#define _GNU_SOURCE
#include <assert.h>
#include <getopt.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include "defines.h"
#include "main.h"
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
struct q1q2_ctx {
BN_CTX *bn_ctx;
BIGNUM *m;
BIGNUM *s;
BIGNUM *q1;
BIGNUM *qr;
BIGNUM *q2;
};
static void free_q1q2_ctx(struct q1q2_ctx *ctx)
{
BN_CTX_free(ctx->bn_ctx);
BN_free(ctx->m);
BN_free(ctx->s);
BN_free(ctx->q1);
BN_free(ctx->qr);
BN_free(ctx->q2);
}
static bool alloc_q1q2_ctx(const uint8_t *s, const uint8_t *m,
struct q1q2_ctx *ctx)
{
ctx->bn_ctx = BN_CTX_new();
ctx->s = BN_bin2bn(s, SGX_MODULUS_SIZE, NULL);
ctx->m = BN_bin2bn(m, SGX_MODULUS_SIZE, NULL);
ctx->q1 = BN_new();
ctx->qr = BN_new();
ctx->q2 = BN_new();
if (!ctx->bn_ctx || !ctx->s || !ctx->m || !ctx->q1 || !ctx->qr ||
!ctx->q2) {
free_q1q2_ctx(ctx);
return false;
}
return true;
}
static void reverse_bytes(void *data, int length)
{
int i = 0;
int j = length - 1;
uint8_t temp;
uint8_t *ptr = data;
while (i < j) {
temp = ptr[i];
ptr[i] = ptr[j];
ptr[j] = temp;
i++;
j--;
}
}
static bool calc_q1q2(const uint8_t *s, const uint8_t *m, uint8_t *q1,
uint8_t *q2)
{
struct q1q2_ctx ctx;
int len;
if (!alloc_q1q2_ctx(s, m, &ctx)) {
fprintf(stderr, "Not enough memory for Q1Q2 calculation\n");
return false;
}
if (!BN_mul(ctx.q1, ctx.s, ctx.s, ctx.bn_ctx))
goto out;
if (!BN_div(ctx.q1, ctx.qr, ctx.q1, ctx.m, ctx.bn_ctx))
goto out;
if (BN_num_bytes(ctx.q1) > SGX_MODULUS_SIZE) {
fprintf(stderr, "Too large Q1 %d bytes\n",
BN_num_bytes(ctx.q1));
goto out;
}
if (!BN_mul(ctx.q2, ctx.s, ctx.qr, ctx.bn_ctx))
goto out;
if (!BN_div(ctx.q2, NULL, ctx.q2, ctx.m, ctx.bn_ctx))
goto out;
if (BN_num_bytes(ctx.q2) > SGX_MODULUS_SIZE) {
fprintf(stderr, "Too large Q2 %d bytes\n",
BN_num_bytes(ctx.q2));
goto out;
}
len = BN_bn2bin(ctx.q1, q1);
reverse_bytes(q1, len);
len = BN_bn2bin(ctx.q2, q2);
reverse_bytes(q2, len);
free_q1q2_ctx(&ctx);
return true;
out:
free_q1q2_ctx(&ctx);
return false;
}
struct sgx_sigstruct_payload {
struct sgx_sigstruct_header header;
struct sgx_sigstruct_body body;
};
static bool check_crypto_errors(void)
{
int err;
bool had_errors = false;
const char *filename;
int line;
char str[256];
for ( ; ; ) {
if (ERR_peek_error() == 0)
break;
had_errors = true;
err = ERR_get_error_line(&filename, &line);
ERR_error_string_n(err, str, sizeof(str));
fprintf(stderr, "crypto: %s: %s:%d\n", str, filename, line);
}
return had_errors;
}
static inline const BIGNUM *get_modulus(RSA *key)
{
const BIGNUM *n;
RSA_get0_key(key, &n, NULL, NULL);
return n;
}
static RSA *gen_sign_key(void)
{
unsigned long sign_key_length;
BIO *bio;
RSA *key;
sign_key_length = (unsigned long)&sign_key_end -
(unsigned long)&sign_key;
bio = BIO_new_mem_buf(&sign_key, sign_key_length);
if (!bio)
return NULL;
key = PEM_read_bio_RSAPrivateKey(bio, NULL, NULL, NULL);
BIO_free(bio);
return key;
}
enum mrtags {
MRECREATE = 0x0045544145524345,
MREADD = 0x0000000044444145,
MREEXTEND = 0x00444E4554584545,
};
static bool mrenclave_update(EVP_MD_CTX *ctx, const void *data)
{
if (!EVP_DigestUpdate(ctx, data, 64)) {
fprintf(stderr, "digest update failed\n");
return false;
}
return true;
}
static bool mrenclave_commit(EVP_MD_CTX *ctx, uint8_t *mrenclave)
{
unsigned int size;
if (!EVP_DigestFinal_ex(ctx, (unsigned char *)mrenclave, &size)) {
fprintf(stderr, "digest commit failed\n");
return false;
}
if (size != 32) {
fprintf(stderr, "invalid digest size = %u\n", size);
return false;
}
return true;
}
struct mrecreate {
uint64_t tag;
uint32_t ssaframesize;
uint64_t size;
uint8_t reserved[44];
} __attribute__((__packed__));
