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[efi] Ensure EFI ROM checksum is zero
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The UEFI specification does not mention ROM checksums, and reassigns
the field typically used as a checksum byte.  The UEFI shell
"loadpcirom" utility does not verify ROM checksums, but it seems that
some UEFI BIOSes do.
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Michael Brown committed Jan 9, 2009
1 parent 48b2f70 commit 8fd8134
Showing 1 changed file with 60 additions and 101 deletions.
161 changes: 60 additions & 101 deletions src/util/efirom.c
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Expand Up @@ -21,6 +21,7 @@
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
Expand Down Expand Up @@ -64,91 +65,36 @@ static void * xmalloc ( size_t len ) {
static size_t file_size ( FILE *file ) {
ssize_t len;

if ( fseek ( file, 0, SEEK_END ) != 0 ) {
eprintf ( "Could not seek: %s\n", strerror ( errno ) );
exit ( 1 );
}
len = ftell ( file );
if ( len < 0 ) {
eprintf ( "Could not determine file size: %s\n",
strerror ( errno ) );
exit ( 1 );
}
return len;
}

/**
* Copy file
*
* @v in Input file
* @v out Output file
* @v len Length to copy
*/
static void file_copy ( FILE *in, FILE *out, size_t len ) {
char buf[4096];
size_t frag_len;

while ( len ) {
frag_len = len;
if ( frag_len > sizeof ( buf ) )
frag_len = sizeof ( buf );
if ( fread ( buf, frag_len, 1, in ) != 1 ) {
eprintf ( "Could not read: %s\n",
strerror ( errno ) );
exit ( 1 );
}
if ( fwrite ( buf, frag_len, 1, out ) != 1 ) {
eprintf ( "Could not write: %s\n",
strerror ( errno ) );
exit ( 1 );
}
len -= frag_len;
}
}

/**
* Read information from PE headers
*
* @v pe PE file
* @ret machine Machine type
* @ret subsystem EFI subsystem
*/
static void read_pe_info ( FILE *pe, uint16_t *machine,
static void read_pe_info ( void *pe, uint16_t *machine,
uint16_t *subsystem ) {
EFI_IMAGE_DOS_HEADER dos;
EFI_IMAGE_DOS_HEADER *dos;
union {
EFI_IMAGE_NT_HEADERS32 nt32;
EFI_IMAGE_NT_HEADERS64 nt64;
} nt;

/* Read DOS header */
if ( fseek ( pe, 0, SEEK_SET ) != 0 ) {
eprintf ( "Could not seek: %s\n", strerror ( errno ) );
exit ( 1 );
}
if ( fread ( &dos, sizeof ( dos ), 1, pe ) != 1 ) {
eprintf ( "Could not read: %s\n", strerror ( errno ) );
exit ( 1 );
}

/* Read NT header */
if ( fseek ( pe, dos.e_lfanew, SEEK_SET ) != 0 ) {
eprintf ( "Could not seek: %s\n", strerror ( errno ) );
exit ( 1 );
}
if ( fread ( &nt, sizeof ( nt ), 1, pe ) != 1 ) {
eprintf ( "Could not read: %s\n", strerror ( errno ) );
exit ( 1 );
}
} *nt;

/* Locate NT header */
*machine = nt.nt32.FileHeader.Machine;
dos = pe;
nt = ( pe + dos->e_lfanew );

/* Parse out PE information */
*machine = nt->nt32.FileHeader.Machine;
switch ( *machine ) {
case EFI_IMAGE_MACHINE_IA32:
*subsystem = nt.nt32.OptionalHeader.Subsystem;
*subsystem = nt->nt32.OptionalHeader.Subsystem;
break;
case EFI_IMAGE_MACHINE_X64:
*subsystem = nt.nt64.OptionalHeader.Subsystem;
*subsystem = nt->nt64.OptionalHeader.Subsystem;
break;
default:
eprintf ( "Unrecognised machine type %04x\n", *machine );
Expand All @@ -166,52 +112,65 @@ static void make_efi_rom ( FILE *pe, FILE *rom, struct options *opts ) {
struct {
EFI_PCI_EXPANSION_ROM_HEADER rom;
PCI_DATA_STRUCTURE pci __attribute__ (( aligned ( 4 ) ));
} headers;
uint8_t checksum;
} *headers;
struct stat pe_stat;
size_t pe_size;
size_t rom_size;
unsigned int rom_size_sectors;

