1/*
2 * Copyright (c) 2006 Kungliga Tekniska Högskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "ntlm.h"
35
36uint32_t
37_krb5_crc_update (const char *p, size_t len, uint32_t res);
38void
39_krb5_crc_init_table(void);
40
41/*
42 *
43 */
44
45static void
46encode_le_uint32(uint32_t n, unsigned char *p)
47{
48  p[0] = (n >> 0)  & 0xFF;
49  p[1] = (n >> 8)  & 0xFF;
50  p[2] = (n >> 16) & 0xFF;
51  p[3] = (n >> 24) & 0xFF;
52}
53
54
55static void
56decode_le_uint32(const void *ptr, uint32_t *n)
57{
58    const unsigned char *p = ptr;
59    *n = (p[0] << 0) | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
60}
61
62/*
63 *
64 */
65
66const char a2i_signmagic[] =
67    "session key to server-to-client signing key magic constant";
68const char a2i_sealmagic[] =
69    "session key to server-to-client sealing key magic constant";
70const char i2a_signmagic[] =
71    "session key to client-to-server signing key magic constant";
72const char i2a_sealmagic[] =
73    "session key to client-to-server sealing key magic constant";
74
75
76void
77_gss_ntlm_set_key(struct ntlmv2_key *key, int acceptor, int sealsign,
78		  unsigned char *data, size_t len)
79{
80    unsigned char out[16];
81    EVP_MD_CTX *ctx;
82    const char *signmagic;
83    const char *sealmagic;
84
85    if (acceptor) {
86	signmagic = a2i_signmagic;
87	sealmagic = a2i_sealmagic;
88    } else {
89	signmagic = i2a_signmagic;
90	sealmagic = i2a_sealmagic;
91    }
92
93    key->seq = 0;
94
95    ctx = EVP_MD_CTX_create();
96    EVP_DigestInit_ex(ctx, EVP_md5(), NULL);
97    EVP_DigestUpdate(ctx, data, len);
98    EVP_DigestUpdate(ctx, signmagic, strlen(signmagic) + 1);
99    EVP_DigestFinal_ex(ctx, key->signkey, NULL);
100
101    EVP_DigestInit_ex(ctx, EVP_md5(), NULL);
102    EVP_DigestUpdate(ctx, data, len);
103    EVP_DigestUpdate(ctx, sealmagic, strlen(sealmagic) + 1);
104    EVP_DigestFinal_ex(ctx, out, NULL);
105    EVP_MD_CTX_destroy(ctx);
106
107    RC4_set_key(&key->sealkey, 16, out);
108    if (sealsign)
109	key->signsealkey = &key->sealkey;
110}
111
112/*
113 *
114 */
115
116static OM_uint32
117v1_sign_message(gss_buffer_t in,
118		RC4_KEY *signkey,
119		uint32_t seq,
120		unsigned char out[16])
121{
122    unsigned char sigature[12];
123    uint32_t crc;
124
125    _krb5_crc_init_table();
126    crc = _krb5_crc_update(in->value, in->length, 0);
127
128    encode_le_uint32(0, &sigature[0]);
129    encode_le_uint32(crc, &sigature[4]);
130    encode_le_uint32(seq, &sigature[8]);
131
132    encode_le_uint32(1, out); /* version */
133    RC4(signkey, sizeof(sigature), sigature, out + 4);
134
135    if (RAND_bytes(out + 4, 4) != 1)
136	return GSS_S_UNAVAILABLE;
137
138    return 0;
139}
140
141
142static OM_uint32
143v2_sign_message(gss_buffer_t in,
144		unsigned char signkey[16],
145		RC4_KEY *sealkey,
146		uint32_t seq,
147		unsigned char out[16])
148{
149    unsigned char hmac[16];
150    unsigned int hmaclen;
151    HMAC_CTX c;
152
153    HMAC_CTX_init(&c);
154    HMAC_Init_ex(&c, signkey, 16, EVP_md5(), NULL);
155
156    encode_le_uint32(seq, hmac);
157    HMAC_Update(&c, hmac, 4);
158    HMAC_Update(&c, in->value, in->length);
159    HMAC_Final(&c, hmac, &hmaclen);
160    HMAC_CTX_cleanup(&c);
161
162    encode_le_uint32(1, &out[0]);
163    if (sealkey)
164	RC4(sealkey, 8, hmac, &out[4]);
165    else
166	memcpy(&out[4], hmac, 8);
167
168    memset(&out[12], 0, 4);
169
170    return GSS_S_COMPLETE;
171}
172
173static OM_uint32
174v2_verify_message(gss_buffer_t in,
175		  unsigned char signkey[16],
176		  RC4_KEY *sealkey,
177		  uint32_t seq,
178		  const unsigned char checksum[16])
179{
