/*
 * NetLabel Kernel API
 *
 * This file defines the kernel API for the NetLabel system.  The NetLabel
 * system manages static and dynamic label mappings for network protocols such
 * as CIPSO and RIPSO.
 *
 * Author: Paul Moore <paul@paul-moore.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, 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/slab.h>
#include <linux/audit.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <asm/bug.h>
#include <linux/atomic.h>

#include "netlabel_domainhash.h"
#include "netlabel_unlabeled.h"
#include "netlabel_cipso_v4.h"
#include "netlabel_user.h"
#include "netlabel_mgmt.h"
#include "netlabel_addrlist.h"

/*
 * Configuration Functions
 */

/**
 * netlbl_cfg_map_del - Remove a NetLabel/LSM domain mapping
 * @domain: the domain mapping to remove
 * @family: address family
 * @addr: IP address
 * @mask: IP address mask
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Removes a NetLabel/LSM domain mapping.  A @domain value of NULL causes the
 * default domain mapping to be removed.  Returns zero on success, negative
 * values on failure.
 *
 */
int netlbl_cfg_map_del(const char *domain,
                       u16 family,
                       const void *addr,
                       const void *mask,
                       struct netlbl_audit *audit_info)
{
        if (addr == NULL && mask == NULL) {
                return netlbl_domhsh_remove(domain, audit_info);
        } else if (addr != NULL && mask != NULL) {
                switch (family) {
                case AF_INET:
                        return netlbl_domhsh_remove_af4(domain, addr, mask,
                                                        audit_info);
                default:
                        return -EPFNOSUPPORT;
                }
        } else
                return -EINVAL;
}

/**
 * netlbl_cfg_unlbl_map_add - Add a new unlabeled mapping
 * @domain: the domain mapping to add
 * @family: address family
 * @addr: IP address
 * @mask: IP address mask
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Adds a new unlabeled NetLabel/LSM domain mapping.  A @domain value of NULL
 * causes a new default domain mapping to be added.  Returns zero on success,
 * negative values on failure.
 *
 */
int netlbl_cfg_unlbl_map_add(const char *domain,
                             u16 family,
                             const void *addr,
                             const void *mask,
                             struct netlbl_audit *audit_info)
{
        int ret_val = -ENOMEM;
        struct netlbl_dom_map *entry;
        struct netlbl_domaddr_map *addrmap = NULL;
        struct netlbl_domaddr4_map *map4 = NULL;
        struct netlbl_domaddr6_map *map6 = NULL;

        entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
        if (entry == NULL)
                return -ENOMEM;
        if (domain != NULL) {
                entry->domain = kstrdup(domain, GFP_ATOMIC);
                if (entry->domain == NULL)
                        goto cfg_unlbl_map_add_failure;
        }

        if (addr == NULL && mask == NULL)
                entry->type = NETLBL_NLTYPE_UNLABELED;
        else if (addr != NULL && mask != NULL) {
                addrmap = kzalloc(sizeof(*addrmap), GFP_ATOMIC);
                if (addrmap == NULL)
                        goto cfg_unlbl_map_add_failure;
                INIT_LIST_HEAD(&addrmap->list4);
                INIT_LIST_HEAD(&addrmap->list6);

