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Linux-2.6.12-rc2
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / net / ipv4 / netfilter / ip_nat_snmp_basic.c
blob2a48b6e635aef35193fb3b70babe78d17c03519d
1 /*
2 * ip_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 * Updates:
43 * 2000-08-06: Convert to new helper API (Harald Welte).
44 *
45 */
46 #include <linux/config.h>
47 #include <linux/module.h>
48 #include <linux/types.h>
49 #include <linux/kernel.h>
50 #include <linux/moduleparam.h>
51 #include <linux/netfilter_ipv4.h>
52 #include <linux/netfilter_ipv4/ip_nat.h>
53 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
54 #include <linux/netfilter_ipv4/ip_nat_helper.h>
55 #include <linux/ip.h>
56 #include <net/checksum.h>
57 #include <net/udp.h>
58 #include <asm/uaccess.h>
59
60 MODULE_LICENSE("GPL");
61 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
62 MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway");
63
64 #define SNMP_PORT 161
65 #define SNMP_TRAP_PORT 162
66 #define NOCT1(n) (u_int8_t )((n) & 0xff)
67
68 static int debug;
69 static DEFINE_SPINLOCK(snmp_lock);
70
71 /*
72 * Application layer address mapping mimics the NAT mapping, but
73 * only for the first octet in this case (a more flexible system
74 * can be implemented if needed).
75 */
76 struct oct1_map
77 {
78 u_int8_t from;
79 u_int8_t to;
80 };
81
82
83 /*****************************************************************************
84 *
85 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
86 *
87 *****************************************************************************/
88
89 /* Class */
90 #define ASN1_UNI 0 /* Universal */
91 #define ASN1_APL 1 /* Application */
92 #define ASN1_CTX 2 /* Context */
93 #define ASN1_PRV 3 /* Private */
94
95 /* Tag */
96 #define ASN1_EOC 0 /* End Of Contents */
97 #define ASN1_BOL 1 /* Boolean */
98 #define ASN1_INT 2 /* Integer */
99 #define ASN1_BTS 3 /* Bit String */
100 #define ASN1_OTS 4 /* Octet String */
101 #define ASN1_NUL 5 /* Null */
102 #define ASN1_OJI 6 /* Object Identifier */
103 #define ASN1_OJD 7 /* Object Description */
104 #define ASN1_EXT 8 /* External */
105 #define ASN1_SEQ 16 /* Sequence */
106 #define ASN1_SET 17 /* Set */
107 #define ASN1_NUMSTR 18 /* Numerical String */
108 #define ASN1_PRNSTR 19 /* Printable String */
109 #define ASN1_TEXSTR 20 /* Teletext String */
110 #define ASN1_VIDSTR 21 /* Video String */
111 #define ASN1_IA5STR 22 /* IA5 String */
112 #define ASN1_UNITIM 23 /* Universal Time */
113 #define ASN1_GENTIM 24 /* General Time */
114 #define ASN1_GRASTR 25 /* Graphical String */
115 #define ASN1_VISSTR 26 /* Visible String */
116 #define ASN1_GENSTR 27 /* General String */
117
118 /* Primitive / Constructed methods*/
119 #define ASN1_PRI 0 /* Primitive */
120 #define ASN1_CON 1 /* Constructed */
121
122 /*
123 * Error codes.
124 */
125 #define ASN1_ERR_NOERROR 0
126 #define ASN1_ERR_DEC_EMPTY 2
127 #define ASN1_ERR_DEC_EOC_MISMATCH 3
128 #define ASN1_ERR_DEC_LENGTH_MISMATCH 4
129 #define ASN1_ERR_DEC_BADVALUE 5
130
131 /*
132 * ASN.1 context.