180    OM_uint32 ret;
181    unsigned char out[16];
182
183    ret = v2_sign_message(in, signkey, sealkey, seq, out);
184    if (ret)
185	return ret;
186
187    if (memcmp(checksum, out, 16) != 0)
188	return GSS_S_BAD_MIC;
189
190    return GSS_S_COMPLETE;
191}
192
193static OM_uint32
194v2_seal_message(const gss_buffer_t in,
195		unsigned char signkey[16],
196		uint32_t seq,
197		RC4_KEY *sealkey,
198		gss_buffer_t out)
199{
200    unsigned char *p;
201    OM_uint32 ret;
202
203    if (in->length + 16 < in->length)
204	return EINVAL;
205
206    p = malloc(in->length + 16);
207    if (p == NULL)
208	return ENOMEM;
209
210    RC4(sealkey, in->length, in->value, p);
211
212    ret = v2_sign_message(in, signkey, sealkey, seq, &p[in->length]);
213    if (ret) {
214	free(p);
215	return ret;
216    }
217
218    out->value = p;
219    out->length = in->length + 16;
220
221    return 0;
222}
223
224static OM_uint32
225v2_unseal_message(gss_buffer_t in,
226		  unsigned char signkey[16],
227		  uint32_t seq,
228		  RC4_KEY *sealkey,
229		  gss_buffer_t out)
230{
231    OM_uint32 ret;
232
233    if (in->length < 16)
234	return GSS_S_BAD_MIC;
235
236    out->length = in->length - 16;
237    out->value = malloc(out->length);
238    if (out->value == NULL)
239	return GSS_S_BAD_MIC;
240
241    RC4(sealkey, out->length, in->value, out->value);
242
243    ret = v2_verify_message(out, signkey, sealkey, seq,
244			    ((const unsigned char *)in->value) + out->length);
245    if (ret) {
246	OM_uint32 junk;
247	gss_release_buffer(&junk, out);
248    }
249    return ret;
250}
251
252/*
253 *
254 */
255
256#define CTX_FLAGS_ISSET(_ctx,_flags) \
257    (((_ctx)->flags & (_flags)) == (_flags))
258
259/*
260 *
261 */
262
263OM_uint32 GSSAPI_CALLCONV
264_gss_ntlm_get_mic
265           (OM_uint32 * minor_status,
266            const gss_ctx_id_t context_handle,
267            gss_qop_t qop_req,
268            const gss_buffer_t message_buffer,
269            gss_buffer_t message_token
270           )
271{
272    ntlm_ctx ctx = (ntlm_ctx)context_handle;
273    OM_uint32 junk;
274
275    *minor_status = 0;
276
277    message_token->value = malloc(16);
278    message_token->length = 16;
279    if (message_token->value == NULL) {
280	*minor_status = ENOMEM;
281	return GSS_S_FAILURE;
282    }
283
284    if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SIGN|NTLM_NEG_NTLM2_SESSION)) {
285	OM_uint32 ret;
286
287	if ((ctx->status & STATUS_SESSIONKEY) == 0) {
288	    gss_release_buffer(&junk, message_token);
289	    return GSS_S_UNAVAILABLE;
290	}
291
292	ret = v2_sign_message(message_buffer,
293			      ctx->u.v2.send.signkey,
294			      ctx->u.v2.send.signsealkey,
295			      ctx->u.v2.send.seq++,
296			      message_token->value);
297	if (ret)
298	    gss_release_buffer(&junk, message_token);
299        return ret;
300
301    } else if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SIGN)) {
302	OM_uint32 ret;
303
304	if ((ctx->status & STATUS_SESSIONKEY) == 0) {
305	    gss_release_buffer(&junk, message_token);
306	    return GSS_S_UNAVAILABLE;
307	}
308
309	ret = v1_sign_message(message_buffer,
310			      &ctx->u.v1.crypto_send.key,
311			      ctx->u.v1.crypto_send.seq++,
312			      message_token->value);
313	if (ret)
314	    gss_release_buffer(&junk, message_token);
315        return ret;
316
317    } else if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_ALWAYS_SIGN)) {
318	unsigned char *sigature;
319
320	sigature = message_token->value;
321
322	encode_le_uint32(1, &sigature[0]); /* version */
323	encode_le_uint32(0, &sigature[4]);
324	encode_le_uint32(0, &sigature[8]);
