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6
7#include "mkimage.h"
8#include <stdio.h>
9#include <string.h>
10#include <image.h>
11#include <time.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
18#if OPENSSL_VERSION_NUMBER >= 0x10000000L
19#define HAVE_ERR_REMOVE_THREAD_STATE
20#endif
21
22static int rsa_err(const char *msg)
23{
24 unsigned long sslErr = ERR_get_error();
25
26 fprintf(stderr, "%s", msg);
27 fprintf(stderr, ": %s\n",
28 ERR_error_string(sslErr, 0));
29
30 return -1;
31}
32
33
34
35
36
37
38
39
40
41static int rsa_get_pub_key(const char *keydir, const char *name, RSA **rsap)
42{
43 char path[1024];
44 EVP_PKEY *key;
45 X509 *cert;
46 RSA *rsa;
47 FILE *f;
48 int ret;
49
50 *rsap = NULL;
51 snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
52 f = fopen(path, "r");
53 if (!f) {
54 fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
55 path, strerror(errno));
56 return -EACCES;
57 }
58
59
60 cert = NULL;
61 if (!PEM_read_X509(f, &cert, NULL, NULL)) {
62 rsa_err("Couldn't read certificate");
63 ret = -EINVAL;
64 goto err_cert;
65 }
66
67
68 key = X509_get_pubkey(cert);
69 if (!key) {
70 rsa_err("Couldn't read public key\n");
71 ret = -EINVAL;
72 goto err_pubkey;
73 }
74
75
76 rsa = EVP_PKEY_get1_RSA(key);
77 if (!rsa) {
78 rsa_err("Couldn't convert to a RSA style key");
79 ret = -EINVAL;
80 goto err_rsa;
81 }
82 fclose(f);
83 EVP_PKEY_free(key);
84 X509_free(cert);
85 *rsap = rsa;
86
87 return 0;
88
89err_rsa:
90 EVP_PKEY_free(key);
91err_pubkey:
92 X509_free(cert);
93err_cert:
94 fclose(f);
95 return ret;
96}
97
98
99
100
101
102
103
104
105
106static int rsa_get_priv_key(const char *keydir, const char *name, RSA **rsap)
107{
108 char path[1024];
109 RSA *rsa;
110 FILE *f;
111
112 *rsap = NULL;
113 snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
114 f = fopen(path, "r");
115 if (!f) {
116 fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
117 path, strerror(errno));
118 return -ENOENT;
119 }
120
121 rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
122 if (!rsa) {
123 rsa_err("Failure reading private key");
124 fclose(f);
125 return -EPROTO;
126 }
127 fclose(f);
128 *rsap = rsa;
129
130 return 0;
131}
132
133static int rsa_init(void)
134{
135 int ret;
136
137 ret = SSL_library_init();
138 if (!ret) {
139 fprintf(stderr, "Failure to init SSL library\n");
140 return -1;
141 }
142 SSL_load_error_strings();
143
144 OpenSSL_add_all_algorithms();
145 OpenSSL_add_all_digests();
146 OpenSSL_add_all_ciphers();
147
148 return 0;
149}
150
151static void rsa_remove(void)
152{
153 CRYPTO_cleanup_all_ex_data();
154 ERR_free_strings();
155#ifdef HAVE_ERR_REMOVE_THREAD_STATE
156 ERR_remove_thread_state(NULL);
157#else
158 ERR_remove_state(0);
159#endif
160 EVP_cleanup();
161}
162
163static int rsa_sign_with_key(RSA *rsa, struct checksum_algo *checksum_algo,
164 const struct image_region region[], int region_count,
165 uint8_t **sigp, uint *sig_size)
166{
167 EVP_PKEY *key;
168 EVP_MD_CTX *context;
169 int size, ret = 0;
170 uint8_t *sig;
171 int i;
172
173 key = EVP_PKEY_new();
174 if (!key)
175 return rsa_err("EVP_PKEY object creation failed");
176
177 if (!EVP_PKEY_set1_RSA(key, rsa)) {
178 ret = rsa_err("EVP key setup failed");
179 goto err_set;
180 }
181
182 size = EVP_PKEY_size(key);
183 sig = malloc(size);
184 if (!sig) {
185 fprintf(stderr, "Out of memory for signature (%d bytes)\n",
186 size);
187 ret = -ENOMEM;
188 goto err_alloc;
189 }
190
191 context = EVP_MD_CTX_create();
192 if (!context) {
193 ret = rsa_err("EVP context creation failed");
194 goto err_create;
195 }
196 EVP_MD_CTX_init(context);
