Fixes an incorrect access mode check when preparing to open a file in the lower

filesystem. This isn't an urgent fix, but it is simple and the check was
 obviously incorrect.
 
 Also fixes a couple important bugs in the eCryptfs miscdev interface. These
 changes are low risk due to the small number of users that use the miscdev
 interface. I was able to keep the changes minimal and I have some cleaner, more
 complete changes queued up for the next merge window that will build on these
 patches.
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Merge tag 'ecryptfs-3.5-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs

Pull eCryptfs fixes from Tyler Hicks:
 "Fixes an incorrect access mode check when preparing to open a file in
  the lower filesystem.  This isn't an urgent fix, but it is simple and
  the check was obviously incorrect.

  Also fixes a couple important bugs in the eCryptfs miscdev interface.
  These changes are low risk due to the small number of users that use
  the miscdev interface.  I was able to keep the changes minimal and I
  have some cleaner, more complete changes queued up for the next merge
  window that will build on these patches."

* tag 'ecryptfs-3.5-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs:
  eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files
  eCryptfs: Fix lockdep warning in miscdev operations
  eCryptfs: Properly check for O_RDONLY flag before doing privileged open

fs/ecryptfs/kthread.c

@@ -149,7 +149,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
 	(*lower_file) = dentry_open(lower_dentry, lower_mnt, flags, cred);
 	if (!IS_ERR(*lower_file))
 		goto out;
-	if (flags & O_RDONLY) {
+	if ((flags & O_ACCMODE) == O_RDONLY) {
 		rc = PTR_ERR((*lower_file));
 		goto out;
 	}

fs/ecryptfs/miscdev.c

@@ -49,7 +49,10 @@ ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
 	mutex_lock(&ecryptfs_daemon_hash_mux);
 	/* TODO: Just use file->private_data? */
 	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
-	BUG_ON(rc || !daemon);
+	if (rc || !daemon) {
+		mutex_unlock(&ecryptfs_daemon_hash_mux);
+		return -EINVAL;
+	}
 	mutex_lock(&daemon->mux);
 	mutex_unlock(&ecryptfs_daemon_hash_mux);
 	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
@@ -122,6 +125,7 @@ ecryptfs_miscdev_open(struct inode *inode, struct file *file)
 		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);
@@ -152,9 +156,9 @@ ecryptfs_miscdev_release(struct inode *inode, struct file *file)
 
 	mutex_lock(&ecryptfs_daemon_hash_mux);
 	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
-	BUG_ON(rc || !daemon);
+	if (rc || !daemon)
+		daemon = file->private_data;
 	mutex_lock(&daemon->mux);
-	BUG_ON(daemon->pid != task_pid(current));
 	BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
 	daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
 	atomic_dec(&ecryptfs_num_miscdev_opens);
@@ -191,31 +195,32 @@ 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)
 {
-	int rc = 0;
+	struct ecryptfs_message *msg;
 
-	mutex_lock(&msg_ctx->mux);
-	msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size),
-			       GFP_KERNEL);
-	if (!msg_ctx->msg) {
-		rc = -ENOMEM;
+	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_ctx->msg) + data_size));
-		goto out_unlock;
+		       (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);
-	mutex_lock(&daemon->mux);
 	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);
-out_unlock:
-	mutex_unlock(&msg_ctx->mux);
-	return rc;
+
+	return 0;
 }
 
 /*
@@ -269,8 +274,16 @@ ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
 	mutex_lock(&ecryptfs_daemon_hash_mux);
 	/* TODO: Just use file->private_data? */
 	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
-	BUG_ON(rc || !daemon);
+	if (rc || !daemon) {
+		mutex_unlock(&ecryptfs_daemon_hash_mux);
+		return -EINVAL;
+	}
 	mutex_lock(&daemon->mux);
+	if (task_pid(current) != daemon->pid) {
+		mutex_unlock(&daemon->mux);
+		mutex_unlock(&ecryptfs_daemon_hash_mux);
+		return -EPERM;
+	}
 	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
 		rc = 0;
 		mutex_unlock(&ecryptfs_daemon_hash_mux);
@@ -307,9 +320,6 @@ check_list:
 		 * message from the queue; try again */
 		goto check_list;
 	}
-	BUG_ON(euid != daemon->euid);
-	BUG_ON(current_user_ns() != daemon->user_ns);
-	BUG_ON(task_pid(current) != daemon->pid);
 	msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
 				   struct ecryptfs_msg_ctx, daemon_out_list);
 	BUG_ON(!msg_ctx);