/*
   * NetLabel Kernel API
   *
   * This file defines the kernel API for the NetLabel system.  The NetLabel
   * system manages static and dynamic label mappings for network protocols such
   * as CIPSO and RIPSO.
   *
   * Author: Paul Moore <paul.moore@hp.com>
   *
   */
  
  /*
   * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
   *
   * 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; either version 2 of the License, or
   * (at your option) any later version.
   *
   * 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/init.h>
  #include <linux/types.h>
  #include <net/ip.h>
  #include <net/netlabel.h>
  #include <net/cipso_ipv4.h>
  #include <asm/bug.h>
  
  #include "netlabel_domainhash.h"
  #include "netlabel_unlabeled.h"
  #include "netlabel_user.h"

  #include "netlabel_mgmt.h"

  
  /*

   * Security Attribute Functions
   */
  
  /**
   * netlbl_secattr_catmap_walk - Walk a LSM secattr catmap looking for a bit
   * @catmap: the category bitmap
   * @offset: the offset to start searching at, in bits
   *
   * Description:
   * This function walks a LSM secattr category bitmap starting at @offset and
   * returns the spot of the first set bit or -ENOENT if no bits are set.
   *
   */
  int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
  			       u32 offset)
  {
  	struct netlbl_lsm_secattr_catmap *iter = catmap;
  	u32 node_idx;
  	u32 node_bit;
  	NETLBL_CATMAP_MAPTYPE bitmap;
  
  	if (offset > iter->startbit) {
  		while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
  			iter = iter->next;
  			if (iter == NULL)
  				return -ENOENT;
  		}
  		node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
  		node_bit = offset - iter->startbit -
  			   (NETLBL_CATMAP_MAPSIZE * node_idx);
  	} else {
  		node_idx = 0;
  		node_bit = 0;
  	}
  	bitmap = iter->bitmap[node_idx] >> node_bit;
  
  	for (;;) {
  		if (bitmap != 0) {
  			while ((bitmap & NETLBL_CATMAP_BIT) == 0) {
  				bitmap >>= 1;
  				node_bit++;
  			}
  			return iter->startbit +
  				(NETLBL_CATMAP_MAPSIZE * node_idx) + node_bit;
  		}
  		if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
  			if (iter->next != NULL) {
  				iter = iter->next;
  				node_idx = 0;
  			} else
  				return -ENOENT;
  		}
  		bitmap = iter->bitmap[node_idx];
  		node_bit = 0;
  	}
  
  	return -ENOENT;
  }
  
  /**
   * netlbl_secattr_catmap_walk_rng - Find the end of a string of set bits
   * @catmap: the category bitmap
   * @offset: the offset to start searching at, in bits
   *
   * Description:
   * This function walks a LSM secattr category bitmap starting at @offset and
   * returns the spot of the first cleared bit or -ENOENT if the offset is past
   * the end of the bitmap.
   *
   */
  int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
  				   u32 offset)
  {
  	struct netlbl_lsm_secattr_catmap *iter = catmap;
  	u32 node_idx;
  	u32 node_bit;
  	NETLBL_CATMAP_MAPTYPE bitmask;
  	NETLBL_CATMAP_MAPTYPE bitmap;
  
  	if (offset > iter->startbit) {
  		while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
  			iter = iter->next;
  			if (iter == NULL)
  				return -ENOENT;
  		}
  		node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
  		node_bit = offset - iter->startbit -
  			   (NETLBL_CATMAP_MAPSIZE * node_idx);
  	} else {
  		node_idx = 0;
  		node_bit = 0;
  	}
  	bitmask = NETLBL_CATMAP_BIT << node_bit;
  
  	for (;;) {
  		bitmap = iter->bitmap[node_idx];
  		while (bitmask != 0 && (bitmap & bitmask) != 0) {
  			bitmask <<= 1;
  			node_bit++;
  		}
  
  		if (bitmask != 0)
  			return iter->startbit +
  				(NETLBL_CATMAP_MAPSIZE * node_idx) +
  				node_bit - 1;
  		else if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
  			if (iter->next == NULL)
  				return iter->startbit +	NETLBL_CATMAP_SIZE - 1;
  			iter = iter->next;
  			node_idx = 0;
  		}
  		bitmask = NETLBL_CATMAP_BIT;
  		node_bit = 0;
  	}
  