                switch (family) {
                case AF_INET: {
                        const struct in_addr *addr4 = addr;
                        const struct in_addr *mask4 = mask;
                        map4 = kzalloc(sizeof(*map4), GFP_ATOMIC);
                        if (map4 == NULL)
                                goto cfg_unlbl_map_add_failure;
                        map4->type = NETLBL_NLTYPE_UNLABELED;
                        map4->list.addr = addr4->s_addr & mask4->s_addr;
                        map4->list.mask = mask4->s_addr;
                        map4->list.valid = 1;
                        ret_val = netlbl_af4list_add(&map4->list,
                                                     &addrmap->list4);
                        if (ret_val != 0)
                                goto cfg_unlbl_map_add_failure;
                        break;
                        }
#if IS_ENABLED(CONFIG_IPV6)
                case AF_INET6: {
                        const struct in6_addr *addr6 = addr;
                        const struct in6_addr *mask6 = mask;
                        map6 = kzalloc(sizeof(*map6), GFP_ATOMIC);
                        if (map6 == NULL)
                                goto cfg_unlbl_map_add_failure;
                        map6->type = NETLBL_NLTYPE_UNLABELED;
                        map6->list.addr = *addr6;
                        map6->list.addr.s6_addr32[0] &= mask6->s6_addr32[0];
                        map6->list.addr.s6_addr32[1] &= mask6->s6_addr32[1];
                        map6->list.addr.s6_addr32[2] &= mask6->s6_addr32[2];
                        map6->list.addr.s6_addr32[3] &= mask6->s6_addr32[3];
                        map6->list.mask = *mask6;
                        map6->list.valid = 1;
                        ret_val = netlbl_af6list_add(&map6->list,
                                                     &addrmap->list6);
                        if (ret_val != 0)
                                goto cfg_unlbl_map_add_failure;
                        break;
                        }
#endif /* IPv6 */
                default:
                        goto cfg_unlbl_map_add_failure;
                        break;
                }

                entry->type_def.addrsel = addrmap;
                entry->type = NETLBL_NLTYPE_ADDRSELECT;
        } else {
                ret_val = -EINVAL;
                goto cfg_unlbl_map_add_failure;
        }

        ret_val = netlbl_domhsh_add(entry, audit_info);
        if (ret_val != 0)
                goto cfg_unlbl_map_add_failure;

        return 0;

cfg_unlbl_map_add_failure:
        kfree(entry->domain);
        kfree(entry);
        kfree(addrmap);
        kfree(map4);
        kfree(map6);
        return ret_val;
}


/**
 * netlbl_cfg_unlbl_static_add - Adds a new static label
 * @net: network namespace
 * @dev_name: interface name
 * @addr: IP address in network byte order (struct in[6]_addr)
 * @mask: address mask in network byte order (struct in[6]_addr)
 * @family: address family
 * @secid: LSM secid value for the entry
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Adds a new NetLabel static label to be used when protocol provided labels
 * are not present on incoming traffic.  If @dev_name is NULL then the default
 * interface will be used.  Returns zero on success, negative values on failure.
 *
 */
int netlbl_cfg_unlbl_static_add(struct net *net,
                                const char *dev_name,
                                const void *addr,
                                const void *mask,
                                u16 family,
                                u32 secid,
                                struct netlbl_audit *audit_info)
{
        u32 addr_len;

        switch (family) {
        case AF_INET:
                addr_len = sizeof(struct in_addr);
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                addr_len = sizeof(struct in6_addr);
                break;
#endif /* IPv6 */
        default:
                return -EPFNOSUPPORT;
        }

        return netlbl_unlhsh_add(net,
                                 dev_name, addr, mask, addr_len,
                                 secid, audit_info);
}

/**
 * netlbl_cfg_unlbl_static_del - Removes an existing static label
 * @net: network namespace
 * @dev_name: interface name
 * @addr: IP address in network byte order (struct in[6]_addr)
 * @mask: address mask in network byte order (struct in[6]_addr)
 * @family: address family
 * @secid: LSM secid value for the entry
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Removes an existing NetLabel static label used when protocol provided labels
 * are not present on incoming traffic.  If @dev_name is NULL then the default
 * interface will be used.  Returns zero on success, negative values on failure.
 *
 */
int netlbl_cfg_unlbl_static_del(struct net *net,
                                const char *dev_name,
                                const void *addr,
                                const void *mask,
                                u16 family,
                                struct netlbl_audit *audit_info)
{
        u32 addr_len;

        switch (family) {
        case AF_INET:
                addr_len = sizeof(struct in_addr);
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                addr_len = sizeof(struct in6_addr);
                break;
#endif /* IPv6 */
        default:
                return -EPFNOSUPPORT;
        }

        return netlbl_unlhsh_remove(net,
                                    dev_name, addr, mask, addr_len,
                                    audit_info);
}

