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 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * CIPSO - Commercial IP Security Option
  *
  * This is an implementation of the CIPSO 2.2 protocol as specified in
  * draft-ietf-cipso-ipsecurity-01.txt with additional tag types as found in
  * FIPS-188.  While CIPSO never became a full IETF RFC standard many vendors
  * have chosen to adopt the protocol and over the years it has become a
  * de-facto standard for labeled networking.
  *
  * The CIPSO draft specification can be found in the kernel's Documentation
  * directory as well as the following URL:
  *   https://tools.ietf.org/id/draft-ietf-cipso-ipsecurity-01.txt
  * The FIPS-188 specification can be found at the following URL:
  *   https://www.itl.nist.gov/fipspubs/fip188.htm
  *
  * Author: Paul Moore <paul.moore@hp.com>
  */
 
 /*
  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008
  */
 
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/rcupdate.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/jhash.h>
 #include <linux/audit.h>
 #include <linux/slab.h>
 #include <net/ip.h>
 #include <net/icmp.h>
 #include <net/tcp.h>
 #include <net/netlabel.h>
 #include <net/cipso_ipv4.h>
 #include <linux/atomic.h>
 #include <linux/bug.h>
 #include <asm/unaligned.h>
 
 /* List of available DOI definitions */
 /* XXX - This currently assumes a minimal number of different DOIs in use,
  * if in practice there are a lot of different DOIs this list should
  * probably be turned into a hash table or something similar so we
  * can do quick lookups. */
 static DEFINE_SPINLOCK(cipso_v4_doi_list_lock);
 static LIST_HEAD(cipso_v4_doi_list);
 
 /* Label mapping cache */
 int cipso_v4_cache_enabled = 1;
 int cipso_v4_cache_bucketsize = 10;
 #define CIPSO_V4_CACHE_BUCKETBITS     7
 #define CIPSO_V4_CACHE_BUCKETS        (1 << CIPSO_V4_CACHE_BUCKETBITS)
 #define CIPSO_V4_CACHE_REORDERLIMIT   10
 struct cipso_v4_map_cache_bkt {
     spinlock_t lock;
     u32 size;
     struct list_head list;
 };
 
 struct cipso_v4_map_cache_entry {
     u32 hash;
     unsigned char *key;
     size_t key_len;
 
     struct netlbl_lsm_cache *lsm_data;
 
     u32 activity;
     struct list_head list;
 };
 
 static struct cipso_v4_map_cache_bkt *cipso_v4_cache;
 
 /* Restricted bitmap (tag #1) flags */
 int cipso_v4_rbm_optfmt;
 int cipso_v4_rbm_strictvalid = 1;
 
 /*
  * Protocol Constants
  */
 
 /* Maximum size of the CIPSO IP option, derived from the fact that the maximum
  * IPv4 header size is 60 bytes and the base IPv4 header is 20 bytes long. */
 #define CIPSO_V4_OPT_LEN_MAX          40
 
 /* Length of the base CIPSO option, this includes the option type (1 byte), the
  * option length (1 byte), and the DOI (4 bytes). */
 #define CIPSO_V4_HDR_LEN              6
 
 /* Base length of the restrictive category bitmap tag (tag #1). */
 #define CIPSO_V4_TAG_RBM_BLEN         4
 
 /* Base length of the enumerated category tag (tag #2). */
 #define CIPSO_V4_TAG_ENUM_BLEN        4
 
 /* Base length of the ranged categories bitmap tag (tag #5). */
 #define CIPSO_V4_TAG_RNG_BLEN         4
 /* The maximum number of category ranges permitted in the ranged category tag
  * (tag #5).  You may note that the IETF draft states that the maximum number
  * of category ranges is 7, but if the low end of the last category range is
  * zero then it is possible to fit 8 category ranges because the zero should
  * be omitted. */
 #define CIPSO_V4_TAG_RNG_CAT_MAX      8
 
 /* Base length of the local tag (non-standard tag).
  *  Tag definition (may change between kernel versions)
  *
  * 0          8          16         24         32
  * +----------+----------+----------+----------+
  * | 10000000 | 00000110 | 32-bit secid value  |
  * +----------+----------+----------+----------+
  * | in (host byte order)|
  * +----------+----------+
  *
  */
 #define CIPSO_V4_TAG_LOC_BLEN         6
 
 /*
  * Helper Functions
  */
 
 /**
  * cipso_v4_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 __init 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)
         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.
  *
  */
 void cipso_v4_cache_invalidate(void)
 {
     struct cipso_v4_map_cache_entry *entry, *tmp_entry;
     u32 iter;
 
     for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {
         spin_lock_bh(&cipso_v4_cache[iter].lock);
         list_for_each_entry_safe(entry,
                      tmp_entry,
                      &cipso_v4_cache[iter].list, list) {
             list_del(&entry->list);
             cipso_v4_cache_entry_free(entry);
         }
         cipso_v4_cache[iter].size = 0;
         spin_unlock_bh(&cipso_v4_cache[iter].lock);
     }
 }
 
 /**
  * cipso_v4_cache_check - Check the CIPSO cache for a label mapping
  * @key: the buffer to check
  * @key_len: buffer length in bytes
  * @secattr: the security attribute struct to use
  *
  * Description:
  * This function checks the cache to see if a label mapping already exists for
  * the given key.  If there is a match then the cache is adjusted and the
  * @secattr struct is populated with the correct LSM security attributes.  The
  * cache is adjusted in the following manner if the entry is not already the
  * first in the cache bucket:
  *
  *  1. The cache entry's activity counter is incremented
  *  2. The previous (higher ranking) entry's activity counter is decremented
  *  3. If the difference between the two activity counters is geater than
  *     CIPSO_V4_CACHE_REORDERLIMIT the two entries are swapped
  *
  * Returns zero on success, -ENOENT for a cache miss, and other negative values
  * on error.
  *
  */
 static int cipso_v4_cache_check(const unsigned char *key,
                 u32 key_len,
                 struct netlbl_lsm_secattr *secattr)
 {
     u32 bkt;
     struct cipso_v4_map_cache_entry *entry;
     struct cipso_v4_map_cache_entry *prev_entry = NULL;
     u32 hash;
 
     if (!READ_ONCE(cipso_v4_cache_enabled))
         return -ENOENT;
 
     hash = cipso_v4_map_cache_hash(key, key_len);
     bkt = hash & (CIPSO_V4_CACHE_BUCKETS - 1);
     spin_lock_bh(&cipso_v4_cache[bkt].lock);
     list_for_each_entry(entry, &cipso_v4_cache[bkt].list, list) {
         if (entry->hash == hash &&
             entry->key_len == key_len &&
             memcmp(entry->key, key, key_len) == 0) {
             entry->activity += 1;
             refcount_inc(&entry->lsm_data->refcount);
             secattr->cache = entry->lsm_data;
             secattr->flags |= NETLBL_SECATTR_CACHE;
             secattr->type = NETLBL_NLTYPE_CIPSOV4;
             if (!prev_entry) {
                 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
  * @cipso_ptr: pointer to CIPSO IP option
  * @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 unsigned char *cipso_ptr,
                const struct netlbl_lsm_secattr *secattr)
 {
     int bkt_size = READ_ONCE(cipso_v4_cache_bucketsize);
     int ret_val = -EPERM;
     u32 bkt;
     struct cipso_v4_map_cache_entry *entry = NULL;
     struct cipso_v4_map_cache_entry *old_entry = NULL;
     u32 cipso_ptr_len;
 
     if (!READ_ONCE(cipso_v4_cache_enabled) || bkt_size <= 0)
         return 0;
 
     cipso_ptr_len = cipso_ptr[1];
 
     entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
     if (!entry)
         return -ENOMEM;
     entry->key = kmemdup(cipso_ptr, cipso_ptr_len, GFP_ATOMIC);
     if (!entry->key) {
         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);
     refcount_inc(&secattr->cache->refcount);
     entry->lsm_data = secattr->cache;
 
     bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
     spin_lock_bh(&cipso_v4_cache[bkt].lock);
     if (cipso_v4_cache[bkt].size < bkt_size) {
         list_add(&entry->list, &cipso_v4_cache[bkt].list);
         cipso_v4_cache[bkt].size += 1;
     } else {
         old_entry = list_entry(cipso_v4_cache[bkt].list.prev,
                        struct cipso_v4_map_cache_entry, list);
         list_del(&old_entry->list);
         list_add(&entry->list, &cipso_v4_cache[bkt].list);
         cipso_v4_cache_entry_free(old_entry);
     }
     spin_unlock_bh(&cipso_v4_cache[bkt].lock);
 
     return 0;
 
 cache_add_failure:
     if (entry)
         cipso_v4_cache_entry_free(entry);
     return ret_val;
 }
 
