eCryptfs: integrate eCryptfs device handle into the module.

Update the versioning information.  Make the message types generic.  Add an
outgoing message queue to the daemon struct.  Make the functions to parse
and write the packet lengths available to the rest of the module.  Add
functions to create and destroy the daemon structs.  Clean up some of the
comments and make the code a little more consistent with itself.

[akpm@linux-foundation.org: printk fixes]
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 318 insertions, 161 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index 9cc2aec27b0d..c6038bd60897 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -1,7 +1,7 @@
 /**
  * eCryptfs: Linux filesystem encryption layer
  *
- * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Copyright (C) 2004-2008 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
  *              Tyler Hicks <tyhicks@ou.edu>
  *
@@ -26,13 +26,13 @@ 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 struct hlist_head *ecryptfs_daemon_hash;
+struct mutex ecryptfs_daemon_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 u32 ecryptfs_msg_counter;
 static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
 
 /**
@@ -40,9 +40,10 @@ static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
  * @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.
+ * on the context.  Sets the msg_ctx task to current.  Returns zero on
+ * success; non-zero on error or upon failure to acquire a free
+ * context element.  Must be called with ecryptfs_msg_ctx_lists_mux
+ * held.
  */
 static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
 {
@@ -50,11 +51,11 @@ static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
         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);
+                printk(KERN_WARNING "%s: 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", __func__, ecryptfs_message_buf_len);
                 rc = -ENOMEM;
                 goto out;
         }
@@ -75,8 +76,7 @@ out:
  * 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.
+ * Must be called with ecryptfs_msg_ctx_lists_mux held.
  */
 static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
 {
@@ -89,36 +89,37 @@ static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
  * 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.
+ * Must be called with ecryptfs_msg_ctx_lists_mux held.
  */
-static void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
+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->msg = NULL;
         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
+ * ecryptfs_find_daemon_by_euid
+ * @euid: The effective user id which maps to the desired daemon id
+ * @daemon: If return value is zero, points to the desired daemon 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.
+ * Must be called with ecryptfs_daemon_hash_mux held.
+ *
+ * Search the hash list for the given user id.
+ *
+ * Returns zero if the user id exists in the list; non-zero otherwise.
  */
-static int ecryptfs_find_daemon_id(uid_t uid, struct ecryptfs_daemon_id **id)
+int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon, uid_t euid)
 {
         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) {
+        hlist_for_each_entry(*daemon, elem,
+                             &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)],
+                             euid_chain) {
+                if ((*daemon)->euid == euid) {
                         rc = 0;
                         goto out;
                 }
@@ -128,181 +129,291 @@ out:
         return rc;
 }
 
-static int ecryptfs_send_raw_message(unsigned int transport, u16 msg_type,
-                                     pid_t pid)
+static int
+ecryptfs_send_message_locked(unsigned int transport, char *data, int data_len,
+                             u8 msg_type, struct ecryptfs_msg_ctx **msg_ctx);
+
+/**
+ * ecryptfs_send_raw_message
+ * @transport: Transport type
+ * @msg_type: Message type
+ * @daemon: Daemon struct for recipient of message
+ *
+ * A raw message is one that does not include an ecryptfs_message
+ * struct. It simply has a type.
+ *
+ * Must be called with ecryptfs_daemon_hash_mux held.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_send_raw_message(unsigned int transport, u8 msg_type,
+                                     struct ecryptfs_daemon *daemon)
 {
+        struct ecryptfs_msg_ctx *msg_ctx;
         int rc;
 
