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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.
*/
/**
* Some primitive asn methods for extraction ASN.1 data.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "os_port.h"
#include "crypto.h"
#include "crypto_misc.h"
#define SIG_OID_PREFIX_SIZE 8
#define SIG_IIS6_OID_SIZE 5
#define SIG_SUBJECT_ALT_NAME_SIZE 3
/* Must be an RSA algorithm with either SHA1 or MD5 for verifying to work */
static const uint8_t sig_oid_prefix[SIG_OID_PREFIX_SIZE] =
{
0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01
};
static const uint8_t sig_sha1WithRSAEncrypt[SIG_IIS6_OID_SIZE] =
{
0x2b, 0x0e, 0x03, 0x02, 0x1d
};
static const uint8_t sig_subject_alt_name[SIG_SUBJECT_ALT_NAME_SIZE] =
{
0x55, 0x1d, 0x11
};
/* CN, O, OU */
static const uint8_t g_dn_types[] = { 3, 10, 11 };
int get_asn1_length(const uint8_t *buf, int *offset)
{
int len, i;
if (!(buf[*offset] & 0x80)) /* short form */
{
len = buf[(*offset)++];
}
else /* long form */
{
int length_bytes = buf[(*offset)++]&0x7f;
len = 0;
for (i = 0; i < length_bytes; i++)
{
len <<= 8;
len += buf[(*offset)++];
}
}
return len;
}
/**
* Skip the ASN1.1 object type and its length. Get ready to read the object's
* data.
*/
int asn1_next_obj(const uint8_t *buf, int *offset, int obj_type)
{
if (buf[*offset] != obj_type)
return X509_NOT_OK;
(*offset)++;
return get_asn1_length(buf, offset);
}
/**
* Skip over an ASN.1 object type completely. Get ready to read the next
* object.
*/
int asn1_skip_obj(const uint8_t *buf, int *offset, int obj_type)
{
int len;
if (buf[*offset] != obj_type)
return X509_NOT_OK;
(*offset)++;
len = get_asn1_length(buf, offset);
*offset += len;
return 0;
}
/**
* Read an integer value for ASN.1 data
* Note: This function allocates memory which must be freed by the user.
*/
int asn1_get_int(const uint8_t *buf, int *offset, uint8_t **object)
{
int len;
if ((len = asn1_next_obj(buf, offset, ASN1_INTEGER)) < 0)
goto end_int_array;
if (len > 1 && buf[*offset] == 0x00) /* ignore the negative byte */
{
len--;
(*offset)++;
}
*object = (uint8_t *)malloc(len);
memcpy(*object, &buf[*offset], len);
*offset += len;
end_int_array:
return len;
}
/**
* Get all the RSA private key specifics from an ASN.1 encoded file
*/
int asn1_get_private_key(const uint8_t *buf, int len, RSA_CTX **rsa_ctx)
{
int offset = 7;
uint8_t *modulus = NULL, *priv_exp = NULL, *pub_exp = NULL;
int mod_len, priv_len, pub_len;
#ifdef CONFIG_BIGINT_CRT
uint8_t *p = NULL, *q = NULL, *dP = NULL, *dQ = NULL, *qInv = NULL;
int p_len, q_len, dP_len, dQ_len, qInv_len;
#endif
/* not in der format */
if (buf[0] != ASN1_SEQUENCE) /* basic sanity check */
{
#ifdef CONFIG_SSL_FULL_MODE
printf("Error: This is not a valid ASN.1 file\n");
#endif
return X509_INVALID_PRIV_KEY;
}
/* Use the private key to mix up the RNG if possible. */
RNG_custom_init(buf, len);
mod_len = asn1_get_int(buf, &offset, &modulus);
pub_len = asn1_get_int(buf, &offset, &pub_exp);
priv_len = asn1_get_int(buf, &offset, &priv_exp);
if (mod_len <= 0 || pub_len <= 0 || priv_len <= 0)
return X509_INVALID_PRIV_KEY;
#ifdef CONFIG_BIGINT_CRT
p_len = asn1_get_int(buf, &offset, &p);
q_len = asn1_get_int(buf, &offset, &q);
dP_len = asn1_get_int(buf, &offset, &dP);
dQ_len = asn1_get_int(buf, &offset, &dQ);
qInv_len = asn1_get_int(buf, &offset, &qInv);
if (p_len <= 0 || q_len <= 0 || dP_len <= 0 || dQ_len <= 0 || qInv_len <= 0)
return X509_INVALID_PRIV_KEY;
RSA_priv_key_new(rsa_ctx,
modulus, mod_len, pub_exp, pub_len, priv_exp, priv_len,
p, p_len, q, p_len, dP, dP_len, dQ, dQ_len, qInv, qInv_len);
free(p);
free(q);
free(dP);
free(dQ);
free(qInv);
#else
RSA_priv_key_new(rsa_ctx,
modulus, mod_len, pub_exp, pub_len, priv_exp, priv_len);
#endif
free(modulus);
free(priv_exp);
free(pub_exp);
return X509_OK;
}
/**
* Read the modulus and public exponent of an RSA certificate.
