freebsd-dev/usr.sbin/uefisign/pe.c
Marcin Wojtas c97ed06a4b Fix alignment issue in uefisign
The pe_certificate structure has to be aligned to 8 bytes. [1]
Since this is now checked in edk2, any binaries signed with
older version of this tool will fail verification.

References:
[1] https://docs.microsoft.com/en-us/windows/desktop/Debug/pe-format#the-attribute-certificate-table-image-only

Submitted by: Kornel Duleba <mindal@semihalf.com>
Reviewed by: trasz
Obtained from: Semihalf
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D18554
2018-12-19 22:47:37 +00:00

573 lines
16 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2014 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Edward Tomasz Napierala under sponsorship
* from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* PE format reference:
* http://www.microsoft.com/whdc/system/platform/firmware/PECOFF.mspx
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "uefisign.h"
#ifndef CTASSERT
#define CTASSERT(x) _CTASSERT(x, __LINE__)
#define _CTASSERT(x, y) __CTASSERT(x, y)
#define __CTASSERT(x, y) typedef char __assert_ ## y [(x) ? 1 : -1]
#endif
#define PE_ALIGMENT_SIZE 8
struct mz_header {
uint8_t mz_signature[2];
uint8_t mz_dont_care[58];
uint16_t mz_lfanew;
} __attribute__((packed));
struct coff_header {
uint8_t coff_dont_care[2];
uint16_t coff_number_of_sections;
uint8_t coff_dont_care_either[16];
} __attribute__((packed));
#define PE_SIGNATURE 0x00004550
struct pe_header {
uint32_t pe_signature;
struct coff_header pe_coff;
} __attribute__((packed));
#define PE_OPTIONAL_MAGIC_32 0x010B
#define PE_OPTIONAL_MAGIC_32_PLUS 0x020B
#define PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION 10
#define PE_OPTIONAL_SUBSYSTEM_EFI_BOOT 11
#define PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME 12
struct pe_optional_header_32 {
uint16_t po_magic;
uint8_t po_dont_care[58];
uint32_t po_size_of_headers;
uint32_t po_checksum;
uint16_t po_subsystem;
uint8_t po_dont_care_either[22];
uint32_t po_number_of_rva_and_sizes;
} __attribute__((packed));
CTASSERT(offsetof(struct pe_optional_header_32, po_size_of_headers) == 60);
CTASSERT(offsetof(struct pe_optional_header_32, po_checksum) == 64);
CTASSERT(offsetof(struct pe_optional_header_32, po_subsystem) == 68);
CTASSERT(offsetof(struct pe_optional_header_32, po_number_of_rva_and_sizes) == 92);
struct pe_optional_header_32_plus {
uint16_t po_magic;
uint8_t po_dont_care[58];
uint32_t po_size_of_headers;
uint32_t po_checksum;
uint16_t po_subsystem;
uint8_t po_dont_care_either[38];
uint32_t po_number_of_rva_and_sizes;
} __attribute__((packed));
CTASSERT(offsetof(struct pe_optional_header_32_plus, po_size_of_headers) == 60);
CTASSERT(offsetof(struct pe_optional_header_32_plus, po_checksum) == 64);
CTASSERT(offsetof(struct pe_optional_header_32_plus, po_subsystem) == 68);
CTASSERT(offsetof(struct pe_optional_header_32_plus, po_number_of_rva_and_sizes) == 108);
#define PE_DIRECTORY_ENTRY_CERTIFICATE 4
struct pe_directory_entry {
uint32_t pde_rva;
uint32_t pde_size;
} __attribute__((packed));
struct pe_section_header {
uint8_t psh_dont_care[16];
uint32_t psh_size_of_raw_data;
uint32_t psh_pointer_to_raw_data;
uint8_t psh_dont_care_either[16];
} __attribute__((packed));
CTASSERT(offsetof(struct pe_section_header, psh_size_of_raw_data) == 16);
CTASSERT(offsetof(struct pe_section_header, psh_pointer_to_raw_data) == 20);
#define PE_CERTIFICATE_REVISION 0x0200
#define PE_CERTIFICATE_TYPE 0x0002
struct pe_certificate {
uint32_t pc_len;
uint16_t pc_revision;
uint16_t pc_type;
char pc_signature[0];
} __attribute__((packed));
void
range_check(const struct executable *x, off_t off, size_t len,
const char *name)
{
if (off < 0) {
errx(1, "%s starts at negative offset %jd",
name, (intmax_t)off);
}
if (off >= (off_t)x->x_len) {
errx(1, "%s starts at %jd, past the end of executable at %zd",
name, (intmax_t)off, x->x_len);
}
if (len >= x->x_len) {
errx(1, "%s size %zd is larger than the executable size %zd",
name, len, x->x_len);
}
if (off + len > x->x_len) {
errx(1, "%s extends to %jd, past the end of executable at %zd",
name, (intmax_t)(off + len), x->x_len);
}
}
size_t
signature_size(const struct executable *x)
{
