cipso_ipv4.c

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/*
 * 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 <[email protected]>
 *
 */

/*
 * (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008
 *
 * This program is free software;  you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY;  without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program;  if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/jhash.h>
#include <linux/audit.h>
#include <linux/slab.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <linux/atomic.h>
#include <asm/bug.h>
#include <asm/unaligned.h>

/* List of available DOI definitions */
/* XXX - This currently assumes a minimal number of different DOIs in use,
 * if in practice there are a lot of different DOIs this list should
 * probably be turned into a hash table or something similar so we
 * can do quick lookups. */
static DEFINE_SPINLOCK(cipso_v4_doi_list_lock);
static LIST_HEAD(cipso_v4_doi_list);

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

    struct netlbl_lsm_cache *lsm_data;

    u32 activity;
    struct list_head list;
};
static struct cipso_v4_map_cache_bkt *cipso_v4_cache = NULL;

/* Restricted bitmap (tag #1) flags */
int cipso_v4_rbm_optfmt = 0;
int cipso_v4_rbm_strictvalid = 1;

/*
 * Protocol Constants
 */

/* Maximum size of the CIPSO IP option, derived from the fact that the maximum
 * IPv4 header size is 60 bytes and the base IPv4 header is 20 bytes long. */
#define CIPSO_V4_OPT_LEN_MAX          40

/* Length of the base CIPSO option, this includes the option type (1 byte), the
 * option length (1 byte), and the DOI (4 bytes). */
#define CIPSO_V4_HDR_LEN              6

/* Base length of the restrictive category bitmap tag (tag #1). */
#define CIPSO_V4_TAG_RBM_BLEN         4

/* Base length of the enumerated category tag (tag #2). */
#define CIPSO_V4_TAG_ENUM_BLEN        4

/* Base length of the ranged categories bitmap tag (tag #5). */
#define CIPSO_V4_TAG_RNG_BLEN         4
/* The maximum number of category ranges permitted in the ranged category tag
 * (tag #5).  You may note that the IETF draft states that the maximum number
 * of category ranges is 7, but if the low end of the last category range is
 * zero then it is possible to fit 8 category ranges because the zero should
 * be omitted. */
#define CIPSO_V4_TAG_RNG_CAT_MAX      8

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

/*
 * Helper Functions
 */

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;
}

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;
}

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);
}

static u32 cipso_v4_map_cache_hash(const unsigned char *key, u32 key_len)
{
    return jhash(key, key_len, 0);
}

/*
 * Label Mapping Cache Functions
 */

static int cipso_v4_cache_init(void)
{
    u32 iter;

    cipso_v4_cache = kcalloc(CIPSO_V4_CACHE_BUCKETS,
                 sizeof(struct cipso_v4_map_cache_bkt),
                 GFP_KERNEL);
    if (cipso_v4_cache == NULL)
        return -ENOMEM;

    for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {
        spin_lock_init(&cipso_v4_cache[iter].lock);
        cipso_v4_cache[iter].size = 0;
        INIT_LIST_HEAD(&cipso_v4_cache[iter].list);
    }

    return 0;
}

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);
    }
}

static int cipso_v4_cache_check(const unsigned char *key,
                u32 key_len,
                struct netlbl_lsm_secattr *secattr)
{
    u32 bkt;
    struct cipso_v4_map_cache_entry *entry;
    struct cipso_v4_map_cache_entry *prev_entry = NULL;
    u32 hash;

    if (!cipso_v4_cache_enabled)
        return -ENOENT;

    hash = cipso_v4_map_cache_hash(key, key_len);
    bkt = hash & (CIPSO_V4_CACHE_BUCKETS - 1);
    spin_lock_bh(&cipso_v4_cache[bkt].lock);
    list_for_each_entry(entry, &cipso_v4_cache[bkt].list, list) {
        if (entry->hash == hash &&
            entry->key_len == key_len &&
            memcmp(entry->key, key, key_len) == 0) {
            entry->activity += 1;
            atomic_inc(&entry->lsm_data->refcount);
            secattr->cache = entry->lsm_data;
            secattr->flags |= NETLBL_SECATTR_CACHE;
            secattr->type = NETLBL_NLTYPE_CIPSOV4;
            if (prev_entry == NULL) {
                spin_unlock_bh(&cipso_v4_cache[bkt].lock);
                return 0;
            }

