Initial import

1 files changed, 2357 insertions, 0 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
new file mode 100644
index 000000000..bdb2a07ec
--- /dev/null
+++ b/net/ipv4/cipso_ipv4.c
@@ -0,0 +1,2357 @@
+/*
+ * CIPSO - Commercial IP Security Option
+ *
+ * This is an implementation of the CIPSO 2.2 protocol as specified in
+ * draft-ietf-cipso-ipsecurity-01.txt with additional tag types as found in
+ * FIPS-188.  While CIPSO never became a full IETF RFC standard many vendors
+ * have chosen to adopt the protocol and over the years it has become a
+ * de-facto standard for labeled networking.
+ *
+ * The CIPSO draft specification can be found in the kernel's Documentation
+ * directory as well as the following URL:
+ *   http://tools.ietf.org/id/draft-ietf-cipso-ipsecurity-01.txt
+ * The FIPS-188 specification can be found at the following URL:
+ *   http://www.itl.nist.gov/fipspubs/fip188.htm
+ *
+ * Author: Paul Moore <paul.moore@hp.com>
+ *
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008
+ *
+ * This program is free software;  you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY;  without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program;  if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#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 = 0;
+int cipso_v4_rbm_strictvalid = 1;
+
+/*
+ * Protocol Constants
+ */
+
+/* Maximum size of the CIPSO IP option, derived from the fact that the maximum
+ * IPv4 header size is 60 bytes and the base IPv4 header is 20 bytes long. */
+#define CIPSO_V4_OPT_LEN_MAX          40
+
+/* Length of the base CIPSO option, this includes the option type (1 byte), the
+ * option length (1 byte), and the DOI (4 bytes). */
+#define CIPSO_V4_HDR_LEN              6
+
+/* Base length of the restrictive category bitmap tag (tag #1). */
+#define CIPSO_V4_TAG_RBM_BLEN         4
+
+/* Base length of the enumerated category tag (tag #2). */
+#define CIPSO_V4_TAG_ENUM_BLEN        4
+
+/* Base length of the ranged categories bitmap tag (tag #5). */
+#define CIPSO_V4_TAG_RNG_BLEN         4
+/* The maximum number of category ranges permitted in the ranged category tag
+ * (tag #5).  You may note that the IETF draft states that the maximum number
+ * of category ranges is 7, but if the low end of the last category range is
+ * zero then it is possible to fit 8 category ranges because the zero should
+ * be omitted. */
+#define CIPSO_V4_TAG_RNG_CAT_MAX      8
+
+/* Base length of the local tag (non-standard tag).
+ *  Tag definition (may change between kernel versions)
+ *
+ * 0          8          16         24         32
+ * +----------+----------+----------+----------+
+ * | 10000000 | 00000110 | 32-bit secid value  |
+ * +----------+----------+----------+----------+
+ * | in (host byte order)|
+ * +----------+----------+
+ *
+ */
+#define CIPSO_V4_TAG_LOC_BLEN         6
+
+/*
+ * Helper Functions
+ */
+
+/**
+ * cipso_v4_bitmap_walk - Walk a bitmap looking for a bit
+ * @bitmap: the bitmap
+ * @bitmap_len: length in bits
+ * @offset: starting offset
+ * @state: if non-zero, look for a set (1) bit else look for a cleared (0) bit
+ *
+ * Description:
+ * Starting at @offset, walk the bitmap from left to right until either the
+ * desired bit is found or we reach the end.  Return the bit offset, -1 if
+ * not found, or -2 if error.
+ */
+static int cipso_v4_bitmap_walk(const unsigned char *bitmap,
+				u32 bitmap_len,
+				u32 offset,
+				u8 state)
+{
+	u32 bit_spot;
+	u32 byte_offset;
+	unsigned char bitmask;
+	unsigned char byte;
+
+	/* gcc always rounds to zero when doing integer division */
+	byte_offset = offset / 8;
+	byte = bitmap[byte_offset];
+	bit_spot = offset;
+	bitmask = 0x80 >> (offset % 8);
+
+	while (bit_spot < bitmap_len) {
+		if ((state && (byte & bitmask) == bitmask) ||
+		    (state == 0 && (byte & bitmask) == 0))
+			return bit_spot;
+
+		bit_spot++;
+		bitmask >>= 1;
+		if (bitmask == 0) {
+			byte = bitmap[++byte_offset];
+			bitmask = 0x80;
+		}
+	}
+
+	return -1;
+}
+
+/**
+ * cipso_v4_bitmap_setbit - Sets a single bit in a bitmap
+ * @bitmap: the bitmap
+ * @bit: the bit
+ * @state: if non-zero, set the bit (1) else clear the bit (0)
+ *
+ * Description:
+ * Set a single bit in the bitmask.  Returns zero on success, negative values
+ * on error.
+ */
+static void cipso_v4_bitmap_setbit(unsigned char *bitmap,
+				   u32 bit,
+				   u8 state)
+{
+	u32 byte_spot;
+	u8 bitmask;
+
+	/* gcc always rounds to zero when doing integer division */
+	byte_spot = bit / 8;
+	bitmask = 0x80 >> (bit % 8);
+	if (state)
+		bitmap[byte_spot] |= bitmask;
+	else
+		bitmap[byte_spot] &= ~bitmask;
+}
+
+/**
+ * cipso_v4_cache_entry_free - Frees a cache entry
+ * @entry: the entry to free
+ *
+ * Description:
+ * This function frees the memory associated with a cache entry including the
+ * LSM cache data if there are no longer any users, i.e. reference count == 0.
