lib/libgss/g_imp_name.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 *  glue routine gss_import_name
 *
 */

#include <mechglueP.h>
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <string.h>
#include <errno.h>

extern int
get_der_length(unsigned char **, unsigned int, unsigned int *);

/* local function to import GSS_C_EXPORT_NAME names */
static OM_uint32 importExportName(OM_uint32 *, gss_union_name_t);

static OM_uint32
val_imp_name_args(
	OM_uint32 *minor_status,
	gss_buffer_t input_name_buffer,
	gss_name_t *output_name)
{

	/* Initialize outputs. */

	if (minor_status != NULL)
		*minor_status = 0;

	if (output_name != NULL)
		*output_name = GSS_C_NO_NAME;

	/* Validate arguments. */

	if (minor_status == NULL)
		return (GSS_S_CALL_INACCESSIBLE_WRITE);

	if (output_name == NULL)
		return (GSS_S_CALL_INACCESSIBLE_WRITE);

	if (input_name_buffer == GSS_C_NO_BUFFER)
		return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);

	if (GSS_EMPTY_BUFFER(input_name_buffer))
		return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);

	return (GSS_S_COMPLETE);
}

OM_uint32
gss_import_name(minor_status,
		input_name_buffer,
		input_name_type,
		output_name)

OM_uint32 *minor_status;
const gss_buffer_t input_name_buffer;
const gss_OID input_name_type;
gss_name_t *output_name;
{
	gss_union_name_t union_name;
	OM_uint32 major_status = GSS_S_FAILURE, tmp;

	major_status = val_imp_name_args(minor_status,
					input_name_buffer,
					output_name);
	if (major_status != GSS_S_COMPLETE)
		return (major_status);

	/*
	 * First create the union name struct that will hold the external
	 * name and the name type.
	 */
	union_name = (gss_union_name_t)malloc(sizeof (gss_union_name_desc));
	if (!union_name)
		return (GSS_S_FAILURE);

	union_name->mech_type = 0;
	union_name->mech_name = 0;
	union_name->name_type = 0;
	union_name->external_name = 0;

	/*
	 * All we do here is record the external name and name_type.
	 * When the name is actually used, the underlying gss_import_name()
	 * is called for the appropriate mechanism.  The exception to this
	 * rule is when the name of GSS_C_NT_EXPORT_NAME type.  If that is
	 * the case, then we make it MN in this call.
	 */
	major_status = gssint_create_copy_buffer(input_name_buffer,
					&union_name->external_name, 0);
	if (major_status != GSS_S_COMPLETE) {
		free(union_name);
		return (major_status);
	}

	if (input_name_type != GSS_C_NULL_OID) {
		major_status = generic_gss_copy_oid(minor_status,
						input_name_type,
						&union_name->name_type);
		if (major_status != GSS_S_COMPLETE)
			goto allocation_failure;
	}

	/*
	 * In MIT Distribution the mechanism is determined from the nametype;
	 * This is not a good idea - first mechanism that supports a given
	 * name type is picked up; later on the caller can request a
	 * different mechanism. So we don't determine the mechanism here. Now
	 * the user level and kernel level import_name routine looks similar
	 * except the kernel routine makes a copy of the nametype structure. We
	 * do however make this an MN for names of GSS_C_NT_EXPORT_NAME type.
	 */
	if (input_name_type != GSS_C_NULL_OID &&
	    g_OID_equal(input_name_type, GSS_C_NT_EXPORT_NAME)) {
		major_status = importExportName(minor_status, union_name);
		if (major_status != GSS_S_COMPLETE)
			goto allocation_failure;
	}

	*output_name = (gss_name_t)union_name;
	return (GSS_S_COMPLETE);

allocation_failure:
	if (union_name) {
		if (union_name->external_name) {
			if (union_name->external_name->value)
				free(union_name->external_name->value);
			free(union_name->external_name);
		}
		if (union_name->name_type)
			(void) generic_gss_release_oid(&tmp,
						    &union_name->name_type);
		if (union_name->mech_name)
			(void) __gss_release_internal_name(minor_status,
						union_name->mech_type,
						&union_name->mech_name);
		if (union_name->mech_type)
			(void) generic_gss_release_oid(&tmp,
						    &union_name->mech_type);
		free(union_name);
	}
	return (major_status);
}


/*
 * GSS export name constants
 */
static const char *expNameTokId = "\x04\x01";
static const int expNameTokIdLen = 2;
static const int mechOidLenLen = 2;
static const int nameTypeLenLen = 2;

static OM_uint32
importExportName(minor, unionName)
OM_uint32 *minor;
gss_union_name_t unionName;
{
	gss_OID_desc mechOid;
	gss_buffer_desc expName;
	unsigned char *buf;
	gss_mechanism mech;
	OM_uint32 major, mechOidLen, nameLen, curLength;
	unsigned int bytes;

	expName.value = unionName->external_name->value;
	expName.length = unionName->external_name->length;

	curLength = expNameTokIdLen + mechOidLenLen;
	if (expName.length < curLength)
		return (GSS_S_DEFECTIVE_TOKEN);

	buf = (unsigned char *)expName.value;
	if (memcmp(expNameTokId, buf, expNameTokIdLen) != 0)
		return (GSS_S_DEFECTIVE_TOKEN);

	buf += expNameTokIdLen;