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

            spin_unlock_bh(&cipso_v4_cache[bkt].lock);
            return 0;
        }
        prev_entry = entry;
    }
    spin_unlock_bh(&cipso_v4_cache[bkt].lock);

    return -ENOENT;
}

int cipso_v4_cache_add(const struct sk_buff *skb,
               const struct netlbl_lsm_secattr *secattr)
{
    int ret_val = -EPERM;
    u32 bkt;
    struct cipso_v4_map_cache_entry *entry = NULL;
    struct cipso_v4_map_cache_entry *old_entry = NULL;
    unsigned char *cipso_ptr;
    u32 cipso_ptr_len;

    if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 0)
        return 0;

    cipso_ptr = CIPSO_V4_OPTPTR(skb);
    cipso_ptr_len = cipso_ptr[1];

    entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
    if (entry == NULL)
        return -ENOMEM;
    entry->key = kmemdup(cipso_ptr, cipso_ptr_len, GFP_ATOMIC);
    if (entry->key == NULL) {
        ret_val = -ENOMEM;
        goto cache_add_failure;
    }
    entry->key_len = cipso_ptr_len;
    entry->hash = cipso_v4_map_cache_hash(cipso_ptr, cipso_ptr_len);
    atomic_inc(&secattr->cache->refcount);
    entry->lsm_data = secattr->cache;

    bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
    spin_lock_bh(&cipso_v4_cache[bkt].lock);
    if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
        list_add(&entry->list, &cipso_v4_cache[bkt].list);
        cipso_v4_cache[bkt].size += 1;
    } else {
        old_entry = list_entry(cipso_v4_cache[bkt].list.prev,
                       struct cipso_v4_map_cache_entry, list);
        list_del(&old_entry->list);
        list_add(&entry->list, &cipso_v4_cache[bkt].list);
        cipso_v4_cache_entry_free(old_entry);
    }
    spin_unlock_bh(&cipso_v4_cache[bkt].lock);

    return 0;

cache_add_failure:
    if (entry)
        cipso_v4_cache_entry_free(entry);
    return ret_val;
}

/*
 * DOI List Functions
 */

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;
}

int cipso_v4_doi_add(struct cipso_v4_doi *doi_def,
             struct netlbl_audit *audit_info)
{
    int ret_val = -EINVAL;
    u32 iter;
    u32 doi;
    u32 doi_type;
    struct audit_buffer *audit_buf;

    doi = doi_def->doi;
    doi_type = doi_def->type;

    if (doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
        goto doi_add_return;
    for (iter = 0; iter < CIPSO_V4_TAG_MAXCNT; iter++) {
        switch (doi_def->tags[iter]) {
        case CIPSO_V4_TAG_RBITMAP:
            break;
        case CIPSO_V4_TAG_RANGE:
        case CIPSO_V4_TAG_ENUM:
            if (doi_def->type != CIPSO_V4_MAP_PASS)
                goto doi_add_return;
            break;
        case CIPSO_V4_TAG_LOCAL:
            if (doi_def->type != CIPSO_V4_MAP_LOCAL)
                goto doi_add_return;
            break;
        case CIPSO_V4_TAG_INVALID:
            if (iter == 0)
                goto doi_add_return;
            break;
        default:
            goto doi_add_return;
        }
    }

    atomic_set(&doi_def->refcount, 1);

    spin_lock(&cipso_v4_doi_list_lock);
    if (cipso_v4_doi_search(doi_def->doi) != NULL) {
        spin_unlock(&cipso_v4_doi_list_lock);
        ret_val = -EEXIST;
        goto doi_add_return;
    }
    list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
    spin_unlock(&cipso_v4_doi_list_lock);
    ret_val = 0;

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

    return ret_val;
}

void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
{
    if (doi_def == NULL)
        return;

    switch (doi_def->type) {
    case CIPSO_V4_MAP_TRANS:
        kfree(doi_def->map.std->lvl.cipso);
        kfree(doi_def->map.std->lvl.local);
        kfree(doi_def->map.std->cat.cipso);
        kfree(doi_def->map.std->cat.local);
        break;
    }
    kfree(doi_def);
}

