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807467c2 PM |
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> | |
807467c2 PM |
41 | */ |
42 | #include <linux/module.h> | |
43 | #include <linux/moduleparam.h> | |
44 | #include <linux/types.h> | |
45 | #include <linux/kernel.h> | |
5a0e3ad6 | 46 | #include <linux/slab.h> |
807467c2 PM |
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> | |
6002f266 | 54 | #include <net/netfilter/nf_conntrack_expect.h> |
807467c2 PM |
55 | #include <net/netfilter/nf_conntrack_helper.h> |
56 | #include <net/netfilter/nf_nat_helper.h> | |
93557f53 | 57 | #include <linux/netfilter/nf_conntrack_snmp.h> |
807467c2 PM |
58 | |
59 | MODULE_LICENSE("GPL"); | |
60 | MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); | |
61 | MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway"); | |
62 | MODULE_ALIAS("ip_nat_snmp_basic"); | |
63 | ||
64 | #define SNMP_PORT 161 | |
65 | #define SNMP_TRAP_PORT 162 | |
e79ec50b | 66 | #define NOCT1(n) (*(u8 *)(n)) |
807467c2 PM |
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, | |
e905a9ed YH |
152 | unsigned char *buf, |
153 | unsigned int len) | |
807467c2 PM |
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, | |
e905a9ed YH |
188 | unsigned int *cls, |
189 | unsigned int *con, | |
190 | unsigned int *tag) | |
807467c2 PM |
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, | |
e905a9ed YH |
209 | unsigned int *def, |
210 | unsigned int *len) | |
807467c2 PM |
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 { | |
72b72949 | 225 | cnt = ch & 0x7F; |
807467c2 PM |
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 | } | |
ddb2c435 CW |
237 | |
238 | /* don't trust len bigger than ctx buffer */ | |
239 | if (*len > ctx->end - ctx->pointer) | |
240 | return 0; | |
241 | ||
807467c2 PM |
242 | return 1; |
243 | } | |
244 | ||
245 | static unsigned char asn1_header_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
246 | unsigned char **eoc, |
247 | unsigned int *cls, | |
248 | unsigned int *con, | |
249 | unsigned int *tag) | |
807467c2 PM |
250 | { |
251 | unsigned int def, len; | |
252 | ||
253 | if (!asn1_id_decode(ctx, cls, con, tag)) | |
254 | return 0; | |
255 | ||
256 | def = len = 0; | |
257 | if (!asn1_length_decode(ctx, &def, &len)) | |
258 | return 0; | |
259 | ||
ddb2c435 CW |
260 | /* primitive shall be definite, indefinite shall be constructed */ |
261 | if (*con == ASN1_PRI && !def) | |
262 | return 0; | |
263 | ||
807467c2 PM |
264 | if (def) |
265 | *eoc = ctx->pointer + len; | |
266 | else | |
267 | *eoc = NULL; | |
268 | return 1; | |
269 | } | |
270 | ||
271 | static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc) | |
272 | { | |
273 | unsigned char ch; | |
274 | ||
06aa1072 | 275 | if (eoc == NULL) { |
807467c2 PM |
276 | if (!asn1_octet_decode(ctx, &ch)) |
277 | return 0; | |
278 | ||
279 | if (ch != 0x00) { | |
280 | ctx->error = ASN1_ERR_DEC_EOC_MISMATCH; | |
281 | return 0; | |
282 | } | |
283 | ||
284 | if (!asn1_octet_decode(ctx, &ch)) | |
285 | return 0; | |
286 | ||
287 | if (ch != 0x00) { | |
288 | ctx->error = ASN1_ERR_DEC_EOC_MISMATCH; | |
289 | return 0; | |
290 | } | |
291 | return 1; | |
292 | } else { | |
293 | if (ctx->pointer != eoc) { | |
294 | ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH; | |
295 | return 0; | |
296 | } | |
297 | return 1; | |
298 | } | |
299 | } | |
300 | ||
301 | static unsigned char asn1_null_decode(struct asn1_ctx *ctx, unsigned char *eoc) | |
302 | { | |
303 | ctx->pointer = eoc; | |
304 | return 1; | |
305 | } | |
306 | ||
307 | static unsigned char asn1_long_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
308 | unsigned char *eoc, |
309 | long *integer) | |
807467c2 PM |
310 | { |
311 | unsigned char ch; | |
312 | unsigned int len; | |
313 | ||
314 | if (!asn1_octet_decode(ctx, &ch)) | |
315 | return 0; | |
316 | ||
317 | *integer = (signed char) ch; | |
318 | len = 1; | |
319 | ||
320 | while (ctx->pointer < eoc) { | |
321 | if (++len > sizeof (long)) { | |
322 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
323 | return 0; | |
324 | } | |
