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GUI: Fix Tomato RAF theme for all builds. Compilation typo.
[tomato.git] / release / src-rt-6.x.4708 / linux / linux-2.6.36 / net / ipv4 / netfilter / nf_nat_snmp_basic.c
blobee5f419d0a56d01c6533d6ee45f70a7405480150
1 /*
2 * nf_nat_snmp_basic.c
3 *
4 * Basic SNMP Application Layer Gateway
5 *
6 * This IP NAT module is intended for use with SNMP network
7 * discovery and monitoring applications where target networks use
8 * conflicting private address realms.
9 *
10 * Static NAT is used to remap the networks from the view of the network
11 * management system at the IP layer, and this module remaps some application
12 * layer addresses to match.
13 *
14 * The simplest form of ALG is performed, where only tagged IP addresses
15 * are modified. The module does not need to be MIB aware and only scans
16 * messages at the ASN.1/BER level.
17 *
18 * Currently, only SNMPv1 and SNMPv2 are supported.
19 *
20 * More information on ALG and associated issues can be found in
21 * RFC 2962
22 *
23 * The ASB.1/BER parsing code is derived from the gxsnmp package by Gregory
24 * McLean & Jochen Friedrich, stripped down for use in the kernel.
25 *
26 * Copyright (c) 2000 RP Internet (www.rpi.net.au).
27 *
28 * This program is free software; you can redistribute it and/or modify
29 * it under the terms of the GNU General Public License as published by
30 * the Free Software Foundation; either version 2 of the License, or
31 * (at your option) any later version.
32 * This program is distributed in the hope that it will be useful,
33 * but WITHOUT ANY WARRANTY; without even the implied warranty of
34 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
35 * GNU General Public License for more details.
36 * You should have received a copy of the GNU General Public License
37 * along with this program; if not, write to the Free Software
38 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
39 *
40 * Author: James Morris <jmorris@intercode.com.au>
41 */
42 #include <linux/module.h>
43 #include <linux/moduleparam.h>
44 #include <linux/types.h>
45 #include <linux/kernel.h>
46 #include <linux/slab.h>
47 #include <linux/in.h>
48 #include <linux/ip.h>
49 #include <linux/udp.h>
50 #include <net/checksum.h>
51 #include <net/udp.h>
52
53 #include <net/netfilter/nf_nat.h>
54 #include <net/netfilter/nf_conntrack_expect.h>
55 #include <net/netfilter/nf_conntrack_helper.h>
56 #include <net/netfilter/nf_nat_helper.h>
57
58 MODULE_LICENSE("GPL");
59 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
60 MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway");
61 MODULE_ALIAS("ip_nat_snmp_basic");
62
63 #define SNMP_PORT 161
64 #define SNMP_TRAP_PORT 162
65 #define NOCT1(n) (*(u8 *)(n))
66
67 static int debug;
68 static DEFINE_SPINLOCK(snmp_lock);
69
70 /*
71 * Application layer address mapping mimics the NAT mapping, but
72 * only for the first octet in this case (a more flexible system
73 * can be implemented if needed).
74 */
75 struct oct1_map
76 {
77 u_int8_t from;
78 u_int8_t to;
79 };
80
81
82 /*****************************************************************************
83 *
84 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
85 *
86 *****************************************************************************/
87
88 /* Class */
89 #define ASN1_UNI 0 /* Universal */
90 #define ASN1_APL 1 /* Application */
91 #define ASN1_CTX 2 /* Context */
92 #define ASN1_PRV 3 /* Private */
93
94 /* Tag */
95 #define ASN1_EOC 0 /* End Of Contents */
96 #define ASN1_BOL 1 /* Boolean */
97 #define ASN1_INT 2 /* Integer */
98 #define ASN1_BTS 3 /* Bit String */
99 #define ASN1_OTS 4 /* Octet String */
100 #define ASN1_NUL 5 /* Null */
101 #define ASN1_OJI 6 /* Object Identifier */
102 #define ASN1_OJD 7 /* Object Description */
103 #define ASN1_EXT 8 /* External */
104 #define ASN1_SEQ 16 /* Sequence */
105 #define ASN1_SET 17 /* Set */
106 #define ASN1_NUMSTR 18 /* Numerical String */
107 #define ASN1_PRNSTR 19 /* Printable String */
108 #define ASN1_TEXSTR 20 /* Teletext String */
109 #define ASN1_VIDSTR 21 /* Video String */
110 #define ASN1_IA5STR 22 /* IA5 String */
111 #define ASN1_UNITIM 23 /* Universal Time */
112 #define ASN1_GENTIM 24 /* General Time */
113 #define ASN1_GRASTR 25 /* Graphical String */
114 #define ASN1_VISSTR 26 /* Visible String */
115 #define ASN1_GENSTR 27 /* General String */
116
117 /* Primitive / Constructed methods*/
118 #define ASN1_PRI 0 /* Primitive */
119 #define ASN1_CON 1 /* Constructed */
120
121 /*
122 * Error codes.
123 */
124 #define ASN1_ERR_NOERROR 0
125 #define ASN1_ERR_DEC_EMPTY 2
126 #define ASN1_ERR_DEC_EOC_MISMATCH 3
127 #define ASN1_ERR_DEC_LENGTH_MISMATCH 4
128 #define ASN1_ERR_DEC_BADVALUE 5
129
130 /*
131 * ASN.1 context.
132 */
133 struct asn1_ctx
134 {
135 int error; /* Error condition */
136 unsigned char *pointer; /* Octet just to be decoded */
137 unsigned char *begin; /* First octet */
138 unsigned char *end; /* Octet after last octet */
139 };
140
141 /*
142 * Octet string (not null terminated)
143 */
144 struct asn1_octstr
145 {
146 unsigned char *data;
147 unsigned int len;
148 };
149
150 static void asn1_open(struct asn1_ctx *ctx,
151 unsigned char *buf,
152 unsigned int len)
153 {
154 ctx->begin = buf;
155 ctx->end = buf + len;
156 ctx->pointer = buf;
157 ctx->error = ASN1_ERR_NOERROR;
158 }
159
160 static unsigned char asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
161 {
162 if (ctx->pointer >= ctx->end) {
163 ctx->error = ASN1_ERR_DEC_EMPTY;
164 return 0;
165 }
166 *ch = *(ctx->pointer)++;
167 return 1;
168 }
169
170 static unsigned char asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
171 {
172 unsigned char ch;
173
174 *tag = 0;
175
176 do
177 {
178 if (!asn1_octet_decode(ctx, &ch))
179 return 0;
180 *tag <<= 7;
181 *tag |= ch & 0x7F;
182 } while ((ch & 0x80) == 0x80);
183 return 1;
184 }
185
186 static unsigned char asn1_id_decode(struct asn1_ctx *ctx,
187 unsigned int *cls,
188 unsigned int *con,
189 unsigned int *tag)
190 {
191 unsigned char ch;
192
193 if (!asn1_octet_decode(ctx, &ch))
194 return 0;
195
196 *cls = (ch & 0xC0) >> 6;
197 *con = (ch & 0x20) >> 5;
198 *tag = (ch & 0x1F);
199
200 if (*tag == 0x1F) {
201 if (!asn1_tag_decode(ctx, tag))
202 return 0;
203 }
204 return 1;
205 }
206
207 static unsigned char asn1_length_decode(struct asn1_ctx *ctx,
208 unsigned int *def,
209 unsigned int *len)
210 {
211 unsigned char ch, cnt;
212
213 if (!asn1_octet_decode(ctx, &ch))
214 return 0;
215
216 if (ch == 0x80)
217 *def = 0;
218 else {
219 *def = 1;
220
221 if (ch < 0x80)
222 *len = ch;
223 else {
224 cnt = ch & 0x7F;
225 *len = 0;
226
227 while (cnt > 0) {
228 if (!asn1_octet_decode(ctx, &ch))
229 return 0;
230 *len <<= 8;
231 *len |= ch;
232 cnt--;
233 }
234 }
235 }
236
237 /* don't trust len bigger than ctx buffer */
238 if (*len > ctx->end - ctx->pointer)
239 return 0;
240
241 return 1;
242 }
243
244 static unsigned char asn1_header_decode(struct asn1_ctx *ctx,
245 unsigned char **eoc,
246 unsigned int *cls,
247 unsigned int *con,
248 unsigned int *tag)
249 {
250 unsigned int def, len;
251
252 if (!asn1_id_decode(ctx, cls, con, tag))
253 return 0;
254
255 def = len = 0;
256 if (!asn1_length_decode(ctx, &def, &len))
257 return 0;
258
259 /* primitive shall be definite, indefinite shall be constructed */
260 if (*con == ASN1_PRI && !def)
261 return 0;
262
263 if (def)
264 *eoc = ctx->pointer + len;
265 else
266 *eoc = NULL;
267 return 1;
268 }
269
270 static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
271 {
272 unsigned char ch;
273
274 if (eoc == NULL) {
275 if (!asn1_octet_decode(ctx, &ch))
276 return 0;
277
278 if (ch != 0x00) {
279 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
280 return 0;
281 }
282
283 if (!asn1_octet_decode(ctx, &ch))
284 return 0;
285
286 if (ch != 0x00) {
287 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
288 return 0;
289 }
290 return 1;
291 } else {
292 if (ctx->pointer != eoc) {
293 ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
294 return 0;
295 }
296 return 1;
297 }
298 }
299
300 static unsigned char asn1_null_decode(struct asn1_ctx *ctx, unsigned char *eoc)
301 {
302 ctx->pointer = eoc;
303 return 1;
304 }
305
306 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
307 unsigned char *eoc,
308 long *integer)
309 {
310 unsigned char ch;
311 unsigned int len;
312
313 if (!asn1_octet_decode(ctx, &ch))
314 return 0;
315
316 *integer = (signed char) ch;
317 len = 1;
318
319 while (ctx->pointer < eoc) {
320 if (++len > sizeof (long)) {
321 ctx->error = ASN1_ERR_DEC_BADVALUE;
322 return 0;
323 }
324
325 if (!asn1_octet_decode(ctx, &ch))
326 return 0;
327
328 *integer <<= 8;
329 *integer |= ch;
330 }
331 return 1;
332 }
333
334 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
335 unsigned char *eoc,
336 unsigned int *integer)
337 {
338 unsigned char ch;
339 unsigned int len;
340
341 if (!asn1_octet_decode(ctx, &ch))
342 return 0;
343
344 *integer = ch;
345 if (ch == 0) len = 0;
346 else len = 1;
347
348 while (ctx->pointer < eoc) {
349 if (++len > sizeof (unsigned int)) {
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 asn1_ulong_decode(struct asn1_ctx *ctx,
364 unsigned char *eoc,
365 unsigned long *integer)
366 {
367 unsigned char ch;
368 unsigned int len;
369
370 if (!asn1_octet_decode(ctx, &ch))
371 return 0;
372
373 *integer = ch;
374 if (ch == 0) len = 0;
375 else len = 1;
376
377 while (ctx->pointer < eoc) {
378 if (++len > sizeof (unsigned long)) {
379 ctx->error = ASN1_ERR_DEC_BADVALUE;
380 return 0;
381 }
382
383 if (!asn1_octet_decode(ctx, &ch))
384 return 0;
385
386 *integer <<= 8;
387 *integer |= ch;
388 }
389 return 1;
390 }
391
392 static unsigned char asn1_octets_decode(struct asn1_ctx *ctx,
393 unsigned char *eoc,
394 unsigned char **octets,
395 unsigned int *len)
396 {
397 unsigned char *ptr;
398
399 *len = 0;
400
401 *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
402 if (*octets == NULL) {
403 if (net_ratelimit())
404 pr_notice("OOM in bsalg (%d)\n", __LINE__);
405 return 0;
406 }
407
408 ptr = *octets;
409 while (ctx->pointer < eoc) {
410 if (!asn1_octet_decode(ctx, (unsigned char *)ptr++)) {
411 kfree(*octets);
412 *octets = NULL;
413 return 0;
414 }
415 (*len)++;
416 }
417 return 1;
418 }
419
420 static unsigned char asn1_subid_decode(struct asn1_ctx *ctx,
421 unsigned long *subid)
422 {
423 unsigned char ch;
424
425 *subid = 0;
426
427 do {
428 if (!asn1_octet_decode(ctx, &ch))
429 return 0;
430
431 *subid <<= 7;
432 *subid |= ch & 0x7F;
433 } while ((ch & 0x80) == 0x80);
434 return 1;
435 }
436
437 static unsigned char asn1_oid_decode(struct asn1_ctx *ctx,
438 unsigned char *eoc,
439 unsigned long **oid,
440 unsigned int *len)
441 {
442 unsigned long subid;
443 unsigned long *optr;
444 size_t size;
445
446 size = eoc - ctx->pointer + 1;
447
448 /* first subid actually encodes first two subids */
449 if (size < 2 || size > ULONG_MAX/sizeof(unsigned long))
450 return 0;
451
452 *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
453 if (*oid == NULL) {
454 if (net_ratelimit())
455 pr_notice("OOM in bsalg (%d)\n", __LINE__);
456 return 0;
457 }
458
459 optr = *oid;
460
461 if (!asn1_subid_decode(ctx, &subid)) {
462 kfree(*oid);
463 *oid = NULL;
464 return 0;
465 }
466
467 if (subid < 40) {
468 optr [0] = 0;
469 optr [1] = subid;
470 } else if (subid < 80) {
471 optr [0] = 1;
472 optr [1] = subid - 40;
473 } else {
474 optr [0] = 2;
475 optr [1] = subid - 80;
476 }
477
478 *len = 2;
479 optr += 2;
480
481 while (ctx->pointer < eoc) {
482 if (++(*len) > size) {
483 ctx->error = ASN1_ERR_DEC_BADVALUE;
484 kfree(*oid);
485 *oid = NULL;
486 return 0;
487 }
488
489 if (!asn1_subid_decode(ctx, optr++)) {
490 kfree(*oid);
491 *oid = NULL;
492 return 0;
493 }
494 }
495 return 1;
496 }
497
498 /*****************************************************************************
499 *
500 * SNMP decoding routines (gxsnmp author Dirk Wisse)
501 *
502 *****************************************************************************/
503
504 /* SNMP Versions */
505 #define SNMP_V1 0
506 #define SNMP_V2C 1
507 #define SNMP_V2 2
508 #define SNMP_V3 3
509
510 /* Default Sizes */
511 #define SNMP_SIZE_COMM 256
512 #define SNMP_SIZE_OBJECTID 128
513 #define SNMP_SIZE_BUFCHR 256
514 #define SNMP_SIZE_BUFINT 128
515 #define SNMP_SIZE_SMALLOBJECTID 16
516
517 /* Requests */
518 #define SNMP_PDU_GET 0
519 #define SNMP_PDU_NEXT 1
520 #define SNMP_PDU_RESPONSE 2
521 #define SNMP_PDU_SET 3
522 #define SNMP_PDU_TRAP1 4
523 #define SNMP_PDU_BULK 5
524 #define SNMP_PDU_INFORM 6
525 #define SNMP_PDU_TRAP2 7
526
527 /* Errors */
528 #define SNMP_NOERROR 0
529 #define SNMP_TOOBIG 1
530 #define SNMP_NOSUCHNAME 2
531 #define SNMP_BADVALUE 3
532 #define SNMP_READONLY 4
533 #define SNMP_GENERROR 5
534 #define SNMP_NOACCESS 6
535 #define SNMP_WRONGTYPE 7
536 #define SNMP_WRONGLENGTH 8
537 #define SNMP_WRONGENCODING 9
538 #define SNMP_WRONGVALUE 10
539 #define SNMP_NOCREATION 11
540 #define SNMP_INCONSISTENTVALUE 12