133 */
134 struct asn1_ctx
135 {
136 int error; /* Error condition */
137 unsigned char *pointer; /* Octet just to be decoded */
138 unsigned char *begin; /* First octet */
139 unsigned char *end; /* Octet after last octet */
140 };
141
142 /*
143 * Octet string (not null terminated)
144 */
145 struct asn1_octstr
146 {
147 unsigned char *data;
148 unsigned int len;
149 };
150
151 static void asn1_open(struct asn1_ctx *ctx,
152 unsigned char *buf,
153 unsigned int len)
154 {
155 ctx->begin = buf;
156 ctx->end = buf + len;
157 ctx->pointer = buf;
158 ctx->error = ASN1_ERR_NOERROR;
159 }
160
161 static unsigned char asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
162 {
163 if (ctx->pointer >= ctx->end) {
164 ctx->error = ASN1_ERR_DEC_EMPTY;
165 return 0;
166 }
167 *ch = *(ctx->pointer)++;
168 return 1;
169 }
170
171 static unsigned char asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
172 {
173 unsigned char ch;
174
175 *tag = 0;
176
177 do
178 {
179 if (!asn1_octet_decode(ctx, &ch))
180 return 0;
181 *tag <<= 7;
182 *tag |= ch & 0x7F;
183 } while ((ch & 0x80) == 0x80);
184 return 1;
185 }
186
187 static unsigned char asn1_id_decode(struct asn1_ctx *ctx,
188 unsigned int *cls,
189 unsigned int *con,
190 unsigned int *tag)
191 {
192 unsigned char ch;
193
194 if (!asn1_octet_decode(ctx, &ch))
195 return 0;
196
197 *cls = (ch & 0xC0) >> 6;
198 *con = (ch & 0x20) >> 5;
199 *tag = (ch & 0x1F);
200
201 if (*tag == 0x1F) {
202 if (!asn1_tag_decode(ctx, tag))
203 return 0;
204 }
205 return 1;
206 }
207
208 static unsigned char asn1_length_decode(struct asn1_ctx *ctx,
209 unsigned int *def,
210 unsigned int *len)
211 {
212 unsigned char ch, cnt;
213
214 if (!asn1_octet_decode(ctx, &ch))
215 return 0;
216
217 if (ch == 0x80)
218 *def = 0;
219 else {
220 *def = 1;
221
222 if (ch < 0x80)
223 *len = ch;
224 else {
225 cnt = (unsigned char) (ch & 0x7F);
226 *len = 0;
227
228 while (cnt > 0) {
229 if (!asn1_octet_decode(ctx, &ch))
230 return 0;
231 *len <<= 8;
232 *len |= ch;
233 cnt--;
234 }
235 }
236 }
237 return 1;
238 }
239
240 static unsigned char asn1_header_decode(struct asn1_ctx *ctx,
241 unsigned char **eoc,
242 unsigned int *cls,
243 unsigned int *con,
244 unsigned int *tag)
245 {
246 unsigned int def, len;
247
248 if (!asn1_id_decode(ctx, cls, con, tag))
249 return 0;
250
251 if (!asn1_length_decode(ctx, &def, &len))
252 return 0;
253
254 if (def)
255 *eoc = ctx->pointer + len;
256 else
257 *eoc = NULL;
258 return 1;
259 }
260
261 static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
262 {
263 unsigned char ch;
264
265 if (eoc == 0) {
266 if (!asn1_octet_decode(ctx, &ch))
267 return 0;
268
269 if (ch != 0x00) {
270 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
271 return 0;
272 }
273
274 if (!asn1_octet_decode(ctx, &ch))
275 return 0;
276
277 if (ch != 0x00) {
278 ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
279 return 0;
280 }
281 return 1;
282 } else {
283 if (ctx->pointer != eoc) {
284 ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
285 return 0;
286 }
287 return 1;
288 }
289 }
290
291 static unsigned char asn1_null_decode(struct asn1_ctx *ctx, unsigned char *eoc)
292 {
293 ctx->pointer = eoc;
294 return 1;
295 }
296
297 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
298 unsigned char *eoc,
299 long *integer)
300 {
301 unsigned char ch;
302 unsigned int len;
303
304 if (!asn1_octet_decode(ctx, &ch))
305 return 0;
306
307 *integer = (signed char) ch;
308 len = 1;
309
310 while (ctx->pointer < eoc) {
311 if (++len > sizeof (long)) {
312 ctx->error = ASN1_ERR_DEC_BADVALUE;
313 return 0;
314 }
315
316 if (!asn1_octet_decode(ctx, &ch))
317 return 0;
318
319 *integer <<= 8;
320 *integer |= ch;
321 }
322 return 1;
323 }
324
325 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
326 unsigned char *eoc,
327 unsigned int *integer)
328 {
329 unsigned char ch;
330 unsigned int len;
331
332 if (!asn1_octet_decode(ctx, &ch))
333 return 0;
334
335 *integer = ch;
336 if (ch == 0) len = 0;
337 else len = 1;
338
339 while (ctx->pointer < eoc) {