325 | ||
326 | if (!asn1_octet_decode(ctx, &ch)) | |
327 | return 0; | |
328 | ||
329 | *integer <<= 8; | |
330 | *integer |= ch; | |
331 | } | |
332 | return 1; | |
333 | } | |
334 | ||
335 | static unsigned char asn1_uint_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
336 | unsigned char *eoc, |
337 | unsigned int *integer) | |
807467c2 PM |
338 | { |
339 | unsigned char ch; | |
340 | unsigned int len; | |
341 | ||
342 | if (!asn1_octet_decode(ctx, &ch)) | |
343 | return 0; | |
344 | ||
345 | *integer = ch; | |
346 | if (ch == 0) len = 0; | |
347 | else len = 1; | |
348 | ||
349 | while (ctx->pointer < eoc) { | |
350 | if (++len > sizeof (unsigned int)) { | |
351 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
352 | return 0; | |
353 | } | |
354 | ||
355 | if (!asn1_octet_decode(ctx, &ch)) | |
356 | return 0; | |
357 | ||
358 | *integer <<= 8; | |
359 | *integer |= ch; | |
360 | } | |
361 | return 1; | |
362 | } | |
363 | ||
364 | static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
365 | unsigned char *eoc, |
366 | unsigned long *integer) | |
807467c2 PM |
367 | { |
368 | unsigned char ch; | |
369 | unsigned int len; | |
370 | ||
371 | if (!asn1_octet_decode(ctx, &ch)) | |
372 | return 0; | |
373 | ||
374 | *integer = ch; | |
375 | if (ch == 0) len = 0; | |
376 | else len = 1; | |
377 | ||
378 | while (ctx->pointer < eoc) { | |
379 | if (++len > sizeof (unsigned long)) { | |
380 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
381 | return 0; | |
382 | } | |
383 | ||
384 | if (!asn1_octet_decode(ctx, &ch)) | |
385 | return 0; | |
386 | ||
387 | *integer <<= 8; | |
388 | *integer |= ch; | |
389 | } | |
390 | return 1; | |
391 | } | |
392 | ||
393 | static unsigned char asn1_octets_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
394 | unsigned char *eoc, |
395 | unsigned char **octets, | |
396 | unsigned int *len) | |
807467c2 PM |
397 | { |
398 | unsigned char *ptr; | |
399 | ||
400 | *len = 0; | |
401 | ||
402 | *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC); | |
0a9ee813 | 403 | if (*octets == NULL) |
807467c2 | 404 | return 0; |
807467c2 PM |
405 | |
406 | ptr = *octets; | |
407 | while (ctx->pointer < eoc) { | |
408 | if (!asn1_octet_decode(ctx, (unsigned char *)ptr++)) { | |
409 | kfree(*octets); | |
410 | *octets = NULL; | |
411 | return 0; | |
412 | } | |
413 | (*len)++; | |
414 | } | |
415 | return 1; | |
416 | } | |
417 | ||
418 | static unsigned char asn1_subid_decode(struct asn1_ctx *ctx, | |
e905a9ed | 419 | unsigned long *subid) |
807467c2 PM |
420 | { |
421 | unsigned char ch; | |
422 | ||
423 | *subid = 0; | |
424 | ||
425 | do { | |
426 | if (!asn1_octet_decode(ctx, &ch)) | |
427 | return 0; | |
428 | ||
429 | *subid <<= 7; | |
430 | *subid |= ch & 0x7F; | |
431 | } while ((ch & 0x80) == 0x80); | |
432 | return 1; | |
433 | } | |
434 | ||
435 | static unsigned char asn1_oid_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
436 | unsigned char *eoc, |
437 | unsigned long **oid, | |
438 | unsigned int *len) | |
807467c2 PM |
439 | { |
440 | unsigned long subid; | |
807467c2 | 441 | unsigned long *optr; |
252815b0 | 442 | size_t size; |
807467c2 PM |
443 | |
444 | size = eoc - ctx->pointer + 1; | |
ddb2c435 CW |
445 | |
446 | /* first subid actually encodes first two subids */ | |
447 | if (size < 2 || size > ULONG_MAX/sizeof(unsigned long)) | |
448 | return 0; | |
449 | ||
807467c2 | 450 | *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC); |
0a9ee813 | 451 | if (*oid == NULL) |
807467c2 | 452 | return 0; |
807467c2 PM |
453 | |
454 | optr = *oid; | |
455 | ||
456 | if (!asn1_subid_decode(ctx, &subid)) { | |
457 | kfree(*oid); | |
458 | *oid = NULL; | |
459 | return 0; | |
460 | } | |
461 | ||
462 | if (subid < 40) { | |
463 | optr [0] = 0; | |
464 | optr [1] = subid; | |
465 | } else if (subid < 80) { | |
466 | optr [0] = 1; | |
467 | optr [1] = subid - 40; | |
468 | } else { | |
469 | optr [0] = 2; | |
470 | optr [1] = subid - 80; | |
471 | } | |
472 | ||
473 | *len = 2; | |
474 | optr += 2; | |
475 | ||
476 | while (ctx->pointer < eoc) { | |
477 | if (++(*len) > size) { | |
