Initial import

1 files changed, 468 insertions, 0 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
new file mode 100644
index 000000000..286f10b03
--- /dev/null
+++ b/fs/ecryptfs/messaging.c
@@ -0,0 +1,468 @@
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 2004-2008 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 <linux/slab.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_hash;
+struct mutex ecryptfs_daemon_hash_mux;
+static int ecryptfs_hash_bits;
+#define ecryptfs_current_euid_hash(uid) \
+	hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)
+
+static u32 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.  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)
+{
+	struct list_head *p;
+	int rc;
+
+	if (list_empty(&ecryptfs_msg_ctx_free_list)) {
+		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;
+	}
+	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
+ *
+ * Must be called with ecryptfs_msg_ctx_lists_mux held.
+ */
+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
+ *
+ * Must be called with ecryptfs_msg_ctx_lists_mux held.
+ */
+void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
+{
+	list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
+	kfree(msg_ctx->msg);
+	msg_ctx->msg = NULL;
+	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
+}
+
+/**
+ * ecryptfs_find_daemon_by_euid
+ * @daemon: If return value is zero, points to the desired daemon pointer
+ *
+ * Must be called with ecryptfs_daemon_hash_mux held.
+ *
+ * Search the hash list for the current effective user id.
+ *
+ * Returns zero if the user id exists in the list; non-zero otherwise.
+ */
+int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
+{
+	int rc;
+
+	hlist_for_each_entry(*daemon,
+			    &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
+			    euid_chain) {
+		if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
+			rc = 0;
+			goto out;
+		}
+	}
+	rc = -EINVAL;
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
+ * @daemon: Pointer to set to newly allocated daemon struct
+ * @file: File used when opening /dev/ecryptfs
+ *
+ * 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, struct file *file)
+{
+	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)->file = file;
+	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_current_euid_hash()]);
+out:
+	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;
+		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);
+	mutex_unlock(&daemon->mux);
+	kzfree(daemon);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_process_reponse
+ * @msg: The ecryptfs message received; the caller should sanity check
+ *       msg->data_len and free the memory
+ * @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.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
+			      struct ecryptfs_message *msg, u32 seq)
+{
+	struct ecryptfs_msg_ctx *msg_ctx;
+	size_t msg_size;
+	int rc;
+
+	if (msg->index >= ecryptfs_message_buf_len) {
+		rc = -EINVAL;
+		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 (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
+		rc = -EINVAL;
+		printk(KERN_WARNING "%s: Desired context element is not "
+		       "pending a response\n", __func__);
+		goto unlock;
+	} else if (msg_ctx->counter != seq) {
+		rc = -EINVAL;
+		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_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
+	if (!msg_ctx->msg) {
+		rc = -ENOMEM;
+		printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
+		       "GFP_KERNEL memory\n", __func__, msg_size);
+		goto unlock;
+	}
+	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
+	wake_up_process(msg_ctx->task);
+	rc = 0;
+unlock:
+	mutex_unlock(&msg_ctx->mux);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_send_message_locked
+ * @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
+ */
+static int
+ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
+			     struct ecryptfs_msg_ctx **msg_ctx)
+{
+	struct ecryptfs_daemon *daemon;
+	int rc;
+
+	rc = ecryptfs_find_daemon_by_euid(&daemon);
+	if (rc) {
+		rc = -ENOTCONN;
+		goto out;
+	}
+	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
+	rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
+	if (rc) {
+		mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+		printk(KERN_WARNING "%s: Could not claim a free "
+		       "context element\n", __func__);
+		goto out;
+	}
+	ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
+	mutex_unlock(&(*msg_ctx)->mux);
+	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+	rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
+				   daemon);
+	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
+ * @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(char *data, int data_len,
+			  struct ecryptfs_msg_ctx **msg_ctx)
+{
+	int rc;
+
+	mutex_lock(&ecryptfs_daemon_hash_mux);
+	rc = ecryptfs_send_message_locked(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
+ *
+ * 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. Callee must free @msg on success.
+ */
+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 __init ecryptfs_init_messaging(void)
+{
+	int i;
+	int rc = 0;
+
+	if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
+		ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_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_hash_mux);
+	mutex_lock(&ecryptfs_daemon_hash_mux);
+	ecryptfs_hash_bits = 1;
+	while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
+		ecryptfs_hash_bits++;
+	ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
+					* (1 << ecryptfs_hash_bits)),
+				       GFP_KERNEL);
+	if (!ecryptfs_daemon_hash) {
+		rc = -ENOMEM;
+		printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
+		mutex_unlock(&ecryptfs_daemon_hash_mux);
+		goto out;
+	}
+	for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
+		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);
+	if (!ecryptfs_msg_ctx_arr) {
+		rc = -ENOMEM;
+		printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
+		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);
+		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;
+		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);
+	rc = ecryptfs_init_ecryptfs_miscdev();
+	if (rc)
+		ecryptfs_release_messaging();
+out:
+	return rc;
+}
+
+void ecryptfs_release_messaging(void)
+{
+	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);
+			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_hash) {
+		struct ecryptfs_daemon *daemon;
+		int i;
+
+		mutex_lock(&ecryptfs_daemon_hash_mux);
+		for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
+			int rc;
+
+			hlist_for_each_entry(daemon,
+					     &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_hash);
+		mutex_unlock(&ecryptfs_daemon_hash_mux);
+	}
+	ecryptfs_destroy_ecryptfs_miscdev();
+	return;
+}