541 #define SNMP_RESOURCEUNAVAILABLE 13
542 #define SNMP_COMMITFAILED 14
543 #define SNMP_UNDOFAILED 15
544 #define SNMP_AUTHORIZATIONERROR 16
545 #define SNMP_NOTWRITABLE 17
546 #define SNMP_INCONSISTENTNAME 18
547
548 /* General SNMP V1 Traps */
549 #define SNMP_TRAP_COLDSTART 0
550 #define SNMP_TRAP_WARMSTART 1
551 #define SNMP_TRAP_LINKDOWN 2
552 #define SNMP_TRAP_LINKUP 3
553 #define SNMP_TRAP_AUTFAILURE 4
554 #define SNMP_TRAP_EQPNEIGHBORLOSS 5
555 #define SNMP_TRAP_ENTSPECIFIC 6
556
557 /* SNMPv1 Types */
558 #define SNMP_NULL 0
559 #define SNMP_INTEGER 1 /* l */
560 #define SNMP_OCTETSTR 2 /* c */
561 #define SNMP_DISPLAYSTR 2 /* c */
562 #define SNMP_OBJECTID 3 /* ul */
563 #define SNMP_IPADDR 4 /* uc */
564 #define SNMP_COUNTER 5 /* ul */
565 #define SNMP_GAUGE 6 /* ul */
566 #define SNMP_TIMETICKS 7 /* ul */
567 #define SNMP_OPAQUE 8 /* c */
568
569 /* Additional SNMPv2 Types */
570 #define SNMP_UINTEGER 5 /* ul */
571 #define SNMP_BITSTR 9 /* uc */
572 #define SNMP_NSAP 10 /* uc */
573 #define SNMP_COUNTER64 11 /* ul */
574 #define SNMP_NOSUCHOBJECT 12
575 #define SNMP_NOSUCHINSTANCE 13
576 #define SNMP_ENDOFMIBVIEW 14
577
578 union snmp_syntax
579 {
580 unsigned char uc[0]; /* 8 bit unsigned */
581 char c[0]; /* 8 bit signed */
582 unsigned long ul[0]; /* 32 bit unsigned */
583 long l[0]; /* 32 bit signed */
584 };
585
586 struct snmp_object
587 {
588 unsigned long *id;
589 unsigned int id_len;
590 unsigned short type;
591 unsigned int syntax_len;
592 union snmp_syntax syntax;
593 };
594
595 struct snmp_request
596 {
597 unsigned long id;
598 unsigned int error_status;
599 unsigned int error_index;
600 };
601
602 struct snmp_v1_trap
603 {
604 unsigned long *id;
605 unsigned int id_len;
606 unsigned long ip_address; /* pointer */
607 unsigned int general;
608 unsigned int specific;
609 unsigned long time;
610 };
611
612 /* SNMP types */
613 #define SNMP_IPA 0
614 #define SNMP_CNT 1
615 #define SNMP_GGE 2
616 #define SNMP_TIT 3
617 #define SNMP_OPQ 4
618 #define SNMP_C64 6
619
620 /* SNMP errors */
621 #define SERR_NSO 0
622 #define SERR_NSI 1
623 #define SERR_EOM 2
624
625 static inline void mangle_address(unsigned char *begin,
626 unsigned char *addr,
627 const struct oct1_map *map,
628 __sum16 *check);
629 struct snmp_cnv
630 {
631 unsigned int class;
632 unsigned int tag;
633 int syntax;
634 };
635
636 static const struct snmp_cnv snmp_conv[] = {
637 {ASN1_UNI, ASN1_NUL, SNMP_NULL},
638 {ASN1_UNI, ASN1_INT, SNMP_INTEGER},
639 {ASN1_UNI, ASN1_OTS, SNMP_OCTETSTR},
640 {ASN1_UNI, ASN1_OTS, SNMP_DISPLAYSTR},
641 {ASN1_UNI, ASN1_OJI, SNMP_OBJECTID},
642 {ASN1_APL, SNMP_IPA, SNMP_IPADDR},
643 {ASN1_APL, SNMP_CNT, SNMP_COUNTER}, /* Counter32 */
644 {ASN1_APL, SNMP_GGE, SNMP_GAUGE}, /* Gauge32 == Unsigned32 */
645 {ASN1_APL, SNMP_TIT, SNMP_TIMETICKS},
646 {ASN1_APL, SNMP_OPQ, SNMP_OPAQUE},
647
648 /* SNMPv2 data types and errors */
649 {ASN1_UNI, ASN1_BTS, SNMP_BITSTR},
650 {ASN1_APL, SNMP_C64, SNMP_COUNTER64},
651 {ASN1_CTX, SERR_NSO, SNMP_NOSUCHOBJECT},
652 {ASN1_CTX, SERR_NSI, SNMP_NOSUCHINSTANCE},
653 {ASN1_CTX, SERR_EOM, SNMP_ENDOFMIBVIEW},
654 {0, 0, -1}
655 };
656
657 static unsigned char snmp_tag_cls2syntax(unsigned int tag,
658 unsigned int cls,
659 unsigned short *syntax)
660 {
661 const struct snmp_cnv *cnv;
662
663 cnv = snmp_conv;
664
665 while (cnv->syntax != -1) {
666 if (cnv->tag == tag && cnv->class == cls) {
667 *syntax = cnv->syntax;
668 return 1;
669 }
670 cnv++;
671 }
672 return 0;
673 }
674
675 static unsigned char snmp_object_decode(struct asn1_ctx *ctx,
676 struct snmp_object **obj)
677 {
678 unsigned int cls, con, tag, len, idlen;
679 unsigned short type;
680 unsigned char *eoc, *end, *p;
681 unsigned long *lp, *id;
682 unsigned long ul;
683 long l;
684
685 *obj = NULL;
686 id = NULL;
687
688 if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag))
689 return 0;
690
691 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
692 return 0;
693
694 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
695 return 0;
696
697 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
698 return 0;
699
