rlm_wimax.c

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/*
 *   This program is 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: 5479ace27917460a3579b4e315ebb32f441c4b3b $
 * @file rlm_wimax.c
 * @brief Supports various WiMax functionality.
 *
 * @copyright 2008 Alan DeKok (aland@networkradius.com)
 */
RCSID("$Id: 5479ace27917460a3579b4e315ebb32f441c4b3b $")
USES_APPLE_DEPRECATED_API       /* OpenSSL API has been deprecated by Apple */
 
#define LOG_PREFIX "wimax"
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/module_rlm.h>
#include <freeradius-devel/tls/base.h>
#include <freeradius-devel/util/base16.h>
 
/*
 *      FIXME: Add check for this header to configure.ac
 */
#include <freeradius-devel/tls/openssl_user_macros.h>
#include <openssl/hmac.h>
 
/*
 *      FIXME: Fix the build system to create definitions from names.
 */
typedef struct {
        bool    delete_mppe_keys;
} rlm_wimax_t;
 
static const conf_parser_t module_config[] = {
  { FR_CONF_OFFSET("delete_mppe_keys", rlm_wimax_t, delete_mppe_keys), .dflt = "no" },
        CONF_PARSER_TERMINATOR
};
 
static fr_dict_t const *dict_radius;
static fr_dict_t const *dict_freeradius;
 
extern fr_dict_autoload_t rlm_wimax_dict[];
fr_dict_autoload_t rlm_wimax_dict[] = {
        { .out = &dict_radius, .proto = "radius" },
        { .out = &dict_freeradius, .proto = "freeradius" },
        DICT_AUTOLOAD_TERMINATOR
};
 
static fr_dict_attr_t const *attr_eap_emsk;
static fr_dict_attr_t const *attr_eap_msk;
static fr_dict_attr_t const *attr_wimax_mn_nai;
 
static fr_dict_attr_t const *attr_calling_station_id;
 
static fr_dict_attr_t const *attr_wimax_msk;
static fr_dict_attr_t const *attr_wimax_ip_technology;
static fr_dict_attr_t const *attr_wimax_mn_hha_mip4_key;
static fr_dict_attr_t const *attr_wimax_mn_hha_mip4_spi;
static fr_dict_attr_t const *attr_wimax_hha_ip_mip4;
static fr_dict_attr_t const *attr_wimax_hha_ip_mip6;
static fr_dict_attr_t const *attr_wimax_mn_hha_mip6_key;
static fr_dict_attr_t const *attr_wimax_mn_hha_mip6_spi;
static fr_dict_attr_t const *attr_wimax_fa_rk_key;
static fr_dict_attr_t const *attr_wimax_fa_rk_spi;
static fr_dict_attr_t const *attr_wimax_rrq_mn_ha_spi;
static fr_dict_attr_t const *attr_wimax_rrq_ha_ip;
static fr_dict_attr_t const *attr_wimax_ha_rk_key_requested;
 
static fr_dict_attr_t const *attr_ms_mppe_send_key;
static fr_dict_attr_t const *attr_ms_mppe_recv_key;
 
extern fr_dict_attr_autoload_t rlm_wimax_dict_attr[];
fr_dict_attr_autoload_t rlm_wimax_dict_attr[] = {
        { .out = &attr_eap_emsk, .name = "EAP-EMSK", .type = FR_TYPE_OCTETS, .dict = &dict_freeradius },
        { .out = &attr_eap_msk, .name = "EAP-MSK", .type = FR_TYPE_OCTETS, .dict = &dict_freeradius },
        { .out = &attr_wimax_mn_nai, .name = "WiMAX-MN-NAI", .type = FR_TYPE_STRING, .dict = &dict_freeradius },
 
        { .out = &attr_calling_station_id, .name = "Calling-Station-ID", .type = FR_TYPE_STRING, .dict = &dict_radius },
 
        /*
         *      Load this, but we don't use it.
         */
        { .out = NULL, .name = "Vendor-Specific.WiMAX", .type = FR_TYPE_VENDOR, .dict = &dict_radius },
 
