eap_tnc.c

Go to the documentation of this file.

/*
 * EAP peer method: EAP-TNC (Trusted Network Connect)
 * Copyright (c) 2007, 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 "tncc.h"


struct eap_tnc_data {
        enum { WAIT_START, PROC_MSG, WAIT_FRAG_ACK, DONE, FAIL } state;
        struct tncc_data *tncc;
        struct wpabuf *in_buf;
        struct wpabuf *out_buf;
        size_t out_used;
        size_t fragment_size;
};


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

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;
        data->state = WAIT_START;
        data->fragment_size = 1300;
        data->tncc = tncc_init();
        if (data->tncc == NULL) {
                os_free(data);
                return NULL;
        }

        return data;
}


static void eap_tnc_deinit(struct eap_sm *sm, void *priv)
{
        struct eap_tnc_data *data = priv;

        wpabuf_free(data->in_buf);
        wpabuf_free(data->out_buf);
        tncc_deinit(data->tncc);
        os_free(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,
                                         struct eap_method_ret *ret, u8 id)
{
        struct wpabuf *resp;
        u8 flags;
        size_t send_len, plen;

        ret->ignore = FALSE;
        wpa_printf(MSG_DEBUG, "EAP-TNC: Generating Response");
        ret->allowNotifications = TRUE;

        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;
        resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, plen,
                             EAP_CODE_RESPONSE, id);
        if (resp == NULL)
                return NULL;

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

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

        ret->methodState = METHOD_MAY_CONT;
        ret->decision = DECISION_FAIL;

        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;
        } 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);
                data->state = WAIT_FRAG_ACK;
        }

        return resp;
}


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");
                data->state = 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 struct wpabuf * eap_tnc_process_fragment(struct eap_tnc_data *data,
                                                struct eap_method_ret *ret,
                                                u8 id, 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");
                ret->ignore = TRUE;
                return NULL;
        }

        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");
                        ret->ignore = TRUE;
                        return NULL;
                }
                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 eap_tnc_build_frag_ack(id, EAP_CODE_RESPONSE);
}


static struct wpabuf * eap_tnc_process(struct eap_sm *sm, void *priv,
                                       struct eap_method_ret *ret,
                                       const struct wpabuf *reqData)
{
        struct eap_tnc_data *data = priv;
        struct wpabuf *resp;
        const u8 *pos, *end;
        u8 *rpos, *rpos1;
        size_t len, rlen;
        size_t imc_len;
        char *start_buf, *end_buf;
        size_t start_len, end_len;
        int tncs_done = 0;
        u8 flags, id;
        u32 message_length = 0;
        struct wpabuf tmpbuf;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_TNC, reqData, &len);
        if (pos == NULL) {
                wpa_printf(MSG_INFO, "EAP-TNC: Invalid frame (pos=%p len=%lu)",
                           pos, (unsigned long) len);
                ret->ignore = TRUE;
                return NULL;
        }

        id = eap_get_id(reqData);

        end = pos + len;

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

        if (len > 0 && (flags & EAP_TNC_VERSION_MASK) != EAP_TNC_VERSION) {
                wpa_printf(MSG_DEBUG, "EAP-TNC: Unsupported version %d",
                           flags & EAP_TNC_VERSION_MASK);
                ret->ignore = TRUE;
                return NULL;
        }

        if (flags & EAP_TNC_FLAGS_LENGTH_INCLUDED) {
                if (end - pos < 4) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: Message underflow");
                        ret->ignore = TRUE;
                        return NULL;
                }
                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));
                        ret->ignore = TRUE;
                        return NULL;
                }
        }

        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");
                        ret->ignore = TRUE;
                        return NULL;
                }
                wpa_printf(MSG_DEBUG, "EAP-TNC: Fragment acknowledged");
                data->state = PROC_MSG;
                return eap_tnc_build_msg(data, ret, id);
        }

        if (data->in_buf && eap_tnc_process_cont(data, pos, end - pos) < 0) {
                ret->ignore = TRUE;
                return NULL;
        }
                
        if (flags & EAP_TNC_FLAGS_MORE_FRAGMENTS) {
                return eap_tnc_process_fragment(data, ret, id, flags,
                                                message_length, pos,
                                                end - pos);
        }

