peap.c

Go to the documentation of this file.

/*
 * peap.c contains the interfaces that are called from eap
 *
 * Version:     $Id: 02eecbca33fd5b9d307addcecbeb5b1d5be2b00f $
 *
 *   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 Alan DeKok (aland@freeradius.org)
 *   @copyright 2006 The FreeRADIUS server project
 */
 
RCSID("$Id: 02eecbca33fd5b9d307addcecbeb5b1d5be2b00f $")
USES_APPLE_DEPRECATED_API       /* OpenSSL API has been deprecated by Apple */
 
#include <freeradius-devel/radius/radius.h>
#include <freeradius-devel/radius/defs.h>
 
#include "eap_peap.h"
 
static int setup_fake_request(request_t *request, request_t *fake, peap_tunnel_t *t);
 
/*
 *      Send protected EAP-Failure
 *
 *       Result-TLV = Failure
 */
static int eap_peap_failure(request_t *request, eap_session_t *eap_session, fr_tls_session_t *tls_session)
{
        uint8_t tlv_packet[11];
 
        RDEBUG2("FAILURE");
 
        tlv_packet[0] = FR_EAP_CODE_REQUEST;
        tlv_packet[1] = eap_session->this_round->response->id +1;
        tlv_packet[2] = 0;
        tlv_packet[3] = 11;     /* length of this packet */
        tlv_packet[4] = FR_PEAP_EXTENSIONS_TYPE;
        tlv_packet[5] = 0x80;
        tlv_packet[6] = EAP_TLV_ACK_RESULT;
        tlv_packet[7] = 0;
        tlv_packet[8] = 2;      /* length of the data portion */
        tlv_packet[9] = 0;
        tlv_packet[10] = EAP_TLV_FAILURE;
 
        (tls_session->record_from_buff)(&tls_session->clean_in, tlv_packet, 11);
 
        /*
         *      FIXME: Check the return code.
         */
        fr_tls_session_send(request, tls_session);
 
        return 1;
}
 
 
/*
 *      Send protected EAP-Success
 *
 *       Result-TLV = Success
 */
static int eap_peap_success(request_t *request, eap_session_t *eap_session, fr_tls_session_t *tls_session)
{
        uint8_t tlv_packet[11];
 
        RDEBUG2("SUCCESS");
 
        tlv_packet[0] = FR_EAP_CODE_REQUEST;
        tlv_packet[1] = eap_session->this_round->response->id +1;
        tlv_packet[2] = 0;
        tlv_packet[3] = 11;     /* length of this packet */
        tlv_packet[4] = FR_PEAP_EXTENSIONS_TYPE;
        tlv_packet[5] = 0x80;   /* mandatory AVP */
        tlv_packet[6] = EAP_TLV_ACK_RESULT;
        tlv_packet[7] = 0;
        tlv_packet[8] = 2;      /* length of the data portion */
        tlv_packet[9] = 0;
        tlv_packet[10] = EAP_TLV_SUCCESS;
 
        (tls_session->record_from_buff)(&tls_session->clean_in, tlv_packet, 11);
 
        /*
         *      FIXME: Check the return code.
         */
        fr_tls_session_send(request, tls_session);
 
        return 1;
}
 
 
static int eap_peap_identity(request_t *request, eap_session_t *eap_session, fr_tls_session_t *tls_session)
{
        eap_packet_raw_t eap_packet;
 
        eap_packet.code = FR_EAP_CODE_REQUEST;
        eap_packet.id = eap_session->this_round->response->id + 1;
        eap_packet.length[0] = 0;
        eap_packet.length[1] = EAP_HEADER_LEN + 1;
        eap_packet.data[0] = FR_EAP_METHOD_IDENTITY;
 
        (tls_session->record_from_buff)(&tls_session->clean_in, &eap_packet, sizeof(eap_packet));
        fr_tls_session_send(request, tls_session);
        (tls_session->record_init)(&tls_session->clean_in);
 
        return 1;
}
 
/*
 *      Verify the tunneled EAP message.
 */
static int eap_peap_verify(request_t *request, peap_tunnel_t *peap_tunnel,
                           uint8_t const *data, size_t data_len)
{
        eap_packet_raw_t const  *eap_packet = (eap_packet_raw_t const *) data;
        eap_type_t              eap_method;
 
        /*
         *      No data, OR only 1 byte of EAP type.
         */
        if (!data || (data_len == 0) || ((data_len <= 1) && (data[0] != FR_EAP_METHOD_IDENTITY))) return 0;
 
