1 files changed, 360 insertions, 164 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index 9cc2aec..1b5c200 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>
  *
@@ -20,19 +20,21 @@
  * 02111-1307, USA.
  */
 #include <linux/sched.h>
+#include <linux/user_namespace.h>
+#include <linux/nsproxy.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 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 +42,10 @@ 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 +53,11 @@ 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 +78,7 @@ 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 +91,39 @@ 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
+ * @user_ns: The namespace in which @euid applies
+ * @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 user_namespace *user_ns)
 {
 	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 && (*daemon)->user_ns == user_ns) {
 			rc = 0;
 			goto out;
 		}
@@ -128,181 +133,325 @@ 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
+ * @user_ns: The namespace in which @euid applies
+ * @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,
+		      struct user_namespace *user_ns, struct pid *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)->user_ns = get_user_ns(user_ns);
+	(*daemon)->pid = get_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
+ * @user_ns: The namespace in which @euid applies
  * @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,
+			  struct user_namespace *user_ns, struct pid *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, user_ns);
+	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);
+		       "to register daemon [0x%p]; unregistering daemon "
+		       "[0x%p]\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);
+			       "message to daemon [0x%p]; rc = [%d]\n",
+			       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, user_ns, pid);
+	if (rc)
+		printk(KERN_ERR "%s: The gods are displeased with this attempt "
+		       "to create a new daemon object for euid [%d]; pid "
+		       "[0x%p]; 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 "
+		       "[0x%p], 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);
+	if (daemon->pid)
+		put_pid(daemon->pid);
+	if (daemon->user_ns)
+		put_user_ns(daemon->user_ns);
+	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
+ * @user_ns: The namespace in which @euid applies
  * @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, struct user_namespace *user_ns,
+			  struct pid *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)) {
+	mutex_lock(&ecryptfs_daemon_hash_mux);
+	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, user_ns);
+	if (rc || !daemon) {
 		rc = -EINVAL;
-		ecryptfs_printk(KERN_ERR, "Received request from user [%d] to "
-				"unregister unrecognized daemon [%d]\n", uid,
-				pid);
-		goto unlock;
+		printk(KERN_ERR "Received request from user [%d] to "
+		       "unregister unrecognized daemon [0x%p]\n", euid, pid);
+		goto out_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);
+	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,
-			      pid_t pid, u32 seq)
+int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
+			      struct user_namespace *user_ns, struct pid *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;
+	struct nsproxy *nsproxy;
+	struct user_namespace *current_user_ns;
 	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);
+	rcu_read_lock();
+	nsproxy = task_nsproxy(msg_ctx->task);
+	if (nsproxy == NULL) {
 		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_ERR "%s: Receiving process is a zombie. Dropping "
+		       "message.\n", __func__);
+		rcu_read_unlock();
+		mutex_unlock(&ecryptfs_daemon_hash_mux);
 		goto wake_up;
 	}
-	if (msg_ctx->task->euid != uid) {
+	current_user_ns = nsproxy->user_ns;
+	rc = ecryptfs_find_daemon_by_euid(&daemon, msg_ctx->task->euid,
+					  current_user_ns);
+	rcu_read_unlock();
+	mutex_unlock(&ecryptfs_daemon_hash_mux);
+	if (rc) {
+		rc = -EBADMSG;
+		printk(KERN_WARNING "%s: User [%d] received a "
+		       "message response from process [0x%p] but does "
+		       "not have a registered daemon\n", __func__,
+		       msg_ctx->task->euid, pid);
+		goto wake_up;
+	}
+	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 (current_user_ns != user_ns) {
 		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_WARNING "%s: Received message from user_ns "
+		       "[0x%p]; expected message from user_ns [0x%p]\n",
+		       __func__, user_ns, nsproxy->user_ns);
+		goto unlock;
+	}
+	if (daemon->pid != pid) {
+		rc = -EBADMSG;
+		printk(KERN_ERR "%s: User [%d] sent a message response "
+		       "from an unrecognized process [0x%p]\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 +466,38 @@ 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,
+					  current->nsproxy->user_ns);
+	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 +505,50 @@ 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 +557,7 @@ 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 +593,32 @@ 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 +626,7 @@ 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 +645,11 @@ 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 +674,37 @@ 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: