// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2013, Google Inc.
*/
#include "mkimage.h"
#include <stdio.h>
#include <string.h>
#include <image.h>
#include <time.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/evp.h>
#include <openssl/engine.h>
#if OPENSSL_VERSION_NUMBER >= 0x10000000L
#define HAVE_ERR_REMOVE_THREAD_STATE
#endif
#if OPENSSL_VERSION_NUMBER < 0x10100000L
static void RSA_get0_key(const RSA *r,
const BIGNUM **n, const BIGNUM **e, const BIGNUM **d)
{
if (n != NULL)
*n = r->n;
if (e != NULL)
*e = r->e;
if (d != NULL)
*d = r->d;
}
#endif
static int rsa_err(const char *msg)
{
unsigned long sslErr = ERR_get_error();
fprintf(stderr, "%s", msg);
fprintf(stderr, ": %s\n",
ERR_error_string(sslErr, 0));
return -1;
}
/**
* rsa_pem_get_pub_key() - read a public key from a .crt file
*
* @keydir: Directory containins the key
* @name Name of key file (will have a .crt extension)
* @rsap Returns RSA object, or NULL on failure
* @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
*/
static int rsa_pem_get_pub_key(const char *keydir, const char *name, RSA **rsap)
{
char path[1024];
EVP_PKEY *key;
X509 *cert;
RSA *rsa;
FILE *f;
int ret;
*rsap = NULL;
snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
f = fopen(path, "r");
if (!f) {
fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
path, strerror(errno));
return -EACCES;
}
/* Read the certificate */
cert = NULL;
if (!PEM_read_X509(f, &cert, NULL, NULL)) {
rsa_err("Couldn't read certificate");
ret = -EINVAL;
goto err_cert;
}
/* Get the public key from the certificate. */
key = X509_get_pubkey(cert);
if (!key) {
rsa_err("Couldn't read public key\n");
ret = -EINVAL;
goto err_pubkey;
}
/* Convert to a RSA_style key. */
rsa = EVP_PKEY_get1_RSA(key);
if (!rsa) {
rsa_err("Couldn't convert to a RSA style key");
ret = -EINVAL;
goto err_rsa;
}
fclose(f);
EVP_PKEY_free(key);
X509_free(cert);
*rsap = rsa;
return 0;
err_rsa:
EVP_PKEY_free(key);
err_pubkey:
X509_free(cert);
err_cert:
fclose(f);
return ret;
}
/**
* rsa_engine_get_pub_key() - read a public key from given engine
*
* @keydir: Key prefix
* @name Name of key
* @engine Engine to use
* @rsap Returns RSA object, or NULL on failure
* @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
*/
static int rsa_engine_get_pub_key(const char *keydir, const char *name,
ENGINE *engine, RSA **rsap)
{
const char *engine_id;
char key_id[1024];
EVP_PKEY *key;
RSA *rsa;
int ret;
*rsap = NULL;
engine_id = ENGINE_get_id(engine);
if (engine_id && !strcmp(engine_id, "pkcs11")) {
if (keydir)
snprintf(key_id, sizeof(key_id),
"pkcs11:%s;object=%s;type=public",
keydir, name);
else
snprintf(key_id, sizeof(key_id),
"pkcs11:object=%s;type=public",
name);
} else {
fprintf(stderr, "Engine not supported\n");
return -ENOTSUP;
}
key = ENGINE_load_public_key(engine, key_id, NULL, NULL);
if (!key)
return rsa_err("Failure loading public key from engine");
/* Convert to a RSA_style key. */
rsa = EVP_PKEY_get1_RSA(key);
if (!rsa) {
rsa_err("Couldn't convert to a RSA style key");
ret = -EINVAL;
goto err_rsa;
}
EVP_PKEY_free(key);
*rsap = rsa;
return 0;
err_rsa:
EVP_PKEY_free(key);
return ret;
}
/**
* rsa_get_pub_key() - read a public key
*
* @keydir: Directory containing the key (PEM file) or key prefix (engine)
* @name Name of key file (will have a .crt extension)
* @engine Engine to use
* @rsap Returns RSA object, or NULL on failure
* @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
*/
static int rsa_get_pub_key(const char *keydir, const char *name,
ENGINE *engine, RSA **rsap)
{
if (engine)
return rsa_engine_get_pub_key(keydir, name, engine, rsap);
return rsa_pem_get_pub_key(keydir, name, rsap);
}
/**
* rsa_pem_get_priv_key() - read a private key from a .key file
*
* @keydir: Directory containing the key
* @name Name of key file (will have a .key extension)
* @rsap Returns RSA object, or NULL on failure
* @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
*/
static int rsa_pem_get_priv_key(const char *keydir, const char *name,
RSA **rsap)
{
char path[1024];
RSA *rsa;
FILE *f;
*rsap = NULL;
snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
f = fopen(path, "r");
if (!f) {
fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
path, strerror(errno));
return -ENOENT;
}
rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
if (!rsa) {
rsa_err("Failure reading private key");
fclose(f);
return -EPROTO;
}
fclose(f);
*rsap = rsa;
return 0;
}
/**
* rsa_engine_get_priv_key() - read a private key from given engine
*
* @keydir: Key prefix
* @name Name of key
* @engine Engine to use
* @rsap Returns RSA object, or NULL on failure
* @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
*/
static int rsa_engine_get_priv_key(const char *keydir, const char *name,
ENGINE *engine, RSA **rsap)
{
const char *engine_id;
char key_id[1024];
EVP_PKEY *key;
RSA *rsa;
int ret;
*rsap = NULL;
engine_id = ENGINE_get_id(engine);
if (engine_id && !strcmp(engine_id, "pkcs11")) {
if (keydir)
snprintf(key_id, sizeof(key_id),
"pkcs11:%s;object=%s;type=private",
keydir, name);
else
snprintf(key_id, sizeof(key_id),
"pkcs11:object=%s;type=private",
name);
} else {
fprintf(stderr, "Engine not supported\n");
return -ENOTSUP;
}
key = ENGINE_load_private_key(engine, key_id, NULL, NULL);
if (!key)
return rsa_err("Failure loading private key from engine");
/* Convert to a RSA_style key. */
rsa = EVP_PKEY_get1_RSA(key);
if (!rsa) {
rsa_err("Couldn't convert to a RSA style key");
ret = -EINVAL;
goto err_rsa;
}
EVP_PKEY_free(key);
*rsap = rsa;
return 0;
err_rsa:
EVP_PKEY_free(key);
return ret;
}
/**
* rsa_get_priv_key() - read a private key
*
* @keydir: Directory containing the key (PEM file) or key prefix (engine)
* @name Name of key
* @engine Engine to use for signing
* @rsap Returns RSA object, or NULL on failure
* @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
*/
static int rsa_get_priv_key(const char *keydir, const char *name,
ENGINE *engine, RSA **rsap)
{
if (engine)
return rsa_engine_get_priv_key(keydir, name, engine, rsap);
return rsa_pem_get_priv_key(keydir, name, rsap);
}
static int rsa_init(void)
{
int ret;
#if OPENSSL_VERSION_NUMBER < 0x10100000L
ret = SSL_library_init();
#else
ret = OPENSSL_init_ssl(0, NULL);
#endif
if (!ret) {
fprintf(stderr, "Failure to init SSL library\n");
return -1;
}
#if OPENSSL_VERSION_NUMBER < 0x10100000L
SSL_load_error_strings();
OpenSSL_add_all_algorithms();
OpenSSL_add_all_digests();
OpenSSL_add_all_ciphers();
#endif
return 0;
}
static int rsa_engine_init(const char *engine_id, ENGINE **pe)
{
ENGINE *e;
int ret;
ENGINE_load_builtin_engines();
e = ENGINE_by_id(engine_id);
if (!e) {
fprintf(stderr, "Engine isn't available\n");
ret = -1;
goto err_engine_by_id;
}
if (!ENGINE_init(e)) {
fprintf(stderr, "Couldn't initialize engine\n");
ret = -1;
goto err_engine_init;
}
if (!ENGINE_set_default_RSA(e)) {
fprintf(stderr, "Couldn't set engine as default for RSA\n");
ret = -1;
goto err_set_rsa;
}
*pe = e;
return 0;
err_set_rsa:
ENGINE_finish(e);
err_engine_init:
ENGINE_free(e);
err_engine_by_id:
#if OPENSSL_VERSION_NUMBER < 0x10100000L
ENGINE_cleanup();
#endif
return ret;
}
static void rsa_remove(void)
{
#if OPENSSL_VERSION_NUMBER < 0x10100000L
CRYPTO_cleanup_all_ex_data();
ERR_free_strings();
#ifdef HAVE_ERR_REMOVE_THREAD_STATE
ERR_remove_thread_state(NULL);
#else
ERR_remove_state(0);
#endif
EVP_cleanup();
#endif
}
static void rsa_engine_remove(ENGINE *e)
{
if (e) {
ENGINE_finish(e);
ENGINE_free(e);
}
}
static int rsa_sign_with_key(RSA *rsa, struct checksum_algo *checksum_algo,
const struct image_region region[], int region_count,
uint8_t **sigp, uint *sig_size)
{
EVP_PKEY *key;
EVP_MD_CTX *context;
int size, ret = 0;
uint8_t *sig;
int i;
key = EVP_PKEY_new();
if (!key)
return rsa_err("EVP_PKEY object creation failed");
if (!EVP_PKEY_set1_RSA(key, rsa)) {
ret = rsa_err("EVP key setup failed");
goto err_set;
}
size = EVP_PKEY_size(key);
sig = malloc(size);
if (!sig) {
fprintf(stderr, "Out of memory for signature (%d bytes)\n",
size);
ret = -ENOMEM;
goto err_alloc;
}
context = EVP_MD_CTX_create();
if (!context) {
ret = rsa_err("EVP context creation failed");