700 if (!asn1_oid_decode(ctx, end, &id, &idlen))
701 return 0;
702
703 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) {
704 kfree(id);
705 return 0;
706 }
707
708 if (con != ASN1_PRI) {
709 kfree(id);
710 return 0;
711 }
712
713 type = 0;
714 if (!snmp_tag_cls2syntax(tag, cls, &type)) {
715 kfree(id);
716 return 0;
717 }
718
719 l = 0;
720 switch (type) {
721 case SNMP_INTEGER:
722 len = sizeof(long);
723 if (!asn1_long_decode(ctx, end, &l)) {
724 kfree(id);
725 return 0;
726 }
727 *obj = kmalloc(sizeof(struct snmp_object) + len,
728 GFP_ATOMIC);
729 if (*obj == NULL) {
730 kfree(id);
731 if (net_ratelimit())
732 pr_notice("OOM in bsalg (%d)\n", __LINE__);
733 return 0;
734 }
735 (*obj)->syntax.l[0] = l;
736 break;
737 case SNMP_OCTETSTR:
738 case SNMP_OPAQUE:
739 if (!asn1_octets_decode(ctx, end, &p, &len)) {
740 kfree(id);
741 return 0;
742 }
743 *obj = kmalloc(sizeof(struct snmp_object) + len,
744 GFP_ATOMIC);
745 if (*obj == NULL) {
746 kfree(p);
747 kfree(id);
748 if (net_ratelimit())
749 pr_notice("OOM in bsalg (%d)\n", __LINE__);
750 return 0;
751 }
752 memcpy((*obj)->syntax.c, p, len);
753 kfree(p);
754 break;
755 case SNMP_NULL:
756 case SNMP_NOSUCHOBJECT:
757 case SNMP_NOSUCHINSTANCE:
758 case SNMP_ENDOFMIBVIEW:
759 len = 0;
760 *obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
761 if (*obj == NULL) {
762 kfree(id);
763 if (net_ratelimit())
764 pr_notice("OOM in bsalg (%d)\n", __LINE__);
765 return 0;
766 }
767 if (!asn1_null_decode(ctx, end)) {
768 kfree(id);
769 kfree(*obj);
770 *obj = NULL;
771 return 0;
772 }
773 break;
774 case SNMP_OBJECTID:
775 if (!asn1_oid_decode(ctx, end, (unsigned long **)&lp, &len)) {
776 kfree(id);
777 return 0;
778 }
779 len *= sizeof(unsigned long);
780 *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
781 if (*obj == NULL) {
782 kfree(lp);
783 kfree(id);
784 if (net_ratelimit())
785 pr_notice("OOM in bsalg (%d)\n", __LINE__);
786 return 0;
787 }
788 memcpy((*obj)->syntax.ul, lp, len);
789 kfree(lp);
790 break;
791 case SNMP_IPADDR:
792 if (!asn1_octets_decode(ctx, end, &p, &len)) {
793 kfree(id);
794 return 0;
795 }
796 if (len != 4) {
797 kfree(p);
798 kfree(id);
799 return 0;
800 }
801 *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
802 if (*obj == NULL) {
803 kfree(p);
804 kfree(id);
805 if (net_ratelimit())
806 pr_notice("OOM in bsalg (%d)\n", __LINE__);
807 return 0;
808 }
809 memcpy((*obj)->syntax.uc, p, len);
810 kfree(p);
811 break;
812 case SNMP_COUNTER:
813 case SNMP_GAUGE:
814 case SNMP_TIMETICKS:
815 len = sizeof(unsigned long);
816 if (!asn1_ulong_decode(ctx, end, &ul)) {
817 kfree(id);
818 return 0;
819 }
820 *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
821 if (*obj == NULL) {
822 kfree(id);
823 if (net_ratelimit())
824 pr_notice("OOM in bsalg (%d)\n", __LINE__);
825 return 0;
826 }
827 (*obj)->syntax.ul[0] = ul;
828 break;
829 default:
830 kfree(id);
831 return 0;
832 }
833
834 (*obj)->syntax_len = len;
835 (*obj)->type = type;
836 (*obj)->id = id;
837 (*obj)->id_len = idlen;
838
839 if (!asn1_eoc_decode(ctx, eoc)) {
840 kfree(id);
841 kfree(*obj);
842 *obj = NULL;
843 return 0;
844 }
845 return 1;
846 }
847
848 static unsigned char snmp_request_decode(struct asn1_ctx *ctx,
849 struct snmp_request *request)
850 {
851 unsigned int cls, con, tag;
852 unsigned char *end;
853
854 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
855 return 0;
856
857 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
858 return 0;
859
860 if (!asn1_ulong_decode(ctx, end, &request->id))
861 return 0;
862
863 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
864 return 0;
865
866 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
867 return 0;
868
869 if (!asn1_uint_decode(ctx, end, &request->error_status))
870 return 0;
871
872 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
873 return 0;
874
875 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
876 return 0;
877
878 if (!asn1_uint_decode(ctx, end, &request->error_index))
879 return 0;
880
881 return 1;
882 }
883
884 /*
885 * Fast checksum update for possibly oddly-aligned UDP byte, from the
886 * code example in the draft.