197 if (!EVP_SignInit(context, checksum_algo->calculate_sign())) {
198 ret = rsa_err("Signer setup failed");
199 goto err_sign;
200 }
201
202 for (i = 0; i < region_count; i++) {
203 if (!EVP_SignUpdate(context, region[i].data, region[i].size)) {
204 ret = rsa_err("Signing data failed");
205 goto err_sign;
206 }
207 }
208
209 if (!EVP_SignFinal(context, sig, sig_size, key)) {
210 ret = rsa_err("Could not obtain signature");
211 goto err_sign;
212 }
213 EVP_MD_CTX_cleanup(context);
214 EVP_MD_CTX_destroy(context);
215 EVP_PKEY_free(key);
216
217 debug("Got signature: %d bytes, expected %d\n", *sig_size, size);
218 *sigp = sig;
219 *sig_size = size;
220
221 return 0;
222
223err_sign:
224 EVP_MD_CTX_destroy(context);
225err_create:
226 free(sig);
227err_alloc:
228err_set:
229 EVP_PKEY_free(key);
230 return ret;
231}
232
233int rsa_sign(struct image_sign_info *info,
234 const struct image_region region[], int region_count,
235 uint8_t **sigp, uint *sig_len)
236{
237 RSA *rsa;
238 int ret;
239
240 ret = rsa_init();
241 if (ret)
242 return ret;
243
244 ret = rsa_get_priv_key(info->keydir, info->keyname, &rsa);
245 if (ret)
246 goto err_priv;
247 ret = rsa_sign_with_key(rsa, info->algo->checksum, region,
248 region_count, sigp, sig_len);
249 if (ret)
250 goto err_sign;
251
252 RSA_free(rsa);
253 rsa_remove();
254
255 return ret;
256
257err_sign:
258 RSA_free(rsa);
259err_priv:
260 rsa_remove();
261 return ret;
262}
263
264
265
266
267static int rsa_get_exponent(RSA *key, uint64_t *e)
268{
269 int ret;
270 BIGNUM *bn_te;
271 uint64_t te;
272
273 ret = -EINVAL;
274 bn_te = NULL;
275
276 if (!e)
277 goto cleanup;
278
279 if (BN_num_bits(key->e) > 64)
280 goto cleanup;
281
282 *e = BN_get_word(key->e);
283
284 if (BN_num_bits(key->e) < 33) {
285 ret = 0;
286 goto cleanup;
287 }
288
289 bn_te = BN_dup(key->e);
290 if (!bn_te)
291 goto cleanup;
292
293 if (!BN_rshift(bn_te, bn_te, 32))
294 goto cleanup;
295
296 if (!BN_mask_bits(bn_te, 32))
297 goto cleanup;
298
299 te = BN_get_word(bn_te);
300 te <<= 32;
301 *e |= te;
302 ret = 0;
303
304cleanup:
305 if (bn_te)
306 BN_free(bn_te);
307
308 return ret;
309}
310
311
312
313
314int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
315 BIGNUM **modulusp, BIGNUM **r_squaredp)
316{
317 BIGNUM *big1, *big2, *big32, *big2_32;
318 BIGNUM *n, *r, *r_squared, *tmp;
319 BN_CTX *bn_ctx = BN_CTX_new();
320 int ret = 0;
321
322
323 big1 = BN_new();
324 big2 = BN_new();
325 big32 = BN_new();
326 r = BN_new();
327 r_squared = BN_new();
328 tmp = BN_new();
329 big2_32 = BN_new();
330 n = BN_new();
331 if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
332 !n) {
333 fprintf(stderr, "Out of memory (bignum)\n");
334 return -ENOMEM;
335 }
336
337 if (0 != rsa_get_exponent(key, exponent))
338 ret = -1;
339
340 if (!BN_copy(n, key->n) || !BN_set_word(big1, 1L) ||
341 !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
342 ret = -1;
343
344
345 if (!BN_exp(big2_32, big2, big32, bn_ctx))
346 ret = -1;
347
348
349 if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
350 !BN_sub(tmp, big2_32, tmp))
351 ret = -1;
352 *n0_invp = BN_get_word(tmp);
353
354
355 if (!BN_set_word(tmp, BN_num_bits(n)) ||
356 !BN_exp(r, big2, tmp, bn_ctx))
357 ret = -1;
358
359
360 if (!BN_copy(r_squared, r) ||
361 !BN_mul(tmp, r_squared, r, bn_ctx) ||
362 !BN_mod(r_squared, tmp, n, bn_ctx))
363 ret = -1;
364
365 *modulusp = n;
366 *r_squaredp = r_squared;
367
368 BN_free(big1);
369 BN_free(big2);
370 BN_free(big32);
371 BN_free(r);
372 BN_free(tmp);
373 BN_free(big2_32);
374 if (ret) {
375 fprintf(stderr, "Bignum operations failed\n");
376 return -ENOMEM;
