lib/dns/gssapi_link.c

	gssapi_link.c revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
/*
 * Copyright (C) 2000-2002, 2004-2009, 2011-2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/*
 * $Id: gssapi_link.c,v 1.17 2011/03/28 05:32:16 marka Exp $
 */

#include <config.h>

#ifdef GSSAPI

#include <isc/base64.h>
#include <isc/buffer.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dst/result.h>

#include "dst_internal.h"
#include "dst_parse.h"

#include <dst/gssapi.h>

#define INITIAL_BUFFER_SIZE 1024
#define BUFFER_EXTRA 1024

#define REGION_TO_GBUFFER(r, gb) \
    do { \
        (gb).length = (r).length; \
        (gb).value = (r).base; \
    } while (0)

#define GBUFFER_TO_REGION(gb, r) \
    do { \
      (r).length = (unsigned int)(gb).length; \
        (r).base = (gb).value; \
    } while (0)


struct dst_gssapi_signverifyctx {
    isc_buffer_t *buffer;
};

/*%
 * Allocate a temporary "context" for use in gathering data for signing
 * or verifying.
 */
static isc_result_t
gssapi_create_signverify_ctx(dst_key_t *key, dst_context_t *dctx) {
    dst_gssapi_signverifyctx_t *ctx;
    isc_result_t result;

    UNUSED(key);

    ctx = isc_mem_get(dctx->mctx, sizeof(dst_gssapi_signverifyctx_t));
    if (ctx == NULL)
        return (ISC_R_NOMEMORY);
    ctx->buffer = NULL;
    result = isc_buffer_allocate(dctx->mctx, &ctx->buffer,
                     INITIAL_BUFFER_SIZE);
    if (result != ISC_R_SUCCESS) {
        isc_mem_put(dctx->mctx, ctx, sizeof(dst_gssapi_signverifyctx_t));
        return (result);
    }

    dctx->ctxdata.gssctx = ctx;

    return (ISC_R_SUCCESS);
}

/*%
 * Destroy the temporary sign/verify context.
 */
static void
gssapi_destroy_signverify_ctx(dst_context_t *dctx) {
    dst_gssapi_signverifyctx_t *ctx = dctx->ctxdata.gssctx;

    if (ctx != NULL) {
        if (ctx->buffer != NULL)
            isc_buffer_free(&ctx->buffer);
        isc_mem_put(dctx->mctx, ctx, sizeof(dst_gssapi_signverifyctx_t));
        dctx->ctxdata.gssctx = NULL;
    }
}

/*%
 * Add data to our running buffer of data we will be signing or verifying.
 * This code will see if the new data will fit in our existing buffer, and
 * copy it in if it will.  If not, it will attempt to allocate a larger
 * buffer and copy old+new into it, and free the old buffer.
 */
static isc_result_t
gssapi_adddata(dst_context_t *dctx, const isc_region_t *data) {
    dst_gssapi_signverifyctx_t *ctx = dctx->ctxdata.gssctx;
    isc_buffer_t *newbuffer = NULL;
    isc_region_t r;
    unsigned int length;
    isc_result_t result;

    result = isc_buffer_copyregion(ctx->buffer, data);
    if (result == ISC_R_SUCCESS)
        return (ISC_R_SUCCESS);

    length = isc_buffer_length(ctx->buffer) + data->length + BUFFER_EXTRA;

    result = isc_buffer_allocate(dctx->mctx, &newbuffer, length);
    if (result != ISC_R_SUCCESS)
        return (result);

    isc_buffer_usedregion(ctx->buffer, &r);
    (void)isc_buffer_copyregion(newbuffer, &r);
    (void)isc_buffer_copyregion(newbuffer, data);

    isc_buffer_free(&ctx->buffer);
    ctx->buffer = newbuffer;

    return (ISC_R_SUCCESS);
}

/*%
 * Sign.
 */
static isc_result_t
gssapi_sign(dst_context_t *dctx, isc_buffer_t *sig) {
    dst_gssapi_signverifyctx_t *ctx = dctx->ctxdata.gssctx;
    isc_region_t message;
    gss_buffer_desc gmessage, gsig;
    OM_uint32 minor, gret;
    gss_ctx_id_t gssctx = dctx->key->keydata.gssctx;
    char buf[1024];