        /*
         *      Relative names are shorter.
         */
        { .out = &attr_wimax_msk, .name = ".MSK", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_wimax_ip_technology, .name = ".IP-Technology", .type = FR_TYPE_UINT32, .dict = &dict_radius },
        { .out = &attr_wimax_mn_hha_mip4_key, .name = ".MN-hHA-MIP4-Key", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_wimax_mn_hha_mip4_spi, .name = ".MN-hHA-MIP4-SPI", .type = FR_TYPE_UINT32, .dict = &dict_radius },
        { .out = &attr_wimax_hha_ip_mip4, .name = ".hHA-IP-MIP4", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_radius },
        { .out = &attr_wimax_hha_ip_mip6, .name = ".hHA-IP-MIP6", .type = FR_TYPE_IPV6_ADDR, .dict = &dict_radius },
        { .out = &attr_wimax_mn_hha_mip6_key, .name = ".MN-hHA-MIP6-Key", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_wimax_mn_hha_mip6_spi, .name = ".MN-hHA-MIP6-SPI", .type = FR_TYPE_UINT32, .dict = &dict_radius },
        { .out = &attr_wimax_fa_rk_key, .name = ".FA-RK-Key", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_wimax_fa_rk_spi, .name = ".FA-RK-SPI", .type = FR_TYPE_UINT32, .dict = &dict_radius },
        { .out = &attr_wimax_rrq_mn_ha_spi, .name = ".RRQ-MN-HA-SPI", .type = FR_TYPE_UINT32, .dict = &dict_radius },
        { .out = &attr_wimax_rrq_ha_ip, .name = ".RRQ-HA-IP", .type = FR_TYPE_COMBO_IP_ADDR, .dict = &dict_radius },
        { .out = &attr_wimax_ha_rk_key_requested, .name = ".HA-RK-Key-Requested", .type = FR_TYPE_UINT32, .dict = &dict_radius },
 
        { .out = &attr_ms_mppe_send_key, .name = "Vendor-Specific.Microsoft.MPPE-Send-Key", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_ms_mppe_recv_key, .name = "Vendor-Specific.Microsoft.MPPE-Recv-Key", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
 
        DICT_AUTOLOAD_TERMINATOR
};
 
/*
 *      Find the named user in this modules database.  Create the set
 *      of attribute-value pairs to check and reply with for this user
 *      from the database. The authentication code only needs to check
 *      the password, the rest is done here.
 */
static unlang_action_t CC_HINT(nonnull) mod_authorize(unlang_result_t *p_result, UNUSED module_ctx_t const *mctx, request_t *request)
{
        fr_pair_t *vp;
 
        /*
         *      Fix Calling-Station-Id.  Damn you, WiMAX!
         */
        vp = fr_pair_find_by_da(&request->request_pairs, NULL, attr_calling_station_id);
        if (vp && (vp->vp_length == 6)) {
                int     i;
                char    *p;
                uint8_t buffer[6];
 
                memcpy(buffer, vp->vp_strvalue, 6);
 
                MEM(fr_pair_value_bstr_realloc(vp, &p, (5 * 3) + 2) == 0);
 
                /*
                 *      RFC 3580 Section 3.20 says this is the preferred
                 *      format.  Everyone *SANE* is using this format,
                 *      so we fix it here.
                 */
                for (i = 0; i < 6; i++) {
                        fr_base16_encode(&FR_SBUFF_OUT(&p[i * 3], 2 + 1), &FR_DBUFF_TMP(&buffer[i], 1));
                        p[(i * 3) + 2] = '-';
                }
 
                DEBUG2("Fixing WiMAX binary Calling-Station-Id to %pV", &vp->data);
                RETURN_UNLANG_OK;
        }
 
        RETURN_UNLANG_NOOP;
}
 
/*
 *      Massage the request before recording it or proxying it
 */
static unlang_action_t CC_HINT(nonnull) mod_preacct(unlang_result_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        return mod_authorize(p_result, mctx, request);
}
 