         switch(transport) {
         case ECRYPTFS_TRANSPORT_NETLINK:
-                rc = ecryptfs_send_netlink(NULL, 0, NULL, msg_type, 0, pid);
+                rc = ecryptfs_send_netlink(NULL, 0, NULL, msg_type, 0,
+                                           daemon->pid);
+                break;
+        case ECRYPTFS_TRANSPORT_MISCDEV:
+                rc = ecryptfs_send_message_locked(transport, NULL, 0, msg_type,
+                                                  &msg_ctx);
+                if (rc) {
+                        printk(KERN_ERR "%s: Error whilst attempting to send "
+                               "message via procfs; rc = [%d]\n", __func__, rc);
+                        goto out;
+                }
+                /* Raw messages are logically context-free (e.g., no
+                 * reply is expected), so we set the state of the
+                 * ecryptfs_msg_ctx object to indicate that it should
+                 * be freed as soon as the transport sends out the message. */
+                mutex_lock(&msg_ctx->mux);
+                msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_NO_REPLY;
+                mutex_unlock(&msg_ctx->mux);
                 break;
         case ECRYPTFS_TRANSPORT_CONNECTOR:
         case ECRYPTFS_TRANSPORT_RELAYFS:
         default:
                 rc = -ENOSYS;
         }
+out:
+        return rc;
+}
+
+/**
+ * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
+ * @daemon: Pointer to set to newly allocated daemon struct
+ * @euid: Effective user id for the daemon
+ * @pid: Process id for the daemon
+ *
+ * Must be called ceremoniously while in possession of
+ * ecryptfs_sacred_daemon_hash_mux
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int
+ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, uid_t euid, pid_t pid)
+{
+        int rc = 0;
+
+        (*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
+        if (!(*daemon)) {
+                rc = -ENOMEM;
+                printk(KERN_ERR "%s: Failed to allocate [%Zd] bytes of "
+                       "GFP_KERNEL memory\n", __func__, sizeof(**daemon));
+                goto out;
+        }
+        (*daemon)->euid = euid;
+        (*daemon)->pid = pid;
+        (*daemon)->task = current;
+        mutex_init(&(*daemon)->mux);
+        INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
+        init_waitqueue_head(&(*daemon)->wait);
+        (*daemon)->num_queued_msg_ctx = 0;
+        hlist_add_head(&(*daemon)->euid_chain,
+                       &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)]);
+out:
         return rc;
 }
 
 /**
  * ecryptfs_process_helo
  * @transport: The underlying transport (netlink, etc.)
- * @uid: The user ID owner of the message
+ * @euid: 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
+ * Adds the euid and pid values to the daemon euid hash.  If an euid
  * 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;
+ * unregistered before the new daemon is put into the hash list.
+ * Returns zero after adding a new daemon to the hash list;
  * non-zero otherwise.
  */
-int ecryptfs_process_helo(unsigned int transport, uid_t uid, pid_t pid)
+int ecryptfs_process_helo(unsigned int transport, uid_t euid, pid_t pid)
 {
-        struct ecryptfs_daemon_id *new_id;
-        struct ecryptfs_daemon_id *old_id;
+        struct ecryptfs_daemon *new_daemon;
+        struct ecryptfs_daemon *old_daemon;
         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)) {
+        mutex_lock(&ecryptfs_daemon_hash_mux);
+        rc = ecryptfs_find_daemon_by_euid(&old_daemon, euid);
+        if (rc != 0) {
                 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);
+                       "[%d]\n", euid, pid, old_daemon->pid);
+                rc = ecryptfs_send_raw_message(transport, ECRYPTFS_MSG_QUIT,
+                                               old_daemon);
                 if (rc)
                         printk(KERN_WARNING "Failed to send QUIT "
                                "message to daemon [%d]; rc = [%d]\n",
-                               old_id->pid, rc);
-                kfree(old_id);
+                               old_daemon->pid, rc);
+                hlist_del(&old_daemon->euid_chain);
+                kfree(old_daemon);
         }
-        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);
+        rc = ecryptfs_spawn_daemon(&new_daemon, euid, pid);
+        if (rc)
+                printk(KERN_ERR "%s: The gods are displeased with this attempt "
+                       "to create a new daemon object for euid [%d]; pid [%d]; "
+                       "rc = [%d]\n", __func__, euid, pid, rc);
+        mutex_unlock(&ecryptfs_daemon_hash_mux);
+        return rc;
+}
+
+/**
+ * ecryptfs_exorcise_daemon - Destroy the daemon struct
+ *
+ * Must be called ceremoniously while in possession of
+ * ecryptfs_daemon_hash_mux and the daemon's own mux.
+ */
+int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
+{
+        struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp;
+        int rc = 0;
+
+        mutex_lock(&daemon->mux);
+        if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
+            || (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
+                rc = -EBUSY;
+                printk(KERN_WARNING "%s: Attempt to destroy daemon with pid "
+                       "[%d], but it is in the midst of a read or a poll\n",
+                       __func__, daemon->pid);
+                mutex_unlock(&daemon->mux);
+                goto out;
+        }
+        list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
+                                 &daemon->msg_ctx_out_queue, daemon_out_list) {
+                list_del(&msg_ctx->daemon_out_list);
+                daemon->num_queued_msg_ctx--;
+                printk(KERN_WARNING "%s: Warning: dropping message that is in "
+                       "the out queue of a dying daemon\n", __func__);
+                ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
+        }
+        hlist_del(&daemon->euid_chain);
+        if (daemon->task)
+                wake_up_process(daemon->task);
+        mutex_unlock(&daemon->mux);
+        memset(daemon, 0, sizeof(*daemon));
+        kfree(daemon);
+out:
         return rc;
 }
 
