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/*
* Copyright (C) 2025 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_SECBOOT ( PERMITTED );
/** @file
*
* EFI signature lists
*
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ipxe/asn1.h>
#include <ipxe/der.h>
#include <ipxe/pem.h>
#include <ipxe/image.h>
#include <ipxe/efi/efi.h>
#include <ipxe/efi/Guid/ImageAuthentication.h>
#include <ipxe/efi/efi_siglist.h>
/**
* Find EFI signature list entry
*
* @v data EFI signature list
* @v len Length of EFI signature list
* @v start Starting offset to update
* @v lhdr Signature list header to fill in
* @v dhdr Signature data header to fill in
* @ret rc Return status code
*/
static int efisig_find ( const void *data, size_t len, size_t *start,
const EFI_SIGNATURE_LIST **lhdr,
const EFI_SIGNATURE_DATA **dhdr ) {
size_t offset;
size_t remaining;
size_t skip;
size_t dlen;
/* Scan through signature list */
offset = 0;
while ( 1 ) {
/* Read list header */
assert ( offset <= len );
remaining = ( len - offset );
if ( remaining < sizeof ( **lhdr ) ) {
DBGC ( data, "EFISIG [%#zx,%#zx) truncated header "
"at +%#zx\n", *start, len, offset );
return -EINVAL;
}
*lhdr = ( data + offset );
/* Get length of this signature list */
if ( remaining < (*lhdr)->SignatureListSize ) {
DBGC ( data, "EFISIG [%#zx,%#zx) truncated list at "
"+%#zx\n", *start, len, offset );
return -EINVAL;
}
remaining = (*lhdr)->SignatureListSize;
/* Get length of each signature in list */
dlen = (*lhdr)->SignatureSize;
if ( dlen < sizeof ( **dhdr ) ) {
DBGC ( data, "EFISIG [%#zx,%#zx) underlength "
"signatures at +%#zx\n", *start, len, offset );
return -EINVAL;
}
/* Strip list header (including variable portion) */
if ( ( remaining < sizeof ( **lhdr ) ) ||
( ( remaining - sizeof ( **lhdr ) ) <
(*lhdr)->SignatureHeaderSize ) ) {
DBGC ( data, "EFISIG [%#zx,%#zx) malformed header at "
"+%#zx\n", *start, len, offset );
return -EINVAL;
}
skip = ( sizeof ( **lhdr ) + (*lhdr)->SignatureHeaderSize );
offset += skip;
remaining -= skip;
/* Read signatures */
for ( ; remaining ; offset += dlen, remaining -= dlen ) {
/* Check length */
if ( remaining < dlen ) {
DBGC ( data, "EFISIG [%#zx,%#zx) truncated "
"at +%#zx\n", *start, len, offset );
return -EINVAL;
}
/* Continue until we find the requested signature */
if ( offset < *start )
continue;
/* Read data header */
*dhdr = ( data + offset );
DBGC2 ( data, "EFISIG [%#zx,%#zx) %s ",
offset, ( offset + dlen ),
efi_guid_ntoa ( &(*lhdr)->SignatureType ) );
DBGC2 ( data, "owner %s\n",
efi_guid_ntoa ( &(*dhdr)->SignatureOwner ) );
*start = offset;
return 0;
}
}
}
/**
* Extract ASN.1 object from EFI signature list
*
* @v data EFI signature list
* @v len Length of EFI signature list
* @v offset Offset within image
* @v cursor ASN.1 cursor to fill in
* @ret next Offset to next image, or negative error
*
* The caller is responsible for eventually calling free() on the
* allocated ASN.1 cursor.
*/
int efisig_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor ) {
const EFI_SIGNATURE_LIST *lhdr;
const EFI_SIGNATURE_DATA *dhdr;
int ( * asn1 ) ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor );
size_t skip = offsetof ( typeof ( *dhdr ), SignatureData );
int next;
int rc;
/* Locate signature list entry */
if ( ( rc = efisig_find ( data, len, &offset, &lhdr, &dhdr ) ) != 0 )
goto err_entry;
len = ( offset + lhdr->SignatureSize );
/* Parse as PEM or DER based on first character */
asn1 = ( ( dhdr->SignatureData[0] == ASN1_SEQUENCE ) ?
der_asn1 : pem_asn1 );
DBGC2 ( data, "EFISIG [%#zx,%#zx) extracting %s\n", offset, len,
( ( asn1 == der_asn1 ) ? "DER" : "PEM" ) );
next = asn1 ( data, len, ( offset + skip ), cursor );
if ( next < 0 ) {
rc = next;
DBGC ( data, "EFISIG [%#zx,%#zx) could not extract ASN.1: "
"%s\n", offset, len, strerror ( rc ) );
goto err_asn1;
}
/* Check that whole entry was consumed */
if ( ( ( unsigned int ) next ) != len ) {
DBGC ( data, "EFISIG [%#zx,%#zx) malformed data\n",
offset, len );
rc = -EINVAL;
goto err_whole;
}
return len;
err_whole:
free ( *cursor );
err_asn1:
err_entry:
return rc;
}
/**
* Probe EFI signature list image
*
* @v image EFI signature list
* @ret rc Return status code
*/
static int efisig_image_probe ( struct image *image ) {
const EFI_SIGNATURE_LIST *lhdr;
const EFI_SIGNATURE_DATA *dhdr;
size_t offset = 0;
unsigned int count = 0;
int rc;
/* Check file is a well-formed signature list */
while ( 1 ) {
/* Find next signature list entry */
if ( ( rc = efisig_find ( image->data, image->len, &offset,
&lhdr, &dhdr ) ) != 0 ) {
return rc;
}
/* Skip this entry */
offset += lhdr->SignatureSize;
count++;
/* Check if we have reached end of the image */
if ( offset == image->len ) {
DBGC ( image, "EFISIG %s contains %d signatures\n",
image->name, count );
return 0;
}
}
}
/**
* Extract ASN.1 object from EFI signature list image
*
* @v image EFI signature list
* @v offset Offset within image
* @v cursor ASN.1 cursor to fill in
* @ret next Offset to next image, or negative error
*
* The caller is responsible for eventually calling free() on the
* allocated ASN.1 cursor.
*/
static int efisig_image_asn1 ( struct image *image, size_t offset,
struct asn1_cursor **cursor ) {
int next;
int rc;
/* Extract ASN.1 object */
if ( ( next = efisig_asn1 ( image->data, image->len, offset,
cursor ) ) < 0 ) {
rc = next;
DBGC ( image, "EFISIG %s could not extract ASN.1: %s\n",
image->name, strerror ( rc ) );
return rc;
}
return next;
}
/** EFI signature list image type */
struct image_type efisig_image_type __image_type ( PROBE_NORMAL ) = {
.name = "EFISIG",
.probe = efisig_image_probe,
.asn1 = efisig_image_asn1,
};
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