1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (c) 2013, Google Inc.
4 */
5
6 #ifndef USE_HOSTCC
7 #include <common.h>
8 #include <fdtdec.h>
9 #include <log.h>
10 #include <malloc.h>
11 #include <asm/types.h>
12 #include <asm/byteorder.h>
13 #include <linux/errno.h>
14 #include <asm/types.h>
15 #include <asm/unaligned.h>
16 #include <dm.h>
17 #else
18 #include "fdt_host.h"
19 #include "mkimage.h"
20 #include <fdt_support.h>
21 #endif
22 #include <linux/kconfig.h>
23 #include <u-boot/rsa-mod-exp.h>
24 #include <u-boot/rsa.h>
25
26 #ifndef __UBOOT__
27 /*
28 * NOTE:
29 * Since host tools, like mkimage, make use of openssl library for
30 * RSA encryption, rsa_verify_with_pkey()/rsa_gen_key_prop() are
31 * of no use and should not be compiled in.
32 * So just turn off CONFIG_RSA_VERIFY_WITH_PKEY.
33 */
34
35 #undef CONFIG_RSA_VERIFY_WITH_PKEY
36 #endif
37
38 /* Default public exponent for backward compatibility */
39 #define RSA_DEFAULT_PUBEXP 65537
40
41 /**
42 * rsa_verify_padding() - Verify RSA message padding is valid
43 *
44 * Verify a RSA message's padding is consistent with PKCS1.5
45 * padding as described in the RSA PKCS#1 v2.1 standard.
46 *
47 * @msg: Padded message
48 * @pad_len: Number of expected padding bytes
49 * @algo: Checksum algo structure having information on DER encoding etc.
50 * @return 0 on success, != 0 on failure
51 */
rsa_verify_padding(const uint8_t * msg,const int pad_len,struct checksum_algo * algo)52 static int rsa_verify_padding(const uint8_t *msg, const int pad_len,
53 struct checksum_algo *algo)
54 {
55 int ff_len;
56 int ret;
57
58 /* first byte must be 0x00 */
59 ret = *msg++;
60 /* second byte must be 0x01 */
61 ret |= *msg++ ^ 0x01;
62 /* next ff_len bytes must be 0xff */
63 ff_len = pad_len - algo->der_len - 3;
64 ret |= *msg ^ 0xff;
65 ret |= memcmp(msg, msg+1, ff_len-1);
66 msg += ff_len;
67 /* next byte must be 0x00 */
68 ret |= *msg++;
69 /* next der_len bytes must match der_prefix */
70 ret |= memcmp(msg, algo->der_prefix, algo->der_len);
71
72 return ret;
73 }
74
padding_pkcs_15_verify(struct image_sign_info * info,uint8_t * msg,int msg_len,const uint8_t * hash,int hash_len)75 int padding_pkcs_15_verify(struct image_sign_info *info,
76 uint8_t *msg, int msg_len,
77 const uint8_t *hash, int hash_len)
78 {
79 struct checksum_algo *checksum = info->checksum;
80 int ret, pad_len = msg_len - checksum->checksum_len;
81
82 /* Check pkcs1.5 padding bytes. */
83 ret = rsa_verify_padding(msg, pad_len, checksum);
84 if (ret) {
85 debug("In RSAVerify(): Padding check failed!\n");
86 return -EINVAL;
87 }
88
89 /* Check hash. */
90 if (memcmp((uint8_t *)msg + pad_len, hash, msg_len - pad_len)) {
91 debug("In RSAVerify(): Hash check failed!\n");
92 return -EACCES;
93 }
94
95 return 0;
96 }
97
98 #ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
u32_i2osp(uint32_t val,uint8_t * buf)99 static void u32_i2osp(uint32_t val, uint8_t *buf)
100 {
101 buf[0] = (uint8_t)((val >> 24) & 0xff);
102 buf[1] = (uint8_t)((val >> 16) & 0xff);
103 buf[2] = (uint8_t)((val >> 8) & 0xff);
104 buf[3] = (uint8_t)((val >> 0) & 0xff);
105 }
106
107 /**
108 * mask_generation_function1() - generate an octet string
109 *
110 * Generate an octet string used to check rsa signature.