 /**
  * ecryptfs_process_quit
- * @uid: The user ID owner of the message
+ * @euid: 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
+ * Deletes the corresponding daemon for the given euid and pid, if
  * it is the registered that is requesting the deletion. Returns zero
- * after deleting the desired daemon id; non-zero otherwise.
+ * after deleting the desired daemon; non-zero otherwise.
  */
-int ecryptfs_process_quit(uid_t uid, pid_t pid)
+int ecryptfs_process_quit(uid_t euid, pid_t pid)
 {
-        struct ecryptfs_daemon_id *id;
+        struct ecryptfs_daemon *daemon;
         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) {
+        mutex_lock(&ecryptfs_daemon_hash_mux);
+        rc = ecryptfs_find_daemon_by_euid(&daemon, euid);
+        if (rc || !daemon) {
                 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;
+                printk(KERN_ERR "Received request from user [%d] to "
+                       "unregister unrecognized daemon [%d]\n", euid, pid);
+                goto out_unlock;
         }
-        hlist_del(&id->id_chain);
-        kfree(id);
-        rc = 0;
-unlock:
-        mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+        rc = ecryptfs_exorcise_daemon(daemon);
+out_unlock:
+        mutex_unlock(&ecryptfs_daemon_hash_mux);
         return rc;
 }
 
 /**
  * ecryptfs_process_reponse
  * @msg: The ecryptfs message received; the caller should sanity check
- *       msg->data_len
+ *       msg->data_len and free the memory
  * @pid: The process ID of the userspace application that sent the
  *       message
- * @seq: The sequence number of the message
+ * @seq: The sequence number of the message; must match the sequence
+ *       number for the existing message context waiting for this
+ *       response
+ *
+ * Processes a response message after sending an operation request to
+ * userspace. Some other process is awaiting this response. Before
+ * sending out its first communications, the other process allocated a
+ * msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
+ * response message contains this index so that we can copy over the
+ * response message into the msg_ctx that the process holds a
+ * reference to. The other process is going to wake up, check to see
+ * that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
+ * proceed to read off and process the response message. Returns zero
+ * upon delivery to desired context element; non-zero upon delivery
+ * failure or error.
  *
- * 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.
+ * Returns zero on success; non-zero otherwise
  */
-int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t uid,
+int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
                               pid_t pid, u32 seq)
 {
-        struct ecryptfs_daemon_id *id;
+        struct ecryptfs_daemon *daemon;
         struct ecryptfs_msg_ctx *msg_ctx;
-        int msg_size;
+        size_t 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));
+                printk(KERN_ERR "%s: Attempt to reference "
+                       "context buffer at index [%d]; maximum "
+                       "allowable is [%d]\n", __func__, 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)) {
+        mutex_lock(&ecryptfs_daemon_hash_mux);
+        rc = ecryptfs_find_daemon_by_euid(&daemon, msg_ctx->task->euid);
+        mutex_unlock(&ecryptfs_daemon_hash_mux);
+        if (rc) {
                 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);
+                printk(KERN_WARNING "%s: User [%d] received a "
+                       "message response from process [%d] but does "
+                       "not have a registered daemon\n", __func__,
+                       msg_ctx->task->euid, pid);
                 goto wake_up;
         }
-        if (msg_ctx->task->euid != uid) {
+        if (msg_ctx->task->euid != euid) {
                 rc = -EBADMSG;
-                ecryptfs_printk(KERN_WARNING, "Received message from user "
-                                "[%d]; expected message from user [%d]\n",
-                                uid, msg_ctx->task->euid);
+                printk(KERN_WARNING "%s: Received message from user "
+                       "[%d]; expected message from user [%d]\n", __func__,
+                       euid, msg_ctx->task->euid);
                 goto unlock;
         }
-        if (id->pid != pid) {
+        if (daemon->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);
+                printk(KERN_ERR "%s: User [%d] sent a message response "
+                       "from an unrecognized process [%d]\n",
+                       __func__, 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");
+                printk(KERN_WARNING "%s: Desired context element is not "
+                       "pending a response\n", __func__);
                 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);
+                printk(KERN_WARNING "%s: Invalid message sequence; "
+                       "expected [%d]; received [%d]\n", __func__,
+                       msg_ctx->counter, seq);
                 goto unlock;
         }
-        msg_size = sizeof(*msg) + msg->data_len;
+        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");
+                printk(KERN_ERR "%s: Failed to allocate [%Zd] bytes of "
+                       "GFP_KERNEL memory\n", __func__, msg_size);
                 goto unlock;
         }
         memcpy(msg_ctx->msg, msg, msg_size);
@@ -317,34 +428,37 @@ out:
 }
 
