/*
   * CIPSO - Commercial IP Security Option
   *
   * This is an implementation of the CIPSO 2.2 protocol as specified in
   * draft-ietf-cipso-ipsecurity-01.txt with additional tag types as found in

   * FIPS-188.  While CIPSO never became a full IETF RFC standard many vendors

   * have chosen to adopt the protocol and over the years it has become a
   * de-facto standard for labeled networking.
   *

   * The CIPSO draft specification can be found in the kernel's Documentation
   * directory as well as the following URL:

   *   http://tools.ietf.org/id/draft-ietf-cipso-ipsecurity-01.txt

   * The FIPS-188 specification can be found at the following URL:
   *   http://www.itl.nist.gov/fipspubs/fip188.htm
   *

   * Author: Paul Moore <paul.moore@hp.com>
   *
   */
  
  /*

   * (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008

   *
   * 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 <linux/rcupdate.h>
  #include <linux/list.h>
  #include <linux/spinlock.h>
  #include <linux/string.h>
  #include <linux/jhash.h>

  #include <linux/audit.h>

  #include <linux/slab.h>

  #include <net/ip.h>
  #include <net/icmp.h>
  #include <net/tcp.h>
  #include <net/netlabel.h>
  #include <net/cipso_ipv4.h>

  #include <linux/atomic.h>

  #include <asm/bug.h>

  #include <asm/unaligned.h>

  /* List of available DOI definitions */

  /* XXX - This currently assumes a minimal number of different DOIs in use,
   * if in practice there are a lot of different DOIs this list should
   * probably be turned into a hash table or something similar so we
   * can do quick lookups. */

  static DEFINE_SPINLOCK(cipso_v4_doi_list_lock);

  static LIST_HEAD(cipso_v4_doi_list);

  
  /* Label mapping cache */
  int cipso_v4_cache_enabled = 1;
  int cipso_v4_cache_bucketsize = 10;
  #define CIPSO_V4_CACHE_BUCKETBITS     7
  #define CIPSO_V4_CACHE_BUCKETS        (1 << CIPSO_V4_CACHE_BUCKETBITS)
  #define CIPSO_V4_CACHE_REORDERLIMIT   10
  struct cipso_v4_map_cache_bkt {
  	spinlock_t lock;
  	u32 size;
  	struct list_head list;
  };
  struct cipso_v4_map_cache_entry {
  	u32 hash;
  	unsigned char *key;
  	size_t key_len;

  	struct netlbl_lsm_cache *lsm_data;

  
  	u32 activity;
  	struct list_head list;
  };
  static struct cipso_v4_map_cache_bkt *cipso_v4_cache = NULL;
  
  /* Restricted bitmap (tag #1) flags */
  int cipso_v4_rbm_optfmt = 0;
  int cipso_v4_rbm_strictvalid = 1;
  
  /*

   * Protocol Constants
   */
  
  /* Maximum size of the CIPSO IP option, derived from the fact that the maximum
   * IPv4 header size is 60 bytes and the base IPv4 header is 20 bytes long. */
  #define CIPSO_V4_OPT_LEN_MAX          40
  
  /* Length of the base CIPSO option, this includes the option type (1 byte), the
   * option length (1 byte), and the DOI (4 bytes). */
  #define CIPSO_V4_HDR_LEN              6
  
  /* Base length of the restrictive category bitmap tag (tag #1). */
  #define CIPSO_V4_TAG_RBM_BLEN         4
  
  /* Base length of the enumerated category tag (tag #2). */
  #define CIPSO_V4_TAG_ENUM_BLEN        4
  
  /* Base length of the ranged categories bitmap tag (tag #5). */
  #define CIPSO_V4_TAG_RNG_BLEN         4
  /* The maximum number of category ranges permitted in the ranged category tag
   * (tag #5).  You may note that the IETF draft states that the maximum number
   * of category ranges is 7, but if the low end of the last category range is

   * zero then it is possible to fit 8 category ranges because the zero should

   * be omitted. */
  #define CIPSO_V4_TAG_RNG_CAT_MAX      8

  /* Base length of the local tag (non-standard tag).
   *  Tag definition (may change between kernel versions)
   *
   * 0          8          16         24         32
   * +----------+----------+----------+----------+
   * | 10000000 | 00000110 | 32-bit secid value  |
   * +----------+----------+----------+----------+
   * | in (host byte order)|
   * +----------+----------+
   *
   */
  #define CIPSO_V4_TAG_LOC_BLEN         6

  /*

   * Helper Functions
   */
  
  /**
   * cipso_v4_bitmap_walk - Walk a bitmap looking for a bit
   * @bitmap: the bitmap
   * @bitmap_len: length in bits
   * @offset: starting offset
   * @state: if non-zero, look for a set (1) bit else look for a cleared (0) bit
   *
   * Description:
   * Starting at @offset, walk the bitmap from left to right until either the
   * desired bit is found or we reach the end.  Return the bit offset, -1 if
   * not found, or -2 if error.
   */
  static int cipso_v4_bitmap_walk(const unsigned char *bitmap,
  				u32 bitmap_len,
  				u32 offset,
  				u8 state)
  {
  	u32 bit_spot;
  	u32 byte_offset;
  	unsigned char bitmask;
  	unsigned char byte;
  
  	/* gcc always rounds to zero when doing integer division */
  	byte_offset = offset / 8;
  	byte = bitmap[byte_offset];
  	bit_spot = offset;
  	bitmask = 0x80 >> (offset % 8);
  
  	while (bit_spot < bitmap_len) {
  		if ((state && (byte & bitmask) == bitmask) ||
  		    (state == 0 && (byte & bitmask) == 0))
  			return bit_spot;
  
  		bit_spot++;
  		bitmask >>= 1;
  		if (bitmask == 0) {
  			byte = bitmap[++byte_offset];
  			bitmask = 0x80;
  		}
  	}
  
  	return -1;
  }
  
  /**
   * cipso_v4_bitmap_setbit - Sets a single bit in a bitmap
   * @bitmap: the bitmap
   * @bit: the bit
   * @state: if non-zero, set the bit (1) else clear the bit (0)
   *
   * Description:
   * Set a single bit in the bitmask.  Returns zero on success, negative values
   * on error.
   */
  static void cipso_v4_bitmap_setbit(unsigned char *bitmap,
  				   u32 bit,
  				   u8 state)
  {
  	u32 byte_spot;
  	u8 bitmask;
  
  	/* gcc always rounds to zero when doing integer division */
  	byte_spot = bit / 8;
  	bitmask = 0x80 >> (bit % 8);
  	if (state)
  		bitmap[byte_spot] |= bitmask;
  	else
  		bitmap[byte_spot] &= ~bitmask;
  }
  
  /**

   * cipso_v4_cache_entry_free - Frees a cache entry
   * @entry: the entry to free
   *
   * Description:

   * This function frees the memory associated with a cache entry including the
   * LSM cache data if there are no longer any users, i.e. reference count == 0.

   *
   */
  static void cipso_v4_cache_entry_free(struct cipso_v4_map_cache_entry *entry)
  {

  	if (entry->lsm_data)
  		netlbl_secattr_cache_free(entry->lsm_data);

  	kfree(entry->key);
  	kfree(entry);
  }
  
  /**
   * cipso_v4_map_cache_hash - Hashing function for the CIPSO cache
   * @key: the hash key
   * @key_len: the length of the key in bytes
   *
   * Description:
   * The CIPSO tag hashing function.  Returns a 32-bit hash value.
   *
   */
  static u32 cipso_v4_map_cache_hash(const unsigned char *key, u32 key_len)
  {
  	return jhash(key, key_len, 0);
  }
  
  /*
   * Label Mapping Cache Functions
   */
  
  /**
   * cipso_v4_cache_init - Initialize the CIPSO cache
   *
   * Description:
   * Initializes the CIPSO label mapping cache, this function should be called
   * before any of the other functions defined in this file.  Returns zero on
   * success, negative values on error.
   *
   */
  static int cipso_v4_cache_init(void)
  {
  	u32 iter;
  
  	cipso_v4_cache = kcalloc(CIPSO_V4_CACHE_BUCKETS,
  				 sizeof(struct cipso_v4_map_cache_bkt),
  				 GFP_KERNEL);
  	if (cipso_v4_cache == NULL)
  		return -ENOMEM;
  
  	for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {
  		spin_lock_init(&cipso_v4_cache[iter].lock);
  		cipso_v4_cache[iter].size = 0;
  		INIT_LIST_HEAD(&cipso_v4_cache[iter].list);
  	}
  
  	return 0;
  }
  
  /**
   * cipso_v4_cache_invalidate - Invalidates the current CIPSO cache
   *
   * Description:
   * Invalidates and frees any entries in the CIPSO cache.  Returns zero on
   * success and negative values on failure.
   *
   */
  void cipso_v4_cache_invalidate(void)
  {
  	struct cipso_v4_map_cache_entry *entry, *tmp_entry;
  	u32 iter;
  
  	for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {

  		spin_lock_bh(&cipso_v4_cache[iter].lock);

  		list_for_each_entry_safe(entry,
  					 tmp_entry,
  					 &cipso_v4_cache[iter].list, list) {
  			list_del(&entry->list);
  			cipso_v4_cache_entry_free(entry);
  		}
  		cipso_v4_cache[iter].size = 0;

  		spin_unlock_bh(&cipso_v4_cache[iter].lock);