const struct pe_directory_entry *pde;
range_check(x, x->x_certificate_entry_off,
x->x_certificate_entry_len, "Certificate Directory");
pde = (struct pe_directory_entry *)
(x->x_buf + x->x_certificate_entry_off);
if (pde->pde_rva != 0 && pde->pde_size == 0)
warnx("signature size is 0, but its RVA is %d", pde->pde_rva);
if (pde->pde_rva == 0 && pde->pde_size != 0)
warnx("signature RVA is 0, but its size is %d", pde->pde_size);
return (pde->pde_size);
}
void
show_certificate(const struct executable *x)
{
struct pe_certificate *pc;
const struct pe_directory_entry *pde;
range_check(x, x->x_certificate_entry_off,
x->x_certificate_entry_len, "Certificate Directory");
pde = (struct pe_directory_entry *)
(x->x_buf + x->x_certificate_entry_off);
if (signature_size(x) == 0) {
printf("file not signed\n");
return;
}
#if 0
printf("certificate chunk at offset %zd, size %zd\n",
pde->pde_rva, pde->pde_size);
#endif
range_check(x, pde->pde_rva, pde->pde_size, "Certificate chunk");
pc = (struct pe_certificate *)(x->x_buf + pde->pde_rva);
if (pc->pc_revision != PE_CERTIFICATE_REVISION) {
errx(1, "wrong certificate chunk revision, is %d, should be %d",
pc->pc_revision, PE_CERTIFICATE_REVISION);
}
if (pc->pc_type != PE_CERTIFICATE_TYPE) {
errx(1, "wrong certificate chunk type, is %d, should be %d",
pc->pc_type, PE_CERTIFICATE_TYPE);
}
printf("to dump PKCS7:\n "
"dd if='%s' bs=1 skip=%zd | openssl pkcs7 -inform DER -print\n",
x->x_path, pde->pde_rva + offsetof(struct pe_certificate, pc_signature));
printf("to dump raw ASN.1:\n "
"openssl asn1parse -i -inform DER -offset %zd -in '%s'\n",
pde->pde_rva + offsetof(struct pe_certificate, pc_signature), x->x_path);
}
static void
parse_section_table(struct executable *x, off_t off, int number_of_sections)
{
const struct pe_section_header *psh;
int i;
range_check(x, off, sizeof(*psh) * number_of_sections,
"section table");
if (x->x_headers_len <= off + sizeof(*psh) * number_of_sections)
errx(1, "section table outside of headers");
psh = (const struct pe_section_header *)(x->x_buf + off);
if (number_of_sections >= MAX_SECTIONS) {
errx(1, "too many sections: got %d, should be %d",
number_of_sections, MAX_SECTIONS);
}
x->x_nsections = number_of_sections;
for (i = 0; i < number_of_sections; i++) {
if (psh->psh_pointer_to_raw_data < x->x_headers_len)
errx(1, "section points inside the headers");
range_check(x, psh->psh_pointer_to_raw_data,
psh->psh_size_of_raw_data, "section");
#if 0
printf("section %d: start %d, size %d\n",
i, psh->psh_pointer_to_raw_data, psh->psh_size_of_raw_data);
#endif
x->x_section_off[i] = psh->psh_pointer_to_raw_data;
x->x_section_len[i] = psh->psh_size_of_raw_data;
psh++;
}
}
static void
parse_directory(struct executable *x, off_t off,
int number_of_rva_and_sizes, int number_of_sections)
{
//int i;
const struct pe_directory_entry *pde;
//printf("Data Directory at offset %zd\n", off);
if (number_of_rva_and_sizes <= PE_DIRECTORY_ENTRY_CERTIFICATE) {
errx(1, "wrong NumberOfRvaAndSizes %d; should be at least %d",
number_of_rva_and_sizes, PE_DIRECTORY_ENTRY_CERTIFICATE);
}
range_check(x, off, sizeof(*pde) * number_of_rva_and_sizes,
"PE Data Directory");
if (x->x_headers_len <= off + sizeof(*pde) * number_of_rva_and_sizes)
errx(1, "PE Data Directory outside of headers");
x->x_certificate_entry_off =
off + sizeof(*pde) * PE_DIRECTORY_ENTRY_CERTIFICATE;
x->x_certificate_entry_len = sizeof(*pde);
#if 0
printf("certificate directory entry at offset %zd, len %zd\n",
x->x_certificate_entry_off, x->x_certificate_entry_len);
pde = (struct pe_directory_entry *)(x->x_buf + off);
for (i = 0; i < number_of_rva_and_sizes; i++) {
printf("rva %zd, size %zd\n", pde->pde_rva, pde->pde_size);
pde++;
}
#endif
return (parse_section_table(x,
off + sizeof(*pde) * number_of_rva_and_sizes, number_of_sections));
}
/*
* The PE checksum algorithm is undocumented; this code is mostly based on
* http://forum.sysinternals.com/optional-header-checksum-calculation_topic24214.html
*
* "Sum the entire image file, excluding the CheckSum field in the optional
* header, as an array of USHORTs, allowing any carry above 16 bits to be added
* back onto the low 16 bits. Then add the file size to get a 32-bit value."
