1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (c) 2013, Google Inc.
11 #include <openssl/bn.h>
12 #include <openssl/rsa.h>
13 #include <openssl/pem.h>
14 #include <openssl/err.h>
15 #include <openssl/ssl.h>
16 #include <openssl/evp.h>
17 #include <openssl/engine.h>
19 #if OPENSSL_VERSION_NUMBER >= 0x10000000L
20 #define HAVE_ERR_REMOVE_THREAD_STATE
23 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
24 (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
25 static void RSA_get0_key(const RSA *r,
26 const BIGNUM **n, const BIGNUM **e, const BIGNUM **d)
37 static int rsa_err(const char *msg)
39 unsigned long sslErr = ERR_get_error();
41 fprintf(stderr, "%s", msg);
42 fprintf(stderr, ": %s\n",
43 ERR_error_string(sslErr, 0));
49 * rsa_pem_get_pub_key() - read a public key from a .crt file
51 * @keydir: Directory containins the key
52 * @name Name of key file (will have a .crt extension)
53 * @rsap Returns RSA object, or NULL on failure
54 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
56 static int rsa_pem_get_pub_key(const char *keydir, const char *name, RSA **rsap)
66 snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
69 fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
70 path, strerror(errno));
74 /* Read the certificate */
76 if (!PEM_read_X509(f, &cert, NULL, NULL)) {
77 rsa_err("Couldn't read certificate");
82 /* Get the public key from the certificate. */
83 key = X509_get_pubkey(cert);
85 rsa_err("Couldn't read public key\n");
90 /* Convert to a RSA_style key. */
91 rsa = EVP_PKEY_get1_RSA(key);
93 rsa_err("Couldn't convert to a RSA style key");
114 * rsa_engine_get_pub_key() - read a public key from given engine
116 * @keydir: Key prefix
118 * @engine Engine to use
119 * @rsap Returns RSA object, or NULL on failure
120 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
122 static int rsa_engine_get_pub_key(const char *keydir, const char *name,
123 ENGINE *engine, RSA **rsap)
125 const char *engine_id;
133 engine_id = ENGINE_get_id(engine);
135 if (engine_id && !strcmp(engine_id, "pkcs11")) {
137 snprintf(key_id, sizeof(key_id),
138 "pkcs11:%s;object=%s;type=public",
141 snprintf(key_id, sizeof(key_id),
142 "pkcs11:object=%s;type=public",
145 fprintf(stderr, "Engine not supported\n");
149 key = ENGINE_load_public_key(engine, key_id, NULL, NULL);
151 return rsa_err("Failure loading public key from engine");
153 /* Convert to a RSA_style key. */
154 rsa = EVP_PKEY_get1_RSA(key);
156 rsa_err("Couldn't convert to a RSA style key");
172 * rsa_get_pub_key() - read a public key
174 * @keydir: Directory containing the key (PEM file) or key prefix (engine)
175 * @name Name of key file (will have a .crt extension)
176 * @engine Engine to use
177 * @rsap Returns RSA object, or NULL on failure
178 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
180 static int rsa_get_pub_key(const char *keydir, const char *name,
181 ENGINE *engine, RSA **rsap)
184 return rsa_engine_get_pub_key(keydir, name, engine, rsap);
185 return rsa_pem_get_pub_key(keydir, name, rsap);
189 * rsa_pem_get_priv_key() - read a private key from a .key file
191 * @keydir: Directory containing the key
192 * @name Name of key file (will have a .key extension)
193 * @rsap Returns RSA object, or NULL on failure
194 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
196 static int rsa_pem_get_priv_key(const char *keydir, const char *name,
204 snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
205 f = fopen(path, "r");
207 fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
208 path, strerror(errno));
212 rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
214 rsa_err("Failure reading private key");
225 * rsa_engine_get_priv_key() - read a private key from given engine
227 * @keydir: Key prefix
229 * @engine Engine to use
230 * @rsap Returns RSA object, or NULL on failure
231 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
233 static int rsa_engine_get_priv_key(const char *keydir, const char *name,
234 ENGINE *engine, RSA **rsap)
236 const char *engine_id;
244 engine_id = ENGINE_get_id(engine);
246 if (engine_id && !strcmp(engine_id, "pkcs11")) {
248 snprintf(key_id, sizeof(key_id),
249 "pkcs11:%s;object=%s;type=private",
252 snprintf(key_id, sizeof(key_id),
253 "pkcs11:object=%s;type=private",
256 fprintf(stderr, "Engine not supported\n");
260 key = ENGINE_load_private_key(engine, key_id, NULL, NULL);
262 return rsa_err("Failure loading private key from engine");