  	}

  }
  
  /**
   * cipso_v4_cache_check - Check the CIPSO cache for a label mapping
   * @key: the buffer to check
   * @key_len: buffer length in bytes
   * @secattr: the security attribute struct to use
   *
   * Description:
   * This function checks the cache to see if a label mapping already exists for
   * the given key.  If there is a match then the cache is adjusted and the
   * @secattr struct is populated with the correct LSM security attributes.  The
   * cache is adjusted in the following manner if the entry is not already the
   * first in the cache bucket:
   *
   *  1. The cache entry's activity counter is incremented
   *  2. The previous (higher ranking) entry's activity counter is decremented
   *  3. If the difference between the two activity counters is geater than
   *     CIPSO_V4_CACHE_REORDERLIMIT the two entries are swapped
   *
   * Returns zero on success, -ENOENT for a cache miss, and other negative values
   * on error.
   *
   */
  static int cipso_v4_cache_check(const unsigned char *key,
  				u32 key_len,
  				struct netlbl_lsm_secattr *secattr)
  {
  	u32 bkt;
  	struct cipso_v4_map_cache_entry *entry;
  	struct cipso_v4_map_cache_entry *prev_entry = NULL;
  	u32 hash;
  
  	if (!cipso_v4_cache_enabled)
  		return -ENOENT;
  
  	hash = cipso_v4_map_cache_hash(key, key_len);

  	bkt = hash & (CIPSO_V4_CACHE_BUCKETS - 1);

  	spin_lock_bh(&cipso_v4_cache[bkt].lock);

  	list_for_each_entry(entry, &cipso_v4_cache[bkt].list, list) {
  		if (entry->hash == hash &&
  		    entry->key_len == key_len &&
  		    memcmp(entry->key, key, key_len) == 0) {
  			entry->activity += 1;

  			atomic_inc(&entry->lsm_data->refcount);
  			secattr->cache = entry->lsm_data;

  			secattr->flags |= NETLBL_SECATTR_CACHE;

  			secattr->type = NETLBL_NLTYPE_CIPSOV4;

  			if (prev_entry == NULL) {

  				spin_unlock_bh(&cipso_v4_cache[bkt].lock);

  				return 0;
  			}
  
  			if (prev_entry->activity > 0)
  				prev_entry->activity -= 1;
  			if (entry->activity > prev_entry->activity &&
  			    entry->activity - prev_entry->activity >
  			    CIPSO_V4_CACHE_REORDERLIMIT) {
  				__list_del(entry->list.prev, entry->list.next);
  				__list_add(&entry->list,
  					   prev_entry->list.prev,
  					   &prev_entry->list);
  			}

  			spin_unlock_bh(&cipso_v4_cache[bkt].lock);

  			return 0;
  		}
  		prev_entry = entry;
  	}

  	spin_unlock_bh(&cipso_v4_cache[bkt].lock);

  
  	return -ENOENT;
  }
  
  /**
   * cipso_v4_cache_add - Add an entry to the CIPSO cache
   * @skb: the packet
   * @secattr: the packet's security attributes
   *
   * Description:
   * Add a new entry into the CIPSO label mapping cache.  Add the new entry to
   * head of the cache bucket's list, if the cache bucket is out of room remove
   * the last entry in the list first.  It is important to note that there is
   * currently no checking for duplicate keys.  Returns zero on success,
   * negative values on failure.
   *
   */
  int cipso_v4_cache_add(const struct sk_buff *skb,
  		       const struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val = -EPERM;
  	u32 bkt;
  	struct cipso_v4_map_cache_entry *entry = NULL;
  	struct cipso_v4_map_cache_entry *old_entry = NULL;
  	unsigned char *cipso_ptr;
  	u32 cipso_ptr_len;
  
  	if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 0)
  		return 0;
  
  	cipso_ptr = CIPSO_V4_OPTPTR(skb);
  	cipso_ptr_len = cipso_ptr[1];
  
  	entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
  	if (entry == NULL)
  		return -ENOMEM;

  	entry->key = kmemdup(cipso_ptr, cipso_ptr_len, GFP_ATOMIC);

  	if (entry->key == NULL) {
  		ret_val = -ENOMEM;
  		goto cache_add_failure;
  	}

  	entry->key_len = cipso_ptr_len;
  	entry->hash = cipso_v4_map_cache_hash(cipso_ptr, cipso_ptr_len);

  	atomic_inc(&secattr->cache->refcount);
  	entry->lsm_data = secattr->cache;

  	bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);

  	spin_lock_bh(&cipso_v4_cache[bkt].lock);

  	if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
  		list_add(&entry->list, &cipso_v4_cache[bkt].list);
  		cipso_v4_cache[bkt].size += 1;
  	} else {
  		old_entry = list_entry(cipso_v4_cache[bkt].list.prev,
  				       struct cipso_v4_map_cache_entry, list);
  		list_del(&old_entry->list);
  		list_add(&entry->list, &cipso_v4_cache[bkt].list);
  		cipso_v4_cache_entry_free(old_entry);
  	}

  	spin_unlock_bh(&cipso_v4_cache[bkt].lock);

  
  	return 0;
  
  cache_add_failure:
  	if (entry)
  		cipso_v4_cache_entry_free(entry);
  	return ret_val;
  }
  
  /*
   * DOI List Functions
   */
  
  /**
   * cipso_v4_doi_search - Searches for a DOI definition
   * @doi: the DOI to search for
   *
   * Description:
   * Search the DOI definition list for a DOI definition with a DOI value that

   * matches @doi.  The caller is responsible for calling rcu_read_[un]lock().

   * Returns a pointer to the DOI definition on success and NULL on failure.
   */
  static struct cipso_v4_doi *cipso_v4_doi_search(u32 doi)
  {
  	struct cipso_v4_doi *iter;
  
  	list_for_each_entry_rcu(iter, &cipso_v4_doi_list, list)

  		if (iter->doi == doi && atomic_read(&iter->refcount))

  			return iter;
  	return NULL;
  }
  
  /**
   * cipso_v4_doi_add - Add a new DOI to the CIPSO protocol engine
   * @doi_def: the DOI structure

   * @audit_info: NetLabel audit information

   *
   * Description:
   * The caller defines a new DOI for use by the CIPSO engine and calls this
   * function to add it to the list of acceptable domains.  The caller must
   * ensure that the mapping table specified in @doi_def->map meets all of the
   * requirements of the mapping type (see cipso_ipv4.h for details).  Returns
   * zero on success and non-zero on failure.
   *
   */

  int cipso_v4_doi_add(struct cipso_v4_doi *doi_def,
  		     struct netlbl_audit *audit_info)

  {

  	int ret_val = -EINVAL;

  	u32 iter;

  	u32 doi;
  	u32 doi_type;
  	struct audit_buffer *audit_buf;
  
  	doi = doi_def->doi;
  	doi_type = doi_def->type;

  	if (doi_def->doi == CIPSO_V4_DOI_UNKNOWN)

  		goto doi_add_return;

  	for (iter = 0; iter < CIPSO_V4_TAG_MAXCNT; iter++) {
  		switch (doi_def->tags[iter]) {
  		case CIPSO_V4_TAG_RBITMAP:
  			break;

  		case CIPSO_V4_TAG_RANGE:

  		case CIPSO_V4_TAG_ENUM:
  			if (doi_def->type != CIPSO_V4_MAP_PASS)

  				goto doi_add_return;

  			break;

  		case CIPSO_V4_TAG_LOCAL:
  			if (doi_def->type != CIPSO_V4_MAP_LOCAL)

  				goto doi_add_return;
  			break;
  		case CIPSO_V4_TAG_INVALID:
  			if (iter == 0)
  				goto doi_add_return;

  			break;

  		default:

  			goto doi_add_return;

  		}
  	}

  	atomic_set(&doi_def->refcount, 1);

  	spin_lock(&cipso_v4_doi_list_lock);

  	if (cipso_v4_doi_search(doi_def->doi) != NULL) {
  		spin_unlock(&cipso_v4_doi_list_lock);
  		ret_val = -EEXIST;
  		goto doi_add_return;
  	}

  	list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
  	spin_unlock(&cipso_v4_doi_list_lock);

  	ret_val = 0;
  
  doi_add_return:
  	audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_ADD, audit_info);
  	if (audit_buf != NULL) {
  		const char *type_str;
  		switch (doi_type) {
  		case CIPSO_V4_MAP_TRANS:
  			type_str = "trans";
  			break;
  		case CIPSO_V4_MAP_PASS:
  			type_str = "pass";
  			break;
  		case CIPSO_V4_MAP_LOCAL:
  			type_str = "local";
  			break;
  		default:
  			type_str = "(unknown)";
  		}
  		audit_log_format(audit_buf,
  				 " cipso_doi=%u cipso_type=%s res=%u",
  				 doi, type_str, ret_val == 0 ? 1 : 0);
  		audit_log_end(audit_buf);
  	}

  	return ret_val;

  }
  
  /**

   * cipso_v4_doi_free - Frees a DOI definition
   * @entry: the entry's RCU field
   *
   * Description:
   * This function frees all of the memory associated with a DOI definition.
   *
   */
  void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
  {
  	if (doi_def == NULL)
  		return;
  
  	switch (doi_def->type) {

  	case CIPSO_V4_MAP_TRANS:

  		kfree(doi_def->map.std->lvl.cipso);
  		kfree(doi_def->map.std->lvl.local);
  		kfree(doi_def->map.std->cat.cipso);
  		kfree(doi_def->map.std->cat.local);
  		break;
  	}
  	kfree(doi_def);
  }
  
  /**
   * cipso_v4_doi_free_rcu - Frees a DOI definition via the RCU pointer
   * @entry: the entry's RCU field
   *
   * Description:
   * This function is designed to be used as a callback to the call_rcu()
   * function so that the memory allocated to the DOI definition can be released
   * safely.
   *
   */
  static void cipso_v4_doi_free_rcu(struct rcu_head *entry)
  {
  	struct cipso_v4_doi *doi_def;
  
  	doi_def = container_of(entry, struct cipso_v4_doi, rcu);
  	cipso_v4_doi_free(doi_def);
  }
  
  /**

   * cipso_v4_doi_remove - Remove an existing DOI from the CIPSO protocol engine
   * @doi: the DOI value

   * @audit_secid: the LSM secid to use in the audit message

   *
   * Description:

   * Removes a DOI definition from the CIPSO engine.  The NetLabel routines will
   * be called to release their own LSM domain mappings as well as our own
   * domain list.  Returns zero on success and negative values on failure.