*
* Note that most software does not care about the checksum at all; perhaps
* we could just set it to 0 instead.
*
* XXX: Endianness?
*/
static uint32_t
compute_checksum(const struct executable *x)
{
uint32_t cksum = 0;
uint16_t tmp;
int i;
range_check(x, x->x_checksum_off, x->x_checksum_len, "PE checksum");
assert(x->x_checksum_off % 2 == 0);
for (i = 0; i + sizeof(tmp) < x->x_len; i += 2) {
/*
* Don't checksum the checksum. The +2 is because the checksum
* is 4 bytes, and here we're iterating over 2 byte chunks.
*/
if (i == x->x_checksum_off || i == x->x_checksum_off + 2) {
tmp = 0;
} else {
assert(i + sizeof(tmp) <= x->x_len);
memcpy(&tmp, x->x_buf + i, sizeof(tmp));
}
cksum += tmp;
cksum += cksum >> 16;
cksum &= 0xffff;
}
cksum += cksum >> 16;
cksum &= 0xffff;
cksum += x->x_len;
return (cksum);
}
static void
parse_optional_32_plus(struct executable *x, off_t off,
int number_of_sections)
{
#if 0
uint32_t computed_checksum;
#endif
const struct pe_optional_header_32_plus *po;
range_check(x, off, sizeof(*po), "PE Optional Header");
po = (struct pe_optional_header_32_plus *)(x->x_buf + off);
switch (po->po_subsystem) {
case PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION:
case PE_OPTIONAL_SUBSYSTEM_EFI_BOOT:
case PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME:
break;
default:
errx(1, "wrong PE Optional Header subsystem 0x%x",
po->po_subsystem);
}
#if 0
printf("subsystem %d, checksum 0x%x, %d data directories\n",
po->po_subsystem, po->po_checksum, po->po_number_of_rva_and_sizes);
#endif
x->x_checksum_off = off +
offsetof(struct pe_optional_header_32_plus, po_checksum);
x->x_checksum_len = sizeof(po->po_checksum);
#if 0
printf("checksum 0x%x at offset %zd, len %zd\n",
po->po_checksum, x->x_checksum_off, x->x_checksum_len);
computed_checksum = compute_checksum(x);
if (computed_checksum != po->po_checksum) {
warnx("invalid PE+ checksum; is 0x%x, should be 0x%x",
po->po_checksum, computed_checksum);
}
#endif
if (x->x_len < x->x_headers_len)
errx(1, "invalid SizeOfHeaders %d", po->po_size_of_headers);
x->x_headers_len = po->po_size_of_headers;
//printf("Size of Headers: %d\n", po->po_size_of_headers);
return (parse_directory(x, off + sizeof(*po),
po->po_number_of_rva_and_sizes, number_of_sections));
}
static void
parse_optional_32(struct executable *x, off_t off, int number_of_sections)
{
#if 0
uint32_t computed_checksum;
#endif
const struct pe_optional_header_32 *po;
range_check(x, off, sizeof(*po), "PE Optional Header");
po = (struct pe_optional_header_32 *)(x->x_buf + off);
switch (po->po_subsystem) {
case PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION:
case PE_OPTIONAL_SUBSYSTEM_EFI_BOOT:
case PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME:
break;
default:
errx(1, "wrong PE Optional Header subsystem 0x%x",
po->po_subsystem);
}
#if 0
printf("subsystem %d, checksum 0x%x, %d data directories\n",
po->po_subsystem, po->po_checksum, po->po_number_of_rva_and_sizes);
#endif
x->x_checksum_off = off +
offsetof(struct pe_optional_header_32, po_checksum);
x->x_checksum_len = sizeof(po->po_checksum);
#if 0
printf("checksum at offset %zd, len %zd\n",
x->x_checksum_off, x->x_checksum_len);
computed_checksum = compute_checksum(x);
if (computed_checksum != po->po_checksum) {
warnx("invalid PE checksum; is 0x%x, should be 0x%x",