static bool mrenclave_ecreate(EVP_MD_CTX *ctx, uint64_t blob_size)
{
struct mrecreate mrecreate;
uint64_t encl_size;
for (encl_size = 0x1000; encl_size < blob_size; )
encl_size <<= 1;
memset(&mrecreate, 0, sizeof(mrecreate));
mrecreate.tag = MRECREATE;
mrecreate.ssaframesize = 1;
mrecreate.size = encl_size;
if (!EVP_DigestInit_ex(ctx, EVP_sha256(), NULL))
return false;
return mrenclave_update(ctx, &mrecreate);
}
struct mreadd {
uint64_t tag;
uint64_t offset;
uint64_t flags;
uint8_t reserved[40];
} __attribute__((__packed__));
static bool mrenclave_eadd(EVP_MD_CTX *ctx, uint64_t offset, uint64_t flags)
{
struct mreadd mreadd;
memset(&mreadd, 0, sizeof(mreadd));
mreadd.tag = MREADD;
mreadd.offset = offset;
mreadd.flags = flags;
return mrenclave_update(ctx, &mreadd);
}
struct mreextend {
uint64_t tag;
uint64_t offset;
uint8_t reserved[48];
} __attribute__((__packed__));
static bool mrenclave_eextend(EVP_MD_CTX *ctx, uint64_t offset,
const uint8_t *data)
{
struct mreextend mreextend;
int i;
for (i = 0; i < 0x1000; i += 0x100) {
memset(&mreextend, 0, sizeof(mreextend));
mreextend.tag = MREEXTEND;
mreextend.offset = offset + i;
if (!mrenclave_update(ctx, &mreextend))
return false;
if (!mrenclave_update(ctx, &data[i + 0x00]))
return false;
if (!mrenclave_update(ctx, &data[i + 0x40]))
return false;
if (!mrenclave_update(ctx, &data[i + 0x80]))
return false;
if (!mrenclave_update(ctx, &data[i + 0xC0]))
return false;
}
return true;
}
static bool mrenclave_segment(EVP_MD_CTX *ctx, struct encl *encl,
struct encl_segment *seg)
{
uint64_t end = seg->size;
uint64_t offset;
for (offset = 0; offset < end; offset += PAGE_SIZE) {
if (!mrenclave_eadd(ctx, seg->offset + offset, seg->flags))
return false;
if (seg->measure) {
if (!mrenclave_eextend(ctx, seg->offset + offset, seg->src + offset))
return false;
}
}
return true;
}
bool encl_measure(struct encl *encl)
{
uint64_t header1[2] = {0x000000E100000006, 0x0000000000010000};
uint64_t header2[2] = {0x0000006000000101, 0x0000000100000060};
struct sgx_sigstruct *sigstruct = &encl->sigstruct;
struct sgx_sigstruct_payload payload;
uint8_t digest[SHA256_DIGEST_LENGTH];
EVP_MD_CTX *ctx = NULL;
unsigned int siglen;
RSA *key = NULL;
int i;
memset(sigstruct, 0, sizeof(*sigstruct));
sigstruct->header.header1[0] = header1[0];
sigstruct->header.header1[1] = header1[1];
sigstruct->header.header2[0] = header2[0];
sigstruct->header.header2[1] = header2[1];
sigstruct->exponent = 3;
sigstruct->body.attributes = SGX_ATTR_MODE64BIT;
sigstruct->body.xfrm = 3;
if (check_crypto_errors())
goto err;
key = gen_sign_key();
if (!key) {
ERR_print_errors_fp(stdout);
goto err;
}
BN_bn2bin(get_modulus(key), sigstruct->modulus);
ctx = EVP_MD_CTX_create();
if (!ctx)
goto err;
if (!mrenclave_ecreate(ctx, encl->src_size))
goto err;
for (i = 0; i < encl->nr_segments; i++) {
struct encl_segment *seg = &encl->segment_tbl[i];
if (!mrenclave_segment(ctx, encl, seg))
goto err;
}
if (!mrenclave_commit(ctx, sigstruct->body.mrenclave))
goto err;
memcpy(&payload.header, &sigstruct->header, sizeof(sigstruct->header));
memcpy(&payload.body, &sigstruct->body, sizeof(sigstruct->body));
SHA256((unsigned char *)&payload, sizeof(payload), digest);
if (!RSA_sign(NID_sha256, digest, SHA256_DIGEST_LENGTH,
sigstruct->signature, &siglen, key))
goto err;
if (!calc_q1q2(sigstruct->signature, sigstruct->modulus, sigstruct->q1,
sigstruct->q2))
goto err;
reverse_bytes(sigstruct->signature, SGX_MODULUS_SIZE);
reverse_bytes(sigstruct->modulus, SGX_MODULUS_SIZE);
EVP_MD_CTX_destroy(ctx);
RSA_free(key);
return true;
err:
if (ctx)
EVP_MD_CTX_destroy(ctx);
RSA_free(key);
return false;
}