   *
   */

  int cipso_v4_doi_remove(u32 doi, struct netlbl_audit *audit_info)

  {

  	int ret_val;

  	struct cipso_v4_doi *doi_def;

  	struct audit_buffer *audit_buf;

  	spin_lock(&cipso_v4_doi_list_lock);
  	doi_def = cipso_v4_doi_search(doi);

  	if (doi_def == NULL) {

  		spin_unlock(&cipso_v4_doi_list_lock);

  		ret_val = -ENOENT;
  		goto doi_remove_return;

  	}

  	if (!atomic_dec_and_test(&doi_def->refcount)) {
  		spin_unlock(&cipso_v4_doi_list_lock);

  		ret_val = -EBUSY;
  		goto doi_remove_return;

  	}
  	list_del_rcu(&doi_def->list);

  	spin_unlock(&cipso_v4_doi_list_lock);

  	cipso_v4_cache_invalidate();
  	call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);

  	ret_val = 0;
  
  doi_remove_return:
  	audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_DEL, audit_info);
  	if (audit_buf != NULL) {
  		audit_log_format(audit_buf,
  				 " cipso_doi=%u res=%u",
  				 doi, ret_val == 0 ? 1 : 0);
  		audit_log_end(audit_buf);
  	}

  	return ret_val;

  }
  
  /**

   * cipso_v4_doi_getdef - Returns a reference to a valid DOI definition

   * @doi: the DOI value
   *
   * Description:
   * Searches for a valid DOI definition and if one is found it is returned to
   * the caller.  Otherwise NULL is returned.  The caller must ensure that

   * rcu_read_lock() is held while accessing the returned definition and the DOI
   * definition reference count is decremented when the caller is done.

   *
   */
  struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi)
  {

  	struct cipso_v4_doi *doi_def;
  
  	rcu_read_lock();
  	doi_def = cipso_v4_doi_search(doi);
  	if (doi_def == NULL)
  		goto doi_getdef_return;
  	if (!atomic_inc_not_zero(&doi_def->refcount))
  		doi_def = NULL;
  
  doi_getdef_return:
  	rcu_read_unlock();
  	return doi_def;
  }
  
  /**
   * cipso_v4_doi_putdef - Releases a reference for the given DOI definition
   * @doi_def: the DOI definition
   *
   * Description:
   * Releases a DOI definition reference obtained from cipso_v4_doi_getdef().
   *
   */
  void cipso_v4_doi_putdef(struct cipso_v4_doi *doi_def)
  {
  	if (doi_def == NULL)
  		return;
  
  	if (!atomic_dec_and_test(&doi_def->refcount))
  		return;
  	spin_lock(&cipso_v4_doi_list_lock);
  	list_del_rcu(&doi_def->list);
  	spin_unlock(&cipso_v4_doi_list_lock);
  
  	cipso_v4_cache_invalidate();
  	call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);

  }
  
  /**

   * cipso_v4_doi_walk - Iterate through the DOI definitions
   * @skip_cnt: skip past this number of DOI definitions, updated
   * @callback: callback for each DOI definition
   * @cb_arg: argument for the callback function

   *
   * Description:

   * Iterate over the DOI definition list, skipping the first @skip_cnt entries.
   * For each entry call @callback, if @callback returns a negative value stop
   * 'walking' through the list and return.  Updates the value in @skip_cnt upon
   * return.  Returns zero on success, negative values on failure.

   *
   */

  int cipso_v4_doi_walk(u32 *skip_cnt,
  		     int (*callback) (struct cipso_v4_doi *doi_def, void *arg),
  		     void *cb_arg)

  {

  	int ret_val = -ENOENT;

  	u32 doi_cnt = 0;

  	struct cipso_v4_doi *iter_doi;

  	rcu_read_lock();

  	list_for_each_entry_rcu(iter_doi, &cipso_v4_doi_list, list)

  		if (atomic_read(&iter_doi->refcount) > 0) {

  			if (doi_cnt++ < *skip_cnt)
  				continue;
  			ret_val = callback(iter_doi, cb_arg);
  			if (ret_val < 0) {
  				doi_cnt--;
  				goto doi_walk_return;

  			}

  		}

  doi_walk_return:

  	rcu_read_unlock();

  	*skip_cnt = doi_cnt;
  	return ret_val;

  }

  /*
   * Label Mapping Functions
   */
  
  /**
   * cipso_v4_map_lvl_valid - Checks to see if the given level is understood
   * @doi_def: the DOI definition
   * @level: the level to check
   *
   * Description:
   * Checks the given level against the given DOI definition and returns a
   * negative value if the level does not have a valid mapping and a zero value
   * if the level is defined by the DOI.
   *
   */
  static int cipso_v4_map_lvl_valid(const struct cipso_v4_doi *doi_def, u8 level)
  {
  	switch (doi_def->type) {
  	case CIPSO_V4_MAP_PASS:
  		return 0;

  	case CIPSO_V4_MAP_TRANS:

  		if (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL)
  			return 0;
  		break;
  	}
  
  	return -EFAULT;
  }
  
  /**
   * cipso_v4_map_lvl_hton - Perform a level mapping from the host to the network
   * @doi_def: the DOI definition
   * @host_lvl: the host MLS level
   * @net_lvl: the network/CIPSO MLS level
   *
   * Description:
   * Perform a label mapping to translate a local MLS level to the correct
   * CIPSO level using the given DOI definition.  Returns zero on success,
   * negative values otherwise.
   *
   */
  static int cipso_v4_map_lvl_hton(const struct cipso_v4_doi *doi_def,
  				 u32 host_lvl,
  				 u32 *net_lvl)
  {
  	switch (doi_def->type) {
  	case CIPSO_V4_MAP_PASS:
  		*net_lvl = host_lvl;
  		return 0;

  	case CIPSO_V4_MAP_TRANS:

  		if (host_lvl < doi_def->map.std->lvl.local_size &&
  		    doi_def->map.std->lvl.local[host_lvl] < CIPSO_V4_INV_LVL) {

  			*net_lvl = doi_def->map.std->lvl.local[host_lvl];
  			return 0;
  		}

  		return -EPERM;

  	}
  
  	return -EINVAL;
  }
  
  /**
   * cipso_v4_map_lvl_ntoh - Perform a level mapping from the network to the host
   * @doi_def: the DOI definition
   * @net_lvl: the network/CIPSO MLS level
   * @host_lvl: the host MLS level
   *
   * Description:
   * Perform a label mapping to translate a CIPSO level to the correct local MLS
   * level using the given DOI definition.  Returns zero on success, negative
   * values otherwise.
   *
   */
  static int cipso_v4_map_lvl_ntoh(const struct cipso_v4_doi *doi_def,
  				 u32 net_lvl,
  				 u32 *host_lvl)
  {
  	struct cipso_v4_std_map_tbl *map_tbl;
  
  	switch (doi_def->type) {
  	case CIPSO_V4_MAP_PASS:
  		*host_lvl = net_lvl;
  		return 0;

  	case CIPSO_V4_MAP_TRANS:

  		map_tbl = doi_def->map.std;
  		if (net_lvl < map_tbl->lvl.cipso_size &&
  		    map_tbl->lvl.cipso[net_lvl] < CIPSO_V4_INV_LVL) {
  			*host_lvl = doi_def->map.std->lvl.cipso[net_lvl];
  			return 0;
  		}

  		return -EPERM;

  	}
  
  	return -EINVAL;
  }
  
  /**
   * cipso_v4_map_cat_rbm_valid - Checks to see if the category bitmap is valid
   * @doi_def: the DOI definition
   * @bitmap: category bitmap
   * @bitmap_len: bitmap length in bytes
   *
   * Description:
   * Checks the given category bitmap against the given DOI definition and
   * returns a negative value if any of the categories in the bitmap do not have
   * a valid mapping and a zero value if all of the categories are valid.
   *
   */
  static int cipso_v4_map_cat_rbm_valid(const struct cipso_v4_doi *doi_def,
  				      const unsigned char *bitmap,
  				      u32 bitmap_len)
  {
  	int cat = -1;
  	u32 bitmap_len_bits = bitmap_len * 8;

  	u32 cipso_cat_size;
  	u32 *cipso_array;

  
  	switch (doi_def->type) {
  	case CIPSO_V4_MAP_PASS:
  		return 0;

  	case CIPSO_V4_MAP_TRANS:

  		cipso_cat_size = doi_def->map.std->cat.cipso_size;
  		cipso_array = doi_def->map.std->cat.cipso;

  		for (;;) {
  			cat = cipso_v4_bitmap_walk(bitmap,
  						   bitmap_len_bits,
  						   cat + 1,
  						   1);
  			if (cat < 0)
  				break;
  			if (cat >= cipso_cat_size ||
  			    cipso_array[cat] >= CIPSO_V4_INV_CAT)
  				return -EFAULT;
  		}
  
  		if (cat == -1)
  			return 0;
  		break;
  	}
  
  	return -EFAULT;
  }
  
  /**
   * cipso_v4_map_cat_rbm_hton - Perform a category mapping from host to network
   * @doi_def: the DOI definition

   * @secattr: the security attributes

   * @net_cat: the zero'd out category bitmap in network/CIPSO format
   * @net_cat_len: the length of the CIPSO bitmap in bytes
   *
   * Description:
   * Perform a label mapping to translate a local MLS category bitmap to the
   * correct CIPSO bitmap using the given DOI definition.  Returns the minimum
   * size in bytes of the network bitmap on success, negative values otherwise.
   *
   */
  static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,

  				     const struct netlbl_lsm_secattr *secattr,

  				     unsigned char *net_cat,
  				     u32 net_cat_len)
  {
  	int host_spot = -1;

  	u32 net_spot = CIPSO_V4_INV_CAT;

  	u32 net_spot_max = 0;

  	u32 net_clen_bits = net_cat_len * 8;

  	u32 host_cat_size = 0;
  	u32 *host_cat_array = NULL;

  	if (doi_def->type == CIPSO_V4_MAP_TRANS) {

  		host_cat_size = doi_def->map.std->cat.local_size;
  		host_cat_array = doi_def->map.std->cat.local;