goto err_create;
}
EVP_MD_CTX_init(context);
if (!EVP_SignInit(context, checksum_algo->calculate_sign())) {
ret = rsa_err("Signer setup failed");
goto err_sign;
}
for (i = 0; i < region_count; i++) {
if (!EVP_SignUpdate(context, region[i].data, region[i].size)) {
ret = rsa_err("Signing data failed");
goto err_sign;
}
}
if (!EVP_SignFinal(context, sig, sig_size, key)) {
ret = rsa_err("Could not obtain signature");
goto err_sign;
}
#if OPENSSL_VERSION_NUMBER < 0x10100000L
EVP_MD_CTX_cleanup(context);
#else
EVP_MD_CTX_reset(context);
#endif
EVP_MD_CTX_destroy(context);
EVP_PKEY_free(key);
debug("Got signature: %d bytes, expected %d\n", *sig_size, size);
*sigp = sig;
*sig_size = size;
return 0;
err_sign:
EVP_MD_CTX_destroy(context);
err_create:
free(sig);
err_alloc:
err_set:
EVP_PKEY_free(key);
return ret;
}
int rsa_sign(struct image_sign_info *info,
const struct image_region region[], int region_count,
uint8_t **sigp, uint *sig_len)
{
RSA *rsa;
ENGINE *e = NULL;
int ret;
ret = rsa_init();
if (ret)
return ret;
if (info->engine_id) {
ret = rsa_engine_init(info->engine_id, &e);
if (ret)
goto err_engine;
}
ret = rsa_get_priv_key(info->keydir, info->keyname, e, &rsa);
if (ret)
goto err_priv;
ret = rsa_sign_with_key(rsa, info->checksum, region,
region_count, sigp, sig_len);
if (ret)
goto err_sign;
RSA_free(rsa);
if (info->engine_id)
rsa_engine_remove(e);
rsa_remove();
return ret;
err_sign:
RSA_free(rsa);
err_priv:
if (info->engine_id)
rsa_engine_remove(e);
err_engine:
rsa_remove();
return ret;
}
/*
* rsa_get_exponent(): - Get the public exponent from an RSA key
*/
static int rsa_get_exponent(RSA *key, uint64_t *e)
{
int ret;
BIGNUM *bn_te;
const BIGNUM *key_e;
uint64_t te;
ret = -EINVAL;
bn_te = NULL;
if (!e)
goto cleanup;
RSA_get0_key(key, NULL, &key_e, NULL);
if (BN_num_bits(key_e) > 64)
goto cleanup;
*e = BN_get_word(key_e);
if (BN_num_bits(key_e) < 33) {
ret = 0;
goto cleanup;
}
bn_te = BN_dup(key_e);
if (!bn_te)
goto cleanup;
if (!BN_rshift(bn_te, bn_te, 32))
goto cleanup;
if (!BN_mask_bits(bn_te, 32))
goto cleanup;
te = BN_get_word(bn_te);
te <<= 32;
*e |= te;
ret = 0;
cleanup:
if (bn_te)
BN_free(bn_te);
return ret;
}
/*
* rsa_get_params(): - Get the important parameters of an RSA public key
*/
int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
BIGNUM **modulusp, BIGNUM **r_squaredp)
{
BIGNUM *big1, *big2, *big32, *big2_32;
BIGNUM *n, *r, *r_squared, *tmp;
const BIGNUM *key_n;
BN_CTX *bn_ctx = BN_CTX_new();
int ret = 0;
/* Initialize BIGNUMs */
big1 = BN_new();
big2 = BN_new();
big32 = BN_new();
r = BN_new();
r_squared = BN_new();
tmp = BN_new();
big2_32 = BN_new();
n = BN_new();
if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
!n) {
fprintf(stderr, "Out of memory (bignum)\n");
return -ENOMEM;
}
if (0 != rsa_get_exponent(key, exponent))
ret = -1;
RSA_get0_key(key, &key_n, NULL, NULL);
if (!BN_copy(n, key_n) || !BN_set_word(big1, 1L) ||
!BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
ret = -1;
/* big2_32 = 2^32 */
if (!BN_exp(big2_32, big2, big32, bn_ctx))
ret = -1;
/* Calculate n0_inv = -1 / n[0] mod 2^32 */
if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
!BN_sub(tmp, big2_32, tmp))
ret = -1;
*n0_invp = BN_get_word(tmp);
/* Calculate R = 2^(# of key bits) */
if (!BN_set_word(tmp, BN_num_bits(n)) ||
!BN_exp(r, big2, tmp, bn_ctx))
ret = -1;
/* Calculate r_squared = R^2 mod n */
if (!BN_copy(r_squared, r) ||
!BN_mul(tmp, r_squared, r, bn_ctx) ||
!BN_mod(r_squared, tmp, n, bn_ctx))
ret = -1;
*modulusp = n;
*r_squaredp = r_squared;
BN_free(big1);
BN_free(big2);
BN_free(big32);
BN_free(r);
BN_free(tmp);
BN_free(big2_32);
if (ret) {
fprintf(stderr, "Bignum operations failed\n");
return -ENOMEM;
}
return ret;
}
static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
BIGNUM *num, int num_bits)
{
int nwords = num_bits / 32;
int size;
uint32_t *buf, *ptr;
BIGNUM *tmp, *big2, *big32, *big2_32;
BN_CTX *ctx;
int ret;
tmp = BN_new();
big2 = BN_new();
big32 = BN_new();
big2_32 = BN_new();
/*
* Note: This code assumes that all of the above succeed, or all fail.
