ttls.c

Go to the documentation of this file.

/*
 *   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: bd03c3da7b326b618cc5b029422639659d2c33e4 $
 * @file ttls.c
 * @brief Library functions for EAP-TTLS as defined by RFC 5281
 *
 * @copyright 2003 Alan DeKok (aland@freeradius.org)
 * @copyright 2006 The FreeRADIUS server project
 */
 
RCSID("$Id: bd03c3da7b326b618cc5b029422639659d2c33e4 $")
 
#include <freeradius-devel/eap/chbind.h>
#include <freeradius-devel/tls/log.h>
#include <freeradius-devel/tls/strerror.h>
#include "eap_ttls.h"
 
#define FR_DIAMETER_AVP_FLAG_VENDOR     0x80
#define FR_DIAMETER_AVP_FLAG_MANDATORY  0x40
/*
 *    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
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                           AVP Code                            |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |V M r r r r r r|                  AVP Length                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                        Vendor-ID (opt)                        |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Data ...
 *   +-+-+-+-+-+-+-+-+
 */
 
/*
 *      Verify that the diameter packet is valid.
 */
static int diameter_verify(request_t *request, uint8_t const *data, unsigned int data_len)
{
        uint32_t attr;
        uint32_t length;
        unsigned int hdr_len;
        unsigned int remaining = data_len;
 
        while (remaining > 0) {
                hdr_len = 12;
 
                if (remaining < hdr_len) {
                  RDEBUG2("Diameter attribute is too small (%u) to contain a Diameter header", remaining);
                        return 0;
                }
 
                memcpy(&attr, data, sizeof(attr));
                attr = ntohl(attr);
                memcpy(&length, data + 4, sizeof(length));
                length = ntohl(length);
 
                if ((data[4] & 0x80) != 0) {
                        if (remaining < 16) {
                                RDEBUG2("Diameter attribute is too small to contain a Diameter header with Vendor-Id");
                                return 0;
                        }
 
                        hdr_len = 16;
                }
 
                /*
                 *      Get the length.  If it's too big, die.
                 */
                length &= 0x00ffffff;
 
                /*
                 *      Too short or too long is bad.
                 */
                if (length <= (hdr_len - 4)) {
                        RDEBUG2("Tunneled attribute %u is too short (%u < %u) to contain anything useful.", attr,
                                length, hdr_len);
                        return 0;
                }
 
                if (length > remaining) {
                        RDEBUG2("Tunneled attribute %u is longer than room remaining in the packet (%u > %u).", attr,
                                length, remaining);
                        return 0;
                }
 
                /*
                 *      Check for broken implementations, which don't
                 *      pad the AVP to a 4-octet boundary.
                 */
                if (remaining == length) break;
 
                /*
                 *      The length does NOT include the padding, so
                 *      we've got to account for it here by rounding up
                 *      to the nearest 4-byte boundary.
                 */
                length += 0x03;
                length &= ~0x03;
 
                /*
                 *      If the rest of the diameter packet is larger than
                 *      this attribute, continue.
                 *
                 *      Otherwise, if the attribute over-flows the end
                 *      of the packet, die.
                 */
                if (remaining < length) {
                        REDEBUG2("Diameter attribute overflows packet!");
                        return 0;
                }
 
                /*
                 *      remaining > length, continue.
                 */
                remaining -= length;
                data += length;
        }
 
        /*
         *      We got this far.  It looks OK.
         */
        return 1;
}
 
 
/*
 *      Convert diameter attributes to our fr_pair_t's
 */
static ssize_t eap_ttls_decode_pair(request_t *request, TALLOC_CTX *ctx, fr_pair_list_t *out,
                                    fr_dict_attr_t const *parent,
                                    uint8_t const *data, size_t data_len,
                                    void *decode_ctx)
{
        uint8_t const           *p = data, *end = p + data_len;
 
        fr_pair_t               *vp = NULL;
        SSL                     *ssl = decode_ctx;
        fr_dict_t const         *dict_radius;
        fr_dict_attr_t const    *attr_radius;
        fr_dict_attr_t const    *da;
        TALLOC_CTX              *tmp_ctx = NULL;
 
