/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */

/*

 * Copyright 2010  by the Massachusetts Institute of Technology.

 * All Rights Reserved.

 *

 * Export of this software from the United States of America may

 *   require a specific license from the United States Government.

 *   It is the responsibility of any person or organization contemplating

 *   export to obtain such a license before exporting.

 *

 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and

 * distribute this software and its documentation for any purpose and

 * without fee is hereby granted, provided that the above copyright

 * notice appear in all copies and that both that copyright notice and

 * this permission notice appear in supporting documentation, and that

 * the name of M.I.T. not be used in advertising or publicity pertaining

 * to distribution of the software without specific, written prior

 * permission.  Furthermore if you modify this software you must label

 * your software as modified software and not distribute it in such a

 * fashion that it might be confused with the original M.I.T. software.

 * M.I.T. makes no representations about the suitability of

 * this software for any purpose.  It is provided "as is" without express

 * or implied warranty.

 *

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <assert.h>

#include "common.h"

static gss_OID_desc mech_krb5_wrong = {

    9, "\052\206\110\202\367\022\001\002\002"

};

gss_OID_set_desc mechset_krb5_wrong = { 1, &mech_krb5_wrong };

/*

 * Test program for SPNEGO and gss_set_neg_mechs

 *

 * Example usage:

 *

 * kinit testuser

 * ./t_spnego host/test.host@REALM testhost.keytab

 */

/* Replace *tok and *len with the concatenation of prefix and *tok. */

static void

prepend(const void *prefix, size_t plen, uint8_t **tok, size_t *len)

{

    uint8_t *newtok;

    newtok = malloc(plen + *len);

    assert(newtok != NULL);

    memcpy(newtok, prefix, plen);

    memcpy(newtok + plen, *tok, *len);

    free(*tok);

    *tok = newtok;

    *len = plen + *len;

}

/* Replace *tok and *len with *tok wrapped in a DER tag with the given tag

 * byte.  *len must be less than 2^16. */

static void

der_wrap(uint8_t tag, uint8_t **tok, size_t *len)

{

    char lenbuf[3];

    uint8_t *wrapped;

    size_t llen;

    if (*len < 128) {

        lenbuf[0] = *len;

        llen = 1;

    } else if (*len < 256) {

        lenbuf[0] = 0x81;

        lenbuf[1] = *len;

        llen = 2;

    } else {

        assert(*len >> 16 == 0);

        lenbuf[0] = 0x82;

        lenbuf[1] = *len >> 8;

        lenbuf[2] = *len & 0xFF;

        llen = 3;

    }

    wrapped = malloc(1 + llen + *len);

    assert(wrapped != NULL);

    *wrapped = tag;

    memcpy(wrapped + 1, lenbuf, llen);

    memcpy(wrapped + 1 + llen, *tok, *len);

    free(*tok);

    *tok = wrapped;

    *len = 1 + llen + *len;

}

/*

 * Create a SPNEGO initiator token for the erroneous Microsoft krb5 mech OID,

 * wrapping a krb5 token ktok.  The token should look like:

 *

 * 60 <len> (GSS framing sequence)

 *   06 06 2B 06 01 05 05 02 (SPNEGO OID)

 *   A0 <len> (NegotiationToken choice 0, negTokenInit)

 *     30 <len> (sequence)

 *       A0 0D (context tag 0, mechTypes)

 *         30 0B (sequence of)

 *           06 09 2A 86 48 82 F7 12 01 02 02 (wrong krb5 OID)

 *       A2 <len> (context tag 2, mechToken)

 *         04 <len> (octet string)

 *           <mech token octets>

 */

static void

create_mskrb5_spnego_token(gss_buffer_t ktok, gss_buffer_desc *tok_out)

{

    uint8_t *tok;

    size_t len;

    len = ktok->length;

    tok = malloc(len);

    assert(tok != NULL);

    memcpy(tok, ktok->value, len);

    /* Wrap the krb5 token in OCTET STRING and [2] tags. */

    der_wrap(0x04, &tok, &len;;

    der_wrap(0xA2, &tok, &len;;

    /* Prepend the wrong krb5 OID inside OBJECT IDENTIFIER and [0] tags. */

    prepend("\xA0\x0D\x30\x0B\x06\x09\x2A\x86\x48\x82\xF7\x12\x01\x02\x02", 15,

            &tok, &len;;

    /* Wrap the previous two things in SEQUENCE and [0] tags. */

    der_wrap(0x30, &tok, &len;;

    der_wrap(0xA0, &tok, &len;;

    /* Prepend the SPNEGO OID in an OBJECT IDENTIFIER tag. */

    prepend("\x06\x06\x2B\x06\x01\x05\x05\x02", 8, &tok, &len;;

    /* Wrap the whole thing in an [APPLICATION 0] tag. */

    der_wrap(0x60, &tok, &len;;

    tok_out->value = tok;

    tok_out->length = len;

}

/*

 * Test that the SPNEGO acceptor code accepts and properly reflects back the

 * erroneous Microsoft mech OID in the supportedMech field of the NegTokenResp

 * message.  Use acred as the verifier cred handle.

