netlabel_domainhash.c

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/*
 * NetLabel Domain Hash Table
 *
 * This file manages the domain hash table that NetLabel uses to determine
 * which network labeling protocol to use for a given domain.  The NetLabel
 * system manages static and dynamic label mappings for network protocols such
 * as CIPSO and RIPSO.
 *
 * 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/types.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/audit.h>
#include <linux/slab.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <asm/bug.h>

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

struct netlbl_domhsh_tbl {
    struct list_head *tbl;
    u32 size;
};

/* Domain hash table */
/* updates should be so rare that having one spinlock for the entire hash table
 * should be okay */
static DEFINE_SPINLOCK(netlbl_domhsh_lock);
#define netlbl_domhsh_rcu_deref(p) \
    rcu_dereference_check(p, lockdep_is_held(&netlbl_domhsh_lock))
static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
static struct netlbl_dom_map *netlbl_domhsh_def = NULL;

/*
 * Domain Hash Table Helper Functions
 */

static void netlbl_domhsh_free_entry(struct rcu_head *entry)
{
    struct netlbl_dom_map *ptr;
    struct netlbl_af4list *iter4;
    struct netlbl_af4list *tmp4;
#if IS_ENABLED(CONFIG_IPV6)
    struct netlbl_af6list *iter6;
    struct netlbl_af6list *tmp6;
#endif /* IPv6 */

    ptr = container_of(entry, struct netlbl_dom_map, rcu);
    if (ptr->type == NETLBL_NLTYPE_ADDRSELECT) {
        netlbl_af4list_foreach_safe(iter4, tmp4,
                        &ptr->type_def.addrsel->list4) {
            netlbl_af4list_remove_entry(iter4);
            kfree(netlbl_domhsh_addr4_entry(iter4));
        }
#if IS_ENABLED(CONFIG_IPV6)
        netlbl_af6list_foreach_safe(iter6, tmp6,
                        &ptr->type_def.addrsel->list6) {
            netlbl_af6list_remove_entry(iter6);
            kfree(netlbl_domhsh_addr6_entry(iter6));
        }
#endif /* IPv6 */
    }
    kfree(ptr->domain);
    kfree(ptr);
}

static u32 netlbl_domhsh_hash(const char *key)
{
    u32 iter;
    u32 val;
    u32 len;

    /* This is taken (with slight modification) from
     * security/selinux/ss/symtab.c:symhash() */

    for (iter = 0, val = 0, len = strlen(key); iter < len; iter++)
        val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter];
    return val & (netlbl_domhsh_rcu_deref(netlbl_domhsh)->size - 1);
}

static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain)
{
    u32 bkt;
    struct list_head *bkt_list;
    struct netlbl_dom_map *iter;

    if (domain != NULL) {
        bkt = netlbl_domhsh_hash(domain);
        bkt_list = &netlbl_domhsh_rcu_deref(netlbl_domhsh)->tbl[bkt];
        list_for_each_entry_rcu(iter, bkt_list, list)
            if (iter->valid && strcmp(iter->domain, domain) == 0)
                return iter;
    }

    return NULL;
}

static struct netlbl_dom_map *netlbl_domhsh_search_def(const char *domain)
{
    struct netlbl_dom_map *entry;

    entry = netlbl_domhsh_search(domain);
    if (entry == NULL) {
        entry = netlbl_domhsh_rcu_deref(netlbl_domhsh_def);
        if (entry != NULL && !entry->valid)
            entry = NULL;
    }

    return entry;
}

static void netlbl_domhsh_audit_add(struct netlbl_dom_map *entry,
                    struct netlbl_af4list *addr4,
                    struct netlbl_af6list *addr6,
                    int result,
                    struct netlbl_audit *audit_info)
{
    struct audit_buffer *audit_buf;
    struct cipso_v4_doi *cipsov4 = NULL;
    u32 type;

    audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD, audit_info);
    if (audit_buf != NULL) {
        audit_log_format(audit_buf, " nlbl_domain=%s",
                 entry->domain ? entry->domain : "(default)");
        if (addr4 != NULL) {
            struct netlbl_domaddr4_map *map4;
            map4 = netlbl_domhsh_addr4_entry(addr4);
            type = map4->type;
            cipsov4 = map4->type_def.cipsov4;
            netlbl_af4list_audit_addr(audit_buf, 0, NULL,
                          addr4->addr, addr4->mask);
#if IS_ENABLED(CONFIG_IPV6)
        } else if (addr6 != NULL) {
            struct netlbl_domaddr6_map *map6;
            map6 = netlbl_domhsh_addr6_entry(addr6);
            type = map6->type;
            netlbl_af6list_audit_addr(audit_buf, 0, NULL,
                          &addr6->addr, &addr6->mask);
#endif /* IPv6 */
        } else {
            type = entry->type;
            cipsov4 = entry->type_def.cipsov4;
        }
        switch (type) {
        case NETLBL_NLTYPE_UNLABELED:
            audit_log_format(audit_buf, " nlbl_protocol=unlbl");
            break;
        case NETLBL_NLTYPE_CIPSOV4:
            BUG_ON(cipsov4 == NULL);
            audit_log_format(audit_buf,
                     " nlbl_protocol=cipsov4 cipso_doi=%u",
                     cipsov4->doi);
            break;
        }
        audit_log_format(audit_buf, " res=%u", result == 0 ? 1 : 0);
        audit_log_end(audit_buf);
    }
}

/*
 * Domain Hash Table Functions
 */

int __init netlbl_domhsh_init(u32 size)
{
    u32 iter;
    struct netlbl_domhsh_tbl *hsh_tbl;

    if (size == 0)
        return -EINVAL;

    hsh_tbl = kmalloc(sizeof(*hsh_tbl), GFP_KERNEL);
    if (hsh_tbl == NULL)
        return -ENOMEM;
    hsh_tbl->size = 1 << size;
    hsh_tbl->tbl = kcalloc(hsh_tbl->size,
                   sizeof(struct list_head),
                   GFP_KERNEL);
    if (hsh_tbl->tbl == NULL) {
        kfree(hsh_tbl);
        return -ENOMEM;
    }
    for (iter = 0; iter < hsh_tbl->size; iter++)
        INIT_LIST_HEAD(&hsh_tbl->tbl[iter]);

    spin_lock(&netlbl_domhsh_lock);
    rcu_assign_pointer(netlbl_domhsh, hsh_tbl);
    spin_unlock(&netlbl_domhsh_lock);

    return 0;
}

int netlbl_domhsh_add(struct netlbl_dom_map *entry,
              struct netlbl_audit *audit_info)
{
    int ret_val = 0;
    struct netlbl_dom_map *entry_old;
    struct netlbl_af4list *iter4;
    struct netlbl_af4list *tmp4;
#if IS_ENABLED(CONFIG_IPV6)
    struct netlbl_af6list *iter6;
    struct netlbl_af6list *tmp6;
#endif /* IPv6 */

    /* XXX - we can remove this RCU read lock as the spinlock protects the
     *       entire function, but before we do we need to fixup the
     *       netlbl_af[4,6]list RCU functions to do "the right thing" with
     *       respect to rcu_dereference() when only a spinlock is held. */
    rcu_read_lock();
    spin_lock(&netlbl_domhsh_lock);
    if (entry->domain != NULL)
        entry_old = netlbl_domhsh_search(entry->domain);
    else
        entry_old = netlbl_domhsh_search_def(entry->domain);
    if (entry_old == NULL) {
        entry->valid = 1;

        if (entry->domain != NULL) {
            u32 bkt = netlbl_domhsh_hash(entry->domain);
            list_add_tail_rcu(&entry->list,
                    &rcu_dereference(netlbl_domhsh)->tbl[bkt]);
        } else {
            INIT_LIST_HEAD(&entry->list);
            rcu_assign_pointer(netlbl_domhsh_def, entry);
        }

        if (entry->type == NETLBL_NLTYPE_ADDRSELECT) {
            netlbl_af4list_foreach_rcu(iter4,
                           &entry->type_def.addrsel->list4)
                netlbl_domhsh_audit_add(entry, iter4, NULL,
                            ret_val, audit_info);
#if IS_ENABLED(CONFIG_IPV6)
            netlbl_af6list_foreach_rcu(iter6,
                           &entry->type_def.addrsel->list6)
                netlbl_domhsh_audit_add(entry, NULL, iter6,
                            ret_val, audit_info);
#endif /* IPv6 */
        } else
            netlbl_domhsh_audit_add(entry, NULL, NULL,
                        ret_val, audit_info);
    } else if (entry_old->type == NETLBL_NLTYPE_ADDRSELECT &&
           entry->type == NETLBL_NLTYPE_ADDRSELECT) {
        struct list_head *old_list4;
        struct list_head *old_list6;

        old_list4 = &entry_old->type_def.addrsel->list4;
        old_list6 = &entry_old->type_def.addrsel->list6;

