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
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
|
/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* kdc/ndr.c - NDR encoding and decoding functions */
/*
* Copyright (C) 2021 by Red Hat, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "k5-int.h"
#include "k5-input.h"
#include "k5-buf.h"
#include "k5-utf8.h"
#include "kdc_util.h"
struct encoded_wchars {
uint16_t bytes_len;
uint16_t num_wchars;
uint8_t *encoded;
};
/*
* MS-DTYP 2.3.10:
*
* typedef struct _RPC_UNICODE_STRING {
* unsigned short Length;
* unsigned short MaximumLength;
* [size_is(MaximumLength/2), length_is(Length/2)] WCHAR* Buffer;
* } RPC_UNICODE_STRING, *PRPC_UNICODE_STRING;
*
* Note that Buffer is not a String - there's no termination.
*
* We don't actually decode Length and MaximumLength here - this is a
* conformant-varying array, which means that (per DCE-1.1-RPC 14.3.7.2) where
* those actually appear in the serialized data is variable depending on
* whether the string is at top level of the struct or not. (This also
* affects where the pointer identifier appears.)
*
* See MS-RPCE 4.7 for what an RPC_UNICODE_STRING looks like when not at
* top-level.
*/
static krb5_error_code
dec_wchar_pointer(struct k5input *in, char **out)
{
const uint8_t *bytes;
uint32_t actual_count;
/* Maximum count. */
(void)k5_input_get_uint32_le(in);
/* Offset - all zeroes, "should" not be checked. */
(void)k5_input_get_uint32_le(in);
actual_count = k5_input_get_uint32_le(in);
if (actual_count > UINT32_MAX / 2)
return ERANGE;
bytes = k5_input_get_bytes(in, actual_count * 2);
if (bytes == NULL || k5_utf16le_to_utf8(bytes, actual_count * 2, out) != 0)
return EINVAL;
/* Always align on 4. */
if (actual_count % 2 == 1)
(void)k5_input_get_uint16_le(in);
return 0;
}
static krb5_error_code
enc_wchar_pointer(const char *utf8, struct encoded_wchars *encoded_out)
{
krb5_error_code ret;
struct k5buf b;
size_t utf16len, num_wchars;
uint8_t *utf16;
k5_buf_init_dynamic(&b);
ret = k5_utf8_to_utf16le(utf8, &utf16, &utf16len);
if (ret)
return ret;
num_wchars = utf16len / 2;
k5_buf_add_uint32_le(&b, num_wchars + 1);
k5_buf_add_uint32_le(&b, 0);
k5_buf_add_uint32_le(&b, num_wchars);
k5_buf_add_len(&b, utf16, utf16len);
free(utf16);
if (num_wchars % 2 == 1)
k5_buf_add_uint16_le(&b, 0);
ret = k5_buf_status(&b);
if (ret)
return ret;
encoded_out->bytes_len = b.len;
encoded_out->num_wchars = num_wchars;
encoded_out->encoded = b.data;
return 0;
}
/*
* Decode a delegation info structure, leaving room to add an additional
* service.
*
* MS-PAC 2.9:
*
* typedef struct _S4U_DELEGATION_INFO {
* RPC_UNICODE_STRING S4U2proxyTarget;
* ULONG TransitedListSize;
* [size_is(TransitedListSize)] PRPC_UNICODE_STRING S4UTransitedServices;
* } S4U_DELEGATION_INFO, *PS4U_DELEGATION_INFO;
*/
krb5_error_code
ndr_dec_delegation_info(krb5_data *data, struct pac_s4u_delegation_info **out)
{
krb5_error_code ret;
struct pac_s4u_delegation_info *di = NULL;
struct k5input in;
uint32_t i, object_buffer_length, nservices;
uint8_t version, endianness, common_header_length;
*out = NULL;
di = k5alloc(sizeof(*di), &ret);
if (di == NULL)
return ret;
k5_input_init(&in, data->data, data->length);
/* Common Type Header - MS-RPCE 2.2.6.1 */
version = k5_input_get_byte(&in);
endianness = k5_input_get_byte(&in);
common_header_length = k5_input_get_uint16_le(&in);
(void)k5_input_get_uint32_le(&in); /* Filler - 0xcccccccc. */
if (version != 1 || endianness != 0x10 || common_header_length != 8) {
ret = EINVAL;
goto error;
}
/* Private Header for Constructed Type - MS-RPCE 2.2.6.2 */
object_buffer_length = k5_input_get_uint32_le(&in);
if (data->length < 16 || object_buffer_length != data->length - 16) {
ret = EINVAL;
goto error;
}
(void)k5_input_get_uint32_le(&in); /* Filler - 0. */
/* This code doesn't handle re-used pointers, which could come into play in
* the unlikely case of a delegation loop. */
/* Pointer. Microsoft always starts at 00 00 02 00 */