    /*
     * Convert the data we wish to sign into a structure gssapi can
     * understand.
     */
    isc_buffer_usedregion(ctx->buffer, &message);
    REGION_TO_GBUFFER(message, gmessage);

    /*
     * Generate the signature.
     */
    gret = gss_get_mic(&minor, gssctx, GSS_C_QOP_DEFAULT, &gmessage,
               &gsig);

    /*
     * If it did not complete, we log the result and return a generic
     * failure code.
     */
    if (gret != GSS_S_COMPLETE) {
        gss_log(3, "GSS sign error: %s",
            gss_error_tostring(gret, minor, buf, sizeof(buf)));
        return (ISC_R_FAILURE);
    }

    /*
     * If it will not fit in our allocated buffer, return that we need
     * more space.
     */
    if (gsig.length > isc_buffer_availablelength(sig)) {
        gss_release_buffer(&minor, &gsig);
        return (ISC_R_NOSPACE);
    }

    /*
     * Copy the output into our buffer space, and release the gssapi
     * allocated space.
     */
    isc_buffer_putmem(sig, gsig.value, (unsigned int)gsig.length);
    if (gsig.length != 0U)
        gss_release_buffer(&minor, &gsig);

    return (ISC_R_SUCCESS);
}

/*%
 * Verify.
 */
static isc_result_t
gssapi_verify(dst_context_t *dctx, const isc_region_t *sig) {
    dst_gssapi_signverifyctx_t *ctx = dctx->ctxdata.gssctx;
    isc_region_t message, r;
    gss_buffer_desc gmessage, gsig;
    OM_uint32 minor, gret;
    gss_ctx_id_t gssctx = dctx->key->keydata.gssctx;
    unsigned char *buf;
    char err[1024];

    /*
     * Convert the data we wish to sign into a structure gssapi can
     * understand.
     */
    isc_buffer_usedregion(ctx->buffer, &message);
    REGION_TO_GBUFFER(message, gmessage);

    /*
     * XXXMLG
     * It seem that gss_verify_mic() modifies the signature buffer,
     * at least on Heimdal's implementation.  Copy it here to an allocated
     * buffer.
     */
    buf = isc_mem_allocate(dst__memory_pool, sig->length);
    if (buf == NULL)
        return (ISC_R_FAILURE);
    memmove(buf, sig->base, sig->length);
    r.base = buf;
    r.length = sig->length;
    REGION_TO_GBUFFER(r, gsig);

    /*
     * Verify the data.
     */
    gret = gss_verify_mic(&minor, gssctx, &gmessage, &gsig, NULL);

    isc_mem_free(dst__memory_pool, buf);

    /*
     * Convert return codes into something useful to us.
     */
    if (gret != GSS_S_COMPLETE) {
        gss_log(3, "GSS verify error: %s",
            gss_error_tostring(gret, minor, err, sizeof(err)));
        if (gret == GSS_S_DEFECTIVE_TOKEN ||
            gret == GSS_S_BAD_SIG ||
            gret == GSS_S_DUPLICATE_TOKEN ||
            gret == GSS_S_OLD_TOKEN ||
            gret == GSS_S_UNSEQ_TOKEN ||
            gret == GSS_S_GAP_TOKEN ||
            gret == GSS_S_CONTEXT_EXPIRED ||
            gret == GSS_S_NO_CONTEXT ||
            gret == GSS_S_FAILURE)
            return(DST_R_VERIFYFAILURE);
        else
            return (ISC_R_FAILURE);
    }

    return (ISC_R_SUCCESS);
}

static isc_boolean_t
gssapi_compare(const dst_key_t *key1, const dst_key_t *key2) {
    gss_ctx_id_t gsskey1 = key1->keydata.gssctx;
    gss_ctx_id_t gsskey2 = key2->keydata.gssctx;

