xref: /openbmc/u-boot/lib/rsa/rsa-sign.c (revision fb1b7712)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (c) 2013, Google Inc.
4  */
5 
6 #include "mkimage.h"
7 #include <stdio.h>
8 #include <string.h>
9 #include <image.h>
10 #include <time.h>
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>
18 
19 #if OPENSSL_VERSION_NUMBER >= 0x10000000L
20 #define HAVE_ERR_REMOVE_THREAD_STATE
21 #endif
22 
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)
27 {
28    if (n != NULL)
29        *n = r->n;
30    if (e != NULL)
31        *e = r->e;
32    if (d != NULL)
33        *d = r->d;
34 }
35 #endif
36 
37 static int rsa_err(const char *msg)
38 {
39 	unsigned long sslErr = ERR_get_error();
40 
41 	fprintf(stderr, "%s", msg);
42 	fprintf(stderr, ": %s\n",
43 		ERR_error_string(sslErr, 0));
44 
45 	return -1;
46 }
47 
48 /**
49  * rsa_pem_get_pub_key() - read a public key from a .crt file
50  *
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)
55  */
56 static int rsa_pem_get_pub_key(const char *keydir, const char *name, RSA **rsap)
57 {
58 	char path[1024];
59 	EVP_PKEY *key;
60 	X509 *cert;
61 	RSA *rsa;
62 	FILE *f;
63 	int ret;
64 
65 	*rsap = NULL;
66 	snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
67 	f = fopen(path, "r");
68 	if (!f) {
69 		fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
70 			path, strerror(errno));
71 		return -EACCES;
72 	}
73 
74 	/* Read the certificate */
75 	cert = NULL;
76 	if (!PEM_read_X509(f, &cert, NULL, NULL)) {
77 		rsa_err("Couldn't read certificate");
78 		ret = -EINVAL;
79 		goto err_cert;
80 	}
81 
82 	/* Get the public key from the certificate. */
83 	key = X509_get_pubkey(cert);
84 	if (!key) {
85 		rsa_err("Couldn't read public key\n");
86 		ret = -EINVAL;
87 		goto err_pubkey;
88 	}
89 
90 	/* Convert to a RSA_style key. */
91 	rsa = EVP_PKEY_get1_RSA(key);
92 	if (!rsa) {
93 		rsa_err("Couldn't convert to a RSA style key");
94 		ret = -EINVAL;
95 		goto err_rsa;
96 	}
97 	fclose(f);
98 	EVP_PKEY_free(key);
99 	X509_free(cert);
100 	*rsap = rsa;
101 
102 	return 0;
103 
104 err_rsa:
105 	EVP_PKEY_free(key);
106 err_pubkey:
107 	X509_free(cert);
108 err_cert:
109 	fclose(f);
110 	return ret;
111 }
112 
113 /**
114  * rsa_engine_get_pub_key() - read a public key from given engine
115  *
116  * @keydir:	Key prefix
117  * @name	Name of key
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)
121  */
122 static int rsa_engine_get_pub_key(const char *keydir, const char *name,
123 				  ENGINE *engine, RSA **rsap)
124 {
125 	const char *engine_id;
126 	char key_id[1024];
127 	EVP_PKEY *key;
128 	RSA *rsa;
129 	int ret;
130 
131 	*rsap = NULL;
132 
133 	engine_id = ENGINE_get_id(engine);
134 
135 	if (engine_id && !strcmp(engine_id, "pkcs11")) {
136 		if (keydir)
137 			snprintf(key_id, sizeof(key_id),
138 				 "pkcs11:%s;object=%s;type=public",
139 				 keydir, name);
140 		else
141 			snprintf(key_id, sizeof(key_id),
142 				 "pkcs11:object=%s;type=public",
143 				 name);
144 	} else {
145 		fprintf(stderr, "Engine not supported\n");
146 		return -ENOTSUP;
147 	}
148 
149 	key = ENGINE_load_public_key(engine, key_id, NULL, NULL);
150 	if (!key)
151 		return rsa_err("Failure loading public key from engine");
152 
153 	/* Convert to a RSA_style key. */
154 	rsa = EVP_PKEY_get1_RSA(key);
155 	if (!rsa) {
156 		rsa_err("Couldn't convert to a RSA style key");
157 		ret = -EINVAL;
158 		goto err_rsa;
159 	}
160 
161 	EVP_PKEY_free(key);
162 	*rsap = rsa;
163 
164 	return 0;
165 
166 err_rsa:
167 	EVP_PKEY_free(key);
168 	return ret;
169 }
170 
171 /**
172  * rsa_get_pub_key() - read a public key
173  *
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)