+ *
+ */
+static void cipso_v4_cache_entry_free(struct cipso_v4_map_cache_entry *entry)
+{
+	if (entry->lsm_data)
+		netlbl_secattr_cache_free(entry->lsm_data);
+	kfree(entry->key);
+	kfree(entry);
+}
+
+/**
+ * cipso_v4_map_cache_hash - Hashing function for the CIPSO cache
+ * @key: the hash key
+ * @key_len: the length of the key in bytes
+ *
+ * Description:
+ * The CIPSO tag hashing function.  Returns a 32-bit hash value.
+ *
+ */
+static u32 cipso_v4_map_cache_hash(const unsigned char *key, u32 key_len)
+{
+	return jhash(key, key_len, 0);
+}
+
+/*
+ * Label Mapping Cache Functions
+ */
+
+/**
+ * cipso_v4_cache_init - Initialize the CIPSO cache
+ *
+ * Description:
+ * Initializes the CIPSO label mapping cache, this function should be called
+ * before any of the other functions defined in this file.  Returns zero on
+ * success, negative values on error.
+ *
+ */
+static int __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.  Returns zero on
+ * success and negative values on failure.
+ *
+ */
+void cipso_v4_cache_invalidate(void)
+{
+	struct cipso_v4_map_cache_entry *entry, *tmp_entry;
+	u32 iter;
+
+	for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {
+		spin_lock_bh(&cipso_v4_cache[iter].lock);
+		list_for_each_entry_safe(entry,
+					 tmp_entry,
+					 &cipso_v4_cache[iter].list, list) {
+			list_del(&entry->list);
+			cipso_v4_cache_entry_free(entry);
+		}
+		cipso_v4_cache[iter].size = 0;
+		spin_unlock_bh(&cipso_v4_cache[iter].lock);
+	}
+}
+
+/**
+ * cipso_v4_cache_check - Check the CIPSO cache for a label mapping
+ * @key: the buffer to check
+ * @key_len: buffer length in bytes
+ * @secattr: the security attribute struct to use
+ *
+ * Description:
+ * This function checks the cache to see if a label mapping already exists for
+ * the given key.  If there is a match then the cache is adjusted and the
+ * @secattr struct is populated with the correct LSM security attributes.  The
+ * cache is adjusted in the following manner if the entry is not already the
+ * first in the cache bucket:
+ *
+ *  1. The cache entry's activity counter is incremented
+ *  2. The previous (higher ranking) entry's activity counter is decremented
+ *  3. If the difference between the two activity counters is geater than
+ *     CIPSO_V4_CACHE_REORDERLIMIT the two entries are swapped
+ *
+ * Returns zero on success, -ENOENT for a cache miss, and other negative values
+ * on error.
+ *
+ */
+static int cipso_v4_cache_check(const unsigned char *key,
+				u32 key_len,
+				struct netlbl_lsm_secattr *secattr)
+{
+	u32 bkt;
+	struct cipso_v4_map_cache_entry *entry;
+	struct cipso_v4_map_cache_entry *prev_entry = NULL;
+	u32 hash;
+
+	if (!cipso_v4_cache_enabled)
+		return -ENOENT;
+
+	hash = cipso_v4_map_cache_hash(key, key_len);
+	bkt = hash & (CIPSO_V4_CACHE_BUCKETS - 1);
+	spin_lock_bh(&cipso_v4_cache[bkt].lock);
+	list_for_each_entry(entry, &cipso_v4_cache[bkt].list, list) {
+		if (entry->hash == hash &&
+		    entry->key_len == key_len &&
+		    memcmp(entry->key, key, key_len) == 0) {
+			entry->activity += 1;
+			atomic_inc(&entry->lsm_data->refcount);
+			secattr->cache = entry->lsm_data;
+			secattr->flags |= NETLBL_SECATTR_CACHE;
+			secattr->type = NETLBL_NLTYPE_CIPSOV4;
+			if (!prev_entry) {
+				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 unsigned char *cipso_ptr,
+		       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;
+	u32 cipso_ptr_len;
+
+	if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 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);
+	atomic_inc(&secattr->cache->refcount);
+	entry->lsm_data = secattr->cache;
+
+	bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
+	spin_lock_bh(&cipso_v4_cache[bkt].lock);
+	if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
+		list_add(&entry->list, &cipso_v4_cache[bkt].list);
+		cipso_v4_cache[bkt].size += 1;
+	} else {
+		old_entry = list_entry(cipso_v4_cache[bkt].list.prev,
+				       struct cipso_v4_map_cache_entry, list);
+		list_del(&old_entry->list);
+		list_add(&entry->list, &cipso_v4_cache[bkt].list);
+		cipso_v4_cache_entry_free(old_entry);
+	}
+	spin_unlock_bh(&cipso_v4_cache[bkt].lock);
+
+	return 0;
+
+cache_add_failure:
+	if (entry)
+		cipso_v4_cache_entry_free(entry);
+	return ret_val;
+}
+
+/*
+ * DOI List Functions
+ */
+
+/**
+ * cipso_v4_doi_search - Searches for a DOI definition
+ * @doi: the DOI to search for
+ *
+ * Description:
+ * Search the DOI definition list for a DOI definition with a DOI value that
+ * matches @doi.  The caller is responsible for calling rcu_read_[un]lock().
