1 /* 2 * Copyright (c) 2013, Google Inc. 3 * 4 * SPDX-License-Identifier: GPL-2.0+ 5 */ 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 22 static 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 * rsa_get_pub_key() - read a public key from a .crt file 35 * 36 * @keydir: Directory containins the key 37 * @name Name of key file (will have a .crt extension) 38 * @rsap Returns RSA object, or NULL on failure 39 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 40 */ 41 static 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 /* Read the certificate */ 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 /* Get the public key from the certificate. */ 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 /* Convert to a RSA_style key. */ 76 rsa = EVP_PKEY_get1_RSA(key); 77 if (!rsa) { 78 rsa_err("Couldn't convert to a RSA style key"); 79 goto err_rsa; 80 } 81 fclose(f); 82 EVP_PKEY_free(key); 83 X509_free(cert); 84 *rsap = rsa; 85 86 return 0; 87 88 err_rsa: 89 EVP_PKEY_free(key); 90 err_pubkey: 91 X509_free(cert); 92 err_cert: 93 fclose(f); 94 return ret; 95 } 96 97 /** 98 * rsa_get_priv_key() - read a private key from a .key file 99 * 100 * @keydir: Directory containins the key 101 * @name Name of key file (will have a .key extension) 102 * @rsap Returns RSA object, or NULL on failure 103 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 104 */ 105 static int rsa_get_priv_key(const char *keydir, const char *name, RSA **rsap) 106 { 107 char path[1024]; 108 RSA *rsa; 109 FILE *f; 110 111 *rsap = NULL; 112 snprintf(path, sizeof(path), "%s/%s.key", keydir, name); 113 f = fopen(path, "r"); 114 if (!f) { 115 fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n", 116 path, strerror(errno)); 117 return -ENOENT; 118 } 119 120 rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path); 121 if (!rsa) { 122 rsa_err("Failure reading private key"); 123 fclose(f); 124 return -EPROTO; 125 } 126 fclose(f); 127 *rsap = rsa; 128 129 return 0; 130 } 131 132 static int rsa_init(void) 133 { 134 int ret; 135 136 ret = SSL_library_init(); 137 if (!ret) { 138 fprintf(stderr, "Failure to init SSL library\n"); 139 return -1; 140 } 141 SSL_load_error_strings(); 142 143 OpenSSL_add_all_algorithms(); 144 OpenSSL_add_all_digests(); 145 OpenSSL_add_all_ciphers(); 146 147 return 0; 148 } 149 150 static void rsa_remove(void) 151 { 152 CRYPTO_cleanup_all_ex_data(); 153 ERR_free_strings(); 154 #ifdef HAVE_ERR_REMOVE_THREAD_STATE 155 ERR_remove_thread_state(NULL); 156 #else 157 ERR_remove_state(0); 158 #endif 159 EVP_cleanup(); 160 } 161 162 static int rsa_sign_with_key(RSA *rsa, const struct image_region region[], 163 int region_count, uint8_t **sigp, uint *sig_size) 164 { 165 EVP_PKEY *key; 166 EVP_MD_CTX *context; 167 int size, ret = 0; 168 uint8_t *sig; 169 int i; 170 171 key = EVP_PKEY_new(); 172 if (!key) 173 return rsa_err("EVP_PKEY object creation failed"); 174 175 if (!EVP_PKEY_set1_RSA(key, rsa)) { 176 ret = rsa_err("EVP key setup failed"); 177 goto err_set; 178 } 179 180 size = EVP_PKEY_size(key); 181 sig = malloc(size); 182 if (!sig) { 183 fprintf(stderr, "Out of memory for signature (%d bytes)\n", 184 size); 185 ret = -ENOMEM; 186 goto err_alloc; 187 } 188 189 context = EVP_MD_CTX_create(); 190 if (!context) { 191 ret = rsa_err("EVP context