/*	$NetBSD: gss_aeap.c,v 1.2 2017/01/28 21:31:46 christos Exp $	*/

/*
 * AEAD support
 */

#include "mech_locl.h"

/**
 * Encrypts or sign the data.
 *
 * This is a more complicated version of gss_wrap(), it allows the
 * caller to use AEAD data (signed header/trailer) and allow greater
 * controll over where the encrypted data is placed.
 *
 * The maximum packet size is gss_context_stream_sizes.max_msg_size.
 *
 * The caller needs provide the folloing buffers when using in conf_req_flag=1 mode:
 *
 * - HEADER (of size gss_context_stream_sizes.header)
 *   { DATA or SIGN_ONLY } (optional, zero or more)
 *   PADDING (of size gss_context_stream_sizes.blocksize, if zero padding is zero, can be omitted)
 *   TRAILER (of size gss_context_stream_sizes.trailer)
 *
 * - on DCE-RPC mode, the caller can skip PADDING and TRAILER if the
 *   DATA elements is padded to a block bountry and header is of at
 *   least size gss_context_stream_sizes.header + gss_context_stream_sizes.trailer.
 *
 * HEADER, PADDING, TRAILER will be shrunken to the size required to transmit any of them too large.
 *
 * To generate gss_wrap() compatible packets, use: HEADER | DATA | PADDING | TRAILER
 *
 * When used in conf_req_flag=0,
 *
 * - HEADER (of size gss_context_stream_sizes.header)
 *   { DATA or SIGN_ONLY } (optional, zero or more)
 *   PADDING (of size gss_context_stream_sizes.blocksize, if zero padding is zero, can be omitted)
 *   TRAILER (of size gss_context_stream_sizes.trailer)
 *
 *
 * The input sizes of HEADER, PADDING and TRAILER can be fetched using gss_wrap_iov_length() or
 * gss_context_query_attributes().
 *
 * @ingroup gssapi
 */


GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_wrap_iov(OM_uint32 * minor_status,
	     gss_ctx_id_t  context_handle,
	     int conf_req_flag,
	     gss_qop_t qop_req,
	     int * conf_state,
	     gss_iov_buffer_desc *iov,
	     int iov_count)
{
	struct _gss_context *ctx = (struct _gss_context *) context_handle;
	gssapi_mech_interface m;

	if (minor_status)
	    *minor_status = 0;
	if (conf_state)
	    *conf_state = 0;
	if (ctx == NULL)
	    return GSS_S_NO_CONTEXT;
	if (iov == NULL && iov_count != 0)
	    return GSS_S_CALL_INACCESSIBLE_READ;

	m = ctx->gc_mech;

	if (m->gm_wrap_iov == NULL)
	    return GSS_S_UNAVAILABLE;

	return (m->gm_wrap_iov)(minor_status, ctx->gc_ctx,
				conf_req_flag, qop_req, conf_state,
				iov, iov_count);
}

/**
 * Decrypt or verifies the signature on the data.
 *
 *
 * @ingroup gssapi
 */

GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_unwrap_iov(OM_uint32 *minor_status,
	       gss_ctx_id_t context_handle,
	       int *conf_state,
	       gss_qop_t *qop_state,
	       gss_iov_buffer_desc *iov,
	       int iov_count)
{
	struct _gss_context *ctx = (struct _gss_context *) context_handle;
	gssapi_mech_interface m;

	if (minor_status)
	    *minor_status = 0;
	if (conf_state)
	    *conf_state = 0;
	if (qop_state)
	    *qop_state = 0;
	if (ctx == NULL)
	    return GSS_S_NO_CONTEXT;
	if (iov == NULL && iov_count != 0)
	    return GSS_S_CALL_INACCESSIBLE_READ;

	m = ctx->gc_mech;

	if (m->gm_unwrap_iov == NULL)
	    return GSS_S_UNAVAILABLE;

	return (m->gm_unwrap_iov)(minor_status, ctx->gc_ctx,
				  conf_state, qop_state,
				  iov, iov_count);
}