+ * Returns a pointer to the DOI definition on success and NULL on failure.
+ */
+static struct cipso_v4_doi *cipso_v4_doi_search(u32 doi)
+{
+	struct cipso_v4_doi *iter;
+
+	list_for_each_entry_rcu(iter, &cipso_v4_doi_list, list)
+		if (iter->doi == doi && atomic_read(&iter->refcount))
+			return iter;
+	return NULL;
+}
+
+/**
+ * cipso_v4_doi_add - Add a new DOI to the CIPSO protocol engine
+ * @doi_def: the DOI structure
+ * @audit_info: NetLabel audit information
+ *
+ * Description:
+ * The caller defines a new DOI for use by the CIPSO engine and calls this
+ * function to add it to the list of acceptable domains.  The caller must
+ * ensure that the mapping table specified in @doi_def->map meets all of the
+ * requirements of the mapping type (see cipso_ipv4.h for details).  Returns
+ * zero on success and non-zero on failure.
+ *
+ */
+int cipso_v4_doi_add(struct cipso_v4_doi *doi_def,
+		     struct netlbl_audit *audit_info)
+{
+	int ret_val = -EINVAL;
+	u32 iter;
+	u32 doi;
+	u32 doi_type;
+	struct audit_buffer *audit_buf;
+
+	doi = doi_def->doi;
+	doi_type = doi_def->type;
+
+	if (doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
+		goto doi_add_return;
+	for (iter = 0; iter < CIPSO_V4_TAG_MAXCNT; iter++) {
+		switch (doi_def->tags[iter]) {
+		case CIPSO_V4_TAG_RBITMAP:
+			break;
+		case CIPSO_V4_TAG_RANGE:
+		case CIPSO_V4_TAG_ENUM:
+			if (doi_def->type != CIPSO_V4_MAP_PASS)
+				goto doi_add_return;
+			break;
+		case CIPSO_V4_TAG_LOCAL:
+			if (doi_def->type != CIPSO_V4_MAP_LOCAL)
+				goto doi_add_return;
+			break;
+		case CIPSO_V4_TAG_INVALID:
+			if (iter == 0)
+				goto doi_add_return;
+			break;
+		default:
+			goto doi_add_return;
+		}
+	}
+
+	atomic_set(&doi_def->refcount, 1);
+
+	spin_lock(&cipso_v4_doi_list_lock);
+	if (cipso_v4_doi_search(doi_def->doi)) {
+		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);
+		break;
+	}
+	kfree(doi_def);
+}
+
+/**
+ * cipso_v4_doi_free_rcu - Frees a DOI definition via the RCU pointer
+ * @entry: the entry's RCU field
+ *
+ * Description:
+ * This function is designed to be used as a callback to the call_rcu()
+ * function so that the memory allocated to the DOI definition can be released
+ * safely.
+ *
+ */
+static void cipso_v4_doi_free_rcu(struct rcu_head *entry)
+{
+	struct cipso_v4_doi *doi_def;
+
+	doi_def = container_of(entry, struct cipso_v4_doi, rcu);
+	cipso_v4_doi_free(doi_def);
+}
+
+/**
+ * cipso_v4_doi_remove - Remove an existing DOI from the CIPSO protocol engine
+ * @doi: the DOI value
+ * @audit_secid: the LSM secid to use in the audit message
+ *
+ * Description:
+ * Removes a DOI definition from the CIPSO engine.  The NetLabel routines will
+ * be called to release their own LSM domain mappings as well as our own
+ * domain list.  Returns zero on success and negative values on failure.
+ *
+ */
+int cipso_v4_doi_remove(u32 doi, struct netlbl_audit *audit_info)
+{
+	int ret_val;
+	struct cipso_v4_doi *doi_def;
+	struct audit_buffer *audit_buf;
+
+	spin_lock(&cipso_v4_doi_list_lock);
+	doi_def = cipso_v4_doi_search(doi);
+	if (!doi_def) {
+		spin_unlock(&cipso_v4_doi_list_lock);
+		ret_val = -ENOENT;
+		goto doi_remove_return;
+	}
+	if (!atomic_dec_and_test(&doi_def->refcount)) {
+		spin_unlock(&cipso_v4_doi_list_lock);
+		ret_val = -EBUSY;
+		goto doi_remove_return;
+	}
+	list_del_rcu(&doi_def->list);
+	spin_unlock(&cipso_v4_doi_list_lock);
+
+	cipso_v4_cache_invalidate();
+	call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);
+	ret_val = 0;
+
+doi_remove_return:
+	audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_DEL, audit_info);
+	if (audit_buf) {
+		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 (!atomic_inc_not_zero(&doi_def->refcount))
+		doi_def = NULL;
+
+doi_getdef_return:
+	rcu_read_unlock();
+	return doi_def;
+}
+
+/**
+ * cipso_v4_doi_putdef - Releases a reference for the given DOI definition
+ * @doi_def: the DOI definition
+ *
+ * Description:
+ * Releases a DOI definition reference obtained from cipso_v4_doi_getdef().