/*
 *      Generate the keys after the user has been authenticated.
 */
static unlang_action_t CC_HINT(nonnull) mod_post_auth(unlang_result_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_wimax_t const       *inst = talloc_get_type_abort_const(mctx->mi->data, rlm_wimax_t);
        fr_pair_t               *msk, *emsk, *vp;
        fr_pair_t               *mn_nai, *ip, *fa_rk;
        EVP_MD_CTX              *hmac_ctx;
        EVP_PKEY                *hmac_pkey;
        uint32_t                mip_spi;
        uint8_t                 usage_data[24];
        uint8_t                 mip_rk_1[EVP_MAX_MD_SIZE], mip_rk_2[EVP_MAX_MD_SIZE];
        uint8_t                 mip_rk[2 * EVP_MAX_MD_SIZE];
        size_t                  rk1_len = sizeof(mip_rk_1), rk2_len = sizeof(mip_rk_2), rk_len = sizeof(mip_rk);
 
        msk = fr_pair_find_by_da(&request->reply_pairs, NULL, attr_eap_msk);
        emsk = fr_pair_find_by_da(&request->reply_pairs, NULL, attr_eap_emsk);
        if (!msk || !emsk) {
                REDEBUG2("No EAP-MSK or EAP-EMSK.  Cannot create WiMAX keys");
                RETURN_UNLANG_NOOP;
        }
 
        /*
         *      If we delete the MS-MPPE-*-Key attributes, then add in
         *      the WiMAX-MSK so that the client has a key available.
         */
        if (inst->delete_mppe_keys) {
                pair_delete_reply(attr_ms_mppe_send_key);
                pair_delete_reply(attr_ms_mppe_recv_key);
 
                MEM(pair_update_reply(&vp, attr_wimax_msk) >= 0);
                fr_pair_value_memdup(vp, msk->vp_octets, msk->vp_length, false);
        }
 
        /*
         *      Initialize usage data.
         */
        memcpy(usage_data, "miprk@wimaxforum.org", 21); /* with trailing \0 */
        usage_data[21] = 0x02;
        usage_data[22] = 0x00;
        usage_data[23] = 0x01;
 
        /*
         *      MIP-RK-1 = HMAC-SSHA256(EMSK, usage-data | 0x01)
         */
        MEM(hmac_ctx = EVP_MD_CTX_new());
        MEM(hmac_pkey = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, emsk->vp_octets, emsk->vp_length));
        EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha256(), NULL, hmac_pkey);
 
        EVP_DigestSignUpdate(hmac_ctx, &usage_data[0], sizeof(usage_data));
        EVP_DigestSignFinal(hmac_ctx, &mip_rk_1[0], &rk1_len);
 
        /*
         *      MIP-RK-2 = HMAC-SSHA256(EMSK, MIP-RK-1 | usage-data | 0x01)
         */
        EVP_MD_CTX_reset(hmac_ctx);
        EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha256(), NULL, hmac_pkey);
 
        EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &mip_rk_1, rk1_len);
        EVP_DigestSignUpdate(hmac_ctx, &usage_data[0], sizeof(usage_data));
        EVP_DigestSignFinal(hmac_ctx, &mip_rk_2[0], &rk2_len);
 
        memcpy(mip_rk, mip_rk_1, rk1_len);
        memcpy(mip_rk + rk1_len, mip_rk_2, rk2_len);
        rk_len = rk1_len + rk2_len;
 
        /*
         *      MIP-SPI = HMAC-SSHA256(MIP-RK, "SPI CMIP PMIP");
         */
        EVP_MD_CTX_reset(hmac_ctx);
        EVP_PKEY_free(hmac_pkey); /* No way to reset ? */
        MEM(hmac_pkey = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, mip_rk, rk_len));
        EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha256(), NULL, hmac_pkey);
 
        EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) "SPI CMIP PMIP", 12);
        EVP_DigestSignFinal(hmac_ctx, &mip_rk_1[0], &rk1_len);
 
        /*
         *      Take the 4 most significant octets.
         *      If less than 256, add 256.
         */
        mip_spi = fr_nbo_to_uint32(mip_rk_1);
        if (mip_spi < 256) mip_spi += 256;
 
        REDEBUG2("MIP-RK = 0x%pH", fr_box_octets(mip_rk, rk_len));
        REDEBUG2("MIP-SPI = %08x", ntohl(mip_spi));
 
        /*
         *      FIXME: Perform SPI collision prevention
         */
 
        /*
         *      Calculate mobility keys
         */
        mn_nai = fr_pair_find_by_da(&request->request_pairs, NULL, attr_wimax_mn_nai);
        if (!mn_nai) mn_nai = fr_pair_find_by_da(&request->reply_pairs, NULL, attr_wimax_mn_nai);
        if (!mn_nai) {
                RWDEBUG("%s was not found in the request or in the reply", attr_wimax_mn_nai->name);
                RWDEBUG("We cannot calculate MN-HA keys");
        }
 
