pxe_image.c

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/*
 * Copyright (C) 2007 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 );

/**
 * @file
 *
 * PXE image format
 *
 */

#include <pxe.h>
#include <pxe_call.h>
#include <pic8259.h>
#include <ipxe/uaccess.h>
#include <ipxe/image.h>
#include <ipxe/segment.h>
#include <ipxe/netdevice.h>
#include <ipxe/features.h>
#include <ipxe/console.h>
#include <ipxe/efi/efi.h>
#include <ipxe/efi/IndustryStandard/PeImage.h>

FEATURE ( FEATURE_IMAGE, "PXE", DHCP_EB_FEATURE_PXE, 1 );

/** PXE command line */
const char *pxe_cmdline;

/**
 * Execute PXE image
 *
 * @v image             PXE image
 * @ret rc              Return status code
 */
static int pxe_exec ( struct image *image ) {
        userptr_t buffer = real_to_user ( 0, 0x7c00 );
        struct net_device *netdev;
        int rc;

        /* Verify and prepare segment */
        if ( ( rc = prep_segment ( buffer, image->len, image->len ) ) != 0 ) {
                DBGC ( image, "IMAGE %p could not prepare segment: %s\n",
                       image, strerror ( rc ) );
                return rc;
        }

        /* Copy image to segment */
        memcpy_user ( buffer, 0, image->data, 0, image->len );

        /* Arbitrarily pick the most recently opened network device */
        if ( ( netdev = last_opened_netdev() ) == NULL ) {
                DBGC ( image, "IMAGE %p could not locate PXE net device\n",
                       image );
                return -ENODEV;
        }
        netdev_get ( netdev );

        /* Activate PXE */
        pxe_activate ( netdev );

        /* Construct fake DHCP packets */
        pxe_fake_cached_info();

        /* Set PXE command line */
        pxe_cmdline = image->cmdline;

        /* Reset console since PXE NBP will probably use it */
        console_reset();

        /* Disable IRQ, if applicable */
        if ( netdev_irq_supported ( netdev ) && netdev->dev->desc.irq )
                disable_irq ( netdev->dev->desc.irq );

        /* Start PXE NBP */
        rc = pxe_start_nbp();

        /* Clear PXE command line */
        pxe_cmdline = NULL;

        /* Deactivate PXE */
        pxe_deactivate();

        /* Try to reopen network device.  Ignore errors, since the NBP
         * may have called PXENV_STOP_UNDI.
         */
        netdev_open ( netdev );
        netdev_put ( netdev );

        return rc;
}

/**
 * Probe PXE image
 *
 * @v image             PXE file
 * @ret rc              Return status code
 */
int pxe_probe ( struct image *image ) {

        /* Images too large to fit in base memory cannot be PXE
         * images.  We include this check to help prevent unrecognised
         * images from being marked as PXE images, since PXE images
         * have no signature we can check against.
         */
        if ( image->len > ( 0xa0000 - 0x7c00 ) )
                return -ENOEXEC;

        /* Rejecting zero-length images is also useful, since these
         * end up looking to the user like bugs in iPXE.
         */
        if ( ! image->len )
                return -ENOEXEC;

        return 0;
}

/**
 * Probe PXE image (with rejection of potential EFI images)
 *
 * @v image             PXE file
 * @ret rc              Return status code
 */
int pxe_probe_no_mz ( struct image *image ) {
        uint16_t magic;
        int rc;

        /* Probe PXE image */
        if ( ( rc = pxe_probe ( image ) ) != 0 )
                return rc;

        /* Reject image with an "MZ" signature which may indicate an
         * EFI image incorrectly handed out to a BIOS system.
         */
        if ( image->len >= sizeof ( magic ) ) {
                copy_from_user ( &magic, image->data, 0, sizeof ( magic ) );
                if ( magic == cpu_to_le16 ( EFI_IMAGE_DOS_SIGNATURE ) ) {
                        DBGC ( image, "IMAGE %p may be an EFI image\n",
                               image );
                        return -ENOTTY;
                }
        }

        return 0;
}

/** PXE image type */
struct image_type pxe_image_type[] __image_type ( PROBE_PXE ) = {
        {
                .name = "PXE-NBP",
                .probe = pxe_probe_no_mz,
                .exec = pxe_exec,
        },
        {
                .name = "PXE-NBP (may be EFI?)",
                .probe = pxe_probe,
                .exec = pxe_exec,
        },
};