/*
   * Copyright (C) 2008 IBM Corporation
   *
   * Authors:
   * Mimi Zohar <zohar@us.ibm.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation, version 2 of the
   * License.
   *
   * File: integrity_iint.c
   *	- implements the integrity hooks: integrity_inode_alloc,
   *	  integrity_inode_free
   *	- cache integrity information associated with an inode
   *	  using a rbtree tree.
   */
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/spinlock.h>
  #include <linux/rbtree.h>

  #include <linux/file.h>
  #include <linux/uaccess.h>

  #include "integrity.h"
  
  static struct rb_root integrity_iint_tree = RB_ROOT;

  static DEFINE_RWLOCK(integrity_iint_lock);

  static struct kmem_cache *iint_cache __read_mostly;

  /*
   * __integrity_iint_find - return the iint associated with an inode
   */
  static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
  {
  	struct integrity_iint_cache *iint;
  	struct rb_node *n = integrity_iint_tree.rb_node;

  	while (n) {
  		iint = rb_entry(n, struct integrity_iint_cache, rb_node);
  
  		if (inode < iint->inode)
  			n = n->rb_left;
  		else if (inode > iint->inode)
  			n = n->rb_right;
  		else
  			break;
  	}
  	if (!n)
  		return NULL;
  
  	return iint;
  }
  
  /*
   * integrity_iint_find - return the iint associated with an inode
   */
  struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  {
  	struct integrity_iint_cache *iint;
  
  	if (!IS_IMA(inode))
  		return NULL;

  	read_lock(&integrity_iint_lock);

  	iint = __integrity_iint_find(inode);

  	read_unlock(&integrity_iint_lock);

  
  	return iint;
  }
  
  static void iint_free(struct integrity_iint_cache *iint)
  {

  	kfree(iint->ima_hash);
  	iint->ima_hash = NULL;

  	iint->version = 0;
  	iint->flags = 0UL;

  	iint->ima_file_status = INTEGRITY_UNKNOWN;
  	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  	iint->ima_module_status = INTEGRITY_UNKNOWN;

  	iint->evm_status = INTEGRITY_UNKNOWN;

  	kmem_cache_free(iint_cache, iint);
  }
  
  /**

   * integrity_inode_get - find or allocate an iint associated with an inode

   * @inode: pointer to the inode

   * @return: allocated iint
   *
   * Caller must lock i_mutex

   */

  struct integrity_iint_cache *integrity_inode_get(struct inode *inode)

  {
  	struct rb_node **p;

  	struct rb_node *node, *parent = NULL;
  	struct integrity_iint_cache *iint, *test_iint;

  	iint = integrity_iint_find(inode);
  	if (iint)
  		return iint;

  	iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  	if (!iint)
  		return NULL;

  	write_lock(&integrity_iint_lock);

  
  	p = &integrity_iint_tree.rb_node;
  	while (*p) {
  		parent = *p;
  		test_iint = rb_entry(parent, struct integrity_iint_cache,
  				     rb_node);

  		if (inode < test_iint->inode)
  			p = &(*p)->rb_left;

  		else

  			p = &(*p)->rb_right;

  	}

  	iint->inode = inode;
  	node = &iint->rb_node;

  	inode->i_flags |= S_IMA;

  	rb_link_node(node, parent, p);
  	rb_insert_color(node, &integrity_iint_tree);

  	write_unlock(&integrity_iint_lock);

  	return iint;

  }
  
  /**
   * integrity_inode_free - called on security_inode_free
   * @inode: pointer to the inode
   *
   * Free the integrity information(iint) associated with an inode.
   */
  void integrity_inode_free(struct inode *inode)
  {
  	struct integrity_iint_cache *iint;
  
  	if (!IS_IMA(inode))
  		return;

  	write_lock(&integrity_iint_lock);

  	iint = __integrity_iint_find(inode);
  	rb_erase(&iint->rb_node, &integrity_iint_tree);

  	write_unlock(&integrity_iint_lock);

  
  	iint_free(iint);
  }
  
  static void init_once(void *foo)
  {
  	struct integrity_iint_cache *iint = foo;

  	memset(iint, 0, sizeof(*iint));

  	iint->version = 0;
  	iint->flags = 0UL;

  	iint->ima_file_status = INTEGRITY_UNKNOWN;
  	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  	iint->ima_module_status = INTEGRITY_UNKNOWN;

  	iint->evm_status = INTEGRITY_UNKNOWN;

  }
  
  static int __init integrity_iintcache_init(void)
  {
  	iint_cache =
  	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
  			      0, SLAB_PANIC, init_once);

  	return 0;
  }
  security_initcall(integrity_iintcache_init);

  
  
  /*
   * integrity_kernel_read - read data from the file
   *
   * This is a function for reading file content instead of kernel_read().
   * It does not perform locking checks to ensure it cannot be blocked.
   * It does not perform security checks because it is irrelevant for IMA.
   *
   */
  int integrity_kernel_read(struct file *file, loff_t offset,
  			  char *addr, unsigned long count)
  {
  	mm_segment_t old_fs;
  	char __user *buf = (char __user *)addr;

  	ssize_t ret;

  
  	if (!(file->f_mode & FMODE_READ))
  		return -EBADF;
  
  	old_fs = get_fs();
  	set_fs(get_ds());

  	ret = __vfs_read(file, buf, count, &offset);

  	set_fs(old_fs);

  	return ret;
  }
  
  /*
   * integrity_read_file - read entire file content into the buffer
   *
   * This is function opens a file, allocates the buffer of required
   * size, read entire file content to the buffer and closes the file
   *
   * It is used only by init code.
   *
   */
  int __init integrity_read_file(const char *path, char **data)
  {
  	struct file *file;
  	loff_t size;
  	char *buf;
  	int rc = -EINVAL;
  
  	file = filp_open(path, O_RDONLY, 0);
  	if (IS_ERR(file)) {
  		rc = PTR_ERR(file);
  		pr_err("Unable to open file: %s (%d)", path, rc);
  		return rc;
  	}
  
  	size = i_size_read(file_inode(file));
  	if (size <= 0)
  		goto out;
  
  	buf = kmalloc(size, GFP_KERNEL);
  	if (!buf) {
  		rc = -ENOMEM;
  		goto out;
  	}
  
  	rc = integrity_kernel_read(file, 0, buf, size);
  	if (rc < 0)
  		kfree(buf);
  	else if (rc != size)
  		rc = -EIO;
  	else
  		*data = buf;
  out:
  	fput(file);
  	return rc;
  }

  
  /*
   * integrity_load_keys - load integrity keys hook
   *
   * Hooks is called from init/main.c:kernel_init_freeable()
   * when rootfs is ready
   */
  void __init integrity_load_keys(void)
  {
  	ima_load_x509();
  }