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osslsigncode/pe.c

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/*
* PE file support library
*
* Copyright (C) 2021-2023 Michał Trojnara <Michal.Trojnara@stunnel.org>
* Author: Małgorzata Olszówka <Malgorzata.Olszowka@stunnel.org>
*
* MS PE/COFF documentation
* https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
*/
#include "osslsigncode.h"
#include "helpers.h"
const u_char classid_page_hash[] = {
0xa6, 0xb5, 0x86, 0xd5, 0xb4, 0xa1, 0x24, 0x66,
0xae, 0x05, 0xa2, 0x17, 0xda, 0x8e, 0x60, 0xd6
};
typedef struct {
ASN1_BIT_STRING *flags;
SpcLink *file;
} SpcPeImageData;
DECLARE_ASN1_FUNCTIONS(SpcPeImageData)
ASN1_SEQUENCE(SpcPeImageData) = {
ASN1_SIMPLE(SpcPeImageData, flags, ASN1_BIT_STRING),
ASN1_EXP_OPT(SpcPeImageData, file, SpcLink, 0)
} ASN1_SEQUENCE_END(SpcPeImageData)
IMPLEMENT_ASN1_FUNCTIONS(SpcPeImageData)
struct pe_ctx_st {
uint32_t header_size;
uint32_t pe32plus;
uint16_t magic;
uint32_t pe_checksum;
uint32_t nrvas;
uint32_t sigpos;
uint32_t siglen;
uint32_t fileend;
};
/* FILE_FORMAT method prototypes */
static FILE_FORMAT_CTX *pe_ctx_new(GLOBAL_OPTIONS *options, BIO *hash, BIO *outdata);
static ASN1_OBJECT *pe_spc_image_data_get(u_char **p, int *plen, FILE_FORMAT_CTX *ctx);
static PKCS7 *pe_pkcs7_contents_get(FILE_FORMAT_CTX *ctx, BIO *hash, const EVP_MD *md);
static int pe_hash_length_get(FILE_FORMAT_CTX *ctx);
static u_char *pe_digest_calc(FILE_FORMAT_CTX *ctx, const EVP_MD *md);
static int pe_verify_digests(FILE_FORMAT_CTX *ctx, PKCS7 *p7);
static int pe_verify_indirect_data(FILE_FORMAT_CTX *ctx, SpcAttributeTypeAndOptionalValue *obj);
static PKCS7 *pe_pkcs7_extract(FILE_FORMAT_CTX *ctx);
static PKCS7 *pe_pkcs7_extract_to_nest(FILE_FORMAT_CTX *ctx);
static int pe_remove_pkcs7(FILE_FORMAT_CTX *ctx, BIO *hash, BIO *outdata);
static int pe_process_data(FILE_FORMAT_CTX *ctx, BIO *hash, BIO *outdata);
static PKCS7 *pe_pkcs7_signature_new(FILE_FORMAT_CTX *ctx, BIO *hash);
static int pe_append_pkcs7(FILE_FORMAT_CTX *ctx, BIO *outdata, PKCS7 *p7);
static void pe_update_data_size(FILE_FORMAT_CTX *ctx, BIO *outdata, PKCS7 *p7);
static void pe_bio_free(BIO *hash, BIO *outdata);
static void pe_ctx_cleanup(FILE_FORMAT_CTX *ctx);
static int pe_is_detaching_supported(void);
FILE_FORMAT file_format_pe = {
.ctx_new = pe_ctx_new,
.data_blob_get = pe_spc_image_data_get,
.pkcs7_contents_get = pe_pkcs7_contents_get,
.hash_length_get = pe_hash_length_get,
.digest_calc = pe_digest_calc,
.verify_digests = pe_verify_digests,
.verify_indirect_data = pe_verify_indirect_data,
.pkcs7_extract = pe_pkcs7_extract,
.pkcs7_extract_to_nest = pe_pkcs7_extract_to_nest,
.remove_pkcs7 = pe_remove_pkcs7,
.process_data = pe_process_data,
.pkcs7_signature_new = pe_pkcs7_signature_new,
.append_pkcs7 = pe_append_pkcs7,
.update_data_size = pe_update_data_size,
.bio_free = pe_bio_free,
.ctx_cleanup = pe_ctx_cleanup,
.is_detaching_supported = pe_is_detaching_supported
};
/* Prototypes */
static PE_CTX *pe_ctx_get(char *indata, uint32_t filesize);
static PKCS7 *pe_pkcs7_get_file(char *indata, PE_CTX *pe_ctx);
static uint32_t pe_calc_checksum(BIO *bio, uint32_t header_size);
static uint32_t pe_calc_realchecksum(FILE_FORMAT_CTX *ctx);
static int pe_modify_header(FILE_FORMAT_CTX *ctx, BIO *hash, BIO *outdata);
static BIO *pe_digest_calc_bio(FILE_FORMAT_CTX *ctx, const EVP_MD *md);
static int pe_page_hash_get(u_char **ph, int *phlen, int *phtype, SpcAttributeTypeAndOptionalValue *obj);
static u_char *pe_page_hash_calc(int *rphlen, FILE_FORMAT_CTX *ctx, int phtype);
static int pe_verify_page_hash(FILE_FORMAT_CTX *ctx, u_char *ph, int phlen, int phtype);
static SpcLink *pe_page_hash_link_get(FILE_FORMAT_CTX *ctx, int phtype);
static int pe_check_file(FILE_FORMAT_CTX *ctx);
/*
* FILE_FORMAT method definitions
*/
/*
* Allocate and return a PE file format context.
