eap_server_tnc.c

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/*
 * EAP server method: EAP-TNC (Trusted Network Connect)
 * Copyright (c) 2007-2010, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "base64.h"
#include "eap_i.h"
#include "tncs.h"


struct eap_tnc_data {
        enum eap_tnc_state {
                START, CONTINUE, RECOMMENDATION, FRAG_ACK, WAIT_FRAG_ACK, DONE,
                FAIL
        } state;
        enum { ALLOW, ISOLATE, NO_ACCESS, NO_RECOMMENDATION } recommendation;
        struct tncs_data *tncs;
        struct wpabuf *in_buf;
        struct wpabuf *out_buf;
        size_t out_used;
        size_t fragment_size;
        unsigned int was_done:1;
        unsigned int was_fail:1;
};


/* EAP-TNC Flags */
#define EAP_TNC_FLAGS_LENGTH_INCLUDED 0x80
#define EAP_TNC_FLAGS_MORE_FRAGMENTS 0x40
#define EAP_TNC_FLAGS_START 0x20
#define EAP_TNC_VERSION_MASK 0x07

#define EAP_TNC_VERSION 1


static const char * eap_tnc_state_txt(enum eap_tnc_state state)
{
        switch (state) {
        case START:
                return "START";
        case CONTINUE:
                return "CONTINUE";
        case RECOMMENDATION:
                return "RECOMMENDATION";
        case FRAG_ACK:
                return "FRAG_ACK";
        case WAIT_FRAG_ACK:
                return "WAIT_FRAG_ACK";
        case DONE:
                return "DONE";
        case FAIL:
                return "FAIL";
        }
        return "??";
}


static void eap_tnc_set_state(struct eap_tnc_data *data,
                              enum eap_tnc_state new_state)
{
        wpa_printf(MSG_DEBUG, "EAP-TNC: %s -> %s",
                   eap_tnc_state_txt(data->state),
                   eap_tnc_state_txt(new_state));
        data->state = new_state;
}


static void * eap_tnc_init(struct eap_sm *sm)
{
        struct eap_tnc_data *data;

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;
        eap_tnc_set_state(data, START);
        data->tncs = tncs_init();
        if (data->tncs == NULL) {
                os_free(data);
                return NULL;
        }

        data->fragment_size = 1300;

        return data;
}


static void eap_tnc_reset(struct eap_sm *sm, void *priv)
{
        struct eap_tnc_data *data = priv;
        wpabuf_free(data->in_buf);
        wpabuf_free(data->out_buf);
        tncs_deinit(data->tncs);
        os_free(data);
}


static struct wpabuf * eap_tnc_build_start(struct eap_sm *sm,
                                           struct eap_tnc_data *data, u8 id)
{
        struct wpabuf *req;

        req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 1, EAP_CODE_REQUEST,
                            id);
        if (req == NULL) {
                wpa_printf(MSG_ERROR, "EAP-TNC: Failed to allocate memory for "
                           "request");
                eap_tnc_set_state(data, FAIL);
                return NULL;
        }

        wpabuf_put_u8(req, EAP_TNC_FLAGS_START | EAP_TNC_VERSION);

        eap_tnc_set_state(data, CONTINUE);

        return req;
}


static struct wpabuf * eap_tnc_build(struct eap_sm *sm,
                                     struct eap_tnc_data *data)
{
        struct wpabuf *req;
        u8 *rpos, *rpos1;
        size_t rlen;
        char *start_buf, *end_buf;
        size_t start_len, end_len;
        size_t imv_len;

        imv_len = tncs_total_send_len(data->tncs);

        start_buf = tncs_if_tnccs_start(data->tncs);
        if (start_buf == NULL)
                return NULL;
        start_len = os_strlen(start_buf);
        end_buf = tncs_if_tnccs_end();
        if (end_buf == NULL) {
                os_free(start_buf);
                return NULL;
        }
        end_len = os_strlen(end_buf);

        rlen = start_len + imv_len + end_len;
        req = wpabuf_alloc(rlen);
        if (req == NULL) {
                os_free(start_buf);
                os_free(end_buf);
                return NULL;
        }

        wpabuf_put_data(req, start_buf, start_len);
        os_free(start_buf);

        rpos1 = wpabuf_put(req, 0);
        rpos = tncs_copy_send_buf(data->tncs, rpos1);
        wpabuf_put(req, rpos - rpos1);