 /*
  * DOI List Functions
  */
 
 /**
  * cipso_v4_doi_search - Searches for a DOI definition
  * @doi: the DOI to search for
  *
  * Description:
  * Search the DOI definition list for a DOI definition with a DOI value that
  * matches @doi.  The caller is responsible for calling rcu_read_[un]lock().
  * Returns a pointer to the DOI definition on success and NULL on failure.
  */
 static struct cipso_v4_doi *cipso_v4_doi_search(u32 doi)
 {
     struct cipso_v4_doi *iter;
 
     list_for_each_entry_rcu(iter, &cipso_v4_doi_list, list)
         if (iter->doi == doi && refcount_read(&iter->refcount))
             return iter;
     return NULL;
 }
 
 /**
  * cipso_v4_doi_add - Add a new DOI to the CIPSO protocol engine
  * @doi_def: the DOI structure
  * @audit_info: NetLabel audit information
  *
  * Description:
  * The caller defines a new DOI for use by the CIPSO engine and calls this
  * function to add it to the list of acceptable domains.  The caller must
  * ensure that the mapping table specified in @doi_def->map meets all of the
  * requirements of the mapping type (see cipso_ipv4.h for details).  Returns
  * zero on success and non-zero on failure.
  *
  */
 int cipso_v4_doi_add(struct cipso_v4_doi *doi_def,
              struct netlbl_audit *audit_info)
 {
     int ret_val = -EINVAL;
     u32 iter;
     u32 doi;
     u32 doi_type;
     struct audit_buffer *audit_buf;
 
     doi = doi_def->doi;
     doi_type = doi_def->type;
 
     if (doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
         goto doi_add_return;
     for (iter = 0; iter < CIPSO_V4_TAG_MAXCNT; iter++) {
         switch (doi_def->tags[iter]) {
         case CIPSO_V4_TAG_RBITMAP:
             break;
         case CIPSO_V4_TAG_RANGE:
         case CIPSO_V4_TAG_ENUM:
             if (doi_def->type != CIPSO_V4_MAP_PASS)
                 goto doi_add_return;
             break;
         case CIPSO_V4_TAG_LOCAL:
             if (doi_def->type != CIPSO_V4_MAP_LOCAL)
                 goto doi_add_return;
             break;
         case CIPSO_V4_TAG_INVALID:
             if (iter == 0)
                 goto doi_add_return;
             break;
         default:
             goto doi_add_return;
         }
     }
 
     refcount_set(&doi_def->refcount, 1);
 
     spin_lock(&cipso_v4_doi_list_lock);
     if (cipso_v4_doi_search(doi_def->doi)) {
         spin_unlock(&cipso_v4_doi_list_lock);
         ret_val = -EEXIST;
         goto doi_add_return;
     }
     list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
     spin_unlock(&cipso_v4_doi_list_lock);
     ret_val = 0;
 
 doi_add_return:
     audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_ADD, audit_info);
     if (audit_buf) {
         const char *type_str;
         switch (doi_type) {
         case CIPSO_V4_MAP_TRANS:
             type_str = "trans";
             break;
         case CIPSO_V4_MAP_PASS:
             type_str = "pass";
             break;
         case CIPSO_V4_MAP_LOCAL:
             type_str = "local";
             break;
         default:
             type_str = "(unknown)";
         }
         audit_log_format(audit_buf,
                  " cipso_doi=%u cipso_type=%s res=%u",
                  doi, type_str, ret_val == 0 ? 1 : 0);
         audit_log_end(audit_buf);
     }
 
     return ret_val;
 }
 
 /**
  * cipso_v4_doi_free - Frees a DOI definition
  * @doi_def: the DOI definition
  *
  * Description:
  * This function frees all of the memory associated with a DOI definition.
  *
  */
 void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
 {
     if (!doi_def)
         return;
 
     switch (doi_def->type) {
     case CIPSO_V4_MAP_TRANS:
         kfree(doi_def->map.std->lvl.cipso);
         kfree(doi_def->map.std->lvl.local);
         kfree(doi_def->map.std->cat.cipso);
         kfree(doi_def->map.std->cat.local);
         kfree(doi_def->map.std);
         break;
     }
     kfree(doi_def);
 }
 
 /**
  * cipso_v4_doi_free_rcu - Frees a DOI definition via the RCU pointer
  * @entry: the entry's RCU field
  *
  * Description:
  * This function is designed to be used as a callback to the call_rcu()
  * function so that the memory allocated to the DOI definition can be released
  * safely.
  *
  */
 static void cipso_v4_doi_free_rcu(struct rcu_head *entry)
 {
     struct cipso_v4_doi *doi_def;
 
     doi_def = container_of(entry, struct cipso_v4_doi, rcu);
     cipso_v4_doi_free(doi_def);
 }
 
 /**
  * cipso_v4_doi_remove - Remove an existing DOI from the CIPSO protocol engine
  * @doi: the DOI value
  * @audit_info: NetLabel audit information
  *
  * Description:
  * Removes a DOI definition from the CIPSO engine.  The NetLabel routines will
  * be called to release their own LSM domain mappings as well as our own
  * domain list.  Returns zero on success and negative values on failure.
  *
  */
 int cipso_v4_doi_remove(u32 doi, struct netlbl_audit *audit_info)
 {
     int ret_val;
     struct cipso_v4_doi *doi_def;
     struct audit_buffer *audit_buf;
 
     spin_lock(&cipso_v4_doi_list_lock);
     doi_def = cipso_v4_doi_search(doi);
     if (!doi_def) {
         spin_unlock(&cipso_v4_doi_list_lock);
         ret_val = -ENOENT;
         goto doi_remove_return;
     }
     list_del_rcu(&doi_def->list);
     spin_unlock(&cipso_v4_doi_list_lock);
 
     cipso_v4_doi_putdef(doi_def);
     ret_val = 0;
 
 doi_remove_return:
     audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_DEL, audit_info);
     if (audit_buf) {
         audit_log_format(audit_buf,
                  " cipso_doi=%u res=%u",
                  doi, ret_val == 0 ? 1 : 0);
         audit_log_end(audit_buf);
     }
 
     return ret_val;
 }
 
 /**
  * cipso_v4_doi_getdef - Returns a reference to a valid DOI definition
  * @doi: the DOI value
  *
  * Description:
  * Searches for a valid DOI definition and if one is found it is returned to
  * the caller.  Otherwise NULL is returned.  The caller must ensure that
  * rcu_read_lock() is held while accessing the returned definition and the DOI
  * definition reference count is decremented when the caller is done.
  *
  */
 struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi)
 {
     struct cipso_v4_doi *doi_def;
 
     rcu_read_lock();
     doi_def = cipso_v4_doi_search(doi);
     if (!doi_def)
         goto doi_getdef_return;
     if (!refcount_inc_not_zero(&doi_def->refcount))
         doi_def = NULL;
 
 doi_getdef_return:
     rcu_read_unlock();
     return doi_def;
 }
 
 /**
  * cipso_v4_doi_putdef - Releases a reference for the given DOI definition
  * @doi_def: the DOI definition
  *
  * Description:
  * Releases a DOI definition reference obtained from cipso_v4_doi_getdef().
  *
  */
 void cipso_v4_doi_putdef(struct cipso_v4_doi *doi_def)
 {
     if (!doi_def)
         return;
 
     if (!refcount_dec_and_test(&doi_def->refcount))
         return;
 
     cipso_v4_cache_invalidate();
     call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);
 }
 
 /**
  * cipso_v4_doi_walk - Iterate through the DOI definitions
  * @skip_cnt: skip past this number of DOI definitions, updated
  * @callback: callback for each DOI definition
  * @cb_arg: argument for the callback function
  *
  * Description:
  * Iterate over the DOI definition list, skipping the first @skip_cnt entries.
  * For each entry call @callback, if @callback returns a negative value stop
  * 'walking' through the list and return.  Updates the value in @skip_cnt upon
  * return.  Returns zero on success, negative values on failure.
  *
  */
 int cipso_v4_doi_walk(u32 *skip_cnt,
              int (*callback) (struct cipso_v4_doi *doi_def, void *arg),
              void *cb_arg)
 {
     int ret_val = -ENOENT;
     u32 doi_cnt = 0;
     struct cipso_v4_doi *iter_doi;
 
     rcu_read_lock();
     list_for_each_entry_rcu(iter_doi, &cipso_v4_doi_list, list)
         if (refcount_read(&iter_doi->refcount) > 0) {
             if (doi_cnt++ < *skip_cnt)
                 continue;
             ret_val = callback(iter_doi, cb_arg);
             if (ret_val < 0) {
                 doi_cnt--;
                 goto doi_walk_return;
             }
         }
 
 doi_walk_return:
     rcu_read_unlock();
     *skip_cnt = doi_cnt;
     return ret_val;
 }
 