        /*
         *      WiMAX-IP-Technology
         */
        vp = NULL;
        if (mn_nai) vp = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_wimax_ip_technology);
        if (!vp) {
                RWDEBUG("%s not found in reply", attr_wimax_ip_technology->name);
                RWDEBUG("Not calculating MN-HA keys");
        }
 
        if (vp) switch (vp->vp_uint32) {
        case 2:                 /* PMIP4 */
                /*
                 *      Look for WiMAX-hHA-IP-MIP4
                 */
                ip = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_wimax_hha_ip_mip4);
                if (!ip) {
                        RWDEBUG("%s not found.  Cannot calculate MN-HA-PMIP4 key", attr_wimax_hha_ip_mip4->name);
                        break;
                }
 
                /*
                 *      MN-HA-PMIP4 =
                 *         H(MIP-RK, "PMIP4 MN HA" | HA-IPv4 | MN-NAI);
                 */
                EVP_MD_CTX_reset(hmac_ctx);
                EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha1(), NULL, hmac_pkey);
 
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) "PMIP4 MN HA", 11);
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &ip->vp_ipv4addr, 4);
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &mn_nai->vp_strvalue, mn_nai->vp_length);
                EVP_DigestSignFinal(hmac_ctx, &mip_rk_1[0], &rk1_len);
 
                /*
                 *      Put MN-HA-PMIP4 into WiMAX-MN-hHA-MIP4-Key
                 */
                MEM(pair_update_reply(&vp, attr_wimax_mn_hha_mip4_key) >= 0);
                fr_pair_value_memdup(vp, &mip_rk_1[0], rk1_len, false);
 
                /*
                 *      Put MN-HA-PMIP4-SPI into WiMAX-MN-hHA-MIP4-SPI
                 */
                MEM(pair_update_reply(&vp, attr_wimax_mn_hha_mip4_spi) >= 0);
                vp->vp_uint32 = mip_spi + 1;
                break;
 
        case 3:                 /* CMIP4 */
                /*
                 *      Look for WiMAX-hHA-IP-MIP4
                 */
                ip = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_wimax_hha_ip_mip4);
                if (!ip) {
                        RWDEBUG("%s not found.  Cannot calculate MN-HA-CMIP4 key", attr_wimax_hha_ip_mip4->name);
                        break;
                }
 
                /*
                 *      MN-HA-CMIP4 =
                 *         H(MIP-RK, "CMIP4 MN HA" | HA-IPv4 | MN-NAI);
                 */
                EVP_MD_CTX_reset(hmac_ctx);
                EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha1(), NULL, hmac_pkey);
 
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) "CMIP4 MN HA", 11);
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &ip->vp_ipv4addr, 4);
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &mn_nai->vp_strvalue, mn_nai->vp_length);
                EVP_DigestSignFinal(hmac_ctx, &mip_rk_1[0], &rk1_len);
 
                /*
                 *      Put MN-HA-CMIP4 into WiMAX-MN-hHA-MIP4-Key
                 */
                MEM(pair_update_reply(&vp, attr_wimax_mn_hha_mip4_key) >= 0);
                fr_pair_value_memdup(vp, &mip_rk_1[0], rk1_len, false);
 
                /*
                 *      Put MN-HA-CMIP4-SPI into WiMAX-MN-hHA-MIP4-SPI
                 */
                MEM(pair_update_reply(&vp, attr_wimax_mn_hha_mip4_spi) >= 0);
                vp->vp_uint32 = mip_spi;
                break;
 
        case 4:                 /* CMIP6 */
                /*
                 *      Look for WiMAX-hHA-IP-MIP6
                 */
                ip = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_wimax_hha_ip_mip6);
                if (!ip) {
                        RWDEBUG("%s not found.  Cannot calculate MN-HA-CMIP6 key", attr_wimax_hha_ip_mip6->name);
                        break;
                }
 
                /*
                 *      MN-HA-CMIP6 =
                 *         H(MIP-RK, "CMIP6 MN HA" | HA-IPv6 | MN-NAI);
                 */
                EVP_MD_CTX_reset(hmac_ctx);
                EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha1(), NULL, hmac_pkey);
 
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) "CMIP6 MN HA", 11);
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &ip->vp_ipv6addr, 16);
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) &mn_nai->vp_strvalue, mn_nai->vp_length);
                EVP_DigestSignFinal(hmac_ctx, &mip_rk_1[0], &rk1_len);
 