        /*
         *  Since the full EAP header is sent for the EAP Extensions type (Type 33),
         *  but not for other Types, it is difficult for the implementation to distinguish
         *  an Extensions Request (Code 1) from an EAP Type 1 (Identity) Request packet.
         *
         *  i.e. The only way to validate PEAP inner method packets properly is to know
         *  we just send a protected success/failure.
         */
        switch (peap_tunnel->status) {
        case PEAP_STATUS_SENT_TLV_SUCCESS:
        case PEAP_STATUS_SENT_TLV_FAILURE:
                if (eap_packet->data[0] != FR_PEAP_EXTENSIONS_TYPE) {
                        REDEBUG("Invalid inner tunnel data, expected method (%u), got (%u)",
                                FR_PEAP_EXTENSIONS_TYPE, eap_packet->data[0]);
                        return -1;
                }
                return 0;
 
        default:
                break;
        }
 
        eap_method = data[0];   /* Inner EAP header misses off code and identifier */
        switch (eap_method) {
        case FR_EAP_METHOD_IDENTITY:
                RDEBUG2("Received EAP-Identity-Response");
                return 0;
 
        /*
         *      We normally do Microsoft MS-CHAPv2 (26), versus
         *      Cisco MS-CHAPv2 (29).
         */
        case FR_EAP_METHOD_MSCHAPV2:
        default:
                RDEBUG2("EAP method %s (%d)", eap_type2name(eap_method), eap_method);
                return 0;
        }
 
}
 
/*
 *      Convert a pseudo-EAP packet to a list of fr_pair_t's.
 */
static void eap_peap_inner_to_pairs(TALLOC_CTX *ctx, fr_pair_list_t *pairs,
                                    eap_round_t *eap_round,
                                    uint8_t const *data, size_t data_len)
{
        size_t          total;
        uint8_t         *p;
        fr_pair_t       *vp = NULL;
 
        if (data_len > 65535) return; /* paranoia */
 
        MEM(vp = fr_pair_afrom_da(ctx, attr_eap_message));
        total = data_len;
        if (total > 249) total = 249;
 
        /*
         *      Hand-build an EAP packet from the crap in PEAP version 0.
         */
        MEM(fr_pair_value_mem_alloc(vp, &p, EAP_HEADER_LEN + total, false) == 0);
        p[0] = FR_EAP_CODE_RESPONSE;
        p[1] = eap_round->response->id;
        p[2] = (data_len + EAP_HEADER_LEN) >> 8;
        p[3] = (data_len + EAP_HEADER_LEN) & 0xff;
        memcpy(p + EAP_HEADER_LEN, data, total);
 
        fr_pair_append(pairs, vp);
        while (total < data_len) {
                MEM(vp = fr_pair_afrom_da(ctx, attr_eap_message));
                fr_pair_value_memdup(vp, data + total, (data_len - total), false);
 
                total += vp->vp_length;
 
                fr_pair_append(pairs, vp);
        }
}
 
 
/*
 *      Convert a list of fr_pair_t's to an EAP packet, through the
 *      simple expedient of dumping the EAP message
 */
static int eap_peap_inner_from_pairs(request_t *request, fr_tls_session_t *tls_session, fr_pair_list_t *vps)
{
        fr_pair_t *this;
 
        fr_assert(!fr_pair_list_empty(vps));
 
        /*
         *      Send the EAP data in the first attribute, WITHOUT the
         *      header.
         */
        this = fr_pair_list_head(vps);
        (tls_session->record_from_buff)(&tls_session->clean_in, this->vp_octets + EAP_HEADER_LEN,
                                        this->vp_length - EAP_HEADER_LEN);
 
        /*
         *      Send the rest of the EAP data, but skipping the first VP.
         */
        for (this = fr_pair_list_next(vps, this);
             this;
             this = fr_pair_list_next(vps, this)) {
                (tls_session->record_from_buff)(&tls_session->clean_in, this->vp_octets, this->vp_length);
        }
 
        fr_tls_session_send(request, tls_session);
 
        return 1;
}
 
 
/*
 *      See if there's a TLV in the response.
 */
static int eap_peap_check_tlv(request_t *request, uint8_t const *data, size_t data_len)
{
        eap_packet_raw_t const *eap_packet = (eap_packet_raw_t const *) data;
 
        if (data_len < 11) return 0;
 