 /*
  * Label Mapping Functions
  */
 
 /**
  * cipso_v4_map_lvl_valid - Checks to see if the given level is understood
  * @doi_def: the DOI definition
  * @level: the level to check
  *
  * Description:
  * Checks the given level against the given DOI definition and returns a
  * negative value if the level does not have a valid mapping and a zero value
  * if the level is defined by the DOI.
  *
  */
 static int cipso_v4_map_lvl_valid(const struct cipso_v4_doi *doi_def, u8 level)
 {
     switch (doi_def->type) {
     case CIPSO_V4_MAP_PASS:
         return 0;
     case CIPSO_V4_MAP_TRANS:
         if ((level < doi_def->map.std->lvl.cipso_size) &&
             (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL))
             return 0;
         break;
     }
 
     return -EFAULT;
 }
 
 /**
  * cipso_v4_map_lvl_hton - Perform a level mapping from the host to the network
  * @doi_def: the DOI definition
  * @host_lvl: the host MLS level
  * @net_lvl: the network/CIPSO MLS level
  *
  * Description:
  * Perform a label mapping to translate a local MLS level to the correct
  * CIPSO level using the given DOI definition.  Returns zero on success,
  * negative values otherwise.
  *
  */
 static int cipso_v4_map_lvl_hton(const struct cipso_v4_doi *doi_def,
                  u32 host_lvl,
                  u32 *net_lvl)
 {
     switch (doi_def->type) {
     case CIPSO_V4_MAP_PASS:
         *net_lvl = host_lvl;
         return 0;
     case CIPSO_V4_MAP_TRANS:
         if (host_lvl < doi_def->map.std->lvl.local_size &&
             doi_def->map.std->lvl.local[host_lvl] < CIPSO_V4_INV_LVL) {
             *net_lvl = doi_def->map.std->lvl.local[host_lvl];
             return 0;
         }
         return -EPERM;
     }
 
     return -EINVAL;
 }
 
 /**
  * cipso_v4_map_lvl_ntoh - Perform a level mapping from the network to the host
  * @doi_def: the DOI definition
  * @net_lvl: the network/CIPSO MLS level
  * @host_lvl: the host MLS level
  *
  * Description:
  * Perform a label mapping to translate a CIPSO level to the correct local MLS
  * level using the given DOI definition.  Returns zero on success, negative
  * values otherwise.
  *
  */
 static int cipso_v4_map_lvl_ntoh(const struct cipso_v4_doi *doi_def,
                  u32 net_lvl,
                  u32 *host_lvl)
 {
     struct cipso_v4_std_map_tbl *map_tbl;
 
     switch (doi_def->type) {
     case CIPSO_V4_MAP_PASS:
         *host_lvl = net_lvl;
         return 0;
     case CIPSO_V4_MAP_TRANS:
         map_tbl = doi_def->map.std;
         if (net_lvl < map_tbl->lvl.cipso_size &&
             map_tbl->lvl.cipso[net_lvl] < CIPSO_V4_INV_LVL) {
             *host_lvl = doi_def->map.std->lvl.cipso[net_lvl];
             return 0;
         }
         return -EPERM;
     }
 
     return -EINVAL;
 }
 
 /**
  * cipso_v4_map_cat_rbm_valid - Checks to see if the category bitmap is valid
  * @doi_def: the DOI definition
  * @bitmap: category bitmap
  * @bitmap_len: bitmap length in bytes
  *
  * Description:
  * Checks the given category bitmap against the given DOI definition and
  * returns a negative value if any of the categories in the bitmap do not have
  * a valid mapping and a zero value if all of the categories are valid.
  *
  */
 static int cipso_v4_map_cat_rbm_valid(const struct cipso_v4_doi *doi_def,
                       const unsigned char *bitmap,
                       u32 bitmap_len)
 {
     int cat = -1;
     u32 bitmap_len_bits = bitmap_len * 8;
     u32 cipso_cat_size;
     u32 *cipso_array;
 
     switch (doi_def->type) {
     case CIPSO_V4_MAP_PASS:
         return 0;
     case CIPSO_V4_MAP_TRANS:
         cipso_cat_size = doi_def->map.std->cat.cipso_size;
         cipso_array = doi_def->map.std->cat.cipso;
         for (;;) {
             cat = netlbl_bitmap_walk(bitmap,
                          bitmap_len_bits,
                          cat + 1,
                          1);
             if (cat < 0)
                 break;
             if (cat >= cipso_cat_size ||
                 cipso_array[cat] >= CIPSO_V4_INV_CAT)
                 return -EFAULT;
         }
 
         if (cat == -1)
             return 0;
         break;
     }
 
     return -EFAULT;
 }
 
 /**
  * cipso_v4_map_cat_rbm_hton - Perform a category mapping from host to network
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @net_cat: the zero'd out category bitmap in network/CIPSO format
  * @net_cat_len: the length of the CIPSO bitmap in bytes
  *
  * Description:
  * Perform a label mapping to translate a local MLS category bitmap to the
  * correct CIPSO bitmap using the given DOI definition.  Returns the minimum
  * size in bytes of the network bitmap on success, negative values otherwise.
  *
  */
 static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
                      const struct netlbl_lsm_secattr *secattr,
                      unsigned char *net_cat,
                      u32 net_cat_len)
 {
     int host_spot = -1;
     u32 net_spot = CIPSO_V4_INV_CAT;
     u32 net_spot_max = 0;
     u32 net_clen_bits = net_cat_len * 8;
     u32 host_cat_size = 0;
     u32 *host_cat_array = NULL;
 
     if (doi_def->type == CIPSO_V4_MAP_TRANS) {
         host_cat_size = doi_def->map.std->cat.local_size;
         host_cat_array = doi_def->map.std->cat.local;
     }
 
     for (;;) {
         host_spot = netlbl_catmap_walk(secattr->attr.mls.cat,
                            host_spot + 1);
         if (host_spot < 0)
             break;
 
         switch (doi_def->type) {
         case CIPSO_V4_MAP_PASS:
             net_spot = host_spot;
             break;
         case CIPSO_V4_MAP_TRANS:
             if (host_spot >= host_cat_size)
                 return -EPERM;
             net_spot = host_cat_array[host_spot];
             if (net_spot >= CIPSO_V4_INV_CAT)
                 return -EPERM;
             break;
         }
         if (net_spot >= net_clen_bits)
             return -ENOSPC;
         netlbl_bitmap_setbit(net_cat, net_spot, 1);
 
         if (net_spot > net_spot_max)
             net_spot_max = net_spot;
     }
 
     if (++net_spot_max % 8)
         return net_spot_max / 8 + 1;
     return net_spot_max / 8;
 }
 
 /**
  * cipso_v4_map_cat_rbm_ntoh - Perform a category mapping from network to host
  * @doi_def: the DOI definition
  * @net_cat: the category bitmap in network/CIPSO format
  * @net_cat_len: the length of the CIPSO bitmap in bytes
  * @secattr: the security attributes
  *
  * Description:
  * Perform a label mapping to translate a CIPSO bitmap to the correct local
  * MLS category bitmap using the given DOI definition.  Returns zero on
  * success, negative values on failure.
  *
  */
 static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
                      const unsigned char *net_cat,
                      u32 net_cat_len,
                      struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     int net_spot = -1;
     u32 host_spot = CIPSO_V4_INV_CAT;
     u32 net_clen_bits = net_cat_len * 8;
     u32 net_cat_size = 0;
     u32 *net_cat_array = NULL;
 
     if (doi_def->type == CIPSO_V4_MAP_TRANS) {
         net_cat_size = doi_def->map.std->cat.cipso_size;
         net_cat_array = doi_def->map.std->cat.cipso;
     }
 
     for (;;) {
         net_spot = netlbl_bitmap_walk(net_cat,
                           net_clen_bits,
                           net_spot + 1,
                           1);
         if (net_spot < 0) {
             if (net_spot == -2)
                 return -EFAULT;
             return 0;
         }
 
         switch (doi_def->type) {
         case CIPSO_V4_MAP_PASS:
             host_spot = net_spot;
             break;
         case CIPSO_V4_MAP_TRANS:
             if (net_spot >= net_cat_size)
                 return -EPERM;
             host_spot = net_cat_array[net_spot];
             if (host_spot >= CIPSO_V4_INV_CAT)
                 return -EPERM;
             break;
         }
         ret_val = netlbl_catmap_setbit(&secattr->attr.mls.cat,
                                host_spot,
                                GFP_ATOMIC);
         if (ret_val != 0)
             return ret_val;
     }
 
