1 /*
2 * The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
3 * turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
4 *
5 * Copyright (c) 2000 RP Internet (www.rpi.net.au).
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20 #include <linux/module.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/mm.h>
24 #include <linux/slab.h>
25 #include "cifspdu.h"
26 #include "cifsglob.h"
27 #include "cifs_debug.h"
28 #include "cifsproto.h"
29
30 /*****************************************************************************
31 *
32 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
33 *
34 *****************************************************************************/
35
36 /* Class */
37 #define ASN1_UNI 0 /* Universal */
38 #define ASN1_APL 1 /* Application */
39 #define ASN1_CTX 2 /* Context */
40 #define ASN1_PRV 3 /* Private */
41
42 /* Tag */
43 #define ASN1_EOC 0 /* End Of Contents or N/A */
44 #define ASN1_BOL 1 /* Boolean */
45 #define ASN1_INT 2 /* Integer */
46 #define ASN1_BTS 3 /* Bit String */
47 #define ASN1_OTS 4 /* Octet String */
48 #define ASN1_NUL 5 /* Null */
49 #define ASN1_OJI 6 /* Object Identifier */
50 #define ASN1_OJD 7 /* Object Description */
51 #define ASN1_EXT 8 /* External */
52 #define ASN1_ENUM 10 /* Enumerated */
53 #define ASN1_SEQ 16 /* Sequence */
54 #define ASN1_SET 17 /* Set */
55 #define ASN1_NUMSTR 18 /* Numerical String */
56 #define ASN1_PRNSTR 19 /* Printable String */
57 #define ASN1_TEXSTR 20 /* Teletext String */
58 #define ASN1_VIDSTR 21 /* Video String */
59 #define ASN1_IA5STR 22 /* IA5 String */
60 #define ASN1_UNITIM 23 /* Universal Time */
61 #define ASN1_GENTIM 24 /* General Time */
62 #define ASN1_GRASTR 25 /* Graphical String */
63 #define ASN1_VISSTR 26 /* Visible String */
64 #define ASN1_GENSTR 27 /* General String */
65
66 /* Primitive / Constructed methods*/
67 #define ASN1_PRI 0 /* Primitive */
68 #define ASN1_CON 1 /* Constructed */
69
70 /*
71 * Error codes.
72 */
73 #define ASN1_ERR_NOERROR 0
74 #define ASN1_ERR_DEC_EMPTY 2
75 #define ASN1_ERR_DEC_EOC_MISMATCH 3
76 #define ASN1_ERR_DEC_LENGTH_MISMATCH 4
77 #define ASN1_ERR_DEC_BADVALUE 5
78
79 #define SPNEGO_OID_LEN 7
80 #define NTLMSSP_OID_LEN 10
81 #define KRB5_OID_LEN 7
82 #define KRB5U2U_OID_LEN 8
83 #define MSKRB5_OID_LEN 7
84 static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
85 static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
86 static unsigned long KRB5_OID[7] = { 1, 2, 840, 113554, 1, 2, 2 };
87 static unsigned long KRB5U2U_OID[8] = { 1, 2, 840, 113554, 1, 2, 2, 3 };
88 static unsigned long MSKRB5_OID[7] = { 1, 2, 840, 48018, 1, 2, 2 };
89
90 /*
91 * ASN.1 context.