        /*
         *      Look for success or failure.
         */
        if ((eap_packet->code == FR_EAP_CODE_RESPONSE) &&
            (eap_packet->data[0] == FR_PEAP_EXTENSIONS_TYPE)) {
                if (data[10] == EAP_TLV_SUCCESS) {
                        return 1;
                }
 
                if (data[10] == EAP_TLV_FAILURE) {
                        RDEBUG2("Client rejected our response.  The password is probably incorrect");
                        return 0;
                }
        }
 
        RDEBUG2("Unknown TLV %02x", data[10]);
 
        return 0;
}
 
 
/*
 *      Use a reply packet to determine what to do.
 */
static rlm_rcode_t CC_HINT(nonnull) process_reply(eap_session_t *eap_session, fr_tls_session_t *tls_session,
                                                  request_t *request,
                                                  fr_packet_t *reply, fr_pair_list_t *reply_list)
{
        rlm_rcode_t rcode = RLM_MODULE_REJECT;
        fr_pair_list_t vps;
        peap_tunnel_t *t = tls_session->opaque;
 
        if (RDEBUG_ENABLED2) {
 
                /*
                 *      Note that we don't do *anything* with the reply
                 *      attributes.
                 */
                if (FR_RADIUS_PACKET_CODE_VALID(reply->code)) {
                        RDEBUG2("Got tunneled reply %s", fr_radius_packet_name[reply->code]);
                } else {
                        RDEBUG2("Got tunneled reply code %i", reply->code);
                }
                log_request_pair_list(L_DBG_LVL_2, request, NULL, reply_list, NULL);
        }
 
        switch (reply->code) {
        case FR_RADIUS_CODE_ACCESS_ACCEPT:
                RDEBUG2("Tunneled authentication was successful");
                t->status = PEAP_STATUS_SENT_TLV_SUCCESS;
                eap_peap_success(request, eap_session, tls_session);
                rcode = RLM_MODULE_HANDLED;
                break;
 
        case FR_RADIUS_CODE_ACCESS_REJECT:
                RDEBUG2("Tunneled authentication was rejected");
                t->status = PEAP_STATUS_SENT_TLV_FAILURE;
                eap_peap_failure(request, eap_session, tls_session);
                rcode = RLM_MODULE_HANDLED;
                break;
 
        case FR_RADIUS_CODE_ACCESS_CHALLENGE:
                RDEBUG2("Got tunneled Access-Challenge");
 
                /*
                 *      PEAP takes only EAP-Message attributes inside
                 *      of the tunnel.  Any Reply-Message in the
                 *      Access-Challenge is ignored.
                 */
                fr_pair_list_init(&vps);
                MEM(fr_pair_list_copy_by_da(t, &vps, reply_list, attr_eap_message, 0) >= 0);
 
                /*
                 *      Handle the ACK, by tunneling any necessary reply
                 *      VP's back to the client.
                 */
                if (!fr_pair_list_empty(&vps)) {
                        eap_peap_inner_from_pairs(request, tls_session, &vps);
                        fr_pair_list_free(&vps);
                }
 
                rcode = RLM_MODULE_HANDLED;
                break;
 
        default:
                RDEBUG2("Unknown RADIUS packet type %d: rejecting tunneled user", reply->code);
                rcode = RLM_MODULE_REJECT;
                break;
        }
 
        return rcode;
}
 
 
static char const *peap_state(peap_tunnel_t *t)
{
        switch (t->status) {
        case PEAP_STATUS_TUNNEL_ESTABLISHED:
                return "TUNNEL ESTABLISHED";
 
        case PEAP_STATUS_INNER_IDENTITY_REQ_SENT:
                return "WAITING FOR INNER IDENTITY";
 
        case PEAP_STATUS_SENT_TLV_SUCCESS:
                return "send tlv success";
 
        case PEAP_STATUS_SENT_TLV_FAILURE:
                return "send tlv failure";
 
        case PEAP_STATUS_PHASE2_INIT:
                return "phase2_init";
 
        case PEAP_STATUS_PHASE2:
                return "phase2";
 
        default:
                break;
        }
        return "?";
}
 
/*
 *      Process the pseudo-EAP contents of the tunneled data.
 */
unlang_action_t eap_peap_process(rlm_rcode_t *p_result, request_t *request,
                                 eap_session_t *eap_session, fr_tls_session_t *tls_session)
{
        peap_tunnel_t   *t = tls_session->opaque;
        request_t       *fake = NULL;
        fr_pair_t       *vp;
        rlm_rcode_t     rcode = RLM_MODULE_REJECT;
        uint8_t const   *data;
        size_t          data_len;
        eap_round_t     *eap_round = eap_session->this_round;
 