+ *
+ */
+void cipso_v4_doi_putdef(struct cipso_v4_doi *doi_def)
+{
+	if (!doi_def)
+		return;
+
+	if (!atomic_dec_and_test(&doi_def->refcount))
+		return;
+	spin_lock(&cipso_v4_doi_list_lock);
+	list_del_rcu(&doi_def->list);
+	spin_unlock(&cipso_v4_doi_list_lock);
+
+	cipso_v4_cache_invalidate();
+	call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);
+}
+
+/**
+ * cipso_v4_doi_walk - Iterate through the DOI definitions
+ * @skip_cnt: skip past this number of DOI definitions, updated
+ * @callback: callback for each DOI definition
+ * @cb_arg: argument for the callback function
+ *
+ * Description:
+ * Iterate over the DOI definition list, skipping the first @skip_cnt entries.
+ * For each entry call @callback, if @callback returns a negative value stop
+ * 'walking' through the list and return.  Updates the value in @skip_cnt upon
+ * return.  Returns zero on success, negative values on failure.
+ *
+ */
+int cipso_v4_doi_walk(u32 *skip_cnt,
+		     int (*callback) (struct cipso_v4_doi *doi_def, void *arg),
+		     void *cb_arg)
+{
+	int ret_val = -ENOENT;
+	u32 doi_cnt = 0;
+	struct cipso_v4_doi *iter_doi;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(iter_doi, &cipso_v4_doi_list, list)
+		if (atomic_read(&iter_doi->refcount) > 0) {
+			if (doi_cnt++ < *skip_cnt)
+				continue;
+			ret_val = callback(iter_doi, cb_arg);
+			if (ret_val < 0) {
+				doi_cnt--;
+				goto doi_walk_return;
+			}
+		}
+
+doi_walk_return:
+	rcu_read_unlock();
+	*skip_cnt = doi_cnt;
+	return ret_val;
+}
+
+/*
+ * Label Mapping Functions
+ */
+
+/**
+ * cipso_v4_map_lvl_valid - Checks to see if the given level is understood
+ * @doi_def: the DOI definition
+ * @level: the level to check
+ *
+ * Description:
+ * Checks the given level against the given DOI definition and returns a
+ * negative value if the level does not have a valid mapping and a zero value
+ * if the level is defined by the DOI.
+ *
+ */
+static int cipso_v4_map_lvl_valid(const struct cipso_v4_doi *doi_def, u8 level)
+{
+	switch (doi_def->type) {
+	case CIPSO_V4_MAP_PASS:
+		return 0;
+	case CIPSO_V4_MAP_TRANS:
+		if (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL)
+			return 0;
+		break;
+	}
+
+	return -EFAULT;
+}
+
+/**
+ * cipso_v4_map_lvl_hton - Perform a level mapping from the host to the network
+ * @doi_def: the DOI definition
+ * @host_lvl: the host MLS level
+ * @net_lvl: the network/CIPSO MLS level
+ *
+ * Description:
+ * Perform a label mapping to translate a local MLS level to the correct
+ * CIPSO level using the given DOI definition.  Returns zero on success,
+ * negative values otherwise.
+ *
+ */
+static int cipso_v4_map_lvl_hton(const struct cipso_v4_doi *doi_def,
+				 u32 host_lvl,
+				 u32 *net_lvl)
+{
+	switch (doi_def->type) {
+	case CIPSO_V4_MAP_PASS:
+		*net_lvl = host_lvl;
+		return 0;
+	case CIPSO_V4_MAP_TRANS:
+		if (host_lvl < doi_def->map.std->lvl.local_size &&
+		    doi_def->map.std->lvl.local[host_lvl] < CIPSO_V4_INV_LVL) {
+			*net_lvl = doi_def->map.std->lvl.local[host_lvl];
+			return 0;
+		}
+		return -EPERM;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * cipso_v4_map_lvl_ntoh - Perform a level mapping from the network to the host
+ * @doi_def: the DOI definition
+ * @net_lvl: the network/CIPSO MLS level
+ * @host_lvl: the host MLS level
+ *
+ * Description:
+ * Perform a label mapping to translate a CIPSO level to the correct local MLS
+ * level using the given DOI definition.  Returns zero on success, negative
+ * values otherwise.
+ *
+ */
+static int cipso_v4_map_lvl_ntoh(const struct cipso_v4_doi *doi_def,
+				 u32 net_lvl,
+				 u32 *host_lvl)
+{
+	struct cipso_v4_std_map_tbl *map_tbl;
+
+	switch (doi_def->type) {
+	case CIPSO_V4_MAP_PASS:
+		*host_lvl = net_lvl;
+		return 0;
+	case CIPSO_V4_MAP_TRANS:
+		map_tbl = doi_def->map.std;
+		if (net_lvl < map_tbl->lvl.cipso_size &&
+		    map_tbl->lvl.cipso[net_lvl] < CIPSO_V4_INV_LVL) {
+			*host_lvl = doi_def->map.std->lvl.cipso[net_lvl];
+			return 0;
+		}
+		return -EPERM;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * cipso_v4_map_cat_rbm_valid - Checks to see if the category bitmap is valid
+ * @doi_def: the DOI definition
+ * @bitmap: category bitmap
+ * @bitmap_len: bitmap length in bytes
+ *
+ * Description:
+ * Checks the given category bitmap against the given DOI definition and
+ * returns a negative value if any of the categories in the bitmap do not have
+ * a valid mapping and a zero value if all of the categories are valid.
