libcrypto/asn1/tasn_utl.c

/* $OpenBSD: tasn_utl.c,v 1.18 2022/12/26 07:18:51 jmc Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project 2000.
 */
/* ====================================================================
 * Copyright (c) 2000-2004 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <limits.h>
#include <stddef.h>
#include <string.h>

#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include <openssl/objects.h>
#include <openssl/err.h>

#include "bytestring.h"

/* Utility functions for manipulating fields and offsets */

/* Add 'offset' to 'addr' */
#define offset2ptr(addr, offset) (void *)(((char *) addr) + offset)

/* Given an ASN1_ITEM CHOICE type return
 * the selector value
 */

int
asn1_get_choice_selector(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
	int *sel = offset2ptr(*pval, it->utype);
	return *sel;
}

/* Given an ASN1_ITEM CHOICE type set
 * the selector value, return old value.
 */

int
asn1_set_choice_selector(ASN1_VALUE **pval, int value, const ASN1_ITEM *it)
{
	int *sel, ret;
	sel = offset2ptr(*pval, it->utype);
	ret = *sel;
	*sel = value;
	return ret;
}

/* Do reference counting. The value 'op' decides what to do.
 * if it is +1 then the count is incremented. If op is 0 count is
 * set to 1. If op is -1 count is decremented and the return value
 * is the current reference count or 0 if no reference count exists.
 */

int
asn1_do_lock(ASN1_VALUE **pval, int op, const ASN1_ITEM *it)
{
	const ASN1_AUX *aux;
	int *lck, ret;

	if ((it->itype != ASN1_ITYPE_SEQUENCE) &&
	    (it->itype != ASN1_ITYPE_NDEF_SEQUENCE))
		return 0;
	aux = it->funcs;
	if (!aux || !(aux->flags & ASN1_AFLG_REFCOUNT))
		return 0;
	lck = offset2ptr(*pval, aux->ref_offset);
	if (op == 0) {
		*lck = 1;
		return 1;
	}
	ret = CRYPTO_add(lck, op, aux->ref_lock);
	return ret;
}

static ASN1_ENCODING *
asn1_get_enc_ptr(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
	const ASN1_AUX *aux = it->funcs;

	if (pval == NULL || *pval == NULL)
		return NULL;

	if (aux == NULL || (aux->flags & ASN1_AFLG_ENCODING) == 0)
		return NULL;

	return offset2ptr(*pval, aux->enc_offset);
}

void
asn1_enc_init(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
	ASN1_ENCODING *aenc;

	if ((aenc = asn1_get_enc_ptr(pval, it)) == NULL)
		return;

	aenc->enc = NULL;
	aenc->len = 0;
	aenc->modified = 1;
}

static void
asn1_enc_clear(ASN1_ENCODING *aenc)
{
	freezero(aenc->enc, aenc->len);
	aenc->enc = NULL;
	aenc->len = 0;
	aenc->modified = 1;
}

void
asn1_enc_cleanup(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
	ASN1_ENCODING *aenc;

	if ((aenc = asn1_get_enc_ptr(pval, it)) == NULL)
		return;

	asn1_enc_clear(aenc);
}

int
asn1_enc_save(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it)
{
	ASN1_ENCODING *aenc;
	uint8_t *data = NULL;
	size_t data_len = 0;

	if ((aenc = asn1_get_enc_ptr(pval, it)) == NULL)
		return 1;

	asn1_enc_clear(aenc);

	if (!CBS_stow(cbs, &data, &data_len))
		return 0;
	if (data_len > LONG_MAX) {
		freezero(data, data_len);
		return 0;
	}

	aenc->enc = data;
	aenc->len = (long)data_len;
	aenc->modified = 0;

	return 1;
}

int
asn1_enc_restore(int *out_len, unsigned char **out, ASN1_VALUE **pval,
    const ASN1_ITEM *it)
{
	ASN1_ENCODING *aenc;

	if ((aenc = asn1_get_enc_ptr(pval, it)) == NULL)
		return 0;

	if (aenc->modified)
		return 0;

	if (out != NULL) {
		memcpy(*out, aenc->enc, aenc->len);
		*out += aenc->len;
	}

	if (out_len != NULL)
		*out_len = aenc->len;

	return 1;
}

/* Given an ASN1_TEMPLATE get a pointer to a field */
ASN1_VALUE **
asn1_get_field_ptr(ASN1_VALUE **pval, const ASN1_TEMPLATE *tt)
{
	ASN1_VALUE **pvaltmp;

	pvaltmp = offset2ptr(*pval, tt->offset);
	/* NOTE for BOOLEAN types the field is just a plain
 	 * int so we can't return int **, so settle for
	 * (int *).
	 */
	return pvaltmp;
}

/* Handle ANY DEFINED BY template, find the selector, look up
 * the relevant ASN1_TEMPLATE in the table and return it.
 */

const ASN1_TEMPLATE *
asn1_do_adb(ASN1_VALUE **pval, const ASN1_TEMPLATE *tt, int nullerr)
{
	const ASN1_ADB *adb;
	const ASN1_ADB_TABLE *atbl;
	long selector;
	ASN1_VALUE **sfld;
	int i;

	if (!(tt->flags & ASN1_TFLG_ADB_MASK))
		return tt;

	/* Else ANY DEFINED BY ... get the table */
	adb = (const ASN1_ADB *)tt->item;

	/* Get the selector field */
	sfld = offset2ptr(*pval, adb->offset);

	/* Check if NULL */
	if (!sfld) {
		if (!adb->null_tt)
			goto err;
		return adb->null_tt;
	}

	/* Convert type to a long:
	 * NB: don't check for NID_undef here because it
	 * might be a legitimate value in the table
	 */
	if (tt->flags & ASN1_TFLG_ADB_OID)
		selector = OBJ_obj2nid((ASN1_OBJECT *)*sfld);
	else
		selector = ASN1_INTEGER_get((ASN1_INTEGER *)*sfld);

	/* Try to find matching entry in table
	 * Maybe should check application types first to
	 * allow application override? Might also be useful
	 * to have a flag which indicates table is sorted and
	 * we can do a binary search. For now stick to a
	 * linear search.
	 */

	for (atbl = adb->tbl, i = 0; i < adb->tblcount; i++, atbl++)
		if (atbl->value == selector)
			return &atbl->tt;

	/* FIXME: need to search application table too */

	/* No match, return default type */
	if (!adb->default_tt)
		goto err;
	return adb->default_tt;

 err:
	/* FIXME: should log the value or OID of unsupported type */
	if (nullerr)
		ASN1error(ASN1_R_UNSUPPORTED_ANY_DEFINED_BY_TYPE);
	return NULL;
}