92 */
93 struct asn1_ctx {
94 int error; /* Error condition */
95 unsigned char *pointer; /* Octet just to be decoded */
96 unsigned char *begin; /* First octet */
97 unsigned char *end; /* Octet after last octet */
98 };
99
100 /*
101 * Octet string (not null terminated)
102 */
103 struct asn1_octstr {
104 unsigned char *data;
105 unsigned int len;
106 };
107
108 static void
asn1_open(struct asn1_ctx * ctx,unsigned char * buf,unsigned int len)109 asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
110 {
111 ctx->begin = buf;
112 ctx->end = buf + len;
113 ctx->pointer = buf;
114 ctx->error = ASN1_ERR_NOERROR;
115 }
116
117 static unsigned char
asn1_octet_decode(struct asn1_ctx * ctx,unsigned char * ch)118 asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
119 {
120 if (ctx->pointer >= ctx->end) {
121 ctx->error = ASN1_ERR_DEC_EMPTY;
122 return 0;
123 }
124 *ch = *(ctx->pointer)++;
125 return 1;
126 }
127
128 #if 0 /* will be needed later by spnego decoding/encoding of ntlmssp */
129 static unsigned char
130 asn1_enum_decode(struct asn1_ctx *ctx, __le32 *val)
131 {
132 unsigned char ch;
133
134 if (ctx->pointer >= ctx->end) {
135 ctx->error = ASN1_ERR_DEC_EMPTY;
136 return 0;
137 }
138
139 ch = *(ctx->pointer)++; /* ch has 0xa, ptr points to length octet */
140 if ((ch) == ASN1_ENUM) /* if ch value is ENUM, 0xa */
141 *val = *(++(ctx->pointer)); /* value has enum value */
142 else
143 return 0;
144
145 ctx->pointer++;
146 return 1;
147 }
148 #endif
149
150 static unsigned char
asn1_tag_decode(struct asn1_ctx * ctx,unsigned int * tag)151 asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
152 {
153 unsigned char ch;
154
155 *tag = 0;
156
157 do {
158 if (!asn1_octet_decode(ctx, &ch))
159 return 0;
160 *tag <<= 7;
161 *tag |= ch & 0x7F;
162 } while ((ch & 0x80) == 0x80);
163 return 1;
164 }
165
166 static unsigned char
asn1_id_decode(struct asn1_ctx * ctx,unsigned int * cls,unsigned int * con,unsigned int * tag)167 asn1_id_decode(struct asn1_ctx *ctx,
168 unsigned int *cls, unsigned int *con, unsigned int *tag)
169 {
170 unsigned char ch;
171
172 if (!asn1_octet_decode(ctx, &ch))
173 return 0;
174
175 *cls = (ch & 0xC0) >> 6;
176 *con = (ch & 0x20) >> 5;
177 *tag = (ch & 0x1F);
178
179 if (*tag == 0x1F) {
180 if (!asn1_tag_decode(ctx, tag))
181 return 0;
182 }
183 return 1;
184 }
185
186 static unsigned char
asn1_length_decode(struct asn1_ctx * ctx,unsigned int * def,unsigned int * len)187 asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
188 {
189 unsigned char ch, cnt;
190
191 if (!asn1_octet_decode(ctx, &ch))
192 return 0;
193
194 if (ch == 0x80)
195 *def = 0;
196 else {
197 *def = 1;
198
199 if (ch < 0x80)
200 *len = ch;
201 else {
202 cnt = (unsigned char) (ch & 0x7F);
203 *len = 0;
204
205 while (cnt > 0) {
206 if (!asn1_octet_decode(ctx, &ch))
207 return 0;
208 *len <<= 8;
209 *len |= ch;
210 cnt--;
211 }
212 }
213 }
214
215 /* don't trust len bigger than ctx buffer */
216 if (*len > ctx->end - ctx->pointer)
217 return 0;
218
219 return 1;
220 }
221
222 static unsigned char
asn1_header_decode(struct asn1_ctx * ctx,unsigned char ** eoc,unsigned int * cls,unsigned int * con,unsigned int * tag)223 asn1_header_decode(struct asn1_ctx *ctx,
224 unsigned char **eoc,
225 unsigned int *cls, unsigned int *con, unsigned int *tag)
226 {
227 unsigned int def = 0;
228 unsigned int len = 0;
229
230 if (!asn1_id_decode(ctx, cls, con, tag))
231 return 0;
232
233 if (!asn1_length_decode(ctx, &def, &len))
234 return 0;
235
236 /* primitive shall be definite, indefinite shall be constructed */
237 if (*con == ASN1_PRI && !def)
238 return 0;
239
240 if (def)
241 *eoc = ctx->pointer + len;
242 else
243 *eoc = NULL;
244 return 1;
245 }
246
247 static unsigned char
asn1_eoc_decode(struct asn1_ctx * ctx,unsigned char * eoc)248 asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
249 {
250 unsigned char ch;
251
252 if (eoc == NULL) {
253 if (!asn1_octet_decode(ctx, &ch))
254 return 0;
255
256 if (ch != 0x00) {
257 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
258 return 0;
259 }
260
261 if (!asn1_octet_decode(ctx, &ch))
262 return 0;
263
264 if (ch != 0x00) {
265 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
266 return 0;
267 }
268 return 1;
269 } else {