179  */
180 static int rsa_get_pub_key(const char *keydir, const char *name,
181 			   ENGINE *engine, RSA **rsap)
182 {
183 	if (engine)
184 		return rsa_engine_get_pub_key(keydir, name, engine, rsap);
185 	return rsa_pem_get_pub_key(keydir, name, rsap);
186 }
187 
188 /**
189  * rsa_pem_get_priv_key() - read a private key from a .key file
190  *
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)
195  */
196 static int rsa_pem_get_priv_key(const char *keydir, const char *name,
197 				RSA **rsap)
198 {
199 	char path[1024];
200 	RSA *rsa;
201 	FILE *f;
202 
203 	*rsap = NULL;
204 	snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
205 	f = fopen(path, "r");
206 	if (!f) {
207 		fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
208 			path, strerror(errno));
209 		return -ENOENT;
210 	}
211 
212 	rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
213 	if (!rsa) {
214 		rsa_err("Failure reading private key");
215 		fclose(f);
216 		return -EPROTO;
217 	}
218 	fclose(f);
219 	*rsap = rsa;
220 
221 	return 0;
222 }
223 
224 /**
225  * rsa_engine_get_priv_key() - read a private key from given engine
226  *
227  * @keydir:	Key prefix
228  * @name	Name of key
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)
232  */
233 static int rsa_engine_get_priv_key(const char *keydir, const char *name,
234 				   ENGINE *engine, RSA **rsap)
235 {
236 	const char *engine_id;
237 	char key_id[1024];
238 	EVP_PKEY *key;
239 	RSA *rsa;
240 	int ret;
241 
242 	*rsap = NULL;
243 
244 	engine_id = ENGINE_get_id(engine);
245 
246 	if (engine_id && !strcmp(engine_id, "pkcs11")) {
247 		if (keydir)
248 			snprintf(key_id, sizeof(key_id),
249 				 "pkcs11:%s;object=%s;type=private",
250 				 keydir, name);
251 		else
252 			snprintf(key_id, sizeof(key_id),
253 				 "pkcs11:object=%s;type=private",
254 				 name);
255 	} else {
256 		fprintf(stderr, "Engine not supported\n");
257 		return -ENOTSUP;
258 	}
259 
260 	key = ENGINE_load_private_key(engine, key_id, NULL, NULL);
261 	if (!key)
262 		return rsa_err("Failure loading private key from engine");
263 
264 	/* Convert to a RSA_style key. */
265 	rsa = EVP_PKEY_get1_RSA(key);
266 	if (!rsa) {
267 		rsa_err("Couldn't convert to a RSA style key");
268 		ret = -EINVAL;
269 		goto err_rsa;
270 	}
271 
272 	EVP_PKEY_free(key);
273 	*rsap = rsa;
274 
275 	return 0;
276 
277 err_rsa:
278 	EVP_PKEY_free(key);
279 	return ret;
280 }
281 
282 /**
283  * rsa_get_priv_key() - read a private key
284  *
285  * @keydir:	Directory containing the key (PEM file) or key prefix (engine)
286  * @name	Name of key
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)
290  */
291 static int rsa_get_priv_key(const char *keydir, const char *name,
292 			    ENGINE *engine, RSA **rsap)
293 {
294 	if (engine)
295 		return rsa_engine_get_priv_key(keydir, name, engine, rsap);
296 	return rsa_pem_get_priv_key(keydir, name, rsap);
297 }
298 
299 static int rsa_init(void)
300 {
301 	int ret;
302 
303 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
304 	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
305 	ret = SSL_library_init();
306 #else
307 	ret = OPENSSL_init_ssl(0, NULL);
308 #endif
309 	if (!ret) {
310 		fprintf(stderr, "Failure to init SSL library\n");
311 		return -1;
312 	}
313 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
314 	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
315 	SSL_load_error_strings();
316 
317 	OpenSSL_add_all_algorithms();
318 	OpenSSL_add_all_digests();
319 	OpenSSL_add_all_ciphers();
320 #endif
321 
322 	return 0;
323 }
324 
325 static int rsa_engine_init(const char *engine_id, ENGINE **pe)
326 {