  	return -ENOENT;
  }
  
  /**
   * netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
   * @catmap: the category bitmap
   * @bit: the bit to set
   * @flags: memory allocation flags
   *
   * Description:
   * Set the bit specified by @bit in @catmap.  Returns zero on success,
   * negative values on failure.
   *
   */
  int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
  				 u32 bit,
  				 gfp_t flags)
  {
  	struct netlbl_lsm_secattr_catmap *iter = catmap;
  	u32 node_bit;
  	u32 node_idx;
  
  	while (iter->next != NULL &&
  	       bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
  		iter = iter->next;
  	if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
  		iter->next = netlbl_secattr_catmap_alloc(flags);
  		if (iter->next == NULL)
  			return -ENOMEM;
  		iter = iter->next;
  		iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
  	}
  
  	/* gcc always rounds to zero when doing integer division */
  	node_idx = (bit - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
  	node_bit = bit - iter->startbit - (NETLBL_CATMAP_MAPSIZE * node_idx);
  	iter->bitmap[node_idx] |= NETLBL_CATMAP_BIT << node_bit;
  
  	return 0;
  }
  
  /**
   * netlbl_secattr_catmap_setrng - Set a range of bits in a LSM secattr catmap
   * @catmap: the category bitmap
   * @start: the starting bit
   * @end: the last bit in the string
   * @flags: memory allocation flags
   *
   * Description:
   * Set a range of bits, starting at @start and ending with @end.  Returns zero
   * on success, negative values on failure.
   *
   */
  int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
  				 u32 start,
  				 u32 end,
  				 gfp_t flags)
  {
  	int ret_val = 0;
  	struct netlbl_lsm_secattr_catmap *iter = catmap;
  	u32 iter_max_spot;
  	u32 spot;
  
  	/* XXX - This could probably be made a bit faster by combining writes
  	 * to the catmap instead of setting a single bit each time, but for
  	 * right now skipping to the start of the range in the catmap should
  	 * be a nice improvement over calling the individual setbit function
  	 * repeatedly from a loop. */
  
  	while (iter->next != NULL &&
  	       start >= (iter->startbit + NETLBL_CATMAP_SIZE))
  		iter = iter->next;
  	iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
  
  	for (spot = start; spot <= end && ret_val == 0; spot++) {
  		if (spot >= iter_max_spot && iter->next != NULL) {
  			iter = iter->next;
  			iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
  		}
  		ret_val = netlbl_secattr_catmap_setbit(iter, spot, GFP_ATOMIC);
  	}
  
  	return ret_val;
  }
  
  /*

   * LSM Functions
   */
  
  /**

   * netlbl_enabled - Determine if the NetLabel subsystem is enabled
   *
   * Description:
   * The LSM can use this function to determine if it should use NetLabel
   * security attributes in it's enforcement mechanism.  Currently, NetLabel is
   * considered to be enabled when it's configuration contains a valid setup for
   * at least one labeled protocol (i.e. NetLabel can understand incoming
   * labeled packets of at least one type); otherwise NetLabel is considered to
   * be disabled.
   *
   */
  int netlbl_enabled(void)
  {
  	/* At some point we probably want to expose this mechanism to the user
  	 * as well so that admins can toggle NetLabel regardless of the
  	 * configuration */
  	return (netlbl_mgmt_protocount_value() > 0 ? 1 : 0);
  }
  
  /**

   * netlbl_socket_setattr - Label a socket using the correct protocol

   * @sk: the socket to label

   * @secattr: the security attributes
   *
   * Description:
   * Attach the correct label to the given socket using the security attributes

   * specified in @secattr.  This function requires exclusive access to @sk,
   * which means it either needs to be in the process of being created or locked.
   * Returns zero on success, negative values on failure.

   *
   */

  int netlbl_sock_setattr(struct sock *sk,
  			const struct netlbl_lsm_secattr *secattr)

  {
  	int ret_val = -ENOENT;
  	struct netlbl_dom_map *dom_entry;
  
  	rcu_read_lock();
  	dom_entry = netlbl_domhsh_getentry(secattr->domain);
  	if (dom_entry == NULL)
  		goto socket_setattr_return;
  	switch (dom_entry->type) {
  	case NETLBL_NLTYPE_CIPSOV4:

  		ret_val = cipso_v4_sock_setattr(sk,
  						dom_entry->type_def.cipsov4,
  						secattr);

  		break;
  	case NETLBL_NLTYPE_UNLABELED:
  		ret_val = 0;
  		break;
  	default:
  		ret_val = -ENOENT;
  	}
  