creation failed"); 192 goto err_create; 193 } 194 EVP_MD_CTX_init(context); 195 if (!EVP_SignInit(context, EVP_sha1())) { 196 ret = rsa_err("Signer setup failed"); 197 goto err_sign; 198 } 199 200 for (i = 0; i < region_count; i++) { 201 if (!EVP_SignUpdate(context, region[i].data, region[i].size)) { 202 ret = rsa_err("Signing data failed"); 203 goto err_sign; 204 } 205 } 206 207 if (!EVP_SignFinal(context, sig, sig_size, key)) { 208 ret = rsa_err("Could not obtain signature"); 209 goto err_sign; 210 } 211 EVP_MD_CTX_cleanup(context); 212 EVP_MD_CTX_destroy(context); 213 EVP_PKEY_free(key); 214 215 debug("Got signature: %d bytes, expected %d\n", *sig_size, size); 216 *sigp = sig; 217 *sig_size = size; 218 219 return 0; 220 221 err_sign: 222 EVP_MD_CTX_destroy(context); 223 err_create: 224 free(sig); 225 err_alloc: 226 err_set: 227 EVP_PKEY_free(key); 228 return ret; 229 } 230 231 int rsa_sign(struct image_sign_info *info, 232 const struct image_region region[], int region_count, 233 uint8_t **sigp, uint *sig_len) 234 { 235 RSA *rsa; 236 int ret; 237 238 ret = rsa_init(); 239 if (ret) 240 return ret; 241 242 ret = rsa_get_priv_key(info->keydir, info->keyname, &rsa); 243 if (ret) 244 goto err_priv; 245 ret = rsa_sign_with_key(rsa, region, region_count, sigp, sig_len); 246 if (ret) 247 goto err_sign; 248 249 RSA_free(rsa); 250 rsa_remove(); 251 252 return ret; 253 254 err_sign: 255 RSA_free(rsa); 256 err_priv: 257 rsa_remove(); 258 return ret; 259 } 260 261 /* 262 * rsa_get_params(): - Get the important parameters of an RSA public key 263 */ 264 int rsa_get_params(RSA *key, uint32_t *n0_invp, BIGNUM **modulusp, 265 BIGNUM **r_squaredp) 266 { 267 BIGNUM *big1, *big2, *big32, *big2_32; 268 BIGNUM *n, *r, *r_squared, *tmp; 269 BN_CTX *bn_ctx = BN_CTX_new(); 270 int ret = 0; 271 272 /* Initialize BIGNUMs */ 273 big1 = BN_new(); 274 big2 = BN_new(); 275 big32 = BN_new(); 276 r = BN_new(); 277 r_squared = BN_new(); 278 tmp = BN_new(); 279 big2_32 = BN_new(); 280 n = BN_new(); 281 if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 || 282 !n) { 283 fprintf(stderr, "Out of memory (bignum)\n"); 284 return -ENOMEM; 285 } 286 287 if (!BN_copy(n, key->n) || !BN_set_word(big1, 1L) || 288 !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L)) 289 ret = -1; 290 291 /* big2_32 = 2^32 */ 292 if (!BN_exp(big2_32, big2, big32, bn_ctx)) 293 ret = -1; 294 295 /* Calculate n0_inv = -1 / n[0] mod 2^32 */ 296 if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) || 297 !BN_sub(tmp, big2_32, tmp)) 298 ret = -1; 299 *n0_invp = BN_get_word(tmp); 300 301 /* Calculate R = 2^(# of key bits) */ 302 if (!BN_set_word(tmp, BN_num_bits(n)) || 303 !BN_exp(r, big2, tmp, bn_ctx)) 304 ret = -1; 305 306 /* Calculate r_squared = R^2 mod n */ 307 if (!BN_copy(r_squared, r) || 308 !BN_mul(tmp, r_squared, r, bn_ctx) || 309 !BN_mod(r_squared, tmp, n, bn_ctx)) 310 ret = -1; 311 312 *modulusp = n; 313 *r_squaredp = r_squared; 314 315 BN_free(big1); 316 BN_free(big2); 317 BN_free(big32); 318 BN_free(r); 319 BN_free(tmp); 320 BN_free(big2_32); 321 if (ret) { 322 fprintf(stderr, "Bignum operations failed\n"); 323 return -ENOMEM; 324 } 325 326 return ret; 327 } 328 329 static int fdt_add_bignum(void *blob, int noffset, const char *prop_name, 330 BIGNUM *num, int num_bits) 331 { 332 int