    /* No idea */
    return (ISC_TF(gsskey1 == gsskey2));
}

static isc_result_t
gssapi_generate(dst_key_t *key, int unused, void (*callback)(int)) {
    UNUSED(key);
    UNUSED(unused);
    UNUSED(callback);

    /* No idea */
    return (ISC_R_FAILURE);
}

static isc_boolean_t
gssapi_isprivate(const dst_key_t *key) {
    UNUSED(key);
    return (ISC_TRUE);
}

static void
gssapi_destroy(dst_key_t *key) {
    REQUIRE(key != NULL);
    dst_gssapi_deletectx(key->mctx, &key->keydata.gssctx);
    key->keydata.gssctx = NULL;
}

static isc_result_t
gssapi_restore(dst_key_t *key, const char *keystr) {
    OM_uint32 major, minor;
    unsigned int len;
    isc_buffer_t *b = NULL;
    isc_region_t r;
    gss_buffer_desc gssbuffer;
    isc_result_t result;

    len = strlen(keystr);
    if ((len % 4) != 0U)
        return (ISC_R_BADBASE64);

    len = (len / 4) * 3;

    result = isc_buffer_allocate(key->mctx, &b, len);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_base64_decodestring(keystr, b);
    if (result != ISC_R_SUCCESS) {
        isc_buffer_free(&b);
        return (result);
    }

    isc_buffer_remainingregion(b, &r);
    REGION_TO_GBUFFER(r, gssbuffer);
    major = gss_import_sec_context(&minor, &gssbuffer,
                       &key->keydata.gssctx);
    if (major != GSS_S_COMPLETE) {
        isc_buffer_free(&b);
        return (ISC_R_FAILURE);
    }

    isc_buffer_free(&b);
    return (ISC_R_SUCCESS);
}

static isc_result_t
gssapi_dump(dst_key_t *key, isc_mem_t *mctx, char **buffer, int *length) {
    OM_uint32 major, minor;
    gss_buffer_desc gssbuffer;
    size_t len;
    char *buf;
    isc_buffer_t b;
    isc_region_t r;
    isc_result_t result;

    major = gss_export_sec_context(&minor, &key->keydata.gssctx,
                       &gssbuffer);
    if (major != GSS_S_COMPLETE) {
        fprintf(stderr, "gss_export_sec_context -> %d, %d\n",
            major, minor);
        return (ISC_R_FAILURE);
    }
    if (gssbuffer.length == 0U)
        return (ISC_R_FAILURE);
    len = ((gssbuffer.length + 2)/3) * 4;
    buf = isc_mem_get(mctx, len);
    if (buf == NULL) {
        gss_release_buffer(&minor, &gssbuffer);
        return (ISC_R_NOMEMORY);
    }
    isc_buffer_init(&b, buf, (unsigned int)len);
    GBUFFER_TO_REGION(gssbuffer, r);
    result = isc_base64_totext(&r, 0, "", &b);
    RUNTIME_CHECK(result == ISC_R_SUCCESS);
    gss_release_buffer(&minor, &gssbuffer);
    *buffer = buf;
    *length = (int)len;
    return (ISC_R_SUCCESS);
}

static dst_func_t gssapi_functions = {
    gssapi_create_signverify_ctx,
    NULL, /*%< createctx2 */
    gssapi_destroy_signverify_ctx,
    gssapi_adddata,
    gssapi_sign,
    gssapi_verify,
    NULL, /*%< verify2 */
    NULL, /*%< computesecret */
    gssapi_compare,
    NULL, /*%< paramcompare */
    gssapi_generate,
    gssapi_isprivate,
    gssapi_destroy,
    NULL, /*%< todns */
    NULL, /*%< fromdns */
    NULL, /*%< tofile */
    NULL, /*%< parse */
    NULL, /*%< cleanup */
    NULL,  /*%< fromlabel */
    gssapi_dump,
    gssapi_restore,
};

isc_result_t
dst__gssapi_init(dst_func_t **funcp) {
    REQUIRE(funcp != NULL);
    if (*funcp == NULL)
        *funcp = &gssapi_functions;
    return (ISC_R_SUCCESS);
}

#else
int  gssapi_link_unneeded = 1;
#endif

/*! \file */