/**
 * netlbl_cfg_cipsov4_add - Add a new CIPSOv4 DOI definition
 * @doi_def: CIPSO DOI definition
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Add a new CIPSO DOI definition as defined by @doi_def.  Returns zero on
 * success and negative values on failure.
 *
 */
int netlbl_cfg_cipsov4_add(struct cipso_v4_doi *doi_def,
                           struct netlbl_audit *audit_info)
{
        return cipso_v4_doi_add(doi_def, audit_info);
}

/**
 * netlbl_cfg_cipsov4_del - Remove an existing CIPSOv4 DOI definition
 * @doi: CIPSO DOI
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Remove an existing CIPSO DOI definition matching @doi.  Returns zero on
 * success and negative values on failure.
 *
 */
void netlbl_cfg_cipsov4_del(u32 doi, struct netlbl_audit *audit_info)
{
        cipso_v4_doi_remove(doi, audit_info);
}

/**
 * netlbl_cfg_cipsov4_map_add - Add a new CIPSOv4 DOI mapping
 * @doi: the CIPSO DOI
 * @domain: the domain mapping to add
 * @addr: IP address
 * @mask: IP address mask
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Add a new NetLabel/LSM domain mapping for the given CIPSO DOI to the NetLabel
 * subsystem.  A @domain value of NULL adds a new default domain mapping.
 * Returns zero on success, negative values on failure.
 *
 */
int netlbl_cfg_cipsov4_map_add(u32 doi,
                               const char *domain,
                               const struct in_addr *addr,
                               const struct in_addr *mask,
                               struct netlbl_audit *audit_info)
{
        int ret_val = -ENOMEM;
        struct cipso_v4_doi *doi_def;
        struct netlbl_dom_map *entry;
        struct netlbl_domaddr_map *addrmap = NULL;
        struct netlbl_domaddr4_map *addrinfo = NULL;

        doi_def = cipso_v4_doi_getdef(doi);
        if (doi_def == NULL)
                return -ENOENT;

        entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
        if (entry == NULL)
                goto out_entry;
        if (domain != NULL) {
                entry->domain = kstrdup(domain, GFP_ATOMIC);
                if (entry->domain == NULL)
                        goto out_domain;
        }

        if (addr == NULL && mask == NULL) {
                entry->type_def.cipsov4 = doi_def;
                entry->type = NETLBL_NLTYPE_CIPSOV4;
        } else if (addr != NULL && mask != NULL) {
                addrmap = kzalloc(sizeof(*addrmap), GFP_ATOMIC);
                if (addrmap == NULL)
                        goto out_addrmap;
                INIT_LIST_HEAD(&addrmap->list4);
                INIT_LIST_HEAD(&addrmap->list6);

                addrinfo = kzalloc(sizeof(*addrinfo), GFP_ATOMIC);
                if (addrinfo == NULL)
                        goto out_addrinfo;
                addrinfo->type_def.cipsov4 = doi_def;
                addrinfo->type = NETLBL_NLTYPE_CIPSOV4;
                addrinfo->list.addr = addr->s_addr & mask->s_addr;
                addrinfo->list.mask = mask->s_addr;
                addrinfo->list.valid = 1;
                ret_val = netlbl_af4list_add(&addrinfo->list, &addrmap->list4);
                if (ret_val != 0)
                        goto cfg_cipsov4_map_add_failure;

                entry->type_def.addrsel = addrmap;
                entry->type = NETLBL_NLTYPE_ADDRSELECT;
        } else {
                ret_val = -EINVAL;
                goto out_addrmap;
        }

        ret_val = netlbl_domhsh_add(entry, audit_info);
        if (ret_val != 0)
                goto cfg_cipsov4_map_add_failure;

        return 0;

cfg_cipsov4_map_add_failure:
        kfree(addrinfo);
out_addrinfo:
        kfree(addrmap);
out_addrmap:
        kfree(entry->domain);
out_domain:
        kfree(entry);
out_entry:
        cipso_v4_doi_putdef(doi_def);
        return ret_val;
}