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);
}

int cipso_v4_doi_remove(u32 doi, struct netlbl_audit *audit_info)
{
    int ret_val;
    struct cipso_v4_doi *doi_def;
    struct audit_buffer *audit_buf;

    spin_lock(&cipso_v4_doi_list_lock);
    doi_def = cipso_v4_doi_search(doi);
    if (doi_def == NULL) {
        spin_unlock(&cipso_v4_doi_list_lock);
        ret_val = -ENOENT;
        goto doi_remove_return;
    }
    if (!atomic_dec_and_test(&doi_def->refcount)) {
        spin_unlock(&cipso_v4_doi_list_lock);
        ret_val = -EBUSY;
        goto doi_remove_return;
    }
    list_del_rcu(&doi_def->list);
    spin_unlock(&cipso_v4_doi_list_lock);

    cipso_v4_cache_invalidate();
    call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);
    ret_val = 0;

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

    return ret_val;
}

struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi)
{
    struct cipso_v4_doi *doi_def;

    rcu_read_lock();
    doi_def = cipso_v4_doi_search(doi);
    if (doi_def == NULL)
        goto doi_getdef_return;
    if (!atomic_inc_not_zero(&doi_def->refcount))
        doi_def = NULL;

doi_getdef_return:
    rcu_read_unlock();
    return doi_def;
}

void cipso_v4_doi_putdef(struct cipso_v4_doi *doi_def)
{
    if (doi_def == NULL)
        return;

    if (!atomic_dec_and_test(&doi_def->refcount))
        return;
    spin_lock(&cipso_v4_doi_list_lock);
    list_del_rcu(&doi_def->list);
    spin_unlock(&cipso_v4_doi_list_lock);

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

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
 */

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;
}

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;
}

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;
}

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;
}

static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
                     const struct netlbl_lsm_secattr *secattr,
                     unsigned char *net_cat,
                     u32 net_cat_len)
{
    int host_spot = -1;
    u32 net_spot = CIPSO_V4_INV_CAT;
    u32 net_spot_max = 0;
    u32 net_clen_bits = net_cat_len * 8;
    u32 host_cat_size = 0;
    u32 *host_cat_array = NULL;

    if (doi_def->type == CIPSO_V4_MAP_TRANS) {
        host_cat_size = doi_def->map.std->cat.local_size;
        host_cat_array = doi_def->map.std->cat.local;
    }

    for (;;) {
        host_spot = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
                               host_spot + 1);
        if (host_spot < 0)
            break;

        switch (doi_def->type) {
        case CIPSO_V4_MAP_PASS:
            net_spot = host_spot;
            break;
        case CIPSO_V4_MAP_TRANS:
            if (host_spot >= host_cat_size)
                return -EPERM;
            net_spot = host_cat_array[host_spot];
            if (net_spot >= CIPSO_V4_INV_CAT)
                return -EPERM;
            break;
        }
        if (net_spot >= net_clen_bits)
            return -ENOSPC;
        cipso_v4_bitmap_setbit(net_cat, net_spot, 1);

        if (net_spot > net_spot_max)
            net_spot_max = net_spot;
    }

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

static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
                     const unsigned char *net_cat,
                     u32 net_cat_len,
                     struct netlbl_lsm_secattr *secattr)
{
    int ret_val;
    int net_spot = -1;
    u32 host_spot = CIPSO_V4_INV_CAT;
    u32 net_clen_bits = net_cat_len * 8;
    u32 net_cat_size = 0;
    u32 *net_cat_array = NULL;

    if (doi_def->type == CIPSO_V4_MAP_TRANS) {
        net_cat_size = doi_def->map.std->cat.cipso_size;
        net_cat_array = doi_def->map.std->cat.cipso;
    }

    for (;;) {
        net_spot = cipso_v4_bitmap_walk(net_cat,
                        net_clen_bits,
                        net_spot + 1,
                        1);
        if (net_spot < 0) {
            if (net_spot == -2)
                return -EFAULT;
            return 0;
        }

        switch (doi_def->type) {
        case CIPSO_V4_MAP_PASS:
            host_spot = net_spot;
            break;
        case CIPSO_V4_MAP_TRANS:
            if (net_spot >= net_cat_size)
                return -EPERM;
            host_spot = net_cat_array[net_spot];
            if (host_spot >= CIPSO_V4_INV_CAT)
                return -EPERM;
            break;
        }
        ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,
                               host_spot,
                               GFP_ATOMIC);
        if (ret_val != 0)
            return ret_val;
    }

    return -EINVAL;
}

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;
}

static int cipso_v4_map_cat_enum_hton(const struct cipso_v4_doi *doi_def,
                      const struct netlbl_lsm_secattr *secattr,
                      unsigned char *net_cat,
                      u32 net_cat_len)
{
    int cat = -1;
    u32 cat_iter = 0;

    for (;;) {
        cat = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
                         cat + 1);
        if (cat < 0)
            break;
        if ((cat_iter + 2) > net_cat_len)
            return -ENOSPC;