887 */
888 static void fast_csum(__sum16 *csum,
889 const unsigned char *optr,
890 const unsigned char *nptr,
891 int offset)
892 {
893 unsigned char s[4];
894
895 if (offset & 1) {
896 s[0] = ~0;
897 s[1] = ~*optr;
898 s[2] = 0;
899 s[3] = *nptr;
900 } else {
901 s[0] = ~*optr;
902 s[1] = ~0;
903 s[2] = *nptr;
904 s[3] = 0;
905 }
906
907 *csum = csum_fold(csum_partial(s, 4, ~csum_unfold(*csum)));
908 }
909
910 /*
911 * Mangle IP address.
912 * - begin points to the start of the snmp messgae
913 * - addr points to the start of the address
914 */
915 static inline void mangle_address(unsigned char *begin,
916 unsigned char *addr,
917 const struct oct1_map *map,
918 __sum16 *check)
919 {
920 if (map->from == NOCT1(addr)) {
921 u_int32_t old;
922
923 if (debug)
924 memcpy(&old, addr, sizeof(old));
925
926 *addr = map->to;
927
928 /* Update UDP checksum if being used */
929 if (*check) {
930 fast_csum(check,
931 &map->from, &map->to, addr - begin);
932
933 }
934
935 if (debug)
936 printk(KERN_DEBUG "bsalg: mapped %pI4 to %pI4\n",
937 &old, addr);
938 }
939 }
940
941 static unsigned char snmp_trap_decode(struct asn1_ctx *ctx,
942 struct snmp_v1_trap *trap,
943 const struct oct1_map *map,
944 __sum16 *check)
945 {
946 unsigned int cls, con, tag, len;
947 unsigned char *end;
948
949 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
950 return 0;
951
952 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
953 return 0;
954
955 if (!asn1_oid_decode(ctx, end, &trap->id, &trap->id_len))
956 return 0;
957
958 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
959 goto err_id_free;
960
961 if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_IPA) ||
962 (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_OTS)))
963 goto err_id_free;
964
965 if (!asn1_octets_decode(ctx, end, (unsigned char **)&trap->ip_address, &len))
966 goto err_id_free;
967
968 /* IPv4 only */
969 if (len != 4)
970 goto err_addr_free;
971
972 mangle_address(ctx->begin, ctx->pointer - 4, map, check);
973
974 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
975 goto err_addr_free;
976
977 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
978 goto err_addr_free;
979
980 if (!asn1_uint_decode(ctx, end, &trap->general))
981 goto err_addr_free;
982
983 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
984 goto err_addr_free;
985
986 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
987 goto err_addr_free;
988
989 if (!asn1_uint_decode(ctx, end, &trap->specific))
990 goto err_addr_free;
991
992 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
993 goto err_addr_free;
994
995 if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_TIT) ||
996 (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_INT)))
997 goto err_addr_free;
998
999 if (!asn1_ulong_decode(ctx, end, &trap->time))
1000 goto err_addr_free;
1001
1002 return 1;
1003
1004 err_addr_free:
1005 kfree((unsigned long *)trap->ip_address);
1006
1007 err_id_free:
1008 kfree(trap->id);
1009
1010 return 0;
1011 }
1012
1013 /*****************************************************************************
1014 *
1015 * Misc. routines
1016 *
1017 *****************************************************************************/
1018
1019 static void hex_dump(const unsigned char *buf, size_t len)
1020 {
1021 size_t i;
1022
1023 for (i = 0; i < len; i++) {
1024 if (i && !(i % 16))
1025 printk("\n");
1026 printk("%02x ", *(buf + i));
1027 }
1028 printk("\n");
1029 }
1030
1031 /*
1032 * Parse and mangle SNMP message according to mapping.
1033 * (And this is the fucking 'basic' method).
1034 */
1035 static int snmp_parse_mangle(unsigned char *msg,
1036 u_int16_t len,
1037 const struct oct1_map *map,
1038 __sum16 *check)
1039 {
1040 unsigned char *eoc, *end;
1041 unsigned int cls, con, tag, vers, pdutype;
1042 struct asn1_ctx ctx;
1043 struct asn1_octstr comm;
1044 struct snmp_object *obj;
1045
1046 if (debug > 1)
1047 hex_dump(msg, len);
1048
1049 asn1_open(&ctx, msg, len);
1050
1051 /*
1052 * Start of SNMP message.