 */

static void

test_mskrb_oid(gss_name_t tname, gss_cred_id_t acred)

{

    OM_uint32 major, minor;

    gss_ctx_id_t ictx = GSS_C_NO_CONTEXT, actx = GSS_C_NO_CONTEXT;

    gss_buffer_desc atok = GSS_C_EMPTY_BUFFER, ktok = GSS_C_EMPTY_BUFFER, stok;

    const unsigned char *atok_oid;

    /*

     * Our SPNEGO mech no longer acquires creds for the wrong mech OID, so we

     * have to construct a SPNEGO token ourselves.

     */

    major = gss_init_sec_context(&minor, GSS_C_NO_CREDENTIAL, &ictx, tname,

                                 &mech_krb5, 0, GSS_C_INDEFINITE,

                                 GSS_C_NO_CHANNEL_BINDINGS, &atok, NULL, &ktok,

                                 NULL, NULL);

    check_gsserr("gss_init_sec_context(mskrb)", major, minor);

    assert(major == GSS_S_COMPLETE);

    create_mskrb5_spnego_token(&ktok, &stok);

    /*

     * Look directly at the DER encoding of the response token.  Since we

     * didn't request mutual authentication, the SPNEGO reply will contain no

     * underlying mech token; therefore, the encoding of the correct

     * NegotiationToken response is completely predictable:

     *

     *   A1 14 (choice 1, length 20, meaning negTokenResp)

     *     30 12 (sequence, length 18)

     *       A0 03 (context tag 0, length 3)

     *         0A 01 00 (enumerated value 0, meaning accept-completed)

     *       A1 0B (context tag 1, length 11)

     *         06 09 (object identifier, length 9)

     *           2A 86 48 82 F7 12 01 02 02 (the erroneous krb5 OID)

     *

     * So we can just compare the length to 22 and the nine bytes at offset 13

     * to the expected OID.

     */

    major = gss_accept_sec_context(&minor, &actx, acred, &stok,

                                   GSS_C_NO_CHANNEL_BINDINGS, NULL,

                                   NULL, &atok, NULL, NULL, NULL);

    check_gsserr("gss_accept_sec_context(mskrb)", major, minor);

    assert(atok.length == 22);

    atok_oid = (unsigned char *)atok.value + 13;

    assert(memcmp(atok_oid, mech_krb5_wrong.elements, 9) == 0);

    (void)gss_delete_sec_context(&minor, &ictx, NULL);

    (void)gss_delete_sec_context(&minor, &actx, NULL);

    (void)gss_release_buffer(&minor, &ktok);

    (void)gss_release_buffer(&minor, &atok);

    free(stok.value);

}

/* Check that we return a compatibility NegTokenInit2 message containing

 * NegHints for an empty initiator token. */

static void

test_neghints()

{

    OM_uint32 major, minor;

    gss_buffer_desc itok = GSS_C_EMPTY_BUFFER, atok;

    gss_ctx_id_t actx = GSS_C_NO_CONTEXT;

    const char *expected =

        /* RFC 2743 token framing: [APPLICATION 0] IMPLICIT SEQUENCE followed

         * by OBJECT IDENTIFIER and the SPNEGO OID */

        "\x60\x47\x06\x06" "\x2B\x06\x01\x05\x05\x02"

        /* [0] SEQUENCE for the NegotiationToken negtokenInit choice */

        "\xA0\x3D\x30\x3B"

        /* [0] MechTypeList containing the krb5 OID */

        "\xA0\x0D\x30\x0B\x06\x09" "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"

        /* [3] NegHints containing [0] GeneralString containing the dummy

         * hintName string defined in [MS-SPNG] */

        "\xA3\x2A\x30\x28\xA0\x26\x1B\x24"

        "not_defined_in_RFC4178@please_ignore";