340 if (++len > sizeof (unsigned int)) {
341 ctx->error = ASN1_ERR_DEC_BADVALUE;
342 return 0;
343 }
344
345 if (!asn1_octet_decode(ctx, &ch))
346 return 0;
347
348 *integer <<= 8;
349 *integer |= ch;
350 }
351 return 1;
352 }
353
354 static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
355 unsigned char *eoc,
356 unsigned long *integer)
357 {
358 unsigned char ch;
359 unsigned int len;
360
361 if (!asn1_octet_decode(ctx, &ch))
362 return 0;
363
364 *integer = ch;
365 if (ch == 0) len = 0;
366 else len = 1;
367
368 while (ctx->pointer < eoc) {
369 if (++len > sizeof (unsigned long)) {
370 ctx->error = ASN1_ERR_DEC_BADVALUE;
371 return 0;
372 }
373
374 if (!asn1_octet_decode(ctx, &ch))
375 return 0;
376
377 *integer <<= 8;
378 *integer |= ch;
379 }
380 return 1;
381 }
382
383 static unsigned char asn1_octets_decode(struct asn1_ctx *ctx,
384 unsigned char *eoc,
385 unsigned char **octets,
386 unsigned int *len)
387 {
388 unsigned char *ptr;
389
390 *len = 0;
391
392 *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
393 if (*octets == NULL) {
394 if (net_ratelimit())
395 printk("OOM in bsalg (%d)\n", __LINE__);
396 return 0;
397 }
398
399 ptr = *octets;
400 while (ctx->pointer < eoc) {
401 if (!asn1_octet_decode(ctx, (unsigned char *)ptr++)) {
402 kfree(*octets);
403 *octets = NULL;
404 return 0;
405 }
406 (*len)++;
407 }
408 return 1;
409 }
410
411 static unsigned char asn1_subid_decode(struct asn1_ctx *ctx,
412 unsigned long *subid)
413 {
414 unsigned char ch;
415
416 *subid = 0;
417
418 do {
419 if (!asn1_octet_decode(ctx, &ch))
420 return 0;
421
422 *subid <<= 7;
423 *subid |= ch & 0x7F;
424 } while ((ch & 0x80) == 0x80);
425 return 1;
426 }
427
428 static unsigned char asn1_oid_decode(struct asn1_ctx *ctx,
429 unsigned char *eoc,
430 unsigned long **oid,
431 unsigned int *len)
432 {
433 unsigned long subid;
434 unsigned int size;
435 unsigned long *optr;
436
437 size = eoc - ctx->pointer + 1;
438 *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
439 if (*oid == NULL) {
440 if (net_ratelimit())
441 printk("OOM in bsalg (%d)\n", __LINE__);
442 return 0;
443 }
444
445 optr = *oid;
446
447 if (!asn1_subid_decode(ctx, &subid)) {
448 kfree(*oid);
449 *oid = NULL;
450 return 0;
451 }
452
453 if (subid < 40) {
454 optr [0] = 0;
455 optr [1] = subid;
456 } else if (subid < 80) {
457 optr [0] = 1;
458 optr [1] = subid - 40;
459 } else {
460 optr [0] = 2;
461 optr [1] = subid - 80;
462 }
463
464 *len = 2;
465 optr += 2;
466
467 while (ctx->pointer < eoc) {
468 if (++(*len) > size) {
469 ctx->error = ASN1_ERR_DEC_BADVALUE;
470 kfree(*oid);
471 *oid = NULL;
472 return 0;
473 }
474
475 if (!asn1_subid_decode(ctx, optr++)) {
476 kfree(*oid);
477 *oid = NULL;
478 return 0;
479 }
480 }
481 return 1;
482 }
483
484 /*****************************************************************************
485 *
486 * SNMP decoding routines (gxsnmp author Dirk Wisse)
487 *
488 *****************************************************************************/
489
490 /* SNMP Versions */
491 #define SNMP_V1 0
492 #define SNMP_V2C 1
493 #define SNMP_V2 2
494 #define SNMP_V3 3
495
496 /* Default Sizes */
497 #define SNMP_SIZE_COMM 256
498 #define SNMP_SIZE_OBJECTID 128
499 #define SNMP_SIZE_BUFCHR 256
500 #define SNMP_SIZE_BUFINT 128
501 #define SNMP_SIZE_SMALLOBJECTID 16
502
503 /* Requests */
504 #define SNMP_PDU_GET 0
505 #define SNMP_PDU_NEXT 1
506 #define SNMP_PDU_RESPONSE 2
507 #define SNMP_PDU_SET 3
508 #define SNMP_PDU_TRAP1 4
509 #define SNMP_PDU_BULK 5
510 #define SNMP_PDU_INFORM 6
511 #define SNMP_PDU_TRAP2 7
512
513 /* Errors */
514 #define SNMP_NOERROR 0
515 #define SNMP_TOOBIG 1
516 #define SNMP_NOSUCHNAME 2
517 #define SNMP_BADVALUE 3
518 #define SNMP_READONLY 4
519 #define SNMP_GENERROR 5
520 #define SNMP_NOACCESS 6
521 #define SNMP_WRONGTYPE 7
522 #define SNMP_WRONGLENGTH 8
523 #define SNMP_WRONGENCODING 9
524 #define SNMP_WRONGVALUE 10
525 #define SNMP_NOCREATION 11
526 #define SNMP_INCONSISTENTVALUE 12
527 #define SNMP_RESOURCEUNAVAILABLE 13
528 #define SNMP_COMMITFAILED 14
