rlm_eap_mschapv2.c

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/*
 * rlm_eap_mschapv2.c    Handles that are called from eap
 *
 * Version:     $Id: 213568f8dbb47225a0661a20cd7d960cd4867d7e $
 *
 *   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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 *
 * @copyright 2003,2006 The FreeRADIUS server project
 */
 
RCSID("$Id: 213568f8dbb47225a0661a20cd7d960cd4867d7e $")
 
#include <freeradius-devel/server/dependency.h>
#include <freeradius-devel/server/pair.h>
#include <freeradius-devel/server/virtual_servers.h>
#include <freeradius-devel/unlang/call.h>
#include <freeradius-devel/unlang/interpret.h>
#include <freeradius-devel/util/base16.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/rand.h>
 
#include "eap_mschapv2.h"
 
static int auth_type_parse(TALLOC_CTX *ctx, void *out, UNUSED void *parent,
                           CONF_ITEM *ci, UNUSED conf_parser_t const *rule);
 
typedef struct {
        bool                    with_ntdomain_hack;
        bool                    send_error;
        char const              *identity;
        fr_dict_enum_value_t            *auth_type;
} rlm_eap_mschapv2_t;
 
static conf_parser_t submodule_config[] = {
        { FR_CONF_OFFSET("with_ntdomain_hack", rlm_eap_mschapv2_t, with_ntdomain_hack), .dflt = "no" },
 
        { FR_CONF_OFFSET_TYPE_FLAGS("auth_type", FR_TYPE_VOID, 0, rlm_eap_mschapv2_t, auth_type), .func = auth_type_parse, .dflt = "mschap" },
        { FR_CONF_OFFSET("send_error", rlm_eap_mschapv2_t, send_error), .dflt = "no" },
        { FR_CONF_OFFSET("identity", rlm_eap_mschapv2_t, identity) },
        CONF_PARSER_TERMINATOR
};
 
static fr_dict_t const *dict_freeradius;
static fr_dict_t const *dict_radius;
 
extern fr_dict_autoload_t rlm_eap_mschapv2_dict[];
fr_dict_autoload_t rlm_eap_mschapv2_dict[] = {
        { .out = &dict_freeradius, .proto = "freeradius" },
        { .out = &dict_radius, .proto = "radius" },
        { NULL }
};
 
static fr_dict_attr_t const *attr_auth_type;
static fr_dict_attr_t const *attr_ms_chap_peer_challenge;
static fr_dict_attr_t const *attr_ms_chap_user_name;
 
static fr_dict_attr_t const *attr_microsoft;
 
static fr_dict_attr_t const *attr_ms_chap_challenge;
static fr_dict_attr_t const *attr_ms_chap_error;
static fr_dict_attr_t const *attr_ms_chap_nt_enc_pw;
static fr_dict_attr_t const *attr_ms_chap2_cpw;
static fr_dict_attr_t const *attr_ms_chap2_response;
static fr_dict_attr_t const *attr_ms_chap2_success;
static fr_dict_attr_t const *attr_ms_mppe_encryption_policy;
static fr_dict_attr_t const *attr_ms_mppe_encryption_type;
static fr_dict_attr_t const *attr_ms_mppe_send_key;
static fr_dict_attr_t const *attr_ms_mppe_recv_key;
static fr_dict_attr_t const *attr_state;
static fr_dict_attr_t const *attr_user_name;
 
extern fr_dict_attr_autoload_t rlm_eap_mschapv2_dict_attr[];
fr_dict_attr_autoload_t rlm_eap_mschapv2_dict_attr[] = {
        { .out = &attr_auth_type, .name = "Auth-Type", .type = FR_TYPE_UINT32, .dict = &dict_freeradius },
        { .out = &attr_ms_chap_peer_challenge, .name = "MS-CHAP-Peer-Challenge", .type = FR_TYPE_OCTETS, .dict = &dict_freeradius },
        { .out = &attr_ms_chap_user_name, .name = "MS-CHAP-User-Name", .type = FR_TYPE_STRING, .dict = &dict_freeradius },
 