/*
 * Security Attribute Functions
 */

/**
 * netlbl_secattr_catmap_walk - Walk a LSM secattr catmap looking for a bit
 * @catmap: the category bitmap
 * @offset: the offset to start searching at, in bits
 *
 * Description:
 * This function walks a LSM secattr category bitmap starting at @offset and
 * returns the spot of the first set bit or -ENOENT if no bits are set.
 *
 */
int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
                               u32 offset)
{
        struct netlbl_lsm_secattr_catmap *iter = catmap;
        u32 node_idx;
        u32 node_bit;
        NETLBL_CATMAP_MAPTYPE bitmap;

        if (offset > iter->startbit) {
                while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
                        iter = iter->next;
                        if (iter == NULL)
                                return -ENOENT;
                }
                node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
                node_bit = offset - iter->startbit -
                           (NETLBL_CATMAP_MAPSIZE * node_idx);
        } else {
                node_idx = 0;
                node_bit = 0;
        }
        bitmap = iter->bitmap[node_idx] >> node_bit;

        for (;;) {
                if (bitmap != 0) {
                        while ((bitmap & NETLBL_CATMAP_BIT) == 0) {
                                bitmap >>= 1;
                                node_bit++;
                        }
                        return iter->startbit +
                                (NETLBL_CATMAP_MAPSIZE * node_idx) + node_bit;
                }
                if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
                        if (iter->next != NULL) {
                                iter = iter->next;
                                node_idx = 0;
                        } else
                                return -ENOENT;
                }
                bitmap = iter->bitmap[node_idx];
                node_bit = 0;
        }

        return -ENOENT;
}

/**
 * netlbl_secattr_catmap_walk_rng - Find the end of a string of set bits
 * @catmap: the category bitmap
 * @offset: the offset to start searching at, in bits
 *
 * Description:
 * This function walks a LSM secattr category bitmap starting at @offset and
 * returns the spot of the first cleared bit or -ENOENT if the offset is past
 * the end of the bitmap.
 *
 */
int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
                                   u32 offset)
{
        struct netlbl_lsm_secattr_catmap *iter = catmap;
        u32 node_idx;
        u32 node_bit;
        NETLBL_CATMAP_MAPTYPE bitmask;
        NETLBL_CATMAP_MAPTYPE bitmap;

        if (offset > iter->startbit) {
                while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
                        iter = iter->next;
                        if (iter == NULL)
                                return -ENOENT;
                }
                node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
                node_bit = offset - iter->startbit -
                           (NETLBL_CATMAP_MAPSIZE * node_idx);
        } else {
                node_idx = 0;
                node_bit = 0;
        }
        bitmask = NETLBL_CATMAP_BIT << node_bit;

        for (;;) {
                bitmap = iter->bitmap[node_idx];
                while (bitmask != 0 && (bitmap & bitmask) != 0) {
                        bitmask <<= 1;
                        node_bit++;
                }

                if (bitmask != 0)
                        return iter->startbit +
                                (NETLBL_CATMAP_MAPSIZE * node_idx) +
                                node_bit - 1;
                else if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
                        if (iter->next == NULL)
                                return iter->startbit + NETLBL_CATMAP_SIZE - 1;
                        iter = iter->next;
                        node_idx = 0;
                }
                bitmask = NETLBL_CATMAP_BIT;
                node_bit = 0;
        }

        return -ENOENT;
}

/**
 * netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
 * @catmap: the category bitmap
 * @bit: the bit to set
 * @flags: memory allocation flags
 *
 * Description:
 * Set the bit specified by @bit in @catmap.  Returns zero on success,
 * negative values on failure.
 *
 */
int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
                                 u32 bit,
                                 gfp_t flags)
{
        struct netlbl_lsm_secattr_catmap *iter = catmap;
        u32 node_bit;
        u32 node_idx;

        while (iter->next != NULL &&
               bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
                iter = iter->next;
        if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
                iter->next = netlbl_secattr_catmap_alloc(flags);
                if (iter->next == NULL)
                        return -ENOMEM;
                iter = iter->next;
                iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
        }

