eapol.c

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/*
 * Copyright (C) 2021 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * 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 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 Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <assert.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/iobuf.h>
#include <ipxe/if_ether.h>
#include <ipxe/netdevice.h>
#include <ipxe/eap.h>
#include <ipxe/eapol.h>

/** @file
 *
 * Extensible Authentication Protocol over LAN (EAPoL)
 *
 */

/**
 * Process EAPoL packet
 *
 * @v iobuf             I/O buffer
 * @v netdev            Network device
 * @v ll_dest           Link-layer destination address
 * @v ll_source         Link-layer source address
 * @v flags             Packet flags
 * @ret rc              Return status code
 */
static int eapol_rx ( struct io_buffer *iobuf, struct net_device *netdev,
                      const void *ll_dest __unused, const void *ll_source,
                      unsigned int flags __unused ) {
        struct eapol_header *eapol;
        struct eapol_handler *handler;
        size_t remaining;
        size_t len;
        int rc;

        /* Sanity checks */
        if ( iob_len ( iobuf ) < sizeof ( *eapol ) ) {
                DBGC ( netdev, "EAPOL %s underlength header:\n",
                       netdev->name );
                DBGC_HDA ( netdev, 0, iobuf->data, iob_len ( iobuf ) );
                rc = -EINVAL;
                goto drop;
        }
        eapol = iobuf->data;
        remaining = ( iob_len ( iobuf ) - sizeof ( *eapol ) );
        len = ntohs ( eapol->len );
        if ( len > remaining ) {
                DBGC ( netdev, "EAPOL %s v%d type %d len %zd underlength "
                       "payload:\n", netdev->name, eapol->version,
                       eapol->type, len );
                DBGC_HDA ( netdev, 0, iobuf->data, iob_len ( iobuf ) );
                rc = -EINVAL;
                goto drop;
        }

        /* Strip any trailing padding */
        iob_unput ( iobuf, ( len - remaining ) );

        /* Handle according to type */
        for_each_table_entry ( handler, EAPOL_HANDLERS ) {
                if ( handler->type == eapol->type ) {
                        return handler->rx ( iob_disown ( iobuf ) , netdev,
                                             ll_source );
                }
        }
        rc = -ENOTSUP;
        DBGC ( netdev, "EAPOL %s v%d type %d unsupported\n",
               netdev->name, eapol->version, eapol->type );
        DBGC_HDA ( netdev, 0, iobuf->data, iob_len ( iobuf ) );

 drop:
        free_iob ( iobuf );
        return rc;
}

/** EAPoL protocol */
struct net_protocol eapol_protocol __net_protocol = {
        .name = "EAPOL",
        .net_proto = htons ( ETH_P_EAPOL ),
        .rx = eapol_rx,
};

/**
 * Process EAPoL-encapsulated EAP packet
 *
 * @v netdev            Network device
 * @v ll_source         Link-layer source address
 * @ret rc              Return status code
 */
static int eapol_eap_rx ( struct io_buffer *iobuf, struct net_device *netdev,
                          const void *ll_source __unused ) {
        struct eapol_header *eapol;
        int rc;

        /* Sanity check */
        assert ( iob_len ( iobuf ) >= sizeof ( *eapol ) );

        /* Strip EAPoL header */
        eapol = iob_pull ( iobuf, sizeof ( *eapol ) );

        /* Process EAP packet */
        if ( ( rc = eap_rx ( netdev, iobuf->data, iob_len ( iobuf ) ) ) != 0 ) {
                DBGC ( netdev, "EAPOL %s v%d EAP failed: %s\n",
                       netdev->name, eapol->version, strerror ( rc ) );
                goto drop;
        }

 drop:
        free_iob ( iobuf );
        return rc;
}

/** EAPoL handler for EAP packets */
struct eapol_handler eapol_eap __eapol_handler = {
        .type = EAPOL_TYPE_EAP,
        .rx = eapol_eap_rx,
};