	/* extract the mechanism oid length */
	mechOidLen = (*buf++ << 8);
	mechOidLen |= (*buf++);
	curLength += mechOidLen;
	if (expName.length < curLength)
		return (GSS_S_DEFECTIVE_TOKEN);
	/*
	 * The mechOid itself is encoded in DER format, OID Tag (0x06)
	 * length and the value of mech_OID
	 */
	if (*buf++ != 0x06)
		return (GSS_S_DEFECTIVE_TOKEN);

	/*
	 * mechoid Length is encoded twice; once in 2 bytes as
	 * explained in RFC2743 (under mechanism independent exported
	 * name object format) and once using DER encoding
	 *
	 * We verify both lengths.
	 */

	mechOid.length = get_der_length(&buf,
				(expName.length - curLength), &bytes);
	mechOid.elements = (void *)buf;

	/*
	 * 'bytes' is the length of the DER length, '1' is for the DER
	 * tag for OID
	 */
	if ((bytes + mechOid.length + 1) != mechOidLen)
		return (GSS_S_DEFECTIVE_TOKEN);

	buf += mechOid.length;
	if ((mech = __gss_get_mechanism(&mechOid)) == NULL)
		return (GSS_S_BAD_MECH);

	if (mech->gss_import_name == NULL)
		return (GSS_S_UNAVAILABLE);

	/*
	 * we must now determine if we should unwrap the name ourselves
	 * or make the mechanism do it - we should only unwrap it
	 * if we create it; so if mech->gss_export_name == NULL, we must
	 * have created it.
	 */
	if (mech->gss_export_name) {
		if ((major = mech->gss_import_name(mech->context, minor,
				&expName, (gss_OID)GSS_C_NT_EXPORT_NAME,
				&unionName->mech_name)) != GSS_S_COMPLETE ||
			(major = generic_gss_copy_oid(minor, &mechOid,
					&unionName->mech_type)) !=
				GSS_S_COMPLETE) {
			return (major);
		}
		return (major);
	}
	/*
	 * we must have exported the name - so we now need to reconstruct it
	 * and call the mechanism to create it
	 *
	 * WARNING:	Older versions of __gss_export_internal_name() did
	 *		not export names correctly, but now it does.  In
	 *		order to stay compatible with existing exported
	 *		names we must support names exported the broken
	 *		way.
	 *
	 * Specifically, __gss_export_internal_name() used to include
	 * the name type OID in the encoding of the exported MN.
	 * Additionally, the Kerberos V mech used to make display names
	 * that included a null terminator which was counted in the
	 * display name gss_buffer_desc.
	 */
	curLength += 4;		/* 4 bytes for name len */
	if (expName.length < curLength)
		return (GSS_S_DEFECTIVE_TOKEN);

	/* next 4 bytes in the name are the name length */
	nameLen = (*buf++) << 24;
	nameLen |= (*buf++ << 16);
	nameLen |= (*buf++ << 8);
	nameLen |= (*buf++);

	/*
	 * we use < here because bad code in rpcsec_gss rounds up exported
	 * name token lengths and pads with nulls, otherwise != would be
	 * appropriate
	 */
	curLength += nameLen;   /* this is the total length */
	if (expName.length < curLength)
		return (GSS_S_DEFECTIVE_TOKEN);

	/*
	 * We detect broken exported names here: they always start with
	 * a two-octet network-byte order OID length, which is always
	 * less than 256 bytes, so the first octet of the length is
	 * always '\0', which is not allowed in GSS-API display names
	 * (or never occurs in them anyways).  Of course, the OID
	 * shouldn't be there, but it is.  After the OID (sans DER tag
	 * and length) there's the name itself, though null-terminated;
	 * this null terminator should also not be there, but it is.
	 */
	if (nameLen > 0 && *buf == '\0') {
		OM_uint32 nameTypeLen;
		/* next two bytes are the name oid */
		if (nameLen < nameTypeLenLen)
			return (GSS_S_DEFECTIVE_TOKEN);

		nameLen -= nameTypeLenLen;

		nameTypeLen = (*buf++) << 8;
		nameTypeLen |= (*buf++);

		if (nameLen < nameTypeLen)
			return (GSS_S_DEFECTIVE_TOKEN);

		buf += nameTypeLen;
		nameLen -= nameTypeLen;

		/*
		 * adjust for expected null terminator that should
		 * really not be there
		 */
		if (nameLen > 0 && *(buf + nameLen - 1) == '\0')
			nameLen--;
	}

	/*
	 * Can a name be null?  Let the mech decide.
	 *
	 * NOTE: We use GSS_C_NULL_OID as the name type when importing
	 *	 the unwrapped name.  Presumably the exported name had,
	 *	 prior to being exported been obtained in such a way
	 *	 that it has been properly perpared ("canonicalized," in
	 *	 GSS-API terms) accroding to some name type; we cannot
	 *	 tell what that name type was now, but the name should
	 *	 need no further preparation other than the lowest
	 *	 common denominator afforded by the mech to names
	 *	 imported with GSS_C_NULL_OID.  For the Kerberos V mech
	 *	 this means doing less busywork too (particularly once
	 *	 IDN is thrown in with Kerberos V extensions).
	 */
	expName.length = nameLen;
	expName.value = nameLen ? (void *)buf : NULL;
	major = mech->gss_import_name(mech->context, minor, &expName,
			    GSS_C_NULL_OID, &unionName->mech_name);
	if (major != GSS_S_COMPLETE)
		return (major);

	return (generic_gss_copy_oid(minor, &mechOid, &unionName->mech_type));
} /* importExportName */