        /* gcc always rounds to zero when doing integer division */
        node_idx = (bit - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
        node_bit = bit - iter->startbit - (NETLBL_CATMAP_MAPSIZE * node_idx);
        iter->bitmap[node_idx] |= NETLBL_CATMAP_BIT << node_bit;

        return 0;
}

/**
 * netlbl_secattr_catmap_setrng - Set a range of bits in a LSM secattr catmap
 * @catmap: the category bitmap
 * @start: the starting bit
 * @end: the last bit in the string
 * @flags: memory allocation flags
 *
 * Description:
 * Set a range of bits, starting at @start and ending with @end.  Returns zero
 * on success, negative values on failure.
 *
 */
int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
                                 u32 start,
                                 u32 end,
                                 gfp_t flags)
{
        int ret_val = 0;
        struct netlbl_lsm_secattr_catmap *iter = catmap;
        u32 iter_max_spot;
        u32 spot;

        /* XXX - This could probably be made a bit faster by combining writes
         * to the catmap instead of setting a single bit each time, but for
         * right now skipping to the start of the range in the catmap should
         * be a nice improvement over calling the individual setbit function
         * repeatedly from a loop. */

        while (iter->next != NULL &&
               start >= (iter->startbit + NETLBL_CATMAP_SIZE))
                iter = iter->next;
        iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;

        for (spot = start; spot <= end && ret_val == 0; spot++) {
                if (spot >= iter_max_spot && iter->next != NULL) {
                        iter = iter->next;
                        iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
                }
                ret_val = netlbl_secattr_catmap_setbit(iter, spot, GFP_ATOMIC);
        }

        return ret_val;
}

/*
 * LSM Functions
 */

/**
 * netlbl_enabled - Determine if the NetLabel subsystem is enabled
 *
 * Description:
 * The LSM can use this function to determine if it should use NetLabel
 * security attributes in it's enforcement mechanism.  Currently, NetLabel is
 * considered to be enabled when it's configuration contains a valid setup for
 * at least one labeled protocol (i.e. NetLabel can understand incoming
 * labeled packets of at least one type); otherwise NetLabel is considered to
 * be disabled.
 *
 */
int netlbl_enabled(void)
{
        /* At some point we probably want to expose this mechanism to the user
         * as well so that admins can toggle NetLabel regardless of the
         * configuration */
        return (atomic_read(&netlabel_mgmt_protocount) > 0);
}

/**
 * netlbl_sock_setattr - Label a socket using the correct protocol
 * @sk: the socket to label
 * @family: protocol family
 * @secattr: the security attributes
 *
 * Description:
 * Attach the correct label to the given socket using the security attributes
 * specified in @secattr.  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, -EDESTADDRREQ if the domain is configured to use
 * network address selectors (can't blindly label the socket), and negative
 * values on all other failures.
 *
 */
int netlbl_sock_setattr(struct sock *sk,
                        u16 family,
                        const struct netlbl_lsm_secattr *secattr)
{
        int ret_val;
        struct netlbl_dom_map *dom_entry;

        rcu_read_lock();
        dom_entry = netlbl_domhsh_getentry(secattr->domain);
        if (dom_entry == NULL) {
                ret_val = -ENOENT;
                goto socket_setattr_return;
        }
        switch (family) {
        case AF_INET:
                switch (dom_entry->type) {
                case NETLBL_NLTYPE_ADDRSELECT:
                        ret_val = -EDESTADDRREQ;
                        break;
                case NETLBL_NLTYPE_CIPSOV4:
                        ret_val = cipso_v4_sock_setattr(sk,
                                                    dom_entry->type_def.cipsov4,
                                                    secattr);
                        break;
                case NETLBL_NLTYPE_UNLABELED:
                        ret_val = 0;
                        break;
                default:
                        ret_val = -ENOENT;
                }
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                /* since we don't support any IPv6 labeling protocols right
                 * now we can optimize everything away until we do */
                ret_val = 0;
                break;
#endif /* IPv6 */
        default:
                ret_val = -EPROTONOSUPPORT;
        }

socket_setattr_return:
        rcu_read_unlock();
        return ret_val;
}

/**
 * netlbl_sock_delattr - Delete all the NetLabel labels on a socket
 * @sk: the socket
 *
 * Description:
 * Remove all the NetLabel labeling from @sk.  The caller is responsible for
 * ensuring that @sk is locked.
 *
 */
void netlbl_sock_delattr(struct sock *sk)
{
        cipso_v4_sock_delattr(sk);
}