                /*
                 *      Put MN-HA-CMIP6 into WiMAX-MN-hHA-MIP6-Key
                 */
                MEM(pair_update_reply(&vp, attr_wimax_mn_hha_mip6_key) >= 0);
                fr_pair_value_memdup(vp, &mip_rk_1[0], rk1_len, false);
 
                /*
                 *      Put MN-HA-CMIP6-SPI into WiMAX-MN-hHA-MIP6-SPI
                 */
                MEM(pair_update_reply(&vp, attr_wimax_mn_hha_mip6_spi) >= 0);
                vp->vp_uint32 = mip_spi + 2;
                break;
 
        default:
                break;          /* do nothing */
        }
 
        /*
         *      Generate FA-RK, if requested.
         *
         *      FA-RK= H(MIP-RK, "FA-RK")
         */
        fa_rk = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_wimax_fa_rk_key);
        if (fa_rk && (fa_rk->vp_length <= 1)) {
                EVP_MD_CTX_reset(hmac_ctx);
                EVP_DigestSignInit(hmac_ctx, NULL, EVP_sha1(), NULL, hmac_pkey);
 
                EVP_DigestSignUpdate(hmac_ctx, (uint8_t const *) "FA-RK", 5);
 
                EVP_DigestSignFinal(hmac_ctx, &mip_rk_1[0], &rk1_len);
 
                fr_pair_value_memdup(fa_rk, &mip_rk_1[0], rk1_len, false);
        }
 
        /*
         *      Create FA-RK-SPI, which is really SPI-CMIP4, which is
         *      really MIP-SPI.  Clear?  Of course.  This is WiMAX.
         */
        if (fa_rk) {
                MEM(pair_update_reply(&vp, attr_wimax_fa_rk_spi) >= 0);
                vp->vp_uint32 = mip_spi;
        }
 
        /*
         *      Give additional information about requests && responses
         *
         *      WiMAX-RRQ-MN-HA-SPI
         */
        vp = fr_pair_find_by_da_nested(&request->request_pairs, NULL, attr_wimax_rrq_mn_ha_spi);
        if (vp) {
                REDEBUG2("Client requested MN-HA key: Should use SPI to look up key from storage");
                if (!mn_nai) {
                        RWDEBUG("MN-NAI was not found!");
                }
 
                /*
                 *      WiMAX-RRQ-HA-IP
                 */
                if (!fr_pair_find_by_da_nested(&request->request_pairs, NULL, attr_wimax_rrq_ha_ip)) {
                        RWDEBUG("HA-IP was not found!");
                }
 
                /*
                 *      WiMAX-HA-RK-Key-Requested
                 */
                vp = fr_pair_find_by_da_nested(&request->request_pairs, NULL, attr_wimax_ha_rk_key_requested);
                if (vp && (vp->vp_uint32 == 1)) {
                        REDEBUG2("Client requested HA-RK: Should use IP to look it up from storage");
                }
        }
 
        /*
         *      Wipe the context of all sensitive information.
         */
        EVP_MD_CTX_free(hmac_ctx);
        EVP_PKEY_free(hmac_pkey);
 
        RETURN_UNLANG_UPDATED;
}
 
/*
 *      The module name should be the only globally exported symbol.
 *      That is, everything else should be 'static'.
 *
 *      If the module needs to temporarily modify it's instantiation
 *      data, the type should be changed to MODULE_TYPE_THREAD_UNSAFE.
 *      The server will then take care of ensuring that the module
 *      is single-threaded.
 */
extern module_rlm_t rlm_wimax;
module_rlm_t rlm_wimax = {
        .common = {
                .magic          = MODULE_MAGIC_INIT,
                .name           = "wimax",
                .inst_size      = sizeof(rlm_wimax_t),
                .config         = module_config,
        },
        .method_group = {
                .bindings = (module_method_binding_t[]){
                        { .section = SECTION_NAME("recv", "Accounting-Request"), .method = mod_preacct },
                        { .section = SECTION_NAME("recv", CF_IDENT_ANY), .method = mod_authorize },
                        { .section = SECTION_NAME("send", CF_IDENT_ANY), .method = mod_post_auth },
                        MODULE_BINDING_TERMINATOR
                }
        }
};