    /* Produce a hint token. */

    major = gss_accept_sec_context(&minor, &actx, GSS_C_NO_CREDENTIAL, &itok,

                                   GSS_C_NO_CHANNEL_BINDINGS, NULL, NULL,

                                   &atok, NULL, NULL, NULL);

    check_gsserr("gss_accept_sec_context(neghints)", major, minor);

    /* Verify it against the expected contents, which are fixed as long as we

     * only list the krb5 mech in the token. */

    assert(atok.length == strlen(expected));

    assert(memcmp(atok.value, expected, atok.length) == 0);

    (void)gss_release_buffer(&minor, &atok);

    (void)gss_delete_sec_context(&minor, &actx, NULL);

}

int

main(int argc, char *argv[])

{

    OM_uint32 minor, major, flags;

    gss_cred_id_t verifier_cred_handle = GSS_C_NO_CREDENTIAL;

    gss_cred_id_t initiator_cred_handle = GSS_C_NO_CREDENTIAL;

    gss_OID_set actual_mechs = GSS_C_NO_OID_SET;

    gss_ctx_id_t initiator_context, acceptor_context;

    gss_name_t target_name, source_name = GSS_C_NO_NAME;

    gss_OID mech = GSS_C_NO_OID;

    gss_OID_desc pref_oids[2];

    gss_OID_set_desc pref_mechs;

    if (argc < 2 || argc > 3) {

        fprintf(stderr, "Usage: %s target_name [keytab]\n", argv[0]);

        exit(1);

    }

    target_name = import_name(argv[1]);

    if (argc >= 3) {

        major = krb5_gss_register_acceptor_identity(argv[2]);

        check_gsserr("krb5_gss_register_acceptor_identity", major, 0);

    }

    /* Get default initiator cred. */

    major = gss_acquire_cred(&minor, GSS_C_NO_NAME, GSS_C_INDEFINITE,

                             &mechset_spnego, GSS_C_INITIATE,

                             &initiator_cred_handle, NULL, NULL);

    check_gsserr("gss_acquire_cred(initiator)", major, minor);

    /*

     * The following test is designed to exercise SPNEGO reselection on the

     * client and server.  Unfortunately, it no longer does so after tickets

     * #8217 and #8021, since SPNEGO now only acquires a single krb5 cred and

     * there is no way to expand the underlying creds with gss_set_neg_mechs().

     * To fix this we need gss_acquire_cred_with_cred() or some other way to

     * turn a cred with a specifically requested mech set into a SPNEGO cred.

     */

    /* Make the initiator prefer IAKERB and offer krb5 as an alternative. */

    pref_oids[0] = mech_iakerb;

    pref_oids[1] = mech_krb5;

    pref_mechs.count = 2;

    pref_mechs.elements = pref_oids;

    major = gss_set_neg_mechs(&minor, initiator_cred_handle, &pref_mechs);

    check_gsserr("gss_set_neg_mechs(initiator)", major, minor);

    /* Get default acceptor cred. */

    major = gss_acquire_cred(&minor, GSS_C_NO_NAME, GSS_C_INDEFINITE,

                             &mechset_spnego, GSS_C_ACCEPT,

                             &verifier_cred_handle, &actual_mechs, NULL);

    check_gsserr("gss_acquire_cred(acceptor)", major, minor);

    /* Restrict the acceptor to krb5 (which will force a reselection). */

    major = gss_set_neg_mechs(&minor, verifier_cred_handle, &mechset_krb5);

    check_gsserr("gss_set_neg_mechs(acceptor)", major, minor);

    flags = GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG;

    establish_contexts(&mech_spnego, initiator_cred_handle,

                       verifier_cred_handle, target_name, flags,

                       &initiator_context, &acceptor_context, &source_name,

                       &mech, NULL);

    display_canon_name("Source name", source_name, &mech_krb5);

    display_oid("Source mech", mech);

    /* Test acceptance of the erroneous Microsoft krb5 OID, with and without an

     * acceptor cred. */

    test_mskrb_oid(target_name, verifier_cred_handle);

    test_mskrb_oid(target_name, GSS_C_NO_CREDENTIAL);

    test_neghints();

    (void)gss_delete_sec_context(&minor, &initiator_context, NULL);

    (void)gss_delete_sec_context(&minor, &acceptor_context, NULL);

    (void)gss_release_name(&minor, &source_name);

    (void)gss_release_name(&minor, &target_name);

    (void)gss_release_cred(&minor, &initiator_cred_handle);

    (void)gss_release_cred(&minor, &verifier_cred_handle);

    (void)gss_release_oid_set(&minor, &actual_mechs);

    return 0;

}