diff options
Diffstat (limited to 'roms/u-boot/lib/rsa/rsa-verify.c')
-rw-r--r-- | roms/u-boot/lib/rsa/rsa-verify.c | 573 |
1 files changed, 573 insertions, 0 deletions
diff --git a/roms/u-boot/lib/rsa/rsa-verify.c b/roms/u-boot/lib/rsa/rsa-verify.c new file mode 100644 index 000000000..aee76f42d --- /dev/null +++ b/roms/u-boot/lib/rsa/rsa-verify.c @@ -0,0 +1,573 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2013, Google Inc. + */ + +#ifndef USE_HOSTCC +#include <common.h> +#include <fdtdec.h> +#include <log.h> +#include <malloc.h> +#include <asm/types.h> +#include <asm/byteorder.h> +#include <linux/errno.h> +#include <asm/types.h> +#include <asm/unaligned.h> +#include <dm.h> +#else +#include "fdt_host.h" +#include "mkimage.h" +#include <fdt_support.h> +#endif +#include <linux/kconfig.h> +#include <u-boot/rsa-mod-exp.h> +#include <u-boot/rsa.h> + +#ifndef __UBOOT__ +/* + * NOTE: + * Since host tools, like mkimage, make use of openssl library for + * RSA encryption, rsa_verify_with_pkey()/rsa_gen_key_prop() are + * of no use and should not be compiled in. + * So just turn off CONFIG_RSA_VERIFY_WITH_PKEY. + */ + +#undef CONFIG_RSA_VERIFY_WITH_PKEY +#endif + +/* Default public exponent for backward compatibility */ +#define RSA_DEFAULT_PUBEXP 65537 + +/** + * rsa_verify_padding() - Verify RSA message padding is valid + * + * Verify a RSA message's padding is consistent with PKCS1.5 + * padding as described in the RSA PKCS#1 v2.1 standard. + * + * @msg: Padded message + * @pad_len: Number of expected padding bytes + * @algo: Checksum algo structure having information on DER encoding etc. + * @return 0 on success, != 0 on failure + */ +static int rsa_verify_padding(const uint8_t *msg, const int pad_len, + struct checksum_algo *algo) +{ + int ff_len; + int ret; + + /* first byte must be 0x00 */ + ret = *msg++; + /* second byte must be 0x01 */ + ret |= *msg++ ^ 0x01; + /* next ff_len bytes must be 0xff */ + ff_len = pad_len - algo->der_len - 3; + ret |= *msg ^ 0xff; + ret |= memcmp(msg, msg+1, ff_len-1); + msg += ff_len; + /* next byte must be 0x00 */ + ret |= *msg++; + /* next der_len bytes must match der_prefix */ + ret |= memcmp(msg, algo->der_prefix, algo->der_len); + + return ret; +} + +int padding_pkcs_15_verify(struct image_sign_info *info, + uint8_t *msg, int msg_len, + const uint8_t *hash, int hash_len) +{ + struct checksum_algo *checksum = info->checksum; + int ret, pad_len = msg_len - checksum->checksum_len; + + /* Check pkcs1.5 padding bytes. */ + ret = rsa_verify_padding(msg, pad_len, checksum); + if (ret) { + debug("In RSAVerify(): Padding check failed!\n"); + return -EINVAL; + } + + /* Check hash. */ + if (memcmp((uint8_t *)msg + pad_len, hash, msg_len - pad_len)) { + debug("In RSAVerify(): Hash check failed!\n"); + return -EACCES; + } + + return 0; +} + +#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT +static void u32_i2osp(uint32_t val, uint8_t *buf) +{ + buf[0] = (uint8_t)((val >> 24) & 0xff); + buf[1] = (uint8_t)((val >> 16) & 0xff); + buf[2] = (uint8_t)((val >> 8) & 0xff); + buf[3] = (uint8_t)((val >> 0) & 0xff); +} + +/** + * mask_generation_function1() - generate an octet string + * + * Generate an octet string used to check rsa signature. + * It use an input octet string and a hash function. + * + * @checksum: A Hash function + * @seed: Specifies an input variable octet string + * @seed_len: Size of the input octet string + * @output: Specifies the output octet string + * @output_len: Size of the output octet string + * @return 0 if the octet string was correctly generated, others on error + */ +static int mask_generation_function1(struct checksum_algo *checksum, + uint8_t *seed, int seed_len, + uint8_t *output, int output_len) +{ + struct image_region region[2]; + int ret = 0, i, i_output = 0, region_count = 2; + uint32_t counter = 0; + uint8_t buf_counter[4], *tmp; + int hash_len = checksum->checksum_len; + + memset(output, 0, output_len); + + region[0].data = seed; + region[0].size = seed_len; + region[1].data = &buf_counter[0]; + region[1].size = 4; + + tmp = malloc(hash_len); + if (!tmp) { + debug("%s: can't allocate array tmp\n", __func__); + ret = -ENOMEM; + goto out; + } + + while (i_output < output_len) { + u32_i2osp(counter, &buf_counter[0]); + + ret = checksum->calculate(checksum->name, + region, region_count, + tmp); + if (ret < 0) { + debug("%s: Error in checksum calculation\n", __func__); + goto out; + } + + i = 0; + while ((i_output < output_len) && (i < hash_len)) { + output[i_output] = tmp[i]; + i_output++; + i++; + } + + counter++; + } + +out: + free(tmp); + + return ret; +} + +static int 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) +{ + struct image_region region[3]; + int ret, region_count = 3; + + region[0].data = pad; + region[0].size = pad_len; + region[1].data = hash; + region[1].size = hash_len; + region[2].data = salt; + region[2].size = salt_len; + + ret = checksum->calculate(checksum->name, region, region_count, hprime); + if (ret < 0) { + debug("%s: Error in checksum calculation\n", __func__); + goto out; + } + +out: + return ret; +} + +/* + * padding_pss_verify() - verify the pss padding of a signature + * + * Only works with a rsa_pss_saltlen:-2 (default value) right now + * saltlen:-1 "set the salt length to the digest length" is currently + * not supported. + * + * @info: Specifies key and FIT information + * @msg: byte array of message, len equal to msg_len + * @msg_len: Message length + * @hash: Pointer to the expected hash + * @hash_len: Length of the hash + */ +int padding_pss_verify(struct image_sign_info *info, + uint8_t *msg, int msg_len, + const uint8_t *hash, int hash_len) +{ + uint8_t *masked_db = NULL; + int masked_db_len = msg_len - hash_len - 1; + uint8_t *h = NULL, *hprime = NULL; + int h_len = hash_len; + uint8_t *db_mask = NULL; + int db_mask_len = masked_db_len; + uint8_t *db = NULL, *salt = NULL; + int db_len = masked_db_len, salt_len = msg_len - hash_len - 2; + uint8_t pad_zero[8] = { 0 }; + int ret, i, leftmost_bits = 1; + uint8_t leftmost_mask; + struct checksum_algo *checksum = info->checksum; + + /* first, allocate everything */ + masked_db = malloc(masked_db_len); + h = malloc(h_len); + db_mask = malloc(db_mask_len); + db = malloc(db_len); + salt = malloc(salt_len); + hprime = malloc(hash_len); + if (!masked_db || !h || !db_mask || !db || !salt || !hprime) { + printf("%s: can't allocate some buffer\n", __func__); + ret = -ENOMEM; + goto out; + } + + /* step 4: check if the last byte is 0xbc */ + if (msg[msg_len - 1] != 0xbc) { + printf("%s: invalid pss padding (0xbc is missing)\n", __func__); + ret = -EINVAL; + goto out; + } + + /* step 5 */ + memcpy(masked_db, msg, masked_db_len); + memcpy(h, msg + masked_db_len, h_len); + + /* step 6 */ + leftmost_mask = (0xff >> (8 - leftmost_bits)) << (8 - leftmost_bits); + if (masked_db[0] & leftmost_mask) { + printf("%s: invalid pss padding ", __func__); + printf("(leftmost bit of maskedDB not zero)\n"); + ret = -EINVAL; + goto out; + } + + /* step 7 */ + mask_generation_function1(checksum, h, h_len, db_mask, db_mask_len); + + /* step 8 */ + for (i = 0; i < db_len; i++) + db[i] = masked_db[i] ^ db_mask[i]; + + /* step 9 */ + db[0] &= 0xff >> leftmost_bits; + + /* step 10 */ + if (db[0] != 0x01) { + printf("%s: invalid pss padding ", __func__); + printf("(leftmost byte of db isn't 0x01)\n"); + ret = EINVAL; + goto out; + } + + /* step 11 */ + memcpy(salt, &db[1], salt_len); + + /* step 12 & 13 */ + compute_hash_prime(checksum, pad_zero, 8, + (uint8_t *)hash, hash_len, + salt, salt_len, hprime); + + /* step 14 */ + ret = memcmp(h, hprime, hash_len); + +out: + free(hprime); + free(salt); + free(db); + free(db_mask); + free(h); + free(masked_db); + + return ret; +} +#endif + +#if CONFIG_IS_ENABLED(FIT_SIGNATURE) || CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) +/** + * rsa_verify_key() - Verify a signature against some data using RSA Key + * + * Verify a RSA PKCS1.5 signature against an expected hash using + * the RSA Key properties in prop structure. + * + * @info: Specifies key and FIT information + * @prop: Specifies key + * @sig: Signature + * @sig_len: Number of bytes in signature + * @hash: Pointer to the expected hash + * @key_len: Number of bytes in rsa key + * @return 0 if verified, -ve on error + */ +static int 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) +{ + int ret; +#if !defined(USE_HOSTCC) + struct udevice *mod_exp_dev; +#endif + struct checksum_algo *checksum = info->checksum; + struct padding_algo *padding = info->padding; + int hash_len; + + if (!prop || !sig || !hash || !checksum) + return -EIO; + + if (sig_len != (prop->num_bits / 8)) { + debug("Signature is of incorrect length %d\n", sig_len); + return -EINVAL; + } + + debug("Checksum algorithm: %s", checksum->name); + + /* Sanity check for stack size */ + if (sig_len > RSA_MAX_SIG_BITS / 8) { + debug("Signature length %u exceeds maximum %d\n", sig_len, + RSA_MAX_SIG_BITS / 8); + return -EINVAL; + } + + uint8_t buf[sig_len]; + hash_len = checksum->checksum_len; + +#if !defined(USE_HOSTCC) + ret = uclass_get_device(UCLASS_MOD_EXP, 0, &mod_exp_dev); + if (ret) { + printf("RSA: Can't find Modular Exp implementation\n"); + return -EINVAL; + } + + ret = rsa_mod_exp(mod_exp_dev, sig, sig_len, prop, buf); +#else + ret = rsa_mod_exp_sw(sig, sig_len, prop, buf); +#endif + if (ret) { + debug("Error in Modular exponentation\n"); + return ret; + } + + ret = padding->verify(info, buf, key_len, hash, hash_len); + if (ret) { + debug("In RSAVerify(): padding check failed!\n"); + return ret; + } + + return 0; +} +#endif + +#if CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) +/** + * rsa_verify_with_pkey() - Verify a signature against some data using + * only modulus and exponent as RSA key properties. + * @info: Specifies key information + * @hash: Pointer to the expected hash + * @sig: Signature + * @sig_len: Number of bytes in signature + * + * Parse a RSA public key blob in DER format pointed to in @info and fill + * a key_prop structure with properties of the key. Then verify a RSA PKCS1.5 + * signature against an expected hash using the calculated properties. + * + * Return 0 if verified, -ve on error + */ +int rsa_verify_with_pkey(struct image_sign_info *info, + const void *hash, uint8_t *sig, uint sig_len) +{ + struct key_prop *prop; + int ret; + + /* Public key is self-described to fill key_prop */ + ret = rsa_gen_key_prop(info->key, info->keylen, &prop); + if (ret) { + debug("Generating necessary parameter for decoding failed\n"); + return ret; + } + + ret = rsa_verify_key(info, prop, sig, sig_len, hash, + info->crypto->key_len); + + rsa_free_key_prop(prop); + + return ret; +} +#else +int rsa_verify_with_pkey(struct image_sign_info *info, + const void *hash, uint8_t *sig, uint sig_len) +{ + return -EACCES; +} +#endif + +#if CONFIG_IS_ENABLED(FIT_SIGNATURE) +/** + * rsa_verify_with_keynode() - Verify a signature against some data using + * information in node with prperties of RSA Key like modulus, exponent etc. + * + * Parse sign-node and fill a key_prop structure with properties of the + * key. Verify a RSA PKCS1.5 signature against an expected hash using + * the properties parsed + * + * @info: Specifies key and FIT information + * @hash: Pointer to the expected hash + * @sig: Signature + * @sig_len: Number of bytes in signature + * @node: Node having the RSA Key properties + * @return 0 if verified, -ve on error + */ +static int rsa_verify_with_keynode(struct image_sign_info *info, + const void *hash, uint8_t *sig, + uint sig_len, int node) +{ + const void *blob = info->fdt_blob; + struct key_prop prop; + int length; + int ret = 0; + const char *algo; + + if (node < 0) { + debug("%s: Skipping invalid node", __func__); + return -EBADF; + } + + algo = fdt_getprop(blob, node, "algo", NULL); + if (strcmp(info->name, algo)) { + debug("%s: Wrong algo: have %s, expected %s", __func__, + info->name, algo); + return -EFAULT; + } + + prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0); + + prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0); + + prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length); + if (!prop.public_exponent || length < sizeof(uint64_t)) + prop.public_exponent = NULL; + + prop.exp_len = sizeof(uint64_t); + + prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL); + + prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL); + + if (!prop.num_bits || !prop.modulus || !prop.rr) { + debug("%s: Missing RSA key info", __func__); + return -EFAULT; + } + + ret = rsa_verify_key(info, &prop, sig, sig_len, hash, + info->crypto->key_len); + + return ret; +} +#else +static int rsa_verify_with_keynode(struct image_sign_info *info, + const void *hash, uint8_t *sig, + uint sig_len, int node) +{ + return -EACCES; +} +#endif + +int rsa_verify_hash(struct image_sign_info *info, + const uint8_t *hash, uint8_t *sig, uint sig_len) +{ + int ret = -EACCES; + + if (CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) && !info->fdt_blob) { + /* don't rely on fdt properties */ + ret = rsa_verify_with_pkey(info, hash, sig, sig_len); + + return ret; + } + + if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) { + const void *blob = info->fdt_blob; + int ndepth, noffset; + int sig_node, node; + char name[100]; + + sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME); + if (sig_node < 0) { + debug("%s: No signature node found\n", __func__); + return -ENOENT; + } + + /* See if we must use a particular key */ + if (info->required_keynode != -1) { + ret = rsa_verify_with_keynode(info, hash, sig, sig_len, + info->required_keynode); + return ret; + } + + /* Look for a key that matches our hint */ + snprintf(name, sizeof(name), "key-%s", info->keyname); + node = fdt_subnode_offset(blob, sig_node, name); + ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node); + if (!ret) + return ret; + + /* No luck, so try each of the keys in turn */ + for (ndepth = 0, noffset = fdt_next_node(blob, sig_node, + &ndepth); + (noffset >= 0) && (ndepth > 0); + noffset = fdt_next_node(blob, noffset, &ndepth)) { + if (ndepth == 1 && noffset != node) { + ret = rsa_verify_with_keynode(info, hash, + sig, sig_len, + noffset); + if (!ret) + break; + } + } + } + + return ret; +} + +int rsa_verify(struct image_sign_info *info, + const struct image_region region[], int region_count, + uint8_t *sig, uint sig_len) +{ + /* Reserve memory for maximum checksum-length */ + uint8_t hash[info->crypto->key_len]; + int ret; + + /* + * Verify that the checksum-length does not exceed the + * rsa-signature-length + */ + if (info->checksum->checksum_len > + info->crypto->key_len) { + debug("%s: invlaid checksum-algorithm %s for %s\n", + __func__, info->checksum->name, info->crypto->name); + return -EINVAL; + } + + /* Calculate checksum with checksum-algorithm */ + ret = info->checksum->calculate(info->checksum->name, + region, region_count, hash); + if (ret < 0) { + debug("%s: Error in checksum calculation\n", __func__); + return -EINVAL; + } + + return rsa_verify_hash(info, hash, sig, sig_len); +} |