529 #define SNMP_UNDOFAILED 15
530 #define SNMP_AUTHORIZATIONERROR 16
531 #define SNMP_NOTWRITABLE 17
532 #define SNMP_INCONSISTENTNAME 18
533
534 /* General SNMP V1 Traps */
535 #define SNMP_TRAP_COLDSTART 0
536 #define SNMP_TRAP_WARMSTART 1
537 #define SNMP_TRAP_LINKDOWN 2
538 #define SNMP_TRAP_LINKUP 3
539 #define SNMP_TRAP_AUTFAILURE 4
540 #define SNMP_TRAP_EQPNEIGHBORLOSS 5
541 #define SNMP_TRAP_ENTSPECIFIC 6
542
543 /* SNMPv1 Types */
544 #define SNMP_NULL 0
545 #define SNMP_INTEGER 1 /* l */
546 #define SNMP_OCTETSTR 2 /* c */
547 #define SNMP_DISPLAYSTR 2 /* c */
548 #define SNMP_OBJECTID 3 /* ul */
549 #define SNMP_IPADDR 4 /* uc */
550 #define SNMP_COUNTER 5 /* ul */
551 #define SNMP_GAUGE 6 /* ul */
552 #define SNMP_TIMETICKS 7 /* ul */
553 #define SNMP_OPAQUE 8 /* c */
554
555 /* Additional SNMPv2 Types */
556 #define SNMP_UINTEGER 5 /* ul */
557 #define SNMP_BITSTR 9 /* uc */
558 #define SNMP_NSAP 10 /* uc */
559 #define SNMP_COUNTER64 11 /* ul */
560 #define SNMP_NOSUCHOBJECT 12
561 #define SNMP_NOSUCHINSTANCE 13
562 #define SNMP_ENDOFMIBVIEW 14
563
564 union snmp_syntax
565 {
566 unsigned char uc[0]; /* 8 bit unsigned */
567 char c[0]; /* 8 bit signed */
568 unsigned long ul[0]; /* 32 bit unsigned */
569 long l[0]; /* 32 bit signed */
570 };
571
572 struct snmp_object
573 {
574 unsigned long *id;
575 unsigned int id_len;
576 unsigned short type;
577 unsigned int syntax_len;
578 union snmp_syntax syntax;
579 };
580
581 struct snmp_request
582 {
583 unsigned long id;
584 unsigned int error_status;
585 unsigned int error_index;
586 };
587
588 struct snmp_v1_trap
589 {
590 unsigned long *id;
591 unsigned int id_len;
592 unsigned long ip_address; /* pointer */
593 unsigned int general;
594 unsigned int specific;
595 unsigned long time;
596 };
597
598 /* SNMP types */
599 #define SNMP_IPA 0
600 #define SNMP_CNT 1
601 #define SNMP_GGE 2
602 #define SNMP_TIT 3
603 #define SNMP_OPQ 4
604 #define SNMP_C64 6
605
606 /* SNMP errors */
607 #define SERR_NSO 0
608 #define SERR_NSI 1
609 #define SERR_EOM 2
610
611 static inline void mangle_address(unsigned char *begin,
612 unsigned char *addr,
613 const struct oct1_map *map,
614 u_int16_t *check);
615 struct snmp_cnv
616 {
617 unsigned int class;
618 unsigned int tag;
619 int syntax;
620 };
621
622 static struct snmp_cnv snmp_conv [] =
623 {
624 {ASN1_UNI, ASN1_NUL, SNMP_NULL},
625 {ASN1_UNI, ASN1_INT, SNMP_INTEGER},
626 {ASN1_UNI, ASN1_OTS, SNMP_OCTETSTR},
627 {ASN1_UNI, ASN1_OTS, SNMP_DISPLAYSTR},
628 {ASN1_UNI, ASN1_OJI, SNMP_OBJECTID},
629 {ASN1_APL, SNMP_IPA, SNMP_IPADDR},
630 {ASN1_APL, SNMP_CNT, SNMP_COUNTER}, /* Counter32 */
631 {ASN1_APL, SNMP_GGE, SNMP_GAUGE}, /* Gauge32 == Unsigned32 */
632 {ASN1_APL, SNMP_TIT, SNMP_TIMETICKS},
633 {ASN1_APL, SNMP_OPQ, SNMP_OPAQUE},
634
635 /* SNMPv2 data types and errors */
636 {ASN1_UNI, ASN1_BTS, SNMP_BITSTR},
637 {ASN1_APL, SNMP_C64, SNMP_COUNTER64},
638 {ASN1_CTX, SERR_NSO, SNMP_NOSUCHOBJECT},
639 {ASN1_CTX, SERR_NSI, SNMP_NOSUCHINSTANCE},
640 {ASN1_CTX, SERR_EOM, SNMP_ENDOFMIBVIEW},
641 {0, 0, -1}
642 };
643
644 static unsigned char snmp_tag_cls2syntax(unsigned int tag,
645 unsigned int cls,
646 unsigned short *syntax)
647 {
648 struct snmp_cnv *cnv;
649
650 cnv = snmp_conv;
651
652 while (cnv->syntax != -1) {
653 if (cnv->tag == tag && cnv->class == cls) {
654 *syntax = cnv->syntax;
655 return 1;
656 }
657 cnv++;
658 }
659 return 0;
660 }
661
662 static unsigned char snmp_object_decode(struct asn1_ctx *ctx,
663 struct snmp_object **obj)
664 {
665 unsigned int cls, con, tag, len, idlen;
666 unsigned short type;
667 unsigned char *eoc, *end, *p;
668 unsigned long *lp, *id;
669 unsigned long ul;
670 long l;
671
672 *obj = NULL;
673 id = NULL;
674
675 if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag))
676 return 0;
677
678 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
679 return 0;
680
681 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
682 return 0;
683
684 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
685 return 0;
686
687 if (!asn1_oid_decode(ctx, end, &id, &idlen))