270 if (ctx->pointer != eoc) {
271 ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
272 return 0;
273 }
274 return 1;
275 }
276 }
277
278 /* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
279 unsigned char *eoc)
280 {
281 ctx->pointer = eoc;
282 return 1;
283 }
284
285 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
286 unsigned char *eoc, long *integer)
287 {
288 unsigned char ch;
289 unsigned int len;
290
291 if (!asn1_octet_decode(ctx, &ch))
292 return 0;
293
294 *integer = (signed char) ch;
295 len = 1;
296
297 while (ctx->pointer < eoc) {
298 if (++len > sizeof(long)) {
299 ctx->error = ASN1_ERR_DEC_BADVALUE;
300 return 0;
301 }
302
303 if (!asn1_octet_decode(ctx, &ch))
304 return 0;
305
306 *integer <<= 8;
307 *integer |= ch;
308 }
309 return 1;
310 }
311
312 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
313 unsigned char *eoc,
314 unsigned int *integer)
315 {
316 unsigned char ch;
317 unsigned int len;
318
319 if (!asn1_octet_decode(ctx, &ch))
320 return 0;
321
322 *integer = ch;
323 if (ch == 0)
324 len = 0;
325 else
326 len = 1;
327
328 while (ctx->pointer < eoc) {
329 if (++len > sizeof(unsigned int)) {
330 ctx->error = ASN1_ERR_DEC_BADVALUE;
331 return 0;
332 }
333
334 if (!asn1_octet_decode(ctx, &ch))
335 return 0;
336
337 *integer <<= 8;
338 *integer |= ch;
339 }
340 return 1;
341 }
342
343 static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
344 unsigned char *eoc,
345 unsigned long *integer)
346 {
347 unsigned char ch;
348 unsigned int len;
349
350 if (!asn1_octet_decode(ctx, &ch))
351 return 0;
352
353 *integer = ch;
354 if (ch == 0)
355 len = 0;
356 else
357 len = 1;
358
359 while (ctx->pointer < eoc) {
360 if (++len > sizeof(unsigned long)) {
361 ctx->error = ASN1_ERR_DEC_BADVALUE;
362 return 0;
363 }
364
365 if (!asn1_octet_decode(ctx, &ch))
366 return 0;
367
368 *integer <<= 8;
369 *integer |= ch;
370 }
371 return 1;
372 }
373
374 static unsigned char
375 asn1_octets_decode(struct asn1_ctx *ctx,
376 unsigned char *eoc,
377 unsigned char **octets, unsigned int *len)
378 {
379 unsigned char *ptr;
380
381 *len = 0;
382
383 *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
384 if (*octets == NULL) {
385 return 0;
386 }
387
388 ptr = *octets;
389 while (ctx->pointer < eoc) {
390 if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
391 kfree(*octets);
392 *octets = NULL;
393 return 0;
394 }
395 (*len)++;
396 }
397 return 1;
398 } */
399
400 static unsigned char
asn1_subid_decode(struct asn1_ctx * ctx,unsigned long * subid)401 asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
402 {
403 unsigned char ch;
404
405 *subid = 0;
406
407 do {
408 if (!asn1_octet_decode(ctx, &ch))
409 return 0;
410
411 *subid <<= 7;
412 *subid |= ch & 0x7F;
413 } while ((ch & 0x80) == 0x80);
414 return 1;
415 }
416
417 static int
asn1_oid_decode(struct asn1_ctx * ctx,unsigned char * eoc,unsigned long ** oid,unsigned int * len)418 asn1_oid_decode(struct asn1_ctx *ctx,
419 unsigned char *eoc, unsigned long **oid, unsigned int *len)
420 {
421 unsigned long subid;
422 unsigned int size;
423 unsigned long *optr;
424
425 size = eoc - ctx->pointer + 1;
426
427 /* first subid actually encodes first two subids */
428 if (size < 2 || size > UINT_MAX/sizeof(unsigned long))
429 return 0;
430
431 *oid = kmalloc_array(size, sizeof(unsigned long), GFP_ATOMIC);
432 if (*oid == NULL)
433 return 0;
434
435 optr = *oid;
436
437 if (!asn1_subid_decode(ctx, &subid)) {
438 kfree(*oid);
439 *oid = NULL;
440 return 0;
441 }
442
443 if (subid < 40) {
444 optr[0] = 0;
445 optr[1] = subid;
446 } else if (subid < 80) {
447 optr[0] = 1;
448 optr[1] = subid - 40;
449 } else {
450 optr[0] = 2;
451 optr[1] = subid - 80;
452 }
453
454 *len = 2;
455 optr += 2;
456
457 while (ctx->pointer < eoc) {
458 if (++(*len) > size) {
459 ctx->error = ASN1_ERR_DEC_BADVALUE;
460 kfree(*oid);
461 *oid = NULL;
462 return 0;
463 }
464
465 if (!asn1_subid_decode(ctx, optr++)) {
466 kfree(*oid);
467 *oid = NULL;
468 return 0;
469 }
470 }
471 return 1;
472 }
473
474 static int
compare_oid(unsigned long * oid1,unsigned int oid1len,unsigned long * oid2,unsigned int oid2len)475 compare_oid(unsigned long *oid1, unsigned int oid1len,
476 unsigned long *oid2, unsigned int oid2len)
477 {
478 unsigned int i;
479
