buckets, GFP_KERNEL);
if (!ecryptfs_daemon_id_hash) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
goto out;
}
for (i = 0; i < ecryptfs_hash_buckets; i++)
INIT_HLIST_HEAD(&ecryptfs_daemon_id_hash[i]);
mutex_unlock(&ecryptfs_daemon_id_hash_mux);
ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
* ecryptfs_message_buf_len), GFP_KERNEL);
if (!ecryptfs_msg_ctx_arr) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
goto out;
}
mutex_init(&ecryptfs_msg_ctx_lists_mux);
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
ecryptfs_msg_counter = 0;
for (i = 0; i < ecryptfs_message_buf_len; i++) {
INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
ecryptfs_msg_ctx_arr[i].index = i;
ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
ecryptfs_msg_ctx_arr[i].counter = 0;
ecryptfs_msg_ctx_arr[i].task = NULL;
ecryptfs_msg_ctx_arr[i].msg = NULL;
list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
&ecryptfs_msg_ctx_free_list);
mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
}
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
switch(transport) {
case ECRYPTFS_TRANSPORT_NETLINK:
rc = ecryptfs_init_netlink();
if (rc)
ecryptfs_release_messaging(transport);
break;
case ECRYPTFS_TRANSPORT_CONNECTOR:
case ECRYPTFS_TRANSPORT_RELAYFS:
default:
rc = -ENOSYS;
}
out:
return rc;
}
void ecryptfs_release_messaging(unsigned int transport)
{
if (ecryptfs_msg_ctx_arr) {
int i;
mutex_lock(&ecryptfs_msg_ctx_lists_mux);
for (i = 0; i < ecryptfs_message_buf_len; i++) {
mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
if (ecryptfs_msg_ctx_arr[i].msg)
kfree(ecryptfs_msg_ctx_arr[i].msg);
mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
}
kfree(ecryptfs_msg_ctx_arr);
mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
}
if (ecryptfs_daemon_id_hash) {
struct hlist_node *elem;
struct ecryptfs_daemon_id *id;
int i;
mutex_lock(&ecryptfs_daemon_id_hash_mux);
for (i = 0; i < ecryptfs_hash_buckets; i++) {
hlist_for_each_entry(id, elem,
&ecryptfs_daemon_id_hash[i],
id_chain) {
hlist_del(elem);
kfree(id);
}
}
kfree(ecryptfs_daemon_id_hash);
mutex_unlock(&ecryptfs_daemon_id_hash_mux);
}
switch(transport) {
case ECRYPTFS_TRANSPORT_NETLINK:
ecryptfs_release_netlink();
break;
case ECRYPTFS_TRANSPORT_CONNECTOR:
case ECRYPTFS_TRANSPORT_RELAYFS:
default:
break;
}
return;
}
