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mbedtls/library/asn1parse.c

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/*
* Generic ASN.1 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)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_ASN1_PARSE_C)
#include "mbedtls/asn1.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include <string.h>
#if defined(MBEDTLS_BIGNUM_C)
#include "mbedtls/bignum.h"
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
/*
* ASN.1 DER decoding routines
*/
int mbedtls_asn1_get_len( unsigned char **p,
const unsigned char *end,
size_t *len )
{
if( ( end - *p ) < 1 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
if( ( **p & 0x80 ) == 0 )
*len = *(*p)++;
else
{
switch( **p & 0x7F )
{
case 1:
if( ( end - *p ) < 2 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
*len = (*p)[1];
(*p) += 2;
break;
case 2:
if( ( end - *p ) < 3 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
*len = ( (size_t)(*p)[1] << 8 ) | (*p)[2];
(*p) += 3;
break;
case 3:
if( ( end - *p ) < 4 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
*len = ( (size_t)(*p)[1] << 16 ) |
( (size_t)(*p)[2] << 8 ) | (*p)[3];
(*p) += 4;
break;
case 4:
if( ( end - *p ) < 5 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
*len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) |
( (size_t)(*p)[3] << 8 ) | (*p)[4];
(*p) += 5;
break;
default:
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
}
}
if( *len > (size_t) ( end - *p ) )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
return( 0 );
}
int mbedtls_asn1_get_tag( unsigned char **p,
const unsigned char *end,
size_t *len, int tag )
{
if( ( end - *p ) < 1 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
if( **p != tag )
return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
(*p)++;
return( mbedtls_asn1_get_len( p, end, len ) );
}
int mbedtls_asn1_get_bool( unsigned char **p,
const unsigned char *end,
int *val )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 )
return( ret );
if( len != 1 )
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
*val = ( **p != 0 ) ? 1 : 0;
(*p)++;
return( 0 );
}
static int asn1_get_tagged_int( unsigned char **p,
const unsigned char *end,
int tag, int *val )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if( ( ret = mbedtls_asn1_get_tag( p, end, &len, tag ) ) != 0 )
return( ret );
/*
* len==0 is malformed (0 must be represented as 020100 for INTEGER,
* or 0A0100 for ENUMERATED tags
*/
if( len == 0 )
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
/* This is a cryptography library. Reject negative integers. */
if( ( **p & 0x80 ) != 0 )
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
/* Skip leading zeros. */
while( len > 0 && **p == 0 )
{
++( *p );
--len;
}
/* Reject integers that don't fit in an int. This code assumes that
* the int type has no padding bit. */
if( len > sizeof( int ) )
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
if( len == sizeof( int ) && ( **p & 0x80 ) != 0 )
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
*val = 0;
while( len-- > 0 )
{
*val = ( *val << 8 ) | **p;
(*p)++;
}
return( 0 );
}
int mbedtls_asn1_get_int( unsigned char **p,
const unsigned char *end,
int *val )
{
return( asn1_get_tagged_int( p, end, MBEDTLS_ASN1_INTEGER, val) );
}
int mbedtls_asn1_get_enum( unsigned char **p,
const unsigned char *end,
int *val )
{
return( asn1_get_tagged_int( p, end, MBEDTLS_ASN1_ENUMERATED, val) );
}
#if defined(MBEDTLS_BIGNUM_C)
int mbedtls_asn1_get_mpi( unsigned char **p,
const unsigned char *end,
mbedtls_mpi *X )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
return( ret );
ret = mbedtls_mpi_read_binary( X, *p, len );
*p += len;
return( ret );
}
#endif /* MBEDTLS_BIGNUM_C */
int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
mbedtls_asn1_bitstring *bs)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/* Certificate type is a single byte bitstring */
if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
return( ret );
/* Check length, subtract one for actual bit string length */
if( bs->len < 1 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
bs->len -= 1;
/* Get number of unused bits, ensure unused bits <= 7 */
bs->unused_bits = **p;
if( bs->unused_bits > 7 )
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
(*p)++;
/* Get actual bitstring */
bs->p = *p;
*p += bs->len;
if( *p != end )
return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
return( 0 );
}
/*
* Traverse an ASN.1 "SEQUENCE OF <tag>"
* and call a callback for each entry found.
