diff options
Diffstat (limited to 'ccast/axTLS/x509.c')
| -rw-r--r-- | ccast/axTLS/x509.c | 561 |
1 files changed, 561 insertions, 0 deletions
diff --git a/ccast/axTLS/x509.c b/ccast/axTLS/x509.c new file mode 100644 index 0000000..c2ca49f --- /dev/null +++ b/ccast/axTLS/x509.c @@ -0,0 +1,561 @@ +/* + * Copyright (c) 2007, Cameron Rich + * + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * * Neither the name of the axTLS project nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/** + * @file x509.c + * + * Certificate processing. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include "os_port.h" +#include "crypto_misc.h" + +#ifdef CONFIG_SSL_CERT_VERIFICATION +/** + * Retrieve the signature from a certificate. + */ +static const uint8_t *get_signature(const uint8_t *asn1_sig, int *len) +{ + int offset = 0; + const uint8_t *ptr = NULL; + + if (asn1_next_obj(asn1_sig, &offset, ASN1_SEQUENCE) < 0 || + asn1_skip_obj(asn1_sig, &offset, ASN1_SEQUENCE)) + goto end_get_sig; + + if (asn1_sig[offset++] != ASN1_OCTET_STRING) + goto end_get_sig; + *len = get_asn1_length(asn1_sig, &offset); + ptr = &asn1_sig[offset]; /* all ok */ + +end_get_sig: + return ptr; +} + +#endif + +/** + * Construct a new x509 object. + * @return 0 if ok. < 0 if there was a problem. + */ +int x509_new(const uint8_t *cert, int *len, X509_CTX **ctx) +{ + int begin_tbs, end_tbs; + int ret = X509_NOT_OK, offset = 0, cert_size = 0; + X509_CTX *x509_ctx; + BI_CTX *bi_ctx; + + *ctx = (X509_CTX *)calloc(1, sizeof(X509_CTX)); + x509_ctx = *ctx; + + /* get the certificate size */ + asn1_skip_obj(cert, &cert_size, ASN1_SEQUENCE); + + if (asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0) + goto end_cert; + + begin_tbs = offset; /* start of the tbs */ + end_tbs = begin_tbs; /* work out the end of the tbs */ + asn1_skip_obj(cert, &end_tbs, ASN1_SEQUENCE); + + if (asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0) + goto end_cert; + + if (cert[offset] == ASN1_EXPLICIT_TAG) /* optional version */ + { + if (asn1_version(cert, &offset, x509_ctx)) + goto end_cert; + } + + if (asn1_skip_obj(cert, &offset, ASN1_INTEGER) || /* serial number */ + asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0) + goto end_cert; + + /* make sure the signature is ok */ + if (asn1_signature_type(cert, &offset, x509_ctx)) + { + ret = X509_VFY_ERROR_UNSUPPORTED_DIGEST; + goto end_cert; + } + + if (asn1_name(cert, &offset, x509_ctx->ca_cert_dn) || + asn1_validity(cert, &offset, x509_ctx) || + asn1_name(cert, &offset, x509_ctx->cert_dn) || + asn1_public_key(cert, &offset, x509_ctx)) + { + goto end_cert; + } + + bi_ctx = x509_ctx->rsa_ctx->bi_ctx; + +#ifdef CONFIG_SSL_CERT_VERIFICATION /* only care if doing verification */ + /* use the appropriate signature algorithm (SHA1/MD5/MD2) */ + if (x509_ctx->sig_type == SIG_TYPE_MD5) + { + MD5_CTX md5_ctx; + uint8_t md5_dgst[MD5_SIZE]; + MD5_Init(&md5_ctx); + MD5_Update(&md5_ctx, &cert[begin_tbs], end_tbs-begin_tbs); + MD5_Final(md5_dgst, &md5_ctx); + x509_ctx->digest = bi_import(bi_ctx, md5_dgst, MD5_SIZE); + } + else if (x509_ctx->sig_type == SIG_TYPE_SHA1) + { + SHA1_CTX sha_ctx; + uint8_t sha_dgst[SHA1_SIZE]; + SHA1_Init(&sha_ctx); + SHA1_Update(&sha_ctx, &cert[begin_tbs], end_tbs-begin_tbs); + SHA1_Final(sha_dgst, &sha_ctx); + x509_ctx->digest = bi_import(bi_ctx, sha_dgst, SHA1_SIZE); + } + else if (x509_ctx->sig_type == SIG_TYPE_MD2) + { + MD2_CTX md2_ctx; + uint8_t md2_dgst[MD2_SIZE]; + MD2_Init(&md2_ctx); + MD2_Update(&md2_ctx, &cert[begin_tbs], end_tbs-begin_tbs); + MD2_Final(md2_dgst, &md2_ctx); + x509_ctx->digest = bi_import(bi_ctx, md2_dgst, MD2_SIZE); + } + + if (cert[offset] == ASN1_V3_DATA) + { + int suboffset; + + ++offset; + get_asn1_length(cert, &offset); + + if ((suboffset = asn1_find_subjectaltname(cert, offset)) > 0) + { + if (asn1_next_obj(cert, &suboffset, ASN1_OCTET_STRING) > 0) + { + int altlen; + + if ((altlen = asn1_next_obj(cert, + &suboffset, ASN1_SEQUENCE)) > 0) + { + int endalt = suboffset + altlen; + int totalnames = 0; + + while (suboffset < endalt) + { + int type = cert[suboffset++]; + int dnslen = get_asn1_length(cert, &suboffset); + + if (type == ASN1_CONTEXT_DNSNAME) + { + x509_ctx->subject_alt_dnsnames = (char**) + realloc(x509_ctx->subject_alt_dnsnames, + (totalnames + 2) * sizeof(char*)); + x509_ctx->subject_alt_dnsnames[totalnames] = + (char*)malloc(dnslen + 1); + x509_ctx->subject_alt_dnsnames[totalnames+1] = NULL; + memcpy(x509_ctx->subject_alt_dnsnames[totalnames], + cert + suboffset, dnslen); + x509_ctx->subject_alt_dnsnames[ + totalnames][dnslen] = 0; + ++totalnames; + } + + suboffset += dnslen; + } + } + } + } + } + + offset = end_tbs; /* skip the rest of v3 data */ + if (asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) || + asn1_signature(cert, &offset, x509_ctx)) + goto end_cert; +#endif + ret = X509_OK; +end_cert: + if (len) + { + *len = cert_size; + } + + if (ret) + { +#ifdef CONFIG_SSL_FULL_MODE + printf("Error: Invalid X509 ASN.1 file (%s)\n", + x509_display_error(ret)); +#endif + x509_free(x509_ctx); + *ctx = NULL; + } + + return ret; +} + +/** + * Free an X.509 object's resources. + */ +void x509_free(X509_CTX *x509_ctx) +{ + X509_CTX *next; + int i; + + if (x509_ctx == NULL) /* if already null, then don't bother */ + return; + + for (i = 0; i < X509_NUM_DN_TYPES; i++) + { + free(x509_ctx->ca_cert_dn[i]); + free(x509_ctx->cert_dn[i]); + } + + free(x509_ctx->signature); + +#ifdef CONFIG_SSL_CERT_VERIFICATION + if (x509_ctx->digest) + { + bi_free(x509_ctx->rsa_ctx->bi_ctx, x509_ctx->digest); + } + + if (x509_ctx->subject_alt_dnsnames) + { + for (i = 0; x509_ctx->subject_alt_dnsnames[i]; ++i) + free(x509_ctx->subject_alt_dnsnames[i]); + + free(x509_ctx->subject_alt_dnsnames); + } +#endif + + RSA_free(x509_ctx->rsa_ctx); + next = x509_ctx->next; + free(x509_ctx); + x509_free(next); /* clear the chain */ +} + +#ifdef CONFIG_SSL_CERT_VERIFICATION +/** + * Take a signature and decrypt it. + */ +static bigint *sig_verify(BI_CTX *ctx, const uint8_t *sig, int sig_len, + bigint *modulus, bigint *pub_exp) +{ + int i, size; + bigint *decrypted_bi, *dat_bi; + bigint *bir = NULL; + uint8_t *block = (uint8_t *)malloc(sig_len); + + /* decrypt */ + dat_bi = bi_import(ctx, sig, sig_len); + ctx->mod_offset = BIGINT_M_OFFSET; + + /* convert to a normal block */ + decrypted_bi = bi_mod_power2(ctx, dat_bi, modulus, pub_exp); + + bi_export(ctx, decrypted_bi, block, sig_len); + ctx->mod_offset = BIGINT_M_OFFSET; + + i = 