1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (c) 2013, Google Inc.
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>
20 #include <fdt_support.h>
22 #include <linux/kconfig.h>
23 #include <u-boot/rsa-mod-exp.h>
24 #include <u-boot/rsa.h>
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.
35 #undef CONFIG_RSA_VERIFY_WITH_PKEY
38 /* Default public exponent for backward compatibility */
39 #define RSA_DEFAULT_PUBEXP 65537
42 * rsa_verify_padding() - Verify RSA message padding is valid
44 * Verify a RSA message's padding is consistent with PKCS1.5
45 * padding as described in the RSA PKCS#1 v2.1 standard.
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
52 static int rsa_verify_padding(const uint8_t *msg, const int pad_len,
53 struct checksum_algo *algo)
58 /* first byte must be 0x00 */
60 /* second byte must be 0x01 */
62 /* next ff_len bytes must be 0xff */
63 ff_len = pad_len - algo->der_len - 3;
65 ret |= memcmp(msg, msg+1, ff_len-1);
67 /* next byte must be 0x00 */
69 /* next der_len bytes must match der_prefix */
70 ret |= memcmp(msg, algo->der_prefix, algo->der_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)
79 struct checksum_algo *checksum = info->checksum;
80 int ret, pad_len = msg_len - checksum->checksum_len;
82 /* Check pkcs1.5 padding bytes. */
83 ret = rsa_verify_padding(msg, pad_len, checksum);
85 debug("In RSAVerify(): Padding check failed!\n");
90 if (memcmp((uint8_t *)msg + pad_len, hash, msg_len - pad_len)) {
91 debug("In RSAVerify(): Hash check failed!\n");
99 U_BOOT_PADDING_ALGO(pkcs_15) = {
101 .verify = padding_pkcs_15_verify,
105 #if CONFIG_IS_ENABLED(FIT_RSASSA_PSS)
106 static void u32_i2osp(uint32_t val, uint8_t *buf)
108 buf[0] = (uint8_t)((val >> 24) & 0xff);
109 buf[1] = (uint8_t)((val >> 16) & 0xff);
110 buf[2] = (uint8_t)((val >> 8) & 0xff);
111 buf[3] = (uint8_t)((val >> 0) & 0xff);
115 * mask_generation_function1() - generate an octet string
117 * Generate an octet string used to check rsa signature.
118 * It use an input octet string and a hash function.
120 * @checksum: A Hash function
121 * @seed: Specifies an input variable octet string
122 * @seed_len: Size of the input octet string
123 * @output: Specifies the output octet string
124 * @output_len: Size of the output octet string
125 * @return 0 if the octet string was correctly generated, others on error
127 static int mask_generation_function1(struct checksum_algo *checksum,
128 uint8_t *seed, int seed_len,
129 uint8_t *output, int output_len)
131 struct image_region region[2];
132 int ret = 0, i, i_output = 0, region_count = 2;
133 uint32_t counter = 0;
134 uint8_t buf_counter[4], *tmp;
135 int hash_len = checksum->checksum_len;
137 memset(output, 0, output_len);
139 region[0].data = seed;
140 region[0].size = seed_len;
141 region[1].data = &buf_counter[0];
144 tmp = malloc(hash_len);
146 debug("%s: can't allocate array tmp\n", __func__);
151 while (i_output < output_len) {
152 u32_i2osp(counter, &buf_counter[0]);
154 ret = checksum->calculate(checksum->name,
155 region, region_count,
158 debug("%s: Error in checksum calculation\n", __func__);
163 while ((i_output < output_len) && (i < hash_len)) {
164 output[i_output] = tmp[i];
178 static int compute_hash_prime(struct checksum_algo *checksum,
179 uint8_t *pad, int pad_len,
180 uint8_t *hash, int hash_len,
181 uint8_t *salt, int salt_len,
184 struct image_region region[3];
185 int ret, region_count = 3;
187 region[0].data = pad;
188 region[0].size = pad_len;
189 region[1].data = hash;
190 region[1].size = hash_len;
191 region[2].data = salt;
192 region[2].size = salt_len;
194 ret = checksum->calculate(checksum->name, region, region_count, hprime);
196 debug("%s: Error in checksum calculation\n", __func__);
205 * padding_pss_verify() - verify the pss padding of a signature
207 * Only works with a rsa_pss_saltlen:-2 (default value) right now
208 * saltlen:-1 "set the salt length to the digest length" is currently
211 * @info: Specifies key and FIT information
212 * @msg: byte array of message, len equal to msg_len
213 * @msg_len: Message length