  	}
  
  	for (;;) {

  		host_spot = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,

  						       host_spot + 1);
  		if (host_spot < 0)
  			break;
  
  		switch (doi_def->type) {
  		case CIPSO_V4_MAP_PASS:
  			net_spot = host_spot;
  			break;

  		case CIPSO_V4_MAP_TRANS:

  			if (host_spot >= host_cat_size)
  				return -EPERM;

  			net_spot = host_cat_array[host_spot];

  			if (net_spot >= CIPSO_V4_INV_CAT)
  				return -EPERM;

  			break;

  		}

  		if (net_spot >= net_clen_bits)
  			return -ENOSPC;
  		cipso_v4_bitmap_setbit(net_cat, net_spot, 1);

  		if (net_spot > net_spot_max)
  			net_spot_max = net_spot;

  	}

  	if (++net_spot_max % 8)
  		return net_spot_max / 8 + 1;
  	return net_spot_max / 8;

  }
  
  /**
   * cipso_v4_map_cat_rbm_ntoh - Perform a category mapping from network to host
   * @doi_def: the DOI definition
   * @net_cat: the category bitmap in network/CIPSO format
   * @net_cat_len: the length of the CIPSO bitmap in bytes

   * @secattr: the security attributes

   *
   * Description:
   * Perform a label mapping to translate a CIPSO bitmap to the correct local

   * MLS category bitmap using the given DOI definition.  Returns zero on
   * success, negative values on failure.

   *
   */
  static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
  				     const unsigned char *net_cat,
  				     u32 net_cat_len,

  				     struct netlbl_lsm_secattr *secattr)

  {

  	int ret_val;

  	int net_spot = -1;

  	u32 host_spot = CIPSO_V4_INV_CAT;

  	u32 net_clen_bits = net_cat_len * 8;

  	u32 net_cat_size = 0;
  	u32 *net_cat_array = NULL;

  	if (doi_def->type == CIPSO_V4_MAP_TRANS) {

  		net_cat_size = doi_def->map.std->cat.cipso_size;
  		net_cat_array = doi_def->map.std->cat.cipso;

  	}

  	for (;;) {
  		net_spot = cipso_v4_bitmap_walk(net_cat,
  						net_clen_bits,
  						net_spot + 1,
  						1);
  		if (net_spot < 0) {
  			if (net_spot == -2)
  				return -EFAULT;
  			return 0;
  		}
  
  		switch (doi_def->type) {
  		case CIPSO_V4_MAP_PASS:
  			host_spot = net_spot;
  			break;

  		case CIPSO_V4_MAP_TRANS:

  			if (net_spot >= net_cat_size)
  				return -EPERM;

  			host_spot = net_cat_array[net_spot];

  			if (host_spot >= CIPSO_V4_INV_CAT)
  				return -EPERM;

  			break;

  		}

  		ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,

  						       host_spot,
  						       GFP_ATOMIC);
  		if (ret_val != 0)
  			return ret_val;

  	}
  
  	return -EINVAL;
  }

  /**
   * cipso_v4_map_cat_enum_valid - Checks to see if the categories are valid
   * @doi_def: the DOI definition
   * @enumcat: category list
   * @enumcat_len: length of the category list in bytes
   *
   * Description:
   * Checks the given categories against the given DOI definition and returns a
   * negative value if any of the categories do not have a valid mapping and a
   * zero value if all of the categories are valid.
   *
   */
  static int cipso_v4_map_cat_enum_valid(const struct cipso_v4_doi *doi_def,
  				       const unsigned char *enumcat,
  				       u32 enumcat_len)
  {
  	u16 cat;
  	int cat_prev = -1;
  	u32 iter;
  
  	if (doi_def->type != CIPSO_V4_MAP_PASS || enumcat_len & 0x01)
  		return -EFAULT;
  
  	for (iter = 0; iter < enumcat_len; iter += 2) {

  		cat = get_unaligned_be16(&enumcat[iter]);

  		if (cat <= cat_prev)
  			return -EFAULT;
  		cat_prev = cat;
  	}
  
  	return 0;
  }
  
  /**
   * cipso_v4_map_cat_enum_hton - Perform a category mapping from host to network
   * @doi_def: the DOI definition
   * @secattr: the security attributes
   * @net_cat: the zero'd out category list in network/CIPSO format
   * @net_cat_len: the length of the CIPSO category list in bytes
   *
   * Description:
   * Perform a label mapping to translate a local MLS category bitmap to the
   * correct CIPSO category list using the given DOI definition.   Returns the
   * size in bytes of the network category bitmap on success, negative values
   * otherwise.
   *
   */
  static int cipso_v4_map_cat_enum_hton(const struct cipso_v4_doi *doi_def,
  				      const struct netlbl_lsm_secattr *secattr,
  				      unsigned char *net_cat,
  				      u32 net_cat_len)
  {
  	int cat = -1;
  	u32 cat_iter = 0;
  
  	for (;;) {

  		cat = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
  						 cat + 1);

  		if (cat < 0)
  			break;
  		if ((cat_iter + 2) > net_cat_len)
  			return -ENOSPC;
  
  		*((__be16 *)&net_cat[cat_iter]) = htons(cat);
  		cat_iter += 2;
  	}
  
  	return cat_iter;
  }
  
  /**
   * cipso_v4_map_cat_enum_ntoh - Perform a category mapping from network to host
   * @doi_def: the DOI definition
   * @net_cat: the category list in network/CIPSO format
   * @net_cat_len: the length of the CIPSO bitmap in bytes
   * @secattr: the security attributes
   *
   * Description:
   * Perform a label mapping to translate a CIPSO category list to the correct
   * local MLS category bitmap using the given DOI definition.  Returns zero on
   * success, negative values on failure.
   *
   */
  static int cipso_v4_map_cat_enum_ntoh(const struct cipso_v4_doi *doi_def,
  				      const unsigned char *net_cat,
  				      u32 net_cat_len,
  				      struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  	u32 iter;
  
  	for (iter = 0; iter < net_cat_len; iter += 2) {

  		ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,

  				get_unaligned_be16(&net_cat[iter]),

  				GFP_ATOMIC);

  		if (ret_val != 0)
  			return ret_val;
  	}
  
  	return 0;
  }

  /**
   * cipso_v4_map_cat_rng_valid - Checks to see if the categories are valid
   * @doi_def: the DOI definition
   * @rngcat: category list
   * @rngcat_len: length of the category list in bytes
   *
   * Description:
   * Checks the given categories against the given DOI definition and returns a
   * negative value if any of the categories do not have a valid mapping and a
   * zero value if all of the categories are valid.
   *
   */
  static int cipso_v4_map_cat_rng_valid(const struct cipso_v4_doi *doi_def,
  				      const unsigned char *rngcat,
  				      u32 rngcat_len)
  {
  	u16 cat_high;
  	u16 cat_low;
  	u32 cat_prev = CIPSO_V4_MAX_REM_CATS + 1;
  	u32 iter;
  
  	if (doi_def->type != CIPSO_V4_MAP_PASS || rngcat_len & 0x01)
  		return -EFAULT;
  
  	for (iter = 0; iter < rngcat_len; iter += 4) {

  		cat_high = get_unaligned_be16(&rngcat[iter]);

  		if ((iter + 4) <= rngcat_len)

  			cat_low = get_unaligned_be16(&rngcat[iter + 2]);

  		else
  			cat_low = 0;
  
  		if (cat_high > cat_prev)
  			return -EFAULT;
  
  		cat_prev = cat_low;
  	}
  
  	return 0;
  }
  
  /**
   * cipso_v4_map_cat_rng_hton - Perform a category mapping from host to network
   * @doi_def: the DOI definition
   * @secattr: the security attributes
   * @net_cat: the zero'd out category list in network/CIPSO format
   * @net_cat_len: the length of the CIPSO category list in bytes
   *
   * Description:
   * Perform a label mapping to translate a local MLS category bitmap to the
   * correct CIPSO category list using the given DOI definition.   Returns the
   * size in bytes of the network category bitmap on success, negative values
   * otherwise.
   *
   */
  static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def,
  				     const struct netlbl_lsm_secattr *secattr,
  				     unsigned char *net_cat,
  				     u32 net_cat_len)
  {

  	int iter = -1;

  	u16 array[CIPSO_V4_TAG_RNG_CAT_MAX * 2];

  	u32 array_cnt = 0;
  	u32 cat_size = 0;