478 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
479 | kfree(*oid); | |
480 | *oid = NULL; | |
481 | return 0; | |
482 | } | |
483 | ||
484 | if (!asn1_subid_decode(ctx, optr++)) { | |
485 | kfree(*oid); | |
486 | *oid = NULL; | |
487 | return 0; | |
488 | } | |
489 | } | |
490 | return 1; | |
491 | } | |
492 | ||
493 | /***************************************************************************** | |
494 | * | |
495 | * SNMP decoding routines (gxsnmp author Dirk Wisse) | |
496 | * | |
497 | *****************************************************************************/ | |
498 | ||
499 | /* SNMP Versions */ | |
500 | #define SNMP_V1 0 | |
501 | #define SNMP_V2C 1 | |
502 | #define SNMP_V2 2 | |
503 | #define SNMP_V3 3 | |
504 | ||
505 | /* Default Sizes */ | |
506 | #define SNMP_SIZE_COMM 256 | |
507 | #define SNMP_SIZE_OBJECTID 128 | |
508 | #define SNMP_SIZE_BUFCHR 256 | |
509 | #define SNMP_SIZE_BUFINT 128 | |
510 | #define SNMP_SIZE_SMALLOBJECTID 16 | |
511 | ||
512 | /* Requests */ | |
513 | #define SNMP_PDU_GET 0 | |
514 | #define SNMP_PDU_NEXT 1 | |
515 | #define SNMP_PDU_RESPONSE 2 | |
516 | #define SNMP_PDU_SET 3 | |
517 | #define SNMP_PDU_TRAP1 4 | |
518 | #define SNMP_PDU_BULK 5 | |
519 | #define SNMP_PDU_INFORM 6 | |
520 | #define SNMP_PDU_TRAP2 7 | |
521 | ||
522 | /* Errors */ | |
523 | #define SNMP_NOERROR 0 | |
524 | #define SNMP_TOOBIG 1 | |
525 | #define SNMP_NOSUCHNAME 2 | |
526 | #define SNMP_BADVALUE 3 | |
527 | #define SNMP_READONLY 4 | |
528 | #define SNMP_GENERROR 5 | |
529 | #define SNMP_NOACCESS 6 | |
530 | #define SNMP_WRONGTYPE 7 | |
531 | #define SNMP_WRONGLENGTH 8 | |
532 | #define SNMP_WRONGENCODING 9 | |
533 | #define SNMP_WRONGVALUE 10 | |
534 | #define SNMP_NOCREATION 11 | |
535 | #define SNMP_INCONSISTENTVALUE 12 | |
536 | #define SNMP_RESOURCEUNAVAILABLE 13 | |
537 | #define SNMP_COMMITFAILED 14 | |
538 | #define SNMP_UNDOFAILED 15 | |
539 | #define SNMP_AUTHORIZATIONERROR 16 | |
540 | #define SNMP_NOTWRITABLE 17 | |
541 | #define SNMP_INCONSISTENTNAME 18 | |
542 | ||
543 | /* General SNMP V1 Traps */ | |
544 | #define SNMP_TRAP_COLDSTART 0 | |
545 | #define SNMP_TRAP_WARMSTART 1 | |
546 | #define SNMP_TRAP_LINKDOWN 2 | |
547 | #define SNMP_TRAP_LINKUP 3 | |
548 | #define SNMP_TRAP_AUTFAILURE 4 | |
549 | #define SNMP_TRAP_EQPNEIGHBORLOSS 5 | |
550 | #define SNMP_TRAP_ENTSPECIFIC 6 | |
551 | ||
552 | /* SNMPv1 Types */ | |
553 | #define SNMP_NULL 0 | |
554 | #define SNMP_INTEGER 1 /* l */ | |
555 | #define SNMP_OCTETSTR 2 /* c */ | |
556 | #define SNMP_DISPLAYSTR 2 /* c */ | |
557 | #define SNMP_OBJECTID 3 /* ul */ | |
558 | #define SNMP_IPADDR 4 /* uc */ | |
559 | #define SNMP_COUNTER 5 /* ul */ | |
560 | #define SNMP_GAUGE 6 /* ul */ | |
561 | #define SNMP_TIMETICKS 7 /* ul */ | |
562 | #define SNMP_OPAQUE 8 /* c */ | |
563 | ||
564 | /* Additional SNMPv2 Types */ | |
565 | #define SNMP_UINTEGER 5 /* ul */ | |
566 | #define SNMP_BITSTR 9 /* uc */ | |
567 | #define SNMP_NSAP 10 /* uc */ | |
568 | #define SNMP_COUNTER64 11 /* ul */ | |
569 | #define SNMP_NOSUCHOBJECT 12 | |
570 | #define SNMP_NOSUCHINSTANCE 13 | |
571 | #define SNMP_ENDOFMIBVIEW 14 | |
572 | ||
573 | union snmp_syntax | |
574 | { | |
575 | unsigned char uc[0]; /* 8 bit unsigned */ | |
576 | char c[0]; /* 8 bit signed */ | |
577 | unsigned long ul[0]; /* 32 bit unsigned */ | |
578 | long l[0]; /* 32 bit signed */ | |
579 | }; | |
580 | ||
581 | struct snmp_object | |
582 | { | |
583 | unsigned long *id; | |
584 | unsigned int id_len; | |
585 | unsigned short type; | |
586 | unsigned int syntax_len; | |
587 | union snmp_syntax syntax; | |
588 | }; | |
589 | ||
590 | struct snmp_request | |
591 | { | |
592 | unsigned long id; | |
593 | unsigned int error_status; | |
594 | unsigned int error_index; | |
595 | }; | |
596 | ||
597 | struct snmp_v1_trap | |
598 | { | |
599 | unsigned long *id; | |
600 | unsigned int id_len; | |
601 | unsigned long ip_address; /* pointer */ | |
602 | unsigned int general; | |
603 | unsigned int specific; | |
604 | unsigned long time; | |
605 | }; | |
606 | ||
607 | /* SNMP types */ | |