        dict_radius = fr_dict_by_protocol_name("radius");
        fr_assert(dict_radius != NULL);
        attr_radius = fr_dict_root(dict_radius);
 
        while (p < end) {
                ssize_t                 ret;
                uint32_t                attr, vendor;
                uint64_t                value_len;
                uint8_t                 flags;
                fr_dict_attr_t const    *our_parent = parent;
 
                if ((end - p) < 8) {
                        fr_strerror_printf("Malformed diameter attribute at offset %zu.  Needed at least 8 bytes, got %zu bytes",
                                           p - data, end - p);
                error:
                        talloc_free(tmp_ctx);
                        fr_pair_list_free(out);
                        return -1;
                }
 
                RDEBUG3("%04zu %02x%02x%02x%02x %02x%02x%02x%02x ...", p - data,
                        p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
 
                attr = fr_nbo_to_uint32(p);
                p += 4;
 
                flags = p[0];
                p++;
 
                value_len = fr_nbo_to_uint64v(p, 3);    /* Yes, that is a 24 bit length field */
                p += 3;
 
                if (value_len < 8) {
                        fr_strerror_printf("Malformed diameter attribute at offset %zu.  Needed at least length of 8, got %u",
                                           p - data, (unsigned int) value_len);
                        goto error;
                }
 
                /*
                 *      Account for the 8 bytes we've already read from the packet.
                 */
                if ((p + ((value_len + 0x03) & ~0x03)) - 8 > end) {
                        fr_strerror_printf("Malformed diameter attribute at offset %zu.  Value length %u overflows input",
                                           p - data, (unsigned int) value_len);
                        goto error;
                }
 
                value_len -= 8; /* -= 8 for AVP code (4), flags (1), AVP length (3) */
 
                /*
                 *      Do we have a vendor field?
                 */
                if (flags & FR_DIAMETER_AVP_FLAG_VENDOR) {
                        vendor = fr_nbo_to_uint32(p);
                        p += 4;
                        value_len -= 4; /* -= 4 for the vendor ID field */
 
                        our_parent = fr_dict_vendor_da_by_num(attr_vendor_specific, vendor);
                        if (!our_parent) {
                                if (flags & FR_DIAMETER_AVP_FLAG_MANDATORY) {
                                        fr_strerror_printf("Mandatory bit set and no vendor %u found", vendor);
                                        goto error;
                                }
 
                                if (!tmp_ctx) {
                                        fr_dict_attr_t *n;
 
                                        MEM(our_parent = n = fr_dict_attr_unknown_vendor_afrom_num(ctx, parent, vendor));
                                        tmp_ctx = n;
                                } else {
                                        MEM(our_parent = fr_dict_attr_unknown_vendor_afrom_num(tmp_ctx, parent, vendor));
                                }
                        }
                } else {
                        our_parent = attr_radius;
                }
 
                /*
                 *      Is the attribute known?
                 */
                da = fr_dict_attr_child_by_num(our_parent, attr);
                if (!da) {
                        if (flags & FR_DIAMETER_AVP_FLAG_MANDATORY) {
                                fr_strerror_printf("Mandatory bit set and no attribute %u defined for parent %s", attr, parent->name);
                                goto error;
                        }
 
                        MEM(da = fr_dict_attr_unknown_raw_afrom_num(vp, our_parent, attr));
                }
 
                MEM(vp =fr_pair_afrom_da_nested(ctx, out, da));
 
                ret = fr_value_box_from_network(vp, &vp->data, vp->vp_type, vp->da,
                                                &FR_DBUFF_TMP(p, (size_t)value_len), value_len, true);
                if (ret < 0) {
                        /*
                         *      Mandatory bit is set, and the attribute
                         *      is malformed. Fail.
                         */
                        if (flags & FR_DIAMETER_AVP_FLAG_MANDATORY) {
                                fr_strerror_const("Mandatory bit is set and attribute is malformed");
                                goto error;
                        }
 
                        fr_pair_raw_afrom_pair(vp, p, value_len);
                }
 
                /*
                 *      The length does NOT include the padding, so
                 *      we've got to account for it here by rounding up
                 *      to the nearest 4-byte boundary.
                 */
                p += (value_len + 0x03) & ~0x03;
 
                if (vp->da->flags.is_unknown) continue;
 