* [in, out] options: structure holds the input data
* [out] hash: message digest BIO
* [in] outdata: outdata file BIO
* [returns] pointer to PE file format context
*/
static FILE_FORMAT_CTX *pe_ctx_new(GLOBAL_OPTIONS *options, BIO *hash, BIO *outdata)
{
FILE_FORMAT_CTX *ctx;
PE_CTX *pe_ctx;
uint32_t filesize;
filesize = get_file_size(options->infile);
if (filesize == 0)
return NULL; /* FAILED */
options->indata = map_file(options->infile, filesize);
if (!options->indata) {
return NULL; /* FAILED */
}
if (memcmp(options->indata, "MZ", 2)) {
unmap_file(options->indata, filesize);
return NULL; /* FAILED */
}
pe_ctx = pe_ctx_get(options->indata, filesize);
if (!pe_ctx) {
unmap_file(options->indata, filesize);
return NULL; /* FAILED */
}
ctx = OPENSSL_malloc(sizeof(FILE_FORMAT_CTX));
ctx->format = &file_format_pe;
ctx->options = options;
ctx->pe_ctx = pe_ctx;
/* Push hash on outdata, if hash is NULL the function does nothing */
BIO_push(hash, outdata);
if (options->jp >= 0)
printf("Warning: -jp option is only valid for CAB files\n");
if (options->add_msi_dse == 1)
printf("Warning: -add-msi-dse option is only valid for MSI files\n");
return ctx;
}
/*
* Allocate and return SpcPeImageData object.
* [out] p: SpcPeImageData data
* [out] plen: SpcPeImageData data length
* [in] ctx: structure holds input and output data
* [returns] pointer to ASN1_OBJECT structure corresponding to SPC_PE_IMAGE_DATA_OBJID
*/
static ASN1_OBJECT *pe_spc_image_data_get(u_char **p, int *plen, FILE_FORMAT_CTX *ctx)
{
int phtype;
ASN1_OBJECT *dtype;
SpcPeImageData *pid = SpcPeImageData_new();
ASN1_BIT_STRING_set_bit(pid->flags, 0, 1);
if (ctx->options->pagehash) {
SpcLink *link;
phtype = NID_sha1;
if (EVP_MD_size(ctx->options->md) > EVP_MD_size(EVP_sha1()))
phtype = NID_sha256;
link = pe_page_hash_link_get(ctx, phtype);
if (!link)
return NULL; /* FAILED */
pid->file = link;
} else {
pid->file = spc_link_obsolete_get();
}
*plen = i2d_SpcPeImageData(pid, NULL);
*p = OPENSSL_malloc((size_t)*plen);
i2d_SpcPeImageData(pid, p);
*p -= *plen;
dtype = OBJ_txt2obj(SPC_PE_IMAGE_DATA_OBJID, 1);
SpcPeImageData_free(pid);
return dtype; /* OK */
}
/*
* Allocate and return a data content to be signed.
* [in] ctx: structure holds input and output data
* [in] hash: message digest BIO
* [in] md: message digest algorithm
* [returns] data content
*/
static PKCS7 *pe_pkcs7_contents_get(FILE_FORMAT_CTX *ctx, BIO *hash, const EVP_MD *md)
{
ASN1_OCTET_STRING *content;
BIO *bhash;
/* squash the unused parameter warning */
(void)hash;
bhash = pe_digest_calc_bio(ctx, md);
if (!bhash) {
return NULL; /* FAILED */
}
content = spc_indirect_data_content_get(bhash, ctx);
BIO_free_all(bhash);
return pkcs7_set_content(content);
}
/*
* [in] ctx: structure holds input and output data
* [returns] the size of the message digest when passed an EVP_MD structure (the size of the hash)
*/
static int pe_hash_length_get(FILE_FORMAT_CTX *ctx)
{
return EVP_MD_size(ctx->options->md);
}
/*
* Returns a message digest value of a signed or unsigned PE file.
* [in] ctx: structure holds input and output data
* [in] md: message digest algorithm
* [returns] pointer to calculated message digest
*/
static u_char *pe_digest_calc(FILE_FORMAT_CTX *ctx, const EVP_MD *md)
{
u_char *mdbuf;
BIO *bhash = pe_digest_calc_bio(ctx, md);
if (!bhash) {
return 0; /* FAILED */
}
mdbuf = OPENSSL_malloc((size_t)EVP_MD_size(md));
BIO_gets(bhash, (char*)mdbuf, EVP_MD_size(md));
BIO_free_all(bhash);
return mdbuf; /* OK */
}
/*
* Calculate message digest and page_hash and compare to values retrieved
* from PKCS#7 signedData.
* [in] ctx: structure holds input and output data
* [in] p7: PKCS#7 signature
* [returns] 0 on error or 1 on success
*/
static int pe_verify_digests(FILE_FORMAT_CTX *ctx, PKCS7 *p7)
{
int mdtype = -1, phtype = -1, phlen = 0;
const EVP_MD *md;
u_char mdbuf[EVP_MAX_MD_SIZE];
u_char *cmdbuf = NULL;
u_char *ph = NULL;
if (is_content_type(p7, SPC_INDIRECT_DATA_OBJID)) {
ASN1_STRING *content_val = p7->d.sign->contents->d.other->value.sequence;
const u_char *p = content_val->data;
SpcIndirectDataContent *idc = d2i_SpcIndirectDataContent(NULL, &p, content_val->length);
if (idc) {
if (!pe_page_hash_get(&ph, &phlen, &phtype, idc->data)) {
fprintf(stderr, "Failed to extract a page hash\n\n");
SpcIndirectDataContent_free(idc);
return 0; /* FAILED */
}
if (idc->messageDigest && idc->messageDigest->digest && idc->messageDigest->digestAlgorithm) {
mdtype = OBJ_obj2nid(idc->messageDigest->digestAlgorithm->algorithm);
memcpy(mdbuf, idc->messageDigest->digest->data, (size_t)idc->messageDigest->digest->length);
}
SpcIndirectDataContent_free(idc);
}
}
if (mdtype == -1) {
fprintf(stderr, "Failed to extract current message digest\n\n");
OPENSSL_free(ph);
return 0; /* FAILED */
}
md = EVP_get_digestbynid(mdtype);
cmdbuf = pe_digest_calc(ctx, md);
if (!cmdbuf) {
fprintf(stderr, "Failed to calculate message digest\n\n");
OPENSSL_free(ph);
return 0; /* FAILED */
}
if (!compare_digests(mdbuf, cmdbuf, mdtype)) {
fprintf(stderr, "Signature verification: failed\n\n");
OPENSSL_free(ph);
OPENSSL_free(cmdbuf);
return 0; /* FAILED */
}
if (!pe_verify_page_hash(ctx, ph, phlen, phtype)) {
fprintf(stderr, "Signature verification: failed\n\n");
OPENSSL_free(ph);
OPENSSL_free(cmdbuf);
return 0; /* FAILED */
}
OPENSSL_free(ph);
OPENSSL_free(cmdbuf);
return 1; /* OK */
}
/*
* Verify page hash.