        wpabuf_put_data(req, end_buf, end_len);
        os_free(end_buf);

        wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-TNC: Request",
                          wpabuf_head(req), wpabuf_len(req));

        return req;
}


static struct wpabuf * eap_tnc_build_recommendation(struct eap_sm *sm,
                                                    struct eap_tnc_data *data)
{
        switch (data->recommendation) {
        case ALLOW:
                eap_tnc_set_state(data, DONE);
                break;
        case ISOLATE:
                eap_tnc_set_state(data, FAIL);
                /* TODO: support assignment to a different VLAN */
                break;
        case NO_ACCESS:
                eap_tnc_set_state(data, FAIL);
                break;
        case NO_RECOMMENDATION:
                eap_tnc_set_state(data, DONE);
                break;
        default:
                wpa_printf(MSG_DEBUG, "EAP-TNC: Unknown recommendation");
                return NULL;
        }

        return eap_tnc_build(sm, data);
}


static struct wpabuf * eap_tnc_build_frag_ack(u8 id, u8 code)
{
        struct wpabuf *msg;

        msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 1, code, id);
        if (msg == NULL) {
                wpa_printf(MSG_ERROR, "EAP-TNC: Failed to allocate memory "
                           "for fragment ack");
                return NULL;
        }
        wpabuf_put_u8(msg, EAP_TNC_VERSION); /* Flags */

        wpa_printf(MSG_DEBUG, "EAP-TNC: Send fragment ack");

        return msg;
}


static struct wpabuf * eap_tnc_build_msg(struct eap_tnc_data *data, u8 id)
{
        struct wpabuf *req;
        u8 flags;
        size_t send_len, plen;

        wpa_printf(MSG_DEBUG, "EAP-TNC: Generating Request");

        flags = EAP_TNC_VERSION;
        send_len = wpabuf_len(data->out_buf) - data->out_used;
        if (1 + send_len > data->fragment_size) {
                send_len = data->fragment_size - 1;
                flags |= EAP_TNC_FLAGS_MORE_FRAGMENTS;
                if (data->out_used == 0) {
                        flags |= EAP_TNC_FLAGS_LENGTH_INCLUDED;
                        send_len -= 4;
                }
        }

        plen = 1 + send_len;
        if (flags & EAP_TNC_FLAGS_LENGTH_INCLUDED)
                plen += 4;
        req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, plen,
                            EAP_CODE_REQUEST, id);
        if (req == NULL)
                return NULL;

        wpabuf_put_u8(req, flags); /* Flags */
        if (flags & EAP_TNC_FLAGS_LENGTH_INCLUDED)
                wpabuf_put_be32(req, wpabuf_len(data->out_buf));

        wpabuf_put_data(req, wpabuf_head_u8(data->out_buf) + data->out_used,
                        send_len);
        data->out_used += send_len;

        if (data->out_used == wpabuf_len(data->out_buf)) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Sending out %lu bytes "
                           "(message sent completely)",
                           (unsigned long) send_len);
                wpabuf_free(data->out_buf);
                data->out_buf = NULL;
                data->out_used = 0;
                if (data->was_fail)
                        eap_tnc_set_state(data, FAIL);
                else if (data->was_done)
                        eap_tnc_set_state(data, DONE);
        } else {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Sending out %lu bytes "
                           "(%lu more to send)", (unsigned long) send_len,
                           (unsigned long) wpabuf_len(data->out_buf) -
                           data->out_used);
                if (data->state == FAIL)
                        data->was_fail = 1;
                else if (data->state == DONE)
                        data->was_done = 1;
                eap_tnc_set_state(data, WAIT_FRAG_ACK);
        }

        return req;
}


static struct wpabuf * eap_tnc_buildReq(struct eap_sm *sm, void *priv, u8 id)
{
        struct eap_tnc_data *data = priv;