        { .out = &attr_microsoft, .name = "Vendor-Specific.Microsoft", .type = FR_TYPE_VENDOR, .dict = &dict_radius },
 
        { .out = &attr_ms_chap_challenge, .name = "Vendor-Specific.Microsoft.CHAP-Challenge", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_ms_chap_error, .name = "Vendor-Specific.Microsoft.CHAP-Error", .type = FR_TYPE_STRING, .dict = &dict_radius },
        { .out = &attr_ms_chap_nt_enc_pw, .name = "Vendor-Specific.Microsoft.CHAP-NT-Enc-PW", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_ms_chap2_cpw, .name = "Vendor-Specific.Microsoft.CHAP2-CPW", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_ms_chap2_response, .name = "Vendor-Specific.Microsoft.CHAP2-Response", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_ms_chap2_success, .name = "Vendor-Specific.Microsoft.CHAP2-Success", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_ms_mppe_encryption_policy, .name = "Vendor-Specific.Microsoft.MPPE-Encryption-Policy", .type = FR_TYPE_UINT32, .dict = &dict_radius },
        { .out = &attr_ms_mppe_encryption_type, .name = "Vendor-Specific.Microsoft.MPPE-Encryption-Type", .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 },
        { .out = &attr_state, .name = "State", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
        { .out = &attr_user_name, .name = "User-Name", .type = FR_TYPE_STRING, .dict = &dict_radius },
        { NULL }
};
 
static void mppe_keys_store(request_t *request, mschapv2_opaque_t *data)
{
        fr_pair_t *parent;
 
        RDEBUG2("Storing attributes for final response");
 
        parent = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_microsoft);
        if (!parent) parent = request->reply_ctx;
 
        RINDENT();
        if (fr_pair_list_copy_by_da(data, &data->mppe_keys, &parent->vp_group,
                                    attr_ms_mppe_encryption_policy, 0) > 0) {
                RDEBUG2("%s", attr_ms_mppe_encryption_policy->name);
        }
        if (fr_pair_list_copy_by_da(data, &data->mppe_keys, &parent->vp_group,
                                    attr_ms_mppe_encryption_type, 0) > 0) {
                RDEBUG2("%s", attr_ms_mppe_encryption_type->name);
        }
        if (fr_pair_list_copy_by_da(data, &data->mppe_keys, &parent->vp_group,
                                    attr_ms_mppe_recv_key, 0) > 0) {
                RDEBUG2("%s", attr_ms_mppe_recv_key->name);
        }
        if (fr_pair_list_copy_by_da(data, &data->mppe_keys, &parent->vp_group,
                                    attr_ms_mppe_send_key, 0) > 0) {
                RDEBUG2("%s", attr_ms_mppe_send_key->name);
        }
        REXDENT();
}
 
/** Translate a string auth_type into an enumeration value
 *
 * @param[in] ctx       to allocate data.
 * @param[out] out      Where to write the auth_type we created or resolved.
 * @param[in] parent    Base structure address.
 * @param[in] ci        #CONF_PAIR specifying the name of the auth_type.
 * @param[in] rule      unused.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int auth_type_parse(UNUSED TALLOC_CTX *ctx, void *out, UNUSED void *parent,
                           CONF_ITEM *ci, UNUSED conf_parser_t const *rule)
{
        char const      *auth_type = cf_pair_value(cf_item_to_pair(ci));
 
        if (fr_dict_enum_add_name_next(fr_dict_attr_unconst(attr_auth_type), auth_type) < 0) {
                cf_log_err(ci, "Failed adding %s alias", attr_auth_type->name);
                return -1;
        }
        *((fr_dict_enum_value_t **)out) = UNCONST(fr_dict_enum_value_t *, fr_dict_enum_by_name(attr_auth_type, auth_type, -1));
 