        /* we only allow the addition of address selectors if all of
         * the selectors do not exist in the existing domain map */
        netlbl_af4list_foreach_rcu(iter4,
                       &entry->type_def.addrsel->list4)
            if (netlbl_af4list_search_exact(iter4->addr,
                            iter4->mask,
                            old_list4)) {
                ret_val = -EEXIST;
                goto add_return;
            }
#if IS_ENABLED(CONFIG_IPV6)
        netlbl_af6list_foreach_rcu(iter6,
                       &entry->type_def.addrsel->list6)
            if (netlbl_af6list_search_exact(&iter6->addr,
                            &iter6->mask,
                            old_list6)) {
                ret_val = -EEXIST;
                goto add_return;
            }
#endif /* IPv6 */

        netlbl_af4list_foreach_safe(iter4, tmp4,
                        &entry->type_def.addrsel->list4) {
            netlbl_af4list_remove_entry(iter4);
            iter4->valid = 1;
            ret_val = netlbl_af4list_add(iter4, old_list4);
            netlbl_domhsh_audit_add(entry_old, iter4, NULL,
                        ret_val, audit_info);
            if (ret_val != 0)
                goto add_return;
        }
#if IS_ENABLED(CONFIG_IPV6)
        netlbl_af6list_foreach_safe(iter6, tmp6,
                        &entry->type_def.addrsel->list6) {
            netlbl_af6list_remove_entry(iter6);
            iter6->valid = 1;
            ret_val = netlbl_af6list_add(iter6, old_list6);
            netlbl_domhsh_audit_add(entry_old, NULL, iter6,
                        ret_val, audit_info);
            if (ret_val != 0)
                goto add_return;
        }
#endif /* IPv6 */
    } else
        ret_val = -EINVAL;

add_return:
    spin_unlock(&netlbl_domhsh_lock);
    rcu_read_unlock();
    return ret_val;
}

int netlbl_domhsh_add_default(struct netlbl_dom_map *entry,
                  struct netlbl_audit *audit_info)
{
    return netlbl_domhsh_add(entry, audit_info);
}

int netlbl_domhsh_remove_entry(struct netlbl_dom_map *entry,
                   struct netlbl_audit *audit_info)
{
    int ret_val = 0;
    struct audit_buffer *audit_buf;

    if (entry == NULL)
        return -ENOENT;

    spin_lock(&netlbl_domhsh_lock);
    if (entry->valid) {
        entry->valid = 0;
        if (entry != rcu_dereference(netlbl_domhsh_def))
            list_del_rcu(&entry->list);
        else
            RCU_INIT_POINTER(netlbl_domhsh_def, NULL);
    } else
        ret_val = -ENOENT;
    spin_unlock(&netlbl_domhsh_lock);

    audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info);
    if (audit_buf != NULL) {
        audit_log_format(audit_buf,
                 " nlbl_domain=%s res=%u",
                 entry->domain ? entry->domain : "(default)",
                 ret_val == 0 ? 1 : 0);
        audit_log_end(audit_buf);
    }

    if (ret_val == 0) {
        struct netlbl_af4list *iter4;
        struct netlbl_domaddr4_map *map4;

        switch (entry->type) {
        case NETLBL_NLTYPE_ADDRSELECT:
            netlbl_af4list_foreach_rcu(iter4,
                         &entry->type_def.addrsel->list4) {
                map4 = netlbl_domhsh_addr4_entry(iter4);
                cipso_v4_doi_putdef(map4->type_def.cipsov4);
            }
            /* no need to check the IPv6 list since we currently
             * support only unlabeled protocols for IPv6 */
            break;
        case NETLBL_NLTYPE_CIPSOV4:
            cipso_v4_doi_putdef(entry->type_def.cipsov4);
            break;
        }
        call_rcu(&entry->rcu, netlbl_domhsh_free_entry);
    }

    return ret_val;
}

int netlbl_domhsh_remove_af4(const char *domain,
                 const struct in_addr *addr,
                 const struct in_addr *mask,
                 struct netlbl_audit *audit_info)
{
    struct netlbl_dom_map *entry_map;
    struct netlbl_af4list *entry_addr;
    struct netlbl_af4list *iter4;
#if IS_ENABLED(CONFIG_IPV6)
    struct netlbl_af6list *iter6;
#endif /* IPv6 */
    struct netlbl_domaddr4_map *entry;

    rcu_read_lock();

    if (domain)
        entry_map = netlbl_domhsh_search(domain);
    else
        entry_map = netlbl_domhsh_search_def(domain);
    if (entry_map == NULL || entry_map->type != NETLBL_NLTYPE_ADDRSELECT)
        goto remove_af4_failure;