/**
 * netlbl_sock_getattr - Determine the security attributes of a sock
 * @sk: the sock
 * @secattr: the security attributes
 *
 * Description:
 * Examines the given sock to see if any NetLabel style labeling has been
 * applied to the sock, if so it parses the socket label and returns the
 * security attributes in @secattr.  Returns zero on success, negative values
 * on failure.
 *
 */
int netlbl_sock_getattr(struct sock *sk,
                        struct netlbl_lsm_secattr *secattr)
{
        int ret_val;

        switch (sk->sk_family) {
        case AF_INET:
                ret_val = cipso_v4_sock_getattr(sk, secattr);
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                ret_val = -ENOMSG;
                break;
#endif /* IPv6 */
        default:
                ret_val = -EPROTONOSUPPORT;
        }

        return ret_val;
}

/**
 * netlbl_conn_setattr - Label a connected socket using the correct protocol
 * @sk: the socket to label
 * @addr: the destination address
 * @secattr: the security attributes
 *
 * Description:
 * Attach the correct label to the given connected socket using the security
 * attributes specified in @secattr.  The caller is responsible for ensuring
 * that @sk is locked.  Returns zero on success, negative values on failure.
 *
 */
int netlbl_conn_setattr(struct sock *sk,
                        struct sockaddr *addr,
                        const struct netlbl_lsm_secattr *secattr)
{
        int ret_val;
        struct sockaddr_in *addr4;
        struct netlbl_domaddr4_map *af4_entry;

        rcu_read_lock();
        switch (addr->sa_family) {
        case AF_INET:
                addr4 = (struct sockaddr_in *)addr;
                af4_entry = netlbl_domhsh_getentry_af4(secattr->domain,
                                                       addr4->sin_addr.s_addr);
                if (af4_entry == NULL) {
                        ret_val = -ENOENT;
                        goto conn_setattr_return;
                }
                switch (af4_entry->type) {
                case NETLBL_NLTYPE_CIPSOV4:
                        ret_val = cipso_v4_sock_setattr(sk,
                                                   af4_entry->type_def.cipsov4,
                                                   secattr);
                        break;
                case NETLBL_NLTYPE_UNLABELED:
                        /* just delete the protocols we support for right now
                         * but we could remove other protocols if needed */
                        cipso_v4_sock_delattr(sk);
                        ret_val = 0;
                        break;
                default:
                        ret_val = -ENOENT;
                }
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                /* since we don't support any IPv6 labeling protocols right
                 * now we can optimize everything away until we do */
                ret_val = 0;
                break;
#endif /* IPv6 */
        default:
                ret_val = -EPROTONOSUPPORT;
        }

conn_setattr_return:
        rcu_read_unlock();
        return ret_val;
}

/**
 * netlbl_req_setattr - Label a request socket using the correct protocol
 * @req: the request socket to label
 * @secattr: the security attributes
 *
 * Description:
 * Attach the correct label to the given socket using the security attributes
 * specified in @secattr.  Returns zero on success, negative values on failure.
 *
 */
int netlbl_req_setattr(struct request_sock *req,
                       const struct netlbl_lsm_secattr *secattr)
{
        int ret_val;
        struct netlbl_dom_map *dom_entry;
        struct netlbl_domaddr4_map *af4_entry;
        u32 proto_type;
        struct cipso_v4_doi *proto_cv4;