     return -EINVAL;
 }
 
 /**
  * cipso_v4_map_cat_enum_valid - Checks to see if the categories are valid
  * @doi_def: the DOI definition
  * @enumcat: category list
  * @enumcat_len: length of the category list in bytes
  *
  * Description:
  * Checks the given categories against the given DOI definition and returns a
  * negative value if any of the categories do not have a valid mapping and a
  * zero value if all of the categories are valid.
  *
  */
 static int cipso_v4_map_cat_enum_valid(const struct cipso_v4_doi *doi_def,
                        const unsigned char *enumcat,
                        u32 enumcat_len)
 {
     u16 cat;
     int cat_prev = -1;
     u32 iter;
 
     if (doi_def->type != CIPSO_V4_MAP_PASS || enumcat_len & 0x01)
         return -EFAULT;
 
     for (iter = 0; iter < enumcat_len; iter += 2) {
         cat = get_unaligned_be16(&enumcat[iter]);
         if (cat <= cat_prev)
             return -EFAULT;
         cat_prev = cat;
     }
 
     return 0;
 }
 
 /**
  * cipso_v4_map_cat_enum_hton - Perform a category mapping from host to network
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @net_cat: the zero'd out category list in network/CIPSO format
  * @net_cat_len: the length of the CIPSO category list in bytes
  *
  * Description:
  * Perform a label mapping to translate a local MLS category bitmap to the
  * correct CIPSO category list using the given DOI definition.   Returns the
  * size in bytes of the network category bitmap on success, negative values
  * otherwise.
  *
  */
 static int cipso_v4_map_cat_enum_hton(const struct cipso_v4_doi *doi_def,
                       const struct netlbl_lsm_secattr *secattr,
                       unsigned char *net_cat,
                       u32 net_cat_len)
 {
     int cat = -1;
     u32 cat_iter = 0;
 
     for (;;) {
         cat = netlbl_catmap_walk(secattr->attr.mls.cat, cat + 1);
         if (cat < 0)
             break;
         if ((cat_iter + 2) > net_cat_len)
             return -ENOSPC;
 
         *((__be16 *)&net_cat[cat_iter]) = htons(cat);
         cat_iter += 2;
     }
 
     return cat_iter;
 }
 
 /**
  * cipso_v4_map_cat_enum_ntoh - Perform a category mapping from network to host
  * @doi_def: the DOI definition
  * @net_cat: the category list in network/CIPSO format
  * @net_cat_len: the length of the CIPSO bitmap in bytes
  * @secattr: the security attributes
  *
  * Description:
  * Perform a label mapping to translate a CIPSO category list to the correct
  * local MLS category bitmap using the given DOI definition.  Returns zero on
  * success, negative values on failure.
  *
  */
 static int cipso_v4_map_cat_enum_ntoh(const struct cipso_v4_doi *doi_def,
                       const unsigned char *net_cat,
                       u32 net_cat_len,
                       struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     u32 iter;
 
     for (iter = 0; iter < net_cat_len; iter += 2) {
         ret_val = netlbl_catmap_setbit(&secattr->attr.mls.cat,
                          get_unaligned_be16(&net_cat[iter]),
                          GFP_ATOMIC);
         if (ret_val != 0)
             return ret_val;
     }
 
     return 0;
 }
 
 /**
  * cipso_v4_map_cat_rng_valid - Checks to see if the categories are valid
  * @doi_def: the DOI definition
  * @rngcat: category list
  * @rngcat_len: length of the category list in bytes
  *
  * Description:
  * Checks the given categories against the given DOI definition and returns a
  * negative value if any of the categories do not have a valid mapping and a
  * zero value if all of the categories are valid.
  *
  */
 static int cipso_v4_map_cat_rng_valid(const struct cipso_v4_doi *doi_def,
                       const unsigned char *rngcat,
                       u32 rngcat_len)
 {
     u16 cat_high;
     u16 cat_low;
     u32 cat_prev = CIPSO_V4_MAX_REM_CATS + 1;
     u32 iter;
 
     if (doi_def->type != CIPSO_V4_MAP_PASS || rngcat_len & 0x01)
         return -EFAULT;
 
     for (iter = 0; iter < rngcat_len; iter += 4) {
         cat_high = get_unaligned_be16(&rngcat[iter]);
         if ((iter + 4) <= rngcat_len)
             cat_low = get_unaligned_be16(&rngcat[iter + 2]);
         else
             cat_low = 0;
 
         if (cat_high > cat_prev)
             return -EFAULT;
 
         cat_prev = cat_low;
     }
 
     return 0;
 }
 
 /**
  * cipso_v4_map_cat_rng_hton - Perform a category mapping from host to network
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @net_cat: the zero'd out category list in network/CIPSO format
  * @net_cat_len: the length of the CIPSO category list in bytes
  *
  * Description:
  * Perform a label mapping to translate a local MLS category bitmap to the
  * correct CIPSO category list using the given DOI definition.   Returns the
  * size in bytes of the network category bitmap on success, negative values
  * otherwise.
  *
  */
 static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def,
                      const struct netlbl_lsm_secattr *secattr,
                      unsigned char *net_cat,
                      u32 net_cat_len)
 {
     int iter = -1;
     u16 array[CIPSO_V4_TAG_RNG_CAT_MAX * 2];
     u32 array_cnt = 0;
     u32 cat_size = 0;
 
     /* make sure we don't overflow the 'array[]' variable */
     if (net_cat_len >
         (CIPSO_V4_OPT_LEN_MAX - CIPSO_V4_HDR_LEN - CIPSO_V4_TAG_RNG_BLEN))
         return -ENOSPC;
 
     for (;;) {
         iter = netlbl_catmap_walk(secattr->attr.mls.cat, iter + 1);
         if (iter < 0)
             break;
         cat_size += (iter == 0 ? 0 : sizeof(u16));
         if (cat_size > net_cat_len)
             return -ENOSPC;
         array[array_cnt++] = iter;
 
         iter = netlbl_catmap_walkrng(secattr->attr.mls.cat, iter);
         if (iter < 0)
             return -EFAULT;
         cat_size += sizeof(u16);
         if (cat_size > net_cat_len)
             return -ENOSPC;
         array[array_cnt++] = iter;
     }
 
     for (iter = 0; array_cnt > 0;) {
         *((__be16 *)&net_cat[iter]) = htons(array[--array_cnt]);
         iter += 2;
         array_cnt--;
         if (array[array_cnt] != 0) {
             *((__be16 *)&net_cat[iter]) = htons(array[array_cnt]);
             iter += 2;
         }
     }
 
     return cat_size;
 }
 
 /**
  * cipso_v4_map_cat_rng_ntoh - Perform a category mapping from network to host
  * @doi_def: the DOI definition
  * @net_cat: the category list in network/CIPSO format
  * @net_cat_len: the length of the CIPSO bitmap in bytes
  * @secattr: the security attributes
  *
  * Description:
  * Perform a label mapping to translate a CIPSO category list to the correct
  * local MLS category bitmap using the given DOI definition.  Returns zero on
  * success, negative values on failure.
  *
  */
 static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def,
                      const unsigned char *net_cat,
                      u32 net_cat_len,
                      struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     u32 net_iter;
     u16 cat_low;
     u16 cat_high;
 
     for (net_iter = 0; net_iter < net_cat_len; net_iter += 4) {
         cat_high = get_unaligned_be16(&net_cat[net_iter]);
         if ((net_iter + 4) <= net_cat_len)
             cat_low = get_unaligned_be16(&net_cat[net_iter + 2]);
         else
             cat_low = 0;
 
         ret_val = netlbl_catmap_setrng(&secattr->attr.mls.cat,
                            cat_low,
                            cat_high,
                            GFP_ATOMIC);
         if (ret_val != 0)
             return ret_val;
     }
 
     return 0;
 }
 
 /*
  * Protocol Handling Functions
  */
 
 /**
  * cipso_v4_gentag_hdr - Generate a CIPSO option header
  * @doi_def: the DOI definition
  * @len: the total tag length in bytes, not including this header
  * @buf: the CIPSO option buffer
  *
  * Description:
  * Write a CIPSO header into the beginning of @buffer.
  *
  */
 static void cipso_v4_gentag_hdr(const struct cipso_v4_doi *doi_def,
                 unsigned char *buf,
                 u32 len)
 {
     buf[0] = IPOPT_CIPSO;
     buf[1] = CIPSO_V4_HDR_LEN + len;
     put_unaligned_be32(doi_def->doi, &buf[2]);
 }
 
