freebsd-dev/usr.sbin/uefisign/child.c
Edward Tomasz Napierala bce7ee9d41 Drop "All rights reserved" from all my stuff. This includes
Foundation copyrights, approved by emaste@.  It does not include
files which carry other people's copyrights; if you're one
of those people, feel free to make similar change.

Reviewed by:	emaste, imp, gbe (manpages)
Differential Revision:	https://reviews.freebsd.org/D26980
2020-10-28 13:46:11 +00:00

274 lines
6.5 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2014 The FreeBSD Foundation
*
* 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.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <assert.h>
#include <capsicum_helpers.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include "uefisign.h"
static void
load(struct executable *x)
{
int error, fd;
struct stat sb;
char *buf;
size_t nread, len;
fd = fileno(x->x_fp);
error = fstat(fd, &sb);
if (error != 0)
err(1, "%s: fstat", x->x_path);
len = sb.st_size;
if (len <= 0)
errx(1, "%s: file is empty", x->x_path);
buf = malloc(len);
if (buf == NULL)
err(1, "%s: cannot malloc %zd bytes", x->x_path, len);
nread = fread(buf, len, 1, x->x_fp);
if (nread != 1)
err(1, "%s: fread", x->x_path);
x->x_buf = buf;
x->x_len = len;
}
static void
digest_range(struct executable *x, EVP_MD_CTX *mdctx, off_t off, size_t len)
{
int ok;
range_check(x, off, len, "chunk");
ok = EVP_DigestUpdate(mdctx, x->x_buf + off, len);
if (ok == 0) {
ERR_print_errors_fp(stderr);
errx(1, "EVP_DigestUpdate(3) failed");
}
}
static void
digest(struct executable *x)
{
EVP_MD_CTX *mdctx;
const EVP_MD *md;
size_t sum_of_bytes_hashed;
int i, ok;
/*
* Windows Authenticode Portable Executable Signature Format
* spec version 1.0 specifies MD5 and SHA1. However, pesign
* and sbsign both use SHA256, so do the same.
*/
md = EVP_get_digestbyname(DIGEST);
if (md == NULL) {
ERR_print_errors_fp(stderr);
errx(1, "EVP_get_digestbyname(\"%s\") failed", DIGEST);
}
mdctx = EVP_MD_CTX_create();
if (mdctx == NULL) {
ERR_print_errors_fp(stderr);
errx(1, "EVP_MD_CTX_create(3) failed");
}
ok = EVP_DigestInit_ex(mdctx, md, NULL);
if (ok == 0) {
ERR_print_errors_fp(stderr);
errx(1, "EVP_DigestInit_ex(3) failed");
}
/*
* According to the Authenticode spec, we need to compute
* the digest in a rather... specific manner; see "Calculating
* the PE Image Hash" part of the spec for details.
*
* First, everything from 0 to before the PE checksum.
*/
digest_range(x, mdctx, 0, x->x_checksum_off);
/*
* Second, from after the PE checksum to before the Certificate
* entry in Data Directory.
*/
digest_range(x, mdctx, x->x_checksum_off + x->x_checksum_len,
x->x_certificate_entry_off -
(x->x_checksum_off + x->x_checksum_len));
/*
* Then, from after the Certificate entry to the end of headers.
*/
digest_range(x, mdctx,
x->x_certificate_entry_off + x->x_certificate_entry_len,
x->x_headers_len -
(x->x_certificate_entry_off + x->x_certificate_entry_len));
/*
* Then, each section in turn, as specified in the PE Section Table.
*
* XXX: Sorting.
*/
sum_of_bytes_hashed = x->x_headers_len;
for (i = 0; i < x->x_nsections; i++) {
digest_range(x, mdctx,
x->x_section_off[i], x->x_section_len[i]);
sum_of_bytes_hashed += x->x_section_len[i];
}
/*
* I believe this can happen with overlapping sections.
*/
if (sum_of_bytes_hashed > x->x_len)
errx(1, "number of bytes hashed is larger than file size");
/*
* I can't really explain this one; just do what the spec says.
*/
if (sum_of_bytes_hashed < x->x_len) {
digest_range(x, mdctx, sum_of_bytes_hashed,
x->x_len - (signature_size(x) + sum_of_bytes_hashed));
}
ok = EVP_DigestFinal_ex(mdctx, x->x_digest, &x->x_digest_len);
if (ok == 0) {
ERR_print_errors_fp(stderr);
errx(1, "EVP_DigestFinal_ex(3) failed");
}
EVP_MD_CTX_destroy(mdctx);
}
static void
show_digest(const struct executable *x)
{
int i;
printf("computed %s digest ", DIGEST);
for (i = 0; i < (int)x->x_digest_len; i++)
printf("%02x", (unsigned char)x->x_digest[i]);
printf("; digest len %u\n", x->x_digest_len);
}
static void
send_digest(const struct executable *x, int pipefd)
{
send_chunk(x->x_digest, x->x_digest_len, pipefd);
}
static void
receive_signature(struct executable *x, int pipefd)
{
receive_chunk(&x->x_signature, &x->x_signature_len, pipefd);
}
static void
save(struct executable *x, FILE *fp, const char *path)
{
size_t nwritten;
assert(fp != NULL);
assert(path != NULL);
nwritten = fwrite(x->x_buf, x->x_len, 1, fp);
if (nwritten != 1)
err(1, "%s: fwrite", path);
}
int
child(const char *inpath, const char *outpath, int pipefd,
bool Vflag, bool vflag)
{
FILE *outfp = NULL, *infp = NULL;
struct executable *x;
infp = checked_fopen(inpath, "r");
if (outpath != NULL)
outfp = checked_fopen(outpath, "w");
if (caph_enter() < 0)
err(1, "cap_enter");
x = calloc(1, sizeof(*x));
if (x == NULL)
err(1, "calloc");
x->x_path = inpath;
x->x_fp = infp;
load(x);
parse(x);
if (Vflag) {
if (signature_size(x) == 0)
errx(1, "file not signed");
printf("file contains signature\n");
if (vflag) {
digest(x);
show_digest(x);
show_certificate(x);
}
} else {
if (signature_size(x) != 0)
errx(1, "file already signed");
digest(x);
if (vflag)
show_digest(x);
send_digest(x, pipefd);
receive_signature(x, pipefd);
update(x);
save(x, outfp, outpath);
}
return (0);
}