        /*
         *      Just look at the buffer directly, without doing
         *      record_to_buff.  This lets us avoid another data copy.
         */
        data_len = tls_session->clean_out.used;
        tls_session->clean_out.used = 0;
        data = tls_session->clean_out.data;
 
        RDEBUG2("PEAP state %s", peap_state(t));
 
        if ((t->status != PEAP_STATUS_TUNNEL_ESTABLISHED) && (eap_peap_verify(request, t, data, data_len) < 0)) {
                REDEBUG("Tunneled data is invalid");
                RETURN_MODULE_REJECT;
        }
 
        switch (t->status) {
        case PEAP_STATUS_TUNNEL_ESTABLISHED:
                /* FIXME: should be no data in the buffer here, check & assert? */
 
                if (SSL_session_reused(tls_session->ssl)) {
                        RDEBUG2("Skipping Phase2 because of session resumption");
                        t->session_resumption_state = PEAP_RESUMPTION_YES;
                        /* we're good, send success TLV */
                        t->status = PEAP_STATUS_SENT_TLV_SUCCESS;
                        eap_peap_success(request, eap_session, tls_session);
 
                } else {
                        /* send an identity request */
                        t->session_resumption_state = PEAP_RESUMPTION_NO;
                        t->status = PEAP_STATUS_INNER_IDENTITY_REQ_SENT;
                        eap_peap_identity(request, eap_session, tls_session);
                }
                rcode = RLM_MODULE_HANDLED;
                goto finish;
 
        case PEAP_STATUS_INNER_IDENTITY_REQ_SENT:
                /* we're expecting an identity response */
                if (data[0] != FR_EAP_METHOD_IDENTITY) {
                        REDEBUG("Expected EAP-Identity, got something else");
                        rcode = RLM_MODULE_REJECT;
                        goto finish;
                }
 
                /*
                 *      Save it for later.
                 */
                MEM(t->username = fr_pair_afrom_da(t, attr_user_name));
                t->username->vp_tainted = true;
 
                fr_pair_value_bstrndup(t->username, (char const *)data + 1, data_len - 1, true);
 
                RDEBUG2("Got inner identity \"%pV\"", &t->username->data);
                t->status = PEAP_STATUS_PHASE2_INIT;
                break;
 
        /*
         *      If we authenticated the user, then it's OK.
         */
        case PEAP_STATUS_SENT_TLV_SUCCESS:
                if (eap_peap_check_tlv(request, data, data_len)) {
                        RDEBUG2("Success");
                        rcode = RLM_MODULE_OK;
                        goto finish;
                }
 
                /*
                 *      Otherwise, the client rejected the session
                 *      resumption.  If the session is being re-used,
                 *      we need to do a full authentication.
                 *
                 *      We do this by sending an EAP-Identity request
                 *      inside of the PEAP tunnel.
                 */
                if (t->session_resumption_state == PEAP_RESUMPTION_YES) {
                        RDEBUG2("Client rejected session resumption.  Re-starting full authentication");
 
                        /*
                         *      Mark session resumption status.
                         */
                        t->status = PEAP_STATUS_INNER_IDENTITY_REQ_SENT;
                        t->session_resumption_state = PEAP_RESUMPTION_NO;
 
                        eap_peap_identity(request, eap_session, tls_session);
                        rcode = RLM_MODULE_HANDLED;
                        goto finish;
                }
 
                REDEBUG("Sent a success, but received something weird in return");
                rcode = RLM_MODULE_REJECT;
                goto finish;
 
        /*
         *      Supplicant ACKs our failure.
         */
        case PEAP_STATUS_SENT_TLV_FAILURE:
                RINDENT();
                REDEBUG("The users session was previously rejected: returning reject (again.)");
                RIDEBUG("This means you need to read the PREVIOUS messages in the debug output");
                RIDEBUG("to find out the reason why the user was rejected");
                RIDEBUG("Look for \"reject\" or \"fail\".  Those earlier messages will tell you");
                RIDEBUG("what went wrong, and how to fix the problem");
                REXDENT();
 