111 * It use an input octet string and a hash function.
112 *
113 * @checksum: A Hash function
114 * @seed: Specifies an input variable octet string
115 * @seed_len: Size of the input octet string
116 * @output: Specifies the output octet string
117 * @output_len: Size of the output octet string
118 * @return 0 if the octet string was correctly generated, others on error
119 */
mask_generation_function1(struct checksum_algo * checksum,uint8_t * seed,int seed_len,uint8_t * output,int output_len)120 static int mask_generation_function1(struct checksum_algo *checksum,
121 uint8_t *seed, int seed_len,
122 uint8_t *output, int output_len)
123 {
124 struct image_region region[2];
125 int ret = 0, i, i_output = 0, region_count = 2;
126 uint32_t counter = 0;
127 uint8_t buf_counter[4], *tmp;
128 int hash_len = checksum->checksum_len;
129
130 memset(output, 0, output_len);
131
132 region[0].data = seed;
133 region[0].size = seed_len;
134 region[1].data = &buf_counter[0];
135 region[1].size = 4;
136
137 tmp = malloc(hash_len);
138 if (!tmp) {
139 debug("%s: can't allocate array tmp\n", __func__);
140 ret = -ENOMEM;
141 goto out;
142 }
143
144 while (i_output < output_len) {
145 u32_i2osp(counter, &buf_counter[0]);
146
147 ret = checksum->calculate(checksum->name,
148 region, region_count,
149 tmp);
150 if (ret < 0) {
151 debug("%s: Error in checksum calculation\n", __func__);
152 goto out;
153 }
154
155 i = 0;
156 while ((i_output < output_len) && (i < hash_len)) {
157 output[i_output] = tmp[i];
158 i_output++;
159 i++;
160 }
161
162 counter++;
163 }
164
165 out:
166 free(tmp);
167
168 return ret;
169 }
170
compute_hash_prime(struct checksum_algo * checksum,uint8_t * pad,int pad_len,uint8_t * hash,int hash_len,uint8_t * salt,int salt_len,uint8_t * hprime)171 static int compute_hash_prime(struct checksum_algo *checksum,
172 uint8_t *pad, int pad_len,
173 uint8_t *hash, int hash_len,
174 uint8_t *salt, int salt_len,
175 uint8_t *hprime)
176 {
177 struct image_region region[3];
178 int ret, region_count = 3;
179
180 region[0].data = pad;
181 region[0].size = pad_len;
182 region[1].data = hash;
183 region[1].size = hash_len;
184 region[2].data = salt;
185 region[2].size = salt_len;
186
187 ret = checksum->calculate(checksum->name, region, region_count, hprime);
188 if (ret < 0) {
189 debug("%s: Error in checksum calculation\n", __func__);
190 goto out;
191 }
192
193 out:
194 return ret;
195 }
196
197 /*
198 * padding_pss_verify() - verify the pss padding of a signature
199 *
200 * Only works with a rsa_pss_saltlen:-2 (default value) right now
201 * saltlen:-1 "set the salt length to the digest length" is currently
202 * not supported.