* In practice memory allocations generally do not fail (unless the
* process is killed), so it does not seem worth handling each of these
* as a separate case. Technicaly this could leak memory on failure,
* but a) it won't happen in practice, and b) it doesn't matter as we
* will immediately exit with a failure code.
*/
if (!tmp || !big2 || !big32 || !big2_32) {
fprintf(stderr, "Out of memory (bignum)\n");
return -ENOMEM;
}
ctx = BN_CTX_new();
if (!tmp) {
fprintf(stderr, "Out of memory (bignum context)\n");
return -ENOMEM;
}
BN_set_word(big2, 2L);
BN_set_word(big32, 32L);
BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
size = nwords * sizeof(uint32_t);
buf = malloc(size);
if (!buf) {
fprintf(stderr, "Out of memory (%d bytes)\n", size);
return -ENOMEM;
}
/* Write out modulus as big endian array of integers */
for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
*ptr = cpu_to_fdt32(BN_get_word(tmp));
BN_rshift(num, num, 32); /* N = N/B */
}
/*
* We try signing with successively increasing size values, so this
* might fail several times
*/
ret = fdt_setprop(blob, noffset, prop_name, buf, size);
free(buf);
BN_free(tmp);
BN_free(big2);
BN_free(big32);
BN_free(big2_32);
return ret ? -FDT_ERR_NOSPACE : 0;
}
int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
{
BIGNUM *modulus, *r_squared;
uint64_t exponent;
uint32_t n0_inv;
int parent, node;
char name[100];
int ret;
int bits;
RSA *rsa;
ENGINE *e = NULL;
debug("%s: Getting verification data\n", __func__);
if (info->engine_id) {
ret = rsa_engine_init(info->engine_id, &e);
if (ret)
return ret;
}
ret = rsa_get_pub_key(info->keydir, info->keyname, e, &rsa);
if (ret)
goto err_get_pub_key;
ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
if (ret)
goto err_get_params;
bits = BN_num_bits(modulus);
parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
if (parent == -FDT_ERR_NOTFOUND) {
parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
if (parent < 0) {
ret = parent;
if (ret != -FDT_ERR_NOSPACE) {
fprintf(stderr, "Couldn't create signature node: %s\n",
fdt_strerror(parent));
}
}
}
if (ret)
goto done;
/* Either create or overwrite the named key node */
snprintf(name, sizeof(name), "key-%s", info->keyname);
node = fdt_subnode_offset(keydest, parent, name);
if (node == -FDT_ERR_NOTFOUND) {
node = fdt_add_subnode(keydest, parent, name);
if (node < 0) {
ret = node;
if (ret != -FDT_ERR_NOSPACE) {
fprintf(stderr, "Could not create key subnode: %s\n",
fdt_strerror(node));
}
}
} else if (node < 0) {
fprintf(stderr, "Cannot select keys parent: %s\n",
fdt_strerror(node));
ret = node;
}
if (!ret) {
ret = fdt_setprop_string(keydest, node, "key-name-hint",
info->keyname);
}
if (!ret)
ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
if (!ret)
ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
if (!ret) {
ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
}
if (!ret) {
ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
bits);
}
if (!ret) {
ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
bits);
}
if (!ret) {
ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
info->name);
}
if (!ret && info->require_keys) {
ret = fdt_setprop_string(keydest, node, "required",
info->require_keys);
}
done:
BN_free(modulus);
BN_free(r_squared);
if (ret)
ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
err_get_params:
RSA_free(rsa);
err_get_pub_key:
if (info->engine_id)
rsa_engine_remove(e);
return ret;
}