688 return 0;
689
690 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) {
691 kfree(id);
692 return 0;
693 }
694
695 if (con != ASN1_PRI) {
696 kfree(id);
697 return 0;
698 }
699
700 if (!snmp_tag_cls2syntax(tag, cls, &type)) {
701 kfree(id);
702 return 0;
703 }
704
705 switch (type) {
706 case SNMP_INTEGER:
707 len = sizeof(long);
708 if (!asn1_long_decode(ctx, end, &l)) {
709 kfree(id);
710 return 0;
711 }
712 *obj = kmalloc(sizeof(struct snmp_object) + len,
713 GFP_ATOMIC);
714 if (*obj == NULL) {
715 kfree(id);
716 if (net_ratelimit())
717 printk("OOM in bsalg (%d)\n", __LINE__);
718 return 0;
719 }
720 (*obj)->syntax.l[0] = l;
721 break;
722 case SNMP_OCTETSTR:
723 case SNMP_OPAQUE:
724 if (!asn1_octets_decode(ctx, end, &p, &len)) {
725 kfree(id);
726 return 0;
727 }
728 *obj = kmalloc(sizeof(struct snmp_object) + len,
729 GFP_ATOMIC);
730 if (*obj == NULL) {
731 kfree(id);
732 if (net_ratelimit())
733 printk("OOM in bsalg (%d)\n", __LINE__);
734 return 0;
735 }
736 memcpy((*obj)->syntax.c, p, len);
737 kfree(p);
738 break;
739 case SNMP_NULL:
740 case SNMP_NOSUCHOBJECT:
741 case SNMP_NOSUCHINSTANCE:
742 case SNMP_ENDOFMIBVIEW:
743 len = 0;
744 *obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
745 if (*obj == NULL) {
746 kfree(id);
747 if (net_ratelimit())
748 printk("OOM in bsalg (%d)\n", __LINE__);
749 return 0;
750 }
751 if (!asn1_null_decode(ctx, end)) {
752 kfree(id);
753 kfree(*obj);
754 *obj = NULL;
755 return 0;
756 }
757 break;
758 case SNMP_OBJECTID:
759 if (!asn1_oid_decode(ctx, end, (unsigned long **)&lp, &len)) {
760 kfree(id);
761 return 0;
762 }
763 len *= sizeof(unsigned long);
764 *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
765 if (*obj == NULL) {
766 kfree(id);
767 if (net_ratelimit())
768 printk("OOM in bsalg (%d)\n", __LINE__);
769 return 0;
770 }
771 memcpy((*obj)->syntax.ul, lp, len);
772 kfree(lp);
773 break;
774 case SNMP_IPADDR:
775 if (!asn1_octets_decode(ctx, end, &p, &len)) {
776 kfree(id);
777 return 0;
778 }
779 if (len != 4) {
780 kfree(p);
781 kfree(id);
782 return 0;
783 }
784 *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
785 if (*obj == NULL) {
786 kfree(p);
787 kfree(id);
788 if (net_ratelimit())
789 printk("OOM in bsalg (%d)\n", __LINE__);
790 return 0;
791 }
792 memcpy((*obj)->syntax.uc, p, len);
793 kfree(p);
794 break;
795 case SNMP_COUNTER:
796 case SNMP_GAUGE:
797 case SNMP_TIMETICKS:
798 len = sizeof(unsigned long);
799 if (!asn1_ulong_decode(ctx, end, &ul)) {
800 kfree(id);
801 return 0;
802 }
803 *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
804 if (*obj == NULL) {
805 kfree(id);
806 if (net_ratelimit())
807 printk("OOM in bsalg (%d)\n", __LINE__);
808 return 0;
809 }
810 (*obj)->syntax.ul[0] = ul;
811 break;
812 default:
813 kfree(id);
814 return 0;
815 }
816
817 (*obj)->syntax_len = len;
818 (*obj)->type = type;
819 (*obj)->id = id;
820 (*obj)->id_len = idlen;
821
822 if (!asn1_eoc_decode(ctx, eoc)) {
823 kfree(id);
824 kfree(*obj);
825 *obj = NULL;
826 return 0;
827 }
828 return 1;
829 }
830
831 static unsigned char snmp_request_decode(struct asn1_ctx *ctx,
832 struct snmp_request *request)
833 {
834 unsigned int cls, con, tag;
835 unsigned char *end;
836
837 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
838 return 0;
839
840 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
841 return 0;
842
843 if (!asn1_ulong_decode(ctx, end, &request->id))
844 return 0;
845
846 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
847 return 0;
848
849 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
850 return 0;
851
852 if (!asn1_uint_decode(ctx, end, &request->error_status))
853 return 0;
854
855 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
856 return 0;
857
858 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
859 return 0;
860
861 if (!asn1_uint_decode(ctx, end, &request->error_index))
862 return 0;
863
864 return 1;
865 }
866
867 /*
868 * Fast checksum update for possibly oddly-aligned UDP byte, from the
869 * code example in the draft.