/**
 * Update the length fields in iov buffer for the types:
 * - GSS_IOV_BUFFER_TYPE_HEADER
 * - GSS_IOV_BUFFER_TYPE_PADDING
 * - GSS_IOV_BUFFER_TYPE_TRAILER
 *
 * Consider using gss_context_query_attributes() to fetch the data instead.
 *
 * @ingroup gssapi
 */

GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_wrap_iov_length(OM_uint32 * minor_status,
		    gss_ctx_id_t context_handle,
		    int conf_req_flag,
		    gss_qop_t qop_req,
		    int *conf_state,
		    gss_iov_buffer_desc *iov,
		    int iov_count)
{
	struct _gss_context *ctx = (struct _gss_context *) context_handle;
	gssapi_mech_interface m;

	if (minor_status)
	    *minor_status = 0;
	if (conf_state)
	    *conf_state = 0;
	if (ctx == NULL)
	    return GSS_S_NO_CONTEXT;
	if (iov == NULL && iov_count != 0)
	    return GSS_S_CALL_INACCESSIBLE_READ;

	m = ctx->gc_mech;

	if (m->gm_wrap_iov_length == NULL)
	    return GSS_S_UNAVAILABLE;

	return (m->gm_wrap_iov_length)(minor_status, ctx->gc_ctx,
				       conf_req_flag, qop_req, conf_state,
				       iov, iov_count);
}

/**
 * Free all buffer allocated by gss_wrap_iov() or gss_unwrap_iov() by
 * looking at the GSS_IOV_BUFFER_FLAG_ALLOCATED flag.
 *
 * @ingroup gssapi
 */

GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_release_iov_buffer(OM_uint32 *minor_status,
		       gss_iov_buffer_desc *iov,
		       int iov_count)
{
    OM_uint32 junk;
    int i;

    if (minor_status)
	*minor_status = 0;
    if (iov == NULL && iov_count != 0)
	return GSS_S_CALL_INACCESSIBLE_READ;

    for (i = 0; i < iov_count; i++) {
	if ((iov[i].type & GSS_IOV_BUFFER_FLAG_ALLOCATED) == 0)
	    continue;
	gss_release_buffer(&junk, &iov[i].buffer);
	iov[i].type &= ~GSS_IOV_BUFFER_FLAG_ALLOCATED;
    }
    return GSS_S_COMPLETE;
}

/**
 * Query the context for parameters.
 *
 * SSPI equivalent if this function is QueryContextAttributes.
 *
 * - GSS_C_ATTR_STREAM_SIZES data is a gss_context_stream_sizes.
 *
 * @ingroup gssapi
 */

gss_OID_desc GSSAPI_LIB_FUNCTION __gss_c_attr_stream_sizes_oid_desc =
    {10, rk_UNCONST("\x2a\x86\x48\x86\xf7\x12\x01\x02\x01\x03")};

GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_context_query_attributes(OM_uint32 *minor_status,
			     gss_const_ctx_id_t context_handle,
			     const gss_OID attribute,
			     void *data,
			     size_t len)
{
    if (minor_status)
	*minor_status = 0;

    if (gss_oid_equal(GSS_C_ATTR_STREAM_SIZES, attribute)) {
	memset(data, 0, len);
	return GSS_S_COMPLETE;
    }

    return GSS_S_FAILURE;
}

/*
 * AEAD wrap API for a single piece of associated data, for compatibility
 * with MIT and as specified by draft-howard-gssapi-aead-00.txt.
 *
 * @ingroup gssapi
 */
GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_wrap_aead(OM_uint32 *minor_status,
	      gss_ctx_id_t context_handle,
              int conf_req_flag,
              gss_qop_t qop_req,
              gss_buffer_t input_assoc_buffer,
              gss_buffer_t input_payload_buffer,
              int *conf_state,
              gss_buffer_t output_message_buffer)
{
    OM_uint32 major_status, tmp, flags = 0;
    gss_iov_buffer_desc iov[5];
    size_t i;
    unsigned char *p;

    memset(iov, 0, sizeof(iov));

    iov[0].type = GSS_IOV_BUFFER_TYPE_HEADER;

    iov[1].type = GSS_IOV_BUFFER_TYPE_SIGN_ONLY;
    if (input_assoc_buffer)
	iov[1].buffer = *input_assoc_buffer;

    iov[2].type = GSS_IOV_BUFFER_TYPE_DATA;
    if (input_payload_buffer)
	iov[2].buffer.length = input_payload_buffer->length;

    gss_inquire_context(minor_status, context_handle, NULL, NULL,
			NULL, NULL, &flags, NULL, NULL);

    /* krb5 mech rejects padding/trailer if DCE-style is set */
    iov[3].type = (flags & GSS_C_DCE_STYLE) ? GSS_IOV_BUFFER_TYPE_EMPTY
					    : GSS_IOV_BUFFER_TYPE_PADDING;
    iov[4].type = (flags & GSS_C_DCE_STYLE) ? GSS_IOV_BUFFER_TYPE_EMPTY
					    : GSS_IOV_BUFFER_TYPE_TRAILER;

    major_status = gss_wrap_iov_length(minor_status, context_handle,
				       conf_req_flag, qop_req, conf_state,
				       iov, 5);
    if (GSS_ERROR(major_status))
	return major_status;

    for (i = 0, output_message_buffer->length = 0; i < 5; i++) {
        if (GSS_IOV_BUFFER_TYPE(iov[i].type) == GSS_IOV_BUFFER_TYPE_SIGN_ONLY)
	    continue;

	output_message_buffer->length += iov[i].buffer.length;
    }

    output_message_buffer->value = malloc(output_message_buffer->length);
    if (output_message_buffer->value == NULL) {
	*minor_status = ENOMEM;
	return GSS_S_FAILURE;
    }

    for (i = 0, p = output_message_buffer->value; i < 5; i++) {
	if (GSS_IOV_BUFFER_TYPE(iov[i].type) == GSS_IOV_BUFFER_TYPE_SIGN_ONLY)
	    continue;
	else if (GSS_IOV_BUFFER_TYPE(iov[i].type) == GSS_IOV_BUFFER_TYPE_DATA)
	    memcpy(p, input_payload_buffer->value, input_payload_buffer->length);

	iov[i].buffer.value = p;
	p += iov[i].buffer.length;
    }

    major_status = gss_wrap_iov(minor_status, context_handle, conf_req_flag,
				qop_req, conf_state, iov, 5);
    if (GSS_ERROR(major_status))
        gss_release_buffer(&tmp, output_message_buffer);

    return major_status;
}

/*
 * AEAD unwrap for a single piece of associated data, for compatibility
 * with MIT and as specified by draft-howard-gssapi-aead-00.txt.
 *
 * @ingroup gssapi
 */
GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_CALL
gss_unwrap_aead(OM_uint32 *minor_status,
		gss_ctx_id_t context_handle,
		gss_buffer_t input_message_buffer,
		gss_buffer_t input_assoc_buffer,
		gss_buffer_t output_payload_buffer,
		int *conf_state,
		gss_qop_t *qop_state)
{
    OM_uint32 major_status, tmp;
    gss_iov_buffer_desc iov[3];

    memset(iov, 0, sizeof(iov));

    iov[0].type = GSS_IOV_BUFFER_TYPE_STREAM;
    iov[0].buffer = *input_message_buffer;

    iov[1].type = GSS_IOV_BUFFER_TYPE_SIGN_ONLY;
    if (input_assoc_buffer)
	iov[1].buffer = *input_assoc_buffer;

    iov[2].type = GSS_IOV_BUFFER_TYPE_DATA | GSS_IOV_BUFFER_FLAG_ALLOCATE;

    major_status = gss_unwrap_iov(minor_status, context_handle, conf_state,
				  qop_state, iov, 3);
    if (GSS_ERROR(major_status))
	gss_release_iov_buffer(&tmp, &iov[2], 1);
    else
	*output_payload_buffer = iov[2].buffer;

    return major_status;
}