 /**
  * cipso_v4_gentag_rbm - Generate a CIPSO restricted bitmap tag (type #1)
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @buffer: the option buffer
  * @buffer_len: length of buffer in bytes
  *
  * Description:
  * Generate a CIPSO option using the restricted bitmap tag, tag type #1.  The
  * actual buffer length may be larger than the indicated size due to
  * translation between host and network category bitmaps.  Returns the size of
  * the tag on success, negative values on failure.
  *
  */
 static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
                    const struct netlbl_lsm_secattr *secattr,
                    unsigned char *buffer,
                    u32 buffer_len)
 {
     int ret_val;
     u32 tag_len;
     u32 level;
 
     if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
         return -EPERM;
 
     ret_val = cipso_v4_map_lvl_hton(doi_def,
                     secattr->attr.mls.lvl,
                     &level);
     if (ret_val != 0)
         return ret_val;
 
     if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
         ret_val = cipso_v4_map_cat_rbm_hton(doi_def,
                             secattr,
                             &buffer[4],
                             buffer_len - 4);
         if (ret_val < 0)
             return ret_val;
 
         /* This will send packets using the "optimized" format when
          * possible as specified in  section 3.4.2.6 of the
          * CIPSO draft. */
         if (READ_ONCE(cipso_v4_rbm_optfmt) && ret_val > 0 &&
             ret_val <= 10)
             tag_len = 14;
         else
             tag_len = 4 + ret_val;
     } else
         tag_len = 4;
 
     buffer[0] = CIPSO_V4_TAG_RBITMAP;
     buffer[1] = tag_len;
     buffer[3] = level;
 
     return tag_len;
 }
 
 /**
  * cipso_v4_parsetag_rbm - Parse a CIPSO restricted bitmap tag
  * @doi_def: the DOI definition
  * @tag: the CIPSO tag
  * @secattr: the security attributes
  *
  * Description:
  * Parse a CIPSO restricted bitmap tag (tag type #1) and return the security
  * attributes in @secattr.  Return zero on success, negatives values on
  * failure.
  *
  */
 static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
                  const unsigned char *tag,
                  struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     u8 tag_len = tag[1];
     u32 level;
 
     ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
     if (ret_val != 0)
         return ret_val;
     secattr->attr.mls.lvl = level;
     secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
     if (tag_len > 4) {
         ret_val = cipso_v4_map_cat_rbm_ntoh(doi_def,
                             &tag[4],
                             tag_len - 4,
                             secattr);
         if (ret_val != 0) {
             netlbl_catmap_free(secattr->attr.mls.cat);
             return ret_val;
         }
 
         if (secattr->attr.mls.cat)
             secattr->flags |= NETLBL_SECATTR_MLS_CAT;
     }
 
     return 0;
 }
 
 /**
  * cipso_v4_gentag_enum - Generate a CIPSO enumerated tag (type #2)
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @buffer: the option buffer
  * @buffer_len: length of buffer in bytes
  *
  * Description:
  * Generate a CIPSO option using the enumerated tag, tag type #2.  Returns the
  * size of the tag on success, negative values on failure.
  *
  */
 static int cipso_v4_gentag_enum(const struct cipso_v4_doi *doi_def,
                 const struct netlbl_lsm_secattr *secattr,
                 unsigned char *buffer,
                 u32 buffer_len)
 {
     int ret_val;
     u32 tag_len;
     u32 level;
 
     if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
         return -EPERM;
 
     ret_val = cipso_v4_map_lvl_hton(doi_def,
                     secattr->attr.mls.lvl,
                     &level);
     if (ret_val != 0)
         return ret_val;
 
     if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
         ret_val = cipso_v4_map_cat_enum_hton(doi_def,
                              secattr,
                              &buffer[4],
                              buffer_len - 4);
         if (ret_val < 0)
             return ret_val;
 
         tag_len = 4 + ret_val;
     } else
         tag_len = 4;
 
     buffer[0] = CIPSO_V4_TAG_ENUM;
     buffer[1] = tag_len;
     buffer[3] = level;
 
     return tag_len;
 }
 
 /**
  * cipso_v4_parsetag_enum - Parse a CIPSO enumerated tag
  * @doi_def: the DOI definition
  * @tag: the CIPSO tag
  * @secattr: the security attributes
  *
  * Description:
  * Parse a CIPSO enumerated tag (tag type #2) and return the security
  * attributes in @secattr.  Return zero on success, negatives values on
  * failure.
  *
  */
 static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
                   const unsigned char *tag,
                   struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     u8 tag_len = tag[1];
     u32 level;
 
     ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
     if (ret_val != 0)
         return ret_val;
     secattr->attr.mls.lvl = level;
     secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
     if (tag_len > 4) {
         ret_val = cipso_v4_map_cat_enum_ntoh(doi_def,
                              &tag[4],
                              tag_len - 4,
                              secattr);
         if (ret_val != 0) {
             netlbl_catmap_free(secattr->attr.mls.cat);
             return ret_val;
         }
 
         secattr->flags |= NETLBL_SECATTR_MLS_CAT;
     }
 
     return 0;
 }
 
 /**
  * cipso_v4_gentag_rng - Generate a CIPSO ranged tag (type #5)
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @buffer: the option buffer
  * @buffer_len: length of buffer in bytes
  *
  * Description:
  * Generate a CIPSO option using the ranged tag, tag type #5.  Returns the
  * size of the tag on success, negative values on failure.
  *
  */
 static int cipso_v4_gentag_rng(const struct cipso_v4_doi *doi_def,
                    const struct netlbl_lsm_secattr *secattr,
                    unsigned char *buffer,
                    u32 buffer_len)
 {
     int ret_val;
     u32 tag_len;
     u32 level;
 
     if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
         return -EPERM;
 
     ret_val = cipso_v4_map_lvl_hton(doi_def,
                     secattr->attr.mls.lvl,
                     &level);
     if (ret_val != 0)
         return ret_val;
 
     if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
         ret_val = cipso_v4_map_cat_rng_hton(doi_def,
                             secattr,
                             &buffer[4],
                             buffer_len - 4);
         if (ret_val < 0)
             return ret_val;
 
         tag_len = 4 + ret_val;
     } else
         tag_len = 4;
 
     buffer[0] = CIPSO_V4_TAG_RANGE;
     buffer[1] = tag_len;
     buffer[3] = level;
 
     return tag_len;
 }
 
 /**
  * cipso_v4_parsetag_rng - Parse a CIPSO ranged tag
  * @doi_def: the DOI definition
  * @tag: the CIPSO tag
  * @secattr: the security attributes
  *
  * Description:
  * Parse a CIPSO ranged tag (tag type #5) and return the security attributes
  * in @secattr.  Return zero on success, negatives values on failure.
  *
  */
 static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
                  const unsigned char *tag,
                  struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     u8 tag_len = tag[1];
     u32 level;
 
     ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
     if (ret_val != 0)
         return ret_val;
     secattr->attr.mls.lvl = level;
     secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
     if (tag_len > 4) {
         ret_val = cipso_v4_map_cat_rng_ntoh(doi_def,
                             &tag[4],
                             tag_len - 4,
                             secattr);
         if (ret_val != 0) {
             netlbl_catmap_free(secattr->attr.mls.cat);
             return ret_val;
         }
 
         if (secattr->attr.mls.cat)
             secattr->flags |= NETLBL_SECATTR_MLS_CAT;
     }
 
     return 0;
 }
 
 /**
  * cipso_v4_gentag_loc - Generate a CIPSO local tag (non-standard)
  * @doi_def: the DOI definition
  * @secattr: the security attributes
  * @buffer: the option buffer
  * @buffer_len: length of buffer in bytes
  *
  * Description:
  * Generate a CIPSO option using the local tag.  Returns the size of the tag
  * on success, negative values on failure.
  *
  */
 static int cipso_v4_gentag_loc(const struct cipso_v4_doi *doi_def,
                    const struct netlbl_lsm_secattr *secattr,
                    unsigned char *buffer,
                    u32 buffer_len)
 {
     if (!(secattr->flags & NETLBL_SECATTR_SECID))
         return -EPERM;
 
     buffer[0] = CIPSO_V4_TAG_LOCAL;
     buffer[1] = CIPSO_V4_TAG_LOC_BLEN;
     *(u32 *)&buffer[2] = secattr->attr.secid;
 
     return CIPSO_V4_TAG_LOC_BLEN;
 }
 
 /**
  * cipso_v4_parsetag_loc - Parse a CIPSO local tag
  * @doi_def: the DOI definition
  * @tag: the CIPSO tag
  * @secattr: the security attributes
  *
  * Description:
  * Parse a CIPSO local tag and return the security attributes in @secattr.
  * Return zero on success, negatives values on failure.
  *
  */
 static int cipso_v4_parsetag_loc(const struct cipso_v4_doi *doi_def,
                  const unsigned char *tag,
                  struct netlbl_lsm_secattr *secattr)
 {
     secattr->attr.secid = *(u32 *)&tag[2];
     secattr->flags |= NETLBL_SECATTR_SECID;
 