        switch (data->state) {
        case START:
                tncs_init_connection(data->tncs);
                return eap_tnc_build_start(sm, data, id);
        case CONTINUE:
                if (data->out_buf == NULL) {
                        data->out_buf = eap_tnc_build(sm, data);
                        if (data->out_buf == NULL) {
                                wpa_printf(MSG_DEBUG, "EAP-TNC: Failed to "
                                           "generate message");
                                return NULL;
                        }
                        data->out_used = 0;
                }
                return eap_tnc_build_msg(data, id);
        case RECOMMENDATION:
                if (data->out_buf == NULL) {
                        data->out_buf = eap_tnc_build_recommendation(sm, data);
                        if (data->out_buf == NULL) {
                                wpa_printf(MSG_DEBUG, "EAP-TNC: Failed to "
                                           "generate recommendation message");
                                return NULL;
                        }
                        data->out_used = 0;
                }
                return eap_tnc_build_msg(data, id);
        case WAIT_FRAG_ACK:
                return eap_tnc_build_msg(data, id);
        case FRAG_ACK:
                return eap_tnc_build_frag_ack(id, EAP_CODE_REQUEST);
        case DONE:
        case FAIL:
                return NULL;
        }

        return NULL;
}


static Boolean eap_tnc_check(struct eap_sm *sm, void *priv,
                             struct wpabuf *respData)
{
        struct eap_tnc_data *data = priv;
        const u8 *pos;
        size_t len;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_TNC, respData,
                               &len);
        if (pos == NULL) {
                wpa_printf(MSG_INFO, "EAP-TNC: Invalid frame");
                return TRUE;
        }

        if (len == 0 && data->state != WAIT_FRAG_ACK) {
                wpa_printf(MSG_INFO, "EAP-TNC: Invalid frame (empty)");
                return TRUE;
        }

        if (len == 0)
                return FALSE; /* Fragment ACK does not include flags */

        if ((*pos & EAP_TNC_VERSION_MASK) != EAP_TNC_VERSION) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Unsupported version %d",
                           *pos & EAP_TNC_VERSION_MASK);
                return TRUE;
        }

        if (*pos & EAP_TNC_FLAGS_START) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Peer used Start flag");
                return TRUE;
        }

        return FALSE;
}


static void tncs_process(struct eap_tnc_data *data, struct wpabuf *inbuf)
{
        enum tncs_process_res res;

        res = tncs_process_if_tnccs(data->tncs, wpabuf_head(inbuf),
                                    wpabuf_len(inbuf));
        switch (res) {
        case TNCCS_RECOMMENDATION_ALLOW:
                wpa_printf(MSG_DEBUG, "EAP-TNC: TNCS allowed access");
                eap_tnc_set_state(data, RECOMMENDATION);
                data->recommendation = ALLOW;
                break;
        case TNCCS_RECOMMENDATION_NO_RECOMMENDATION:
                wpa_printf(MSG_DEBUG, "EAP-TNC: TNCS has no recommendation");
                eap_tnc_set_state(data, RECOMMENDATION);
                data->recommendation = NO_RECOMMENDATION;
                break;
        case TNCCS_RECOMMENDATION_ISOLATE:
                wpa_printf(MSG_DEBUG, "EAP-TNC: TNCS requested isolation");
                eap_tnc_set_state(data, RECOMMENDATION);
                data->recommendation = ISOLATE;
                break;
        case TNCCS_RECOMMENDATION_NO_ACCESS:
                wpa_printf(MSG_DEBUG, "EAP-TNC: TNCS rejected access");
                eap_tnc_set_state(data, RECOMMENDATION);
                data->recommendation = NO_ACCESS;
                break;
        case TNCCS_PROCESS_ERROR:
                wpa_printf(MSG_DEBUG, "EAP-TNC: TNCS processing error");
                eap_tnc_set_state(data, FAIL);
                break;
        default:
                break;
        }
}


static int eap_tnc_process_cont(struct eap_tnc_data *data,
                                const u8 *buf, size_t len)
{
        /* Process continuation of a pending message */
        if (len > wpabuf_tailroom(data->in_buf)) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Fragment overflow");
                eap_tnc_set_state(data, FAIL);
                return -1;
        }

        wpabuf_put_data(data->in_buf, buf, len);
        wpa_printf(MSG_DEBUG, "EAP-TNC: Received %lu bytes, waiting for %lu "
                   "bytes more", (unsigned long) len,
                   (unsigned long) wpabuf_tailroom(data->in_buf));

        return 0;
}


static int eap_tnc_process_fragment(struct eap_tnc_data *data,
                                    u8 flags, u32 message_length,
                                    const u8 *buf, size_t len)
{
        /* Process a fragment that is not the last one of the message */
        if (data->in_buf == NULL && !(flags & EAP_TNC_FLAGS_LENGTH_INCLUDED)) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: No Message Length field in a "
                           "fragmented packet");
                return -1;
        }