* [in] ctx: structure holds input and output data
* [in] obj: SPC_INDIRECT_DATA OID: 1.3.6.1.4.1.311.2.1.4 containing page hash
* [returns] 0 on error or 1 on success
*/
static int pe_verify_indirect_data(FILE_FORMAT_CTX *ctx, SpcAttributeTypeAndOptionalValue *obj)
{
int phtype = -1, phlen = 0;
u_char *ph = NULL;
if (!pe_page_hash_get(&ph, &phlen, &phtype, obj)) {
fprintf(stderr, "Failed to extract a page hash\n\n");
return 0; /* FAILED */
}
if (!pe_verify_page_hash(ctx, ph, phlen, phtype)) {
fprintf(stderr, "Page hash verification: failed\n\n");
OPENSSL_free(ph);
return 0; /* FAILED */
}
OPENSSL_free(ph);
return 1; /* OK */
}
/*
* Extract existing signature in DER format.
* [in] ctx: structure holds input and output data
* [returns] pointer to PKCS#7 structure
*/
static PKCS7 *pe_pkcs7_extract(FILE_FORMAT_CTX *ctx)
{
if (!pe_check_file(ctx)) {
return NULL; /* FAILED */
}
return pe_pkcs7_get_file(ctx->options->indata, ctx->pe_ctx);
}
/*
* Extract existing signature in DER format.
* [in] ctx: structure holds input and output data
* [returns] pointer to PKCS#7 structure
*/
static PKCS7 *pe_pkcs7_extract_to_nest(FILE_FORMAT_CTX *ctx)
{
return pe_pkcs7_extract(ctx);
}
/*
* Remove existing signature.
* [in, out] ctx: structure holds input and output data
* [out] hash: message digest BIO
* [out] outdata: outdata file BIO
* [returns] 1 on error or 0 on success
*/
static int pe_remove_pkcs7(FILE_FORMAT_CTX *ctx, BIO *hash, BIO *outdata)
{
if (!pe_check_file(ctx)) {
return 1; /* FAILED, no signature */
}
/* Strip current signature */
ctx->pe_ctx->fileend = ctx->pe_ctx->sigpos;
if (!pe_modify_header(ctx, hash, outdata)) {
fprintf(stderr, "Unable to modify file header\n");
return 1; /* FAILED */
}
return 0; /* OK */
}
/*
* Modify specific type data and calculate a hash (message digest) of data.
* [in, out] ctx: structure holds input and output data
* [out] hash: message digest BIO
* [out] outdata: outdata file BIO
* [returns] 1 on error or 0 on success
*/
static int pe_process_data(FILE_FORMAT_CTX *ctx, BIO *hash, BIO *outdata)
{
if (ctx->pe_ctx->sigpos > 0) {
/* Strip current signature */
ctx->pe_ctx->fileend = ctx->pe_ctx->sigpos;
}
if (!pe_modify_header(ctx, hash, outdata)) {
fprintf(stderr, "Unable to modify file header\n");
return 0; /* FAILED */
}
return 1; /* OK */
}
/*
* Create a new PKCS#7 signature.
* [in, out] ctx: structure holds input and output data
* [out] hash: message digest BIO
* [returns] pointer to PKCS#7 structure
*/
static PKCS7 *pe_pkcs7_signature_new(FILE_FORMAT_CTX *ctx, BIO *hash)
{
ASN1_OCTET_STRING *content;
PKCS7 *p7 = pkcs7_create(ctx);
if (!p7) {
fprintf(stderr, "Creating a new signature failed\n");
return NULL; /* FAILED */
}
if (!add_indirect_data_object(p7)) {
fprintf(stderr, "Adding SPC_INDIRECT_DATA_OBJID failed\n");
PKCS7_free(p7);
return NULL; /* FAILED */
}
content = spc_indirect_data_content_get(hash, ctx);
if (!content) {
fprintf(stderr, "Failed to get spcIndirectDataContent\n");
return NULL; /* FAILED */
}
if (!sign_spc_indirect_data_content(p7, content)) {
fprintf(stderr, "Failed to set signed content\n");
PKCS7_free(p7);
ASN1_OCTET_STRING_free(content);
return NULL; /* FAILED */
}
ASN1_OCTET_STRING_free(content);
return p7;
}
/*
* Append signature to the outfile.
* [in, out] ctx: structure holds input and output data (unused)
* [out] outdata: outdata file BIO
* [in] p7: PKCS#7 signature
* [returns] 1 on error or 0 on success
*/
static int pe_append_pkcs7(FILE_FORMAT_CTX *ctx, BIO *outdata, PKCS7 *p7)
{
u_char *p = NULL;
int len; /* signature length */
int padlen; /* signature padding length */
u_char buf[] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
/* squash the unused parameter warning */
(void)ctx;
if (((len = i2d_PKCS7(p7, NULL)) <= 0)
|| (p = OPENSSL_malloc((size_t)len)) == NULL) {
fprintf(stderr, "i2d_PKCS memory allocation failed: %d\n", len);
return 1; /* FAILED */
}
i2d_PKCS7(p7, &p);
p -= len;
padlen = len % 8 ? 8 - len % 8 : 0;
PUT_UINT32_LE(len + 8 + padlen, buf);
PUT_UINT16_LE(WIN_CERT_REVISION_2_0, buf + 4);
PUT_UINT16_LE(WIN_CERT_TYPE_PKCS_SIGNED_DATA, buf + 6);
BIO_write(outdata, buf, 8);
BIO_write(outdata, p, len);
/* pad (with 0's) asn1 blob to 8 byte boundary */
if (padlen > 0) {
memset(p, 0, (size_t)padlen);
BIO_write(outdata, p, padlen);
}
OPENSSL_free(p);
return 0; /* OK */
}
/*
* Update signature position and size, write back new checksum.