  	/* make sure we don't overflow the 'array[]' variable */

  	if (net_cat_len >
  	    (CIPSO_V4_OPT_LEN_MAX - CIPSO_V4_HDR_LEN - CIPSO_V4_TAG_RNG_BLEN))
  		return -ENOSPC;

  
  	for (;;) {

  		iter = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
  						  iter + 1);

  		if (iter < 0)
  			break;
  		cat_size += (iter == 0 ? 0 : sizeof(u16));
  		if (cat_size > net_cat_len)
  			return -ENOSPC;
  		array[array_cnt++] = iter;

  		iter = netlbl_secattr_catmap_walk_rng(secattr->attr.mls.cat,
  						      iter);

  		if (iter < 0)
  			return -EFAULT;
  		cat_size += sizeof(u16);
  		if (cat_size > net_cat_len)
  			return -ENOSPC;
  		array[array_cnt++] = iter;
  	}
  
  	for (iter = 0; array_cnt > 0;) {
  		*((__be16 *)&net_cat[iter]) = htons(array[--array_cnt]);
  		iter += 2;
  		array_cnt--;
  		if (array[array_cnt] != 0) {
  			*((__be16 *)&net_cat[iter]) = htons(array[array_cnt]);
  			iter += 2;
  		}
  	}
  
  	return cat_size;
  }
  
  /**
   * cipso_v4_map_cat_rng_ntoh - Perform a category mapping from network to host
   * @doi_def: the DOI definition
   * @net_cat: the category list in network/CIPSO format
   * @net_cat_len: the length of the CIPSO bitmap in bytes
   * @secattr: the security attributes
   *
   * Description:
   * Perform a label mapping to translate a CIPSO category list to the correct
   * local MLS category bitmap using the given DOI definition.  Returns zero on
   * success, negative values on failure.
   *
   */
  static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def,
  				     const unsigned char *net_cat,
  				     u32 net_cat_len,
  				     struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  	u32 net_iter;
  	u16 cat_low;
  	u16 cat_high;

  	for (net_iter = 0; net_iter < net_cat_len; net_iter += 4) {

  		cat_high = get_unaligned_be16(&net_cat[net_iter]);

  		if ((net_iter + 4) <= net_cat_len)

  			cat_low = get_unaligned_be16(&net_cat[net_iter + 2]);

  		else
  			cat_low = 0;

  		ret_val = netlbl_secattr_catmap_setrng(secattr->attr.mls.cat,

  						       cat_low,
  						       cat_high,
  						       GFP_ATOMIC);
  		if (ret_val != 0)
  			return ret_val;
  	}
  
  	return 0;
  }

  /*
   * Protocol Handling Functions
   */

  /**
   * cipso_v4_gentag_hdr - Generate a CIPSO option header
   * @doi_def: the DOI definition

   * @len: the total tag length in bytes, not including this header

   * @buf: the CIPSO option buffer
   *
   * Description:

   * Write a CIPSO header into the beginning of @buffer.

   *
   */

  static void cipso_v4_gentag_hdr(const struct cipso_v4_doi *doi_def,
  				unsigned char *buf,
  				u32 len)

  {

  	buf[0] = IPOPT_CIPSO;
  	buf[1] = CIPSO_V4_HDR_LEN + len;

  	*(__be32 *)&buf[2] = htonl(doi_def->doi);

  }

  /**
   * cipso_v4_gentag_rbm - Generate a CIPSO restricted bitmap tag (type #1)
   * @doi_def: the DOI definition
   * @secattr: the security attributes
   * @buffer: the option buffer
   * @buffer_len: length of buffer in bytes
   *
   * Description:
   * Generate a CIPSO option using the restricted bitmap tag, tag type #1.  The
   * actual buffer length may be larger than the indicated size due to

   * translation between host and network category bitmaps.  Returns the size of
   * the tag on success, negative values on failure.

   *
   */
  static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
  			       const struct netlbl_lsm_secattr *secattr,

  			       unsigned char *buffer,
  			       u32 buffer_len)

  {

  	int ret_val;

  	u32 tag_len;

  	u32 level;

  	if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
  		return -EPERM;

  	ret_val = cipso_v4_map_lvl_hton(doi_def,
  					secattr->attr.mls.lvl,
  					&level);

  	if (ret_val != 0)
  		return ret_val;

  	if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {

  		ret_val = cipso_v4_map_cat_rbm_hton(doi_def,

  						    secattr,

  						    &buffer[4],
  						    buffer_len - 4);

  		if (ret_val < 0)

  			return ret_val;

  
  		/* This will send packets using the "optimized" format when

  		 * possible as specified in  section 3.4.2.6 of the

  		 * CIPSO draft. */

  		if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)

  			tag_len = 14;

  		else

  			tag_len = 4 + ret_val;
  	} else
  		tag_len = 4;

  	buffer[0] = CIPSO_V4_TAG_RBITMAP;

  	buffer[1] = tag_len;
  	buffer[3] = level;

  	return tag_len;

  }
  
  /**
   * cipso_v4_parsetag_rbm - Parse a CIPSO restricted bitmap tag
   * @doi_def: the DOI definition
   * @tag: the CIPSO tag
   * @secattr: the security attributes
   *
   * Description:
   * Parse a CIPSO restricted bitmap tag (tag type #1) and return the security
   * attributes in @secattr.  Return zero on success, negatives values on
   * failure.
   *
   */
  static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
  				 const unsigned char *tag,
  				 struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  	u8 tag_len = tag[1];
  	u32 level;
  
  	ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
  	if (ret_val != 0)
  		return ret_val;

  	secattr->attr.mls.lvl = level;

  	secattr->flags |= NETLBL_SECATTR_MLS_LVL;

  
  	if (tag_len > 4) {

  		secattr->attr.mls.cat =
  		                       netlbl_secattr_catmap_alloc(GFP_ATOMIC);
  		if (secattr->attr.mls.cat == NULL)

  			return -ENOMEM;
  
  		ret_val = cipso_v4_map_cat_rbm_ntoh(doi_def,
  						    &tag[4],
  						    tag_len - 4,

  						    secattr);
  		if (ret_val != 0) {

  			netlbl_secattr_catmap_free(secattr->attr.mls.cat);

  			return ret_val;
  		}

  
  		secattr->flags |= NETLBL_SECATTR_MLS_CAT;

  	}
  
  	return 0;
  }
  
  /**

   * cipso_v4_gentag_enum - Generate a CIPSO enumerated tag (type #2)
   * @doi_def: the DOI definition
   * @secattr: the security attributes
   * @buffer: the option buffer
   * @buffer_len: length of buffer in bytes
   *
   * Description:
   * Generate a CIPSO option using the enumerated tag, tag type #2.  Returns the
   * size of the tag on success, negative values on failure.
   *
   */
  static int cipso_v4_gentag_enum(const struct cipso_v4_doi *doi_def,
  				const struct netlbl_lsm_secattr *secattr,
  				unsigned char *buffer,
  				u32 buffer_len)
  {
  	int ret_val;
  	u32 tag_len;
  	u32 level;
  
  	if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
  		return -EPERM;

  	ret_val = cipso_v4_map_lvl_hton(doi_def,
  					secattr->attr.mls.lvl,
  					&level);

  	if (ret_val != 0)
  		return ret_val;
  
  	if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
  		ret_val = cipso_v4_map_cat_enum_hton(doi_def,
  						     secattr,
  						     &buffer[4],
  						     buffer_len - 4);
  		if (ret_val < 0)
  			return ret_val;
  
  		tag_len = 4 + ret_val;
  	} else
  		tag_len = 4;

  	buffer[0] = CIPSO_V4_TAG_ENUM;

  	buffer[1] = tag_len;
  	buffer[3] = level;
  
  	return tag_len;
  }
  
  /**
   * cipso_v4_parsetag_enum - Parse a CIPSO enumerated tag
   * @doi_def: the DOI definition
   * @tag: the CIPSO tag
   * @secattr: the security attributes
   *
   * Description:
   * Parse a CIPSO enumerated tag (tag type #2) and return the security
   * attributes in @secattr.  Return zero on success, negatives values on
   * failure.
   *
   */
  static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
  				  const unsigned char *tag,
  				  struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  	u8 tag_len = tag[1];
  	u32 level;
  
  	ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
  	if (ret_val != 0)
  		return ret_val;

  	secattr->attr.mls.lvl = level;

  	secattr->flags |= NETLBL_SECATTR_MLS_LVL;
  
  	if (tag_len > 4) {

  		secattr->attr.mls.cat =
  			               netlbl_secattr_catmap_alloc(GFP_ATOMIC);
  		if (secattr->attr.mls.cat == NULL)

  			return -ENOMEM;
  
  		ret_val = cipso_v4_map_cat_enum_ntoh(doi_def,
  						     &tag[4],
  						     tag_len - 4,
  						     secattr);
  		if (ret_val != 0) {

  			netlbl_secattr_catmap_free(secattr->attr.mls.cat);

  			return ret_val;
  		}
  
  		secattr->flags |= NETLBL_SECATTR_MLS_CAT;
  	}
  
  	return 0;
  }
  
  /**

   * cipso_v4_gentag_rng - Generate a CIPSO ranged tag (type #5)
   * @doi_def: the DOI definition
   * @secattr: the security attributes
   * @buffer: the option buffer
   * @buffer_len: length of buffer in bytes
   *
   * Description:
   * Generate a CIPSO option using the ranged tag, tag type #5.  Returns the
   * size of the tag on success, negative values on failure.
   *
   */
  static int cipso_v4_gentag_rng(const struct cipso_v4_doi *doi_def,
  			       const struct netlbl_lsm_secattr *secattr,
  			       unsigned char *buffer,
  			       u32 buffer_len)
  {
  	int ret_val;
  	u32 tag_len;
  	u32 level;
  
  	if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
  		return -EPERM;

  	ret_val = cipso_v4_map_lvl_hton(doi_def,
  					secattr->attr.mls.lvl,
  					&level);

  	if (ret_val != 0)
  		return ret_val;
  
  	if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
  		ret_val = cipso_v4_map_cat_rng_hton(doi_def,
  						    secattr,
  						    &buffer[4],
  						    buffer_len - 4);
  		if (ret_val < 0)
  			return ret_val;
  
  		tag_len = 4 + ret_val;
  	} else
  		tag_len = 4;

  	buffer[0] = CIPSO_V4_TAG_RANGE;

  	buffer[1] = tag_len;
  	buffer[3] = level;
  
  	return tag_len;
  }
  
  /**
   * cipso_v4_parsetag_rng - Parse a CIPSO ranged tag
   * @doi_def: the DOI definition
   * @tag: the CIPSO tag
   * @secattr: the security attributes
   *
   * Description:
   * Parse a CIPSO ranged tag (tag type #5) and return the security attributes
   * in @secattr.  Return zero on success, negatives values on failure.
   *
   */
  static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
  				 const unsigned char *tag,
  				 struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  	u8 tag_len = tag[1];
  	u32 level;
  
  	ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
  	if (ret_val != 0)
  		return ret_val;

  	secattr->attr.mls.lvl = level;

  	secattr->flags |= NETLBL_SECATTR_MLS_LVL;
  
  	if (tag_len > 4) {

  		secattr->attr.mls.cat =
  			               netlbl_secattr_catmap_alloc(GFP_ATOMIC);
  		if (secattr->attr.mls.cat == NULL)

  			return -ENOMEM;
  
  		ret_val = cipso_v4_map_cat_rng_ntoh(doi_def,
  						    &tag[4],
  						    tag_len - 4,
  						    secattr);
  		if (ret_val != 0) {

  			netlbl_secattr_catmap_free(secattr->attr.mls.cat);

  			return ret_val;
  		}
  
  		secattr->flags |= NETLBL_SECATTR_MLS_CAT;
  	}
  
  	return 0;
  }
  
  /**

   * cipso_v4_gentag_loc - Generate a CIPSO local tag (non-standard)
   * @doi_def: the DOI definition
   * @secattr: the security attributes
   * @buffer: the option buffer
   * @buffer_len: length of buffer in bytes
   *
   * Description:
   * Generate a CIPSO option using the local tag.  Returns the size of the tag
   * on success, negative values on failure.
   *
   */
  static int cipso_v4_gentag_loc(const struct cipso_v4_doi *doi_def,
  			       const struct netlbl_lsm_secattr *secattr,
  			       unsigned char *buffer,
  			       u32 buffer_len)
  {
  	if (!(secattr->flags & NETLBL_SECATTR_SECID))
  		return -EPERM;
  
  	buffer[0] = CIPSO_V4_TAG_LOCAL;
  	buffer[1] = CIPSO_V4_TAG_LOC_BLEN;
  	*(u32 *)&buffer[2] = secattr->attr.secid;
  
  	return CIPSO_V4_TAG_LOC_BLEN;
  }
  
  /**
   * cipso_v4_parsetag_loc - Parse a CIPSO local tag
   * @doi_def: the DOI definition
   * @tag: the CIPSO tag
   * @secattr: the security attributes
   *
   * Description:
   * Parse a CIPSO local tag and return the security attributes in @secattr.
   * Return zero on success, negatives values on failure.
   *
   */
  static int cipso_v4_parsetag_loc(const struct cipso_v4_doi *doi_def,
  				 const unsigned char *tag,
  				 struct netlbl_lsm_secattr *secattr)
  {
  	secattr->attr.secid = *(u32 *)&tag[2];
  	secattr->flags |= NETLBL_SECATTR_SECID;
  
  	return 0;
  }
  
  /**

   * cipso_v4_validate - Validate a CIPSO option
   * @option: the start of the option, on error it is set to point to the error
   *
   * Description:
   * This routine is called to validate a CIPSO option, it checks all of the
   * fields to ensure that they are at least valid, see the draft snippet below
   * for details.  If the option is valid then a zero value is returned and
   * the value of @option is unchanged.  If the option is invalid then a
   * non-zero value is returned and @option is adjusted to point to the
   * offending portion of the option.  From the IETF draft ...
   *
   *  "If any field within the CIPSO options, such as the DOI identifier, is not
   *   recognized the IP datagram is discarded and an ICMP 'parameter problem'
   *   (type 12) is generated and returned.  The ICMP code field is set to 'bad
   *   parameter' (code 0) and the pointer is set to the start of the CIPSO field
   *   that is unrecognized."
   *
   */

  int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)

  {
  	unsigned char *opt = *option;
  	unsigned char *tag;
  	unsigned char opt_iter;
  	unsigned char err_offset = 0;
  	u8 opt_len;
  	u8 tag_len;
  	struct cipso_v4_doi *doi_def = NULL;
  	u32 tag_iter;
  
  	/* caller already checks for length values that are too large */
  	opt_len = opt[1];
  	if (opt_len < 8) {
  		err_offset = 1;
  		goto validate_return;
  	}
  
  	rcu_read_lock();

  	doi_def = cipso_v4_doi_search(get_unaligned_be32(&opt[2]));

  	if (doi_def == NULL) {
  		err_offset = 2;
  		goto validate_return_locked;
  	}

  	opt_iter = CIPSO_V4_HDR_LEN;

  	tag = opt + opt_iter;
  	while (opt_iter < opt_len) {
  		for (tag_iter = 0; doi_def->tags[tag_iter] != tag[0];)
  			if (doi_def->tags[tag_iter] == CIPSO_V4_TAG_INVALID ||
  			    ++tag_iter == CIPSO_V4_TAG_MAXCNT) {
  				err_offset = opt_iter;
  				goto validate_return_locked;
  			}
  
  		tag_len = tag[1];
  		if (tag_len > (opt_len - opt_iter)) {
  			err_offset = opt_iter + 1;
  			goto validate_return_locked;
  		}
  
  		switch (tag[0]) {
  		case CIPSO_V4_TAG_RBITMAP:

  			if (tag_len < CIPSO_V4_TAG_RBM_BLEN) {

  				err_offset = opt_iter + 1;
  				goto validate_return_locked;
  			}
  
  			/* We are already going to do all the verification
  			 * necessary at the socket layer so from our point of
  			 * view it is safe to turn these checks off (and less
  			 * work), however, the CIPSO draft says we should do
  			 * all the CIPSO validations here but it doesn't
  			 * really specify _exactly_ what we need to validate
  			 * ... so, just make it a sysctl tunable. */
  			if (cipso_v4_rbm_strictvalid) {
  				if (cipso_v4_map_lvl_valid(doi_def,
  							   tag[3]) < 0) {
  					err_offset = opt_iter + 3;
  					goto validate_return_locked;
  				}

  				if (tag_len > CIPSO_V4_TAG_RBM_BLEN &&

  				    cipso_v4_map_cat_rbm_valid(doi_def,
  							    &tag[4],
  							    tag_len - 4) < 0) {
  					err_offset = opt_iter + 4;
  					goto validate_return_locked;
  				}
  			}
  			break;

  		case CIPSO_V4_TAG_ENUM:

  			if (tag_len < CIPSO_V4_TAG_ENUM_BLEN) {

  				err_offset = opt_iter + 1;
  				goto validate_return_locked;
  			}
  
  			if (cipso_v4_map_lvl_valid(doi_def,
  						   tag[3]) < 0) {
  				err_offset = opt_iter + 3;
  				goto validate_return_locked;
  			}

  			if (tag_len > CIPSO_V4_TAG_ENUM_BLEN &&

  			    cipso_v4_map_cat_enum_valid(doi_def,
  							&tag[4],
  							tag_len - 4) < 0) {
  				err_offset = opt_iter + 4;
  				goto validate_return_locked;
  			}
  			break;

  		case CIPSO_V4_TAG_RANGE:

  			if (tag_len < CIPSO_V4_TAG_RNG_BLEN) {

  				err_offset = opt_iter + 1;
  				goto validate_return_locked;
  			}
  
  			if (cipso_v4_map_lvl_valid(doi_def,
  						   tag[3]) < 0) {
  				err_offset = opt_iter + 3;
  				goto validate_return_locked;
  			}

  			if (tag_len > CIPSO_V4_TAG_RNG_BLEN &&

  			    cipso_v4_map_cat_rng_valid(doi_def,
  						       &tag[4],
  						       tag_len - 4) < 0) {
  				err_offset = opt_iter + 4;
  				goto validate_return_locked;
  			}
  			break;

  		case CIPSO_V4_TAG_LOCAL:
  			/* This is a non-standard tag that we only allow for
  			 * local connections, so if the incoming interface is
  			 * not the loopback device drop the packet. */
  			if (!(skb->dev->flags & IFF_LOOPBACK)) {
  				err_offset = opt_iter;
  				goto validate_return_locked;
  			}
  			if (tag_len != CIPSO_V4_TAG_LOC_BLEN) {
  				err_offset = opt_iter + 1;
  				goto validate_return_locked;
  			}
  			break;

  		default:
  			err_offset = opt_iter;
  			goto validate_return_locked;
  		}
  
  		tag += tag_len;
  		opt_iter += tag_len;
  	}
  
  validate_return_locked:
  	rcu_read_unlock();
  validate_return:
  	*option = opt + err_offset;
  	return err_offset;
  }
  
  /**

   * cipso_v4_error - Send the correct response for a bad packet

   * @skb: the packet
   * @error: the error code
   * @gateway: CIPSO gateway flag
   *
   * Description:
   * Based on the error code given in @error, send an ICMP error message back to
   * the originating host.  From the IETF draft ...
   *
   *  "If the contents of the CIPSO [option] are valid but the security label is
   *   outside of the configured host or port label range, the datagram is
   *   discarded and an ICMP 'destination unreachable' (type 3) is generated and
   *   returned.  The code field of the ICMP is set to 'communication with
   *   destination network administratively prohibited' (code 9) or to
   *   'communication with destination host administratively prohibited'
   *   (code 10).  The value of the code is dependent on whether the originator
   *   of the ICMP message is acting as a CIPSO host or a CIPSO gateway.  The
   *   recipient of the ICMP message MUST be able to handle either value.  The
   *   same procedure is performed if a CIPSO [option] can not be added to an
   *   IP packet because it is too large to fit in the IP options area."
   *
   *  "If the error is triggered by receipt of an ICMP message, the message is
   *   discarded and no response is permitted (consistent with general ICMP
   *   processing rules)."
   *
   */
  void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
  {

  	if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)

  		return;
  
  	if (gateway)
  		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0);
  	else
  		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0);
  }
  
  /**

   * cipso_v4_genopt - Generate a CIPSO option
   * @buf: the option buffer
   * @buf_len: the size of opt_buf

   * @doi_def: the CIPSO DOI to use

   * @secattr: the security attributes

   *
   * Description:

   * Generate a CIPSO option using the DOI definition and security attributes
   * passed to the function.  Returns the length of the option on success and
   * negative values on failure.