608 | #define SNMP_IPA 0 | |
609 | #define SNMP_CNT 1 | |
610 | #define SNMP_GGE 2 | |
611 | #define SNMP_TIT 3 | |
612 | #define SNMP_OPQ 4 | |
613 | #define SNMP_C64 6 | |
614 | ||
615 | /* SNMP errors */ | |
616 | #define SERR_NSO 0 | |
617 | #define SERR_NSI 1 | |
618 | #define SERR_EOM 2 | |
619 | ||
620 | static inline void mangle_address(unsigned char *begin, | |
e905a9ed YH |
621 | unsigned char *addr, |
622 | const struct oct1_map *map, | |
623 | __sum16 *check); | |
807467c2 PM |
624 | struct snmp_cnv |
625 | { | |
626 | unsigned int class; | |
627 | unsigned int tag; | |
628 | int syntax; | |
629 | }; | |
630 | ||
72b72949 | 631 | static const struct snmp_cnv snmp_conv[] = { |
807467c2 PM |
632 | {ASN1_UNI, ASN1_NUL, SNMP_NULL}, |
633 | {ASN1_UNI, ASN1_INT, SNMP_INTEGER}, | |
634 | {ASN1_UNI, ASN1_OTS, SNMP_OCTETSTR}, | |
635 | {ASN1_UNI, ASN1_OTS, SNMP_DISPLAYSTR}, | |
636 | {ASN1_UNI, ASN1_OJI, SNMP_OBJECTID}, | |
637 | {ASN1_APL, SNMP_IPA, SNMP_IPADDR}, | |
638 | {ASN1_APL, SNMP_CNT, SNMP_COUNTER}, /* Counter32 */ | |
639 | {ASN1_APL, SNMP_GGE, SNMP_GAUGE}, /* Gauge32 == Unsigned32 */ | |
640 | {ASN1_APL, SNMP_TIT, SNMP_TIMETICKS}, | |
641 | {ASN1_APL, SNMP_OPQ, SNMP_OPAQUE}, | |
642 | ||
643 | /* SNMPv2 data types and errors */ | |
644 | {ASN1_UNI, ASN1_BTS, SNMP_BITSTR}, | |
645 | {ASN1_APL, SNMP_C64, SNMP_COUNTER64}, | |
646 | {ASN1_CTX, SERR_NSO, SNMP_NOSUCHOBJECT}, | |
647 | {ASN1_CTX, SERR_NSI, SNMP_NOSUCHINSTANCE}, | |
648 | {ASN1_CTX, SERR_EOM, SNMP_ENDOFMIBVIEW}, | |
649 | {0, 0, -1} | |
650 | }; | |
651 | ||
652 | static unsigned char snmp_tag_cls2syntax(unsigned int tag, | |
e905a9ed YH |
653 | unsigned int cls, |
654 | unsigned short *syntax) | |
807467c2 | 655 | { |
72b72949 | 656 | const struct snmp_cnv *cnv; |
807467c2 PM |
657 | |
658 | cnv = snmp_conv; | |
659 | ||
660 | while (cnv->syntax != -1) { | |
661 | if (cnv->tag == tag && cnv->class == cls) { | |
662 | *syntax = cnv->syntax; | |
663 | return 1; | |
664 | } | |
665 | cnv++; | |
666 | } | |
667 | return 0; | |
668 | } | |
669 | ||
670 | static unsigned char snmp_object_decode(struct asn1_ctx *ctx, | |
e905a9ed | 671 | struct snmp_object **obj) |
807467c2 PM |
672 | { |
673 | unsigned int cls, con, tag, len, idlen; | |
674 | unsigned short type; | |
675 | unsigned char *eoc, *end, *p; | |
676 | unsigned long *lp, *id; | |
677 | unsigned long ul; | |
678 | long l; | |
679 | ||
680 | *obj = NULL; | |
681 | id = NULL; | |
682 | ||
683 | if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag)) | |
684 | return 0; | |
685 | ||
686 | if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) | |
687 | return 0; | |
688 | ||
689 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
690 | return 0; | |
691 | ||
692 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI) | |
693 | return 0; | |
694 | ||
695 | if (!asn1_oid_decode(ctx, end, &id, &idlen)) | |
696 | return 0; | |
697 | ||
698 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) { | |
699 | kfree(id); | |
700 | return 0; | |
701 | } | |
702 | ||
703 | if (con != ASN1_PRI) { | |
704 | kfree(id); | |
705 | return 0; | |
706 | } | |
707 | ||
708 | type = 0; | |
709 | if (!snmp_tag_cls2syntax(tag, cls, &type)) { | |
710 | kfree(id); | |
711 | return 0; | |
712 | } | |
713 | ||
714 | l = 0; | |
715 | switch (type) { | |
181b1e9c JP |
716 | case SNMP_INTEGER: |
717 | len = sizeof(long); | |
718 | if (!asn1_long_decode(ctx, end, &l)) { | |
719 | kfree(id); | |
720 | return 0; | |
721 | } | |
722 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
723 | if (*obj == NULL) { | |
724 | kfree(id); | |
181b1e9c JP |
725 | return 0; |
726 | } | |
727 | (*obj)->syntax.l[0] = l; | |
728 | break; | |
729 | case SNMP_OCTETSTR: | |
730 | case SNMP_OPAQUE: | |
731 | if (!asn1_octets_decode(ctx, end, &p, &len)) { | |
732 | kfree(id); | |
733 | return 0; | |
734 | } | |
735 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
736 | if (*obj == NULL) { | |
807467c2 | 737 | kfree(p); |
181b1e9c | 738 | kfree(id); |
181b1e9c JP |
739 | return 0; |
740 | } | |
741 | memcpy((*obj)->syntax.c, p, len); | |
