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mbedtls/library/x509_csr.c
Andres AG 2e3ddfac5f Prevent signed integer overflow in CSR parsing 
Modify the function mbedtls_x509_csr_parse_der() so that it checks the
parsed CSR version integer before it increments the value. This prevents
a potential signed integer overflow, as these have undefined behaviour
in the C standard.
2017-07-27 21:44:34 +01:00

424 lines
11 KiB
C
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/*
* X.509 Certificate Signing Request (CSR) parsing
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
/*
* The ITU-T X.509 standard defines a certificate format for PKI.
*
* http://www.ietf.org/rfc/rfc5280.txt (Certificates and CRLs)
* http://www.ietf.org/rfc/rfc3279.txt (Alg IDs for CRLs)
* http://www.ietf.org/rfc/rfc2986.txt (CSRs, aka PKCS#10)
*
* http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-0207.pdf
* http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_X509_CSR_PARSE_C)
#include "mbedtls/x509_csr.h"
#include "mbedtls/oid.h"
#include <string.h>
#if defined(MBEDTLS_PEM_PARSE_C)
#include "mbedtls/pem.h"
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#include <stdio.h>
#define mbedtls_free free
#define mbedtls_calloc calloc
#define mbedtls_snprintf snprintf
#endif
#if defined(MBEDTLS_FS_IO) || defined(EFIX64) || defined(EFI32)
#include <stdio.h>
#endif
/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
volatile unsigned char *p = v; while( n-- ) *p++ = 0;
}
/*
* Version ::= INTEGER { v1(0) }
*/
static int x509_csr_get_version( unsigned char **p,
const unsigned char *end,
int *ver )
{
int ret;
if( ( ret = mbedtls_asn1_get_int( p, end, ver ) ) != 0 )
{
if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
{
*ver = 0;
return( 0 );
}
return( MBEDTLS_ERR_X509_INVALID_VERSION + ret );
}
return( 0 );
}
/*
* Parse a CSR in DER format
*/
int mbedtls_x509_csr_parse_der( mbedtls_x509_csr *csr,
const unsigned char *buf, size_t buflen )
{
int ret;
size_t len;
unsigned char *p, *end;
mbedtls_x509_buf sig_params;
memset( &sig_params, 0, sizeof( mbedtls_x509_buf ) );
/*
* Check for valid input
*/
if( csr == NULL || buf == NULL || buflen == 0 )
return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
mbedtls_x509_csr_init( csr );
/*
* first copy the raw DER data
*/
p = mbedtls_calloc( 1, len = buflen );
if( p == NULL )
return( MBEDTLS_ERR_X509_ALLOC_FAILED );
memcpy( p, buf, buflen );
csr->raw.p = p;
csr->raw.len = len;
end = p + len;
/*
* CertificationRequest ::= SEQUENCE {
* certificationRequestInfo CertificationRequestInfo,
* signatureAlgorithm AlgorithmIdentifier,
* signature BIT STRING
* }
*/
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_INVALID_FORMAT );
}
if( len != (size_t) ( end - p ) )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_INVALID_FORMAT +
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
}
/*
* CertificationRequestInfo ::= SEQUENCE {
*/
csr->cri.p = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
}
end = p + len;
csr->cri.len = end - csr->cri.p;
/*
* Version ::= INTEGER { v1(0) }
*/
if( ( ret = x509_csr_get_version( &p, end, &csr->version ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( ret );
}
if( csr->version != 0 )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_UNKNOWN_VERSION );
}
csr->version++;
/*
* subject Name
*/
csr->subject_raw.p = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
}
if( ( ret = mbedtls_x509_get_name( &p, p + len, &csr->subject ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( ret );
}
csr->subject_raw.len = p - csr->subject_raw.p;
/*
* subjectPKInfo SubjectPublicKeyInfo
*/
if( ( ret = mbedtls_pk_parse_subpubkey( &p, end, &csr->pk ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( ret );
}
/*
* attributes [0] Attributes
*
* The list of possible attributes is open-ended, though RFC 2985
* (PKCS#9) defines a few in section 5.4. We currently don't support any,
* so we just ignore them. This is a safe thing to do as the worst thing
* that could happen is that we issue a certificate that does not match
* the requester's expectations - this cannot cause a violation of our
* signature policies.