1053 */
1054 if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
1055 return 0;
1056 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
1057 return 0;
1058
1059 /*
1060 * Version 1 or 2 handled.
1061 */
1062 if (!asn1_header_decode(&ctx, &end, &cls, &con, &tag))
1063 return 0;
1064 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
1065 return 0;
1066 if (!asn1_uint_decode (&ctx, end, &vers))
1067 return 0;
1068 if (debug > 1)
1069 printk(KERN_DEBUG "bsalg: snmp version: %u\n", vers + 1);
1070 if (vers > 1)
1071 return 1;
1072
1073 /*
1074 * Community.
1075 */
1076 if (!asn1_header_decode (&ctx, &end, &cls, &con, &tag))
1077 return 0;
1078 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OTS)
1079 return 0;
1080 if (!asn1_octets_decode(&ctx, end, &comm.data, &comm.len))
1081 return 0;
1082 if (debug > 1) {
1083 unsigned int i;
1084
1085 printk(KERN_DEBUG "bsalg: community: ");
1086 for (i = 0; i < comm.len; i++)
1087 printk("%c", comm.data[i]);
1088 printk("\n");
1089 }
1090 kfree(comm.data);
1091
1092 /*
1093 * PDU type
1094 */
1095 if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &pdutype))
1096 return 0;
1097 if (cls != ASN1_CTX || con != ASN1_CON)
1098 return 0;
1099 if (debug > 1) {
1100 static const unsigned char *const pdus[] = {
1101 [SNMP_PDU_GET] = "get",
1102 [SNMP_PDU_NEXT] = "get-next",
1103 [SNMP_PDU_RESPONSE] = "response",
1104 [SNMP_PDU_SET] = "set",
1105 [SNMP_PDU_TRAP1] = "trapv1",
1106 [SNMP_PDU_BULK] = "bulk",
1107 [SNMP_PDU_INFORM] = "inform",
1108 [SNMP_PDU_TRAP2] = "trapv2"
1109 };
1110
1111 if (pdutype > SNMP_PDU_TRAP2)
1112 printk(KERN_DEBUG "bsalg: bad pdu type %u\n", pdutype);
1113 else
1114 printk(KERN_DEBUG "bsalg: pdu: %s\n", pdus[pdutype]);
1115 }
1116 if (pdutype != SNMP_PDU_RESPONSE &&
1117 pdutype != SNMP_PDU_TRAP1 && pdutype != SNMP_PDU_TRAP2)
1118 return 1;
1119
1120 /*
1121 * Request header or v1 trap
1122 */
1123 if (pdutype == SNMP_PDU_TRAP1) {
1124 struct snmp_v1_trap trap;
1125 unsigned char ret = snmp_trap_decode(&ctx, &trap, map, check);
1126
1127 if (ret) {
1128 kfree(trap.id);
1129 kfree((unsigned long *)trap.ip_address);
1130 } else
1131 return ret;
1132
1133 } else {
1134 struct snmp_request req;
1135
1136 if (!snmp_request_decode(&ctx, &req))
1137 return 0;
1138
1139 if (debug > 1)
1140 printk(KERN_DEBUG "bsalg: request: id=0x%lx error_status=%u "
1141 "error_index=%u\n", req.id, req.error_status,
1142 req.error_index);
1143 }
1144
1145 /*
1146 * Loop through objects, look for IP addresses to mangle.
1147 */
1148 if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
1149 return 0;
1150
1151 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
1152 return 0;
1153
1154 while (!asn1_eoc_decode(&ctx, eoc)) {
1155 unsigned int i;
1156
1157 if (!snmp_object_decode(&ctx, &obj)) {
1158 if (obj) {
1159 kfree(obj->id);
1160 kfree(obj);
1161 }
1162 return 0;
1163 }
1164
1165 if (debug > 1) {
1166 printk(KERN_DEBUG "bsalg: object: ");
1167 for (i = 0; i < obj->id_len; i++) {
1168 if (i > 0)
1169 printk(".");
1170 printk("%lu", obj->id[i]);
1171 }
1172 printk(": type=%u\n", obj->type);
1173
1174 }
1175
1176 if (obj->type == SNMP_IPADDR)
1177 mangle_address(ctx.begin, ctx.pointer - 4 , map, check);
1178
1179 kfree(obj->id);
1180 kfree(obj);
1181 }
1182
1183 if (!asn1_eoc_decode(&ctx, eoc))
1184 return 0;
1185
1186 return 1;
1187 }
1188
1189 /*****************************************************************************
1190 *
1191 * NAT routines.
1192 *
1193 *****************************************************************************/
1194
1195 /*
1196 * SNMP translation routine.
1197 */
1198 static int snmp_translate(struct nf_conn *ct,
1199 enum ip_conntrack_info ctinfo,
1200 struct sk_buff *skb)
1201 {
1202 struct iphdr *iph = ip_hdr(skb);
1203 struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
1204 u_int16_t udplen = ntohs(udph->len);
1205 u_int16_t paylen = udplen - sizeof(struct udphdr);
1206 int dir = CTINFO2DIR(ctinfo);
1207 struct oct1_map map;
1208
1209 /*
1210 * Determine mappping for application layer addresses based
1211 * on NAT manipulations for the packet.