742 | kfree(p); | |
743 | break; | |
744 | case SNMP_NULL: | |
745 | case SNMP_NOSUCHOBJECT: | |
746 | case SNMP_NOSUCHINSTANCE: | |
747 | case SNMP_ENDOFMIBVIEW: | |
748 | len = 0; | |
749 | *obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC); | |
750 | if (*obj == NULL) { | |
751 | kfree(id); | |
181b1e9c JP |
752 | return 0; |
753 | } | |
754 | if (!asn1_null_decode(ctx, end)) { | |
755 | kfree(id); | |
756 | kfree(*obj); | |
757 | *obj = NULL; | |
758 | return 0; | |
759 | } | |
760 | break; | |
761 | case SNMP_OBJECTID: | |
762 | if (!asn1_oid_decode(ctx, end, (unsigned long **)&lp, &len)) { | |
763 | kfree(id); | |
764 | return 0; | |
765 | } | |
766 | len *= sizeof(unsigned long); | |
767 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
768 | if (*obj == NULL) { | |
807467c2 | 769 | kfree(lp); |
181b1e9c | 770 | kfree(id); |
181b1e9c JP |
771 | return 0; |
772 | } | |
773 | memcpy((*obj)->syntax.ul, lp, len); | |
774 | kfree(lp); | |
775 | break; | |
776 | case SNMP_IPADDR: | |
777 | if (!asn1_octets_decode(ctx, end, &p, &len)) { | |
778 | kfree(id); | |
779 | return 0; | |
780 | } | |
781 | if (len != 4) { | |
807467c2 | 782 | kfree(p); |
807467c2 PM |
783 | kfree(id); |
784 | return 0; | |
181b1e9c JP |
785 | } |
786 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
787 | if (*obj == NULL) { | |
788 | kfree(p); | |
789 | kfree(id); | |
181b1e9c JP |
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); | |
181b1e9c JP |
806 | return 0; |
807 | } | |
808 | (*obj)->syntax.ul[0] = ul; | |
809 | break; | |
810 | default: | |
811 | kfree(id); | |
812 | return 0; | |
807467c2 PM |
813 | } |
814 | ||
815 | (*obj)->syntax_len = len; | |
816 | (*obj)->type = type; | |
817 | (*obj)->id = id; | |
818 | (*obj)->id_len = idlen; | |
819 | ||
820 | if (!asn1_eoc_decode(ctx, eoc)) { | |
821 | kfree(id); | |
822 | kfree(*obj); | |
823 | *obj = NULL; | |
824 | return 0; | |
825 | } | |
826 | return 1; | |
827 | } | |
828 | ||
829 | static unsigned char snmp_request_decode(struct asn1_ctx *ctx, | |
e905a9ed | 830 | struct snmp_request *request) |
807467c2 PM |
831 | { |
832 | unsigned int cls, con, tag; | |
833 | unsigned char *end; | |
834 | ||
835 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
836 | return 0; | |
837 | ||
838 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
839 | return 0; | |
840 | ||
841 | if (!asn1_ulong_decode(ctx, end, &request->id)) | |
842 | return 0; | |
843 | ||
844 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
845 | return 0; | |
846 | ||
847 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
848 | return 0; | |
849 | ||
850 | if (!asn1_uint_decode(ctx, end, &request->error_status)) | |
851 | return 0; | |
852 | ||
853 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
854 | return 0; | |
855 | ||
856 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
857 | return 0; | |
858 | ||
859 | if (!asn1_uint_decode(ctx, end, &request->error_index)) | |
860 | return 0; | |
861 | ||
862 | return 1; | |
863 | } | |
864 | ||
865 | /* | |
866 | * Fast checksum update for possibly oddly-aligned UDP byte, from the | |
867 | * code example in the draft. | |
868 | */ | |
869 | static void fast_csum(__sum16 *csum, | |
e905a9ed YH |
870 | const unsigned char *optr, |
871 | const unsigned char *nptr, | |
872 | int offset) | |
807467c2 PM |
873 | { |
874 | unsigned char s[4]; | |
875 | ||
876 | if (offset & 1) { | |
d6120b8a | 877 | s[0] = ~0; |
807467c2 | 878 | s[1] = ~*optr; |
d6120b8a | 879 | s[2] = 0; |
807467c2 PM |
880 | s[3] = *nptr; |
881 | } else { | |
807467c2 | 882 | s[0] = ~*optr; |
d6120b8a | 883 | s[1] = ~0; |
807467c2 | 884 | s[2] = *nptr; |
d6120b8a | 885 | s[3] = 0; |
807467c2 PM |
886 | } |
887 | ||
888 | *csum = csum_fold(csum_partial(s, 4, ~csum_unfold(*csum))); | |
889 | } | |
890 | ||
891 | /* | |
892 | * Mangle IP address. | |
893 | * - begin points to the start of the snmp messgae | |
894 | * - addr points to the start of the address | |
895 | */ | |
896 | static inline void mangle_address(unsigned char *begin, | |
e905a9ed YH |
897 | unsigned char *addr, |