        return 0;
}
 
/*
 *      Compose the response.
 */
static int eap_mschapv2_compose(rlm_eap_mschapv2_t const *inst, request_t *request, eap_session_t *eap_session,
                               fr_pair_t *reply) CC_HINT(nonnull);
static int eap_mschapv2_compose(rlm_eap_mschapv2_t const *inst, request_t *request, eap_session_t *eap_session,
                               fr_pair_t *reply)
{
        uint8_t                 *ptr;
        int16_t                 length;
        mschapv2_header_t       *hdr;
        eap_round_t             *eap_round = eap_session->this_round;
 
        eap_round->request->code = FR_EAP_CODE_REQUEST;
        eap_round->request->type.num = FR_EAP_METHOD_MSCHAPV2;
 
        /*
         *      Always called with vendor Microsoft
         */
        if (reply->da == attr_ms_chap_challenge) {
                /*
                 *   0                   1                   2                   3
                 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |     Code      |   Identifier  |            Length             |
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |     Type      |   OpCode      |  MS-CHAPv2-ID |  MS-Length...
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |   MS-Length   |  Value-Size   |  Challenge...
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |                             Challenge...
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |                             Server Name...
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 */
                length = MSCHAPV2_HEADER_LEN + MSCHAPV2_CHALLENGE_LEN + (talloc_array_length(inst->identity) - 1);
                eap_round->request->type.data = talloc_array(eap_round->request, uint8_t, length);
 
                /*
                 *      Allocate room for the EAP-MS-CHAPv2 data.
                 */
                if (!eap_round->request->type.data) return -1;
                eap_round->request->type.length = length;
 
                ptr = eap_round->request->type.data;
                hdr = (mschapv2_header_t *) ptr;
 
                hdr->opcode = FR_EAP_MSCHAPV2_CHALLENGE;
                hdr->mschapv2_id = eap_round->response->id + 1;
                length = htons(length);
                memcpy(hdr->ms_length, &length, sizeof(uint16_t));
                hdr->value_size = MSCHAPV2_CHALLENGE_LEN;
 
                ptr += MSCHAPV2_HEADER_LEN;
 
                /*
                 *      Copy the Challenge, success, or error over.
                 */
                memcpy(ptr, reply->vp_octets, reply->vp_length);
                memcpy((ptr + reply->vp_length), inst->identity, (talloc_array_length(inst->identity) - 1));
        } else if (reply->da == attr_ms_chap2_success) {
                /*
                 *   0                   1                   2                   3
                 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |     Code      |   Identifier  |            Length             |
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |     Type      |   OpCode      |  MS-CHAPv2-ID |  MS-Length...
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 *  |   MS-Length   |                    Message...
                 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 */
                RDEBUG2("MS-CHAPv2 Success");
                length = 46;
                eap_round->request->type.data = talloc_array(eap_round->request, uint8_t, length);
                /*
                 *      Allocate room for the EAP-MS-CHAPv2 data.
                 */
                if (!eap_round->request->type.data) return -1;
                memset(eap_round->request->type.data, 0, length);
                eap_round->request->type.length = length;
 
                eap_round->request->type.data[0] = FR_EAP_MSCHAPV2_SUCCESS;
                eap_round->request->type.data[1] = eap_round->response->id;
                length = htons(length);
                memcpy((eap_round->request->type.data + 2), &length, sizeof(uint16_t));
                memcpy((eap_round->request->type.data + 4), reply->vp_strvalue + 1, 42);
        } else if (reply->da == attr_ms_chap_error) {
                REDEBUG("MS-CHAPv2 Failure");
                length = 4 + reply->vp_length - 1;
                eap_round->request->type.data = talloc_array(eap_round->request, uint8_t, length);
 
