diff options
Diffstat (limited to 'lib/rsa/rsa-sign.c')
| -rw-r--r-- | lib/rsa/rsa-sign.c | 460 |
1 files changed, 460 insertions, 0 deletions
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c new file mode 100644 index 000000000..a75ae245e --- /dev/null +++ b/lib/rsa/rsa-sign.c @@ -0,0 +1,460 @@ +/* + * Copyright (c) 2013, Google Inc. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include "mkimage.h" +#include <stdio.h> +#include <string.h> +#include <error.h> +#include <image.h> +#include <time.h> +#include <openssl/rsa.h> +#include <openssl/pem.h> +#include <openssl/err.h> +#include <openssl/ssl.h> +#include <openssl/evp.h> + +#if OPENSSL_VERSION_NUMBER >= 0x10000000L +#define HAVE_ERR_REMOVE_THREAD_STATE +#endif + +static int rsa_err(const char *msg) +{ + unsigned long sslErr = ERR_get_error(); + + fprintf(stderr, "%s", msg); + fprintf(stderr, ": %s\n", + ERR_error_string(sslErr, 0)); + + return -1; +} + +/** + * rsa_get_pub_key() - read a public key from a .crt file + * + * @keydir: Directory containins the key + * @name Name of key file (will have a .crt extension) + * @rsap Returns RSA object, or NULL on failure + * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) + */ +static int rsa_get_pub_key(const char *keydir, const char *name, RSA **rsap) +{ + char path[1024]; + EVP_PKEY *key; + X509 *cert; + RSA *rsa; + FILE *f; + int ret; + + *rsap = NULL; + snprintf(path, sizeof(path), "%s/%s.crt", keydir, name); + f = fopen(path, "r"); + if (!f) { + fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n", + path, strerror(errno)); + return -EACCES; + } + + /* Read the certificate */ + cert = NULL; + if (!PEM_read_X509(f, &cert, NULL, NULL)) { + rsa_err("Couldn't read certificate"); + ret = -EINVAL; + goto err_cert; + } + + /* Get the public key from the certificate. */ + key = X509_get_pubkey(cert); + if (!key) { + rsa_err("Couldn't read public key\n"); + ret = -EINVAL; + goto err_pubkey; + } + + /* Convert to a RSA_style key. */ + rsa = EVP_PKEY_get1_RSA(key); + if (!rsa) { + rsa_err("Couldn't convert to a RSA style key"); + goto err_rsa; + } + fclose(f); + EVP_PKEY_free(key); + X509_free(cert); + *rsap = rsa; + + return 0; + +err_rsa: + EVP_PKEY_free(key); +err_pubkey: + X509_free(cert); +err_cert: + fclose(f); + return ret; +} + +/** + * rsa_get_priv_key() - read a private key from a .key file + * + * @keydir: Directory containins the key + * @name Name of key file (will have a .key extension) + * @rsap Returns RSA object, or NULL on failure + * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) + */ +static int rsa_get_priv_key(const char *keydir, const char *name, RSA **rsap) +{ + char path[1024]; + RSA *rsa; + FILE *f; + + *rsap = NULL; + snprintf(path, sizeof(path), "%s/%s.key", keydir, name); + f = fopen(path, "r"); + if (!f) { + fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n", + path, strerror(errno)); + return -ENOENT; + } + + rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path); + if (!rsa) { + rsa_err("Failure reading private key"); + fclose(f); + return -EPROTO; + } + fclose(f); + *rsap = rsa; + + return 0; +} + +static int rsa_init(void) +{ + int ret; + + ret = SSL_library_init(); + if (!ret) { + fprintf(stderr, "Failure to init SSL library\n"); + return -1; + } + SSL_load_error_strings(); + + OpenSSL_add_all_algorithms(); + OpenSSL_add_all_digests(); + OpenSSL_add_all_ciphers(); + + return 0; +} + +static void rsa_remove(void) +{ + CRYPTO_cleanup_all_ex_data(); + ERR_free_strings(); +#ifdef HAVE_ERR_REMOVE_THREAD_STATE + ERR_remove_thread_state(NULL); +#else + ERR_remove_state(0); +#endif + EVP_cleanup(); +} + +static int rsa_sign_with_key(RSA *rsa, const struct image_region region[], + int region_count, uint8_t **sigp, uint *sig_size) +{ + EVP_PKEY *key; + EVP_MD_CTX *context; + int size, ret = 0; + uint8_t *sig; + int i; + + key = EVP_PKEY_new(); + if (!key) + return rsa_err("EVP_PKEY object creation failed"); + + if (!EVP_PKEY_set1_RSA(key, rsa)) { + ret = rsa_err("EVP key setup failed"); + goto err_set; + } + + size = EVP_PKEY_size(key); + sig = malloc(size); + if (!sig) { + fprintf(stderr, "Out of memory for signature (%d bytes)\n", + size); + ret = -ENOMEM; + goto err_alloc; + } + + context = EVP_MD_CTX_create(); + if (!context) { + ret = rsa_err("EVP context creation failed"); + goto err_create; + } + EVP_MD_CTX_init(context); + if (!EVP_SignInit(context, EVP_sha1())) { + ret = rsa_err("Signer setup failed"); + goto err_sign; + } + + for (i = 0; i < region_count; i++) { + if (!EVP_SignUpdate(context, region[i].data, region[i].size)) { + ret = rsa_err("Signing data failed"); + goto err_sign; + } + } + + if (!EVP_SignFinal(context, sig, sig_size, key)) { + ret = rsa_err("Could not obtain signature"); + goto err_sign; + } + EVP_MD_CTX_cleanup(context); + EVP_MD_CTX_destroy(context); + EVP_PKEY_free(key); + + debug("Got signature: %d bytes, expected %d\n", *sig_size, size); + *sigp = sig; + *sig_size = size; + + return 0; + +err_sign: + EVP_MD_CTX_destroy(context); +err_create: + free(sig); +err_alloc: +err_set: + EVP_PKEY_free(key); + return ret; +} + +int rsa_sign(struct image_sign_info *info, + const struct image_region region[], int region_count, + uint8_t **sigp, uint *sig_len) +{ + RSA *rsa; + int ret; + + ret = rsa_init(); + if (ret) + return ret; + + ret = rsa_get_priv_key(info->keydir, info->keyname, &rsa); + if (ret) + goto err_priv; + ret = rsa_sign_with_key(rsa, region, region_count, sigp, sig_len); + if (ret) + goto err_sign; + + RSA_free(rsa); + rsa_remove(); + + return ret; + +err_sign: + RSA_free(rsa); +err_priv: + rsa_remove(); + return ret; +} + +/* + * rsa_get_params(): - Get the important parameters of an RSA public key + */ +int rsa_get_params(RSA *key, uint32_t *n0_invp, BIGNUM **modulusp, + BIGNUM **r_squaredp) +{ + BIGNUM *big1, *big2, *big32, *big2_32; + BIGNUM *n, *r, *r_squared, *tmp; + BN_CTX *bn_ctx = BN_CTX_new(); + int ret = 0; + + /* Initialize BIGNUMs */ + big1 = BN_new(); + big2 = BN_new(); + big32 = BN_new(); + r = BN_new(); + r_squared = BN_new(); + tmp = BN_new(); + big2_32 = BN_new(); + n = BN_new(); + if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 || + !n) { + fprintf(stderr, "Out of memory (bignum)\n"); + return -ENOMEM; + } + + if (!BN_copy(n, key->n) || !BN_set_word(big1, 1L) || + !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L)) + ret = -1; + + /* big2_32 = 2^32 */ + if (!BN_exp(big2_32, big2, big32, bn_ctx)) + ret = -1; + + /* Calculate n0_inv = -1 / n[0] mod 2^32 */ + if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) || + !BN_sub(tmp, big2_32, tmp)) + ret = -1; + *n0_invp = BN_get_word(tmp); + + /* Calculate R = 2^(# of key bits) */ + if (!BN_set_word(tmp, BN_num_bits(n)) || + !BN_exp(r, big2, tmp, bn_ctx)) + ret = -1; + + /* Calculate r_squared = R^2 mod n */ + if (!BN_copy(r_squared, r) || + !BN_mul(tmp, r_squared, r, bn_ctx) || + !BN_mod(r_squared, tmp, n, bn_ctx)) + ret = -1; + + *modulusp = n; + *r_squaredp = r_squared; + + BN_free(big1); + BN_free(big2); + BN_free(big32); + BN_free(r); + BN_free(tmp); + BN_free(big2_32); + if (ret) { + fprintf(stderr, "Bignum operations failed\n"); + return -ENOMEM; + } + + return ret; +} + +static int fdt_add_bignum(void *blob, int noffset, const char *prop_name, + BIGNUM *num, int num_bits) +{ + int nwords = num_bits / 32; + int size; + uint32_t *buf, *ptr; + BIGNUM *tmp, *big2, *big32, *big2_32; + BN_CTX *ctx; + int ret; + + tmp = BN_new(); + big2 = BN_new(); + big32 = BN_new(); + big2_32 = BN_new(); + if (!tmp || !big2 || !big32 || !big2_32) { + fprintf(stderr, "Out of memory (bignum)\n"); + return -ENOMEM; + } + ctx = BN_CTX_new(); + if (!tmp) { + fprintf(stderr, "Out of memory (bignum context)\n"); + return -ENOMEM; + } + BN_set_word(big2, 2L); + BN_set_word(big32, 32L); + BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */ + + size = nwords * sizeof(uint32_t); + buf = malloc(size); + if (!buf) { + fprintf(stderr, "Out of memory (%d bytes)\n", size); + return -ENOMEM; + } + + /* Write out modulus as big endian array of integers */ + for (ptr = buf + nwords - 1; ptr >= buf; ptr--) { + BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */ + *ptr = cpu_to_fdt32(BN_get_word(tmp)); + BN_rshift(num, num, 32); /* N = N/B */ + } + + ret = fdt_setprop(blob, noffset, prop_name, buf, size); + if (ret) { + fprintf(stderr, "Failed to write public key to FIT\n"); + return -ENOSPC; + } + free(buf); + BN_free(tmp); + BN_free(big2); + BN_free(big32); + BN_free(big2_32); + + return ret; +} + +int rsa_add_verify_data(struct image_sign_info *info, void *keydest) +{ + BIGNUM *modulus, *r_squared; + uint32_t n0_inv; + int parent, node; + char name[100]; + int ret; + int bits; + RSA *rsa; + + debug("%s: Getting verification data\n", __func__); + ret = rsa_get_pub_key(info->keydir, info->keyname, &rsa); + if (ret) + return ret; + ret = rsa_get_params(rsa, &n0_inv, &modulus, &r_squared); + if (ret) + return ret; + bits = BN_num_bits(modulus); + parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME); + if (parent == -FDT_ERR_NOTFOUND) { + parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME); + if (parent < 0) { + fprintf(stderr, "Couldn't create signature node: %s\n", + fdt_strerror(parent)); + return -EINVAL; + } + } + + /* Either create or overwrite the named key node */ + snprintf(name, sizeof(name), "key-%s", info->keyname); + node = fdt_subnode_offset(keydest, parent, name); + if (node == -FDT_ERR_NOTFOUND) { + node = fdt_add_subnode(keydest, parent, name); + if (node < 0) { + fprintf(stderr, "Could not create key subnode: %s\n", + fdt_strerror(node)); + return -EINVAL; + } + } else if (node < 0) { + fprintf(stderr, "Cannot select keys parent: %s\n", + fdt_strerror(node)); + return -ENOSPC; + } + + ret = fdt_setprop_string(keydest, node, "key-name-hint", + info->keyname); + ret |= fdt_setprop_u32(keydest, node, "rsa,num-bits", bits); + ret |= fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv); + ret |= fdt_add_bignum(keydest, node, "rsa,modulus", modulus, bits); + ret |= fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared, bits); + ret |= fdt_setprop_string(keydest, node, FIT_ALGO_PROP, + info->algo->name); + if (info->require_keys) { + fdt_setprop_string(keydest, node, "required", + info->require_keys); + } + BN_free(modulus); + BN_free(r_squared); + if (ret) + return -EIO; + + return 0; +} |