1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
4 * turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
5 *
6 * Copyright (c) 2000 RP Internet (www.rpi.net.au).
7 */
8
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/mm.h>
13 #include <linux/slab.h>
14 #include "cifspdu.h"
15 #include "cifsglob.h"
16 #include "cifs_debug.h"
17 #include "cifsproto.h"
18
19 /*****************************************************************************
20 *
21 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
22 *
23 *****************************************************************************/
24
25 /* Class */
26 #define ASN1_UNI 0 /* Universal */
27 #define ASN1_APL 1 /* Application */
28 #define ASN1_CTX 2 /* Context */
29 #define ASN1_PRV 3 /* Private */
30
31 /* Tag */
32 #define ASN1_EOC 0 /* End Of Contents or N/A */
33 #define ASN1_BOL 1 /* Boolean */
34 #define ASN1_INT 2 /* Integer */
35 #define ASN1_BTS 3 /* Bit String */
36 #define ASN1_OTS 4 /* Octet String */
37 #define ASN1_NUL 5 /* Null */
38 #define ASN1_OJI 6 /* Object Identifier */
39 #define ASN1_OJD 7 /* Object Description */
40 #define ASN1_EXT 8 /* External */
41 #define ASN1_ENUM 10 /* Enumerated */
42 #define ASN1_SEQ 16 /* Sequence */
43 #define ASN1_SET 17 /* Set */
44 #define ASN1_NUMSTR 18 /* Numerical String */
45 #define ASN1_PRNSTR 19 /* Printable String */
46 #define ASN1_TEXSTR 20 /* Teletext String */
47 #define ASN1_VIDSTR 21 /* Video String */
48 #define ASN1_IA5STR 22 /* IA5 String */
49 #define ASN1_UNITIM 23 /* Universal Time */
50 #define ASN1_GENTIM 24 /* General Time */
51 #define ASN1_GRASTR 25 /* Graphical String */
52 #define ASN1_VISSTR 26 /* Visible String */
53 #define ASN1_GENSTR 27 /* General String */
54
55 /* Primitive / Constructed methods*/
56 #define ASN1_PRI 0 /* Primitive */
57 #define ASN1_CON 1 /* Constructed */
58
59 /*
60 * Error codes.
61 */
62 #define ASN1_ERR_NOERROR 0
63 #define ASN1_ERR_DEC_EMPTY 2
64 #define ASN1_ERR_DEC_EOC_MISMATCH 3
65 #define ASN1_ERR_DEC_LENGTH_MISMATCH 4
66 #define ASN1_ERR_DEC_BADVALUE 5
67
68 #define SPNEGO_OID_LEN 7
69 #define NTLMSSP_OID_LEN 10
70 #define KRB5_OID_LEN 7
71 #define KRB5U2U_OID_LEN 8
72 #define MSKRB5_OID_LEN 7
73 static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
74 static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
75 static unsigned long KRB5_OID[7] = { 1, 2, 840, 113554, 1, 2, 2 };
76 static unsigned long KRB5U2U_OID[8] = { 1, 2, 840, 113554, 1, 2, 2, 3 };
77 static unsigned long MSKRB5_OID[7] = { 1, 2, 840, 48018, 1, 2, 2 };
78
79 /*
80 * ASN.1 context.