203 *
204 * @info: Specifies key and FIT information
205 * @msg: byte array of message, len equal to msg_len
206 * @msg_len: Message length
207 * @hash: Pointer to the expected hash
208 * @hash_len: Length of the hash
209 */
padding_pss_verify(struct image_sign_info * info,uint8_t * msg,int msg_len,const uint8_t * hash,int hash_len)210 int padding_pss_verify(struct image_sign_info *info,
211 uint8_t *msg, int msg_len,
212 const uint8_t *hash, int hash_len)
213 {
214 uint8_t *masked_db = NULL;
215 int masked_db_len = msg_len - hash_len - 1;
216 uint8_t *h = NULL, *hprime = NULL;
217 int h_len = hash_len;
218 uint8_t *db_mask = NULL;
219 int db_mask_len = masked_db_len;
220 uint8_t *db = NULL, *salt = NULL;
221 int db_len = masked_db_len, salt_len = msg_len - hash_len - 2;
222 uint8_t pad_zero[8] = { 0 };
223 int ret, i, leftmost_bits = 1;
224 uint8_t leftmost_mask;
225 struct checksum_algo *checksum = info->checksum;
226
227 /* first, allocate everything */
228 masked_db = malloc(masked_db_len);
229 h = malloc(h_len);
230 db_mask = malloc(db_mask_len);
231 db = malloc(db_len);
232 salt = malloc(salt_len);
233 hprime = malloc(hash_len);
234 if (!masked_db || !h || !db_mask || !db || !salt || !hprime) {
235 printf("%s: can't allocate some buffer\n", __func__);
236 ret = -ENOMEM;
237 goto out;
238 }
239
240 /* step 4: check if the last byte is 0xbc */
241 if (msg[msg_len - 1] != 0xbc) {
242 printf("%s: invalid pss padding (0xbc is missing)\n", __func__);
243 ret = -EINVAL;
244 goto out;
245 }
246
247 /* step 5 */
248 memcpy(masked_db, msg, masked_db_len);
249 memcpy(h, msg + masked_db_len, h_len);
250
251 /* step 6 */
252 leftmost_mask = (0xff >> (8 - leftmost_bits)) << (8 - leftmost_bits);
253 if (masked_db[0] & leftmost_mask) {
254 printf("%s: invalid pss padding ", __func__);
255 printf("(leftmost bit of maskedDB not zero)\n");
256 ret = -EINVAL;
257 goto out;
258 }
259
260 /* step 7 */
261 mask_generation_function1(checksum, h, h_len, db_mask, db_mask_len);
262
263 /* step 8 */
264 for (i = 0; i < db_len; i++)
265 db[i] = masked_db[i] ^ db_mask[i];
266
267 /* step 9 */
268 db[0] &= 0xff >> leftmost_bits;
269
270 /* step 10 */
271 if (db[0] != 0x01) {
272 printf("%s: invalid pss padding ", __func__);
273 printf("(leftmost byte of db isn't 0x01)\n");
274 ret = EINVAL;
275 goto out;
276 }
277
278 /* step 11 */
279 memcpy(salt, &db[1], salt_len);
280
281 /* step 12 & 13 */
282 compute_hash_prime(checksum, pad_zero, 8,
283 (uint8_t *)hash, hash_len,
284 salt, salt_len, hprime);
285
286 /* step 14 */
287 ret = memcmp(h, hprime, hash_len);
288
289 out:
290 free(hprime);
291 free(salt);
292 free(db);
293 free(db_mask);
294 free(h);
295 free(masked_db);
296
297 return ret;
298 }
299 #endif
300
301 #if CONFIG_IS_ENABLED(FIT_SIGNATURE) || CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY)
302 /**
303 * rsa_verify_key() - Verify a signature against some data using RSA Key
304 *
305 * Verify a RSA PKCS1.5 signature against an expected hash using
306 * the RSA Key properties in prop structure.