870 */
871 static void fast_csum(unsigned char *csum,
872 const unsigned char *optr,
873 const unsigned char *nptr,
874 int odd)
875 {
876 long x, old, new;
877
878 x = csum[0] * 256 + csum[1];
879
880 x =~ x & 0xFFFF;
881
882 if (odd) old = optr[0] * 256;
883 else old = optr[0];
884
885 x -= old & 0xFFFF;
886 if (x <= 0) {
887 x--;
888 x &= 0xFFFF;
889 }
890
891 if (odd) new = nptr[0] * 256;
892 else new = nptr[0];
893
894 x += new & 0xFFFF;
895 if (x & 0x10000) {
896 x++;
897 x &= 0xFFFF;
898 }
899
900 x =~ x & 0xFFFF;
901 csum[0] = x / 256;
902 csum[1] = x & 0xFF;
903 }
904
905 /*
906 * Mangle IP address.
907 * - begin points to the start of the snmp messgae
908 * - addr points to the start of the address
909 */
910 static inline void mangle_address(unsigned char *begin,
911 unsigned char *addr,
912 const struct oct1_map *map,
913 u_int16_t *check)
914 {
915 if (map->from == NOCT1(*addr)) {
916 u_int32_t old;
917
918 if (debug)
919 memcpy(&old, (unsigned char *)addr, sizeof(old));
920
921 *addr = map->to;
922
923 /* Update UDP checksum if being used */
924 if (*check) {
925 unsigned char odd = !((addr - begin) % 2);
926
927 fast_csum((unsigned char *)check,
928 &map->from, &map->to, odd);
929
930 }
931
932 if (debug)
933 printk(KERN_DEBUG "bsalg: mapped %u.%u.%u.%u to "
934 "%u.%u.%u.%u\n", NIPQUAD(old), NIPQUAD(*addr));
935 }
936 }
937
938 static unsigned char snmp_trap_decode(struct asn1_ctx *ctx,
939 struct snmp_v1_trap *trap,
940 const struct oct1_map *map,
941 u_int16_t *check)
942 {
943 unsigned int cls, con, tag, len;
944 unsigned char *end;
945
946 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
947 return 0;
948
949 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
950 return 0;
951
952 if (!asn1_oid_decode(ctx, end, &trap->id, &trap->id_len))
953 return 0;
954
955 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
956 goto err_id_free;
957
958 if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_IPA) ||
959 (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_OTS)))
960 goto err_id_free;
961
962 if (!asn1_octets_decode(ctx, end, (unsigned char **)&trap->ip_address, &len))
963 goto err_id_free;
964
965 /* IPv4 only */
966 if (len != 4)
967 goto err_addr_free;
968
969 mangle_address(ctx->begin, ctx->pointer - 4, map, check);
970
971 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
972 goto err_addr_free;
973
974 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
975 goto err_addr_free;
976
977 if (!asn1_uint_decode(ctx, end, &trap->general))
978 goto err_addr_free;
979
980 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
981 goto err_addr_free;
982
983 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
984 goto err_addr_free;
985
986 if (!asn1_uint_decode(ctx, end, &trap->specific))
987 goto err_addr_free;
988
989 if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
990 goto err_addr_free;
991
992 if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_TIT) ||
993 (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_INT)))
994 goto err_addr_free;
995
996 if (!asn1_ulong_decode(ctx, end, &trap->time))
997 goto err_addr_free;
998
999 return 1;
1000
1001 err_id_free:
1002 kfree(trap->id);
1003
1004 err_addr_free:
1005 kfree((unsigned long *)trap->ip_address);
1006
1007 return 0;
1008 }
1009
1010 /*****************************************************************************
1011 *
1012 * Misc. routines
1013 *
1014 *****************************************************************************/
1015
1016 static void hex_dump(unsigned char *buf, size_t len)
1017 {
1018 size_t i;
1019
1020 for (i = 0; i < len; i++) {
1021 if (i && !(i % 16))
1022 printk("\n");
1023 printk("%02x ", *(buf + i));
1024 }
1025 printk("\n");
1026 }
1027
1028 /*
1029 * Parse and mangle SNMP message according to mapping.
1030 * (And this is the fucking 'basic' method).
1031 */
1032 static int snmp_parse_mangle(unsigned char *msg,
1033 u_int16_t len,
1034 const struct oct1_map *map,
1035 u_int16_t *check)
1036 {
1037 unsigned char *eoc, *end;
1038 unsigned int cls, con, tag, vers, pdutype;
1039 struct asn1_ctx ctx;
1040 struct asn1_octstr comm;
1041 struct snmp_object **obj;
1042
1043 if (debug > 1)
1044 hex_dump(msg, len);
1045
1046 asn1_open(&ctx, msg, len);
1047
1048 /*
1049 * Start of SNMP message.
1050 */
1051 if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
1052 return 0;
1053 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
1054 return 0;
1055
1056 /*
1057 * Version 1 or 2 handled.
1058 */
1059 if (!asn1_header_decode(&ctx, &end, &cls, &con, &tag))
1060 return 0;
1061 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
1062 return 0;
1063 if (!asn1_uint_decode (&ctx, end, &vers))
1064 return 0;
1065 if (debug > 1)
1066 printk(KERN_DEBUG "bsalg: snmp version: %u\n", vers + 1);
1067 if (vers > 1)
1068 return 1;
1069
1070 /*
1071 * Community.