        if (data->in_buf == NULL) {
                /* First fragment of the message */
                data->in_buf = wpabuf_alloc(message_length);
                if (data->in_buf == NULL) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: No memory for "
                                   "message");
                        return -1;
                }
                wpabuf_put_data(data->in_buf, buf, len);
                wpa_printf(MSG_DEBUG, "EAP-TNC: Received %lu bytes in first "
                           "fragment, waiting for %lu bytes more",
                           (unsigned long) len,
                           (unsigned long) wpabuf_tailroom(data->in_buf));
        }

        return 0;
}


static void eap_tnc_process(struct eap_sm *sm, void *priv,
                            struct wpabuf *respData)
{
        struct eap_tnc_data *data = priv;
        const u8 *pos, *end;
        size_t len;
        u8 flags;
        u32 message_length = 0;
        struct wpabuf tmpbuf;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_TNC, respData, &len);
        if (pos == NULL)
                return; /* Should not happen; message already verified */

        end = pos + len;

        if (len == 1 && (data->state == DONE || data->state == FAIL)) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Peer acknowledged the last "
                           "message");
                return;
        }

        if (len == 0) {
                /* fragment ack */
                flags = 0;
        } else
                flags = *pos++;

        if (flags & EAP_TNC_FLAGS_LENGTH_INCLUDED) {
                if (end - pos < 4) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: Message underflow");
                        eap_tnc_set_state(data, FAIL);
                        return;
                }
                message_length = WPA_GET_BE32(pos);
                pos += 4;

                if (message_length < (u32) (end - pos)) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: Invalid Message "
                                   "Length (%d; %ld remaining in this msg)",
                                   message_length, (long) (end - pos));
                        eap_tnc_set_state(data, FAIL);
                        return;
                }
        }
        wpa_printf(MSG_DEBUG, "EAP-TNC: Received packet: Flags 0x%x "
                   "Message Length %u", flags, message_length);

        if (data->state == WAIT_FRAG_ACK) {
                if (len > 1) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: Unexpected payload "
                                   "in WAIT_FRAG_ACK state");
                        eap_tnc_set_state(data, FAIL);
                        return;
                }
                wpa_printf(MSG_DEBUG, "EAP-TNC: Fragment acknowledged");
                eap_tnc_set_state(data, CONTINUE);
                return;
        }

        if (data->in_buf && eap_tnc_process_cont(data, pos, end - pos) < 0) {
                eap_tnc_set_state(data, FAIL);
                return;
        }
                
        if (flags & EAP_TNC_FLAGS_MORE_FRAGMENTS) {
                if (eap_tnc_process_fragment(data, flags, message_length,
                                             pos, end - pos) < 0)
                        eap_tnc_set_state(data, FAIL);
                else
                        eap_tnc_set_state(data, FRAG_ACK);
                return;
        } else if (data->state == FRAG_ACK) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: All fragments received");
                eap_tnc_set_state(data, CONTINUE);
        }

        if (data->in_buf == NULL) {
                /* Wrap unfragmented messages as wpabuf without extra copy */
                wpabuf_set(&tmpbuf, pos, end - pos);
                data->in_buf = &tmpbuf;
        }

        wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-TNC: Received payload",
                          wpabuf_head(data->in_buf), wpabuf_len(data->in_buf));
        tncs_process(data, data->in_buf);

        if (data->in_buf != &tmpbuf)
                wpabuf_free(data->in_buf);
        data->in_buf = NULL;
}


static Boolean eap_tnc_isDone(struct eap_sm *sm, void *priv)
{
        struct eap_tnc_data *data = priv;
        return data->state == DONE || data->state == FAIL;
}


static Boolean eap_tnc_isSuccess(struct eap_sm *sm, void *priv)
{
        struct eap_tnc_data *data = priv;
        return data->state == DONE;
}


int eap_server_tnc_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
                                      EAP_VENDOR_IETF, EAP_TYPE_TNC, "TNC");
        if (eap == NULL)
                return -1;

        eap->init = eap_tnc_init;
        eap->reset = eap_tnc_reset;
        eap->buildReq = eap_tnc_buildReq;
        eap->check = eap_tnc_check;
        eap->process = eap_tnc_process;
        eap->isDone = eap_tnc_isDone;
        eap->isSuccess = eap_tnc_isSuccess;

        ret = eap_server_method_register(eap);
        if (ret)
                eap_server_method_free(eap);
        return ret;
}