307 *
308 * @info: Specifies key and FIT information
309 * @prop: Specifies key
310 * @sig: Signature
311 * @sig_len: Number of bytes in signature
312 * @hash: Pointer to the expected hash
313 * @key_len: Number of bytes in rsa key
314 * @return 0 if verified, -ve on error
315 */
rsa_verify_key(struct image_sign_info * info,struct key_prop * prop,const uint8_t * sig,const uint32_t sig_len,const uint8_t * hash,const uint32_t key_len)316 static int rsa_verify_key(struct image_sign_info *info,
317 struct key_prop *prop, const uint8_t *sig,
318 const uint32_t sig_len, const uint8_t *hash,
319 const uint32_t key_len)
320 {
321 int ret;
322 #if !defined(USE_HOSTCC)
323 struct udevice *mod_exp_dev;
324 #endif
325 struct checksum_algo *checksum = info->checksum;
326 struct padding_algo *padding = info->padding;
327 int hash_len;
328
329 if (!prop || !sig || !hash || !checksum)
330 return -EIO;
331
332 if (sig_len != (prop->num_bits / 8)) {
333 debug("Signature is of incorrect length %d\n", sig_len);
334 return -EINVAL;
335 }
336
337 debug("Checksum algorithm: %s", checksum->name);
338
339 /* Sanity check for stack size */
340 if (sig_len > RSA_MAX_SIG_BITS / 8) {
341 debug("Signature length %u exceeds maximum %d\n", sig_len,
342 RSA_MAX_SIG_BITS / 8);
343 return -EINVAL;
344 }
345
346 uint8_t buf[sig_len];
347 hash_len = checksum->checksum_len;
348
349 #if !defined(USE_HOSTCC)
350 ret = uclass_get_device(UCLASS_MOD_EXP, 0, &mod_exp_dev);
351 if (ret) {
352 printf("RSA: Can't find Modular Exp implementation\n");
353 return -EINVAL;
354 }
355
356 ret = rsa_mod_exp(mod_exp_dev, sig, sig_len, prop, buf);
357 #else
358 ret = rsa_mod_exp_sw(sig, sig_len, prop, buf);
359 #endif
360 if (ret) {
361 debug("Error in Modular exponentation\n");
362 return ret;
363 }
364
365 ret = padding->verify(info, buf, key_len, hash, hash_len);
366 if (ret) {
367 debug("In RSAVerify(): padding check failed!\n");
368 return ret;
369 }
370
371 return 0;
372 }
373 #endif
374
375 #if CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY)
376 /**
377 * rsa_verify_with_pkey() - Verify a signature against some data using
378 * only modulus and exponent as RSA key properties.
379 * @info: Specifies key information
380 * @hash: Pointer to the expected hash
381 * @sig: Signature
382 * @sig_len: Number of bytes in signature
383 *
384 * Parse a RSA public key blob in DER format pointed to in @info and fill
385 * a key_prop structure with properties of the key. Then verify a RSA PKCS1.5
386 * signature against an expected hash using the calculated properties.
387 *
388 * Return 0 if verified, -ve on error
389 */
rsa_verify_with_pkey(struct image_sign_info * info,const void * hash,uint8_t * sig,uint sig_len)390 int rsa_verify_with_pkey(struct image_sign_info *info,
391 const void *hash, uint8_t *sig, uint sig_len)
392 {
393 struct key_prop *prop;
394 int ret;
395
396 /* Public key is self-described to fill key_prop */
397 ret = rsa_gen_key_prop(info->key, info->keylen, &prop);
398 if (ret) {
399 debug("Generating necessary parameter for decoding failed\n");
400 return ret;
401 }
402
403 ret = rsa_verify_key(info, prop, sig, sig_len, hash,
404 info->crypto->key_len);
405
406 rsa_free_key_prop(prop);
407
408 return ret;
409 }
410 #else
rsa_verify_with_pkey(struct image_sign_info * info,const void * hash,uint8_t * sig,uint sig_len)411 int rsa_verify_with_pkey(struct image_sign_info *info,
412 const void *hash, uint8_t *sig, uint sig_len)
413 {
414 return -EACCES;
415 }
416 #endif
417
418 #if CONFIG_IS_ENABLED(FIT_SIGNATURE)
419 /**
420 * rsa_verify_with_keynode() - Verify a signature against some data using
421 * information in node with prperties of RSA Key like modulus, exponent etc.
