flm01/openwrt/package/luci/libs/nixio/axTLS/ssl/x509.c

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/*
* 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 */