898 | const struct oct1_map *map, | |
899 | __sum16 *check) | |
807467c2 PM |
900 | { |
901 | if (map->from == NOCT1(addr)) { | |
902 | u_int32_t old; | |
903 | ||
904 | if (debug) | |
72b72949 | 905 | memcpy(&old, addr, sizeof(old)); |
807467c2 PM |
906 | |
907 | *addr = map->to; | |
908 | ||
909 | /* Update UDP checksum if being used */ | |
910 | if (*check) { | |
911 | fast_csum(check, | |
e905a9ed | 912 | &map->from, &map->to, addr - begin); |
807467c2 PM |
913 | |
914 | } | |
915 | ||
916 | if (debug) | |
cffee385 HH |
917 | printk(KERN_DEBUG "bsalg: mapped %pI4 to %pI4\n", |
918 | &old, addr); | |
807467c2 PM |
919 | } |
920 | } | |
921 | ||
922 | static unsigned char snmp_trap_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
923 | struct snmp_v1_trap *trap, |
924 | const struct oct1_map *map, | |
925 | __sum16 *check) | |
807467c2 PM |
926 | { |
927 | unsigned int cls, con, tag, len; | |
928 | unsigned char *end; | |
929 | ||
930 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
931 | return 0; | |
932 | ||
933 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI) | |
934 | return 0; | |
935 | ||
936 | if (!asn1_oid_decode(ctx, end, &trap->id, &trap->id_len)) | |
937 | return 0; | |
938 | ||
939 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
940 | goto err_id_free; | |
941 | ||
942 | if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_IPA) || | |
943 | (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_OTS))) | |
944 | goto err_id_free; | |
945 | ||
946 | if (!asn1_octets_decode(ctx, end, (unsigned char **)&trap->ip_address, &len)) | |
947 | goto err_id_free; | |
948 | ||
949 | /* IPv4 only */ | |
950 | if (len != 4) | |
951 | goto err_addr_free; | |
952 | ||
953 | mangle_address(ctx->begin, ctx->pointer - 4, map, check); | |
954 | ||
955 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
956 | goto err_addr_free; | |
957 | ||
958 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
959 | goto err_addr_free; | |
960 | ||
961 | if (!asn1_uint_decode(ctx, end, &trap->general)) | |
962 | goto err_addr_free; | |
963 | ||
964 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
965 | goto err_addr_free; | |
966 | ||
967 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
968 | goto err_addr_free; | |
969 | ||
970 | if (!asn1_uint_decode(ctx, end, &trap->specific)) | |
971 | goto err_addr_free; | |
972 | ||
973 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
974 | goto err_addr_free; | |
975 | ||
976 | if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_TIT) || | |
977 | (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_INT))) | |
978 | goto err_addr_free; | |
979 | ||
980 | if (!asn1_ulong_decode(ctx, end, &trap->time)) | |
981 | goto err_addr_free; | |
982 | ||
983 | return 1; | |
984 | ||
985 | err_addr_free: | |
986 | kfree((unsigned long *)trap->ip_address); | |
987 | ||
988 | err_id_free: | |
989 | kfree(trap->id); | |
990 | ||
991 | return 0; | |
992 | } | |
993 | ||
994 | /***************************************************************************** | |
995 | * | |
996 | * Misc. routines | |
997 | * | |
998 | *****************************************************************************/ | |
999 | ||
72b72949 | 1000 | static void hex_dump(const unsigned char *buf, size_t len) |
807467c2 PM |
1001 | { |
1002 | size_t i; | |
1003 | ||
1004 | for (i = 0; i < len; i++) { | |
1005 | if (i && !(i % 16)) | |
1006 | printk("\n"); | |
1007 | printk("%02x ", *(buf + i)); | |
1008 | } | |
1009 | printk("\n"); | |
1010 | } | |
1011 | ||
1012 | /* | |
1013 | * Parse and mangle SNMP message according to mapping. | |
1014 | * (And this is the fucking 'basic' method). | |
1015 | */ | |
1016 | static int snmp_parse_mangle(unsigned char *msg, | |
e905a9ed YH |
1017 | u_int16_t len, |
1018 | const struct oct1_map *map, | |
1019 | __sum16 *check) | |
807467c2 PM |
1020 | { |
1021 | unsigned char *eoc, *end; | |
1022 | unsigned int cls, con, tag, vers, pdutype; | |
1023 | struct asn1_ctx ctx; | |
1024 | struct asn1_octstr comm; | |
71c3ebfd | 1025 | struct snmp_object *obj; |
807467c2 PM |
1026 | |
1027 | if (debug > 1) | |