* [in, out] ctx: structure holds input and output data
* [out] outdata: outdata file BIO
* [in] p7: PKCS#7 signature
* [returns] none
*/
static void pe_update_data_size(FILE_FORMAT_CTX *ctx, BIO *outdata, PKCS7 *p7)
{
uint32_t checksum;
u_char buf[] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
if (p7) {
int len = i2d_PKCS7(p7, NULL);
int padlen = len % 8 ? 8 - len % 8 : 0;
/* Update signature position and size */
(void)BIO_seek(outdata,
ctx->pe_ctx->header_size + 152 + ctx->pe_ctx->pe32plus * 16);
/* Previous file end = signature table start */
PUT_UINT32_LE(ctx->pe_ctx->fileend, buf);
BIO_write(outdata, buf, 4);
PUT_UINT32_LE(len + 8 + padlen, buf);
BIO_write(outdata, buf, 4);
} /* else CMD_REMOVE */
/* write back checksum */
checksum = pe_calc_checksum(outdata, ctx->pe_ctx->header_size);
(void)BIO_seek(outdata, ctx->pe_ctx->header_size + 88);
PUT_UINT32_LE(checksum, buf);
BIO_write(outdata, buf, 4);
}
/*
* Free up an entire message digest BIO chain.
* [out] hash: message digest BIO
* [out] outdata: outdata file BIO (unused)
* [returns] none
*/
static void pe_bio_free(BIO *hash, BIO *outdata)
{
/* squash the unused parameter warning */
(void)outdata;
BIO_free_all(hash);
}
/*
* Deallocate a FILE_FORMAT_CTX structure and PE format specific structure,
* unmap indata file.
* [out] ctx: structure holds input and output data
* [out] hash: message digest BIO
* [in] outdata: outdata file BIO
* [returns] none
*/
static void pe_ctx_cleanup(FILE_FORMAT_CTX *ctx)
{
unmap_file(ctx->options->indata, ctx->pe_ctx->fileend);
OPENSSL_free(ctx->pe_ctx);
OPENSSL_free(ctx);
}
static int pe_is_detaching_supported(void)
{
return 1; /* OK */
}
/*
* PE helper functions
*/
/*
* Verify mapped PE file and create PE format specific structure.
* [in] indata: mapped PE file
* [in] filesize: size of PE file
* [returns] pointer to PE format specific structure
*/
static PE_CTX *pe_ctx_get(char *indata, uint32_t filesize)
{
PE_CTX *pe_ctx;
uint32_t header_size, pe32plus, pe_checksum, nrvas, sigpos, siglen;
uint16_t magic;
if (filesize < 64) {
fprintf(stderr, "Corrupt DOS file - too short\n");
return NULL; /* FAILED */
}
/* SizeOfHeaders field specifies the combined size of an MS-DOS stub, PE header,
* and section headers rounded up to a multiple of FileAlignment.
* SizeOfHeaders must be < filesize and cannot be < 0x0000002C (44) in Windows 7
* because of a bug when checking section names for compatibility purposes */
header_size = GET_UINT32_LE(indata + 60);
if (header_size < 44 || header_size > filesize) {
fprintf(stderr, "Unexpected SizeOfHeaders field: 0x%08X\n", header_size);
return NULL; /* FAILED */
}
if (filesize < header_size + 176) {
fprintf(stderr, "Corrupt PE file - too short\n");
return NULL; /* FAILED */
}
if (memcmp(indata + header_size, "PE\0\0", 4)) {
fprintf(stderr, "Unrecognized DOS file type\n");
return NULL; /* FAILED */
}
/* Magic field identifies the state of the image file. The most common number is
* 0x10B, which identifies it as a normal executable file,
* 0x20B identifies it as a PE32+ executable,
* 0x107 identifies it as a ROM image (not supported) */
magic = GET_UINT16_LE(indata + header_size + 24);
if (magic == 0x20b) {
pe32plus = 1;
} else if (magic == 0x10b) {
pe32plus = 0;
} else {
fprintf(stderr, "Corrupt PE file - found unknown magic %04X\n", magic);
return NULL; /* FAILED */
}
/* The image file checksum */
pe_checksum = GET_UINT32_LE(indata + header_size + 88);
/* NumberOfRvaAndSizes field specifies the number of data-directory entries
* in the remainder of the optional header. Each describes a location and size. */
nrvas = GET_UINT32_LE(indata + header_size + 116 + pe32plus * 16);
if (nrvas < 5) {
fprintf(stderr, "Can not handle PE files without certificate table resource\n");
return NULL; /* FAILED */
}
/* Certificate Table field specifies the attribute certificate table address (4 bytes) and size (4 bytes) */
sigpos = GET_UINT32_LE(indata + header_size + 152 + pe32plus * 16);
siglen = GET_UINT32_LE(indata + header_size + 152 + pe32plus * 16 + 4);
/* Since fix for MS Bulletin MS12-024 we can really assume
that signature should be last part of file */
if ((sigpos != 0 || siglen != 0) &&
(sigpos == 0 || siglen == 0 || sigpos >= filesize || sigpos + siglen != filesize)) {
printf("Warning: Ignoring PE signature not at the end of the file\n");
sigpos = 0;
siglen = 0;
}
pe_ctx = OPENSSL_zalloc(sizeof(PE_CTX));
pe_ctx->header_size = header_size;
pe_ctx->pe32plus = pe32plus;
pe_ctx->magic = magic;
pe_ctx->pe_checksum = pe_checksum;
pe_ctx->nrvas = nrvas;
pe_ctx->sigpos = sigpos;
pe_ctx->siglen = siglen;
pe_ctx->fileend = filesize;
return pe_ctx; /* OK */
}
/*
* Retrieve and verify a decoded PKCS#7 structure corresponding
* to the existing signature of the PE file.