        rcu_read_lock();
        dom_entry = netlbl_domhsh_getentry(secattr->domain);
        if (dom_entry == NULL) {
                ret_val = -ENOENT;
                goto req_setattr_return;
        }
        switch (req->rsk_ops->family) {
        case AF_INET:
                if (dom_entry->type == NETLBL_NLTYPE_ADDRSELECT) {
                        struct inet_request_sock *req_inet = inet_rsk(req);
                        af4_entry = netlbl_domhsh_getentry_af4(secattr->domain,
                                                            req_inet->rmt_addr);
                        if (af4_entry == NULL) {
                                ret_val = -ENOENT;
                                goto req_setattr_return;
                        }
                        proto_type = af4_entry->type;
                        proto_cv4 = af4_entry->type_def.cipsov4;
                } else {
                        proto_type = dom_entry->type;
                        proto_cv4 = dom_entry->type_def.cipsov4;
                }
                switch (proto_type) {
                case NETLBL_NLTYPE_CIPSOV4:
                        ret_val = cipso_v4_req_setattr(req, proto_cv4, secattr);
                        break;
                case NETLBL_NLTYPE_UNLABELED:
                        /* just delete the protocols we support for right now
                         * but we could remove other protocols if needed */
                        cipso_v4_req_delattr(req);
                        ret_val = 0;
                        break;
                default:
                        ret_val = -ENOENT;
                }
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                /* since we don't support any IPv6 labeling protocols right
                 * now we can optimize everything away until we do */
                ret_val = 0;
                break;
#endif /* IPv6 */
        default:
                ret_val = -EPROTONOSUPPORT;
        }

req_setattr_return:
        rcu_read_unlock();
        return ret_val;
}

/**
* netlbl_req_delattr - Delete all the NetLabel labels on a socket
* @req: the socket
*
* Description:
* Remove all the NetLabel labeling from @req.
*
*/
void netlbl_req_delattr(struct request_sock *req)
{
        cipso_v4_req_delattr(req);
}

/**
 * netlbl_skbuff_setattr - Label a packet using the correct protocol
 * @skb: the packet
 * @family: protocol family
 * @secattr: the security attributes
 *
 * Description:
 * Attach the correct label to the given packet using the security attributes
 * specified in @secattr.  Returns zero on success, negative values on failure.
 *
 */
int netlbl_skbuff_setattr(struct sk_buff *skb,
                          u16 family,
                          const struct netlbl_lsm_secattr *secattr)
{
        int ret_val;
        struct iphdr *hdr4;
        struct netlbl_domaddr4_map *af4_entry;

        rcu_read_lock();
        switch (family) {
        case AF_INET:
                hdr4 = ip_hdr(skb);
                af4_entry = netlbl_domhsh_getentry_af4(secattr->domain,
                                                       hdr4->daddr);
                if (af4_entry == NULL) {
                        ret_val = -ENOENT;
                        goto skbuff_setattr_return;
                }
                switch (af4_entry->type) {
                case NETLBL_NLTYPE_CIPSOV4:
                        ret_val = cipso_v4_skbuff_setattr(skb,
                                                   af4_entry->type_def.cipsov4,
                                                   secattr);
                        break;
                case NETLBL_NLTYPE_UNLABELED:
                        /* just delete the protocols we support for right now
                         * but we could remove other protocols if needed */
                        ret_val = cipso_v4_skbuff_delattr(skb);
                        break;
                default:
                        ret_val = -ENOENT;
                }
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                /* since we don't support any IPv6 labeling protocols right
                 * now we can optimize everything away until we do */
                ret_val = 0;
                break;
#endif /* IPv6 */
        default:
                ret_val = -EPROTONOSUPPORT;
        }

skbuff_setattr_return:
        rcu_read_unlock();
        return ret_val;
}

/**
 * netlbl_skbuff_getattr - Determine the security attributes of a packet
 * @skb: the packet
 * @family: protocol family
 * @secattr: the security attributes
 *
 * Description:
 * Examines the given packet to see if a recognized form of packet labeling
 * is present, if so it parses the packet label and returns the security
 * attributes in @secattr.  Returns zero on success, negative values on
 * failure.
 *
 */
int netlbl_skbuff_getattr(const struct sk_buff *skb,
                          u16 family,
                          struct netlbl_lsm_secattr *secattr)
{
        switch (family) {
        case AF_INET:
                if (CIPSO_V4_OPTEXIST(skb) &&
                    cipso_v4_skbuff_getattr(skb, secattr) == 0)
                        return 0;
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                break;
#endif /* IPv6 */
        }