    spin_lock(&netlbl_domhsh_lock);
    entry_addr = netlbl_af4list_remove(addr->s_addr, mask->s_addr,
                       &entry_map->type_def.addrsel->list4);
    spin_unlock(&netlbl_domhsh_lock);

    if (entry_addr == NULL)
        goto remove_af4_failure;
    netlbl_af4list_foreach_rcu(iter4, &entry_map->type_def.addrsel->list4)
        goto remove_af4_single_addr;
#if IS_ENABLED(CONFIG_IPV6)
    netlbl_af6list_foreach_rcu(iter6, &entry_map->type_def.addrsel->list6)
        goto remove_af4_single_addr;
#endif /* IPv6 */
    /* the domain mapping is empty so remove it from the mapping table */
    netlbl_domhsh_remove_entry(entry_map, audit_info);

remove_af4_single_addr:
    rcu_read_unlock();
    /* yick, we can't use call_rcu here because we don't have a rcu head
     * pointer but hopefully this should be a rare case so the pause
     * shouldn't be a problem */
    synchronize_rcu();
    entry = netlbl_domhsh_addr4_entry(entry_addr);
    cipso_v4_doi_putdef(entry->type_def.cipsov4);
    kfree(entry);
    return 0;

remove_af4_failure:
    rcu_read_unlock();
    return -ENOENT;
}

int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
{
    int ret_val;
    struct netlbl_dom_map *entry;

    rcu_read_lock();
    if (domain)
        entry = netlbl_domhsh_search(domain);
    else
        entry = netlbl_domhsh_search_def(domain);
    ret_val = netlbl_domhsh_remove_entry(entry, audit_info);
    rcu_read_unlock();

    return ret_val;
}

int netlbl_domhsh_remove_default(struct netlbl_audit *audit_info)
{
    return netlbl_domhsh_remove(NULL, audit_info);
}

struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain)
{
    return netlbl_domhsh_search_def(domain);
}

struct netlbl_domaddr4_map *netlbl_domhsh_getentry_af4(const char *domain,
                               __be32 addr)
{
    struct netlbl_dom_map *dom_iter;
    struct netlbl_af4list *addr_iter;

    dom_iter = netlbl_domhsh_search_def(domain);
    if (dom_iter == NULL)
        return NULL;
    if (dom_iter->type != NETLBL_NLTYPE_ADDRSELECT)
        return NULL;

    addr_iter = netlbl_af4list_search(addr,
                      &dom_iter->type_def.addrsel->list4);
    if (addr_iter == NULL)
        return NULL;

    return netlbl_domhsh_addr4_entry(addr_iter);
}

#if IS_ENABLED(CONFIG_IPV6)

struct netlbl_domaddr6_map *netlbl_domhsh_getentry_af6(const char *domain,
                           const struct in6_addr *addr)
{
    struct netlbl_dom_map *dom_iter;
    struct netlbl_af6list *addr_iter;

    dom_iter = netlbl_domhsh_search_def(domain);
    if (dom_iter == NULL)
        return NULL;
    if (dom_iter->type != NETLBL_NLTYPE_ADDRSELECT)
        return NULL;

    addr_iter = netlbl_af6list_search(addr,
                      &dom_iter->type_def.addrsel->list6);
    if (addr_iter == NULL)
        return NULL;

    return netlbl_domhsh_addr6_entry(addr_iter);
}
#endif /* IPv6 */

int netlbl_domhsh_walk(u32 *skip_bkt,
             u32 *skip_chain,
             int (*callback) (struct netlbl_dom_map *entry, void *arg),
             void *cb_arg)
{
    int ret_val = -ENOENT;
    u32 iter_bkt;
    struct list_head *iter_list;
    struct netlbl_dom_map *iter_entry;
    u32 chain_cnt = 0;

    rcu_read_lock();
    for (iter_bkt = *skip_bkt;
         iter_bkt < rcu_dereference(netlbl_domhsh)->size;
         iter_bkt++, chain_cnt = 0) {
        iter_list = &rcu_dereference(netlbl_domhsh)->tbl[iter_bkt];
        list_for_each_entry_rcu(iter_entry, iter_list, list)
            if (iter_entry->valid) {
                if (chain_cnt++ < *skip_chain)
                    continue;
                ret_val = callback(iter_entry, cb_arg);
                if (ret_val < 0) {
                    chain_cnt--;
                    goto walk_return;
                }
            }
    }

walk_return:
    rcu_read_unlock();
    *skip_bkt = iter_bkt;
    *skip_chain = chain_cnt;
    return ret_val;
}