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

        if (data->state == WAIT_START) {
                if (!(flags & EAP_TNC_FLAGS_START)) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: Server did not use "
                                   "start flag in the first message");
                        ret->ignore = TRUE;
                        goto fail;
                }

                tncc_init_connection(data->tncc);

                data->state = PROC_MSG;
        } else {
                enum tncc_process_res res;

                if (flags & EAP_TNC_FLAGS_START) {
                        wpa_printf(MSG_DEBUG, "EAP-TNC: Server used start "
                                   "flag again");
                        ret->ignore = TRUE;
                        goto fail;
                }

                res = tncc_process_if_tnccs(data->tncc,
                                            wpabuf_head(data->in_buf),
                                            wpabuf_len(data->in_buf));
                switch (res) {
                case TNCCS_PROCESS_ERROR:
                        ret->ignore = TRUE;
                        goto fail;
                case TNCCS_PROCESS_OK_NO_RECOMMENDATION:
                case TNCCS_RECOMMENDATION_ERROR:
                        wpa_printf(MSG_DEBUG, "EAP-TNC: No "
                                   "TNCCS-Recommendation received");
                        break;
                case TNCCS_RECOMMENDATION_ALLOW:
                        wpa_msg(sm->msg_ctx, MSG_INFO,
                                "TNC: Recommendation = allow");
                        tncs_done = 1;
                        break;
                case TNCCS_RECOMMENDATION_NONE:
                        wpa_msg(sm->msg_ctx, MSG_INFO,
                                "TNC: Recommendation = none");
                        tncs_done = 1;
                        break;
                case TNCCS_RECOMMENDATION_ISOLATE:
                        wpa_msg(sm->msg_ctx, MSG_INFO,
                                "TNC: Recommendation = isolate");
                        tncs_done = 1;
                        break;
                }
        }

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

        ret->ignore = FALSE;
        ret->methodState = METHOD_MAY_CONT;
        ret->decision = DECISION_UNCOND_SUCC;
        ret->allowNotifications = TRUE;

        if (data->out_buf) {
                data->state = PROC_MSG;
                return eap_tnc_build_msg(data, ret, id);
        }

        if (tncs_done) {
                resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 1,
                                     EAP_CODE_RESPONSE, eap_get_id(reqData));
                if (resp == NULL)
                        return NULL;

                wpabuf_put_u8(resp, EAP_TNC_VERSION);
                wpa_printf(MSG_DEBUG, "EAP-TNC: TNCS done - reply with an "
                           "empty ACK message");
                return resp;
        }

        imc_len = tncc_total_send_len(data->tncc);

        start_buf = tncc_if_tnccs_start(data->tncc);
        if (start_buf == NULL)
                return NULL;
        start_len = os_strlen(start_buf);
        end_buf = tncc_if_tnccs_end();
        if (end_buf == NULL) {
                os_free(start_buf);
                return NULL;
        }
        end_len = os_strlen(end_buf);

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

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

        rpos1 = wpabuf_put(resp, 0);
        rpos = tncc_copy_send_buf(data->tncc, rpos1);
        wpabuf_put(resp, rpos - rpos1);

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

        wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-TNC: Response",
                          wpabuf_head(resp), wpabuf_len(resp));

        data->out_buf = resp;
        data->state = PROC_MSG;
        return eap_tnc_build_msg(data, ret, id);

fail:
        if (data->in_buf == &tmpbuf)
                data->in_buf = NULL;
        return NULL;
}


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

        eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
                                    EAP_VENDOR_IETF, EAP_TYPE_TNC, "TNC");
        if (eap == NULL)
                return -1;

        eap->init = eap_tnc_init;
        eap->deinit = eap_tnc_deinit;
        eap->process = eap_tnc_process;

        ret = eap_peer_method_register(eap);
        if (ret)
                eap_peer_method_free(eap);
        return ret;
}