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cipso_ipv4.c

/*
 * 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);

      spin_lock(&cipso_v4_doi_list_lock);
      if (cipso_v4_doi_search(doi_def->doi) != NULL)
            goto doi_add_failure;
      list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
      spin_unlock(&cipso_v4_doi_list_lock);

      return 0;

doi_add_failure:
      spin_unlock(&cipso_v4_doi_list_lock);
      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;

      spin_lock(&cipso_v4_doi_list_lock);
      doi_def = cipso_v4_doi_search(doi);
      if (doi_def != NULL) {
            doi_def->valid = 0;
            list_del_rcu(&doi_def->list);
            spin_unlock(&cipso_v4_doi_list_lock);
            rcu_read_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);
            rcu_read_unlock();
            cipso_v4_cache_invalidate();
            call_rcu(&doi_def->rcu, callback);
            return 0;
      }
      spin_unlock(&cipso_v4_doi_list_lock);

      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);

      spin_lock(&cipso_v4_doi_list_lock);
      list_for_each_entry(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);
                  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);

      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;

      spin_lock(&cipso_v4_doi_list_lock);
      list_for_each_entry(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);
                  call_rcu(&iter->rcu, cipso_v4_doi_domhsh_free);
                  return 0;
            }
      spin_unlock(&cipso_v4_doi_list_lock);

      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_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 = ntohl(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;
      }

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 *opt;

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

      return cipso_v4_getattr(opt->__data + opt->cipso - sizeof(struct iphdr),
                        secattr);
}

/**
 * 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)\n",
                  ret_val);

      return 0;
}

subsys_initcall(cipso_v4_init);

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