* [in] indata: mapped PE file
* [in] pe_ctx: PE format specific structures
* [returns] pointer to PKCS#7 structure
*/
static PKCS7 *pe_pkcs7_get_file(char *indata, PE_CTX *pe_ctx)
{
uint32_t pos = 0;
if (pe_ctx->siglen == 0 || pe_ctx->siglen > pe_ctx->fileend) {
fprintf(stderr, "Corrupted signature length: 0x%08X\n", pe_ctx->siglen);
return NULL; /* FAILED */
}
while (pos < pe_ctx->siglen) {
uint32_t len = GET_UINT32_LE(indata + pe_ctx->sigpos + pos);
uint16_t certrev = GET_UINT16_LE(indata + pe_ctx->sigpos + pos + 4);
uint16_t certtype = GET_UINT16_LE(indata + pe_ctx->sigpos + pos + 6);
if (certrev == WIN_CERT_REVISION_2_0 && certtype == WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
/* skip 8 bytes from the attribute certificate table */
const u_char *blob = (u_char *)indata + pe_ctx->sigpos + pos + 8;
return d2i_PKCS7(NULL, &blob, len - 8);
}
/* quadword align data */
len += len % 8 ? 8 - len % 8 : 0;
pos += len;
}
return NULL; /* FAILED */
}
/*
* Calculate checksum.
* A signed PE file is padded (with 0's) to 8 byte boundary,
* ignore any last odd byte in an unsigned file.
* [in] outdata: outdata file BIO
* [in] header_size: PE header size
* [returns] checksum
*/
static uint32_t pe_calc_checksum(BIO *outdata, uint32_t header_size)
{
uint32_t checkSum = 0, offset = 0;
int nread;
unsigned short *buf = OPENSSL_malloc(SIZE_64K);
/* recalculate the checksum */
(void)BIO_seek(outdata, 0);
while ((nread = BIO_read(outdata, buf, SIZE_64K)) > 0) {
unsigned short val;
int i;
for (i = 0; i < nread / 2; i++) {
val = LE_UINT16(buf[i]);
if (offset == header_size + 88 || offset == header_size + 90)
val = 0;
checkSum += val;
checkSum = LOWORD(LOWORD(checkSum) + HIWORD(checkSum));
offset += 2;
}
}
OPENSSL_free(buf);
checkSum = LOWORD(LOWORD(checkSum) + HIWORD(checkSum));
checkSum += offset;
return checkSum;
}
/*
* Compute a checkSum value of the signed or unsigned PE file.
* [in] ctx: structure holds input and output data
* [returns] checksum
*/
static uint32_t pe_calc_realchecksum(FILE_FORMAT_CTX *ctx)
{
uint32_t n = 0, checkSum = 0, offset = 0;
BIO *bio = BIO_new(BIO_s_mem());
unsigned short *buf = OPENSSL_malloc(SIZE_64K);
/* calculate the checkSum */
while (n < ctx->pe_ctx->fileend) {
size_t i, written, nread;
size_t left = ctx->pe_ctx->fileend - n;
unsigned short val;
if (left > SIZE_64K)
left = SIZE_64K;
if (!BIO_write_ex(bio, ctx->options->indata + n, left, &written))
goto err; /* FAILED */
(void)BIO_seek(bio, 0);
n += (uint32_t)written;
if (!BIO_read_ex(bio, buf, written, &nread))
goto err; /* FAILED */
for (i = 0; i < nread / 2; i++) {
val = LE_UINT16(buf[i]);
if (offset == ctx->pe_ctx->header_size + 88
|| offset == ctx->pe_ctx->header_size + 90) {
val = 0;
}
checkSum += val;
checkSum = LOWORD(LOWORD(checkSum) + HIWORD(checkSum));
offset += 2;
}
}
checkSum = LOWORD(LOWORD(checkSum) + HIWORD(checkSum));
checkSum += offset;
err:
OPENSSL_free(buf);
BIO_free(bio);
return checkSum;
}
/*
* Modify PE header.
* [in, out] ctx: structure holds input and output data
* [out] hash: message digest BIO
* [out] outdata: outdata file BIO
* [returns] 1 on error or 0 on success
*/
static int pe_modify_header(FILE_FORMAT_CTX *ctx, BIO *hash, BIO *outdata)
{
size_t i, len, written;
char *buf;
i = len = ctx->pe_ctx->header_size + 88;
if (!BIO_write_ex(hash, ctx->options->indata, len, &written)
|| written != len) {
return 0; /* FAILED */
}
buf = OPENSSL_malloc(SIZE_64K);
memset(buf, 0, 4);
BIO_write(outdata, buf, 4); /* zero out checksum */
i += 4;
len = 60 + ctx->pe_ctx->pe32plus * 16;
if (!BIO_write_ex(hash, ctx->options->indata + i, len, &written)
|| written != len) {
OPENSSL_free(buf);
return 0; /* FAILED */
}
i += 60 + ctx->pe_ctx->pe32plus * 16;
memset(buf, 0, 8);
BIO_write(outdata, buf, 8); /* zero out sigtable offset + pos */
i += 8;
len = ctx->pe_ctx->fileend - i;
while (len > 0) {
if (!BIO_write_ex(hash, ctx->options->indata + i, len, &written)) {
OPENSSL_free(buf);
return 0; /* FAILED */
}
len -= written;
i += written;
}
/* pad (with 0's) pe file to 8 byte boundary */
len = 8 - ctx->pe_ctx->fileend % 8;
if (len != 8) {
memset(buf, 0, len);
if (!BIO_write_ex(hash, buf, len, &written) || written != len) {
OPENSSL_free(buf);
return 0; /* FAILED */
}
ctx->pe_ctx->fileend += (uint32_t)len;
}
OPENSSL_free(buf);
return 1; /* OK */
}
/*
* Compute a message digest value of a signed or unsigned PE file.