*/
int asn1_get_public_key(const uint8_t *cert, int *offset, RSA_CTX **rsa_ctx)
{
int ret = X509_NOT_OK, mod_len, pub_len;
uint8_t *modulus = NULL, *pub_exp = NULL;
int len;
/* Hmm. Not checking that the two ints are within the squence ... */
if ((len = asn1_next_obj(cert, offset, ASN1_SEQUENCE)) < 0)
goto end_pub_key;
if ((mod_len = asn1_get_int(cert, offset, &modulus)) <= 0) {
ret = X509_INVALID_PUB_KEY;
goto end_pub_key;
}
if ((pub_len = asn1_get_int(cert, offset, &pub_exp)) <= 0) {
free(modulus);
ret = X509_INVALID_PUB_KEY;
goto end_pub_key;
}
RSA_pub_key_new(rsa_ctx, modulus, mod_len, pub_exp, pub_len);
free(modulus);
free(pub_exp);
ret = X509_OK;
end_pub_key:
return ret;
}
/**
* Get the time of a certificate. Ignore hours/minutes/seconds.
*/
static int asn1_get_utc_time(const uint8_t *buf, int *offset, time_t *t)
{
int ret = X509_NOT_OK, len, t_offset;
struct tm tm;
if (buf[(*offset)++] != ASN1_UTC_TIME)
goto end_utc_time;
len = get_asn1_length(buf, offset);
t_offset = *offset;
memset(&tm, 0, sizeof(struct tm));
tm.tm_year = (buf[t_offset] - '0')*10 + (buf[t_offset+1] - '0');
if (tm.tm_year <= 50) /* 1951-2050 thing */
{
tm.tm_year += 100;
}
tm.tm_mon = (buf[t_offset+2] - '0')*10 + (buf[t_offset+3] - '0') - 1;
tm.tm_mday = (buf[t_offset+4] - '0')*10 + (buf[t_offset+5] - '0');
*t = mktime(&tm);
*offset += len;
ret = X509_OK;
end_utc_time:
return ret;
}
/**
* Get the version type of a certificate (which we don't actually care about)
*/
int asn1_version(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
{
int ret = X509_NOT_OK;
(*offset) += 2; /* get past explicit tag */
if (asn1_skip_obj(cert, offset, ASN1_INTEGER))
goto end_version;
ret = X509_OK;
end_version:
return ret;
}
/**
* Retrieve the notbefore and notafter certificate times.
*/
int asn1_validity(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
{
return (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0 ||
asn1_get_utc_time(cert, offset, &x509_ctx->not_before) ||
asn1_get_utc_time(cert, offset, &x509_ctx->not_after));
}
/**
* Get the components of a distinguished name
*/
static int asn1_get_oid_x520(const uint8_t *buf, int *offset)
{
int dn_type = 0;
int len;
if ((len = asn1_next_obj(buf, offset, ASN1_OID)) < 0)
goto end_oid;
/* expect a sequence of 2.5.4.[x] where x is a one of distinguished name
components we are interested in. */
if (len == 3 && buf[(*offset)++] == 0x55 && buf[(*offset)++] == 0x04)
dn_type = buf[(*offset)++];
else
{
*offset += len; /* skip over it */
}
end_oid:
return dn_type;
}
/**
* Obtain an ASN.1 printable string type.
*/
static int asn1_get_printable_str(const uint8_t *buf, int *offset, char **str)
{
int len = X509_NOT_OK;
int asn1_type = buf[*offset];
/* some certs have this awful crud in them for some reason */
if (asn1_type != ASN1_PRINTABLE_STR &&
asn1_type != ASN1_PRINTABLE_STR2 &&
asn1_type != ASN1_TELETEX_STR &&
asn1_type != ASN1_IA5_STR &&
asn1_type != ASN1_UNICODE_STR)
goto end_pnt_str;
(*offset)++;
len = get_asn1_length(buf, offset);
if (asn1_type == ASN1_UNICODE_STR)
{
int i;
*str = (char *)malloc(len/2+1); /* allow for null */
for (i = 0; i < len; i += 2)
(*str)[i/2] = buf[*offset + i + 1];
(*str)[len/2] = 0; /* null terminate */
}
else
{
*str = (char *)malloc(len+1); /* allow for null */
memcpy(*str, &buf[*offset], len);
(*str)[len] = 0; /* null terminate */
}
*offset += len;
end_pnt_str:
return len;
}
/**
* Get the subject name (or the issuer) of a certificate.
*/
int asn1_name(const uint8_t *cert, int *offset, char *dn[])
{
int ret = X509_NOT_OK;
int dn_type;
char *tmp;
if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0)
goto end_name;
while (asn1_next_obj(cert, offset, ASN1_SET) >= 0)
{
int i, found = 0;
if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0 ||
(dn_type = asn1_get_oid_x520(cert, offset)) < 0)
goto end_name;
tmp = NULL;
if (asn1_get_printable_str(cert, offset, &tmp) < 0)
{
free(tmp);
goto end_name;
}
/* find the distinguished named type */
for (i = 0; i < X509_NUM_DN_TYPES; i++)
{
if (dn_type == g_dn_types[i])
{
if (dn[i] == NULL)
{
dn[i] = tmp;
found = 1;
break;
}
}
}
if (found == 0) /* not found so get rid of it */
{
free(tmp);
}
}
ret = X509_OK;
end_name:
return ret;
}
/**
* Read the modulus and public exponent of a certificate.
