// SPDX-License-Identifier: GPL-2.0-or-later

  /* audit_fsnotify.c -- tracking inodes
   *
   * Copyright 2003-2009,2014-2015 Red Hat, Inc.
   * Copyright 2005 Hewlett-Packard Development Company, L.P.
   * Copyright 2005 IBM Corporation

   */
  
  #include <linux/kernel.h>
  #include <linux/audit.h>
  #include <linux/kthread.h>
  #include <linux/mutex.h>
  #include <linux/fs.h>
  #include <linux/fsnotify_backend.h>
  #include <linux/namei.h>
  #include <linux/netlink.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/security.h>
  #include "audit.h"
  
  /*
   * this mark lives on the parent directory of the inode in question.
   * but dev, ino, and path are about the child
   */
  struct audit_fsnotify_mark {
  	dev_t dev;		/* associated superblock device */
  	unsigned long ino;	/* associated inode number */
  	char *path;		/* insertion path */
  	struct fsnotify_mark mark; /* fsnotify mark on the inode */
  	struct audit_krule *rule;
  };
  
  /* fsnotify handle. */
  static struct fsnotify_group *audit_fsnotify_group;
  
  /* fsnotify events we care about. */
  #define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\

  			 FS_MOVE_SELF)

  
  static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
  {
  	kfree(audit_mark->path);
  	kfree(audit_mark);
  }
  
  static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
  {
  	struct audit_fsnotify_mark *audit_mark;
  
  	audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
  	audit_fsnotify_mark_free(audit_mark);
  }
  
  char *audit_mark_path(struct audit_fsnotify_mark *mark)
  {
  	return mark->path;
  }
  
  int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
  {
  	if (mark->ino == AUDIT_INO_UNSET)
  		return 0;
  	return (mark->ino == ino) && (mark->dev == dev);
  }
  
  static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,

  			     const struct inode *inode)

  {
  	audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
  	audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
  }
  
  struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
  {
  	struct audit_fsnotify_mark *audit_mark;
  	struct path path;
  	struct dentry *dentry;
  	struct inode *inode;
  	int ret;
  
  	if (pathname[0] != '/' || pathname[len-1] == '/')
  		return ERR_PTR(-EINVAL);
  
  	dentry = kern_path_locked(pathname, &path);
  	if (IS_ERR(dentry))
  		return (void *)dentry; /* returning an error */
  	inode = path.dentry->d_inode;

  	inode_unlock(inode);

  
  	audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
  	if (unlikely(!audit_mark)) {
  		audit_mark = ERR_PTR(-ENOMEM);
  		goto out;
  	}

  	fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);

  	audit_mark->mark.mask = AUDIT_FS_EVENTS;
  	audit_mark->path = pathname;
  	audit_update_mark(audit_mark, dentry->d_inode);
  	audit_mark->rule = krule;

  	ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);

  	if (ret < 0) {

  		fsnotify_put_mark(&audit_mark->mark);

  		audit_mark = ERR_PTR(ret);
  	}
  out:
  	dput(dentry);
  	path_put(&path);
  	return audit_mark;
  }
  
  static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
  {
  	struct audit_buffer *ab;
  	struct audit_krule *rule = audit_mark->rule;
  
  	if (!audit_enabled)
  		return;

  	ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);

  	if (unlikely(!ab))
  		return;

  	audit_log_session_info(ab);

  	audit_log_format(ab, " op=%s path=", op);

  	audit_log_untrustedstring(ab, audit_mark->path);
  	audit_log_key(ab, rule->filterkey);
  	audit_log_format(ab, " list=%d res=1", rule->listnr);
  	audit_log_end(ab);
  }
  
  void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
  {
  	fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
  	fsnotify_put_mark(&audit_mark->mark);
  }
  
  void audit_remove_mark_rule(struct audit_krule *krule)
  {
  	struct audit_fsnotify_mark *mark = krule->exe;
  
  	audit_remove_mark(mark);
  }
  
  static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
  {
  	struct audit_krule *rule = audit_mark->rule;
  	struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
  
  	audit_mark_log_rule_change(audit_mark, "autoremove_rule");
  	audit_del_rule(entry);
  }
  
  /* Update mark data in audit rules based on fsnotify events. */

  static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
  				   struct inode *inode, struct inode *dir,

  				   const struct qstr *dname, u32 cookie)

  {
  	struct audit_fsnotify_mark *audit_mark;

  
  	audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);

  	if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group) ||
  	    WARN_ON_ONCE(!inode))

  		return 0;

  
  	if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {

  		if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))

  			return 0;
  		audit_update_mark(audit_mark, inode);

  	} else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) {

  		audit_autoremove_mark_rule(audit_mark);

  	}

  
  	return 0;
  }
  
  static const struct fsnotify_ops audit_mark_fsnotify_ops = {

  	.handle_inode_event = audit_mark_handle_event,

  	.free_mark = audit_fsnotify_free_mark,

  };
  
  static int __init audit_fsnotify_init(void)
  {
  	audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
  	if (IS_ERR(audit_fsnotify_group)) {
  		audit_fsnotify_group = NULL;
  		audit_panic("cannot create audit fsnotify group");
  	}
  	return 0;
  }
  device_initcall(audit_fsnotify_init);