327 	ENGINE *e;
328 	int ret;
329 
330 	ENGINE_load_builtin_engines();
331 
332 	e = ENGINE_by_id(engine_id);
333 	if (!e) {
334 		fprintf(stderr, "Engine isn't available\n");
335 		ret = -1;
336 		goto err_engine_by_id;
337 	}
338 
339 	if (!ENGINE_init(e)) {
340 		fprintf(stderr, "Couldn't initialize engine\n");
341 		ret = -1;
342 		goto err_engine_init;
343 	}
344 
345 	if (!ENGINE_set_default_RSA(e)) {
346 		fprintf(stderr, "Couldn't set engine as default for RSA\n");
347 		ret = -1;
348 		goto err_set_rsa;
349 	}
350 
351 	*pe = e;
352 
353 	return 0;
354 
355 err_set_rsa:
356 	ENGINE_finish(e);
357 err_engine_init:
358 	ENGINE_free(e);
359 err_engine_by_id:
360 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
361 	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
362 	ENGINE_cleanup();
363 #endif
364 	return ret;
365 }
366 
367 static void rsa_remove(void)
368 {
369 #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
370 	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
371 	CRYPTO_cleanup_all_ex_data();
372 	ERR_free_strings();
373 #ifdef HAVE_ERR_REMOVE_THREAD_STATE
374 	ERR_remove_thread_state(NULL);
375 #else
376 	ERR_remove_state(0);
377 #endif
378 	EVP_cleanup();
379 #endif
380 }
381 
382 static void rsa_engine_remove(ENGINE *e)
383 {
384 	if (e) {
385 		ENGINE_finish(e);
386 		ENGINE_free(e);
387 	}
388 }
389 
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)
394 {
395 	EVP_PKEY *key;
396 	EVP_PKEY_CTX *ckey;
397 	EVP_MD_CTX *context;
398 	int ret = 0;
399 	size_t size;
400 	uint8_t *sig;
401 	int i;
402 
403 	key = EVP_PKEY_new();
404 	if (!key)
405 		return rsa_err("EVP_PKEY object creation failed");
406 
407 	if (!EVP_PKEY_set1_RSA(key, rsa)) {
408 		ret = rsa_err("EVP key setup failed");
409 		goto err_set;
410 	}
411 
412 	size = EVP_PKEY_size(key);
413 	sig = malloc(size);
414 	if (!sig) {
415 		fprintf(stderr, "Out of memory for signature (%zu bytes)\n",
416 			size);
417 		ret = -ENOMEM;
418 		goto err_alloc;
419 	}
420 
421 	context = EVP_MD_CTX_create();
422 	if (!context) {
423 		ret = rsa_err("EVP context creation failed");
424 		goto err_create;
425 	}
426 	EVP_MD_CTX_init(context);
427 
428 	ckey = EVP_PKEY_CTX_new(key, NULL);
429 	if (!ckey) {
430 		ret = rsa_err("EVP key context creation failed");
431 		goto err_create;
432 	}
433 
434 	if (EVP_DigestSignInit(context, &ckey,
435 			       checksum_algo->calculate_sign(),
436 			       NULL, key) <= 0) {
437 		ret = rsa_err("Signer setup failed");
438 		goto err_sign;
439 	}
440 
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");
446 			goto err_sign;
447 		}
448 	}
449 #endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
450 
451 	for (i = 0; i < region_count; i++) {
452 		if (!EVP_DigestSignUpdate(context, region[i].data,
453 					  region[i].size)) {
454 			ret = rsa_err("Signing data failed");
455 			goto err_sign;
456 		}
457 	}
458 
459 	if (!EVP_DigestSignFinal(context, sig, &size)) {
460 		ret = rsa_err("Could not obtain signature");
461 		goto err_sign;
462 	}
463 
464 	#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
465 		(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
466 		EVP_MD_CTX_cleanup(context);
467 	#else
468 		EVP_MD_CTX_reset(context);
469 	#endif
470 	EVP_MD_CTX_destroy(context);
471 	EVP_PKEY_free(key);
472 
473 	debug("Got signature: %d bytes, expected %zu\n", *sig_size, size);
474 	*sigp = sig;
475 	*sig_size = size;
476 
477 	return 0;
478 
479 err_sign:
480 	EVP_MD_CTX_destroy(context);
481 err_create:
482 	free(sig);
483 err_alloc:
484 err_set:
485 	EVP_PKEY_free(key);
486 	return ret;
487 }
488 
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)