                /*
                 *      Allocate room for the EAP-MS-CHAPv2 data.
                 */
                if (!eap_round->request->type.data) return 0;
                memset(eap_round->request->type.data, 0, length);
                eap_round->request->type.length = length;
 
                eap_round->request->type.data[0] = FR_EAP_MSCHAPV2_FAILURE;
                eap_round->request->type.data[1] = eap_round->response->id;
                length = htons(length);
                memcpy((eap_round->request->type.data + 2), &length, sizeof(uint16_t));
                /*
                 *      Copy the entire failure message.
                 */
                memcpy((eap_round->request->type.data + 4), reply->vp_strvalue + 1, reply->vp_length - 1);
        } else {
                RERROR("%s: Internal sanity check failed", __FUNCTION__);
                return -1;
        }
 
        return 0;
}
 
 
static unlang_action_t CC_HINT(nonnull) mod_process(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request);
 
static unlang_action_t mschap_resume(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        eap_session_t                   *eap_session = mctx->rctx;
        mschapv2_opaque_t               *data = talloc_get_type_abort(eap_session->opaque, mschapv2_opaque_t);
        eap_round_t                     *eap_round = eap_session->this_round;
        fr_pair_list_t                  response;
        rlm_eap_mschapv2_t const        *inst = mctx->mi->data;
        rlm_rcode_t                     rcode;
        fr_pair_t *parent;
 
        fr_pair_list_init(&response);
 
        rcode = unlang_interpret_stack_result(request);
 
        /*
         *      Delete MPPE keys & encryption policy.  We don't
         *      want these here.
         */
        mppe_keys_store(request, data);
 
        parent = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_microsoft);
        if (!parent) parent = request->reply_ctx;
 
        /*
         *      Take the response from the mschap module, and
         *      return success or failure, depending on the result.
         */
        if (rcode == RLM_MODULE_OK) {
                if (fr_pair_list_copy_by_da(data, &response, &parent->vp_group, attr_ms_chap2_success, 0) < 0) {
                        RPERROR("Failed copying %s", attr_ms_chap2_success->name);
                        RETURN_MODULE_FAIL;
                }
 
                data->code = FR_EAP_MSCHAPV2_SUCCESS;
        } else if (inst->send_error) {
                if (fr_pair_list_copy_by_da(data, &response, &parent->vp_group, attr_ms_chap_error, 0) < 0) {
                        RPERROR("Failed copying %s", attr_ms_chap_error->name);
                        RETURN_MODULE_FAIL;
                }
                if (!fr_pair_list_empty(&response)) {
                        int n, err, retry;
                        char buf[34];
                        fr_pair_t *vp = fr_pair_list_head(&response);
 
                        PAIR_VERIFY(vp);
 
                        RDEBUG2("MSCHAP-Error: %pV", &vp->data);
 
                        /*
                         *      Parse the new challenge out of the
                         *      MS-CHAP-Error, so that if the client
                         *      issues a re-try, we will know which
                         *      challenge value that they used.
                         */
                        n = sscanf(vp->vp_strvalue, "%*cE=%d R=%d C=%32s", &err, &retry, &buf[0]);
                        if (n == 3) {
                                RDEBUG2("Found new challenge from MS-CHAP-Error: err=%d retry=%d challenge=%s",
                                        err, retry, buf);
                                fr_base16_decode(NULL, &FR_DBUFF_TMP(data->auth_challenge, 16),
                                           &FR_SBUFF_IN(buf, strlen(buf)), false);
                        } else {
                                RDEBUG2("Could not parse new challenge from MS-CHAP-Error: %d", n);
                        }
                }
                data->code = FR_EAP_MSCHAPV2_FAILURE;
        } else {
                eap_round->request->code = FR_EAP_CODE_FAILURE;
                RETURN_MODULE_REJECT;
        }
 