*/
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
}
p += len;
end = csr->raw.p + csr->raw.len;
/*
* signatureAlgorithm AlgorithmIdentifier,
* signature BIT STRING
*/
if( ( ret = mbedtls_x509_get_alg( &p, end, &csr->sig_oid, &sig_params ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( ret );
}
if( ( ret = mbedtls_x509_get_sig_alg( &csr->sig_oid, &sig_params,
&csr->sig_md, &csr->sig_pk,
&csr->sig_opts ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG );
}
if( ( ret = mbedtls_x509_get_sig( &p, end, &csr->sig ) ) != 0 )
{
mbedtls_x509_csr_free( csr );
return( ret );
}
if( p != end )
{
mbedtls_x509_csr_free( csr );
return( MBEDTLS_ERR_X509_INVALID_FORMAT +
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
}
return( 0 );
}
/*
* Parse a CSR, allowing for PEM or raw DER encoding
*/
int mbedtls_x509_csr_parse( mbedtls_x509_csr *csr, const unsigned char *buf, size_t buflen )
{
#if defined(MBEDTLS_PEM_PARSE_C)
int ret;
size_t use_len;
mbedtls_pem_context pem;
#endif
/*
* Check for valid input
*/
if( csr == NULL || buf == NULL || buflen == 0 )
return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
#if defined(MBEDTLS_PEM_PARSE_C)
mbedtls_pem_init( &pem );
/* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */
if( buf[buflen - 1] != '\0' )
ret = MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
else
ret = mbedtls_pem_read_buffer( &pem,
"-----BEGIN CERTIFICATE REQUEST-----",
"-----END CERTIFICATE REQUEST-----",
buf, NULL, 0, &use_len );
if( ret == 0 )
{
/*
* Was PEM encoded, parse the result
*/
if( ( ret = mbedtls_x509_csr_parse_der( csr, pem.buf, pem.buflen ) ) != 0 )
return( ret );
mbedtls_pem_free( &pem );
return( 0 );
}
else if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
{
mbedtls_pem_free( &pem );
return( ret );
}
else
#endif /* MBEDTLS_PEM_PARSE_C */
return( mbedtls_x509_csr_parse_der( csr, buf, buflen ) );
}
#if defined(MBEDTLS_FS_IO)
/*
* Load a CSR into the structure
*/
int mbedtls_x509_csr_parse_file( mbedtls_x509_csr *csr, const char *path )
{
int ret;
size_t n;
unsigned char *buf;
if( ( ret = mbedtls_pk_load_file( path, &buf, &n ) ) != 0 )
return( ret );
ret = mbedtls_x509_csr_parse( csr, buf, n );
mbedtls_zeroize( buf, n );
mbedtls_free( buf );
return( ret );
}
#endif /* MBEDTLS_FS_IO */
#define BEFORE_COLON 14
#define BC "14"
/*
* Return an informational string about the CSR.
*/
int mbedtls_x509_csr_info( char *buf, size_t size, const char *prefix,
const mbedtls_x509_csr *csr )
{
int ret;
size_t n;
char *p;
char key_size_str[BEFORE_COLON];
p = buf;
n = size;
ret = mbedtls_snprintf( p, n, "%sCSR version : %d",
prefix, csr->version );
MBEDTLS_X509_SAFE_SNPRINTF;
ret = mbedtls_snprintf( p, n, "\n%ssubject name : ", prefix );
MBEDTLS_X509_SAFE_SNPRINTF;
ret = mbedtls_x509_dn_gets( p, n, &csr->subject );
MBEDTLS_X509_SAFE_SNPRINTF;
ret = mbedtls_snprintf( p, n, "\n%ssigned using : ", prefix );
MBEDTLS_X509_SAFE_SNPRINTF;
ret = mbedtls_x509_sig_alg_gets( p, n, &csr->sig_oid, csr->sig_pk, csr->sig_md,
csr->sig_opts );
MBEDTLS_X509_SAFE_SNPRINTF;
if( ( ret = mbedtls_x509_key_size_helper( key_size_str, BEFORE_COLON,
mbedtls_pk_get_name( &csr->pk ) ) ) != 0 )
{
return( ret );
}
ret = mbedtls_snprintf( p, n, "\n%s%-" BC "s: %d bits\n", prefix, key_size_str,
(int) mbedtls_pk_get_bitlen( &csr->pk ) );
MBEDTLS_X509_SAFE_SNPRINTF;
return( (int) ( size - n ) );
}
/*
* Initialize a CSR
*/
void mbedtls_x509_csr_init( mbedtls_x509_csr *csr )
{
memset( csr, 0, sizeof(mbedtls_x509_csr) );
}
/*
* Unallocate all CSR data
*/
void mbedtls_x509_csr_free( mbedtls_x509_csr *csr )
{
mbedtls_x509_name *name_cur;
mbedtls_x509_name *name_prv;
if( csr == NULL )
return;
mbedtls_pk_free( &csr->pk );
#if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
mbedtls_free( csr->sig_opts );
#endif
name_cur = csr->subject.next;
while( name_cur != NULL )
{
name_prv = name_cur;
name_cur = name_cur->next;
mbedtls_zeroize( name_prv, sizeof( mbedtls_x509_name ) );
mbedtls_free( name_prv );
}
if( csr->raw.p != NULL )
{
mbedtls_zeroize( csr->raw.p, csr->raw.len );
mbedtls_free( csr->raw.p );
}
mbedtls_zeroize( csr, sizeof( mbedtls_x509_csr ) );
}
#endif /* MBEDTLS_X509_CSR_PARSE_C */
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