492 {
493 	RSA *rsa;
494 	ENGINE *e = NULL;
495 	int ret;
496 
497 	ret = rsa_init();
498 	if (ret)
499 		return ret;
500 
501 	if (info->engine_id) {
502 		ret = rsa_engine_init(info->engine_id, &e);
503 		if (ret)
504 			goto err_engine;
505 	}
506 
507 	ret = rsa_get_priv_key(info->keydir, info->keyname, e, &rsa);
508 	if (ret)
509 		goto err_priv;
510 	ret = rsa_sign_with_key(rsa, info->padding, info->checksum, region,
511 				region_count, sigp, sig_len);
512 	if (ret)
513 		goto err_sign;
514 
515 	RSA_free(rsa);
516 	if (info->engine_id)
517 		rsa_engine_remove(e);
518 	rsa_remove();
519 
520 	return ret;
521 
522 err_sign:
523 	RSA_free(rsa);
524 err_priv:
525 	if (info->engine_id)
526 		rsa_engine_remove(e);
527 err_engine:
528 	rsa_remove();
529 	return ret;
530 }
531 
532 /*
533  * rsa_get_exponent(): - Get the public exponent from an RSA key
534  */
535 static int rsa_get_exponent(RSA *key, uint64_t *e)
536 {
537 	int ret;
538 	BIGNUM *bn_te;
539 	const BIGNUM *key_e;
540 	uint64_t te;
541 
542 	ret = -EINVAL;
543 	bn_te = NULL;
544 
545 	if (!e)
546 		goto cleanup;
547 
548 	RSA_get0_key(key, NULL, &key_e, NULL);
549 	if (BN_num_bits(key_e) > 64)
550 		goto cleanup;
551 
552 	*e = BN_get_word(key_e);
553 
554 	if (BN_num_bits(key_e) < 33) {
555 		ret = 0;
556 		goto cleanup;
557 	}
558 
559 	bn_te = BN_dup(key_e);
560 	if (!bn_te)
561 		goto cleanup;
562 
563 	if (!BN_rshift(bn_te, bn_te, 32))
564 		goto cleanup;
565 
566 	if (!BN_mask_bits(bn_te, 32))
567 		goto cleanup;
568 
569 	te = BN_get_word(bn_te);
570 	te <<= 32;
571 	*e |= te;
572 	ret = 0;
573 
574 cleanup:
575 	if (bn_te)
576 		BN_free(bn_te);
577 
578 	return ret;
579 }
580 
581 /*
582  * rsa_get_params(): - Get the important parameters of an RSA public key
583  */
584 int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
585 		   BIGNUM **modulusp, BIGNUM **r_squaredp)
586 {
587 	BIGNUM *big1, *big2, *big32, *big2_32;
588 	BIGNUM *n, *r, *r_squared, *tmp;
589 	const BIGNUM *key_n;
590 	BN_CTX *bn_ctx = BN_CTX_new();
591 	int ret = 0;
592 
593 	/* Initialize BIGNUMs */
594 	big1 = BN_new();
595 	big2 = BN_new();
596 	big32 = BN_new();
597 	r = BN_new();
598 	r_squared = BN_new();
599 	tmp = BN_new();
600 	big2_32 = BN_new();
601 	n = BN_new();
602 	if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
603 	    !n) {
604 		fprintf(stderr, "Out of memory (bignum)\n");
605 		return -ENOMEM;
606 	}
607 
608 	if (0 != rsa_get_exponent(key, exponent))
609 		ret = -1;
610 
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))
614 		ret = -1;
615 
616 	/* big2_32 = 2^32 */
617 	if (!BN_exp(big2_32, big2, big32, bn_ctx))
618 		ret = -1;
619 
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))
623 		ret = -1;
624 	*n0_invp = BN_get_word(tmp);
625 
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))
629 		ret = -1;
630 
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))
635 		ret = -1;
636 
637 	*modulusp = n;
638 	*r_squaredp = r_squared;
639 
640 	BN_free(big1);
641 	BN_free(big2);
642 	BN_free(big32);
643 	BN_free(r);
644 	BN_free(tmp);
645 	BN_free(big2_32);
646 	if (ret) {
647 		fprintf(stderr, "Bignum operations failed\n");
648 		return -ENOMEM;
649 	}
650 
651 	return ret;
652 }
653 
654 static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
655 			  BIGNUM *num, int num_bits)
656 {
657 	int nwords = num_bits / 32;
658 	int size;
659 	uint32_t *buf, *ptr;
660 	BIGNUM *tmp, *big2, *big32, *big2_32;
661 	BN_CTX *ctx;
662 	int ret;
663 
664 	tmp = BN_new();
665 	big2 = BN_new();
666 	big32 = BN_new();
667 	big2_32 = BN_new();
668 
669 	/*
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.