                /*
                 *      Ensure that the client is using the correct challenge.
                 *
                 *      This weirdness is to protect against against replay
                 *      attacks, where anyone observing the CHAP exchange could
                 *      pose as that user, by simply choosing to use the same
                 *      challenge.
                 *      By using a challenge based on information from the
                 *      current session, we can guarantee that the client is
                 *      not *choosing* a challenge. We're a little forgiving in
                 *      that we have loose checks on the length, and we do NOT
                 *      check the Id (first octet of the response to the
                 *      challenge) But if the client gets the challenge correct,
                 *      we're not too worried about the Id.
                 */
                if ((vp->da == attr_chap_challenge) || (vp->da == attr_ms_chap_challenge)) {
                        uint8_t challenge[17];
                        static const char label[] = "ttls challenge";
 
                        if ((vp->vp_length < 8) || (vp->vp_length > 16)) {
                                fr_strerror_const("Tunneled challenge has invalid length");
                                goto error;
                        }
 
                        /*
                         *      TLSv1.3 exports a different key depending on the length
                         *      requested so ask for *exactly* what the spec requires
                         */
                        if (SSL_export_keying_material(ssl, challenge, vp->vp_length + 1,
                                                       label, sizeof(label) - 1, NULL, 0, 0) != 1) {
                                fr_tls_strerror_printf("Failed generating phase2 challenge");
                                goto error;
                        }
 
                        if (memcmp(challenge, vp->vp_octets, vp->vp_length) != 0) {
                                fr_strerror_const("Tunneled challenge is incorrect");
                                goto error;
                        }
                }
 
                /*
                 *      Diameter pads strings (i.e. User-Password) with trailing zeros.
                 */
                if (vp->vp_type == FR_TYPE_STRING) fr_pair_value_strtrim(vp);
        }
 
        /*
         *      We got this far.  It looks OK.
         */
        talloc_free(tmp_ctx);
        return p - data;
}
 
/*
 *      Convert fr_pair_t's to diameter attributes, and write them
 *      to an SSL session.
 *
 *      The ONLY fr_pair_t's which may be passed to this function
 *      are ones which can go inside of a RADIUS (i.e. diameter)
 *      packet.  So no server-configuration attributes, or the like.
 */
static int vp2diameter(request_t *request, fr_tls_session_t *tls_session, fr_pair_list_t *list)
{
        /*
         *      RADIUS packets are no more than 4k in size, so if
         *      we've got more than 4k of data to write, it's very
         *      bad.
         */
        uint8_t         buffer[4096];
        uint8_t         *p;
        uint32_t        attr;
        uint32_t        length;
        uint32_t        vendor;
        size_t          total;
        uint64_t        attr64;
        fr_pair_t       *vp;
 
        p = buffer;
        total = 0;
 
        for (vp = fr_pair_list_head(list);
             vp;
             vp = fr_pair_list_next(list, vp)) {
                /*
                 *      Too much data: die.
                 */
                if ((total + vp->vp_length + 12) >= sizeof(buffer)) {
                        RDEBUG2("output buffer is full!");
                        return 0;
                }
 
                /*
                 *      Hmm... we don't group multiple EAP-Messages
                 *      together.  Maybe we should...
                 */
 
                length = vp->vp_length;
                vendor = fr_dict_vendor_num_by_da(vp->da);
                if (vendor != 0) {
                        attr = vp->da->attr & 0xffff;
                        length |= ((uint32_t)1 << 31);
                } else {
                        attr = vp->da->attr;
                }
 
                /*
                 *      Hmm... set the M bit for all attributes?
                 */
                length |= (1 << 30);
 
                attr = ntohl(attr);
 
                memcpy(p, &attr, sizeof(attr));
                p += 4;
                total += 4;
 
                length += 8;    /* includes 8 bytes of attr & length */
 
                if (vendor != 0) {
                        length += 4; /* include 4 bytes of vendor */
 
                        length = ntohl(length);
                        memcpy(p, &length, sizeof(length));
                        p += 4;
                        total += 4;
 