1212 */
1213 if (dir == IP_CT_DIR_ORIGINAL) {
1214 /* SNAT traps */
1215 map.from = NOCT1(&ct->tuplehash[dir].tuple.src.u3.ip);
1216 map.to = NOCT1(&ct->tuplehash[!dir].tuple.dst.u3.ip);
1217 } else {
1218 /* DNAT replies */
1219 map.from = NOCT1(&ct->tuplehash[dir].tuple.src.u3.ip);
1220 map.to = NOCT1(&ct->tuplehash[!dir].tuple.dst.u3.ip);
1221 }
1222
1223 if (map.from == map.to)
1224 return NF_ACCEPT;
1225
1226 if (!snmp_parse_mangle((unsigned char *)udph + sizeof(struct udphdr),
1227 paylen, &map, &udph->check)) {
1228 if (net_ratelimit())
1229 printk(KERN_WARNING "bsalg: parser failed\n");
1230 return NF_DROP;
1231 }
1232 return NF_ACCEPT;
1233 }
1234
1235 /* We don't actually set up expectations, just adjust internal IP
1236 * addresses if this is being NATted */
1237 static int help(struct sk_buff *skb, unsigned int protoff,
1238 struct nf_conn *ct,
1239 enum ip_conntrack_info ctinfo)
1240 {
1241 int dir = CTINFO2DIR(ctinfo);
1242 unsigned int ret;
1243 const struct iphdr *iph = ip_hdr(skb);
1244 const struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
1245
1246 /* SNMP replies and originating SNMP traps get mangled */
1247 if (udph->source == htons(SNMP_PORT) && dir != IP_CT_DIR_REPLY)
1248 return NF_ACCEPT;
1249 if (udph->dest == htons(SNMP_TRAP_PORT) && dir != IP_CT_DIR_ORIGINAL)
1250 return NF_ACCEPT;
1251
1252 /* No NAT? */
1253 if (!(ct->status & IPS_NAT_MASK))
1254 return NF_ACCEPT;
1255
1256 /*
1257 * Make sure the packet length is ok. So far, we were only guaranteed
1258 * to have a valid length IP header plus 8 bytes, which means we have
1259 * enough room for a UDP header. Just verify the UDP length field so we
1260 * can mess around with the payload.
1261 */
1262 if (ntohs(udph->len) != skb->len - (iph->ihl << 2)) {
1263 if (net_ratelimit())
1264 printk(KERN_WARNING "SNMP: dropping malformed packet src=%pI4 dst=%pI4\n",
1265 &iph->saddr, &iph->daddr);
1266 return NF_DROP;
1267 }
1268
1269 if (!skb_make_writable(skb, skb->len))
1270 return NF_DROP;
1271
1272 spin_lock_bh(&snmp_lock);
1273 ret = snmp_translate(ct, ctinfo, skb);
1274 spin_unlock_bh(&snmp_lock);
1275 return ret;
1276 }
1277
1278 static const struct nf_conntrack_expect_policy snmp_exp_policy = {
1279 .max_expected = 0,
1280 .timeout = 180,
1281 };
1282
1283 static struct nf_conntrack_helper snmp_helper __read_mostly = {
1284 .me = THIS_MODULE,
1285 .help = help,
1286 .expect_policy = &snmp_exp_policy,
1287 .name = "snmp",
1288 .tuple.src.l3num = AF_INET,
1289 .tuple.src.u.udp.port = cpu_to_be16(SNMP_PORT),
1290 .tuple.dst.protonum = IPPROTO_UDP,
1291 };
1292
1293 static struct nf_conntrack_helper snmp_trap_helper __read_mostly = {
1294 .me = THIS_MODULE,
1295 .help = help,
1296 .expect_policy = &snmp_exp_policy,
1297 .name = "snmp_trap",
1298 .tuple.src.l3num = AF_INET,
1299 .tuple.src.u.udp.port = cpu_to_be16(SNMP_TRAP_PORT),
1300 .tuple.dst.protonum = IPPROTO_UDP,
1301 };
1302
1303 /*****************************************************************************
1304 *
1305 * Module stuff.
1306 *
1307 *****************************************************************************/
1308
1309 static int __init nf_nat_snmp_basic_init(void)
1310 {
1311 int ret = 0;
1312
1313 ret = nf_conntrack_helper_register(&snmp_helper);
1314 if (ret < 0)
1315 return ret;
1316 ret = nf_conntrack_helper_register(&snmp_trap_helper);
1317 if (ret < 0) {
1318 nf_conntrack_helper_unregister(&snmp_helper);
1319 return ret;
1320 }
1321 return ret;
1322 }
1323
1324 static void __exit nf_nat_snmp_basic_fini(void)
1325 {
1326 nf_conntrack_helper_unregister(&snmp_helper);
1327 nf_conntrack_helper_unregister(&snmp_trap_helper);
1328 }
1329
1330 module_init(nf_nat_snmp_basic_init);
1331 module_exit(nf_nat_snmp_basic_fini);
1332
1333 module_param(debug, int, 0600);
Tomato firmware and modifications.