        return netlbl_unlabel_getattr(skb, family, secattr);
}

/**
 * netlbl_skbuff_err - Handle a LSM error on a sk_buff
 * @skb: the packet
 * @error: the error code
 * @gateway: true if host is acting as a gateway, false otherwise
 *
 * Description:
 * Deal with a LSM problem when handling the packet in @skb, typically this is
 * a permission denied problem (-EACCES).  The correct action is determined
 * according to the packet's labeling protocol.
 *
 */
void netlbl_skbuff_err(struct sk_buff *skb, int error, int gateway)
{
        if (CIPSO_V4_OPTEXIST(skb))
                cipso_v4_error(skb, error, gateway);
}

/**
 * netlbl_cache_invalidate - Invalidate all of the NetLabel protocol caches
 *
 * Description:
 * For all of the NetLabel protocols that support some form of label mapping
 * cache, invalidate the cache.  Returns zero on success, negative values on

 * error.
 *
 */
void netlbl_cache_invalidate(void)
{
        cipso_v4_cache_invalidate();
}

/**
 * netlbl_cache_add - Add an entry to a NetLabel protocol cache
 * @skb: the packet
 * @secattr: the packet's security attributes
 *
 * Description:
 * Add the LSM security attributes for the given packet to the underlying
 * NetLabel protocol's label mapping cache.  Returns zero on success, negative
 * values on error.
 *
 */
int netlbl_cache_add(const struct sk_buff *skb,
                     const struct netlbl_lsm_secattr *secattr)
{
        if ((secattr->flags & NETLBL_SECATTR_CACHE) == 0)
                return -ENOMSG;

        if (CIPSO_V4_OPTEXIST(skb))
                return cipso_v4_cache_add(skb, secattr);

        return -ENOMSG;
}

/*
 * Protocol Engine Functions
 */

/**
 * netlbl_audit_start - Start an audit message
 * @type: audit message type
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Start an audit message using the type specified in @type and fill the audit
 * message with some fields common to all NetLabel audit messages.  This
 * function should only be used by protocol engines, not LSMs.  Returns a
 * pointer to the audit buffer on success, NULL on failure.
 *
 */
struct audit_buffer *netlbl_audit_start(int type,
                                        struct netlbl_audit *audit_info)
{
        return netlbl_audit_start_common(type, audit_info);
}

/*
 * Setup Functions
 */

/**
 * netlbl_init - Initialize NetLabel
 *
 * Description:
 * Perform the required NetLabel initialization before first use.
 *
 */
static int __init netlbl_init(void)
{
        int ret_val;

        printk(KERN_INFO "NetLabel: Initializing\n");
        printk(KERN_INFO "NetLabel:  domain hash size = %u\n",
               (1 << NETLBL_DOMHSH_BITSIZE));
        printk(KERN_INFO "NetLabel:  protocols ="
               " UNLABELED"
               " CIPSOv4"
               "\n");

        ret_val = netlbl_domhsh_init(NETLBL_DOMHSH_BITSIZE);
        if (ret_val != 0)
                goto init_failure;

        ret_val = netlbl_unlabel_init(NETLBL_UNLHSH_BITSIZE);
        if (ret_val != 0)
                goto init_failure;

        ret_val = netlbl_netlink_init();
        if (ret_val != 0)
                goto init_failure;

        ret_val = netlbl_unlabel_defconf();
        if (ret_val != 0)
                goto init_failure;
        printk(KERN_INFO "NetLabel:  unlabeled traffic allowed by default\n");

        return 0;

init_failure:
        panic("NetLabel: failed to initialize properly (%d)\n", ret_val);
}

subsys_initcall(netlbl_init);