264 /* Convert to a RSA_style key. */
265 rsa = EVP_PKEY_get1_RSA(key);
267 rsa_err("Couldn't convert to a RSA style key");
283 * rsa_get_priv_key() - read a private key
285 * @keydir: Directory containing the key (PEM file) or key prefix (engine)
287 * @engine Engine to use for signing
288 * @rsap Returns RSA object, or NULL on failure
289 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
291 static int rsa_get_priv_key(const char *keydir, const char *name,
292 ENGINE *engine, RSA **rsap)
295 return rsa_engine_get_priv_key(keydir, name, engine, rsap);
296 return rsa_pem_get_priv_key(keydir, name, rsap);
299 static int rsa_init(void)
303 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
304 (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
305 ret = SSL_library_init();
307 ret = OPENSSL_init_ssl(0, NULL);
310 fprintf(stderr, "Failure to init SSL library\n");
313 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
314 (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
315 SSL_load_error_strings();
317 OpenSSL_add_all_algorithms();
318 OpenSSL_add_all_digests();
319 OpenSSL_add_all_ciphers();
325 static int rsa_engine_init(const char *engine_id, ENGINE **pe)
330 ENGINE_load_builtin_engines();
332 e = ENGINE_by_id(engine_id);
334 fprintf(stderr, "Engine isn't available\n");
336 goto err_engine_by_id;
339 if (!ENGINE_init(e)) {
340 fprintf(stderr, "Couldn't initialize engine\n");
342 goto err_engine_init;
345 if (!ENGINE_set_default_RSA(e)) {
346 fprintf(stderr, "Couldn't set engine as default for RSA\n");
360 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
361 (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
367 static void rsa_remove(void)
369 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
370 (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
371 CRYPTO_cleanup_all_ex_data();
373 #ifdef HAVE_ERR_REMOVE_THREAD_STATE
374 ERR_remove_thread_state(NULL);
382 static void rsa_engine_remove(ENGINE *e)
390 static int rsa_sign_with_key(RSA *rsa, struct padding_algo *padding_algo,
391 struct checksum_algo *checksum_algo,
392 const struct image_region region[], int region_count,
393 uint8_t **sigp, uint *sig_size)
403 key = EVP_PKEY_new();
405 return rsa_err("EVP_PKEY object creation failed");
407 if (!EVP_PKEY_set1_RSA(key, rsa)) {
408 ret = rsa_err("EVP key setup failed");
412 size = EVP_PKEY_size(key);
415 fprintf(stderr, "Out of memory for signature (%zu bytes)\n",
421 context = EVP_MD_CTX_create();
423 ret = rsa_err("EVP context creation failed");
426 EVP_MD_CTX_init(context);
428 ckey = EVP_PKEY_CTX_new(key, NULL);
430 ret = rsa_err("EVP key context creation failed");
434 if (EVP_DigestSignInit(context, &ckey,
435 checksum_algo->calculate_sign(),
437 ret = rsa_err("Signer setup failed");
441 #ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
442 if (padding_algo && !strcmp(padding_algo->name, "pss")) {
443 if (EVP_PKEY_CTX_set_rsa_padding(ckey,
444 RSA_PKCS1_PSS_PADDING) <= 0) {
445 ret = rsa_err("Signer padding setup failed");
449 #endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
451 for (i = 0; i < region_count; i++) {
452 if (!EVP_DigestSignUpdate(context, region[i].data,
454 ret = rsa_err("Signing data failed");
459 if (!EVP_DigestSignFinal(context, sig, &size)) {
460 ret = rsa_err("Could not obtain signature");
464 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
465 (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
466 EVP_MD_CTX_cleanup(context);
468 EVP_MD_CTX_reset(context);
470 EVP_MD_CTX_destroy(context);
473 debug("Got signature: %d bytes, expected %zu\n", *sig_size, size);
480 EVP_MD_CTX_destroy(context);
489 int rsa_sign(struct image_sign_info *info,
490 const struct image_region region[], int region_count,
491 uint8_t **sigp, uint *sig_len)
501 if (info->engine_id) {
502 ret = rsa_engine_init(info->engine_id, &e);
507 ret = rsa_get_priv_key(info->keydir, info->keyname, e, &rsa);
510 ret = rsa_sign_with_key(rsa, info->padding, info->checksum, region,
511 region_count, sigp, sig_len);
517 rsa_engine_remove(e);
526 rsa_engine_remove(e);
533 * rsa_get_exponent(): - Get the public exponent from an RSA key
535 static int rsa_get_exponent(RSA *key, uint64_t *e)
548 RSA_get0_key(key, NULL, &key_e, NULL);
549 if (BN_num_bits(key_e) > 64)
552 *e = BN_get_word(key_e);
554 if (BN_num_bits(key_e) < 33) {
559 bn_te = BN_dup(key_e);
563 if (!BN_rshift(bn_te, bn_te, 32))