*/
int mbedtls_asn1_traverse_sequence_of(
unsigned char **p,
const unsigned char *end,
uint8_t tag_must_mask, uint8_t tag_must_val,
uint8_t tag_may_mask, uint8_t tag_may_val,
int (*cb)( void *ctx, int tag,
unsigned char *start, size_t len ),
void *ctx )
{
int ret;
size_t len;
/* Get main sequence tag */
if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
{
return( ret );
}
if( *p + len != end )
return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
while( *p < end )
{
unsigned char const tag = *(*p)++;
if( ( tag & tag_must_mask ) != tag_must_val )
return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
if( ( ret = mbedtls_asn1_get_len( p, end, &len ) ) != 0 )
return( ret );
if( ( tag & tag_may_mask ) == tag_may_val )
{
if( cb != NULL )
{
ret = cb( ctx, tag, *p, len );
if( ret != 0 )
return( ret );
}
}
*p += len;
}
return( 0 );
}
/*
* Get a bit string without unused bits
*/
int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
size_t *len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
return( ret );
if( *len == 0 )
return( MBEDTLS_ERR_ASN1_INVALID_DATA );
--( *len );
if( **p != 0 )
return( MBEDTLS_ERR_ASN1_INVALID_DATA );
++( *p );
return( 0 );
}
void mbedtls_asn1_sequence_free( mbedtls_asn1_sequence *seq )
{
while( seq != NULL )
{
mbedtls_asn1_sequence *next = seq->next;
mbedtls_platform_zeroize( seq, sizeof( *seq ) );
mbedtls_free( seq );
seq = next;
}
}
typedef struct
{
int tag;
mbedtls_asn1_sequence *cur;
} asn1_get_sequence_of_cb_ctx_t;
static int asn1_get_sequence_of_cb( void *ctx,
int tag,
unsigned char *start,
size_t len )
{
asn1_get_sequence_of_cb_ctx_t *cb_ctx =
(asn1_get_sequence_of_cb_ctx_t *) ctx;
mbedtls_asn1_sequence *cur =
cb_ctx->cur;
if( cur->buf.p != NULL )
{
cur->next =
mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
if( cur->next == NULL )
return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
cur = cur->next;
}
cur->buf.p = start;
cur->buf.len = len;
cur->buf.tag = tag;
cb_ctx->cur = cur;
return( 0 );
}
/*
* Parses and splits an ASN.1 "SEQUENCE OF <tag>"
*/
int mbedtls_asn1_get_sequence_of( unsigned char **p,
const unsigned char *end,
mbedtls_asn1_sequence *cur,
int tag)
{
asn1_get_sequence_of_cb_ctx_t cb_ctx = { tag, cur };
memset( cur, 0, sizeof( mbedtls_asn1_sequence ) );
return( mbedtls_asn1_traverse_sequence_of(
p, end, 0xFF, tag, 0, 0,
asn1_get_sequence_of_cb, &cb_ctx ) );
}
int mbedtls_asn1_get_alg( unsigned char **p,
const unsigned char *end,
mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
return( ret );
if( ( end - *p ) < 1 )
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
alg->tag = **p;
end = *p + len;
if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 )
return( ret );
alg->p = *p;
*p += alg->len;
if( *p == end )
{
mbedtls_platform_zeroize( params, sizeof(mbedtls_asn1_buf) );
return( 0 );
}
params->tag = **p;
(*p)++;
if( ( ret = mbedtls_asn1_get_len( p, end, &params->len ) ) != 0 )
return( ret );
params->p = *p;
*p += params->len;
if( *p != end )
return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
return( 0 );
}
int mbedtls_asn1_get_alg_null( unsigned char **p,
const unsigned char *end,
mbedtls_asn1_buf *alg )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_asn1_buf params;
memset( &params, 0, sizeof(mbedtls_asn1_buf) );
if( ( ret = mbedtls_asn1_get_alg( p, end, alg, &params ) ) != 0 )
return( ret );
if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 )
return( MBEDTLS_ERR_ASN1_INVALID_DATA );
return( 0 );
}
void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur )
{
if( cur == NULL )
return;
mbedtls_free( cur->oid.p );
mbedtls_free( cur->val.p );
mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
}
void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
{
mbedtls_asn1_named_data *cur;
while( ( cur = *head ) != NULL )
{
*head = cur->next;
mbedtls_asn1_free_named_data( cur );
mbedtls_free( cur );
}
}
mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
const char *oid, size_t len )
{
while( list != NULL )
{
if( list->oid.len == len &&
memcmp( list->oid.p, oid, len ) == 0 )
{
break;
}
list = list->next;
}
return( list );
}
#endif /* MBEDTLS_ASN1_PARSE_C */
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