214 * @hash: Pointer to the expected hash
215 * @hash_len: Length of the hash
217 int padding_pss_verify(struct image_sign_info *info,
218 uint8_t *msg, int msg_len,
219 const uint8_t *hash, int hash_len)
221 uint8_t *masked_db = NULL;
222 int masked_db_len = msg_len - hash_len - 1;
223 uint8_t *h = NULL, *hprime = NULL;
224 int h_len = hash_len;
225 uint8_t *db_mask = NULL;
226 int db_mask_len = masked_db_len;
227 uint8_t *db = NULL, *salt = NULL;
228 int db_len = masked_db_len, salt_len = msg_len - hash_len - 2;
229 uint8_t pad_zero[8] = { 0 };
230 int ret, i, leftmost_bits = 1;
231 uint8_t leftmost_mask;
232 struct checksum_algo *checksum = info->checksum;
234 /* first, allocate everything */
235 masked_db = malloc(masked_db_len);
237 db_mask = malloc(db_mask_len);
239 salt = malloc(salt_len);
240 hprime = malloc(hash_len);
241 if (!masked_db || !h || !db_mask || !db || !salt || !hprime) {
242 printf("%s: can't allocate some buffer\n", __func__);
247 /* step 4: check if the last byte is 0xbc */
248 if (msg[msg_len - 1] != 0xbc) {
249 printf("%s: invalid pss padding (0xbc is missing)\n", __func__);
255 memcpy(masked_db, msg, masked_db_len);
256 memcpy(h, msg + masked_db_len, h_len);
259 leftmost_mask = (0xff >> (8 - leftmost_bits)) << (8 - leftmost_bits);
260 if (masked_db[0] & leftmost_mask) {
261 printf("%s: invalid pss padding ", __func__);
262 printf("(leftmost bit of maskedDB not zero)\n");
268 mask_generation_function1(checksum, h, h_len, db_mask, db_mask_len);
271 for (i = 0; i < db_len; i++)
272 db[i] = masked_db[i] ^ db_mask[i];
275 db[0] &= 0xff >> leftmost_bits;
279 printf("%s: invalid pss padding ", __func__);
280 printf("(leftmost byte of db isn't 0x01)\n");
286 memcpy(salt, &db[1], salt_len);
289 compute_hash_prime(checksum, pad_zero, 8,
290 (uint8_t *)hash, hash_len,
291 salt, salt_len, hprime);
294 ret = memcmp(h, hprime, hash_len);
308 U_BOOT_PADDING_ALGO(pss) = {
310 .verify = padding_pss_verify,
317 * rsa_verify_key() - Verify a signature against some data using RSA Key
319 * Verify a RSA PKCS1.5 signature against an expected hash using
320 * the RSA Key properties in prop structure.
322 * @info: Specifies key and FIT information
323 * @prop: Specifies key
325 * @sig_len: Number of bytes in signature
326 * @hash: Pointer to the expected hash
327 * @key_len: Number of bytes in rsa key
328 * @return 0 if verified, -ve on error
330 static int rsa_verify_key(struct image_sign_info *info,
331 struct key_prop *prop, const uint8_t *sig,
332 const uint32_t sig_len, const uint8_t *hash,
333 const uint32_t key_len)
336 #if !defined(USE_HOSTCC)
337 struct udevice *mod_exp_dev;
339 struct checksum_algo *checksum = info->checksum;
340 struct padding_algo *padding = info->padding;
343 if (!prop || !sig || !hash || !checksum || !padding)
346 if (sig_len != (prop->num_bits / 8)) {
347 debug("Signature is of incorrect length %d\n", sig_len);
351 debug("Checksum algorithm: %s", checksum->name);
353 /* Sanity check for stack size */
354 if (sig_len > RSA_MAX_SIG_BITS / 8) {
355 debug("Signature length %u exceeds maximum %d\n", sig_len,
356 RSA_MAX_SIG_BITS / 8);
360 uint8_t buf[sig_len];
361 hash_len = checksum->checksum_len;
363 #if !defined(USE_HOSTCC)
364 ret = uclass_get_device(UCLASS_MOD_EXP, 0, &mod_exp_dev);
366 printf("RSA: Can't find Modular Exp implementation\n");
370 ret = rsa_mod_exp(mod_exp_dev, sig, sig_len, prop, buf);
372 ret = rsa_mod_exp_sw(sig, sig_len, prop, buf);
375 debug("Error in Modular exponentation\n");
379 ret = padding->verify(info, buf, key_len, hash, hash_len);
381 debug("In RSAVerify(): padding check failed!\n");
389 * rsa_verify_with_pkey() - Verify a signature against some data using
390 * only modulus and exponent as RSA key properties.
391 * @info: Specifies key information
392 * @hash: Pointer to the expected hash
394 * @sig_len: Number of bytes in signature
396 * Parse a RSA public key blob in DER format pointed to in @info and fill
397 * a key_prop structure with properties of the key. Then verify a RSA PKCS1.5
398 * signature against an expected hash using the calculated properties.