                        vendor = ntohl(vendor);
                        memcpy(p, &vendor, sizeof(vendor));
                        p += 4;
                        total += 4;
                } else {
                        length = ntohl(length);
                        memcpy(p, &length, sizeof(length));
                        p += 4;
                        total += 4;
                }
 
                switch (vp->vp_type) {
                case FR_TYPE_DATE:
                        attr = htonl(fr_unix_time_to_sec(vp->vp_date)); /* stored in host order */
                        memcpy(p, &attr, sizeof(attr));
                        length = 4;
                        break;
 
                case FR_TYPE_UINT32:
                        attr = htonl(vp->vp_uint32); /* stored in host order */
                        memcpy(p, &attr, sizeof(attr));
                        length = 4;
                        break;
 
                case FR_TYPE_UINT64:
                        attr64 = htonll(vp->vp_uint64); /* stored in host order */
                        memcpy(p, &attr64, sizeof(attr64));
                        length = 8;
                        break;
 
                case FR_TYPE_IPV4_ADDR:
                        memcpy(p, &vp->vp_ipv4addr, 4); /* network order */
                        length = 4;
                        break;
 
                case FR_TYPE_STRING:
                case FR_TYPE_OCTETS:
                default:
                        memcpy(p, vp->vp_strvalue, vp->vp_length);
                        length = vp->vp_length;
                        break;
                }
 
                /*
                 *      Skip to the end of the data.
                 */
                p += length;
                total += length;
 
                /*
                 *      Align the data to a multiple of 4 bytes.
                 */
                if ((total & 0x03) != 0) {
                        size_t i;
 
                        length = 4 - (total & 0x03);
                        for (i = 0; i < length; i++) {
                                *p = '\0';
                                p++;
                                total++;
                        }
                }
        } /* loop over the VP's to write. */
 
        /*
         *      Write the data in the buffer to the SSL session.
         */
        if (total > 0) {
                (tls_session->record_from_buff)(&tls_session->clean_in, buffer, total);
 
                /*
                 *      FIXME: Check the return code.
                 */
                fr_tls_session_send(request, tls_session);
        }
 
        /*
         *      Everything's OK.
         */
        return 1;
}
 
/*
 *      Use a reply packet to determine what to do.
 */
static unlang_action_t process_reply(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        eap_session_t           *eap_session = talloc_get_type_abort(mctx->rctx, eap_session_t);
        eap_tls_session_t       *eap_tls_session = talloc_get_type_abort(eap_session->opaque, eap_tls_session_t);
        fr_tls_session_t        *tls_session = eap_tls_session->tls_session;
        fr_pair_t               *vp = NULL;
        fr_pair_list_t          tunnel_vps;
        ttls_tunnel_t           *t = tls_session->opaque;
        fr_packet_t             *reply = request->reply;
 
        fr_pair_list_init(&tunnel_vps);
        fr_assert(eap_session->request == request->parent);
 
        /*
         *      If the response packet was Access-Accept, then
         *      we're OK.  If not, die horribly.
         *
         *      FIXME: Take MS-CHAP2-Success attribute, and
         *      tunnel it back to the client, to authenticate
         *      ourselves to the client.
         *
         *      FIXME: If we have an Access-Challenge, then
         *      the Reply-Message is tunneled back to the client.
         *
         *      FIXME: If we have an EAP-Message, then that message
         *      must be tunneled back to the client.
         *
         *      FIXME: If we have an Access-Challenge with a State
         *      attribute, then do we tunnel that to the client, or
         *      keep track of it ourselves?
         *
         *      FIXME: EAP-Messages can only start with 'identity',
         *      NOT 'eap start', so we should check for that....
         */
        switch (reply->code) {
        case FR_RADIUS_CODE_ACCESS_ACCEPT:
                RDEBUG2("Got tunneled Access-Accept");
 
                /*
                 *      Copy what we need into the TTLS tunnel and leave
                 *      the rest to be cleaned up.
                 */
                if ((vp = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_ms_chap2_success))) {
                        RDEBUG2("Got MS-CHAP2-Success, tunneling it to the client in a challenge");
                } else {
                        vp = fr_pair_find_by_da_nested(&request->reply_pairs, NULL, attr_eap_channel_binding_message);
                }
                if (vp) {
                        t->authenticated = true;
                        fr_pair_prepend(&tunnel_vps, fr_pair_copy(tls_session, vp));
                        reply->code = FR_RADIUS_CODE_ACCESS_CHALLENGE;
                        break;
                }
 