po->po_checksum, computed_checksum);
}
#endif
if (x->x_len < x->x_headers_len)
errx(1, "invalid SizeOfHeaders %d", po->po_size_of_headers);
x->x_headers_len = po->po_size_of_headers;
//printf("Size of Headers: %d\n", po->po_size_of_headers);
return (parse_directory(x, off + sizeof(*po),
po->po_number_of_rva_and_sizes, number_of_sections));
}
static void
parse_optional(struct executable *x, off_t off, int number_of_sections)
{
const struct pe_optional_header_32 *po;
//printf("Optional header offset %zd\n", off);
range_check(x, off, sizeof(*po), "PE Optional Header");
po = (struct pe_optional_header_32 *)(x->x_buf + off);
switch (po->po_magic) {
case PE_OPTIONAL_MAGIC_32:
return (parse_optional_32(x, off, number_of_sections));
case PE_OPTIONAL_MAGIC_32_PLUS:
return (parse_optional_32_plus(x, off, number_of_sections));
default:
errx(1, "wrong PE Optional Header magic 0x%x", po->po_magic);
}
}
static void
parse_pe(struct executable *x, off_t off)
{
const struct pe_header *pe;
//printf("PE offset %zd, PE size %zd\n", off, sizeof(*pe));
range_check(x, off, sizeof(*pe), "PE header");
pe = (struct pe_header *)(x->x_buf + off);
if (pe->pe_signature != PE_SIGNATURE)
errx(1, "wrong PE signature 0x%x", pe->pe_signature);
//printf("Number of sections: %d\n", pe->pe_coff.coff_number_of_sections);
parse_optional(x, off + sizeof(*pe),
pe->pe_coff.coff_number_of_sections);
}
void
parse(struct executable *x)
{
const struct mz_header *mz;
range_check(x, 0, sizeof(*mz), "MZ header");
mz = (struct mz_header *)x->x_buf;
if (mz->mz_signature[0] != 'M' || mz->mz_signature[1] != 'Z')
errx(1, "MZ header not found");
return (parse_pe(x, mz->mz_lfanew));
}
static off_t
append(struct executable *x, void *ptr, size_t len, size_t aligment)
{
off_t off;
off = x->x_len;
x->x_buf = realloc(x->x_buf, x->x_len + len + aligment);
if (x->x_buf == NULL)
err(1, "realloc");
memcpy(x->x_buf + x->x_len, ptr, len);
memset(x->x_buf + x->x_len + len, 0, aligment);
x->x_len += len + aligment;
return (off);
}
void
update(struct executable *x)
{
uint32_t checksum;
struct pe_certificate *pc;
struct pe_directory_entry pde;
size_t pc_len;
size_t pc_aligment;
off_t pc_off;
pc_len = sizeof(*pc) + x->x_signature_len;
pc = calloc(1, pc_len);
if (pc == NULL)
err(1, "calloc");
if (pc_len % PE_ALIGMENT_SIZE > 0)
pc_aligment = PE_ALIGMENT_SIZE - (pc_len % PE_ALIGMENT_SIZE);
else
pc_aligment = 0;
#if 0
/*
* Note that pc_len is the length of pc_certificate,
* not the whole structure.
*
* XXX: That's what the spec says - but it breaks at least
* sbverify and "pesign -S", so the spec is probably wrong.
*/
pc->pc_len = x->x_signature_len;
#else
pc->pc_len = pc_len;
#endif
pc->pc_revision = PE_CERTIFICATE_REVISION;
pc->pc_type = PE_CERTIFICATE_TYPE;
memcpy(&pc->pc_signature, x->x_signature, x->x_signature_len);
pc_off = append(x, pc, pc_len, pc_aligment);
#if 0
printf("added signature chunk at offset %zd, len %zd\n",
pc_off, pc_len);
#endif
free(pc);
pde.pde_rva = pc_off;
pde.pde_size = pc_len + pc_aligment;
memcpy(x->x_buf + x->x_certificate_entry_off, &pde, sizeof(pde));
checksum = compute_checksum(x);
assert(sizeof(checksum) == x->x_checksum_len);
memcpy(x->x_buf + x->x_checksum_off, &checksum, sizeof(checksum));
#if 0
printf("new checksum 0x%x\n", checksum);
#endif
}