81 */
82 struct asn1_ctx {
83 int error; /* Error condition */
84 unsigned char *pointer; /* Octet just to be decoded */
85 unsigned char *begin; /* First octet */
86 unsigned char *end; /* Octet after last octet */
87 };
88
89 /*
90 * Octet string (not null terminated)
91 */
92 struct asn1_octstr {
93 unsigned char *data;
94 unsigned int len;
95 };
96
97 static void
asn1_open(struct asn1_ctx * ctx,unsigned char * buf,unsigned int len)98 asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
99 {
100 ctx->begin = buf;
101 ctx->end = buf + len;
102 ctx->pointer = buf;
103 ctx->error = ASN1_ERR_NOERROR;
104 }
105
106 static unsigned char
asn1_octet_decode(struct asn1_ctx * ctx,unsigned char * ch)107 asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
108 {
109 if (ctx->pointer >= ctx->end) {
110 ctx->error = ASN1_ERR_DEC_EMPTY;
111 return 0;
112 }
113 *ch = *(ctx->pointer)++;
114 return 1;
115 }
116
117 #if 0 /* will be needed later by spnego decoding/encoding of ntlmssp */
118 static unsigned char
119 asn1_enum_decode(struct asn1_ctx *ctx, __le32 *val)
120 {
121 unsigned char ch;
122
123 if (ctx->pointer >= ctx->end) {
124 ctx->error = ASN1_ERR_DEC_EMPTY;
125 return 0;
126 }
127
128 ch = *(ctx->pointer)++; /* ch has 0xa, ptr points to length octet */
129 if ((ch) == ASN1_ENUM) /* if ch value is ENUM, 0xa */
130 *val = *(++(ctx->pointer)); /* value has enum value */
131 else
132 return 0;
133
134 ctx->pointer++;
135 return 1;
136 }
137 #endif
138
139 static unsigned char
asn1_tag_decode(struct asn1_ctx * ctx,unsigned int * tag)140 asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
141 {
142 unsigned char ch;
143
144 *tag = 0;
145
146 do {
147 if (!asn1_octet_decode(ctx, &ch))
148 return 0;
149 *tag <<= 7;
150 *tag |= ch & 0x7F;
151 } while ((ch & 0x80) == 0x80);
152 return 1;
153 }
154
155 static unsigned char
asn1_id_decode(struct asn1_ctx * ctx,unsigned int * cls,unsigned int * con,unsigned int * tag)156 asn1_id_decode(struct asn1_ctx *ctx,
157 unsigned int *cls, unsigned int *con, unsigned int *tag)
158 {
159 unsigned char ch;
160
161 if (!asn1_octet_decode(ctx, &ch))
162 return 0;
163
164 *cls = (ch & 0xC0) >> 6;
165 *con = (ch & 0x20) >> 5;
166 *tag = (ch & 0x1F);
167
168 if (*tag == 0x1F) {
169 if (!asn1_tag_decode(ctx, tag))
170 return 0;
171 }
172 return 1;
173 }
174
175 static unsigned char
asn1_length_decode(struct asn1_ctx * ctx,unsigned int * def,unsigned int * len)176 asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
177 {
178 unsigned char ch, cnt;
179
180 if (!asn1_octet_decode(ctx, &ch))
181 return 0;
182
183 if (ch == 0x80)
184 *def = 0;
185 else {
186 *def = 1;
187
188 if (ch < 0x80)
189 *len = ch;
190 else {
191 cnt = (unsigned char) (ch & 0x7F);
192 *len = 0;
193
194 while (cnt > 0) {
195 if (!asn1_octet_decode(ctx, &ch))
196 return 0;
197 *len <<= 8;
198 *len |= ch;
199 cnt--;
200 }
201 }
202 }
203
204 /* don't trust len bigger than ctx buffer */
205 if (*len > ctx->end - ctx->pointer)
206 return 0;
207
208 return 1;
209 }
210
211 static unsigned char
asn1_header_decode(struct asn1_ctx * ctx,unsigned char ** eoc,unsigned int * cls,unsigned int * con,unsigned int * tag)212 asn1_header_decode(struct asn1_ctx *ctx,
213 unsigned char **eoc,
214 unsigned int *cls, unsigned int *con, unsigned int *tag)
215 {
216 unsigned int def = 0;
217 unsigned int len = 0;
218
219 if (!asn1_id_decode(ctx, cls, con, tag))
220 return 0;
221
222 if (!asn1_length_decode(ctx, &def, &len))
223 return 0;
224
225 /* primitive shall be definite, indefinite shall be constructed */
226 if (*con == ASN1_PRI && !def)
227 return 0;
228
229 if (def)
230 *eoc = ctx->pointer + len;
231 else
232 *eoc = NULL;
233 return 1;
234 }
235
236 static unsigned char
asn1_eoc_decode(struct asn1_ctx * ctx,unsigned char * eoc)237 asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
238 {
239 unsigned char ch;
240
241 if (eoc == NULL) {
242 if (!asn1_octet_decode(ctx, &ch))
243 return 0;
244
245 if (ch != 0x00) {
246 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
247 return 0;
248 }
249
250 if (!asn1_octet_decode(ctx, &ch))
251 return 0;
252
253 if (ch != 0x00) {
254 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
255 return 0;
256 }