nwords = num_bits / 32; 333 int size; 334 uint32_t *buf, *ptr; 335 BIGNUM *tmp, *big2, *big32, *big2_32; 336 BN_CTX *ctx; 337 int ret; 338 339 tmp = BN_new(); 340 big2 = BN_new(); 341 big32 = BN_new(); 342 big2_32 = BN_new(); 343 if (!tmp || !big2 || !big32 || !big2_32) { 344 fprintf(stderr, "Out of memory (bignum)\n"); 345 return -ENOMEM; 346 } 347 ctx = BN_CTX_new(); 348 if (!tmp) { 349 fprintf(stderr, "Out of memory (bignum context)\n"); 350 return -ENOMEM; 351 } 352 BN_set_word(big2, 2L); 353 BN_set_word(big32, 32L); 354 BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */ 355 356 size = nwords * sizeof(uint32_t); 357 buf = malloc(size); 358 if (!buf) { 359 fprintf(stderr, "Out of memory (%d bytes)\n", size); 360 return -ENOMEM; 361 } 362 363 /* Write out modulus as big endian array of integers */ 364 for (ptr = buf + nwords - 1; ptr >= buf; ptr--) { 365 BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */ 366 *ptr = cpu_to_fdt32(BN_get_word(tmp)); 367 BN_rshift(num, num, 32); /* N = N/B */ 368 } 369 370 ret = fdt_setprop(blob, noffset, prop_name, buf, size); 371 if (ret) { 372 fprintf(stderr, "Failed to write public key to FIT\n"); 373 return -ENOSPC; 374 } 375 free(buf); 376 BN_free(tmp); 377 BN_free(big2); 378 BN_free(big32); 379 BN_free(big2_32); 380 381 return ret; 382 } 383 384 int rsa_add_verify_data(struct image_sign_info *info, void *keydest) 385 { 386 BIGNUM *modulus, *r_squared; 387 uint32_t n0_inv; 388 int parent, node; 389 char name[100]; 390 int ret; 391 int bits; 392 RSA *rsa; 393 394 debug("%s: Getting verification data\n", __func__); 395 ret = rsa_get_pub_key(info->keydir, info->keyname, &rsa); 396 if (ret) 397 return ret; 398 ret = rsa_get_params(rsa, &n0_inv, &modulus, &r_squared); 399 if (ret) 400 return ret; 401 bits = BN_num_bits(modulus); 402 parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME); 403 if (parent == -FDT_ERR_NOTFOUND) { 404 parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME); 405 if (parent < 0) { 406 fprintf(stderr, "Couldn't create signature node: %s\n", 407 fdt_strerror(parent)); 408 return -EINVAL; 409 } 410 } 411 412 /* Either create or overwrite the named key node */ 413 snprintf(name, sizeof(name), "key-%s", info->keyname); 414 node = fdt_subnode_offset(keydest, parent, name); 415 if (node == -FDT_ERR_NOTFOUND) { 416 node = fdt_add_subnode(keydest, parent, name); 417 if (node < 0) { 418 fprintf(stderr, "Could not create key subnode: %s\n", 419 fdt_strerror(node)); 420 return -EINVAL; 421 } 422 } else if (node < 0) { 423 fprintf(stderr, "Cannot select keys parent: %s\n", 424 fdt_strerror(node)); 425 return -ENOSPC; 426 } 427 428 ret = fdt_setprop_string(keydest, node, "key-name-hint", 429 info->keyname); 430 ret |= fdt_setprop_u32(keydest, node, "rsa,num-bits", bits); 431 ret |= fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv); 432 ret |= fdt_add_bignum(keydest, node, "rsa,modulus", modulus, bits); 433 ret |= fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared, bits); 434 ret |= fdt_setprop_string(keydest, node, FIT_ALGO_PROP, 435 info->algo->name); 436 if (info->require_keys) { 437 fdt_setprop_string(keydest, node, "required", 438 info->require_keys); 439 } 440 BN_free(modulus); 441 BN_free(r_squared); 442 if (ret) 443 return -EIO; 444 445 return 0; 446 } 447