+ *
+ */
+static int cipso_v4_map_cat_rbm_valid(const struct cipso_v4_doi *doi_def,
+				      const unsigned char *bitmap,
+				      u32 bitmap_len)
+{
+	int cat = -1;
+	u32 bitmap_len_bits = bitmap_len * 8;
+	u32 cipso_cat_size;
+	u32 *cipso_array;
+
+	switch (doi_def->type) {
+	case CIPSO_V4_MAP_PASS:
+		return 0;
+	case CIPSO_V4_MAP_TRANS:
+		cipso_cat_size = doi_def->map.std->cat.cipso_size;
+		cipso_array = doi_def->map.std->cat.cipso;
+		for (;;) {
+			cat = cipso_v4_bitmap_walk(bitmap,
+						   bitmap_len_bits,
+						   cat + 1,
+						   1);
+			if (cat < 0)
+				break;
+			if (cat >= cipso_cat_size ||
+			    cipso_array[cat] >= CIPSO_V4_INV_CAT)
+				return -EFAULT;
+		}
+
+		if (cat == -1)
+			return 0;
+		break;
+	}
+
+	return -EFAULT;
+}
+
+/**
+ * cipso_v4_map_cat_rbm_hton - Perform a category mapping from host to network
+ * @doi_def: the DOI definition
+ * @secattr: the security attributes
+ * @net_cat: the zero'd out category bitmap in network/CIPSO format
+ * @net_cat_len: the length of the CIPSO bitmap in bytes
+ *
+ * Description:
+ * Perform a label mapping to translate a local MLS category bitmap to the
+ * correct CIPSO bitmap using the given DOI definition.  Returns the minimum
+ * size in bytes of the network bitmap on success, negative values otherwise.
+ *
+ */
+static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
+				     const struct netlbl_lsm_secattr *secattr,
+				     unsigned char *net_cat,
+				     u32 net_cat_len)
+{
+	int host_spot = -1;
+	u32 net_spot = CIPSO_V4_INV_CAT;
+	u32 net_spot_max = 0;
+	u32 net_clen_bits = net_cat_len * 8;
+	u32 host_cat_size = 0;
+	u32 *host_cat_array = NULL;
+
+	if (doi_def->type == CIPSO_V4_MAP_TRANS) {
+		host_cat_size = doi_def->map.std->cat.local_size;
+		host_cat_array = doi_def->map.std->cat.local;
+	}
+
+	for (;;) {
+		host_spot = netlbl_catmap_walk(secattr->attr.mls.cat,
+					       host_spot + 1);
+		if (host_spot < 0)
+			break;
+
+		switch (doi_def->type) {
+		case CIPSO_V4_MAP_PASS:
+			net_spot = host_spot;
+			break;
+		case CIPSO_V4_MAP_TRANS:
+			if (host_spot >= host_cat_size)
+				return -EPERM;
+			net_spot = host_cat_array[host_spot];
+			if (net_spot >= CIPSO_V4_INV_CAT)
+				return -EPERM;
+			break;
+		}
+		if (net_spot >= net_clen_bits)
+			return -ENOSPC;
+		cipso_v4_bitmap_setbit(net_cat, net_spot, 1);
+
+		if (net_spot > net_spot_max)
+			net_spot_max = net_spot;
+	}
+
+	if (++net_spot_max % 8)
+		return net_spot_max / 8 + 1;
+	return net_spot_max / 8;
+}
+
+/**
+ * cipso_v4_map_cat_rbm_ntoh - Perform a category mapping from network to host
+ * @doi_def: the DOI definition
+ * @net_cat: the category bitmap in network/CIPSO format
+ * @net_cat_len: the length of the CIPSO bitmap in bytes
+ * @secattr: the security attributes
+ *
+ * Description:
+ * Perform a label mapping to translate a CIPSO bitmap to the correct local
+ * MLS category bitmap using the given DOI definition.  Returns zero on
+ * success, negative values on failure.