257 return 1;
258 } else {
259 if (ctx->pointer != eoc) {
260 ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
261 return 0;
262 }
263 return 1;
264 }
265 }
266
267 /* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
268 unsigned char *eoc)
269 {
270 ctx->pointer = eoc;
271 return 1;
272 }
273
274 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
275 unsigned char *eoc, long *integer)
276 {
277 unsigned char ch;
278 unsigned int len;
279
280 if (!asn1_octet_decode(ctx, &ch))
281 return 0;
282
283 *integer = (signed char) ch;
284 len = 1;
285
286 while (ctx->pointer < eoc) {
287 if (++len > sizeof(long)) {
288 ctx->error = ASN1_ERR_DEC_BADVALUE;
289 return 0;
290 }
291
292 if (!asn1_octet_decode(ctx, &ch))
293 return 0;
294
295 *integer <<= 8;
296 *integer |= ch;
297 }
298 return 1;
299 }
300
301 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
302 unsigned char *eoc,
303 unsigned int *integer)
304 {
305 unsigned char ch;
306 unsigned int len;
307
308 if (!asn1_octet_decode(ctx, &ch))
309 return 0;
310
311 *integer = ch;
312 if (ch == 0)
313 len = 0;
314 else
315 len = 1;
316
317 while (ctx->pointer < eoc) {
318 if (++len > sizeof(unsigned int)) {
319 ctx->error = ASN1_ERR_DEC_BADVALUE;
320 return 0;
321 }
322
323 if (!asn1_octet_decode(ctx, &ch))
324 return 0;
325
326 *integer <<= 8;
327 *integer |= ch;
328 }
329 return 1;
330 }
331
332 static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
333 unsigned char *eoc,
334 unsigned long *integer)
335 {
336 unsigned char ch;
337 unsigned int len;
338
339 if (!asn1_octet_decode(ctx, &ch))
340 return 0;
341
342 *integer = ch;
343 if (ch == 0)
344 len = 0;
345 else
346 len = 1;
347
348 while (ctx->pointer < eoc) {
349 if (++len > sizeof(unsigned long)) {
350 ctx->error = ASN1_ERR_DEC_BADVALUE;
351 return 0;
352 }
353
354 if (!asn1_octet_decode(ctx, &ch))
355 return 0;
356
357 *integer <<= 8;
358 *integer |= ch;
359 }
360 return 1;
361 }
362
363 static unsigned char
364 asn1_octets_decode(struct asn1_ctx *ctx,
365 unsigned char *eoc,
366 unsigned char **octets, unsigned int *len)
367 {
368 unsigned char *ptr;
369
370 *len = 0;
371
372 *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
373 if (*octets == NULL) {
374 return 0;
375 }
376
377 ptr = *octets;
378 while (ctx->pointer < eoc) {
379 if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
380 kfree(*octets);
381 *octets = NULL;
382 return 0;
383 }
384 (*len)++;
385 }
386 return 1;
387 } */
388
389 static unsigned char
asn1_subid_decode(struct asn1_ctx * ctx,unsigned long * subid)390 asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
391 {
392 unsigned char ch;
393
394 *subid = 0;
395
396 do {
397 if (!asn1_octet_decode(ctx, &ch))
398 return 0;
399
400 *subid <<= 7;
401 *subid |= ch & 0x7F;
402 } while ((ch & 0x80) == 0x80);
403 return 1;
404 }
405
406 static int
asn1_oid_decode(struct asn1_ctx * ctx,unsigned char * eoc,unsigned long ** oid,unsigned int * len)407 asn1_oid_decode(struct asn1_ctx *ctx,
408 unsigned char *eoc, unsigned long **oid, unsigned int *len)
409 {
410 unsigned long subid;
411 unsigned int size;
412 unsigned long *optr;
413
414 size = eoc - ctx->pointer + 1;
415
416 /* first subid actually encodes first two subids */
417 if (size < 2 || size > UINT_MAX/sizeof(unsigned long))
418 return 0;
419
420 *oid = kmalloc_array(size, sizeof(unsigned long), GFP_ATOMIC);
421 if (*oid == NULL)
422 return 0;
423
424 optr = *oid;
425
426 if (!asn1_subid_decode(ctx, &subid)) {
427 kfree(*oid);
428 *oid = NULL;
429 return 0;
430 }
431
432 if (subid < 40) {
433 optr[0] = 0;
434 optr[1] = subid;
435 } else if (subid < 80) {
436 optr[0] = 1;
437 optr[1] = subid - 40;
438 } else {
439 optr[0] = 2;
440 optr[1] = subid - 80;
441 }
442
443 *len = 2;
444 optr += 2;
445
446 while (ctx->pointer < eoc) {
447 if (++(*len) > size) {
448 ctx->error = ASN1_ERR_DEC_BADVALUE;
449 kfree(*oid);
450 *oid = NULL;
451 return 0;
452 }
453
454 if (!asn1_subid_decode(ctx, optr++)) {
455 kfree(*oid);
456 *oid = NULL;
457 return 0;
458 }
459 }
460 return 1;
461 }
462
463 static int
compare_oid(unsigned long * oid1,unsigned int oid1len,unsigned long * oid2,unsigned int oid2len)464 compare_oid(unsigned long *oid1, unsigned int oid1len,