 /**
- * ecryptfs_send_message
+ * ecryptfs_send_message_locked
  * @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
+ *
+ * Must be called with ecryptfs_daemon_hash_mux held.
+ *
+ * Returns zero on success; non-zero otherwise
  */
-int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
-                          struct ecryptfs_msg_ctx **msg_ctx)
+static int
+ecryptfs_send_message_locked(unsigned int transport, char *data, int data_len,
+                             u8 msg_type, struct ecryptfs_msg_ctx **msg_ctx)
 {
-        struct ecryptfs_daemon_id *id;
+        struct ecryptfs_daemon *daemon;
         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 = ecryptfs_find_daemon_by_euid(&daemon, current->euid);
+        if (rc || !daemon) {
                 rc = -ENOTCONN;
-                ecryptfs_printk(KERN_ERR, "User [%d] does not have a daemon "
-                                "registered\n", current->euid);
+                printk(KERN_ERR "%s: User [%d] does not have a daemon "
+                       "registered\n", __func__, 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");
+                printk(KERN_WARNING "%s: Could not claim a free "
+                       "context element\n", __func__);
                 goto out;
         }
         ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
@@ -352,23 +466,50 @@ int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
         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);
+                rc = ecryptfs_send_netlink(data, data_len, *msg_ctx, msg_type,
+                                           0, daemon->pid);
+                break;
+        case ECRYPTFS_TRANSPORT_MISCDEV:
+                rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type,
+                                           0, daemon);
                 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);
-        }
+        if (rc)
+                printk(KERN_ERR "%s: Error attempting to send message to "
+                       "userspace daemon; rc = [%d]\n", __func__, rc);
 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
+ *
+ * Grabs ecryptfs_daemon_hash_mux.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
+                          struct ecryptfs_msg_ctx **msg_ctx)
+{
+        int rc;
+
+        mutex_lock(&ecryptfs_daemon_hash_mux);
+        rc = ecryptfs_send_message_locked(transport, data, data_len,
+                                          ECRYPTFS_MSG_REQUEST, msg_ctx);
+        mutex_unlock(&ecryptfs_daemon_hash_mux);
+        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
@@ -377,7 +518,7 @@ out:
  * 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.
+ * error occurs. Callee must free @msg on success.
  */
 int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
                                struct ecryptfs_message **msg)
@@ -413,32 +554,32 @@ int ecryptfs_init_messaging(unsigned int transport)
 