  socket_setattr_return:
  	rcu_read_unlock();
  	return ret_val;
  }
  
  /**

   * netlbl_sock_getattr - Determine the security attributes of a sock
   * @sk: the sock
   * @secattr: the security attributes
   *
   * Description:
   * Examines the given sock to see any NetLabel style labeling has been
   * applied to the sock, if so it parses the socket label and returns the
   * security attributes in @secattr.  Returns zero on success, negative values
   * on failure.
   *
   */
  int netlbl_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  
  	ret_val = cipso_v4_sock_getattr(sk, secattr);
  	if (ret_val == 0)
  		return 0;
  
  	return netlbl_unlabel_getattr(secattr);
  }
  
  /**

   * netlbl_skbuff_getattr - Determine the security attributes of a packet
   * @skb: the packet
   * @secattr: the security attributes
   *
   * Description:
   * Examines the given packet to see if a recognized form of packet labeling
   * is present, if so it parses the packet label and returns the security
   * attributes in @secattr.  Returns zero on success, negative values on
   * failure.
   *
   */
  int netlbl_skbuff_getattr(const struct sk_buff *skb,
  			  struct netlbl_lsm_secattr *secattr)
  {

  	if (CIPSO_V4_OPTEXIST(skb) &&
  	    cipso_v4_skbuff_getattr(skb, secattr) == 0)

  		return 0;
  
  	return netlbl_unlabel_getattr(secattr);
  }
  
  /**
   * netlbl_skbuff_err - Handle a LSM error on a sk_buff
   * @skb: the packet
   * @error: the error code
   *
   * Description:
   * Deal with a LSM problem when handling the packet in @skb, typically this is
   * a permission denied problem (-EACCES).  The correct action is determined
   * according to the packet's labeling protocol.
   *
   */
  void netlbl_skbuff_err(struct sk_buff *skb, int error)
  {
  	if (CIPSO_V4_OPTEXIST(skb))
  		cipso_v4_error(skb, error, 0);
  }
  
  /**
   * netlbl_cache_invalidate - Invalidate all of the NetLabel protocol caches
   *
   * Description:
   * For all of the NetLabel protocols that support some form of label mapping
   * cache, invalidate the cache.  Returns zero on success, negative values on
   * error.
   *
   */
  void netlbl_cache_invalidate(void)
  {
  	cipso_v4_cache_invalidate();
  }
  
  /**
   * netlbl_cache_add - Add an entry to a NetLabel protocol cache
   * @skb: the packet
   * @secattr: the packet's security attributes
   *
   * Description:
   * Add the LSM security attributes for the given packet to the underlying
   * NetLabel protocol's label mapping cache.  Returns zero on success, negative
   * values on error.
   *
   */
  int netlbl_cache_add(const struct sk_buff *skb,
  		     const struct netlbl_lsm_secattr *secattr)
  {

  	if ((secattr->flags & NETLBL_SECATTR_CACHE) == 0)

  		return -ENOMSG;
  
  	if (CIPSO_V4_OPTEXIST(skb))
  		return cipso_v4_cache_add(skb, secattr);
  
  	return -ENOMSG;
  }
  
  /*
   * Setup Functions
   */
  
  /**
   * netlbl_init - Initialize NetLabel
   *
   * Description:
   * Perform the required NetLabel initialization before first use.
   *
   */
  static int __init netlbl_init(void)
  {
  	int ret_val;
  
  	printk(KERN_INFO "NetLabel: Initializing
  ");
  	printk(KERN_INFO "NetLabel:  domain hash size = %u
  ",
  	       (1 << NETLBL_DOMHSH_BITSIZE));
  	printk(KERN_INFO "NetLabel:  protocols ="
  	       " UNLABELED"
  	       " CIPSOv4"
  	       "
  ");
  
  	ret_val = netlbl_domhsh_init(NETLBL_DOMHSH_BITSIZE);
  	if (ret_val != 0)
  		goto init_failure;
  
  	ret_val = netlbl_netlink_init();
  	if (ret_val != 0)
  		goto init_failure;
  
  	ret_val = netlbl_unlabel_defconf();
  	if (ret_val != 0)
  		goto init_failure;
  	printk(KERN_INFO "NetLabel:  unlabeled traffic allowed by default
  ");
  
  	return 0;
  
  init_failure:
  	panic("NetLabel: failed to initialize properly (%d)
  ", ret_val);
  }
  
  subsys_initcall(netlbl_init);