     return 0;
 }
 
 /**
  * cipso_v4_optptr - Find the CIPSO option in the packet
  * @skb: the packet
  *
  * Description:
  * Parse the packet's IP header looking for a CIPSO option.  Returns a pointer
  * to the start of the CIPSO option on success, NULL if one is not found.
  *
  */
 unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
 {
     const struct iphdr *iph = ip_hdr(skb);
     unsigned char *optptr = (unsigned char *)&(ip_hdr(skb)[1]);
     int optlen;
     int taglen;
 
     for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 1; ) {
         switch (optptr[0]) {
         case IPOPT_END:
             return NULL;
         case IPOPT_NOOP:
             taglen = 1;
             break;
         default:
             taglen = optptr[1];
         }
         if (!taglen || taglen > optlen)
             return NULL;
         if (optptr[0] == IPOPT_CIPSO)
             return optptr;
 
         optlen -= taglen;
         optptr += taglen;
     }
 
     return NULL;
 }
 
 /**
  * cipso_v4_validate - Validate a CIPSO option
  * @skb: the packet
  * @option: the start of the option, on error it is set to point to the error
  *
  * Description:
  * This routine is called to validate a CIPSO option, it checks all of the
  * fields to ensure that they are at least valid, see the draft snippet below
  * for details.  If the option is valid then a zero value is returned and
  * the value of @option is unchanged.  If the option is invalid then a
  * non-zero value is returned and @option is adjusted to point to the
  * offending portion of the option.  From the IETF draft ...
  *
  *  "If any field within the CIPSO options, such as the DOI identifier, is not
  *   recognized the IP datagram is discarded and an ICMP 'parameter problem'
  *   (type 12) is generated and returned.  The ICMP code field is set to 'bad
  *   parameter' (code 0) and the pointer is set to the start of the CIPSO field
  *   that is unrecognized."
  *
  */
 int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
 {
     unsigned char *opt = *option;
     unsigned char *tag;
     unsigned char opt_iter;
     unsigned char err_offset = 0;
     u8 opt_len;
     u8 tag_len;
     struct cipso_v4_doi *doi_def = NULL;
     u32 tag_iter;
 
     /* caller already checks for length values that are too large */
     opt_len = opt[1];
     if (opt_len < 8) {
         err_offset = 1;
         goto validate_return;
     }
 
     rcu_read_lock();
     doi_def = cipso_v4_doi_search(get_unaligned_be32(&opt[2]));
     if (!doi_def) {
         err_offset = 2;
         goto validate_return_locked;
     }
 
     opt_iter = CIPSO_V4_HDR_LEN;
     tag = opt + opt_iter;
     while (opt_iter < opt_len) {
         for (tag_iter = 0; doi_def->tags[tag_iter] != tag[0];)
             if (doi_def->tags[tag_iter] == CIPSO_V4_TAG_INVALID ||
                 ++tag_iter == CIPSO_V4_TAG_MAXCNT) {
                 err_offset = opt_iter;
                 goto validate_return_locked;
             }
 
         if (opt_iter + 1 == opt_len) {
             err_offset = opt_iter;
             goto validate_return_locked;
         }
         tag_len = tag[1];
         if (tag_len > (opt_len - opt_iter)) {
             err_offset = opt_iter + 1;
             goto validate_return_locked;
         }
 
         switch (tag[0]) {
         case CIPSO_V4_TAG_RBITMAP:
             if (tag_len < CIPSO_V4_TAG_RBM_BLEN) {
                 err_offset = opt_iter + 1;
                 goto validate_return_locked;
             }
 
             /* We are already going to do all the verification
              * necessary at the socket layer so from our point of
              * view it is safe to turn these checks off (and less
              * work), however, the CIPSO draft says we should do
              * all the CIPSO validations here but it doesn't
              * really specify _exactly_ what we need to validate
              * ... so, just make it a sysctl tunable. */
             if (READ_ONCE(cipso_v4_rbm_strictvalid)) {
                 if (cipso_v4_map_lvl_valid(doi_def,
                                tag[3]) < 0) {
                     err_offset = opt_iter + 3;
                     goto validate_return_locked;
                 }
                 if (tag_len > CIPSO_V4_TAG_RBM_BLEN &&
                     cipso_v4_map_cat_rbm_valid(doi_def,
                                 &tag[4],
                                 tag_len - 4) < 0) {
                     err_offset = opt_iter + 4;
                     goto validate_return_locked;
                 }
             }
             break;
         case CIPSO_V4_TAG_ENUM:
             if (tag_len < CIPSO_V4_TAG_ENUM_BLEN) {
                 err_offset = opt_iter + 1;
                 goto validate_return_locked;
             }
 
             if (cipso_v4_map_lvl_valid(doi_def,
                            tag[3]) < 0) {
                 err_offset = opt_iter + 3;
                 goto validate_return_locked;
             }
             if (tag_len > CIPSO_V4_TAG_ENUM_BLEN &&
                 cipso_v4_map_cat_enum_valid(doi_def,
                             &tag[4],
                             tag_len - 4) < 0) {
                 err_offset = opt_iter + 4;
                 goto validate_return_locked;
             }
             break;
         case CIPSO_V4_TAG_RANGE:
             if (tag_len < CIPSO_V4_TAG_RNG_BLEN) {
                 err_offset = opt_iter + 1;
                 goto validate_return_locked;
             }
 
             if (cipso_v4_map_lvl_valid(doi_def,
                            tag[3]) < 0) {
                 err_offset = opt_iter + 3;
                 goto validate_return_locked;
             }
             if (tag_len > CIPSO_V4_TAG_RNG_BLEN &&
                 cipso_v4_map_cat_rng_valid(doi_def,
                                &tag[4],
                                tag_len - 4) < 0) {
                 err_offset = opt_iter + 4;
                 goto validate_return_locked;
             }
             break;
         case CIPSO_V4_TAG_LOCAL:
             /* This is a non-standard tag that we only allow for
              * local connections, so if the incoming interface is
              * not the loopback device drop the packet. Further,
              * there is no legitimate reason for setting this from
              * userspace so reject it if skb is NULL. */
             if (!skb || !(skb->dev->flags & IFF_LOOPBACK)) {
                 err_offset = opt_iter;
                 goto validate_return_locked;
             }
             if (tag_len != CIPSO_V4_TAG_LOC_BLEN) {
                 err_offset = opt_iter + 1;
                 goto validate_return_locked;
             }
             break;
         default:
             err_offset = opt_iter;
             goto validate_return_locked;
         }
 
         tag += tag_len;
         opt_iter += tag_len;
     }
 
 validate_return_locked:
     rcu_read_unlock();
 validate_return:
     *option = opt + err_offset;
     return err_offset;
 }
 
 /**
  * cipso_v4_error - Send the correct response for a bad packet
  * @skb: the packet
  * @error: the error code
  * @gateway: CIPSO gateway flag
  *
  * Description:
  * Based on the error code given in @error, send an ICMP error message back to
  * the originating host.  From the IETF draft ...
  *
  *  "If the contents of the CIPSO [option] are valid but the security label is
  *   outside of the configured host or port label range, the datagram is
  *   discarded and an ICMP 'destination unreachable' (type 3) is generated and
  *   returned.  The code field of the ICMP is set to 'communication with
  *   destination network administratively prohibited' (code 9) or to
  *   'communication with destination host administratively prohibited'
  *   (code 10).  The value of the code is dependent on whether the originator
  *   of the ICMP message is acting as a CIPSO host or a CIPSO gateway.  The
  *   recipient of the ICMP message MUST be able to handle either value.  The
  *   same procedure is performed if a CIPSO [option] can not be added to an
  *   IP packet because it is too large to fit in the IP options area."
  *
  *  "If the error is triggered by receipt of an ICMP message, the message is
  *   discarded and no response is permitted (consistent with general ICMP
  *   processing rules)."
  *
  */
 void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
 {
     unsigned char optbuf[sizeof(struct ip_options) + 40];
     struct ip_options *opt = (struct ip_options *)optbuf;
     int res;
 
     if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
         return;
 
     /*
      * We might be called above the IP layer,
      * so we can not use icmp_send and IPCB here.
      */
 
     memset(opt, 0, sizeof(struct ip_options));
     opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
     rcu_read_lock();
     res = __ip_options_compile(dev_net(skb->dev), opt, skb, NULL);
     rcu_read_unlock();
 
     if (res)
         return;
 
     if (gateway)
         __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0, opt);
     else
         __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0, opt);
 }
 