        *((__be16 *)&net_cat[cat_iter]) = htons(cat);
        cat_iter += 2;
    }

    return cat_iter;
}

static int cipso_v4_map_cat_enum_ntoh(const struct cipso_v4_doi *doi_def,
                      const unsigned char *net_cat,
                      u32 net_cat_len,
                      struct netlbl_lsm_secattr *secattr)
{
    int ret_val;
    u32 iter;

    for (iter = 0; iter < net_cat_len; iter += 2) {
        ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,
                get_unaligned_be16(&net_cat[iter]),
                GFP_ATOMIC);
        if (ret_val != 0)
            return ret_val;
    }

    return 0;
}

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;
}

static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def,
                     const struct netlbl_lsm_secattr *secattr,
                     unsigned char *net_cat,
                     u32 net_cat_len)
{
    int iter = -1;
    u16 array[CIPSO_V4_TAG_RNG_CAT_MAX * 2];
    u32 array_cnt = 0;
    u32 cat_size = 0;

    /* make sure we don't overflow the 'array[]' variable */
    if (net_cat_len >
        (CIPSO_V4_OPT_LEN_MAX - CIPSO_V4_HDR_LEN - CIPSO_V4_TAG_RNG_BLEN))
        return -ENOSPC;

    for (;;) {
        iter = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
                          iter + 1);
        if (iter < 0)
            break;
        cat_size += (iter == 0 ? 0 : sizeof(u16));
        if (cat_size > net_cat_len)
            return -ENOSPC;
        array[array_cnt++] = iter;

        iter = netlbl_secattr_catmap_walk_rng(secattr->attr.mls.cat,
                              iter);
        if (iter < 0)
            return -EFAULT;
        cat_size += sizeof(u16);
        if (cat_size > net_cat_len)
            return -ENOSPC;
        array[array_cnt++] = iter;
    }

    for (iter = 0; array_cnt > 0;) {
        *((__be16 *)&net_cat[iter]) = htons(array[--array_cnt]);
        iter += 2;
        array_cnt--;
        if (array[array_cnt] != 0) {
            *((__be16 *)&net_cat[iter]) = htons(array[array_cnt]);
            iter += 2;
        }
    }

    return cat_size;
}

static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def,
                     const unsigned char *net_cat,
                     u32 net_cat_len,
                     struct netlbl_lsm_secattr *secattr)
{
    int ret_val;
    u32 net_iter;
    u16 cat_low;
    u16 cat_high;

    for (net_iter = 0; net_iter < net_cat_len; net_iter += 4) {
        cat_high = get_unaligned_be16(&net_cat[net_iter]);
        if ((net_iter + 4) <= net_cat_len)
            cat_low = get_unaligned_be16(&net_cat[net_iter + 2]);
        else
            cat_low = 0;

        ret_val = netlbl_secattr_catmap_setrng(secattr->attr.mls.cat,
                               cat_low,
                               cat_high,
                               GFP_ATOMIC);
        if (ret_val != 0)
            return ret_val;
    }

    return 0;
}

/*
 * Protocol Handling Functions
 */

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);
}

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;
}

static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
                 const unsigned char *tag,
                 struct netlbl_lsm_secattr *secattr)
{
    int ret_val;
    u8 tag_len = tag[1];
    u32 level;

    ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
    if (ret_val != 0)
        return ret_val;
    secattr->attr.mls.lvl = level;
    secattr->flags |= NETLBL_SECATTR_MLS_LVL;

    if (tag_len > 4) {
        secattr->attr.mls.cat =
                               netlbl_secattr_catmap_alloc(GFP_ATOMIC);
        if (secattr->attr.mls.cat == NULL)
            return -ENOMEM;

        ret_val = cipso_v4_map_cat_rbm_ntoh(doi_def,
                            &tag[4],
                            tag_len - 4,
                            secattr);
        if (ret_val != 0) {
            netlbl_secattr_catmap_free(secattr->attr.mls.cat);
            return ret_val;
        }

        secattr->flags |= NETLBL_SECATTR_MLS_CAT;
    }

    return 0;
}

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;
}

static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
                  const unsigned char *tag,
                  struct netlbl_lsm_secattr *secattr)
{
    int ret_val;
    u8 tag_len = tag[1];
    u32 level;

    ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
    if (ret_val != 0)
        return ret_val;
    secattr->attr.mls.lvl = level;
    secattr->flags |= NETLBL_SECATTR_MLS_LVL;

    if (tag_len > 4) {
        secattr->attr.mls.cat =
                           netlbl_secattr_catmap_alloc(GFP_ATOMIC);
        if (secattr->attr.mls.cat == NULL)
            return -ENOMEM;

        ret_val = cipso_v4_map_cat_enum_ntoh(doi_def,
                             &tag[4],
                             tag_len - 4,
                             secattr);
        if (ret_val != 0) {
            netlbl_secattr_catmap_free(secattr->attr.mls.cat);
            return ret_val;
        }

        secattr->flags |= NETLBL_SECATTR_MLS_CAT;
    }

    return 0;
}

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;
}

static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
                 const unsigned char *tag,
                 struct netlbl_lsm_secattr *secattr)
{
    int ret_val;
    u8 tag_len = tag[1];
    u32 level;

    ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
    if (ret_val != 0)
        return ret_val;
    secattr->attr.mls.lvl = level;
    secattr->flags |= NETLBL_SECATTR_MLS_LVL;

    if (tag_len > 4) {
        secattr->attr.mls.cat =
                           netlbl_secattr_catmap_alloc(GFP_ATOMIC);
        if (secattr->attr.mls.cat == NULL)
            return -ENOMEM;

        ret_val = cipso_v4_map_cat_rng_ntoh(doi_def,
                            &tag[4],
                            tag_len - 4,
                            secattr);
        if (ret_val != 0) {
            netlbl_secattr_catmap_free(secattr->attr.mls.cat);
            return ret_val;
        }

        secattr->flags |= NETLBL_SECATTR_MLS_CAT;
    }

    return 0;
}

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;
}

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;
}

int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
{
    unsigned char *opt = *option;
    unsigned char *tag;
    unsigned char opt_iter;
    unsigned char err_offset = 0;
    u8 opt_len;
    u8 tag_len;
    struct cipso_v4_doi *doi_def = NULL;
    u32 tag_iter;

    /* caller already checks for length values that are too large */
    opt_len = opt[1];
    if (opt_len < 8) {
        err_offset = 1;
        goto validate_return;
    }

    rcu_read_lock();
    doi_def = cipso_v4_doi_search(get_unaligned_be32(&opt[2]));
    if (doi_def == NULL) {
        err_offset = 2;
        goto validate_return_locked;
    }

    opt_iter = CIPSO_V4_HDR_LEN;
    tag = opt + opt_iter;
    while (opt_iter < opt_len) {
        for (tag_iter = 0; doi_def->tags[tag_iter] != tag[0];)
            if (doi_def->tags[tag_iter] == CIPSO_V4_TAG_INVALID ||
                ++tag_iter == CIPSO_V4_TAG_MAXCNT) {
                err_offset = opt_iter;
                goto validate_return_locked;
            }

        tag_len = tag[1];
        if (tag_len > (opt_len - opt_iter)) {
            err_offset = opt_iter + 1;
            goto validate_return_locked;
        }

        switch (tag[0]) {
        case CIPSO_V4_TAG_RBITMAP:
            if (tag_len < CIPSO_V4_TAG_RBM_BLEN) {
                err_offset = opt_iter + 1;
                goto validate_return_locked;
            }