676 	 */
677 	if (!tmp || !big2 || !big32 || !big2_32) {
678 		fprintf(stderr, "Out of memory (bignum)\n");
679 		return -ENOMEM;
680 	}
681 	ctx = BN_CTX_new();
682 	if (!tmp) {
683 		fprintf(stderr, "Out of memory (bignum context)\n");
684 		return -ENOMEM;
685 	}
686 	BN_set_word(big2, 2L);
687 	BN_set_word(big32, 32L);
688 	BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
689 
690 	size = nwords * sizeof(uint32_t);
691 	buf = malloc(size);
692 	if (!buf) {
693 		fprintf(stderr, "Out of memory (%d bytes)\n", size);
694 		return -ENOMEM;
695 	}
696 
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 */
702 	}
703 
704 	/*
705 	 * We try signing with successively increasing size values, so this
706 	 * might fail several times
707 	 */
708 	ret = fdt_setprop(blob, noffset, prop_name, buf, size);
709 	free(buf);
710 	BN_free(tmp);
711 	BN_free(big2);
712 	BN_free(big32);
713 	BN_free(big2_32);
714 
715 	return ret ? -FDT_ERR_NOSPACE : 0;
716 }
717 
718 int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
719 {
720 	BIGNUM *modulus, *r_squared;
721 	uint64_t exponent;
722 	uint32_t n0_inv;
723 	int parent, node;
724 	char name[100];
725 	int ret;
726 	int bits;
727 	RSA *rsa;
728 	ENGINE *e = NULL;
729 
730 	debug("%s: Getting verification data\n", __func__);
731 	if (info->engine_id) {
732 		ret = rsa_engine_init(info->engine_id, &e);
733 		if (ret)
734 			return ret;
735 	}
736 	ret = rsa_get_pub_key(info->keydir, info->keyname, e, &rsa);
737 	if (ret)
738 		goto err_get_pub_key;
739 	ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
740 	if (ret)
741 		goto err_get_params;
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);
746 		if (parent < 0) {
747 			ret = parent;
748 			if (ret != -FDT_ERR_NOSPACE) {
749 				fprintf(stderr, "Couldn't create signature node: %s\n",
750 					fdt_strerror(parent));
751 			}
752 		}
753 	}
754 	if (ret)
755 		goto done;
756 
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);
762 		if (node < 0) {
763 			ret = node;
764 			if (ret != -FDT_ERR_NOSPACE) {
765 				fprintf(stderr, "Could not create key subnode: %s\n",
766 					fdt_strerror(node));
767 			}
768 		}
769 	} else if (node < 0) {
770 		fprintf(stderr, "Cannot select keys parent: %s\n",
771 			fdt_strerror(node));
772 		ret = node;
773 	}
774 
775 	if (!ret) {
776 		ret = fdt_setprop_string(keydest, node, "key-name-hint",
777 				 info->keyname);
778 	}
779 	if (!ret)
780 		ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
781 	if (!ret)
782 		ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
783 	if (!ret) {
784 		ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
785 	}
786 	if (!ret) {
787 		ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
788 				     bits);
789 	}
790 	if (!ret) {
791 		ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
792 				     bits);
793 	}
794 	if (!ret) {
795 		ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
796 					 info->name);
797 	}
798 	if (!ret && info->require_keys) {
799 		ret = fdt_setprop_string(keydest, node, "required",
800 					 info->require_keys);
801 	}
802 done:
803 	BN_free(modulus);
804 	BN_free(r_squared);
805 	if (ret)
806 		ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
807 err_get_params:
808 	RSA_free(rsa);
809 err_get_pub_key:
810 	if (info->engine_id)
811 		rsa_engine_remove(e);
812 
813 	return ret;
814 }
815