 /**
  * cipso_v4_genopt - Generate a CIPSO option
  * @buf: the option buffer
  * @buf_len: the size of opt_buf
  * @doi_def: the CIPSO DOI to use
  * @secattr: the security attributes
  *
  * Description:
  * Generate a CIPSO option using the DOI definition and security attributes
  * passed to the function.  Returns the length of the option on success and
  * negative values on failure.
  *
  */
 static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
                const struct cipso_v4_doi *doi_def,
                const struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     u32 iter;
 
     if (buf_len <= CIPSO_V4_HDR_LEN)
         return -ENOSPC;
 
     /* XXX - This code assumes only one tag per CIPSO option which isn't
      * really a good assumption to make but since we only support the MAC
      * tags right now it is a safe assumption. */
     iter = 0;
     do {
         memset(buf, 0, buf_len);
         switch (doi_def->tags[iter]) {
         case CIPSO_V4_TAG_RBITMAP:
             ret_val = cipso_v4_gentag_rbm(doi_def,
                            secattr,
                            &buf[CIPSO_V4_HDR_LEN],
                            buf_len - CIPSO_V4_HDR_LEN);
             break;
         case CIPSO_V4_TAG_ENUM:
             ret_val = cipso_v4_gentag_enum(doi_def,
                            secattr,
                            &buf[CIPSO_V4_HDR_LEN],
                            buf_len - CIPSO_V4_HDR_LEN);
             break;
         case CIPSO_V4_TAG_RANGE:
             ret_val = cipso_v4_gentag_rng(doi_def,
                            secattr,
                            &buf[CIPSO_V4_HDR_LEN],
                            buf_len - CIPSO_V4_HDR_LEN);
             break;
         case CIPSO_V4_TAG_LOCAL:
             ret_val = cipso_v4_gentag_loc(doi_def,
                            secattr,
                            &buf[CIPSO_V4_HDR_LEN],
                            buf_len - CIPSO_V4_HDR_LEN);
             break;
         default:
             return -EPERM;
         }
 
         iter++;
     } while (ret_val < 0 &&
          iter < CIPSO_V4_TAG_MAXCNT &&
          doi_def->tags[iter] != CIPSO_V4_TAG_INVALID);
     if (ret_val < 0)
         return ret_val;
     cipso_v4_gentag_hdr(doi_def, buf, ret_val);
     return CIPSO_V4_HDR_LEN + ret_val;
 }
 
 /**
  * cipso_v4_sock_setattr - Add a CIPSO option to a socket
  * @sk: the socket
  * @doi_def: the CIPSO DOI to use
  * @secattr: the specific security attributes of the socket
  *
  * Description:
  * Set the CIPSO option on the given socket using the DOI definition and
  * security attributes passed to the function.  This function requires
  * exclusive access to @sk, which means it either needs to be in the
  * process of being created or locked.  Returns zero on success and negative
  * values on failure.
  *
  */
 int cipso_v4_sock_setattr(struct sock *sk,
               const struct cipso_v4_doi *doi_def,
               const struct netlbl_lsm_secattr *secattr)
 {
     int ret_val = -EPERM;
     unsigned char *buf = NULL;
     u32 buf_len;
     u32 opt_len;
     struct ip_options_rcu *old, *opt = NULL;
     struct inet_sock *sk_inet;
     struct inet_connection_sock *sk_conn;
 
     /* In the case of sock_create_lite(), the sock->sk field is not
      * defined yet but it is not a problem as the only users of these
      * "lite" PF_INET sockets are functions which do an accept() call
      * afterwards so we will label the socket as part of the accept(). */
     if (!sk)
         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) {
         ret_val = -ENOMEM;
         goto socket_setattr_failure;
     }
 
     ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
     if (ret_val < 0)
         goto socket_setattr_failure;
     buf_len = ret_val;
 
     /* We can't use ip_options_get() directly because it makes a call to
      * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
      * we won't always have CAP_NET_RAW even though we _always_ want to
      * set the IPOPT_CIPSO option. */
     opt_len = (buf_len + 3) & ~3;
     opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
     if (!opt) {
         ret_val = -ENOMEM;
         goto socket_setattr_failure;
     }
     memcpy(opt->opt.__data, buf, buf_len);
     opt->opt.optlen = opt_len;
     opt->opt.cipso = sizeof(struct iphdr);
     kfree(buf);
     buf = NULL;
 
     sk_inet = inet_sk(sk);
 
     old = rcu_dereference_protected(sk_inet->inet_opt,
                     lockdep_sock_is_held(sk));
     if (sk_inet->is_icsk) {
         sk_conn = inet_csk(sk);
         if (old)
             sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
         sk_conn->icsk_ext_hdr_len += opt->opt.optlen;
         sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
     }
     rcu_assign_pointer(sk_inet->inet_opt, opt);
     if (old)
         kfree_rcu(old, rcu);
 
     return 0;
 
 socket_setattr_failure:
     kfree(buf);
     kfree(opt);
     return ret_val;
 }
 
 /**
  * cipso_v4_req_setattr - Add a CIPSO option to a connection request socket
  * @req: the connection request socket
  * @doi_def: the CIPSO DOI to use
  * @secattr: the specific security attributes of the socket
  *
  * Description:
  * Set the CIPSO option on the given socket using the DOI definition and
  * security attributes passed to the function.  Returns zero on success and
  * negative values on failure.
  *
  */
 int cipso_v4_req_setattr(struct request_sock *req,
              const struct cipso_v4_doi *doi_def,
              const struct netlbl_lsm_secattr *secattr)
 {
     int ret_val = -EPERM;
     unsigned char *buf = NULL;
     u32 buf_len;
     u32 opt_len;
     struct ip_options_rcu *opt = NULL;
     struct inet_request_sock *req_inet;
 
     /* We allocate the maximum CIPSO option size here so we are probably
      * being a little wasteful, but it makes our life _much_ easier later
      * on and after all we are only talking about 40 bytes. */
     buf_len = CIPSO_V4_OPT_LEN_MAX;
     buf = kmalloc(buf_len, GFP_ATOMIC);
     if (!buf) {
         ret_val = -ENOMEM;
         goto req_setattr_failure;
     }
 
     ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
     if (ret_val < 0)
         goto req_setattr_failure;
     buf_len = ret_val;
 
     /* We can't use ip_options_get() directly because it makes a call to
      * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
      * we won't always have CAP_NET_RAW even though we _always_ want to
      * set the IPOPT_CIPSO option. */
     opt_len = (buf_len + 3) & ~3;
     opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
     if (!opt) {
         ret_val = -ENOMEM;
         goto req_setattr_failure;
     }
     memcpy(opt->opt.__data, buf, buf_len);
     opt->opt.optlen = opt_len;
     opt->opt.cipso = sizeof(struct iphdr);
     kfree(buf);
     buf = NULL;
 
     req_inet = inet_rsk(req);
     opt = xchg((__force struct ip_options_rcu **)&req_inet->ireq_opt, opt);
     if (opt)
         kfree_rcu(opt, rcu);
 
     return 0;
 
 req_setattr_failure:
     kfree(buf);
     kfree(opt);
     return ret_val;
 }
 
 /**
  * cipso_v4_delopt - Delete the CIPSO option from a set of IP options
  * @opt_ptr: IP option pointer
  *
  * Description:
  * Deletes the CIPSO IP option from a set of IP options and makes the necessary
  * adjustments to the IP option structure.  Returns zero on success, negative
  * values on failure.
  *
  */
 static int cipso_v4_delopt(struct ip_options_rcu __rcu **opt_ptr)
 {
     struct ip_options_rcu *opt = rcu_dereference_protected(*opt_ptr, 1);
     int hdr_delta = 0;
 
     if (!opt || opt->opt.cipso == 0)
         return 0;
     if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) {
         u8 cipso_len;
         u8 cipso_off;
         unsigned char *cipso_ptr;
         int iter;
         int optlen_new;
 
         cipso_off = opt->opt.cipso - sizeof(struct iphdr);
         cipso_ptr = &opt->opt.__data[cipso_off];
         cipso_len = cipso_ptr[1];
 
         if (opt->opt.srr > opt->opt.cipso)
             opt->opt.srr -= cipso_len;
         if (opt->opt.rr > opt->opt.cipso)
             opt->opt.rr -= cipso_len;
         if (opt->opt.ts > opt->opt.cipso)
             opt->opt.ts -= cipso_len;
         if (opt->opt.router_alert > opt->opt.cipso)
             opt->opt.router_alert -= cipso_len;
         opt->opt.cipso = 0;
 
         memmove(cipso_ptr, cipso_ptr + cipso_len,
             opt->opt.optlen - cipso_off - cipso_len);
 