* [in] ctx: structure holds input and output data
* [in] md: message digest algorithm
* [returns] calculated message digest BIO
*/
static BIO *pe_digest_calc_bio(FILE_FORMAT_CTX *ctx, const EVP_MD *md)
{
size_t written;
uint32_t idx = 0, fileend;
BIO *bhash = BIO_new(BIO_f_md());
if (!BIO_set_md(bhash, md)) {
fprintf(stderr, "Unable to set the message digest of BIO\n");
BIO_free_all(bhash);
return 0; /* FAILED */
}
BIO_push(bhash, BIO_new(BIO_s_null()));
if (ctx->pe_ctx->sigpos)
fileend = ctx->pe_ctx->sigpos;
else
fileend = ctx->pe_ctx->fileend;
/* ctx->pe_ctx->header_size + 88 + 4 + 60 + ctx->pe_ctx->pe32plus * 16 + 8 */
if (!BIO_write_ex(bhash, ctx->options->indata, ctx->pe_ctx->header_size + 88, &written)
|| written != ctx->pe_ctx->header_size + 88) {
BIO_free_all(bhash);
return 0; /* FAILED */
}
idx += (uint32_t)written + 4;
if (!BIO_write_ex(bhash, ctx->options->indata + idx,
60 + ctx->pe_ctx->pe32plus * 16, &written)
|| written != 60 + ctx->pe_ctx->pe32plus * 16) {
BIO_free_all(bhash);
return 0; /* FAILED */
}
idx += (uint32_t)written + 8;
if (!bio_hash_data(bhash, ctx->options->indata, idx, fileend)) {
fprintf(stderr, "Unable to calculate digest\n");
BIO_free_all(bhash);
return 0; /* FAILED */
}
if (!ctx->pe_ctx->sigpos) {
/* pad (with 0's) unsigned PE file to 8 byte boundary */
int len = 8 - ctx->pe_ctx->fileend % 8;
if (len > 0 && len != 8) {
char *buf = OPENSSL_malloc(8);
memset(buf, 0, (size_t)len);
BIO_write(bhash, buf, len);
OPENSSL_free(buf);
}
}
return bhash;
}
/*
* Page hash support
*/
/*
* Retrieve a page hash from SPC_INDIRECT_DATA structure.
* [out] ph: page hash
* [out] phlen: page hash length
* [out] phtype: NID_sha1 or NID_sha256
* [in] obj: SPC_INDIRECT_DATA OID: 1.3.6.1.4.1.311.2.1.4 containing page hash
* [returns] 0 on error or 1 on success
*/
static int pe_page_hash_get(u_char **ph, int *phlen, int *phtype, SpcAttributeTypeAndOptionalValue *obj)
{
const u_char *blob;
SpcPeImageData *id;
SpcSerializedObject *so;
int l, l2;
char buf[128];
if (!obj || !obj->value)
return 0; /* FAILED */
blob = obj->value->value.sequence->data;
id = d2i_SpcPeImageData(NULL, &blob, obj->value->value.sequence->length);
if (!id) {
return 0; /* FAILED */
}
if (!id->file) {
SpcPeImageData_free(id);
return 0; /* FAILED */
}
if (id->file->type != 1) {
SpcPeImageData_free(id);
return 1; /* OK - This is not SpcSerializedObject structure that contains page hashes */
}
so = id->file->value.moniker;
if (so->classId->length != sizeof classid_page_hash ||
memcmp(so->classId->data, classid_page_hash, sizeof classid_page_hash)) {
SpcPeImageData_free(id);
return 0; /* FAILED */
}
/* skip ASN.1 SET hdr */
l = asn1_simple_hdr_len(so->serializedData->data, so->serializedData->length);
blob = so->serializedData->data + l;
obj = d2i_SpcAttributeTypeAndOptionalValue(NULL, &blob, so->serializedData->length - l);
SpcPeImageData_free(id);
if (!obj)
return 0; /* FAILED */
*phtype = 0;
buf[0] = 0x00;
OBJ_obj2txt(buf, sizeof buf, obj->type, 1);
if (!strcmp(buf, SPC_PE_IMAGE_PAGE_HASHES_V1)) {
*phtype = NID_sha1;
} else if (!strcmp(buf, SPC_PE_IMAGE_PAGE_HASHES_V2)) {
*phtype = NID_sha256;
} else {
SpcAttributeTypeAndOptionalValue_free(obj);
return 0; /* FAILED */
}
/* Skip ASN.1 SET hdr */
l2 = asn1_simple_hdr_len(obj->value->value.sequence->data, obj->value->value.sequence->length);
/* Skip ASN.1 OCTET STRING hdr */
l = asn1_simple_hdr_len(obj->value->value.sequence->data + l2, obj->value->value.sequence->length - l2);
l += l2;
*phlen = obj->value->value.sequence->length - l;
*ph = OPENSSL_malloc((size_t)*phlen);
memcpy(*ph, obj->value->value.sequence->data + l, (size_t)*phlen);
SpcAttributeTypeAndOptionalValue_free(obj);
return 1; /* OK */
}
/*
* Calculate page hash for the PE file.
* [out] rphlen: page hash length
* [in] ctx: structure holds input and output data
* [in] phtype: NID_sha1 or NID_sha256
* [returns] pointer to calculated page hash
*/
static u_char *pe_page_hash_calc(int *rphlen, FILE_FORMAT_CTX *ctx, int phtype)
{
uint16_t nsections, opthdr_size;
uint32_t alignment, pagesize, hdrsize;
uint32_t rs, ro, l, lastpos = 0;
int pphlen, phlen, i, pi = 1;
size_t written;
u_char *res, *zeroes;
char *sections;
const EVP_MD *md = EVP_get_digestbynid(phtype);
BIO *bhash;
/* NumberOfSections indicates the size of the section table,
* which immediately follows the headers, can be up to 65535 under Vista and later */
nsections = GET_UINT16_LE(ctx->options->indata + ctx->pe_ctx->header_size + 6);
if (nsections == 0) {
fprintf(stderr, "Corrupted number of sections: 0x%08X\n", nsections);
return NULL; /* FAILED */
}
/* FileAlignment is the alignment factor (in bytes) that is used to align
* the raw data of sections in the image file. The value should be a power
* of 2 between 512 and 64 K, inclusive. The default is 512. */
alignment = GET_UINT32_LE(ctx->options->indata + ctx->pe_ctx->header_size + 60);
if (alignment < 512 || alignment > UINT16_MAX) {
fprintf(stderr, "Corrupted file alignment factor: 0x%08X\n", alignment);
return NULL; /* FAILED */
}
/* SectionAlignment is the alignment (in bytes) of sections when they are
* loaded into memory. It must be greater than or equal to FileAlignment.
* The default is the page size for the architecture.
* The large page size is at most 4 MB.