            /* We are already going to do all the verification
             * necessary at the socket layer so from our point of
             * view it is safe to turn these checks off (and less
             * work), however, the CIPSO draft says we should do
             * all the CIPSO validations here but it doesn't
             * really specify _exactly_ what we need to validate
             * ... so, just make it a sysctl tunable. */
            if (cipso_v4_rbm_strictvalid) {
                if (cipso_v4_map_lvl_valid(doi_def,
                               tag[3]) < 0) {
                    err_offset = opt_iter + 3;
                    goto validate_return_locked;
                }
                if (tag_len > CIPSO_V4_TAG_RBM_BLEN &&
                    cipso_v4_map_cat_rbm_valid(doi_def,
                                &tag[4],
                                tag_len - 4) < 0) {
                    err_offset = opt_iter + 4;
                    goto validate_return_locked;
                }
            }
            break;
        case CIPSO_V4_TAG_ENUM:
            if (tag_len < CIPSO_V4_TAG_ENUM_BLEN) {
                err_offset = opt_iter + 1;
                goto validate_return_locked;
            }

            if (cipso_v4_map_lvl_valid(doi_def,
                           tag[3]) < 0) {
                err_offset = opt_iter + 3;
                goto validate_return_locked;
            }
            if (tag_len > CIPSO_V4_TAG_ENUM_BLEN &&
                cipso_v4_map_cat_enum_valid(doi_def,
                            &tag[4],
                            tag_len - 4) < 0) {
                err_offset = opt_iter + 4;
                goto validate_return_locked;
            }
            break;
        case CIPSO_V4_TAG_RANGE:
            if (tag_len < CIPSO_V4_TAG_RNG_BLEN) {
                err_offset = opt_iter + 1;
                goto validate_return_locked;
            }

            if (cipso_v4_map_lvl_valid(doi_def,
                           tag[3]) < 0) {
                err_offset = opt_iter + 3;
                goto validate_return_locked;
            }
            if (tag_len > CIPSO_V4_TAG_RNG_BLEN &&
                cipso_v4_map_cat_rng_valid(doi_def,
                               &tag[4],
                               tag_len - 4) < 0) {
                err_offset = opt_iter + 4;
                goto validate_return_locked;
            }
            break;
        case CIPSO_V4_TAG_LOCAL:
            /* This is a non-standard tag that we only allow for
             * local connections, so if the incoming interface is
             * not the loopback device drop the packet. Further,
             * there is no legitimate reason for setting this from
             * userspace so reject it if skb is NULL. */
            if (skb == NULL || !(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;
}

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);
}

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;
}

int cipso_v4_sock_setattr(struct sock *sk,
              const struct cipso_v4_doi *doi_def,
              const struct netlbl_lsm_secattr *secattr)
{
    int ret_val = -EPERM;
    unsigned char *buf = NULL;
    u32 buf_len;
    u32 opt_len;
    struct ip_options_rcu *old, *opt = NULL;
    struct inet_sock *sk_inet;
    struct inet_connection_sock *sk_conn;

    /* In the case of sock_create_lite(), the sock->sk field is not
     * defined yet but it is not a problem as the only users of these
     * "lite" PF_INET sockets are functions which do an accept() call
     * afterwards so we will label the socket as part of the accept(). */
    if (sk == NULL)
        return 0;

    /* We allocate the maximum CIPSO option size here so we are probably
     * being a little wasteful, but it makes our life _much_ easier later
     * on and after all we are only talking about 40 bytes. */
    buf_len = CIPSO_V4_OPT_LEN_MAX;
    buf = kmalloc(buf_len, GFP_ATOMIC);
    if (buf == NULL) {
        ret_val = -ENOMEM;
        goto socket_setattr_failure;
    }

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

    /* We can't use ip_options_get() directly because it makes a call to
     * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
     * we won't always have CAP_NET_RAW even though we _always_ want to
     * set the IPOPT_CIPSO option. */
    opt_len = (buf_len + 3) & ~3;
    opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
    if (opt == NULL) {
        ret_val = -ENOMEM;
        goto socket_setattr_failure;
    }
    memcpy(opt->opt.__data, buf, buf_len);
    opt->opt.optlen = opt_len;
    opt->opt.cipso = sizeof(struct iphdr);
    kfree(buf);
    buf = NULL;

    sk_inet = inet_sk(sk);

    old = rcu_dereference_protected(sk_inet->inet_opt, sock_owned_by_user(sk));
    if (sk_inet->is_icsk) {
        sk_conn = inet_csk(sk);
        if (old)
            sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
        sk_conn->icsk_ext_hdr_len += opt->opt.optlen;
        sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
    }
    rcu_assign_pointer(sk_inet->inet_opt, opt);
    if (old)
        kfree_rcu(old, rcu);

    return 0;

socket_setattr_failure:
    kfree(buf);
    kfree(opt);
    return ret_val;
}

int cipso_v4_req_setattr(struct request_sock *req,
             const struct cipso_v4_doi *doi_def,
             const struct netlbl_lsm_secattr *secattr)
{
    int ret_val = -EPERM;
    unsigned char *buf = NULL;
    u32 buf_len;
    u32 opt_len;
    struct ip_options_rcu *opt = NULL;
    struct inet_request_sock *req_inet;