         /* determining the new total option length is tricky because of
          * the padding necessary, the only thing i can think to do at
          * this point is walk the options one-by-one, skipping the
          * padding at the end to determine the actual option size and
          * from there we can determine the new total option length */
         iter = 0;
         optlen_new = 0;
         while (iter < opt->opt.optlen)
             if (opt->opt.__data[iter] != IPOPT_NOP) {
                 iter += opt->opt.__data[iter + 1];
                 optlen_new = iter;
             } else
                 iter++;
         hdr_delta = opt->opt.optlen;
         opt->opt.optlen = (optlen_new + 3) & ~3;
         hdr_delta -= opt->opt.optlen;
     } else {
         /* only the cipso option was present on the socket so we can
          * remove the entire option struct */
         *opt_ptr = NULL;
         hdr_delta = opt->opt.optlen;
         kfree_rcu(opt, rcu);
     }
 
     return hdr_delta;
 }
 
 /**
  * cipso_v4_sock_delattr - Delete the CIPSO option from a socket
  * @sk: the socket
  *
  * Description:
  * Removes the CIPSO option from a socket, if present.
  *
  */
 void cipso_v4_sock_delattr(struct sock *sk)
 {
     struct inet_sock *sk_inet;
     int hdr_delta;
 
     sk_inet = inet_sk(sk);
 
     hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);
     if (sk_inet->is_icsk && hdr_delta > 0) {
         struct inet_connection_sock *sk_conn = inet_csk(sk);
         sk_conn->icsk_ext_hdr_len -= hdr_delta;
         sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
     }
 }
 
 /**
  * cipso_v4_req_delattr - Delete the CIPSO option from a request socket
  * @req: the request socket
  *
  * Description:
  * Removes the CIPSO option from a request socket, if present.
  *
  */
 void cipso_v4_req_delattr(struct request_sock *req)
 {
     cipso_v4_delopt(&inet_rsk(req)->ireq_opt);
 }
 
 /**
  * cipso_v4_getattr - Helper function for the cipso_v4_*_getattr functions
  * @cipso: the CIPSO v4 option
  * @secattr: the security attributes
  *
  * Description:
  * Inspect @cipso and return the security attributes in @secattr.  Returns zero
  * on success and negative values on failure.
  *
  */
 int cipso_v4_getattr(const unsigned char *cipso,
              struct netlbl_lsm_secattr *secattr)
 {
     int ret_val = -ENOMSG;
     u32 doi;
     struct cipso_v4_doi *doi_def;
 
     if (cipso_v4_cache_check(cipso, cipso[1], secattr) == 0)
         return 0;
 
     doi = get_unaligned_be32(&cipso[2]);
     rcu_read_lock();
     doi_def = cipso_v4_doi_search(doi);
     if (!doi_def)
         goto getattr_return;
     /* XXX - This code assumes only one tag per CIPSO option which isn't
      * really a good assumption to make but since we only support the MAC
      * tags right now it is a safe assumption. */
     switch (cipso[6]) {
     case CIPSO_V4_TAG_RBITMAP:
         ret_val = cipso_v4_parsetag_rbm(doi_def, &cipso[6], secattr);
         break;
     case CIPSO_V4_TAG_ENUM:
         ret_val = cipso_v4_parsetag_enum(doi_def, &cipso[6], secattr);
         break;
     case CIPSO_V4_TAG_RANGE:
         ret_val = cipso_v4_parsetag_rng(doi_def, &cipso[6], secattr);
         break;
     case CIPSO_V4_TAG_LOCAL:
         ret_val = cipso_v4_parsetag_loc(doi_def, &cipso[6], secattr);
         break;
     }
     if (ret_val == 0)
         secattr->type = NETLBL_NLTYPE_CIPSOV4;
 
 getattr_return:
     rcu_read_unlock();
     return ret_val;
 }
 
 /**
  * cipso_v4_sock_getattr - Get the security attributes from a sock
  * @sk: the sock
  * @secattr: the security attributes
  *
  * Description:
  * Query @sk to see if there is a CIPSO option attached to the sock and if
  * there is return the CIPSO security attributes in @secattr.  This function
  * requires that @sk be locked, or privately held, but it does not do any
  * locking itself.  Returns zero on success and negative values on failure.
  *
  */
 int cipso_v4_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
 {
     struct ip_options_rcu *opt;
     int res = -ENOMSG;
 
     rcu_read_lock();
     opt = rcu_dereference(inet_sk(sk)->inet_opt);
     if (opt && opt->opt.cipso)
         res = cipso_v4_getattr(opt->opt.__data +
                         opt->opt.cipso -
                         sizeof(struct iphdr),
                        secattr);
     rcu_read_unlock();
     return res;
 }
 
 /**
  * cipso_v4_skbuff_setattr - Set the CIPSO option on a packet
  * @skb: the packet
  * @doi_def: the DOI structure
  * @secattr: the security attributes
  *
  * Description:
  * Set the CIPSO option on the given packet based on the security attributes.
  * Returns a pointer to the IP header on success and NULL on failure.
  *
  */
 int cipso_v4_skbuff_setattr(struct sk_buff *skb,
                 const struct cipso_v4_doi *doi_def,
                 const struct netlbl_lsm_secattr *secattr)
 {
     int ret_val;
     struct iphdr *iph;
     struct ip_options *opt = &IPCB(skb)->opt;
     unsigned char buf[CIPSO_V4_OPT_LEN_MAX];
     u32 buf_len = CIPSO_V4_OPT_LEN_MAX;
     u32 opt_len;
     int len_delta;
 
     ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
     if (ret_val < 0)
         return ret_val;
     buf_len = ret_val;
     opt_len = (buf_len + 3) & ~3;
 
     /* we overwrite any existing options to ensure that we have enough
      * room for the CIPSO option, the reason is that we _need_ to guarantee
      * that the security label is applied to the packet - we do the same
      * thing when using the socket options and it hasn't caused a problem,
      * if we need to we can always revisit this choice later */
 
     len_delta = opt_len - opt->optlen;
     /* if we don't ensure enough headroom we could panic on the skb_push()
      * call below so make sure we have enough, we are also "mangling" the
      * packet so we should probably do a copy-on-write call anyway */
     ret_val = skb_cow(skb, skb_headroom(skb) + len_delta);
     if (ret_val < 0)
         return ret_val;
 
     if (len_delta > 0) {
         /* we assume that the header + opt->optlen have already been
          * "pushed" in ip_options_build() or similar */
         iph = ip_hdr(skb);
         skb_push(skb, len_delta);
         memmove((char *)iph - len_delta, iph, iph->ihl << 2);
         skb_reset_network_header(skb);
         iph = ip_hdr(skb);
     } else if (len_delta < 0) {
         iph = ip_hdr(skb);
         memset(iph + 1, IPOPT_NOP, opt->optlen);
     } else
         iph = ip_hdr(skb);
 
     if (opt->optlen > 0)
         memset(opt, 0, sizeof(*opt));
     opt->optlen = opt_len;
     opt->cipso = sizeof(struct iphdr);
     opt->is_changed = 1;
 
     /* we have to do the following because we are being called from a
      * netfilter hook which means the packet already has had the header
      * fields populated and the checksum calculated - yes this means we
      * are doing more work than needed but we do it to keep the core
      * stack clean and tidy */
     memcpy(iph + 1, buf, buf_len);
     if (opt_len > buf_len)
         memset((char *)(iph + 1) + buf_len, 0, opt_len - buf_len);
     if (len_delta != 0) {
         iph->ihl = 5 + (opt_len >> 2);
         iph->tot_len = htons(skb->len);
     }
     ip_send_check(iph);
 
     return 0;
 }
 
 /**
  * cipso_v4_skbuff_delattr - Delete any CIPSO options from a packet
  * @skb: the packet
  *
  * Description:
  * Removes any and all CIPSO options from the given packet.  Returns zero on
  * success, negative values on failure.
  *
  */
 int cipso_v4_skbuff_delattr(struct sk_buff *skb)
 {
     int ret_val;
     struct iphdr *iph;
     struct ip_options *opt = &IPCB(skb)->opt;
     unsigned char *cipso_ptr;
 
     if (opt->cipso == 0)
         return 0;
 
     /* since we are changing the packet we should make a copy */
     ret_val = skb_cow(skb, skb_headroom(skb));
     if (ret_val < 0)
         return ret_val;
 
     /* the easiest thing to do is just replace the cipso option with noop
      * options since we don't change the size of the packet, although we
      * still need to recalculate the checksum */
 
     iph = ip_hdr(skb);
     cipso_ptr = (unsigned char *)iph + opt->cipso;
     memset(cipso_ptr, IPOPT_NOOP, cipso_ptr[1]);
     opt->cipso = 0;
     opt->is_changed = 1;
 
     ip_send_check(iph);
 
     return 0;
 }
 
 /*
  * 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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