/* Determine output file size */
pe_size = file_size ( pe );
rom_size = ( pe_size + sizeof ( headers ) );
rom_size_sectors = ( ( rom_size + 511 ) / 512 );
void *buf;
void *payload;
unsigned int i;
uint8_t checksum;

/* Construct ROM header */
memset ( &headers, 0, sizeof ( headers ) );
headers.rom.Signature = PCI_EXPANSION_ROM_HEADER_SIGNATURE;
headers.rom.InitializationSize = rom_size_sectors;
headers.rom.EfiSignature = EFI_PCI_EXPANSION_ROM_HEADER_EFISIGNATURE;
read_pe_info ( pe, &headers.rom.EfiMachineType,
&headers.rom.EfiSubsystem );
headers.rom.EfiImageHeaderOffset = sizeof ( headers );
headers.rom.PcirOffset =
offsetof ( typeof ( headers ), pci );
headers.pci.Signature = PCI_DATA_STRUCTURE_SIGNATURE;
headers.pci.VendorId = opts->vendor;
headers.pci.DeviceId = opts->device;
headers.pci.Length = sizeof ( headers.pci );
headers.pci.ClassCode[0] = PCI_CLASS_NETWORK;
headers.pci.ImageLength = rom_size_sectors;
headers.pci.CodeType = 0x03; /* No constant in EFI headers? */
headers.pci.Indicator = 0x80; /* No constant in EFI headers? */

/* Write out ROM header */
if ( fwrite ( &headers, sizeof ( headers ), 1, rom ) != 1 ) {
eprintf ( "Could not write headers: %s\n",
/* Determine PE file size */
if ( fstat ( fileno ( pe ), &pe_stat ) != 0 ) {
eprintf ( "Could not stat PE file: %s\n",
strerror ( errno ) );
exit ( 1 );
}
pe_size = pe_stat.st_size;

/* Write out payload */
if ( fseek ( pe, 0, SEEK_SET ) != 0 ) {
eprintf ( "Could not seek: %s\n", strerror ( errno ) );
/* Determine ROM file size */
rom_size = ( ( pe_size + sizeof ( *headers ) + 511 ) & ~511 );

/* Allocate ROM buffer and read in PE file */
buf = xmalloc ( rom_size );
memset ( buf, 0, rom_size );
headers = buf;
payload = ( buf + sizeof ( *headers ) );
if ( fread ( payload, pe_size, 1, pe ) != 1 ) {
eprintf ( "Could not read PE file: %s\n",
strerror ( errno ) );
exit ( 1 );
}
file_copy ( pe, rom, pe_size );

/* Round up to 512-byte boundary */
if ( ftruncate ( fileno ( rom ), ( rom_size_sectors * 512 ) ) != 0 ) {
eprintf ( "Could not set length: %s\n", strerror ( errno ) );
/* Construct ROM header */
headers->rom.Signature = PCI_EXPANSION_ROM_HEADER_SIGNATURE;
headers->rom.InitializationSize = ( rom_size / 512 );
headers->rom.EfiSignature = EFI_PCI_EXPANSION_ROM_HEADER_EFISIGNATURE;
read_pe_info ( payload, &headers->rom.EfiMachineType,
&headers->rom.EfiSubsystem );
headers->rom.EfiImageHeaderOffset = sizeof ( *headers );
headers->rom.PcirOffset =
offsetof ( typeof ( *headers ), pci );
headers->pci.Signature = PCI_DATA_STRUCTURE_SIGNATURE;
headers->pci.VendorId = opts->vendor;
headers->pci.DeviceId = opts->device;
headers->pci.Length = sizeof ( headers->pci );
headers->pci.ClassCode[0] = PCI_CLASS_NETWORK;
headers->pci.ImageLength = ( rom_size / 512 );
headers->pci.CodeType = 0x03; /* No constant in EFI headers? */
headers->pci.Indicator = 0x80; /* No constant in EFI headers? */

/* Fix image checksum */
for ( i = 0, checksum = 0 ; i < rom_size ; i++ )
checksum += *( ( uint8_t * ) buf + i );
headers->checksum -= checksum;

/* Write out ROM */
if ( fwrite ( buf, rom_size, 1, rom ) != 1 ) {
eprintf ( "Could not write ROM file: %s\n",
strerror ( errno ) );
exit ( 1 );
}
}
Expand Down

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