         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);
+                printk(KERN_WARNING "%s: Specified number of users is "
+                       "too large, defaulting to [%d] users\n", __func__,
+                       ecryptfs_number_of_users);
         }
-        mutex_init(&ecryptfs_daemon_id_hash_mux);
-        mutex_lock(&ecryptfs_daemon_id_hash_mux);
+        mutex_init(&ecryptfs_daemon_hash_mux);
+        mutex_lock(&ecryptfs_daemon_hash_mux);
         ecryptfs_hash_buckets = 1;
         while (ecryptfs_number_of_users >> ecryptfs_hash_buckets)
                 ecryptfs_hash_buckets++;
-        ecryptfs_daemon_id_hash = kmalloc(sizeof(struct hlist_head)
-                                          * ecryptfs_hash_buckets, GFP_KERNEL);
-        if (!ecryptfs_daemon_id_hash) {
+        ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
+                                        * ecryptfs_hash_buckets), GFP_KERNEL);
+        if (!ecryptfs_daemon_hash) {
                 rc = -ENOMEM;
-                ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
-                mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+                printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
+                mutex_unlock(&ecryptfs_daemon_hash_mux);
                 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);
-
+                INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
+        mutex_unlock(&ecryptfs_daemon_hash_mux);
         ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
-                                      * ecryptfs_message_buf_len), GFP_KERNEL);
+                                        * ecryptfs_message_buf_len),
+                                       GFP_KERNEL);
         if (!ecryptfs_msg_ctx_arr) {
                 rc = -ENOMEM;
-                ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
+                printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
                 goto out;
         }
         mutex_init(&ecryptfs_msg_ctx_lists_mux);
@@ -446,6 +587,7 @@ int ecryptfs_init_messaging(unsigned int transport)
         ecryptfs_msg_counter = 0;
         for (i = 0; i < ecryptfs_message_buf_len; i++) {
                 INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
+                INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
                 mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
                 mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
                 ecryptfs_msg_ctx_arr[i].index = i;
@@ -464,6 +606,11 @@ int ecryptfs_init_messaging(unsigned int transport)
                 if (rc)
                         ecryptfs_release_messaging(transport);
                 break;
+        case ECRYPTFS_TRANSPORT_MISCDEV:
+                rc = ecryptfs_init_ecryptfs_miscdev();
+                if (rc)
+                        ecryptfs_release_messaging(transport);
+                break;
         case ECRYPTFS_TRANSPORT_CONNECTOR:
         case ECRYPTFS_TRANSPORT_RELAYFS:
         default:
@@ -488,27 +635,37 @@ void ecryptfs_release_messaging(unsigned int transport)
                 kfree(ecryptfs_msg_ctx_arr);
                 mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
         }
-        if (ecryptfs_daemon_id_hash) {
+        if (ecryptfs_daemon_hash) {
                 struct hlist_node *elem;
-                struct ecryptfs_daemon_id *id;
+                struct ecryptfs_daemon *daemon;
                 int i;
 
-                mutex_lock(&ecryptfs_daemon_id_hash_mux);
+                mutex_lock(&ecryptfs_daemon_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);
+                        int rc;
+
+                        hlist_for_each_entry(daemon, elem,
+                                             &ecryptfs_daemon_hash[i],
+                                             euid_chain) {
+                                rc = ecryptfs_exorcise_daemon(daemon);
+                                if (rc)
+                                        printk(KERN_ERR "%s: Error whilst "
+                                               "attempting to destroy daemon; "
+                                               "rc = [%d]. Dazed and confused, "
+                                               "but trying to continue.\n",
+                                               __func__, rc);
                         }
                 }
-                kfree(ecryptfs_daemon_id_hash);
-                mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+                kfree(ecryptfs_daemon_hash);
+                mutex_unlock(&ecryptfs_daemon_hash_mux);
         }
         switch(transport) {
         case ECRYPTFS_TRANSPORT_NETLINK:
                 ecryptfs_release_netlink();
                 break;
+        case ECRYPTFS_TRANSPORT_MISCDEV:
+                ecryptfs_destroy_ecryptfs_miscdev();
+                break;
         case ECRYPTFS_TRANSPORT_CONNECTOR:
         case ECRYPTFS_TRANSPORT_RELAYFS:
         default: