/*
   * 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, copies of both documents can be found in the Documentation
   * directory.  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.
   *
   * 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 <linux/rcupdate.h>
  #include <linux/list.h>
  #include <linux/spinlock.h>
  #include <linux/string.h>
  #include <linux/jhash.h>
  #include <net/ip.h>
  #include <net/icmp.h>
  #include <net/tcp.h>
  #include <net/netlabel.h>
  #include <net/cipso_ipv4.h>

  #include <asm/atomic.h>

  #include <asm/bug.h>

  #include <asm/unaligned.h>

  
  struct cipso_v4_domhsh_entry {
  	char *domain;
  	u32 valid;
  	struct list_head list;
  	struct rcu_head rcu;
  };
  
  /* List of available DOI definitions */
  /* XXX - Updates should be minimal so having a single lock for the
   * cipso_v4_doi_list and the cipso_v4_doi_list->dom_list should be
   * okay. */
  /* 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 struct list_head cipso_v4_doi_list = LIST_HEAD_INIT(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 possibile to fit 8 category ranges because the zero should
   * be omitted. */
  #define CIPSO_V4_TAG_RNG_CAT_MAX      8
  
  /*

   * 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_doi_domhsh_free - Frees a domain list entry
   * @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 a domain list entry can be released
   * safely.
   *
   */
  static void cipso_v4_doi_domhsh_free(struct rcu_head *entry)
  {
  	struct cipso_v4_domhsh_entry *ptr;
  
  	ptr = container_of(entry, struct cipso_v4_domhsh_entry, rcu);
  	kfree(ptr->domain);
  	kfree(ptr);
  }
  
  /**
   * 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);

  	}
  
  	return;
  }
  
  /**
   * 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_BUCKETBITS - 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;

  			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_BUCKETBITS - 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 responsibile 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 && iter->valid)
  			return iter;
  	return NULL;
  }
  
  /**
   * cipso_v4_doi_add - Add a new DOI to the CIPSO protocol engine
   * @doi_def: the DOI structure
   *
   * 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)
  {

  	u32 iter;

  	if (doi_def == NULL || doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
  		return -EINVAL;

  	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:
  			if (doi_def->type != CIPSO_V4_MAP_PASS)
  				return -EINVAL;
  			break;

  		case CIPSO_V4_TAG_INVALID:
  			if (iter == 0)
  				return -EINVAL;
  			break;

  		case CIPSO_V4_TAG_ENUM:
  			if (doi_def->type != CIPSO_V4_MAP_PASS)
  				return -EINVAL;
  			break;

  		default:
  			return -EINVAL;
  		}
  	}

  
  	doi_def->valid = 1;
  	INIT_RCU_HEAD(&doi_def->rcu);
  	INIT_LIST_HEAD(&doi_def->dom_list);
  
  	rcu_read_lock();
  	if (cipso_v4_doi_search(doi_def->doi) != NULL)
  		goto doi_add_failure_rlock;
  	spin_lock(&cipso_v4_doi_list_lock);
  	if (cipso_v4_doi_search(doi_def->doi) != NULL)
  		goto doi_add_failure_slock;
  	list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
  	spin_unlock(&cipso_v4_doi_list_lock);
  	rcu_read_unlock();
  
  	return 0;
  
  doi_add_failure_slock:
  	spin_unlock(&cipso_v4_doi_list_lock);
  doi_add_failure_rlock:
  	rcu_read_unlock();
  	return -EEXIST;
  }
  
  /**
   * 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

   * @callback: the DOI cleanup/free callback
   *
   * Description:
   * Removes a DOI definition from the CIPSO engine, @callback is called to
   * free any memory.  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,

  			void (*callback) (struct rcu_head * head))

  {
  	struct cipso_v4_doi *doi_def;
  	struct cipso_v4_domhsh_entry *dom_iter;
  
  	rcu_read_lock();
  	if (cipso_v4_doi_search(doi) != NULL) {
  		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);
  			rcu_read_unlock();
  			return -ENOENT;
  		}
  		doi_def->valid = 0;
  		list_del_rcu(&doi_def->list);
  		spin_unlock(&cipso_v4_doi_list_lock);
  		list_for_each_entry_rcu(dom_iter, &doi_def->dom_list, list)
  			if (dom_iter->valid)

  				netlbl_domhsh_remove(dom_iter->domain,

  						     audit_info);

  		cipso_v4_cache_invalidate();
  		rcu_read_unlock();
  
  		call_rcu(&doi_def->rcu, callback);
  		return 0;
  	}
  	rcu_read_unlock();
  
  	return -ENOENT;
  }
  
  /**
   * cipso_v4_doi_getdef - Returns a pointer 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.
   *
   */
  struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi)
  {
  	return cipso_v4_doi_search(doi);
  }
  
  /**

   * 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 (iter_doi->valid) {
  			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;

  }
  
  /**
   * cipso_v4_doi_domhsh_add - Adds a domain entry to a DOI definition
   * @doi_def: the DOI definition
   * @domain: the domain to add
   *
   * Description:

   * Adds the @domain to the DOI specified by @doi_def, this function

   * should only be called by external functions (i.e. NetLabel).  This function
   * does allocate memory.  Returns zero on success, negative values on failure.
   *
   */
  int cipso_v4_doi_domhsh_add(struct cipso_v4_doi *doi_def, const char *domain)
  {
  	struct cipso_v4_domhsh_entry *iter;
  	struct cipso_v4_domhsh_entry *new_dom;
  
  	new_dom = kzalloc(sizeof(*new_dom), GFP_KERNEL);
  	if (new_dom == NULL)
  		return -ENOMEM;
  	if (domain) {
  		new_dom->domain = kstrdup(domain, GFP_KERNEL);
  		if (new_dom->domain == NULL) {
  			kfree(new_dom);
  			return -ENOMEM;
  		}
  	}
  	new_dom->valid = 1;
  	INIT_RCU_HEAD(&new_dom->rcu);
  
  	rcu_read_lock();
  	spin_lock(&cipso_v4_doi_list_lock);
  	list_for_each_entry_rcu(iter, &doi_def->dom_list, list)
  		if (iter->valid &&
  		    ((domain != NULL && iter->domain != NULL &&
  		      strcmp(iter->domain, domain) == 0) ||
  		     (domain == NULL && iter->domain == NULL))) {
  			spin_unlock(&cipso_v4_doi_list_lock);
  			rcu_read_unlock();
  			kfree(new_dom->domain);
  			kfree(new_dom);
  			return -EEXIST;
  		}
  	list_add_tail_rcu(&new_dom->list, &doi_def->dom_list);
  	spin_unlock(&cipso_v4_doi_list_lock);
  	rcu_read_unlock();
  
  	return 0;
  }
  
  /**
   * cipso_v4_doi_domhsh_remove - Removes a domain entry from a DOI definition
   * @doi_def: the DOI definition
   * @domain: the domain to remove
   *
   * Description:
   * Removes the @domain from the DOI specified by @doi_def, this function
   * should only be called by external functions (i.e. NetLabel).   Returns zero
   * on success and negative values on error.
   *
   */
  int cipso_v4_doi_domhsh_remove(struct cipso_v4_doi *doi_def,
  			       const char *domain)
  {
  	struct cipso_v4_domhsh_entry *iter;
  
  	rcu_read_lock();
  	spin_lock(&cipso_v4_doi_list_lock);
  	list_for_each_entry_rcu(iter, &doi_def->dom_list, list)
  		if (iter->valid &&
  		    ((domain != NULL && iter->domain != NULL &&
  		      strcmp(iter->domain, domain) == 0) ||
  		     (domain == NULL && iter->domain == NULL))) {
  			iter->valid = 0;
  			list_del_rcu(&iter->list);
  			spin_unlock(&cipso_v4_doi_list_lock);
  			rcu_read_unlock();
  			call_rcu(&iter->rcu, cipso_v4_doi_domhsh_free);
  
  			return 0;
  		}
  	spin_unlock(&cipso_v4_doi_list_lock);
  	rcu_read_unlock();
  
  	return -ENOENT;
  }
  
  /*
   * 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_STD:
  		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_STD:

  		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_STD:
  		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_STD:

  		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_STD) {

  		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->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_STD:

  			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_STD) {

  		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_STD:
  			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->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 = ntohs(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->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->mls_cat,

  				ntohs(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 = ntohs(get_unaligned((__be16 *)&rngcat[iter]));

  		if ((iter + 4) <= rngcat_len)

  			cat_low = ntohs(
  				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->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->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 = ntohs(get_unaligned((__be16 *)&net_cat[net_iter]));

  		if ((net_iter + 4) <= net_cat_len)

  			cat_low = ntohs(
  			      get_unaligned((__be16 *)&net_cat[net_iter + 2]));

  		else
  			cat_low = 0;
  
  		ret_val = netlbl_secattr_catmap_setrng(secattr->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->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
  		 * possibile 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] = 0x01;
  	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->mls_lvl = level;

  	secattr->flags |= NETLBL_SECATTR_MLS_LVL;

  
  	if (tag_len > 4) {

  		secattr->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);

  		if (secattr->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->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->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] = 0x02;
  	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->mls_lvl = level;
  	secattr->flags |= NETLBL_SECATTR_MLS_LVL;
  
  	if (tag_len > 4) {
  		secattr->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
  		if (secattr->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->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->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] = 0x05;
  	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->mls_lvl = level;
  	secattr->flags |= NETLBL_SECATTR_MLS_LVL;
  
  	if (tag_len > 4) {
  		secattr->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
  		if (secattr->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->mls_cat);
  			return ret_val;
  		}
  
  		secattr->flags |= NETLBL_SECATTR_MLS_CAT;
  	}
  
  	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(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(ntohl(get_unaligned((__be32 *)&opt[2])));

  	if (doi_def == NULL) {
  		err_offset = 2;
  		goto validate_return_locked;
  	}
  
  	opt_iter = 6;
  	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 < 4) {
  				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 > 4 &&
  				    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 < 4) {
  				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 > 4 &&
  			    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 < 4) {
  				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 > 4 &&
  			    cipso_v4_map_cat_rng_valid(doi_def,
  						       &tag[4],
  						       tag_len - 4) < 0) {
  				err_offset = opt_iter + 4;
  				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 reponse 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_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;
  	u32 iter;

  	unsigned char *buf;

  	u32 buf_len = 0;
  	u32 opt_len;
  	struct ip_options *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;
  	}

  	/* 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;

  		default:
  			ret_val = -EPERM;
  			goto socket_setattr_failure;
  		}
  
  		iter++;

  	} while (ret_val < 0 &&

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

  	if (ret_val < 0)

  		goto socket_setattr_failure;

  	cipso_v4_gentag_hdr(doi_def, buf, ret_val);
  	buf_len = CIPSO_V4_HDR_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->__data, buf, buf_len);
  	opt->optlen = opt_len;
  	opt->is_data = 1;

  	opt->cipso = sizeof(struct iphdr);

  	kfree(buf);
  	buf = NULL;

  
  	sk_inet = inet_sk(sk);
  	if (sk_inet->is_icsk) {
  		sk_conn = inet_csk(sk);
  		if (sk_inet->opt)
  			sk_conn->icsk_ext_hdr_len -= sk_inet->opt->optlen;
  		sk_conn->icsk_ext_hdr_len += opt->optlen;
  		sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
  	}
  	opt = xchg(&sk_inet->opt, opt);
  	kfree(opt);
  
  	return 0;
  
  socket_setattr_failure:
  	kfree(buf);
  	kfree(opt);
  	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)

  {
  	int ret_val = -ENOMSG;

  	struct inet_sock *sk_inet;
  	unsigned char *cipso_ptr;
  	u32 doi;
  	struct cipso_v4_doi *doi_def;

  	sk_inet = inet_sk(sk);
  	if (sk_inet->opt == NULL || sk_inet->opt->cipso == 0)

  		return -ENOMSG;

  	cipso_ptr = sk_inet->opt->__data + sk_inet->opt->cipso -
  		sizeof(struct iphdr);
  	ret_val = cipso_v4_cache_check(cipso_ptr, cipso_ptr[1], secattr);
  	if (ret_val == 0)

  		return ret_val;

  	doi = ntohl(get_unaligned((__be32 *)&cipso_ptr[2]));

  	rcu_read_lock();

  	doi_def = cipso_v4_doi_search(doi);

  	if (doi_def == NULL) {
  		rcu_read_unlock();

  		return -ENOMSG;

  	}

  
  	/* 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_ptr[6]) {
  	case CIPSO_V4_TAG_RBITMAP:
  		ret_val = cipso_v4_parsetag_rbm(doi_def,
  						&cipso_ptr[6],
  						secattr);
  		break;

  	case CIPSO_V4_TAG_ENUM:
  		ret_val = cipso_v4_parsetag_enum(doi_def,
  						 &cipso_ptr[6],
  						 secattr);
  		break;

  	case CIPSO_V4_TAG_RANGE:
  		ret_val = cipso_v4_parsetag_rng(doi_def,
  						&cipso_ptr[6],
  						secattr);
  		break;

  	}
  	rcu_read_unlock();

  	return ret_val;
  }
  
  /**

   * 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)
  {
  	int ret_val = -ENOMSG;
  	unsigned char *cipso_ptr;
  	u32 doi;
  	struct cipso_v4_doi *doi_def;

  	cipso_ptr = CIPSO_V4_OPTPTR(skb);
  	if (cipso_v4_cache_check(cipso_ptr, cipso_ptr[1], secattr) == 0)
  		return 0;

  	doi = ntohl(get_unaligned((__be32 *)&cipso_ptr[2]));

  	rcu_read_lock();

  	doi_def = cipso_v4_doi_search(doi);

  	if (doi_def == NULL)
  		goto skbuff_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_ptr[6]) {
  	case CIPSO_V4_TAG_RBITMAP:
  		ret_val = cipso_v4_parsetag_rbm(doi_def,
  						&cipso_ptr[6],
  						secattr);
  		break;

  	case CIPSO_V4_TAG_ENUM:
  		ret_val = cipso_v4_parsetag_enum(doi_def,
  						 &cipso_ptr[6],
  						 secattr);
  		break;

  	case CIPSO_V4_TAG_RANGE:
  		ret_val = cipso_v4_parsetag_rng(doi_def,
  						&cipso_ptr[6],
  						secattr);
  		break;

  	}
  
  skbuff_getattr_return:
  	rcu_read_unlock();
  	return ret_val;
  }
  
  /*
   * 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);