+ *
+ */
+static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
+				     const unsigned char *net_cat,
+				     u32 net_cat_len,
+				     struct netlbl_lsm_secattr *secattr)
+{
+	int ret_val;
+	int net_spot = -1;
+	u32 host_spot = CIPSO_V4_INV_CAT;
+	u32 net_clen_bits = net_cat_len * 8;
+	u32 net_cat_size = 0;
+	u32 *net_cat_array = NULL;
+
+	if (doi_def->type == CIPSO_V4_MAP_TRANS) {
+		net_cat_size = doi_def->map.std->cat.cipso_size;
+		net_cat_array = doi_def->map.std->cat.cipso;
+	}
+
+	for (;;) {
+		net_spot = cipso_v4_bitmap_walk(net_cat,
+						net_clen_bits,
+						net_spot + 1,
+						1);
+		if (net_spot < 0) {
+			if (net_spot == -2)
+				return -EFAULT;
+			return 0;
+		}
+
+		switch (doi_def->type) {
+		case CIPSO_V4_MAP_PASS:
+			host_spot = net_spot;
+			break;
+		case CIPSO_V4_MAP_TRANS:
+			if (net_spot >= net_cat_size)
+				return -EPERM;
+			host_spot = net_cat_array[net_spot];
+			if (host_spot >= CIPSO_V4_INV_CAT)
+				return -EPERM;
+			break;
+		}
+		ret_val = netlbl_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;
+	*(__be32 *)&buf[2] = htonl(doi_def->doi);
+}
+
+/**
+ * cipso_v4_gentag_rbm - Generate a CIPSO restricted bitmap tag (type #1)
+ * @doi_def: the DOI definition
+ * @secattr: the security attributes
+ * @buffer: the option buffer
+ * @buffer_len: length of buffer in bytes
+ *
+ * Description:
+ * Generate a CIPSO option using the restricted bitmap tag, tag type #1.  The
+ * actual buffer length may be larger than the indicated size due to
+ * translation between host and network category bitmaps.  Returns the size of
+ * the tag on success, negative values on failure.
+ *
+ */
+static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
+			       const struct netlbl_lsm_secattr *secattr,
+			       unsigned char *buffer,
+			       u32 buffer_len)
+{
+	int ret_val;
+	u32 tag_len;
+	u32 level;
+
+	if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
+		return -EPERM;
+
+	ret_val = cipso_v4_map_lvl_hton(doi_def,
+					secattr->attr.mls.lvl,
+					&level);
+	if (ret_val != 0)
+		return ret_val;
+
+	if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
+		ret_val = cipso_v4_map_cat_rbm_hton(doi_def,
+						    secattr,
+						    &buffer[4],
+						    buffer_len - 4);
+		if (ret_val < 0)
+			return ret_val;
+
+		/* This will send packets using the "optimized" format when
+		 * possible as specified in  section 3.4.2.6 of the
+		 * CIPSO draft. */
+		if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)
+			tag_len = 14;
+		else
+			tag_len = 4 + ret_val;
+	} else
+		tag_len = 4;
+
+	buffer[0] = CIPSO_V4_TAG_RBITMAP;
+	buffer[1] = tag_len;
+	buffer[3] = level;
+
+	return tag_len;
+}
+
+/**
+ * cipso_v4_parsetag_rbm - Parse a CIPSO restricted bitmap tag
+ * @doi_def: the DOI definition
+ * @tag: the CIPSO tag
+ * @secattr: the security attributes
+ *
+ * Description:
+ * Parse a CIPSO restricted bitmap tag (tag type #1) and return the security
+ * attributes in @secattr.  Return zero on success, negatives values on
+ * failure.
+ *
+ */
+static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
+				 const unsigned char *tag,
+				 struct netlbl_lsm_secattr *secattr)
+{
+	int ret_val;
+	u8 tag_len = tag[1];
+	u32 level;
+
+	ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
+	if (ret_val != 0)
+		return ret_val;
+	secattr->attr.mls.lvl = level;
+	secattr->flags |= NETLBL_SECATTR_MLS_LVL;
+
+	if (tag_len > 4) {
+		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;
+		}
+
+		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;
+		}
+
+		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 if 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 > 0; ) {
+		if (optptr[0] == IPOPT_CIPSO)
+			return optptr;
+		taglen = optptr[1];
+		optlen -= taglen;
+		optptr += taglen;
+	}
+
+	return NULL;
+}
+
+/**
+ * cipso_v4_validate - Validate a CIPSO option
+ * @option: the start of the option, on error it is set to point to the error
+ *
+ * Description:
+ * This routine is called to validate a CIPSO option, it checks all of the
+ * fields to ensure that they are at least valid, see the draft snippet below
+ * for details.  If the option is valid then a zero value is returned and
+ * the value of @option is unchanged.  If the option is invalid then a
+ * non-zero value is returned and @option is adjusted to point to the
+ * offending portion of the option.  From the IETF draft ...
+ *
+ *  "If any field within the CIPSO options, such as the DOI identifier, is not
+ *   recognized the IP datagram is discarded and an ICMP 'parameter problem'
+ *   (type 12) is generated and returned.  The ICMP code field is set to 'bad
+ *   parameter' (code 0) and the pointer is set to the start of the CIPSO field
+ *   that is unrecognized."