400 * Return 0 if verified, -ve on error
402 int rsa_verify_with_pkey(struct image_sign_info *info,
403 const void *hash, uint8_t *sig, uint sig_len)
405 struct key_prop *prop;
408 if (!CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY))
411 /* Public key is self-described to fill key_prop */
412 ret = rsa_gen_key_prop(info->key, info->keylen, &prop);
414 debug("Generating necessary parameter for decoding failed\n");
418 ret = rsa_verify_key(info, prop, sig, sig_len, hash,
419 info->crypto->key_len);
421 rsa_free_key_prop(prop);
426 #if CONFIG_IS_ENABLED(FIT_SIGNATURE)
428 * rsa_verify_with_keynode() - Verify a signature against some data using
429 * information in node with prperties of RSA Key like modulus, exponent etc.
431 * Parse sign-node and fill a key_prop structure with properties of the
432 * key. Verify a RSA PKCS1.5 signature against an expected hash using
433 * the properties parsed
435 * @info: Specifies key and FIT information
436 * @hash: Pointer to the expected hash
438 * @sig_len: Number of bytes in signature
439 * @node: Node having the RSA Key properties
440 * @return 0 if verified, -ve on error
442 static int rsa_verify_with_keynode(struct image_sign_info *info,
443 const void *hash, uint8_t *sig,
444 uint sig_len, int node)
446 const void *blob = info->fdt_blob;
447 struct key_prop prop;
453 debug("%s: Skipping invalid node", __func__);
457 algo = fdt_getprop(blob, node, "algo", NULL);
458 if (strcmp(info->name, algo)) {
459 debug("%s: Wrong algo: have %s, expected %s", __func__,
464 prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
466 prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
468 prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
469 if (!prop.public_exponent || length < sizeof(uint64_t))
470 prop.public_exponent = NULL;
472 prop.exp_len = sizeof(uint64_t);
474 prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
476 prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
478 if (!prop.num_bits || !prop.modulus || !prop.rr) {
479 debug("%s: Missing RSA key info", __func__);
483 ret = rsa_verify_key(info, &prop, sig, sig_len, hash,
484 info->crypto->key_len);
489 static int rsa_verify_with_keynode(struct image_sign_info *info,
490 const void *hash, uint8_t *sig,
491 uint sig_len, int node)
497 int rsa_verify_hash(struct image_sign_info *info,
498 const uint8_t *hash, uint8_t *sig, uint sig_len)
502 if (CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) && !info->fdt_blob) {
503 /* don't rely on fdt properties */
504 ret = rsa_verify_with_pkey(info, hash, sig, sig_len);
509 if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) {
510 const void *blob = info->fdt_blob;
515 sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
517 debug("%s: No signature node found\n", __func__);
521 /* See if we must use a particular key */
522 if (info->required_keynode != -1) {
523 ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
524 info->required_keynode);
528 /* Look for a key that matches our hint */
529 snprintf(name, sizeof(name), "key-%s", info->keyname);
530 node = fdt_subnode_offset(blob, sig_node, name);
531 ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
535 /* No luck, so try each of the keys in turn */
536 for (ndepth = 0, noffset = fdt_next_node(blob, sig_node,
538 (noffset >= 0) && (ndepth > 0);
539 noffset = fdt_next_node(blob, noffset, &ndepth)) {
540 if (ndepth == 1 && noffset != node) {
541 ret = rsa_verify_with_keynode(info, hash,
553 int rsa_verify(struct image_sign_info *info,
554 const struct image_region region[], int region_count,
555 uint8_t *sig, uint sig_len)
557 /* Reserve memory for maximum checksum-length */
558 uint8_t hash[info->crypto->key_len];
562 * Verify that the checksum-length does not exceed the
563 * rsa-signature-length
565 if (info->checksum->checksum_len >
566 info->crypto->key_len) {
567 debug("%s: invalid checksum-algorithm %s for %s\n",
568 __func__, info->checksum->name, info->crypto->name);
572 /* Calculate checksum with checksum-algorithm */
573 ret = info->checksum->calculate(info->checksum->name,
574 region, region_count, hash);
576 debug("%s: Error in checksum calculation\n", __func__);
580 return rsa_verify_hash(info, hash, sig, sig_len);
585 U_BOOT_CRYPTO_ALGO(rsa2048) = {
587 .key_len = RSA2048_BYTES,
588 .verify = rsa_verify,
591 U_BOOT_CRYPTO_ALGO(rsa4096) = {
593 .key_len = RSA4096_BYTES,
594 .verify = rsa_verify,