                RETURN_MODULE_REJECT;
 
                case PEAP_STATUS_PHASE2_INIT:
                        RDEBUG2("In state machine in phase2 init?");
                        break;
 
                case PEAP_STATUS_PHASE2:
                        break;
 
                default:
                        REDEBUG("Unhandled state in peap");
                        rcode = RLM_MODULE_REJECT;
                        goto finish;
        }
 
        fake = request_alloc_internal(request, &(request_init_args_t){ .parent = request });
        fr_assert(fr_pair_list_empty(&fake->request_pairs));
 
        switch (t->status) {
        /*
         *      If we're in PHASE2_INIT, the phase2 method hasn't been
         *      sent an Identity packet yet; do so from the stored
         *      username and this will kick off the phase2 eap method
         */
        case PEAP_STATUS_PHASE2_INIT:
        {
                size_t len;
                uint8_t *q;
 
                fr_assert(t->username);
 
                len = t->username->vp_length + EAP_HEADER_LEN + 1;
                t->status = PEAP_STATUS_PHASE2;
 
                MEM(vp = fr_pair_afrom_da(fake->request_ctx, attr_eap_message));
                MEM(fr_pair_value_mem_alloc(vp, &q, len, false) == 0);
                q[0] = FR_EAP_CODE_RESPONSE;
                q[1] = eap_round->response->id;
                q[2] = (len >> 8) & 0xff;
                q[3] = len & 0xff;
                q[4] = FR_EAP_METHOD_IDENTITY;
                memcpy(q + EAP_HEADER_LEN + 1,
                       t->username->vp_strvalue, t->username->vp_length);
                fr_pair_append(&fake->request_pairs, vp);
        }
                break;
 
        case PEAP_STATUS_PHASE2:
                eap_peap_inner_to_pairs(fake->request_ctx, &fake->request_pairs,
                                        eap_round, data, data_len);
                if (fr_pair_list_empty(&fake->request_pairs)) {
                        talloc_free(fake);
                        RDEBUG2("Unable to convert tunneled EAP packet to internal server data structures");
                        rcode = RLM_MODULE_REJECT;
                        goto finish;
                }
                break;
 
        default:
                REDEBUG("Invalid state change in PEAP");
                rcode = RLM_MODULE_REJECT;
                goto finish;
        }
 
        RDEBUG2("Got tunneled request");
        log_request_pair_list(L_DBG_LVL_2, request, NULL, &fake->request_pairs, NULL);
 
        /*
         *      Update other items in the request_t data structure.
         */
        if (!t->username) {
                /*
                 *      There's no User-Name in the tunneled session,
                 *      so we add one here, by pulling it out of the
                 *      EAP-Identity packet.
                 */
                if ((data[0] == FR_EAP_METHOD_IDENTITY) && (data_len > 1)) {
                        MEM(t->username = fr_pair_afrom_da(t, attr_user_name));
                        fr_assert(t->username != NULL);
                        t->username->vp_tainted = true;
 
                        fr_pair_value_bstrndup(t->username, (char const *)data + 1, data_len - 1, true);
 
                        RDEBUG2("Got tunneled identity of %pV", &t->username->data);
                }
        } /* else there WAS a t->username */
 
        setup_fake_request(request, fake, t);
 
        /*
         *      Call authentication recursively, which will
         *      do PAP, CHAP, MS-CHAP, etc.
         */
        eap_virtual_server(request, eap_session, t->virtual_server);
 
        /*
         *      Decide what to do with the reply.
         */
        if (!fake->reply->code) {
                REDEBUG("Unknown RADIUS packet type %d: rejecting tunneled user", fake->reply->code);
                rcode = RLM_MODULE_REJECT;
        } else {
                rcode = process_reply(eap_session, tls_session, request, fake->reply, &fake->reply_pairs);
        }
 
finish:
        talloc_free(fake);
 
        RETURN_MODULE_RCODE(rcode);
}
 
static int CC_HINT(nonnull) setup_fake_request(request_t *request, request_t *fake, peap_tunnel_t *t) {
 
        fr_pair_t *vp;
 
        /*
         *      Tell the request that it's a fake one.
         */
        MEM(fr_pair_prepend_by_da(fake->request_ctx, &vp, &fake->request_pairs, attr_freeradius_proxied_to) >= 0);
        (void) fr_pair_value_from_str(vp, "127.0.0.1", sizeof("127.0.0.1") - 1, NULL, false);
 
        if (t->username) {
                vp = fr_pair_copy(fake->request_ctx, t->username);
                fr_pair_append(&fake->request_pairs, vp);
                RDEBUG2("Setting &request.User-Name from tunneled (inner) identity \"%s\"",
                        vp->vp_strvalue);
        } else {
                RDEBUG2("No tunnel username (SSL resumption?)");
        }
 
        return 0;
}