        /*
         *      No response, die.
         */
        if (fr_pair_list_empty(&response)) {
                REDEBUG("No %s or %s attributes were found", attr_ms_chap2_success->name, attr_ms_chap_error->name);
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      Compose the response (whatever it is),
         *      and return it to the over-lying EAP module.
         */
        eap_mschapv2_compose(eap_session->inst, request, eap_session, fr_pair_list_head(&response));
        fr_pair_list_free(&response);
 
        RETURN_MODULE_OK;
}
 
/*
 *      Authenticate a previously sent challenge.
 */
static unlang_action_t CC_HINT(nonnull) mod_process(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_eap_mschapv2_t const        *inst = talloc_get_type_abort(mctx->mi->data, rlm_eap_mschapv2_t);
        request_t                       *parent = request->parent;
        eap_session_t                   *eap_session = eap_session_get(parent);
        mschapv2_opaque_t               *data = talloc_get_type_abort(eap_session->opaque, mschapv2_opaque_t);
        eap_round_t                     *eap_round = eap_session->this_round;
        fr_pair_t                       *auth_challenge, *response, *name;
 
        CONF_SECTION                    *unlang;
        int                             ccode;
        uint8_t                         *p;
        size_t                          length;
 
        if (!fr_cond_assert(eap_session->inst)) RETURN_MODULE_FAIL;
 
        /*
         *      Sanity check the response.
         */
        if (eap_round->response->length < 6) {
                REDEBUG("Response too short, expected at least 6 bytes, got %zu bytes",
                        eap_round->response->length);
                RETURN_MODULE_INVALID;
        }
 
        ccode = eap_round->response->type.data[0];
 
        switch (data->code) {
        case FR_EAP_MSCHAPV2_FAILURE:
                if (ccode == FR_EAP_MSCHAPV2_RESPONSE) {
                        RDEBUG2("Authentication re-try from client after we sent a failure");
                        break;
                }
 
                /*
                 * if we sent error 648 (password expired) to the client
                 * we might get an MSCHAP-CPW packet here; turn it into a
                 * regular MS-CHAP2-CPW packet and pass it to rlm_mschap
                 * (or proxy it, I guess)
                 */
                if (ccode == FR_EAP_MSCHAPV2_CHGPASSWD) {
                        fr_pair_t       *cpw;
                        int             mschap_id = eap_round->response->type.data[1];
                        int             copied = 0;
                        int             seq = 1;
                        fr_pair_t       *ms;
 
                        RDEBUG2("Password change packet received");
 
                        MEM(pair_update_request(&auth_challenge, attr_ms_chap_challenge) >= 0);
                        fr_pair_value_memdup(auth_challenge, data->auth_challenge, MSCHAPV2_CHALLENGE_LEN, false);
 
                        MEM(pair_update_request(&cpw, attr_ms_chap2_cpw) >= 0);
                        MEM(fr_pair_value_mem_alloc(cpw, &p, 68, false) == 0);
                        p[0] = 7;
                        p[1] = mschap_id;
                        memcpy(p + 2, eap_round->response->type.data + 520, 66);
 
                        ms = fr_pair_find_by_da_nested(&request->request_pairs, NULL, attr_microsoft);
                        if (!ms) ms = request->request_ctx;
 
                        /*
                         * break the encoded password into VPs (3 of them)
                         */
                        while (copied < 516) {
                                fr_pair_t *nt_enc;
 
                                int to_copy = 516 - copied;
                                if (to_copy > 243) to_copy = 243;
 
                                MEM(nt_enc = fr_pair_afrom_da(ms, attr_ms_chap_nt_enc_pw));
                                MEM(fr_pair_value_mem_alloc(nt_enc, &p, 4 + to_copy, false) == 0);
                                MEM(fr_pair_append(&ms->vp_group, nt_enc) == 0);
                                p[0] = 6;
                                p[1] = mschap_id;
                                p[2] = 0;
                                p[3] = seq++;
                                memcpy(p + 4, eap_round->response->type.data + 4 + copied, to_copy);
 