1072 */
1073 if (!asn1_header_decode (&ctx, &end, &cls, &con, &tag))
1074 return 0;
1075 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OTS)
1076 return 0;
1077 if (!asn1_octets_decode(&ctx, end, &comm.data, &comm.len))
1078 return 0;
1079 if (debug > 1) {
1080 unsigned int i;
1081
1082 printk(KERN_DEBUG "bsalg: community: ");
1083 for (i = 0; i < comm.len; i++)
1084 printk("%c", comm.data[i]);
1085 printk("\n");
1086 }
1087 kfree(comm.data);
1088
1089 /*
1090 * PDU type
1091 */
1092 if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &pdutype))
1093 return 0;
1094 if (cls != ASN1_CTX || con != ASN1_CON)
1095 return 0;
1096 if (debug > 1) {
1097 unsigned char *pdus[] = {
1098 [SNMP_PDU_GET] = "get",
1099 [SNMP_PDU_NEXT] = "get-next",
1100 [SNMP_PDU_RESPONSE] = "response",
1101 [SNMP_PDU_SET] = "set",
1102 [SNMP_PDU_TRAP1] = "trapv1",
1103 [SNMP_PDU_BULK] = "bulk",
1104 [SNMP_PDU_INFORM] = "inform",
1105 [SNMP_PDU_TRAP2] = "trapv2"
1106 };
1107
1108 if (pdutype > SNMP_PDU_TRAP2)
1109 printk(KERN_DEBUG "bsalg: bad pdu type %u\n", pdutype);
1110 else
1111 printk(KERN_DEBUG "bsalg: pdu: %s\n", pdus[pdutype]);
1112 }
1113 if (pdutype != SNMP_PDU_RESPONSE &&
1114 pdutype != SNMP_PDU_TRAP1 && pdutype != SNMP_PDU_TRAP2)
1115 return 1;
1116
1117 /*
1118 * Request header or v1 trap
1119 */
1120 if (pdutype == SNMP_PDU_TRAP1) {
1121 struct snmp_v1_trap trap;
1122 unsigned char ret = snmp_trap_decode(&ctx, &trap, map, check);
1123
1124 /* Discard trap allocations regardless */
1125 kfree(trap.id);
1126 kfree((unsigned long *)trap.ip_address);
1127
1128 if (!ret)
1129 return ret;
1130
1131 } else {
1132 struct snmp_request req;
1133
1134 if (!snmp_request_decode(&ctx, &req))
1135 return 0;
1136
1137 if (debug > 1)
1138 printk(KERN_DEBUG "bsalg: request: id=0x%lx error_status=%u "
1139 "error_index=%u\n", req.id, req.error_status,
1140 req.error_index);
1141 }
1142
1143 /*
1144 * Loop through objects, look for IP addresses to mangle.
1145 */
1146 if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
1147 return 0;
1148
1149 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
1150 return 0;
1151
1152 obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
1153 if (obj == NULL) {
1154 if (net_ratelimit())
1155 printk(KERN_WARNING "OOM in bsalg(%d)\n", __LINE__);
1156 return 0;
1157 }
1158
1159 while (!asn1_eoc_decode(&ctx, eoc)) {
1160 unsigned int i;
1161
1162 if (!snmp_object_decode(&ctx, obj)) {
1163 if (*obj) {
1164 if ((*obj)->id)
1165 kfree((*obj)->id);
1166 kfree(*obj);
1167 }
1168 kfree(obj);
1169 return 0;
1170 }
1171
1172 if (debug > 1) {
1173 printk(KERN_DEBUG "bsalg: object: ");
1174 for (i = 0; i < (*obj)->id_len; i++) {
1175 if (i > 0)
1176 printk(".");
1177 printk("%lu", (*obj)->id[i]);
1178 }
1179 printk(": type=%u\n", (*obj)->type);
1180
1181 }
1182
1183 if ((*obj)->type == SNMP_IPADDR)
1184 mangle_address(ctx.begin, ctx.pointer - 4 , map, check);
1185
1186 kfree((*obj)->id);
1187 kfree(*obj);
1188 }
1189 kfree(obj);
1190
1191 if (!asn1_eoc_decode(&ctx, eoc))
1192 return 0;
1193
1194 return 1;
1195 }
1196
1197 /*****************************************************************************
1198 *
1199 * NAT routines.
1200 *
1201 *****************************************************************************/
1202
1203 /*
1204 * SNMP translation routine.
1205 */
1206 static int snmp_translate(struct ip_conntrack *ct,
1207 enum ip_conntrack_info ctinfo,
1208 struct sk_buff **pskb)
1209 {
1210 struct iphdr *iph = (*pskb)->nh.iph;
1211 struct udphdr *udph = (struct udphdr *)((u_int32_t *)iph + iph->ihl);
1212 u_int16_t udplen = ntohs(udph->len);
1213 u_int16_t paylen = udplen - sizeof(struct udphdr);
1214 int dir = CTINFO2DIR(ctinfo);
1215 struct oct1_map map;
1216
1217 /*
1218 * Determine mappping for application layer addresses based
1219 * on NAT manipulations for the packet.