                /*
                 *      Success: Automatically return MPPE keys.
                 */
                return eap_ttls_success(p_result, request, eap_session);
 
        case FR_RADIUS_CODE_ACCESS_REJECT:
                REDEBUG("Got tunneled Access-Reject");
                eap_tls_fail(request, eap_session);
                RETURN_MODULE_REJECT;
 
        /*
         *      Handle Access-Challenge, but only if we
         *      send tunneled reply data.  This is because
         *      an Access-Challenge means that we MUST tunnel
         *      a Reply-Message to the client.
         */
        case FR_RADIUS_CODE_ACCESS_CHALLENGE:
                RDEBUG2("Got tunneled Access-Challenge");
 
                /*
                 *      Copy what we need into the TTLS tunnel and leave
                 *      the rest to be cleaned up.
                 */
                vp = NULL;
                while ((vp = fr_pair_list_next(&request->reply_pairs, vp))) {
                        if ((vp->da == attr_eap_message) || (vp->da == attr_reply_message)) {
                                fr_pair_prepend(&tunnel_vps, fr_pair_copy(tls_session, vp));
                        } else if (vp->da == attr_eap_channel_binding_message) {
                                fr_pair_prepend(&tunnel_vps, fr_pair_copy(tls_session, vp));
                        }
                }
                break;
 
        default:
                REDEBUG("Unknown RADIUS packet type %d: rejecting tunneled user", reply->code);
                eap_tls_fail(request, eap_session);
                RETURN_MODULE_INVALID;
        }
 
 
        /*
         *      Pack any tunneled VPs and send them back
         *      to the supplicant.
         */
        if (!fr_pair_list_empty(&tunnel_vps)) {
                RDEBUG2("Sending tunneled reply attributes");
                log_request_pair_list(L_DBG_LVL_2, request, NULL, &tunnel_vps, NULL);
 
                vp2diameter(request, tls_session, &tunnel_vps);
                fr_pair_list_free(&tunnel_vps);
        }
 
        eap_tls_request(request, eap_session);
        RETURN_MODULE_OK;
}
 
unlang_action_t eap_ttls_success(rlm_rcode_t *p_result, request_t *request, eap_session_t *eap_session)
{
        eap_tls_session_t       *eap_tls_session = talloc_get_type_abort(eap_session->opaque, eap_tls_session_t);
        fr_tls_session_t        *tls_session = eap_tls_session->tls_session;
        eap_tls_prf_label_t prf_label;
 
        eap_crypto_prf_label_init(&prf_label, eap_session,
                                  "ttls keying material",
                                  sizeof("ttls keying material") - 1);
        /*
         *      Success: Automatically return MPPE keys.
         */
        if (eap_tls_success(request, eap_session, &prf_label) < 0) RETURN_MODULE_FAIL;
 
        /*
         *      Result is always OK, even if we fail to persist the
         *      session data.
         */
        *p_result = RLM_MODULE_OK;
 
        /*
         *      Write the session to the session cache
         *
         *      We do this here (instead of relying on OpenSSL to call the
         *      session caching callback), because we only want to write
         *      session data to the cache if all phases were successful.
         *
         *      If we wrote out the cache data earlier, and the server
         *      exited whilst the session was in progress, the supplicant
         *      could resume the session (and get access) even if phase2
         *      never completed.
         */
        return fr_tls_cache_pending_push(request, tls_session);
}
 
 
/*
 *      Process the "diameter" contents of the tunneled data.
 */
unlang_action_t eap_ttls_process(request_t *request, eap_session_t *eap_session, fr_tls_session_t *tls_session)
{
        fr_pair_t               *vp = NULL;
        ttls_tunnel_t           *t;
        uint8_t                 const *data;
        size_t                  data_len;
        chbind_packet_t         *chbind;
        fr_pair_t               *username;
 
        /*
         *      Just look at the buffer directly, without doing
         *      record_to_buff.
         */
        data_len = tls_session->clean_out.used;
        tls_session->clean_out.used = 0;
        data = tls_session->clean_out.data;
 
        t = (ttls_tunnel_t *) tls_session->opaque;
 