                                copied += to_copy;
                        }
 
                        RDEBUG2("Built change password packet");
                        log_request_pair_list(L_DBG_LVL_2, request, NULL, &request->request_pairs, NULL);
 
                        /*
                         * jump to "authentication"
                         */
                        goto packet_ready;
                }
 
                /*
                 * we sent a failure and are expecting a failure back
                 */
                if (ccode != FR_EAP_MSCHAPV2_FAILURE) {
                        REDEBUG("Sent FAILURE expecting FAILURE but got %d", ccode);
                        RETURN_MODULE_INVALID;
                }
 
failure:
                eap_round->request->code = FR_EAP_CODE_FAILURE;
                RETURN_MODULE_REJECT;
 
        case FR_EAP_MSCHAPV2_SUCCESS:
                /*
                 * we sent a success to the client; some clients send a
                 * success back as-per the RFC, some send an ACK. Permit
                 * both, I guess...
                 */
 
                switch (ccode) {
                case FR_EAP_MSCHAPV2_SUCCESS:
                        eap_round->request->code = FR_EAP_CODE_SUCCESS;
 
                        if (!fr_pair_list_empty(&data->mppe_keys)) {
                                fr_pair_t *ms;
 
                                ms = fr_pair_find_by_da_nested(&parent->reply_pairs, NULL, attr_microsoft);
                                if (!ms) {
                                        MEM(ms = fr_pair_afrom_da_nested(parent->reply_ctx, &parent->reply_pairs, attr_microsoft));
                                }
 
                                RDEBUG2("Adding stored attributes to parent");
                                log_request_pair_list(L_DBG_LVL_2, request, NULL, &data->mppe_keys, "parent.reply.");
                                MEM(fr_pair_list_copy(ms, &ms->vp_group, &data->mppe_keys) >= 0);
                        } else {
                                RDEBUG2("No stored attributes to copy to parent");
                        }
 
                        FALL_THROUGH;
 
                case FR_EAP_MSCHAPV2_ACK:
                        MEM(fr_pair_list_copy(parent->reply_ctx, &parent->reply_pairs, &data->reply) >= 0);
                        RETURN_MODULE_OK;
                }
                REDEBUG("Sent SUCCESS expecting SUCCESS (or ACK) but got %d", ccode);
                RETURN_MODULE_INVALID;
 
        case FR_EAP_MSCHAPV2_CHALLENGE:
                if (ccode == FR_EAP_MSCHAPV2_FAILURE) goto failure;
 
                /*
                 * we sent a challenge, expecting a response
                 */
                if (ccode != FR_EAP_MSCHAPV2_RESPONSE) {
                        REDEBUG("Sent CHALLENGE expecting RESPONSE but got %d", ccode);
                        RETURN_MODULE_INVALID;
                }
                /* authentication happens below */
                break;
 
        default:
                /* should never happen */
                REDEBUG("Unknown state %d", data->code);
                RETURN_MODULE_FAIL;
        }
 
 
        /*
         *      Ensure that we have at least enough data
         *      to do the following checks.
         *
         *      EAP header (4), EAP type, MS-CHAP opcode,
         *      MS-CHAP ident, MS-CHAP data length (2),
         *      MS-CHAP value length.
         */
        if (eap_round->response->length < (4 + 1 + 1 + 1 + 2 + 1)) {
                REDEBUG("Response is too short");
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      The 'value_size' is the size of the response,
         *      which is supposed to be the response (48
         *      bytes) plus 1 byte of flags at the end.
         *
         *      NOTE: When using Cisco NEAT with EAP-MSCHAPv2, the
         *            switch supplicant will send MSCHAPv2 data (EAP type = 26)
         *            but will always set a value_size of 16 and NULL out the
         *            peer challenge.
         *
         */
        if ((eap_round->response->type.data[4] != 49) &&
            (eap_round->response->type.data[4] != 16)) {
                REDEBUG("Response is of incorrect length %d", eap_round->response->type.data[4]);
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      The MS-Length field is 5 + value_size + length
         *      of name, which is put after the response.
         */
        length = fr_nbo_to_uint16(eap_round->response->type.data + 2);
        if ((length < (5 + 49)) || (length > (256 + 5 + 49))) {
                REDEBUG("Response contains contradictory length %zu %d", length, 5 + 49);
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      We now know that the user has sent us a response
         *      to the challenge.  Let's try to authenticate it.
         *
         *      We do this by taking the challenge from 'data',
         *      the response from the EAP packet, and creating fr_pair_t's
         *      to pass to the 'mschap' module.  This is a little wonky,
         *      but it works.
         */
        MEM(pair_update_request(&auth_challenge, attr_ms_chap_challenge) >= 0);
        fr_pair_value_memdup(auth_challenge, data->auth_challenge, MSCHAPV2_CHALLENGE_LEN, false);
 