325	encode_le_uint32(0, &sigature[12]);
326
327        return GSS_S_COMPLETE;
328    }
329    gss_release_buffer(&junk, message_token);
330
331    return GSS_S_UNAVAILABLE;
332}
333
334/*
335 *
336 */
337
338OM_uint32 GSSAPI_CALLCONV
339_gss_ntlm_verify_mic
340           (OM_uint32 * minor_status,
341            const gss_ctx_id_t context_handle,
342            const gss_buffer_t message_buffer,
343            const gss_buffer_t token_buffer,
344            gss_qop_t * qop_state
345	    )
346{
347    ntlm_ctx ctx = (ntlm_ctx)context_handle;
348
349    if (qop_state != NULL)
350	*qop_state = GSS_C_QOP_DEFAULT;
351    *minor_status = 0;
352
353    if (token_buffer->length != 16)
354	return GSS_S_BAD_MIC;
355
356    if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SIGN|NTLM_NEG_NTLM2_SESSION)) {
357	OM_uint32 ret;
358
359	if ((ctx->status & STATUS_SESSIONKEY) == 0)
360	    return GSS_S_UNAVAILABLE;
361
362	ret = v2_verify_message(message_buffer,
363				ctx->u.v2.recv.signkey,
364				ctx->u.v2.recv.signsealkey,
365				ctx->u.v2.recv.seq++,
366				token_buffer->value);
367	if (ret)
368	    return ret;
369
370	return GSS_S_COMPLETE;
371    } else if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SIGN)) {
372
373	unsigned char sigature[12];
374	uint32_t crc, num;
375
376	if ((ctx->status & STATUS_SESSIONKEY) == 0)
377	    return GSS_S_UNAVAILABLE;
378
379	decode_le_uint32(token_buffer->value, &num);
380	if (num != 1)
381	    return GSS_S_BAD_MIC;
382
383	RC4(&ctx->u.v1.crypto_recv.key, sizeof(sigature),
384	    ((unsigned char *)token_buffer->value) + 4, sigature);
385
386	_krb5_crc_init_table();
387	crc = _krb5_crc_update(message_buffer->value,
388			       message_buffer->length, 0);
389	/* skip first 4 bytes in the encrypted checksum */
390	decode_le_uint32(&sigature[4], &num);
391	if (num != crc)
392	    return GSS_S_BAD_MIC;
393	decode_le_uint32(&sigature[8], &num);
394	if (ctx->u.v1.crypto_recv.seq != num)
395	    return GSS_S_BAD_MIC;
396	ctx->u.v1.crypto_recv.seq++;
397
398        return GSS_S_COMPLETE;
399    } else if (ctx->flags & NTLM_NEG_ALWAYS_SIGN) {
400	uint32_t num;
401	unsigned char *p;
402
403	p = (unsigned char*)(token_buffer->value);
404
405	decode_le_uint32(&p[0], &num); /* version */
406	if (num != 1) return GSS_S_BAD_MIC;
407	decode_le_uint32(&p[4], &num);
408	if (num != 0) return GSS_S_BAD_MIC;
409	decode_le_uint32(&p[8], &num);
410	if (num != 0) return GSS_S_BAD_MIC;
411	decode_le_uint32(&p[12], &num);
412	if (num != 0) return GSS_S_BAD_MIC;
413
414        return GSS_S_COMPLETE;
415    }
416
417    return GSS_S_UNAVAILABLE;
418}
419
420/*
421 *
422 */
423
424OM_uint32 GSSAPI_CALLCONV
425_gss_ntlm_wrap_size_limit (
426            OM_uint32 * minor_status,
427            const gss_ctx_id_t context_handle,
428            int conf_req_flag,
429            gss_qop_t qop_req,
430            OM_uint32 req_output_size,
431            OM_uint32 * max_input_size
432           )
433{
434    ntlm_ctx ctx = (ntlm_ctx)context_handle;
435
436    *minor_status = 0;
437
438    if(ctx->flags & NTLM_NEG_SEAL) {
439
440	if (req_output_size < 16)
441	    *max_input_size = 0;
442	else
443	    *max_input_size = req_output_size - 16;
444
445	return GSS_S_COMPLETE;
446    }
447
448    return GSS_S_UNAVAILABLE;
449}
450
451/*
452 *
453 */
454
455OM_uint32 GSSAPI_CALLCONV
456_gss_ntlm_wrap
457(OM_uint32 * minor_status,
458 const gss_ctx_id_t context_handle,
459 int conf_req_flag,
460 gss_qop_t qop_req,
461 const gss_buffer_t input_message_buffer,
462 int * conf_state,
463 gss_buffer_t output_message_buffer
464    )
465{
466    ntlm_ctx ctx = (ntlm_ctx)context_handle;
467    OM_uint32 ret;