        /*
         *      If there's no data, maybe this is an ACK to an
         *      MS-CHAP2-Success.
         */
        if (data_len == 0) {
                if (t->authenticated) {
                        RDEBUG2("Got ACK, and the user was already authenticated");
                        return eap_ttls_success(&request->rcode, request, eap_session);
                } /* else no session, no data, die. */
 
                /*
                 *      FIXME: Call SSL_get_error() to see what went
                 *      wrong.
                 */
                RDEBUG2("SSL_read Error");
                return UNLANG_ACTION_FAIL;
        }
 
        if (!diameter_verify(request, data, data_len)) return UNLANG_ACTION_FAIL;
 
        /*
         *      Add the tunneled attributes to the request request.
         */
        if (eap_ttls_decode_pair(request, request->request_ctx, &request->request_pairs, fr_dict_root(fr_dict_internal()),
                                 data, data_len, tls_session->ssl) < 0) {
                RPEDEBUG("Decoding TTLS TLVs failed");
                return UNLANG_ACTION_FAIL;
        }
 
        /*
         *      Update other items in the request_t data structure.
         */
 
        /*
         *      No User-Name, try to create one from stored data.
         */
        username = fr_pair_find_by_da(&request->request_pairs, NULL, attr_user_name);
        if (!username) {
                /*
                 *      No User-Name in the stored data, look for
                 *      an EAP-Identity, and pull it out of there.
                 */
                if (!t->username) {
                        vp = fr_pair_find_by_da(&request->request_pairs, NULL, attr_eap_message);
                        if (vp &&
                            (vp->vp_length >= EAP_HEADER_LEN + 2) &&
                            (vp->vp_strvalue[0] == FR_EAP_CODE_RESPONSE) &&
                            (vp->vp_strvalue[EAP_HEADER_LEN] == FR_EAP_METHOD_IDENTITY) &&
                            (vp->vp_strvalue[EAP_HEADER_LEN + 1] != 0)) {
                                /*
                                 *      Create & remember a User-Name
                                 */
                                MEM(t->username = fr_pair_afrom_da(t, attr_user_name));
                                t->username->vp_tainted = true;
 
                                fr_pair_value_bstrndup(t->username,
                                                       (char const *)vp->vp_octets + 5, vp->vp_length - 5, true);
 
                                RDEBUG2("Got tunneled identity of %pV", &t->username->data);
                        } else {
                                /*
                                 *      Don't reject the request outright,
                                 *      as it's permitted to do EAP without
                                 *      user-name.
                                 */
                                RWDEBUG2("No EAP-Identity found to start EAP conversation");
                        }
                } /* else there WAS a t->username */
 
                if (t->username) {
                        vp = fr_pair_copy(request->request_ctx, t->username);
                        fr_pair_append(&request->request_pairs, vp);
                }
        } /* else the request ALREADY had a User-Name */
 
        /*
         *      Process channel binding.
         */
        chbind = eap_chbind_vp2packet(request, &request->request_pairs);
        if (chbind) {
                fr_radius_packet_code_t chbind_code;
                CHBIND_REQ *req = talloc_zero(request, CHBIND_REQ);
 
                RDEBUG2("received chbind request");
                req->request = chbind;
                if (username) {
                        req->username = username;
                } else {
                        req->username = NULL;
                }
                chbind_code = chbind_process(request, req);
 
                /* encapsulate response here */
                if (req->response) {
                        RDEBUG2("sending chbind response");
                        fr_pair_append(&request->reply_pairs,
                                    eap_chbind_packet2vp(request->reply_ctx, req->response));
                } else {
                        RDEBUG2("no chbind response");
                }
 
                /* clean up chbind req */
                talloc_free(req);
 
                if (chbind_code != FR_RADIUS_CODE_ACCESS_ACCEPT) return UNLANG_ACTION_FAIL;
        }
 
        (void) unlang_module_yield(request, process_reply, NULL, 0, eap_session);
        /*
         *      Call authentication recursively, which will
         *      do PAP, CHAP, MS-CHAP, etc.
         */
        return eap_virtual_server(request, eap_session, t->server_cs);
}