* https://devblogs.microsoft.com/oldnewthing/20210510-00/?p=105200 */
pagesize = GET_UINT32_LE(ctx->options->indata + ctx->pe_ctx->header_size + 56);
if (pagesize == 0 || pagesize < alignment || pagesize > 4194304) {
fprintf(stderr, "Corrupted page size: 0x%08X\n", pagesize);
return NULL; /* FAILED */
}
/* SizeOfHeaders is the combined size of an MS-DOS stub, PE header,
* and section headers rounded up to a multiple of FileAlignment. */
hdrsize = GET_UINT32_LE(ctx->options->indata + ctx->pe_ctx->header_size + 84);
if (hdrsize < ctx->pe_ctx->header_size || hdrsize > UINT32_MAX) {
fprintf(stderr, "Corrupted headers size: 0x%08X\n", hdrsize);
return NULL; /* FAILED */
}
/* SizeOfOptionalHeader is the size of the optional header, which is
* required for executable files, but for object files should be zero,
* and can't be bigger than the file */
opthdr_size = GET_UINT16_LE(ctx->options->indata + ctx->pe_ctx->header_size + 20);
if (opthdr_size == 0 || opthdr_size > ctx->pe_ctx->fileend) {
fprintf(stderr, "Corrupted optional header size: 0x%08X\n", opthdr_size);
return NULL; /* FAILED */
}
pphlen = 4 + EVP_MD_size(md);
phlen = pphlen * (3 + (int)nsections + (int)(ctx->pe_ctx->fileend / pagesize));
bhash = BIO_new(BIO_f_md());
if (!BIO_set_md(bhash, md)) {
fprintf(stderr, "Unable to set the message digest of BIO\n");
BIO_free_all(bhash);
return NULL; /* FAILED */
}
BIO_push(bhash, BIO_new(BIO_s_null()));
if (!BIO_write_ex(bhash, ctx->options->indata, ctx->pe_ctx->header_size + 88, &written)
|| written != ctx->pe_ctx->header_size + 88) {
BIO_free_all(bhash);
return NULL; /* FAILED */
}
if (!BIO_write_ex(bhash, ctx->options->indata + ctx->pe_ctx->header_size + 92,
60 + ctx->pe_ctx->pe32plus*16, &written)
|| written != 60 + ctx->pe_ctx->pe32plus*16) {
BIO_free_all(bhash);
return NULL; /* FAILED */
}
if (!BIO_write_ex(bhash,
ctx->options->indata + ctx->pe_ctx->header_size + 160 + ctx->pe_ctx->pe32plus*16,
hdrsize - (ctx->pe_ctx->header_size + 160 + ctx->pe_ctx->pe32plus*16), &written)
|| written != hdrsize - (ctx->pe_ctx->header_size + 160 + ctx->pe_ctx->pe32plus*16)) {
BIO_free_all(bhash);
return NULL; /* FAILED */
}
zeroes = OPENSSL_zalloc((size_t)pagesize);
if (!BIO_write_ex(bhash, zeroes, pagesize - hdrsize, &written)
|| written != pagesize - hdrsize) {
BIO_free_all(bhash);
OPENSSL_free(zeroes);
return NULL; /* FAILED */
}
res = OPENSSL_malloc((size_t)phlen);
memset(res, 0, 4);
BIO_gets(bhash, (char*)res + 4, EVP_MD_size(md));
BIO_free_all(bhash);
sections = ctx->options->indata + ctx->pe_ctx->header_size + 24 + opthdr_size;
for (i=0; i<nsections; i++) {
/* Resource Table address and size */
rs = GET_UINT32_LE(sections + 16);
ro = GET_UINT32_LE(sections + 20);
if (rs == 0 || rs >= UINT32_MAX) {
sections += 40;
continue;
}
for (l=0; l<rs; l+=pagesize, pi++) {
PUT_UINT32_LE(ro + l, res + pi*pphlen);
bhash = BIO_new(BIO_f_md());
if (!BIO_set_md(bhash, md)) {
fprintf(stderr, "Unable to set the message digest of BIO\n");
BIO_free_all(bhash);
OPENSSL_free(zeroes);
OPENSSL_free(res);
return NULL; /* FAILED */
}
BIO_push(bhash, BIO_new(BIO_s_null()));
if (rs - l < pagesize) {
if (!BIO_write_ex(bhash, ctx->options->indata + ro + l, rs - l, &written)
|| written != rs - l) {
BIO_free_all(bhash);
OPENSSL_free(zeroes);
OPENSSL_free(res);
return NULL; /* FAILED */
}
if (!BIO_write_ex(bhash, zeroes, pagesize - (rs - l), &written)
|| written != pagesize - (rs - l)) {
BIO_free_all(bhash);
OPENSSL_free(zeroes);
OPENSSL_free(res);
return NULL; /* FAILED */
}
} else {
if (!BIO_write_ex(bhash, ctx->options->indata + ro + l, pagesize, &written)
|| written != pagesize) {
BIO_free_all(bhash);
OPENSSL_free(zeroes);
OPENSSL_free(res);
return NULL; /* FAILED */
}
}
BIO_gets(bhash, (char*)res + pi*pphlen + 4, EVP_MD_size(md));
BIO_free_all(bhash);
}
lastpos = ro + rs;
sections += 40;
}
PUT_UINT32_LE(lastpos, res + pi*pphlen);
memset(res + pi*pphlen + 4, 0, (size_t)EVP_MD_size(md));
pi++;
OPENSSL_free(zeroes);
*rphlen = pi*pphlen;
return res;
}
/*
* Calculate page hash for the PE file, compare with the given value and print values.
* [in] ctx: structure holds input and output data
* [in] ph: page hash
* [in] phlen: page hash length
* [in] phtype: NID_sha1 or NID_sha256
* [returns] 0 on error or 1 on success
*/
static int pe_verify_page_hash(FILE_FORMAT_CTX *ctx, u_char *ph, int phlen, int phtype)
{
int mdok, cphlen = 0;
u_char *cph;
if (!ph)
return 1; /* OK */
cph = pe_page_hash_calc(&cphlen, ctx, phtype);
mdok = (phlen == cphlen) && !memcmp(ph, cph, (size_t)phlen);
printf("Page hash algorithm : %s\n", OBJ_nid2sn(phtype));
if (ctx->options->verbose) {
print_hash("Page hash ", "", ph, phlen);
print_hash("Calculated page hash ", mdok ? "\n" : "... MISMATCH!!!\n", cph, cphlen);
} else {
print_hash("Page hash ", "...", ph, (phlen < 32) ? phlen : 32);
print_hash("Calculated page hash ", mdok ? "...\n" : "... MISMATCH!!!\n", cph, (cphlen < 32) ? cphlen : 32);
}
OPENSSL_free(cph);
return mdok;
}
/*
* Create a new SpcLink structure.