1028 | hex_dump(msg, len); | |
1029 | ||
1030 | asn1_open(&ctx, msg, len); | |
1031 | ||
1032 | /* | |
1033 | * Start of SNMP message. | |
1034 | */ | |
1035 | if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag)) | |
1036 | return 0; | |
1037 | if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) | |
1038 | return 0; | |
1039 | ||
1040 | /* | |
1041 | * Version 1 or 2 handled. | |
1042 | */ | |
1043 | if (!asn1_header_decode(&ctx, &end, &cls, &con, &tag)) | |
1044 | return 0; | |
1045 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
1046 | return 0; | |
1047 | if (!asn1_uint_decode (&ctx, end, &vers)) | |
1048 | return 0; | |
1049 | if (debug > 1) | |
1050 | printk(KERN_DEBUG "bsalg: snmp version: %u\n", vers + 1); | |
1051 | if (vers > 1) | |
1052 | return 1; | |
1053 | ||
1054 | /* | |
1055 | * Community. | |
1056 | */ | |
1057 | if (!asn1_header_decode (&ctx, &end, &cls, &con, &tag)) | |
1058 | return 0; | |
1059 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OTS) | |
1060 | return 0; | |
1061 | if (!asn1_octets_decode(&ctx, end, &comm.data, &comm.len)) | |
1062 | return 0; | |
1063 | if (debug > 1) { | |
1064 | unsigned int i; | |
1065 | ||
1066 | printk(KERN_DEBUG "bsalg: community: "); | |
1067 | for (i = 0; i < comm.len; i++) | |
1068 | printk("%c", comm.data[i]); | |
1069 | printk("\n"); | |
1070 | } | |
1071 | kfree(comm.data); | |
1072 | ||
1073 | /* | |
1074 | * PDU type | |
1075 | */ | |
1076 | if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &pdutype)) | |
1077 | return 0; | |
1078 | if (cls != ASN1_CTX || con != ASN1_CON) | |
1079 | return 0; | |
1080 | if (debug > 1) { | |
72b72949 | 1081 | static const unsigned char *const pdus[] = { |
807467c2 PM |
1082 | [SNMP_PDU_GET] = "get", |
1083 | [SNMP_PDU_NEXT] = "get-next", | |
1084 | [SNMP_PDU_RESPONSE] = "response", | |
1085 | [SNMP_PDU_SET] = "set", | |
1086 | [SNMP_PDU_TRAP1] = "trapv1", | |
1087 | [SNMP_PDU_BULK] = "bulk", | |
1088 | [SNMP_PDU_INFORM] = "inform", | |
1089 | [SNMP_PDU_TRAP2] = "trapv2" | |
1090 | }; | |
1091 | ||
1092 | if (pdutype > SNMP_PDU_TRAP2) | |
1093 | printk(KERN_DEBUG "bsalg: bad pdu type %u\n", pdutype); | |
1094 | else | |
1095 | printk(KERN_DEBUG "bsalg: pdu: %s\n", pdus[pdutype]); | |
1096 | } | |
1097 | if (pdutype != SNMP_PDU_RESPONSE && | |
1098 | pdutype != SNMP_PDU_TRAP1 && pdutype != SNMP_PDU_TRAP2) | |
1099 | return 1; | |
1100 | ||
1101 | /* | |
1102 | * Request header or v1 trap | |
1103 | */ | |
1104 | if (pdutype == SNMP_PDU_TRAP1) { | |
1105 | struct snmp_v1_trap trap; | |
1106 | unsigned char ret = snmp_trap_decode(&ctx, &trap, map, check); | |
1107 | ||
1108 | if (ret) { | |
1109 | kfree(trap.id); | |
1110 | kfree((unsigned long *)trap.ip_address); | |
1111 | } else | |
1112 | return ret; | |
1113 | ||
1114 | } else { | |
1115 | struct snmp_request req; | |
1116 | ||
1117 | if (!snmp_request_decode(&ctx, &req)) | |
1118 | return 0; | |
1119 | ||
1120 | if (debug > 1) | |
1121 | printk(KERN_DEBUG "bsalg: request: id=0x%lx error_status=%u " | |
1122 | "error_index=%u\n", req.id, req.error_status, | |
1123 | req.error_index); | |
1124 | } | |
1125 | ||
1126 | /* | |
1127 | * Loop through objects, look for IP addresses to mangle. | |
1128 | */ | |
1129 | if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag)) | |
1130 | return 0; | |
1131 | ||
1132 | if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) | |
1133 | return 0; | |
1134 | ||
807467c2 PM |
1135 | while (!asn1_eoc_decode(&ctx, eoc)) { |
1136 | unsigned int i; | |
1137 | ||
71c3ebfd JL |
1138 | if (!snmp_object_decode(&ctx, &obj)) { |
1139 | if (obj) { | |
1140 | kfree(obj->id); | |
1141 | kfree(obj); | |
807467c2 | 1142 | } |
807467c2 PM |
1143 | return 0; |
1144 | } | |
1145 | ||
1146 | if (debug > 1) { | |
1147 | printk(KERN_DEBUG "bsalg: object: "); | |
71c3ebfd | 1148 | for (i = 0; i < obj->id_len; i++) { |
807467c2 PM |
1149 | if (i > 0) |
1150 | printk("."); | |
71c3ebfd | 1151 | printk("%lu", obj->id[i]); |
807467c2 | 1152 | } |
71c3ebfd | 1153 | printk(": type=%u\n", obj->type); |
807467c2 PM |
1154 | |
1155 | } | |