1220 */
1221 if (dir == IP_CT_DIR_ORIGINAL) {
1222 /* SNAT traps */
1223 map.from = NOCT1(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip);
1224 map.to = NOCT1(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip);
1225 } else {
1226 /* DNAT replies */
1227 map.from = NOCT1(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
1228 map.to = NOCT1(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip);
1229 }
1230
1231 if (map.from == map.to)
1232 return NF_ACCEPT;
1233
1234 if (!snmp_parse_mangle((unsigned char *)udph + sizeof(struct udphdr),
1235 paylen, &map, &udph->check)) {
1236 if (net_ratelimit())
1237 printk(KERN_WARNING "bsalg: parser failed\n");
1238 return NF_DROP;
1239 }
1240 return NF_ACCEPT;
1241 }
1242
1243 /* We don't actually set up expectations, just adjust internal IP
1244 * addresses if this is being NATted */
1245 static int help(struct sk_buff **pskb,
1246 struct ip_conntrack *ct,
1247 enum ip_conntrack_info ctinfo)
1248 {
1249 int dir = CTINFO2DIR(ctinfo);
1250 unsigned int ret;
1251 struct iphdr *iph = (*pskb)->nh.iph;
1252 struct udphdr *udph = (struct udphdr *)((u_int32_t *)iph + iph->ihl);
1253
1254 /* SNMP replies and originating SNMP traps get mangled */
1255 if (udph->source == ntohs(SNMP_PORT) && dir != IP_CT_DIR_REPLY)
1256 return NF_ACCEPT;
1257 if (udph->dest == ntohs(SNMP_TRAP_PORT) && dir != IP_CT_DIR_ORIGINAL)
1258 return NF_ACCEPT;
1259
1260 /* No NAT? */
1261 if (!(ct->status & IPS_NAT_MASK))
1262 return NF_ACCEPT;
1263
1264 /*
1265 * Make sure the packet length is ok. So far, we were only guaranteed
1266 * to have a valid length IP header plus 8 bytes, which means we have
1267 * enough room for a UDP header. Just verify the UDP length field so we
1268 * can mess around with the payload.
1269 */
1270 if (ntohs(udph->len) != (*pskb)->len - (iph->ihl << 2)) {
1271 if (net_ratelimit())
1272 printk(KERN_WARNING "SNMP: dropping malformed packet "
1273 "src=%u.%u.%u.%u dst=%u.%u.%u.%u\n",
1274 NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
1275 return NF_DROP;
1276 }
1277
1278 if (!skb_ip_make_writable(pskb, (*pskb)->len))
1279 return NF_DROP;
1280
1281 spin_lock_bh(&snmp_lock);
1282 ret = snmp_translate(ct, ctinfo, pskb);
1283 spin_unlock_bh(&snmp_lock);
1284 return ret;
1285 }
1286
1287 static struct ip_conntrack_helper snmp_helper = {
1288 .max_expected = 0,
1289 .timeout = 180,
1290 .me = THIS_MODULE,
1291 .help = help,
1292 .name = "snmp",
1293
1294 .tuple = { .src = { .u = { __constant_htons(SNMP_PORT) } },
1295 .dst = { .protonum = IPPROTO_UDP },
1296 },
1297 .mask = { .src = { .u = { 0xFFFF } },
1298 .dst = { .protonum = 0xFF },
1299 },
1300 };
1301
1302 static struct ip_conntrack_helper snmp_trap_helper = {
1303 .max_expected = 0,
1304 .timeout = 180,
1305 .me = THIS_MODULE,
1306 .help = help,
1307 .name = "snmp_trap",
1308
1309 .tuple = { .src = { .u = { __constant_htons(SNMP_TRAP_PORT) } },
1310 .dst = { .protonum = IPPROTO_UDP },
1311 },
1312 .mask = { .src = { .u = { 0xFFFF } },
1313 .dst = { .protonum = 0xFF },
1314 },
1315 };
1316
1317 /*****************************************************************************
1318 *
1319 * Module stuff.
1320 *
1321 *****************************************************************************/
1322
1323 static int __init init(void)
1324 {
1325 int ret = 0;
1326
1327 ret = ip_conntrack_helper_register(&snmp_helper);
1328 if (ret < 0)
1329 return ret;
1330 ret = ip_conntrack_helper_register(&snmp_trap_helper);
1331 if (ret < 0) {
1332 ip_conntrack_helper_unregister(&snmp_helper);
1333 return ret;
1334 }
1335 return ret;
1336 }
1337
1338 static void __exit fini(void)
1339 {
1340 ip_conntrack_helper_unregister(&snmp_helper);
1341 ip_conntrack_helper_unregister(&snmp_trap_helper);
1342 }
1343
1344 module_init(init);
1345 module_exit(fini);
1346
1347 module_param(debug, bool, 0600);
Linux 2.6 ibm-acpi/thinkpad-acpi driver git tree