377 }
378
379 return ret;
380}
381
382static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
383 BIGNUM *num, int num_bits)
384{
385 int nwords = num_bits / 32;
386 int size;
387 uint32_t *buf, *ptr;
388 BIGNUM *tmp, *big2, *big32, *big2_32;
389 BN_CTX *ctx;
390 int ret;
391
392 tmp = BN_new();
393 big2 = BN_new();
394 big32 = BN_new();
395 big2_32 = BN_new();
396 if (!tmp || !big2 || !big32 || !big2_32) {
397 fprintf(stderr, "Out of memory (bignum)\n");
398 return -ENOMEM;
399 }
400 ctx = BN_CTX_new();
401 if (!tmp) {
402 fprintf(stderr, "Out of memory (bignum context)\n");
403 return -ENOMEM;
404 }
405 BN_set_word(big2, 2L);
406 BN_set_word(big32, 32L);
407 BN_exp(big2_32, big2, big32, ctx);
408
409 size = nwords * sizeof(uint32_t);
410 buf = malloc(size);
411 if (!buf) {
412 fprintf(stderr, "Out of memory (%d bytes)\n", size);
413 return -ENOMEM;
414 }
415
416
417 for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
418 BN_mod(tmp, num, big2_32, ctx);
419 *ptr = cpu_to_fdt32(BN_get_word(tmp));
420 BN_rshift(num, num, 32);
421 }
422
423 ret = fdt_setprop(blob, noffset, prop_name, buf, size);
424 if (ret) {
425 fprintf(stderr, "Failed to write public key to FIT\n");
426 return -ENOSPC;
427 }
428 free(buf);
429 BN_free(tmp);
430 BN_free(big2);
431 BN_free(big32);
432 BN_free(big2_32);
433
434 return ret;
435}
436
437int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
438{
439 BIGNUM *modulus, *r_squared;
440 uint64_t exponent;
441 uint32_t n0_inv;
442 int parent, node;
443 char name[100];
444 int ret;
445 int bits;
446 RSA *rsa;
447
448 debug("%s: Getting verification data\n", __func__);
449 ret = rsa_get_pub_key(info->keydir, info->keyname, &rsa);
450 if (ret)
451 return ret;
452 ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
453 if (ret)
454 return ret;
455 bits = BN_num_bits(modulus);
456 parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
457 if (parent == -FDT_ERR_NOTFOUND) {
458 parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
459 if (parent < 0) {
460 ret = parent;
461 if (ret != -FDT_ERR_NOSPACE) {
462 fprintf(stderr, "Couldn't create signature node: %s\n",
463 fdt_strerror(parent));
464 }
465 }
466 }
467 if (ret)
468 goto done;
469
470
471 snprintf(name, sizeof(name), "key-%s", info->keyname);
472 node = fdt_subnode_offset(keydest, parent, name);
473 if (node == -FDT_ERR_NOTFOUND) {
474 node = fdt_add_subnode(keydest, parent, name);
475 if (node < 0) {
476 ret = node;
477 if (ret != -FDT_ERR_NOSPACE) {
478 fprintf(stderr, "Could not create key subnode: %s\n",
479 fdt_strerror(node));
480 }
481 }
482 } else if (node < 0) {
483 fprintf(stderr, "Cannot select keys parent: %s\n",
484 fdt_strerror(node));
485 ret = node;
486 }
487
488 if (!ret) {
489 ret = fdt_setprop_string(keydest, node, "key-name-hint",
490 info->keyname);
491 }
492 if (!ret)
493 ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
494 if (!ret)
495 ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
496 if (!ret) {
497 ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
498 }
499 if (!ret) {
500 ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
501 bits);
502 }
503 if (!ret) {
504 ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
505 bits);
506 }
507 if (!ret) {
508 ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
509 info->algo->name);
510 }
511 if (info->require_keys) {
512 ret = fdt_setprop_string(keydest, node, "required",
513 info->require_keys);
514 }
515done:
516 BN_free(modulus);
517 BN_free(r_squared);
518 if (ret)
519 return ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
520
521 return 0;
522}
523