        MEM(pair_update_request(&response, attr_ms_chap2_response) >= 0);
        MEM(fr_pair_value_mem_alloc(response, &p, MSCHAPV2_RESPONSE_LEN, false) == 0);
        p[0] = eap_round->response->type.data[1];
        p[1] = eap_round->response->type.data[5 + MSCHAPV2_RESPONSE_LEN];
        memcpy(p + 2, &eap_round->response->type.data[5], MSCHAPV2_RESPONSE_LEN - 2);
 
        /*
         *      If we're forcing a peer challenge, use it instead of
         *      the challenge sent by the client.
         */
        if (data->has_peer_challenge) memcpy(p + 2, data->peer_challenge, MSCHAPV2_CHALLENGE_LEN);
 
        /*
         *      MS-Length - MS-Value - 5.
         */
        MEM(pair_update_request(&name, attr_ms_chap_user_name) >= 0);
        MEM(fr_pair_value_bstrndup(name, (char const *)&eap_round->response->type.data[4 + MSCHAPV2_RESPONSE_LEN],
                                   length - 49 - 5, true) == 0);
packet_ready:
 
        /*
         *      Look for "authenticate foo" in the current virtual
         *      server.  If not there, then in the parent one.
         */
        RDEBUG("Looking for authenticate %s { ... }", inst->auth_type->name);
        unlang = cf_section_find(unlang_call_current(parent), "authenticate", inst->auth_type->name);
        if (!unlang) unlang = cf_section_find(unlang_call_current(request->parent), "authenticate", inst->auth_type->name);
        if (!unlang) {
                RDEBUG2("authenticate %s { ... } sub-section not found.",
                        inst->auth_type->name);
                RETURN_MODULE_FAIL;
        }
 
        return unlang_module_yield_to_section(p_result, request, unlang, RLM_MODULE_FAIL, mschap_resume, NULL, 0, eap_session);
}
 
/*
 *      Initiate the EAP-MSCHAPV2 session by sending a challenge to the peer.
 */
static unlang_action_t mod_session_init(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        request_t                       *parent = request->parent;
        eap_session_t           *eap_session = eap_session_get(parent);
        fr_pair_t               *auth_challenge;
        fr_pair_t               *peer_challenge;
        mschapv2_opaque_t       *data;
 
        uint8_t                 *p;
        int                     i;
        bool                    created_auth_challenge;
 
        if (!fr_cond_assert(mctx->mi->data)) RETURN_MODULE_FAIL;
 
        /*
         *      We're looking for attributes that should come
         *      from the EAP-TTLS submodule.
         */
        if (!fr_cond_assert(parent)) RETURN_MODULE_FAIL;
 
        /*
         *      Keep track of the challenge and the state we are in.
         */
        MEM(data = talloc_zero(eap_session, mschapv2_opaque_t));
        data->code = FR_EAP_MSCHAPV2_CHALLENGE;
        fr_pair_list_init(&data->mppe_keys);
        fr_pair_list_init(&data->reply);
 