468
469    *minor_status = 0;
470    if (conf_state)
471	*conf_state = 0;
472    if (output_message_buffer == GSS_C_NO_BUFFER)
473	return GSS_S_FAILURE;
474
475
476    if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SEAL|NTLM_NEG_NTLM2_SESSION)) {
477
478	return v2_seal_message(input_message_buffer,
479			       ctx->u.v2.send.signkey,
480			       ctx->u.v2.send.seq++,
481			       &ctx->u.v2.send.sealkey,
482			       output_message_buffer);
483
484    } else if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SEAL)) {
485	gss_buffer_desc trailer;
486	OM_uint32 junk;
487
488	output_message_buffer->length = input_message_buffer->length + 16;
489	output_message_buffer->value = malloc(output_message_buffer->length);
490	if (output_message_buffer->value == NULL) {
491	    output_message_buffer->length = 0;
492	    return GSS_S_FAILURE;
493	}
494
495
496	RC4(&ctx->u.v1.crypto_send.key, input_message_buffer->length,
497	    input_message_buffer->value, output_message_buffer->value);
498
499	ret = _gss_ntlm_get_mic(minor_status, context_handle,
500				0, input_message_buffer,
501				&trailer);
502	if (ret) {
503	    gss_release_buffer(&junk, output_message_buffer);
504	    return ret;
505	}
506	if (trailer.length != 16) {
507	    gss_release_buffer(&junk, output_message_buffer);
508	    gss_release_buffer(&junk, &trailer);
509	    return GSS_S_FAILURE;
510	}
511	memcpy(((unsigned char *)output_message_buffer->value) +
512	       input_message_buffer->length,
513	       trailer.value, trailer.length);
514	gss_release_buffer(&junk, &trailer);
515
516	return GSS_S_COMPLETE;
517    }
518
519    return GSS_S_UNAVAILABLE;
520}
521
522/*
523 *
524 */
525
526OM_uint32 GSSAPI_CALLCONV
527_gss_ntlm_unwrap
528           (OM_uint32 * minor_status,
529            const gss_ctx_id_t context_handle,
530            const gss_buffer_t input_message_buffer,
531            gss_buffer_t output_message_buffer,
532            int * conf_state,
533            gss_qop_t * qop_state
534           )
535{
536    ntlm_ctx ctx = (ntlm_ctx)context_handle;
537    OM_uint32 ret;
538
539    *minor_status = 0;
540    output_message_buffer->value = NULL;
541    output_message_buffer->length = 0;
542
543    if (conf_state)
544	*conf_state = 0;
545    if (qop_state)
546	*qop_state = 0;
547
548    if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SEAL|NTLM_NEG_NTLM2_SESSION)) {
549
550	return v2_unseal_message(input_message_buffer,
551				 ctx->u.v2.recv.signkey,
552				 ctx->u.v2.recv.seq++,
553				 &ctx->u.v2.recv.sealkey,
554				 output_message_buffer);
555
556    } else if (CTX_FLAGS_ISSET(ctx, NTLM_NEG_SEAL)) {
557
558	gss_buffer_desc trailer;
559	OM_uint32 junk;
560
561	if (input_message_buffer->length < 16)
562	    return GSS_S_BAD_MIC;
563
564	output_message_buffer->length = input_message_buffer->length - 16;
565	output_message_buffer->value = malloc(output_message_buffer->length);
566	if (output_message_buffer->value == NULL) {
567	    output_message_buffer->length = 0;
568	    return GSS_S_FAILURE;
569	}
570
571	RC4(&ctx->u.v1.crypto_recv.key, output_message_buffer->length,
572	    input_message_buffer->value, output_message_buffer->value);
573
574	trailer.value = ((unsigned char *)input_message_buffer->value) +
575	    output_message_buffer->length;
576	trailer.length = 16;
577
578	ret = _gss_ntlm_verify_mic(minor_status, context_handle,
579				   output_message_buffer,
580				   &trailer, NULL);
581	if (ret) {
582	    gss_release_buffer(&junk, output_message_buffer);
583	    return ret;
584	}
585
586	return GSS_S_COMPLETE;
587    }
588
589    return GSS_S_UNAVAILABLE;
590}
591