--- /dev/null
+/*
+ * 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);
+ }
+
+ offset = end_tbs; /* skip the v3 data */
+ if (asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) ||
+ asn1_signature(cert, &offset, x509_ctx))
+ goto end_cert;
+#endif
+
+ if (len)
+ {
+ *len = cert_size;
+ }
+
+ ret = X509_OK;
+end_cert:
+
+#ifdef CONFIG_SSL_FULL_MODE
+ if (ret)
+ {
+ printf("Error: Invalid X509 ASN.1 file\n");
+ }
+#endif
+
+ 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);
+ }
+#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 *)alloca(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);
+ 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();
+}
+
+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";
+ }
+}
+#endif /* CONFIG_SSL_FULL_MODE */
+
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