10; /* start at the first possible non-padded byte */ + while (block[i++] && i < sig_len); + size = sig_len - i; + + /* get only the bit we want */ + if (size > 0) + { + int len; + const uint8_t *sig_ptr = get_signature(&block[i], &len); + + if (sig_ptr) + { + bir = bi_import(ctx, sig_ptr, len); + } + } + + /* save a few bytes of memory */ + bi_clear_cache(ctx); + free(block); + return bir; +} + +/** + * Do some basic checks on the certificate chain. + * + * Certificate verification consists of a number of checks: + * - The date of the certificate is after the start date. + * - The date of the certificate is before the finish date. + * - A root certificate exists in the certificate store. + * - That the certificate(s) are not self-signed. + * - The certificate chain is valid. + * - The signature of the certificate is valid. + */ +int x509_verify(const CA_CERT_CTX *ca_cert_ctx, const X509_CTX *cert) +{ + int ret = X509_OK, i = 0; + bigint *cert_sig; + X509_CTX *next_cert = NULL; + BI_CTX *ctx = NULL; + bigint *mod = NULL, *expn = NULL; + int match_ca_cert = 0; + struct timeval tv; + uint8_t is_self_signed = 0; + + if (cert == NULL) + { + ret = X509_VFY_ERROR_NO_TRUSTED_CERT; + goto end_verify; + } + + /* a self-signed certificate that is not in the CA store - use this + to check the signature */ + if (asn1_compare_dn(cert->ca_cert_dn, cert->cert_dn) == 0) + { + is_self_signed = 1; + ctx = cert->rsa_ctx->bi_ctx; + mod = cert->rsa_ctx->m; + expn = cert->rsa_ctx->e; + } + + gettimeofday(&tv, NULL); + + /* check the not before date */ + if (tv.tv_sec < cert->not_before) + { + ret = X509_VFY_ERROR_NOT_YET_VALID; + goto end_verify; + } + + /* check the not after date */ + if (tv.tv_sec > cert->not_after) + { + ret = X509_VFY_ERROR_EXPIRED; + goto end_verify; + } + + next_cert = cert->next; + + /* last cert in the chain - look for a trusted cert */ + if (next_cert == NULL) + { + if (ca_cert_ctx != NULL) + { + /* go thu the CA store */ + while (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i]) + { + if (asn1_compare_dn(cert->ca_cert_dn, + ca_cert_ctx->cert[i]->cert_dn) == 0) + { + /* use this CA certificate for signature verification */ + match_ca_cert = 1; + ctx = ca_cert_ctx->cert[i]->rsa_ctx->bi_ctx; + mod = ca_cert_ctx->cert[i]->rsa_ctx->m; + expn = ca_cert_ctx->cert[i]->rsa_ctx->e; + break; + } + + i++; + } + } + + /* couldn't find a trusted cert (& let self-signed errors + be returned) */ + if (!match_ca_cert && !is_self_signed) + { + ret = X509_VFY_ERROR_NO_TRUSTED_CERT; + goto end_verify; + } + } + else if (asn1_compare_dn(cert->ca_cert_dn, next_cert->cert_dn) != 0) + { + /* check the chain */ + ret = X509_VFY_ERROR_INVALID_CHAIN; + goto end_verify; + } + else /* use the next certificate in the chain for signature verify */ + { + ctx = next_cert->rsa_ctx->bi_ctx; + mod = next_cert->rsa_ctx->m; + expn = next_cert->rsa_ctx->e; + } + + /* cert is self signed */ + if (!match_ca_cert && is_self_signed) + { + ret = X509_VFY_ERROR_SELF_SIGNED; + goto end_verify; + } + + /* check the signature */ + cert_sig = sig_verify(ctx, cert->signature, cert->sig_len, + bi_clone(ctx, mod), bi_clone(ctx, expn)); + + if (cert_sig && cert->digest) + { + if (bi_compare(cert_sig, cert->digest) != 0) + ret = X509_VFY_ERROR_BAD_SIGNATURE; + + + bi_free(ctx, cert_sig); + } + else + { + ret = X509_VFY_ERROR_BAD_SIGNATURE; + } + + if (ret) + goto end_verify; + + /* go down the certificate chain using recursion. */ + if (next_cert != NULL) + { + ret = x509_verify(ca_cert_ctx, next_cert); + } + +end_verify: + return ret; +} +#endif + +#if defined (CONFIG_SSL_FULL_MODE) +/** + * Used for diagnostics. + */ +static const char *not_part_of_cert = "<Not Part Of Certificate>"; +void x509_print(const X509_CTX *cert, CA_CERT_CTX *ca_cert_ctx) +{ + if (cert == NULL) + return; + + printf("=== CERTIFICATE ISSUED TO ===\n"); + printf("Common Name (CN):\t\t"); + printf("%s\n", cert->cert_dn[X509_COMMON_NAME] ? + cert->cert_dn[X509_COMMON_NAME] : not_part_of_cert); + + printf("Organization (O):\t\t"); + printf("%s\n", cert->cert_dn[X509_ORGANIZATION] ? + cert->cert_dn[X509_ORGANIZATION] : not_part_of_cert); + + printf("Organizational Unit (OU):\t"); + printf("%s\n", cert->cert_dn[X509_ORGANIZATIONAL_UNIT] ? + cert->cert_dn[X509_ORGANIZATIONAL_UNIT] : not_part_of_cert); + + printf("=== CERTIFICATE ISSUED BY ===\n"); + printf("Common Name (CN):\t\t"); + printf("%s\n", cert->ca_cert_dn[X509_COMMON_NAME] ? + cert->ca_cert_dn[X509_COMMON_NAME] : not_part_of_cert); + + printf("Organization (O):\t\t"); + printf("%s\n", cert->ca_cert_dn[X509_ORGANIZATION] ? + cert->ca_cert_dn[X509_ORGANIZATION] : not_part_of_cert); + + printf("Organizational Unit (OU):\t"); + printf("%s\n", cert->ca_cert_dn[X509_ORGANIZATIONAL_UNIT] ? + cert->ca_cert_dn[X509_ORGANIZATIONAL_UNIT] : not_part_of_cert); + + printf("Not Before:\t\t\t%s", ctime(&cert->not_before)); + printf("Not After:\t\t\t%s", ctime(&cert->not_after)); + printf("RSA bitsize:\t\t\t%d\n", cert->rsa_ctx->num_octets*8); + printf("Sig Type:\t\t\t"); + switch (cert->sig_type) + { + case SIG_TYPE_MD5: + printf("MD5\n"); + break; + case SIG_TYPE_SHA1: + printf("SHA1\n"); + break; + case SIG_TYPE_MD2: + printf("MD2\n"); + break; + default: + printf("Unrecognized: %d\n", cert->sig_type); + break; + } + + if (ca_cert_ctx) + { + printf("Verify:\t\t\t\t%s\n", + x509_display_error(x509_verify(ca_cert_ctx, cert))); + } + +#if 0 + print_blob("Signature", cert->signature, cert->sig_len); + bi_print("Modulus", cert->rsa_ctx->m); + bi_print("Pub Exp", cert->rsa_ctx->e); +#endif + + if (ca_cert_ctx) + { + x509_print(cert->next, ca_cert_ctx); + } + + TTY_FLUSH(); +} + +#endif /* CONFIG_SSL_FULL_MODE */ + +const char * x509_display_error(int error) +{ + switch (error) + { + case X509_OK: + return "Certificate verify successful"; + + case X509_NOT_OK: + return "X509 not ok"; + + case X509_VFY_ERROR_NO_TRUSTED_CERT: + return "No trusted cert is available"; + + case X509_VFY_ERROR_BAD_SIGNATURE: + return "Bad signature"; + + case X509_VFY_ERROR_NOT_YET_VALID: + return "Cert is not yet valid"; + + case X509_VFY_ERROR_EXPIRED: + return "Cert has expired"; + + case X509_VFY_ERROR_SELF_SIGNED: + return "Cert is self-signed"; + + case X509_VFY_ERROR_INVALID_CHAIN: + return "Chain is invalid (check order of certs)"; + + case X509_VFY_ERROR_UNSUPPORTED_DIGEST: + return "Unsupported digest"; + + case X509_INVALID_PRIV_KEY: + return "Invalid private key"; + + default: + return "Unknown"; + } +} + |