566 if (!BN_mask_bits(bn_te, 32))
569 te = BN_get_word(bn_te);
582 * rsa_get_params(): - Get the important parameters of an RSA public key
584 int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
585 BIGNUM **modulusp, BIGNUM **r_squaredp)
587 BIGNUM *big1, *big2, *big32, *big2_32;
588 BIGNUM *n, *r, *r_squared, *tmp;
590 BN_CTX *bn_ctx = BN_CTX_new();
593 /* Initialize BIGNUMs */
598 r_squared = BN_new();
602 if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
604 fprintf(stderr, "Out of memory (bignum)\n");
608 if (0 != rsa_get_exponent(key, exponent))
611 RSA_get0_key(key, &key_n, NULL, NULL);
612 if (!BN_copy(n, key_n) || !BN_set_word(big1, 1L) ||
613 !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
617 if (!BN_exp(big2_32, big2, big32, bn_ctx))
620 /* Calculate n0_inv = -1 / n[0] mod 2^32 */
621 if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
622 !BN_sub(tmp, big2_32, tmp))
624 *n0_invp = BN_get_word(tmp);
626 /* Calculate R = 2^(# of key bits) */
627 if (!BN_set_word(tmp, BN_num_bits(n)) ||
628 !BN_exp(r, big2, tmp, bn_ctx))
631 /* Calculate r_squared = R^2 mod n */
632 if (!BN_copy(r_squared, r) ||
633 !BN_mul(tmp, r_squared, r, bn_ctx) ||
634 !BN_mod(r_squared, tmp, n, bn_ctx))
638 *r_squaredp = r_squared;
647 fprintf(stderr, "Bignum operations failed\n");
654 static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
655 BIGNUM *num, int num_bits)
657 int nwords = num_bits / 32;
660 BIGNUM *tmp, *big2, *big32, *big2_32;
670 * Note: This code assumes that all of the above succeed, or all fail.
671 * In practice memory allocations generally do not fail (unless the
672 * process is killed), so it does not seem worth handling each of these
673 * as a separate case. Technicaly this could leak memory on failure,
674 * but a) it won't happen in practice, and b) it doesn't matter as we
675 * will immediately exit with a failure code.
677 if (!tmp || !big2 || !big32 || !big2_32) {
678 fprintf(stderr, "Out of memory (bignum)\n");
683 fprintf(stderr, "Out of memory (bignum context)\n");
686 BN_set_word(big2, 2L);
687 BN_set_word(big32, 32L);
688 BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
690 size = nwords * sizeof(uint32_t);
693 fprintf(stderr, "Out of memory (%d bytes)\n", size);
697 /* Write out modulus as big endian array of integers */
698 for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
699 BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
700 *ptr = cpu_to_fdt32(BN_get_word(tmp));
701 BN_rshift(num, num, 32); /* N = N/B */
705 * We try signing with successively increasing size values, so this
706 * might fail several times
708 ret = fdt_setprop(blob, noffset, prop_name, buf, size);
715 return ret ? -FDT_ERR_NOSPACE : 0;
718 int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
720 BIGNUM *modulus, *r_squared;
730 debug("%s: Getting verification data\n", __func__);
731 if (info->engine_id) {
732 ret = rsa_engine_init(info->engine_id, &e);
736 ret = rsa_get_pub_key(info->keydir, info->keyname, e, &rsa);
738 goto err_get_pub_key;
739 ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
742 bits = BN_num_bits(modulus);
743 parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
744 if (parent == -FDT_ERR_NOTFOUND) {
745 parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
748 if (ret != -FDT_ERR_NOSPACE) {
749 fprintf(stderr, "Couldn't create signature node: %s\n",
750 fdt_strerror(parent));
757 /* Either create or overwrite the named key node */
758 snprintf(name, sizeof(name), "key-%s", info->keyname);
759 node = fdt_subnode_offset(keydest, parent, name);
760 if (node == -FDT_ERR_NOTFOUND) {
761 node = fdt_add_subnode(keydest, parent, name);
764 if (ret != -FDT_ERR_NOSPACE) {
765 fprintf(stderr, "Could not create key subnode: %s\n",
769 } else if (node < 0) {
770 fprintf(stderr, "Cannot select keys parent: %s\n",
776 ret = fdt_setprop_string(keydest, node, "key-name-hint",
780 ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
782 ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
784 ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
787 ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
791 ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
795 ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
798 if (!ret && info->require_keys) {
799 ret = fdt_setprop_string(keydest, node, "required",
806 ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
811 rsa_engine_remove(e);