465 unsigned long *oid2, unsigned int oid2len)
466 {
467 unsigned int i;
468
469 if (oid1len != oid2len)
470 return 0;
471 else {
472 for (i = 0; i < oid1len; i++) {
473 if (oid1[i] != oid2[i])
474 return 0;
475 }
476 return 1;
477 }
478 }
479
480 /* BB check for endian conversion issues here */
481
482 int
decode_negTokenInit(unsigned char * security_blob,int length,struct TCP_Server_Info * server)483 decode_negTokenInit(unsigned char *security_blob, int length,
484 struct TCP_Server_Info *server)
485 {
486 struct asn1_ctx ctx;
487 unsigned char *end;
488 unsigned char *sequence_end;
489 unsigned long *oid = NULL;
490 unsigned int cls, con, tag, oidlen, rc;
491
492 /* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
493
494 asn1_open(&ctx, security_blob, length);
495
496 /* GSSAPI header */
497 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
498 cifs_dbg(FYI, "Error decoding negTokenInit header\n");
499 return 0;
500 } else if ((cls != ASN1_APL) || (con != ASN1_CON)
501 || (tag != ASN1_EOC)) {
502 cifs_dbg(FYI, "cls = %d con = %d tag = %d\n", cls, con, tag);
503 return 0;
504 }
505
506 /* Check for SPNEGO OID -- remember to free obj->oid */
507 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
508 if (rc) {
509 if ((tag == ASN1_OJI) && (con == ASN1_PRI) &&
510 (cls == ASN1_UNI)) {
511 rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
512 if (rc) {
513 rc = compare_oid(oid, oidlen, SPNEGO_OID,
514 SPNEGO_OID_LEN);
515 kfree(oid);
516 }
517 } else
518 rc = 0;
519 }
520
521 /* SPNEGO OID not present or garbled -- bail out */
522 if (!rc) {
523 cifs_dbg(FYI, "Error decoding negTokenInit header\n");
524 return 0;
525 }
526
527 /* SPNEGO */
528 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
529 cifs_dbg(FYI, "Error decoding negTokenInit\n");
530 return 0;
531 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
532 || (tag != ASN1_EOC)) {
533 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 0\n",
534 cls, con, tag, end, *end);
535 return 0;
536 }
537
538 /* negTokenInit */
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_UNI) || (con != ASN1_CON)
543 || (tag != ASN1_SEQ)) {
544 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 1\n",
545 cls, con, tag, end, *end);
546 return 0;
547 }
548
549 /* sequence */
550 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
551 cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
552 return 0;
553 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
554 || (tag != ASN1_EOC)) {
555 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 0\n",
556 cls, con, tag, end, *end);
557 return 0;
558 }
559
560 /* sequence of */
561 if (asn1_header_decode
562 (&ctx, &sequence_end, &cls, &con, &tag) == 0) {
563 cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
564 return 0;
565 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
566 || (tag != ASN1_SEQ)) {
567 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 1\n",
568 cls, con, tag, end, *end);
569 return 0;
570 }
571
572 /* list of security mechanisms */
573 while (!asn1_eoc_decode(&ctx, sequence_end)) {
574 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
575 if (!rc) {
576 cifs_dbg(FYI, "Error decoding negTokenInit hdr exit2\n");
577 return 0;
578 }
579 if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
580 if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {
581
582 cifs_dbg(FYI, "OID len = %d oid = 0x%lx 0x%lx 0x%lx 0x%lx\n",
583 oidlen, *oid, *(oid + 1), *(oid + 2),
584 *(oid + 3));
585
586 if (compare_oid(oid, oidlen, MSKRB5_OID,
587 MSKRB5_OID_LEN))
588 server->sec_mskerberos = true;
589 else if (compare_oid(oid, oidlen, KRB5U2U_OID,
590 KRB5U2U_OID_LEN))
591 server->sec_kerberosu2u = true;
592 else if (compare_oid(oid, oidlen, KRB5_OID,
593 KRB5_OID_LEN))
594 server->sec_kerberos = true;
595 else if (compare_oid(oid, oidlen, NTLMSSP_OID,
596 NTLMSSP_OID_LEN))
597 server->sec_ntlmssp = true;
598
599 kfree(oid);
600 }
601 } else {
602 cifs_dbg(FYI, "Should be an oid what is going on?\n");
603 }
604 }
605
606 /*
607 * We currently ignore anything at the end of the SPNEGO blob after
608 * the mechTypes have been parsed, since none of that info is
609 * used at the moment.
610 */
611 return 1;
612 }
613