aboutsummaryrefslogtreecommitdiffstats
path: root/src/lib/krb5/krb/send_tgs.c
blob: e43a5cc5b135349e5ed4f91cf80149eff0b4ba5a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/krb5/krb/send_tgs.c - Construct a TGS request */
/*
 * Copyright 1990,1991,2009,2013 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 "k5-int.h"
#include "int-proto.h"
#include "fast.h"

/* Choose a random nonce for an AS or TGS request. */
krb5_error_code
k5_generate_nonce(krb5_context context, int32_t *out)
{
    krb5_error_code ret;
    unsigned char random_buf[4];
    krb5_data random_data = make_data(random_buf, 4);

    *out = 0;

    /* We and Heimdal incorrectly encode nonces as signed, so make sure we use
     * a non-negative value to avoid interoperability issues. */
    ret = krb5_c_random_make_octets(context, &random_data);
    if (ret)
        return ret;
    *out = 0x7FFFFFFF & load_32_n(random_buf);
    return 0;
}

/* Construct an AP-REQ message for a TGS request. */
static krb5_error_code
tgs_construct_ap_req(krb5_context context, krb5_data *checksum_data,
                     krb5_creds *tgt, krb5_keyblock *subkey,
                     krb5_data **ap_req_asn1_out)
{
    krb5_cksumtype cksumtype;
    krb5_error_code ret;
    krb5_checksum checksum;
    krb5_authenticator authent;
    krb5_ap_req ap_req;
    krb5_data *authent_asn1 = NULL;
    krb5_ticket *ticket = NULL;
    krb5_enc_data authent_enc;

    *ap_req_asn1_out = NULL;
    memset(&checksum, 0, sizeof(checksum));
    memset(&ap_req, 0, sizeof(ap_req));
    memset(&authent_enc, 0, sizeof(authent_enc));

    /* Determine the authenticator checksum type. */
    switch (tgt->keyblock.enctype) {
    case ENCTYPE_DES_CBC_CRC:
    case ENCTYPE_DES_CBC_MD4:
    case ENCTYPE_DES_CBC_MD5:
    case ENCTYPE_ARCFOUR_HMAC:
    case ENCTYPE_ARCFOUR_HMAC_EXP:
        cksumtype = context->kdc_req_sumtype;
        break;
    default:
        ret = krb5int_c_mandatory_cksumtype(context, tgt->keyblock.enctype,
                                            &cksumtype);
        if (ret)
            goto cleanup;
    }

    /* Generate checksum. */
    ret = krb5_c_make_checksum(context, cksumtype, &tgt->keyblock,
                               KRB5_KEYUSAGE_TGS_REQ_AUTH_CKSUM, checksum_data,
                               &checksum);
    if (ret)
        goto cleanup;

    /* Construct, encode, and encrypt an authenticator. */
    authent.subkey = subkey;
    authent.seq_number = 0;
    authent.checksum = &checksum;
    authent.client = tgt->client;
    authent.authorization_data = tgt->authdata;
    ret = krb5_us_timeofday(context, &authent.ctime, &authent.cusec);
    if (ret)
        goto cleanup;
    ret = encode_krb5_authenticator(&authent, &authent_asn1);
    if (ret)
        goto cleanup;
    ret = krb5_encrypt_helper(context, &tgt->keyblock,
                              KRB5_KEYUSAGE_TGS_REQ_AUTH, authent_asn1,
                              &authent_enc);
    if (ret)
        goto cleanup;

    ret = decode_krb5_ticket(&tgt->ticket, &ticket);
    if (ret)
        goto cleanup;

    /* Encode the AP-REQ. */
    ap_req.authenticator = authent_enc;
    ap_req.ticket = ticket;
    ret = encode_krb5_ap_req(&ap_req, ap_req_asn1_out);

cleanup:
    free(checksum.contents);
    krb5_free_ticket(context, ticket);
    krb5_free_data_contents(context, &authent_enc.ciphertext);
    if (authent_asn1 != NULL)
        zapfree(authent_asn1->data, authent_asn1->length);
    free(authent_asn1);
    return ret;
}

/*
 * Construct a TGS request and return its ASN.1 encoding as well as the
 * timestamp, nonce, and subkey used.  The pacb_fn callback allows the caller
 * to amend the request padata after the nonce and subkey are determined.
 */
krb5_error_code
k5_make_tgs_req(krb5_context context,
                struct krb5int_fast_request_state *fast_state,
                krb5_creds *tgt, krb5_flags kdcoptions,
                krb5_address *const *addrs, krb5_pa_data **in_padata,
                krb5_creds *desired, k5_pacb_fn pacb_fn, void *pacb_data,
                krb5_data *req_asn1_out, krb5_timestamp *timestamp_out,
                krb5_int32 *nonce_out, krb5_keyblock **subkey_out)
{
    krb5_error_code ret;
    krb5_kdc_req req;
    krb5_data *authdata_asn1 = NULL, *req_body_asn1 = NULL;
    krb5_data *ap_req_asn1 = NULL, *tgs_req_asn1 = NULL;
    krb5_ticket *sec_ticket = NULL;
    krb5_ticket *sec_ticket_arr[2];
    krb5_timestamp time_now;
    krb5_pa_data **padata = NULL, *pa;
    krb5_keyblock *subkey = NULL;
    krb5_enc_data authdata_enc;
    krb5_enctype enctypes[2], *defenctypes = NULL;
    size_t count, i;

    *req_asn1_out = empty_data();
    *timestamp_out = 0;
    *nonce_out = 0;
    *subkey_out = NULL;
    memset(&req, 0, sizeof(req));
    memset(&authdata_enc, 0, sizeof(authdata_enc));

