/*
   * security/tomoyo/mount.c
   *

   * Copyright (C) 2005-2011  NTT DATA CORPORATION

   */
  
  #include <linux/slab.h>
  #include "common.h"

  /* String table for special mount operations. */
  static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
  	[TOMOYO_MOUNT_BIND]            = "--bind",
  	[TOMOYO_MOUNT_MOVE]            = "--move",
  	[TOMOYO_MOUNT_REMOUNT]         = "--remount",
  	[TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
  	[TOMOYO_MOUNT_MAKE_PRIVATE]    = "--make-private",
  	[TOMOYO_MOUNT_MAKE_SLAVE]      = "--make-slave",
  	[TOMOYO_MOUNT_MAKE_SHARED]     = "--make-shared",
  };

  
  /**

   * tomoyo_audit_mount_log - Audit mount log.
   *
   * @r: Pointer to "struct tomoyo_request_info".
   *
   * Returns 0 on success, negative value otherwise.
   */
  static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
  {

  	return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX
  ",

  				 r->param.mount.dev->name,

  				 r->param.mount.dir->name,
  				 r->param.mount.type->name,
  				 r->param.mount.flags);

  }

  /**
   * tomoyo_check_mount_acl - Check permission for path path path number operation.
   *
   * @r:   Pointer to "struct tomoyo_request_info".
   * @ptr: Pointer to "struct tomoyo_acl_info".
   *
   * Returns true if granted, false otherwise.
   */

  static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,

  				   const struct tomoyo_acl_info *ptr)
  {
  	const struct tomoyo_mount_acl *acl =
  		container_of(ptr, typeof(*acl), head);

  	return tomoyo_compare_number_union(r->param.mount.flags,
  					   &acl->flags) &&
  		tomoyo_compare_name_union(r->param.mount.type,
  					  &acl->fs_type) &&
  		tomoyo_compare_name_union(r->param.mount.dir,
  					  &acl->dir_name) &&

  		(!r->param.mount.need_dev ||

  		 tomoyo_compare_name_union(r->param.mount.dev,
  					   &acl->dev_name));

  }
  
  /**

   * tomoyo_mount_acl - Check permission for mount() operation.

   *
   * @r:        Pointer to "struct tomoyo_request_info".

   * @dev_name: Name of device file. Maybe NULL.

   * @dir:      Pointer to "struct path".
   * @type:     Name of filesystem type.
   * @flags:    Mount options.
   *
   * Returns 0 on success, negative value otherwise.
   *
   * Caller holds tomoyo_read_lock().
   */

  static int tomoyo_mount_acl(struct tomoyo_request_info *r,
  			    const char *dev_name,

  			    const struct path *dir, const char *type,

  			    unsigned long flags)

  {

  	struct tomoyo_obj_info obj = { };

  	struct path path;

  	struct file_system_type *fstype = NULL;
  	const char *requested_type = NULL;
  	const char *requested_dir_name = NULL;
  	const char *requested_dev_name = NULL;
  	struct tomoyo_path_info rtype;
  	struct tomoyo_path_info rdev;
  	struct tomoyo_path_info rdir;
  	int need_dev = 0;
  	int error = -ENOMEM;

  	r->obj = &obj;

  
  	/* Get fstype. */

  	requested_type = tomoyo_encode(type);

  	if (!requested_type)
  		goto out;
  	rtype.name = requested_type;
  	tomoyo_fill_path_info(&rtype);
  
  	/* Get mount point. */

  	obj.path2 = *dir;

  	requested_dir_name = tomoyo_realpath_from_path(dir);
  	if (!requested_dir_name) {
  		error = -ENOMEM;
  		goto out;
  	}
  	rdir.name = requested_dir_name;
  	tomoyo_fill_path_info(&rdir);
  
  	/* Compare fs name. */

  	if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {

  		/* dev_name is ignored. */

  	} else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
  		   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
  		   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
  		   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {

  		/* dev_name is ignored. */

  	} else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
  		   type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {

  		need_dev = -1; /* dev_name is a directory */
  	} else {
  		fstype = get_fs_type(type);
  		if (!fstype) {
  			error = -ENODEV;
  			goto out;
  		}
  		if (fstype->fs_flags & FS_REQUIRES_DEV)
  			/* dev_name is a block device file. */
  			need_dev = 1;
  	}
  	if (need_dev) {
  		/* Get mount point or device file. */

  		if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {

  			error = -ENOENT;
  			goto out;
  		}

  		obj.path1 = path;

  		requested_dev_name = tomoyo_realpath_from_path(&path);
  		if (!requested_dev_name) {
  			error = -ENOENT;
  			goto out;
  		}
  	} else {
  		/* Map dev_name to "<NULL>" if no dev_name given. */
  		if (!dev_name)
  			dev_name = "<NULL>";

  		requested_dev_name = tomoyo_encode(dev_name);

  		if (!requested_dev_name) {
  			error = -ENOMEM;
  			goto out;
  		}
  	}
  	rdev.name = requested_dev_name;
  	tomoyo_fill_path_info(&rdev);

  	r->param_type = TOMOYO_TYPE_MOUNT_ACL;
  	r->param.mount.need_dev = need_dev;
  	r->param.mount.dev = &rdev;
  	r->param.mount.dir = &rdir;
  	r->param.mount.type = &rtype;
  	r->param.mount.flags = flags;

  	do {
  		tomoyo_check_acl(r, tomoyo_check_mount_acl);
  		error = tomoyo_audit_mount_log(r);
  	} while (error == TOMOYO_RETRY_REQUEST);

   out:
  	kfree(requested_dev_name);
  	kfree(requested_dir_name);
  	if (fstype)
  		put_filesystem(fstype);
  	kfree(requested_type);

  	/* Drop refcount obtained by kern_path(). */
  	if (obj.path1.dentry)
  		path_put(&obj.path1);

  	return error;
  }
  
  /**

   * tomoyo_mount_permission - Check permission for mount() operation.
   *

   * @dev_name:  Name of device file. Maybe NULL.

   * @path:      Pointer to "struct path".

   * @type:      Name of filesystem type. Maybe NULL.

   * @flags:     Mount options.

   * @data_page: Optional data. Maybe NULL.

   *
   * Returns 0 on success, negative value otherwise.
   */

  int tomoyo_mount_permission(const char *dev_name, const struct path *path,

  			    const char *type, unsigned long flags,
  			    void *data_page)

  {
  	struct tomoyo_request_info r;
  	int error;
  	int idx;

  	if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
  	    == TOMOYO_CONFIG_DISABLED)

  		return 0;

  	if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
  		flags &= ~MS_MGC_MSK;
  	if (flags & MS_REMOUNT) {

  		type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];

  		flags &= ~MS_REMOUNT;

  	} else if (flags & MS_BIND) {

  		type = tomoyo_mounts[TOMOYO_MOUNT_BIND];

  		flags &= ~MS_BIND;

  	} else if (flags & MS_SHARED) {
  		if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
  			return -EINVAL;
  		type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
  		flags &= ~MS_SHARED;
  	} else if (flags & MS_PRIVATE) {
  		if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
  			return -EINVAL;

  		type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];

  		flags &= ~MS_PRIVATE;

  	} else if (flags & MS_SLAVE) {
  		if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
  			return -EINVAL;

  		type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];

  		flags &= ~MS_SLAVE;

  	} else if (flags & MS_UNBINDABLE) {
  		if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
  			return -EINVAL;
  		type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
  		flags &= ~MS_UNBINDABLE;
  	} else if (flags & MS_MOVE) {
  		type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
  		flags &= ~MS_MOVE;

  	}

  	if (!type)
  		type = "<NULL>";
  	idx = tomoyo_read_lock();
  	error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
  	tomoyo_read_unlock(idx);
  	return error;
  }