422 *
423 * Parse sign-node and fill a key_prop structure with properties of the
424 * key. Verify a RSA PKCS1.5 signature against an expected hash using
425 * the properties parsed
426 *
427 * @info: Specifies key and FIT information
428 * @hash: Pointer to the expected hash
429 * @sig: Signature
430 * @sig_len: Number of bytes in signature
431 * @node: Node having the RSA Key properties
432 * @return 0 if verified, -ve on error
433 */
rsa_verify_with_keynode(struct image_sign_info * info,const void * hash,uint8_t * sig,uint sig_len,int node)434 static int rsa_verify_with_keynode(struct image_sign_info *info,
435 const void *hash, uint8_t *sig,
436 uint sig_len, int node)
437 {
438 const void *blob = info->fdt_blob;
439 struct key_prop prop;
440 int length;
441 int ret = 0;
442 const char *algo;
443
444 if (node < 0) {
445 debug("%s: Skipping invalid node", __func__);
446 return -EBADF;
447 }
448
449 algo = fdt_getprop(blob, node, "algo", NULL);
450 if (strcmp(info->name, algo)) {
451 debug("%s: Wrong algo: have %s, expected %s", __func__,
452 info->name, algo);
453 return -EFAULT;
454 }
455
456 prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
457
458 prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
459
460 prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
461 if (!prop.public_exponent || length < sizeof(uint64_t))
462 prop.public_exponent = NULL;
463
464 prop.exp_len = sizeof(uint64_t);
465
466 prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
467
468 prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
469
470 if (!prop.num_bits || !prop.modulus || !prop.rr) {
471 debug("%s: Missing RSA key info", __func__);
472 return -EFAULT;
473 }
474
475 ret = rsa_verify_key(info, &prop, sig, sig_len, hash,
476 info->crypto->key_len);
477
478 return ret;
479 }
480 #else
rsa_verify_with_keynode(struct image_sign_info * info,const void * hash,uint8_t * sig,uint sig_len,int node)481 static int rsa_verify_with_keynode(struct image_sign_info *info,
482 const void *hash, uint8_t *sig,
483 uint sig_len, int node)
484 {
485 return -EACCES;
486 }
487 #endif
488
rsa_verify_hash(struct image_sign_info * info,const uint8_t * hash,uint8_t * sig,uint sig_len)489 int rsa_verify_hash(struct image_sign_info *info,
490 const uint8_t *hash, uint8_t *sig, uint sig_len)
491 {
492 int ret = -EACCES;
493
494 if (CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) && !info->fdt_blob) {
495 /* don't rely on fdt properties */
496 ret = rsa_verify_with_pkey(info, hash, sig, sig_len);
497
498 return ret;
499 }
500
501 if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) {
502 const void *blob = info->fdt_blob;
503 int ndepth, noffset;
504 int sig_node, node;
505 char name[100];
506
507 sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
508 if (sig_node < 0) {
509 debug("%s: No signature node found\n", __func__);
510 return -ENOENT;
511 }
512
513 /* See if we must use a particular key */
514 if (info->required_keynode != -1) {
515 ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
516 info->required_keynode);
517 return ret;
518 }
519
520 /* Look for a key that matches our hint */
521 snprintf(name, sizeof(name), "key-%s", info->keyname);
522 node = fdt_subnode_offset(blob, sig_node, name);
523 ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
524 if (!ret)
525 return ret;
526
527 /* No luck, so try each of the keys in turn */
528 for (ndepth = 0, noffset = fdt_next_node(blob, sig_node,
529 &ndepth);
530 (noffset >= 0) && (ndepth > 0);
531 noffset = fdt_next_node(blob, noffset, &ndepth)) {
532 if (ndepth == 1 && noffset != node) {
533 ret = rsa_verify_with_keynode(info, hash,
534 sig, sig_len,
535 noffset);
536 if (!ret)
537 break;
538 }
539 }
540 }
541
542 return ret;
543 }
544
rsa_verify(struct image_sign_info * info,const struct image_region region[],int region_count,uint8_t * sig,uint sig_len)545 int rsa_verify(struct image_sign_info *info,
546 const struct image_region region[], int region_count,
547 uint8_t *sig, uint sig_len)
548 {
549 /* Reserve memory for maximum checksum-length */
550 uint8_t hash[info->crypto->key_len];
551 int ret;
552
553 /*
554 * Verify that the checksum-length does not exceed the
555 * rsa-signature-length
556 */
557 if (info->checksum->checksum_len >
558 info->crypto->key_len) {
559 debug("%s: invlaid checksum-algorithm %s for %s\n",
560 __func__, info->checksum->name, info->crypto->name);
561 return -EINVAL;
562 }
563
564 /* Calculate checksum with checksum-algorithm */
565 ret = info->checksum->calculate(info->checksum->name,
566 region, region_count, hash);
567 if (ret < 0) {
568 debug("%s: Error in checksum calculation\n", __func__);
569 return -EINVAL;
570 }
571
572 return rsa_verify_hash(info, hash, sig, sig_len);
573 }
574