        /*
         *      Allow the administrator to set the CHAP-Challenge and Peer-Challenge attributes.
         */
        auth_challenge = fr_pair_find_by_da_nested(&parent->control_pairs, NULL, attr_ms_chap_challenge);
        if (auth_challenge && (auth_challenge->vp_length != MSCHAPV2_CHALLENGE_LEN)) {
                RWDEBUG("parent.control.MS-CHAP-Challenge is incorrect length.  Ignoring it");
                auth_challenge = NULL;
        }
 
        peer_challenge = fr_pair_find_by_da_nested(&parent->control_pairs, NULL, attr_ms_chap_peer_challenge);
        if (peer_challenge && (peer_challenge->vp_length != MSCHAPV2_CHALLENGE_LEN)) {
                RWDEBUG("parent.control.MS-CHAP-Peer-Challenge is incorrect length.  Ignoring it");
                peer_challenge = NULL;
        }
 
        created_auth_challenge = (auth_challenge == NULL);
 
        /*
         *      if the administrator didn't set a challenge, then create one ourselves.
         */
        if (!auth_challenge) {
                MEM(auth_challenge = fr_pair_afrom_da(eap_session, attr_ms_chap_challenge));
                MEM(fr_pair_value_mem_alloc(auth_challenge, &p, MSCHAPV2_CHALLENGE_LEN, false) == 0);
                for (i = 0; i < MSCHAPV2_CHALLENGE_LEN; i++) p[i] = fr_rand();
        }
        RDEBUG2("Issuing Challenge");
 
        /*
         *      We're at the stage where we're challenging the user.
         */
        memcpy(data->auth_challenge, auth_challenge->vp_octets, MSCHAPV2_CHALLENGE_LEN);
 
        if (peer_challenge) {
                data->has_peer_challenge = true;
                memcpy(data->peer_challenge, peer_challenge->vp_octets, MSCHAPV2_CHALLENGE_LEN);
        }
 
        eap_session->opaque = data;
 
        /*
         *      Compose the EAP-MSCHAPV2 packet out of the data structure,
         *      and free it.
         */
        eap_mschapv2_compose(mctx->mi->data, request, eap_session, auth_challenge);
        if (created_auth_challenge) TALLOC_FREE(auth_challenge);
 
        /*
         *      We don't need to authorize the user at this point.
         *
         *      We also don't need to keep the challenge, as it's
         *      stored in 'eap_session->this_round', which will be given back
         *      to us...
         */
        eap_session->process = mod_process;
 
        RETURN_MODULE_HANDLED;
}
 
/*
 *      Attach the module.
 */
static int mod_instantiate(module_inst_ctx_t const *mctx)
{
        rlm_eap_mschapv2_t *inst = talloc_get_type_abort(mctx->mi->data, rlm_eap_mschapv2_t);
 
        if (inst->identity && (strlen(inst->identity) > 255)) {
                cf_log_err(mctx->mi->conf, "identity is too long");
                return -1;
        }
 
        if (!inst->identity) inst->identity = talloc_typed_asprintf(inst, "freeradius-%s", RADIUSD_VERSION_STRING);
 
        return 0;
}
 
/*
 *      The module name should be the only globally exported symbol.
 *      That is, everything else should be 'static'.
 */
extern rlm_eap_submodule_t rlm_eap_mschapv2;
rlm_eap_submodule_t rlm_eap_mschapv2 = {
        .common = {
                .name           = "eap_mschapv2",
                .magic          = MODULE_MAGIC_INIT,
                .inst_size      = sizeof(rlm_eap_mschapv2_t),
                .config         = submodule_config,
                .instantiate    = mod_instantiate,      /* Create new submodule instance */
        },
        .provides       = { FR_EAP_METHOD_MSCHAPV2 },
        .session_init   = mod_session_init,     /* Initialise a new EAP session */
        .clone_parent_lists = false             /* HACK */
};