    /* We allocate the maximum CIPSO option size here so we are probably
     * being a little wasteful, but it makes our life _much_ easier later
     * on and after all we are only talking about 40 bytes. */
    buf_len = CIPSO_V4_OPT_LEN_MAX;
    buf = kmalloc(buf_len, GFP_ATOMIC);
    if (buf == NULL) {
        ret_val = -ENOMEM;
        goto req_setattr_failure;
    }

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

    /* We can't use ip_options_get() directly because it makes a call to
     * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
     * we won't always have CAP_NET_RAW even though we _always_ want to
     * set the IPOPT_CIPSO option. */
    opt_len = (buf_len + 3) & ~3;
    opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
    if (opt == NULL) {
        ret_val = -ENOMEM;
        goto req_setattr_failure;
    }
    memcpy(opt->opt.__data, buf, buf_len);
    opt->opt.optlen = opt_len;
    opt->opt.cipso = sizeof(struct iphdr);
    kfree(buf);
    buf = NULL;

    req_inet = inet_rsk(req);
    opt = xchg(&req_inet->opt, opt);
    if (opt)
        kfree_rcu(opt, rcu);

    return 0;

req_setattr_failure:
    kfree(buf);
    kfree(opt);
    return ret_val;
}

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;
}

void cipso_v4_sock_delattr(struct sock *sk)
{
    int hdr_delta;
    struct ip_options_rcu *opt;
    struct inet_sock *sk_inet;

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

    hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);
    if (sk_inet->is_icsk && hdr_delta > 0) {
        struct inet_connection_sock *sk_conn = inet_csk(sk);
        sk_conn->icsk_ext_hdr_len -= hdr_delta;
        sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
    }
}

void cipso_v4_req_delattr(struct request_sock *req)
{
    struct ip_options_rcu *opt;
    struct inet_request_sock *req_inet;

    req_inet = inet_rsk(req);
    opt = req_inet->opt;
    if (opt == NULL || opt->opt.cipso == 0)
        return;

    cipso_v4_delopt(&req_inet->opt);
}

static int cipso_v4_getattr(const unsigned char *cipso,
                struct netlbl_lsm_secattr *secattr)
{
    int ret_val = -ENOMSG;
    u32 doi;
    struct cipso_v4_doi *doi_def;

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

    doi = get_unaligned_be32(&cipso[2]);
    rcu_read_lock();
    doi_def = cipso_v4_doi_search(doi);
    if (doi_def == NULL)
        goto getattr_return;
    /* XXX - This code assumes only one tag per CIPSO option which isn't
     * really a good assumption to make but since we only support the MAC
     * tags right now it is a safe assumption. */
    switch (cipso[6]) {
    case CIPSO_V4_TAG_RBITMAP:
        ret_val = cipso_v4_parsetag_rbm(doi_def, &cipso[6], secattr);
        break;
    case CIPSO_V4_TAG_ENUM:
        ret_val = cipso_v4_parsetag_enum(doi_def, &cipso[6], secattr);
        break;
    case CIPSO_V4_TAG_RANGE:
        ret_val = cipso_v4_parsetag_rng(doi_def, &cipso[6], secattr);
        break;
    case CIPSO_V4_TAG_LOCAL:
        ret_val = cipso_v4_parsetag_loc(doi_def, &cipso[6], secattr);
        break;
    }
    if (ret_val == 0)
        secattr->type = NETLBL_NLTYPE_CIPSOV4;

getattr_return:
    rcu_read_unlock();
    return ret_val;
}

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;
}

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;
}

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;
}

int cipso_v4_skbuff_getattr(const struct sk_buff *skb,
                struct netlbl_lsm_secattr *secattr)
{
    return cipso_v4_getattr(CIPSO_V4_OPTPTR(skb), secattr);
}

/*
 * Setup Functions
 */

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);