121 lines
3.2 KiB
C
121 lines
3.2 KiB
C
/*
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* Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stdlib.h>
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#include <errno.h>
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#include <assert.h>
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#include <ipxe/asn1.h>
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#include <ipxe/der.h>
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#include <ipxe/uaccess.h>
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#include <ipxe/image.h>
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/** @file
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*
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* DER-encoded ASN.1 data
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*
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*/
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/**
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* Extract ASN.1 object from image
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*
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* @v image DER image
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* @v offset Offset within image
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* @v cursor ASN.1 cursor to fill in
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* @ret next Offset to next image, or negative error
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*
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* The caller is responsible for eventually calling free() on the
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* allocated ASN.1 cursor.
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*/
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static int der_asn1 ( struct image *image, size_t offset __unused,
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struct asn1_cursor **cursor ) {
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void *data;
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/* Allocate cursor and data buffer */
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*cursor = malloc ( sizeof ( **cursor ) + image->len );
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if ( ! *cursor )
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return -ENOMEM;
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data = ( ( ( void * ) *cursor ) + sizeof ( **cursor ) );
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/* Populate cursor and data buffer */
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(*cursor)->data = data;
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(*cursor)->len = image->len;
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copy_from_user ( data, image->data, 0, image->len );
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return image->len;
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}
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/**
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* Probe DER image
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*
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* @v image DER image
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* @ret rc Return status code
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*/
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static int der_probe ( struct image *image ) {
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struct asn1_cursor cursor;
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uint8_t buf[8];
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size_t extra;
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size_t total;
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int len;
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int rc;
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/* Sanity check: no realistic DER image can be smaller than this */
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if ( image->len < sizeof ( buf ) )
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return -ENOEXEC;
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/* Prepare partial cursor */
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cursor.data = buf;
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cursor.len = sizeof ( buf );
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copy_from_user ( buf, image->data, 0, sizeof ( buf ) );
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extra = ( image->len - sizeof ( buf ) );
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/* Get length of ASN.1 sequence */
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len = asn1_start ( &cursor, ASN1_SEQUENCE, extra );
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if ( len < 0 ) {
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rc = len;
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DBGC ( image, "DER %s is not valid ASN.1: %s\n",
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image->name, strerror ( rc ) );
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return rc;
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}
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/* Add length of tag and length bytes consumed by asn1_start() */
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total = ( len + ( cursor.data - ( ( void * ) buf ) ) );
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assert ( total <= image->len );
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/* Check that image comprises a single well-formed ASN.1 object */
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if ( total != image->len ) {
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DBGC ( image, "DER %s is not single ASN.1\n", image->name );
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return -ENOEXEC;
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}
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return 0;
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}
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/** DER image type */
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struct image_type der_image_type __image_type ( PROBE_NORMAL ) = {
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.name = "DER",
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.probe = der_probe,
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.asn1 = der_asn1,
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};
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