   *
   */

  static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
  			   const struct cipso_v4_doi *doi_def,
  			   const struct netlbl_lsm_secattr *secattr)

  {

  	int ret_val;

  	u32 iter;

  	if (buf_len <= CIPSO_V4_HDR_LEN)
  		return -ENOSPC;

  	/* XXX - This code assumes only one tag per CIPSO option which isn't
  	 * really a good assumption to make but since we only support the MAC
  	 * tags right now it is a safe assumption. */
  	iter = 0;
  	do {

  		memset(buf, 0, buf_len);

  		switch (doi_def->tags[iter]) {
  		case CIPSO_V4_TAG_RBITMAP:
  			ret_val = cipso_v4_gentag_rbm(doi_def,

  						   secattr,
  						   &buf[CIPSO_V4_HDR_LEN],
  						   buf_len - CIPSO_V4_HDR_LEN);

  			break;

  		case CIPSO_V4_TAG_ENUM:
  			ret_val = cipso_v4_gentag_enum(doi_def,
  						   secattr,
  						   &buf[CIPSO_V4_HDR_LEN],
  						   buf_len - CIPSO_V4_HDR_LEN);
  			break;

  		case CIPSO_V4_TAG_RANGE:
  			ret_val = cipso_v4_gentag_rng(doi_def,
  						   secattr,
  						   &buf[CIPSO_V4_HDR_LEN],
  						   buf_len - CIPSO_V4_HDR_LEN);
  			break;

  		case CIPSO_V4_TAG_LOCAL:
  			ret_val = cipso_v4_gentag_loc(doi_def,
  						   secattr,
  						   &buf[CIPSO_V4_HDR_LEN],
  						   buf_len - CIPSO_V4_HDR_LEN);
  			break;

  		default:

  			return -EPERM;

  		}
  
  		iter++;

  	} while (ret_val < 0 &&

  		 iter < CIPSO_V4_TAG_MAXCNT &&
  		 doi_def->tags[iter] != CIPSO_V4_TAG_INVALID);

  	if (ret_val < 0)

  		return ret_val;

  	cipso_v4_gentag_hdr(doi_def, buf, ret_val);

  	return CIPSO_V4_HDR_LEN + ret_val;
  }

  static void opt_kfree_rcu(struct rcu_head *head)
  {
  	kfree(container_of(head, struct ip_options_rcu, rcu));
  }

  /**
   * cipso_v4_sock_setattr - Add a CIPSO option to a socket
   * @sk: the socket
   * @doi_def: the CIPSO DOI to use
   * @secattr: the specific security attributes of the socket
   *
   * Description:
   * Set the CIPSO option on the given socket using the DOI definition and
   * security attributes passed to the function.  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 and negative
   * values on failure.
   *
   */
  int cipso_v4_sock_setattr(struct sock *sk,
  			  const struct cipso_v4_doi *doi_def,
  			  const struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val = -EPERM;
  	unsigned char *buf = NULL;
  	u32 buf_len;
  	u32 opt_len;

  	struct ip_options_rcu *old, *opt = NULL;

  	struct inet_sock *sk_inet;
  	struct inet_connection_sock *sk_conn;
  
  	/* In the case of sock_create_lite(), the sock->sk field is not
  	 * defined yet but it is not a problem as the only users of these
  	 * "lite" PF_INET sockets are functions which do an accept() call
  	 * afterwards so we will label the socket as part of the accept(). */
  	if (sk == NULL)
  		return 0;
  
  	/* We allocate the maximum CIPSO option size here so we are probably
  	 * being a little wasteful, but it makes our life _much_ easier later
  	 * on and after all we are only talking about 40 bytes. */
  	buf_len = CIPSO_V4_OPT_LEN_MAX;
  	buf = kmalloc(buf_len, GFP_ATOMIC);
  	if (buf == NULL) {
  		ret_val = -ENOMEM;
  		goto socket_setattr_failure;
  	}
  
  	ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
  	if (ret_val < 0)
  		goto socket_setattr_failure;
  	buf_len = ret_val;

  
  	/* We can't use ip_options_get() directly because it makes a call to
  	 * ip_options_get_alloc() which allocates memory with GFP_KERNEL and

  	 * we won't always have CAP_NET_RAW even though we _always_ want to
  	 * set the IPOPT_CIPSO option. */

  	opt_len = (buf_len + 3) & ~3;
  	opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
  	if (opt == NULL) {
  		ret_val = -ENOMEM;
  		goto socket_setattr_failure;
  	}

  	memcpy(opt->opt.__data, buf, buf_len);
  	opt->opt.optlen = opt_len;
  	opt->opt.cipso = sizeof(struct iphdr);

  	kfree(buf);
  	buf = NULL;

  
  	sk_inet = inet_sk(sk);

  
  	old = rcu_dereference_protected(sk_inet->inet_opt, sock_owned_by_user(sk));

  	if (sk_inet->is_icsk) {
  		sk_conn = inet_csk(sk);

  		if (old)
  			sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
  		sk_conn->icsk_ext_hdr_len += opt->opt.optlen;

  		sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
  	}

  	rcu_assign_pointer(sk_inet->inet_opt, opt);
  	if (old)
  		call_rcu(&old->rcu, opt_kfree_rcu);

  
  	return 0;
  
  socket_setattr_failure:
  	kfree(buf);
  	kfree(opt);
  	return ret_val;
  }
  
  /**

   * cipso_v4_req_setattr - Add a CIPSO option to a connection request socket
   * @req: the connection request socket
   * @doi_def: the CIPSO DOI to use
   * @secattr: the specific security attributes of the socket

   *
   * Description:

   * Set the CIPSO option on the given socket using the DOI definition and
   * security attributes passed to the function.  Returns zero on success and
   * negative values on failure.

   *
   */

  int cipso_v4_req_setattr(struct request_sock *req,
  			 const struct cipso_v4_doi *doi_def,
  			 const struct netlbl_lsm_secattr *secattr)

  {

  	int ret_val = -EPERM;
  	unsigned char *buf = NULL;
  	u32 buf_len;
  	u32 opt_len;

  	struct ip_options_rcu *opt = NULL;

  	struct inet_request_sock *req_inet;

  	/* We allocate the maximum CIPSO option size here so we are probably
  	 * being a little wasteful, but it makes our life _much_ easier later
  	 * on and after all we are only talking about 40 bytes. */
  	buf_len = CIPSO_V4_OPT_LEN_MAX;
  	buf = kmalloc(buf_len, GFP_ATOMIC);
  	if (buf == NULL) {
  		ret_val = -ENOMEM;
  		goto req_setattr_failure;
  	}
  
  	ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
  	if (ret_val < 0)
  		goto req_setattr_failure;
  	buf_len = ret_val;
  
  	/* We can't use ip_options_get() directly because it makes a call to
  	 * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
  	 * we won't always have CAP_NET_RAW even though we _always_ want to
  	 * set the IPOPT_CIPSO option. */
  	opt_len = (buf_len + 3) & ~3;
  	opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
  	if (opt == NULL) {
  		ret_val = -ENOMEM;
  		goto req_setattr_failure;
  	}

  	memcpy(opt->opt.__data, buf, buf_len);
  	opt->opt.optlen = opt_len;
  	opt->opt.cipso = sizeof(struct iphdr);

  	kfree(buf);
  	buf = NULL;
  
  	req_inet = inet_rsk(req);
  	opt = xchg(&req_inet->opt, opt);

  	if (opt)
  		call_rcu(&opt->rcu, opt_kfree_rcu);

  
  	return 0;
  
  req_setattr_failure:
  	kfree(buf);
  	kfree(opt);
  	return ret_val;
  }
  
  /**
   * cipso_v4_delopt - Delete the CIPSO option from a set of IP options
   * @opt_ptr: IP option pointer
   *
   * Description:
   * Deletes the CIPSO IP option from a set of IP options and makes the necessary
   * adjustments to the IP option structure.  Returns zero on success, negative
   * values on failure.
   *
   */

  static int cipso_v4_delopt(struct ip_options_rcu **opt_ptr)

  {
  	int hdr_delta = 0;

  	struct ip_options_rcu *opt = *opt_ptr;

  	if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) {

  		u8 cipso_len;
  		u8 cipso_off;
  		unsigned char *cipso_ptr;
  		int iter;
  		int optlen_new;

  		cipso_off = opt->opt.cipso - sizeof(struct iphdr);
  		cipso_ptr = &opt->opt.__data[cipso_off];

  		cipso_len = cipso_ptr[1];

  		if (opt->opt.srr > opt->opt.cipso)
  			opt->opt.srr -= cipso_len;
  		if (opt->opt.rr > opt->opt.cipso)
  			opt->opt.rr -= cipso_len;
  		if (opt->opt.ts > opt->opt.cipso)
  			opt->opt.ts -= cipso_len;
  		if (opt->opt.router_alert > opt->opt.cipso)
  			opt->opt.router_alert -= cipso_len;
  		opt->opt.cipso = 0;

  
  		memmove(cipso_ptr, cipso_ptr + cipso_len,

  			opt->opt.optlen - cipso_off - cipso_len);

  
  		/* determining the new total option length is tricky because of
  		 * the padding necessary, the only thing i can think to do at
  		 * this point is walk the options one-by-one, skipping the
  		 * padding at the end to determine the actual option size and
  		 * from there we can determine the new total option length */
  		iter = 0;
  		optlen_new = 0;

  		while (iter < opt->opt.optlen)
  			if (opt->opt.__data[iter] != IPOPT_NOP) {
  				iter += opt->opt.__data[iter + 1];

  				optlen_new = iter;
  			} else
  				iter++;

  		hdr_delta = opt->opt.optlen;
  		opt->opt.optlen = (optlen_new + 3) & ~3;
  		hdr_delta -= opt->opt.optlen;

  	} else {
  		/* only the cipso option was present on the socket so we can
  		 * remove the entire option struct */