(void)k5_input_get_uint32_le(&in);
/* Length of proxy target - 2 */
(void)k5_input_get_uint16_le(&in);
/* Length of proxy target */
(void)k5_input_get_uint16_le(&in);
/* Another pointer - 04 00 02 00. Microsoft increments by 4 (le). */
(void)k5_input_get_uint32_le(&in);
/* Transited services length - header version. */
(void)k5_input_get_uint32_le(&in);
/* More pointer: 08 00 02 00 */
(void)k5_input_get_uint32_le(&in);
ret = dec_wchar_pointer(&in, &di->proxy_target);
if (ret)
goto error;
nservices = k5_input_get_uint32_le(&in);
/* Here, we have encoded 2 bytes of length, 2 bytes of (length + 2), and 4
* bytes of pointer, for each element (deferred pointers). */
if (nservices > data->length / 8) {
ret = ERANGE;
goto error;
}
(void)k5_input_get_bytes(&in, 8 * nservices);
/* Since we're likely to add another entry, leave a blank at the end. */
di->transited_services = k5calloc(nservices + 1, sizeof(char *), &ret);
if (di->transited_services == NULL)
goto error;
for (i = 0; i < nservices; i++) {
ret = dec_wchar_pointer(&in, &di->transited_services[i]);
if (ret)
goto error;
di->transited_services_length++;
}
ret = in.status;
if (ret)
goto error;
*out = di;
return 0;
error:
ndr_free_delegation_info(di);
return ret;
}
/* Empirically, Microsoft starts pointers at 00 00 02 00, and if treated little
* endian, they increase by 4. */
static inline void
write_ptr(struct k5buf *buf, uint32_t *pointer)
{
if (*pointer == 0)
*pointer = 0x00020000;
k5_buf_add_uint32_le(buf, *pointer);
*pointer += 4;
}
krb5_error_code
ndr_enc_delegation_info(struct pac_s4u_delegation_info *in, krb5_data *out)
{
krb5_error_code ret;
size_t i;
struct k5buf b;
struct encoded_wchars pt_encoded = { 0 }, *tss_encoded = NULL;
uint32_t pointer = 0;
/* Encode ahead of time since we need the lengths. */
ret = enc_wchar_pointer(in->proxy_target, &pt_encoded);
if (ret)
goto cleanup;
tss_encoded = k5calloc(in->transited_services_length, sizeof(*tss_encoded),
&ret);
if (tss_encoded == NULL)
goto cleanup;
k5_buf_init_dynamic(&b);
/* Common Type Header - MS-RPCE 2.2.6.1 */
k5_buf_add_len(&b, "\x01\x10\x08\x00", 4);
k5_buf_add_uint32_le(&b, 0xcccccccc);
/* Private Header for Constructed Type - MS-RPCE 2.2.6.2 */
k5_buf_add_uint32_le(&b, 0); /* Skip over where payload length goes. */
k5_buf_add_uint32_le(&b, 0); /* Filler - all zeroes. */
write_ptr(&b, &pointer);
k5_buf_add_uint16_le(&b, 2 * pt_encoded.num_wchars);
k5_buf_add_uint16_le(&b, 2 * (pt_encoded.num_wchars + 1));
write_ptr(&b, &pointer);
k5_buf_add_uint32_le(&b, in->transited_services_length);
write_ptr(&b, &pointer);
k5_buf_add_len(&b, pt_encoded.encoded, pt_encoded.bytes_len);
k5_buf_add_uint32_le(&b, in->transited_services_length);
/* Deferred pointers. */
for (i = 0; i < in->transited_services_length; i++) {
ret = enc_wchar_pointer(in->transited_services[i], &tss_encoded[i]);
if (ret)
goto cleanup;
k5_buf_add_uint16_le(&b, 2 * tss_encoded[i].num_wchars);
k5_buf_add_uint16_le(&b, 2 * (tss_encoded[i].num_wchars + 1));
write_ptr(&b, &pointer);
}
for (i = 0; i < in->transited_services_length; i++)
k5_buf_add_len(&b, tss_encoded[i].encoded, tss_encoded[i].bytes_len);
/* Now, pad to 8 bytes. RPC_UNICODE_STRING is aligned on 4 bytes. */
if (b.len % 8 != 0)
k5_buf_add_uint32_le(&b, 0);
/* Record the payload length where we skipped over it previously. */
if (b.data != NULL)
store_32_le(b.len - 0x10, ((uint8_t *)b.data) + 8);
ret = k5_buf_status(&b);
if (ret)
goto cleanup;
*out = make_data(b.data, b.len);
b.data = NULL;
cleanup:
free(b.data);
free(pt_encoded.encoded);
for (i = 0; tss_encoded != NULL && i < in->transited_services_length; i++)
free(tss_encoded[i].encoded);
free(tss_encoded);
return ret;
}
void
ndr_free_delegation_info(struct pac_s4u_delegation_info *di)
{
uint32_t i;
if (di == NULL)
return;
free(di->proxy_target);
for (i = 0; i < di->transited_services_length; i++)
free(di->transited_services[i]);
free(di->transited_services);
free(di);
}
|