480 if (oid1len != oid2len)
481 return 0;
482 else {
483 for (i = 0; i < oid1len; i++) {
484 if (oid1[i] != oid2[i])
485 return 0;
486 }
487 return 1;
488 }
489 }
490
491 /* BB check for endian conversion issues here */
492
493 int
decode_negTokenInit(unsigned char * security_blob,int length,struct TCP_Server_Info * server)494 decode_negTokenInit(unsigned char *security_blob, int length,
495 struct TCP_Server_Info *server)
496 {
497 struct asn1_ctx ctx;
498 unsigned char *end;
499 unsigned char *sequence_end;
500 unsigned long *oid = NULL;
501 unsigned int cls, con, tag, oidlen, rc;
502
503 /* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
504
505 asn1_open(&ctx, security_blob, length);
506
507 /* GSSAPI header */
508 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
509 cifs_dbg(FYI, "Error decoding negTokenInit header\n");
510 return 0;
511 } else if ((cls != ASN1_APL) || (con != ASN1_CON)
512 || (tag != ASN1_EOC)) {
513 cifs_dbg(FYI, "cls = %d con = %d tag = %d\n", cls, con, tag);
514 return 0;
515 }
516
517 /* Check for SPNEGO OID -- remember to free obj->oid */
518 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
519 if (rc) {
520 if ((tag == ASN1_OJI) && (con == ASN1_PRI) &&
521 (cls == ASN1_UNI)) {
522 rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
523 if (rc) {
524 rc = compare_oid(oid, oidlen, SPNEGO_OID,
525 SPNEGO_OID_LEN);
526 kfree(oid);
527 }
528 } else
529 rc = 0;
530 }
531
532 /* SPNEGO OID not present or garbled -- bail out */
533 if (!rc) {
534 cifs_dbg(FYI, "Error decoding negTokenInit header\n");
535 return 0;
536 }
537
538 /* SPNEGO */
539 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
540 cifs_dbg(FYI, "Error decoding negTokenInit\n");
541 return 0;
542 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
543 || (tag != ASN1_EOC)) {
544 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p exit 0\n",
545 cls, con, tag, end);
546 return 0;
547 }
548
549 /* negTokenInit */
550 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
551 cifs_dbg(FYI, "Error decoding negTokenInit\n");
552 return 0;
553 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
554 || (tag != ASN1_SEQ)) {
555 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p exit 1\n",
556 cls, con, tag, end);
557 return 0;
558 }
559
560 /* sequence */
561 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
562 cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
563 return 0;
564 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
565 || (tag != ASN1_EOC)) {
566 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p exit 0\n",
567 cls, con, tag, end);
568 return 0;
569 }
570
571 /* sequence of */
572 if (asn1_header_decode
573 (&ctx, &sequence_end, &cls, &con, &tag) == 0) {
574 cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
575 return 0;
576 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
577 || (tag != ASN1_SEQ)) {
578 cifs_dbg(FYI, "cls = %d con = %d tag = %d sequence_end = %p exit 1\n",
579 cls, con, tag, sequence_end);
580 return 0;
581 }
582
583 /* list of security mechanisms */
584 while (!asn1_eoc_decode(&ctx, sequence_end)) {
585 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
586 if (!rc) {
587 cifs_dbg(FYI, "Error decoding negTokenInit hdr exit2\n");
588 return 0;
589 }
590 if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
591 if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {
592
593 cifs_dbg(FYI, "OID len = %d oid = 0x%lx 0x%lx 0x%lx 0x%lx\n",
594 oidlen, *oid, *(oid + 1), *(oid + 2),
595 *(oid + 3));
596
597 if (compare_oid(oid, oidlen, MSKRB5_OID,
598 MSKRB5_OID_LEN))
599 server->sec_mskerberos = true;
600 else if (compare_oid(oid, oidlen, KRB5U2U_OID,
601 KRB5U2U_OID_LEN))
602 server->sec_kerberosu2u = true;
603 else if (compare_oid(oid, oidlen, KRB5_OID,
604 KRB5_OID_LEN))
605 server->sec_kerberos = true;
606 else if (compare_oid(oid, oidlen, NTLMSSP_OID,
607 NTLMSSP_OID_LEN))
608 server->sec_ntlmssp = true;
609
610 kfree(oid);
611 }
612 } else {
613 cifs_dbg(FYI, "Should be an oid what is going on?\n");
614 }
615 }
616
617 /*
618 * We currently ignore anything at the end of the SPNEGO blob after
619 * the mechTypes have been parsed, since none of that info is
620 * used at the moment.
621 */
622 return 1;
623 }
624