  		*opt_ptr = NULL;

  		hdr_delta = opt->opt.optlen;
  		call_rcu(&opt->rcu, opt_kfree_rcu);

  	}

  	return hdr_delta;
  }
  
  /**
   * cipso_v4_sock_delattr - Delete the CIPSO option from a socket
   * @sk: the socket
   *
   * Description:
   * Removes the CIPSO option from a socket, if present.
   *
   */
  void cipso_v4_sock_delattr(struct sock *sk)
  {
  	int hdr_delta;

  	struct ip_options_rcu *opt;

  	struct inet_sock *sk_inet;
  
  	sk_inet = inet_sk(sk);

  	opt = rcu_dereference_protected(sk_inet->inet_opt, 1);
  	if (opt == NULL || opt->opt.cipso == 0)

  		return;

  	hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);

  	if (sk_inet->is_icsk && hdr_delta > 0) {
  		struct inet_connection_sock *sk_conn = inet_csk(sk);
  		sk_conn->icsk_ext_hdr_len -= hdr_delta;
  		sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
  	}
  }
  
  /**

   * cipso_v4_req_delattr - Delete the CIPSO option from a request socket
   * @reg: the request socket
   *
   * Description:
   * Removes the CIPSO option from a request socket, if present.
   *
   */
  void cipso_v4_req_delattr(struct request_sock *req)
  {

  	struct ip_options_rcu *opt;

  	struct inet_request_sock *req_inet;
  
  	req_inet = inet_rsk(req);
  	opt = req_inet->opt;

  	if (opt == NULL || opt->opt.cipso == 0)

  		return;
  
  	cipso_v4_delopt(&req_inet->opt);
  }
  
  /**

   * cipso_v4_getattr - Helper function for the cipso_v4_*_getattr functions
   * @cipso: the CIPSO v4 option

   * @secattr: the security attributes
   *
   * Description:

   * Inspect @cipso and return the security attributes in @secattr.  Returns zero
   * on success and negative values on failure.

   *
   */

  static int cipso_v4_getattr(const unsigned char *cipso,
  			    struct netlbl_lsm_secattr *secattr)

  {
  	int ret_val = -ENOMSG;

  	u32 doi;
  	struct cipso_v4_doi *doi_def;

  	if (cipso_v4_cache_check(cipso, cipso[1], secattr) == 0)
  		return 0;

  	doi = get_unaligned_be32(&cipso[2]);

  	rcu_read_lock();

  	doi_def = cipso_v4_doi_search(doi);

  	if (doi_def == NULL)
  		goto getattr_return;

  	/* XXX - This code assumes only one tag per CIPSO option which isn't
  	 * really a good assumption to make but since we only support the MAC
  	 * tags right now it is a safe assumption. */

  	switch (cipso[6]) {

  	case CIPSO_V4_TAG_RBITMAP:

  		ret_val = cipso_v4_parsetag_rbm(doi_def, &cipso[6], secattr);

  		break;

  	case CIPSO_V4_TAG_ENUM:

  		ret_val = cipso_v4_parsetag_enum(doi_def, &cipso[6], secattr);

  		break;

  	case CIPSO_V4_TAG_RANGE:

  		ret_val = cipso_v4_parsetag_rng(doi_def, &cipso[6], secattr);

  		break;

  	case CIPSO_V4_TAG_LOCAL:
  		ret_val = cipso_v4_parsetag_loc(doi_def, &cipso[6], secattr);
  		break;

  	}

  	if (ret_val == 0)
  		secattr->type = NETLBL_NLTYPE_CIPSOV4;

  getattr_return:
  	rcu_read_unlock();

  	return ret_val;
  }
  
  /**

   * cipso_v4_sock_getattr - Get the security attributes from a sock
   * @sk: the sock
   * @secattr: the security attributes
   *
   * Description:
   * Query @sk to see if there is a CIPSO option attached to the sock and if
   * there is return the CIPSO security attributes in @secattr.  This function
   * requires that @sk be locked, or privately held, but it does not do any
   * locking itself.  Returns zero on success and negative values on failure.
   *
   */
  int cipso_v4_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
  {

  	struct ip_options_rcu *opt;
  	int res = -ENOMSG;

  	rcu_read_lock();
  	opt = rcu_dereference(inet_sk(sk)->inet_opt);
  	if (opt && opt->opt.cipso)
  		res = cipso_v4_getattr(opt->opt.__data +
  						opt->opt.cipso -
  						sizeof(struct iphdr),
  				       secattr);
  	rcu_read_unlock();
  	return res;

  }
  
  /**

   * cipso_v4_skbuff_setattr - Set the CIPSO option on a packet
   * @skb: the packet
   * @secattr: the security attributes
   *
   * Description:
   * Set the CIPSO option on the given packet based on the security attributes.
   * Returns a pointer to the IP header on success and NULL on failure.
   *
   */
  int cipso_v4_skbuff_setattr(struct sk_buff *skb,
  			    const struct cipso_v4_doi *doi_def,
  			    const struct netlbl_lsm_secattr *secattr)
  {
  	int ret_val;
  	struct iphdr *iph;
  	struct ip_options *opt = &IPCB(skb)->opt;
  	unsigned char buf[CIPSO_V4_OPT_LEN_MAX];
  	u32 buf_len = CIPSO_V4_OPT_LEN_MAX;
  	u32 opt_len;
  	int len_delta;

  	ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
  	if (ret_val < 0)
  		return ret_val;
  	buf_len = ret_val;

  	opt_len = (buf_len + 3) & ~3;
  
  	/* we overwrite any existing options to ensure that we have enough
  	 * room for the CIPSO option, the reason is that we _need_ to guarantee
  	 * that the security label is applied to the packet - we do the same
  	 * thing when using the socket options and it hasn't caused a problem,
  	 * if we need to we can always revisit this choice later */
  
  	len_delta = opt_len - opt->optlen;
  	/* if we don't ensure enough headroom we could panic on the skb_push()
  	 * call below so make sure we have enough, we are also "mangling" the
  	 * packet so we should probably do a copy-on-write call anyway */
  	ret_val = skb_cow(skb, skb_headroom(skb) + len_delta);
  	if (ret_val < 0)
  		return ret_val;
  
  	if (len_delta > 0) {
  		/* we assume that the header + opt->optlen have already been
  		 * "pushed" in ip_options_build() or similar */
  		iph = ip_hdr(skb);
  		skb_push(skb, len_delta);
  		memmove((char *)iph - len_delta, iph, iph->ihl << 2);
  		skb_reset_network_header(skb);
  		iph = ip_hdr(skb);
  	} else if (len_delta < 0) {
  		iph = ip_hdr(skb);
  		memset(iph + 1, IPOPT_NOP, opt->optlen);
  	} else
  		iph = ip_hdr(skb);
  
  	if (opt->optlen > 0)
  		memset(opt, 0, sizeof(*opt));
  	opt->optlen = opt_len;
  	opt->cipso = sizeof(struct iphdr);
  	opt->is_changed = 1;
  
  	/* we have to do the following because we are being called from a
  	 * netfilter hook which means the packet already has had the header
  	 * fields populated and the checksum calculated - yes this means we
  	 * are doing more work than needed but we do it to keep the core
  	 * stack clean and tidy */
  	memcpy(iph + 1, buf, buf_len);
  	if (opt_len > buf_len)
  		memset((char *)(iph + 1) + buf_len, 0, opt_len - buf_len);
  	if (len_delta != 0) {
  		iph->ihl = 5 + (opt_len >> 2);
  		iph->tot_len = htons(skb->len);
  	}
  	ip_send_check(iph);
  
  	return 0;
  }
  
  /**
   * cipso_v4_skbuff_delattr - Delete any CIPSO options from a packet
   * @skb: the packet
   *
   * Description:
   * Removes any and all CIPSO options from the given packet.  Returns zero on
   * success, negative values on failure.
   *
   */
  int cipso_v4_skbuff_delattr(struct sk_buff *skb)
  {
  	int ret_val;
  	struct iphdr *iph;
  	struct ip_options *opt = &IPCB(skb)->opt;
  	unsigned char *cipso_ptr;
  
  	if (opt->cipso == 0)
  		return 0;
  
  	/* since we are changing the packet we should make a copy */
  	ret_val = skb_cow(skb, skb_headroom(skb));
  	if (ret_val < 0)
  		return ret_val;
  
  	/* the easiest thing to do is just replace the cipso option with noop
  	 * options since we don't change the size of the packet, although we
  	 * still need to recalculate the checksum */
  
  	iph = ip_hdr(skb);
  	cipso_ptr = (unsigned char *)iph + opt->cipso;
  	memset(cipso_ptr, IPOPT_NOOP, cipso_ptr[1]);
  	opt->cipso = 0;
  	opt->is_changed = 1;
  
  	ip_send_check(iph);
  
  	return 0;
  }
  
  /**

   * cipso_v4_skbuff_getattr - Get the security attributes from the CIPSO option
   * @skb: the packet
   * @secattr: the security attributes
   *
   * Description:
   * Parse the given packet's CIPSO option and return the security attributes.
   * Returns zero on success and negative values on failure.
   *
   */
  int cipso_v4_skbuff_getattr(const struct sk_buff *skb,
  			    struct netlbl_lsm_secattr *secattr)
  {

  	return cipso_v4_getattr(CIPSO_V4_OPTPTR(skb), secattr);

  }
  
  /*
   * Setup Functions
   */
  
  /**
   * cipso_v4_init - Initialize the CIPSO module
   *
   * Description:
   * Initialize the CIPSO module and prepare it for use.  Returns zero on success
   * and negative values on failure.
   *
   */
  static int __init cipso_v4_init(void)
  {
  	int ret_val;
  
  	ret_val = cipso_v4_cache_init();
  	if (ret_val != 0)
  		panic("Failed to initialize the CIPSO/IPv4 cache (%d)
  ",
  		      ret_val);
  
  	return 0;
  }
  
  subsys_initcall(cipso_v4_init);