    /* tgt's client principal must match the desired client principal. */
    if (!krb5_principal_compare(context, tgt->client, desired->client))
        return KRB5_PRINC_NOMATCH;

    /* tgt must be an actual credential, not a template. */
    if (!tgt->ticket.length)
        return KRB5_NO_TKT_SUPPLIED;

    req.kdc_options = kdcoptions;
    req.server = desired->server;
    req.from = desired->times.starttime;
    req.till = desired->times.endtime ? desired->times.endtime :
        tgt->times.endtime;
    req.rtime = desired->times.renew_till;
    ret = k5_generate_nonce(context, &req.nonce);
    if (ret)
        return ret;
    *nonce_out = req.nonce;
    ret = krb5_timeofday(context, &time_now);
    if (ret)
        return ret;
    *timestamp_out = time_now;

    req.addresses = (krb5_address **)addrs;

    /* Generate subkey. */
    ret = krb5_generate_subkey(context, &tgt->keyblock, &subkey);
    if (ret)
        return ret;
    TRACE_SEND_TGS_SUBKEY(context, subkey);

    ret = krb5int_fast_tgs_armor(context, fast_state, subkey, &tgt->keyblock,
                                 NULL, NULL);
    if (ret)
        goto cleanup;

    if (desired->authdata != NULL) {
        ret = encode_krb5_authdata(desired->authdata, &authdata_asn1);
        if (ret)
            goto cleanup;
        ret = krb5_encrypt_helper(context, subkey,
                                  KRB5_KEYUSAGE_TGS_REQ_AD_SUBKEY,
                                  authdata_asn1, &authdata_enc);
        if (ret)
            goto cleanup;
        req.authorization_data = authdata_enc;
    }

    if (desired->keyblock.enctype != ENCTYPE_NULL) {
        if (!krb5_c_valid_enctype(desired->keyblock.enctype)) {
            ret = KRB5_PROG_ETYPE_NOSUPP;
            goto cleanup;
        }
        enctypes[0] = desired->keyblock.enctype;
        enctypes[1] = ENCTYPE_NULL;
        req.ktype = enctypes;
        req.nktypes = 1;
    } else {
        /* Get the default TGS enctypes. */
        ret = krb5_get_tgs_ktypes(context, desired->server, &defenctypes);
        if (ret)
            goto cleanup;
        for (count = 0; defenctypes[count]; count++);
        req.ktype = defenctypes;
        req.nktypes = count;
    }
    TRACE_SEND_TGS_ETYPES(context, req.ktype);

    if (kdcoptions & (KDC_OPT_ENC_TKT_IN_SKEY | KDC_OPT_CNAME_IN_ADDL_TKT)) {
        if (desired->second_ticket.length == 0) {
            ret = KRB5_NO_2ND_TKT;
            goto cleanup;
        }
        ret = decode_krb5_ticket(&desired->second_ticket, &sec_ticket);
        if (ret)
            goto cleanup;
        sec_ticket_arr[0] = sec_ticket;
        sec_ticket_arr[1] = NULL;
        req.second_ticket = sec_ticket_arr;
    }

    /* Encode the request body. */
    ret = krb5int_fast_prep_req_body(context, fast_state, &req,
                                     &req_body_asn1);
    if (ret)
        goto cleanup;

    ret = tgs_construct_ap_req(context, req_body_asn1, tgt, subkey,
                               &ap_req_asn1);
    if (ret)
        goto cleanup;

    for (count = 0; in_padata != NULL && in_padata[count] != NULL; count++);

    /* Construct a padata array for the request, beginning with the ap-req. */
    padata = k5calloc(count + 2, sizeof(krb5_pa_data *), &ret);
    if (padata == NULL)
        goto cleanup;
    padata[0] = k5alloc(sizeof(krb5_pa_data), &ret);
    if (padata[0] == NULL)
        goto cleanup;
    padata[0]->pa_type = KRB5_PADATA_AP_REQ;
    padata[0]->contents = k5memdup(ap_req_asn1->data, ap_req_asn1->length,
                                   &ret);
    if (padata[0] == NULL)
        goto cleanup;
    padata[0]->length = ap_req_asn1->length;

    /* Append copies of any other supplied padata. */
    for (i = 0; in_padata != NULL && in_padata[i] != NULL; i++) {
        pa = k5alloc(sizeof(krb5_pa_data), &ret);
        if (pa == NULL)
            goto cleanup;
        pa->pa_type = in_padata[i]->pa_type;
        pa->length = in_padata[i]->length;
        pa->contents = k5memdup(in_padata[i]->contents, in_padata[i]->length,
                                &ret);
        if (pa->contents == NULL)
            goto cleanup;
        padata[i + 1] = pa;
    }
    req.padata = padata;

    if (pacb_fn != NULL) {
        ret = (*pacb_fn)(context, subkey, &req, pacb_data);
        if (ret)
            goto cleanup;
    }

    /* Encode the TGS-REQ.  Discard the krb5_data container. */
    ret = krb5int_fast_prep_req(context, fast_state, &req, ap_req_asn1,
                                encode_krb5_tgs_req, &tgs_req_asn1);
    if (ret)
        goto cleanup;
    *req_asn1_out = *tgs_req_asn1;
    free(tgs_req_asn1);
    tgs_req_asn1 = NULL;

    *subkey_out = subkey;
    subkey = NULL;

cleanup:
    krb5_free_data(context, authdata_asn1);
    krb5_free_data(context, req_body_asn1);
    krb5_free_data(context, ap_req_asn1);
    krb5_free_pa_data(context, req.padata);
    krb5_free_ticket(context, sec_ticket);
    krb5_free_data_contents(context, &authdata_enc.ciphertext);
    krb5_free_keyblock(context, subkey);
    free(defenctypes);
    return ret;
}