+ *
+ */
+int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
+{
+	unsigned char *opt = *option;
+	unsigned char *tag;
+	unsigned char opt_iter;
+	unsigned char err_offset = 0;
+	u8 opt_len;
+	u8 tag_len;
+	struct cipso_v4_doi *doi_def = NULL;
+	u32 tag_iter;
+
+	/* caller already checks for length values that are too large */
+	opt_len = opt[1];
+	if (opt_len < 8) {
+		err_offset = 1;
+		goto validate_return;
+	}
+
+	rcu_read_lock();
+	doi_def = cipso_v4_doi_search(get_unaligned_be32(&opt[2]));
+	if (!doi_def) {
+		err_offset = 2;
+		goto validate_return_locked;
+	}
+
+	opt_iter = CIPSO_V4_HDR_LEN;
+	tag = opt + opt_iter;
+	while (opt_iter < opt_len) {
+		for (tag_iter = 0; doi_def->tags[tag_iter] != tag[0];)
+			if (doi_def->tags[tag_iter] == CIPSO_V4_TAG_INVALID ||
+			    ++tag_iter == CIPSO_V4_TAG_MAXCNT) {
+				err_offset = opt_iter;
+				goto validate_return_locked;
+			}
+
+		tag_len = tag[1];
+		if (tag_len > (opt_len - opt_iter)) {
+			err_offset = opt_iter + 1;
+			goto validate_return_locked;
+		}
+
+		switch (tag[0]) {
+		case CIPSO_V4_TAG_RBITMAP:
+			if (tag_len < CIPSO_V4_TAG_RBM_BLEN) {
+				err_offset = opt_iter + 1;
+				goto validate_return_locked;
+			}
+
+			/* We are already going to do all the verification
+			 * necessary at the socket layer so from our point of
+			 * view it is safe to turn these checks off (and less
+			 * work), however, the CIPSO draft says we should do
+			 * all the CIPSO validations here but it doesn't
+			 * really specify _exactly_ what we need to validate
+			 * ... so, just make it a sysctl tunable. */
+			if (cipso_v4_rbm_strictvalid) {
+				if (cipso_v4_map_lvl_valid(doi_def,
+							   tag[3]) < 0) {
+					err_offset = opt_iter + 3;
+					goto validate_return_locked;
+				}
+				if (tag_len > CIPSO_V4_TAG_RBM_BLEN &&
+				    cipso_v4_map_cat_rbm_valid(doi_def,
+							    &tag[4],
+							    tag_len - 4) < 0) {
+					err_offset = opt_iter + 4;
+					goto validate_return_locked;
+				}
+			}
+			break;
+		case CIPSO_V4_TAG_ENUM:
+			if (tag_len < CIPSO_V4_TAG_ENUM_BLEN) {
+				err_offset = opt_iter + 1;
+				goto validate_return_locked;
+			}
+
+			if (cipso_v4_map_lvl_valid(doi_def,
+						   tag[3]) < 0) {
+				err_offset = opt_iter + 3;
+				goto validate_return_locked;
+			}
+			if (tag_len > CIPSO_V4_TAG_ENUM_BLEN &&
+			    cipso_v4_map_cat_enum_valid(doi_def,
+							&tag[4],
+							tag_len - 4) < 0) {
+				err_offset = opt_iter + 4;
+				goto validate_return_locked;
+			}
+			break;
+		case CIPSO_V4_TAG_RANGE:
+			if (tag_len < CIPSO_V4_TAG_RNG_BLEN) {
+				err_offset = opt_iter + 1;
+				goto validate_return_locked;
+			}
+
+			if (cipso_v4_map_lvl_valid(doi_def,
+						   tag[3]) < 0) {
+				err_offset = opt_iter + 3;
+				goto validate_return_locked;
+			}
+			if (tag_len > CIPSO_V4_TAG_RNG_BLEN &&
+			    cipso_v4_map_cat_rng_valid(doi_def,
+						       &tag[4],
+						       tag_len - 4) < 0) {
+				err_offset = opt_iter + 4;
+				goto validate_return_locked;
+			}
+			break;
+		case CIPSO_V4_TAG_LOCAL:
+			/* This is a non-standard tag that we only allow for
+			 * local connections, so if the incoming interface is
+			 * not the loopback device drop the packet. 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)
+{
+	if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
+		return;
+
+	if (gateway)
+		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0);
+	else
+		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0);
+}
+
+/**
+ * cipso_v4_genopt - Generate a CIPSO option
+ * @buf: the option buffer
+ * @buf_len: the size of opt_buf
+ * @doi_def: the CIPSO DOI to use
+ * @secattr: the security attributes
+ *
+ * Description:
+ * Generate a CIPSO option using the DOI definition and security attributes
+ * passed to the function.  Returns the length of the option on success and
+ * negative values on failure.