* [in] ctx: structure holds input and output data
* [in] phtype: NID_sha1 or NID_sha256
* [returns] pointer to SpcLink structure
*/
static SpcLink *pe_page_hash_link_get(FILE_FORMAT_CTX *ctx, int phtype)
{
u_char *ph, *p, *tmp;
int l, phlen;
ASN1_TYPE *tostr;
SpcAttributeTypeAndOptionalValue *aval;
ASN1_TYPE *taval;
SpcSerializedObject *so;
SpcLink *link;
STACK_OF(ASN1_TYPE) *oset, *aset;
ph = pe_page_hash_calc(&phlen, ctx, phtype);
if (!ph) {
fprintf(stderr, "Failed to calculate page hash\n");
return NULL; /* FAILED */
}
if (ctx->options->verbose)
print_hash("Calculated page hash ", "", ph, phlen);
else
print_hash("Calculated page hash ", "...", ph, (phlen < 32) ? phlen : 32);
tostr = ASN1_TYPE_new();
tostr->type = V_ASN1_OCTET_STRING;
tostr->value.octet_string = ASN1_OCTET_STRING_new();
ASN1_OCTET_STRING_set(tostr->value.octet_string, ph, phlen);
OPENSSL_free(ph);
oset = sk_ASN1_TYPE_new_null();
sk_ASN1_TYPE_push(oset, tostr);
l = i2d_ASN1_SET_ANY(oset, NULL);
tmp = p = OPENSSL_malloc((size_t)l);
i2d_ASN1_SET_ANY(oset, &tmp);
ASN1_TYPE_free(tostr);
sk_ASN1_TYPE_free(oset);
aval = SpcAttributeTypeAndOptionalValue_new();
aval->type = OBJ_txt2obj((phtype == NID_sha1) ?
SPC_PE_IMAGE_PAGE_HASHES_V1 : SPC_PE_IMAGE_PAGE_HASHES_V2, 1);
aval->value = ASN1_TYPE_new();
aval->value->type = V_ASN1_SET;
aval->value->value.set = ASN1_STRING_new();
ASN1_STRING_set(aval->value->value.set, p, l);
OPENSSL_free(p);
l = i2d_SpcAttributeTypeAndOptionalValue(aval, NULL);
tmp = p = OPENSSL_malloc((size_t)l);
i2d_SpcAttributeTypeAndOptionalValue(aval, &tmp);
SpcAttributeTypeAndOptionalValue_free(aval);
taval = ASN1_TYPE_new();
taval->type = V_ASN1_SEQUENCE;
taval->value.sequence = ASN1_STRING_new();
ASN1_STRING_set(taval->value.sequence, p, l);
OPENSSL_free(p);
aset = sk_ASN1_TYPE_new_null();
sk_ASN1_TYPE_push(aset, taval);
l = i2d_ASN1_SET_ANY(aset, NULL);
tmp = p = OPENSSL_malloc((size_t)l);
l = i2d_ASN1_SET_ANY(aset, &tmp);
ASN1_TYPE_free(taval);
sk_ASN1_TYPE_free(aset);
so = SpcSerializedObject_new();
ASN1_OCTET_STRING_set(so->classId, classid_page_hash, sizeof classid_page_hash);
ASN1_OCTET_STRING_set(so->serializedData, p, l);
OPENSSL_free(p);
link = SpcLink_new();
link->type = 1;
link->value.moniker = so;
return link;
}
/*
* Print current and calculated PE checksum,
* check if the signature exists.
* [in, out] ctx: structure holds input and output data
* [returns] 0 on error or 1 on success
*/
static int pe_check_file(FILE_FORMAT_CTX *ctx)
{
uint32_t real_pe_checksum, sum = 0;
if (!ctx) {
fprintf(stderr, "Init error\n");
return 0; /* FAILED */
}
real_pe_checksum = pe_calc_realchecksum(ctx);
if (ctx->pe_ctx->pe_checksum == real_pe_checksum) {
printf("PE checksum : %08X\n", real_pe_checksum);
} else {
printf("Current PE checksum : %08X\n", ctx->pe_ctx->pe_checksum);
printf("Calculated PE checksum: %08X\n", real_pe_checksum);
printf("Warning: invalid PE checksum\n");
}
if (ctx->pe_ctx->sigpos == 0 || ctx->pe_ctx->siglen == 0
|| ctx->pe_ctx->sigpos > ctx->pe_ctx->fileend) {
fprintf(stderr, "No signature found\n");
return 0; /* FAILED */
}
/*
* If the sum of the rounded dwLength values does not equal the Size value,
* then either the attribute certificate table or the Size field is corrupted.
*/
while (sum < ctx->pe_ctx->siglen) {
uint32_t len = GET_UINT32_LE(ctx->options->indata + ctx->pe_ctx->sigpos + sum);
if (ctx->pe_ctx->siglen - len > 8) {
fprintf(stderr, "Corrupted attribute certificate table\n");
fprintf(stderr, "Attribute certificate table size : %08X\n", ctx->pe_ctx->siglen);
fprintf(stderr, "Attribute certificate entry length: %08X\n\n", len);
return 0; /* FAILED */
}
/* quadword align data */
len += len % 8 ? 8 - len % 8 : 0;
sum += len;
}
if (sum != ctx->pe_ctx->siglen) {
fprintf(stderr, "Corrupted attribute certificate table\n");
fprintf(stderr, "Attribute certificate table size : %08X\n", ctx->pe_ctx->siglen);
fprintf(stderr, "Sum of the rounded dwLength values: %08X\n\n", sum);
return 0; /* FAILED */
}
return 1; /* OK */
}
/*
Local Variables:
c-basic-offset: 4
tab-width: 4
indent-tabs-mode: nil
End:
vim: set ts=4 expandtab:
*/
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