*/
int asn1_public_key(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
{
int ret = X509_NOT_OK, mod_len, pub_len;
uint8_t *modulus = NULL, *pub_exp = NULL;
if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0 ||
asn1_skip_obj(cert, offset, ASN1_SEQUENCE) ||
asn1_next_obj(cert, offset, ASN1_BIT_STRING) < 0)
goto end_pub_key;
(*offset)++; /* ignore the padding bit field */
if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0)
goto end_pub_key;
mod_len = asn1_get_int(cert, offset, &modulus);
pub_len = asn1_get_int(cert, offset, &pub_exp);
RSA_pub_key_new(&x509_ctx->rsa_ctx, modulus, mod_len, pub_exp, pub_len);
free(modulus);
free(pub_exp);
ret = X509_OK;
end_pub_key:
return ret;
}
#ifdef CONFIG_SSL_CERT_VERIFICATION
/**
* Read the signature of the certificate.
*/
int asn1_signature(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
{
int ret = X509_NOT_OK;
if (cert[(*offset)++] != ASN1_BIT_STRING)
goto end_sig;
x509_ctx->sig_len = get_asn1_length(cert, offset)-1;
(*offset)++; /* ignore bit string padding bits */
x509_ctx->signature = (uint8_t *)malloc(x509_ctx->sig_len);
memcpy(x509_ctx->signature, &cert[*offset], x509_ctx->sig_len);
*offset += x509_ctx->sig_len;
ret = X509_OK;
end_sig:
return ret;
}
/*
* Compare 2 distinguished name components for equality
* @return 0 if a match
*/
static int asn1_compare_dn_comp(const char *dn1, const char *dn2)
{
int ret;
if (dn1 == NULL && dn2 == NULL)
ret = 0;
else
ret = (dn1 && dn2) ? strcmp(dn1, dn2) : 1;
return ret;
}
/**
* Clean up all of the CA certificates.
*/
void remove_ca_certs(CA_CERT_CTX *ca_cert_ctx)
{
int i = 0;
if (ca_cert_ctx == NULL)
return;
while (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i])
{
x509_free(ca_cert_ctx->cert[i]);
ca_cert_ctx->cert[i++] = NULL;
}
free(ca_cert_ctx);
}
/*
* Compare 2 distinguished names for equality
* @return 0 if a match
*/
int asn1_compare_dn(char * const dn1[], char * const dn2[])
{
int i;
for (i = 0; i < X509_NUM_DN_TYPES; i++)
{
if (asn1_compare_dn_comp(dn1[i], dn2[i]))
return 1;
}
return 0; /* all good */
}
int asn1_find_oid(const uint8_t* cert, int* offset,
const uint8_t* oid, int oid_length)
{
int seqlen;
if ((seqlen = asn1_next_obj(cert, offset, ASN1_SEQUENCE))> 0)
{
int end = *offset + seqlen;
while (*offset < end)
{
int type = cert[(*offset)++];
int length = get_asn1_length(cert, offset);
int noffset = *offset + length;
if (type == ASN1_SEQUENCE)
{
type = cert[(*offset)++];
length = get_asn1_length(cert, offset);
if (type == ASN1_OID && length == oid_length &&
memcmp(cert + *offset, oid, oid_length) == 0)
{
*offset += oid_length;
return 1;
}
}
*offset = noffset;
}
}
return 0;
}
int asn1_find_subjectaltname(const uint8_t* cert, int offset)
{
if (asn1_find_oid(cert, &offset, sig_subject_alt_name,
SIG_SUBJECT_ALT_NAME_SIZE))
{
return offset;
}
return 0;
}
#endif /* CONFIG_SSL_CERT_VERIFICATION */
/**
* Read the signature type of the certificate. We only support RSA-MD5 and
* RSA-SHA1 signature types.
*/
int asn1_signature_type(const uint8_t *cert,
int *offset, X509_CTX *x509_ctx)
{
int ret = X509_NOT_OK, len;
if (cert[(*offset)++] != ASN1_OID)
goto end_check_sig;
len = get_asn1_length(cert, offset);
if (len == 5 && memcmp(sig_sha1WithRSAEncrypt, &cert[*offset],
SIG_IIS6_OID_SIZE) == 0)
{
x509_ctx->sig_type = SIG_TYPE_SHA1;
}
else
{
if (memcmp(sig_oid_prefix, &cert[*offset], SIG_OID_PREFIX_SIZE))
goto end_check_sig; /* unrecognised cert type */
x509_ctx->sig_type = cert[*offset + SIG_OID_PREFIX_SIZE];
}
*offset += len;
asn1_skip_obj(cert, offset, ASN1_NULL); /* if it's there */
ret = X509_OK;
end_check_sig:
return ret;
}
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