+ *
+ */
+static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
+			   const struct cipso_v4_doi *doi_def,
+			   const struct netlbl_lsm_secattr *secattr)
+{
+	int ret_val;
+	u32 iter;
+
+	if (buf_len <= CIPSO_V4_HDR_LEN)
+		return -ENOSPC;
+
+	/* XXX - This code assumes only one tag per CIPSO option which isn't
+	 * really a good assumption to make but since we only support the MAC
+	 * tags right now it is a safe assumption. */
+	iter = 0;
+	do {
+		memset(buf, 0, buf_len);
+		switch (doi_def->tags[iter]) {
+		case CIPSO_V4_TAG_RBITMAP:
+			ret_val = cipso_v4_gentag_rbm(doi_def,
+						   secattr,
+						   &buf[CIPSO_V4_HDR_LEN],
+						   buf_len - CIPSO_V4_HDR_LEN);
+			break;
+		case CIPSO_V4_TAG_ENUM:
+			ret_val = cipso_v4_gentag_enum(doi_def,
+						   secattr,
+						   &buf[CIPSO_V4_HDR_LEN],
+						   buf_len - CIPSO_V4_HDR_LEN);
+			break;
+		case CIPSO_V4_TAG_RANGE:
+			ret_val = cipso_v4_gentag_rng(doi_def,
+						   secattr,
+						   &buf[CIPSO_V4_HDR_LEN],
+						   buf_len - CIPSO_V4_HDR_LEN);
+			break;
+		case CIPSO_V4_TAG_LOCAL:
+			ret_val = cipso_v4_gentag_loc(doi_def,
+						   secattr,
+						   &buf[CIPSO_V4_HDR_LEN],
+						   buf_len - CIPSO_V4_HDR_LEN);
+			break;
+		default:
+			return -EPERM;
+		}
+
+		iter++;
+	} while (ret_val < 0 &&
+		 iter < CIPSO_V4_TAG_MAXCNT &&
+		 doi_def->tags[iter] != CIPSO_V4_TAG_INVALID);
+	if (ret_val < 0)
+		return ret_val;
+	cipso_v4_gentag_hdr(doi_def, buf, ret_val);
+	return CIPSO_V4_HDR_LEN + ret_val;
+}
+
+/**
+ * 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, sock_owned_by_user(sk));
+	if (sk_inet->is_icsk) {
+		sk_conn = inet_csk(sk);
+		if (old)
+			sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
+		sk_conn->icsk_ext_hdr_len += opt->opt.optlen;
+		sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
+	}
+	rcu_assign_pointer(sk_inet->inet_opt, opt);
+	if (old)
+		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(&req_inet->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 **opt_ptr)
+{
+	int hdr_delta = 0;
+	struct ip_options_rcu *opt = *opt_ptr;
+
+	if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) {
+		u8 cipso_len;
+		u8 cipso_off;
+		unsigned char *cipso_ptr;
+		int iter;
+		int optlen_new;
+
+		cipso_off = opt->opt.cipso - sizeof(struct iphdr);
+		cipso_ptr = &opt->opt.__data[cipso_off];
+		cipso_len = cipso_ptr[1];
+
+		if (opt->opt.srr > opt->opt.cipso)
+			opt->opt.srr -= cipso_len;
+		if (opt->opt.rr > opt->opt.cipso)
+			opt->opt.rr -= cipso_len;
+		if (opt->opt.ts > opt->opt.cipso)
+			opt->opt.ts -= cipso_len;
+		if (opt->opt.router_alert > opt->opt.cipso)
+			opt->opt.router_alert -= cipso_len;
+		opt->opt.cipso = 0;
+
+		memmove(cipso_ptr, cipso_ptr + cipso_len,
+			opt->opt.optlen - cipso_off - cipso_len);
+
+		/* determining the new total option length is tricky because of
+		 * the padding necessary, the only thing i can think to do at
+		 * this point is walk the options one-by-one, skipping the
+		 * padding at the end to determine the actual option size and
+		 * from there we can determine the new total option length */
+		iter = 0;
+		optlen_new = 0;
+		while (iter < opt->opt.optlen)
+			if (opt->opt.__data[iter] != IPOPT_NOP) {
+				iter += opt->opt.__data[iter + 1];
+				optlen_new = iter;
+			} else
+				iter++;
+		hdr_delta = opt->opt.optlen;
+		opt->opt.optlen = (optlen_new + 3) & ~3;
+		hdr_delta -= opt->opt.optlen;
+	} else {
+		/* only the cipso option was present on the socket so we can
+		 * remove the entire option struct */
+		*opt_ptr = NULL;
+		hdr_delta = opt->opt.optlen;
+		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)
+{
+	int hdr_delta;
+	struct ip_options_rcu *opt;
+	struct inet_sock *sk_inet;
+
+	sk_inet = inet_sk(sk);
+	opt = rcu_dereference_protected(sk_inet->inet_opt, 1);
+	if (!opt || opt->opt.cipso == 0)
+		return;
+
+	hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);
+	if (sk_inet->is_icsk && hdr_delta > 0) {
+		struct inet_connection_sock *sk_conn = inet_csk(sk);
+		sk_conn->icsk_ext_hdr_len -= hdr_delta;
+		sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
+	}
+}
+
+/**
+ * cipso_v4_req_delattr - Delete the CIPSO option from a request socket
+ * @reg: the request socket
+ *
+ * Description:
+ * Removes the CIPSO option from a request socket, if present.
+ *
+ */
+void cipso_v4_req_delattr(struct request_sock *req)
+{
+	struct ip_options_rcu *opt;
+	struct inet_request_sock *req_inet;
+
+	req_inet = inet_rsk(req);
+	opt = req_inet->opt;
+	if (!opt || opt->opt.cipso == 0)
+		return;
+
+	cipso_v4_delopt(&req_inet->opt);
+}
+
+/**
+ * cipso_v4_getattr - Helper function for the cipso_v4_*_getattr functions
+ * @cipso: the CIPSO v4 option
+ * @secattr: the security attributes
+ *
+ * Description:
+ * Inspect @cipso and return the security attributes in @secattr.  Returns zero
+ * on success and negative values on failure.
+ *
+ */
+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
+ * @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);