1156 | ||
71c3ebfd | 1157 | if (obj->type == SNMP_IPADDR) |
807467c2 PM |
1158 | mangle_address(ctx.begin, ctx.pointer - 4 , map, check); |
1159 | ||
71c3ebfd JL |
1160 | kfree(obj->id); |
1161 | kfree(obj); | |
807467c2 | 1162 | } |
807467c2 PM |
1163 | |
1164 | if (!asn1_eoc_decode(&ctx, eoc)) | |
1165 | return 0; | |
1166 | ||
1167 | return 1; | |
1168 | } | |
1169 | ||
1170 | /***************************************************************************** | |
1171 | * | |
1172 | * NAT routines. | |
1173 | * | |
1174 | *****************************************************************************/ | |
1175 | ||
1176 | /* | |
1177 | * SNMP translation routine. | |
1178 | */ | |
1179 | static int snmp_translate(struct nf_conn *ct, | |
e905a9ed | 1180 | enum ip_conntrack_info ctinfo, |
3db05fea | 1181 | struct sk_buff *skb) |
807467c2 | 1182 | { |
3db05fea | 1183 | struct iphdr *iph = ip_hdr(skb); |
807467c2 PM |
1184 | struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl); |
1185 | u_int16_t udplen = ntohs(udph->len); | |
1186 | u_int16_t paylen = udplen - sizeof(struct udphdr); | |
1187 | int dir = CTINFO2DIR(ctinfo); | |
1188 | struct oct1_map map; | |
1189 | ||
1190 | /* | |
1191 | * Determine mappping for application layer addresses based | |
1192 | * on NAT manipulations for the packet. | |
1193 | */ | |
1194 | if (dir == IP_CT_DIR_ORIGINAL) { | |
1195 | /* SNAT traps */ | |
1196 | map.from = NOCT1(&ct->tuplehash[dir].tuple.src.u3.ip); | |
1197 | map.to = NOCT1(&ct->tuplehash[!dir].tuple.dst.u3.ip); | |
1198 | } else { | |
1199 | /* DNAT replies */ | |
1200 | map.from = NOCT1(&ct->tuplehash[dir].tuple.src.u3.ip); | |
1201 | map.to = NOCT1(&ct->tuplehash[!dir].tuple.dst.u3.ip); | |
1202 | } | |
1203 | ||
1204 | if (map.from == map.to) | |
1205 | return NF_ACCEPT; | |
1206 | ||
1207 | if (!snmp_parse_mangle((unsigned char *)udph + sizeof(struct udphdr), | |
e905a9ed | 1208 | paylen, &map, &udph->check)) { |
e87cc472 | 1209 | net_warn_ratelimited("bsalg: parser failed\n"); |
807467c2 PM |
1210 | return NF_DROP; |
1211 | } | |
1212 | return NF_ACCEPT; | |
1213 | } | |
1214 | ||
1215 | /* We don't actually set up expectations, just adjust internal IP | |
1216 | * addresses if this is being NATted */ | |
3db05fea | 1217 | static int help(struct sk_buff *skb, unsigned int protoff, |
807467c2 PM |
1218 | struct nf_conn *ct, |
1219 | enum ip_conntrack_info ctinfo) | |
1220 | { | |
1221 | int dir = CTINFO2DIR(ctinfo); | |
1222 | unsigned int ret; | |
72b72949 JE |
1223 | const struct iphdr *iph = ip_hdr(skb); |
1224 | const struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl); | |
807467c2 PM |
1225 | |
1226 | /* SNMP replies and originating SNMP traps get mangled */ | |
1227 | if (udph->source == htons(SNMP_PORT) && dir != IP_CT_DIR_REPLY) | |
1228 | return NF_ACCEPT; | |
1229 | if (udph->dest == htons(SNMP_TRAP_PORT) && dir != IP_CT_DIR_ORIGINAL) | |
1230 | return NF_ACCEPT; | |
1231 | ||
1232 | /* No NAT? */ | |
1233 | if (!(ct->status & IPS_NAT_MASK)) | |
1234 | return NF_ACCEPT; | |
1235 | ||
1236 | /* | |
1237 | * Make sure the packet length is ok. So far, we were only guaranteed | |
1238 | * to have a valid length IP header plus 8 bytes, which means we have | |
1239 | * enough room for a UDP header. Just verify the UDP length field so we | |
1240 | * can mess around with the payload. | |
1241 | */ | |
3db05fea | 1242 | if (ntohs(udph->len) != skb->len - (iph->ihl << 2)) { |
e87cc472 JP |
1243 | net_warn_ratelimited("SNMP: dropping malformed packet src=%pI4 dst=%pI4\n", |
1244 | &iph->saddr, &iph->daddr); | |
807467c2 PM |
1245 | return NF_DROP; |
1246 | } | |
1247 | ||
3db05fea | 1248 | if (!skb_make_writable(skb, skb->len)) |
807467c2 PM |
1249 | return NF_DROP; |
1250 | ||
1251 | spin_lock_bh(&snmp_lock); | |
3db05fea | 1252 | ret = snmp_translate(ct, ctinfo, skb); |
807467c2 PM |
1253 | spin_unlock_bh(&snmp_lock); |
1254 | return ret; | |
1255 | } | |
1256 | ||
6002f266 PM |
1257 | static const struct nf_conntrack_expect_policy snmp_exp_policy = { |
1258 | .max_expected = 0, | |
1259 | .timeout = 180, | |
1260 | }; | |
1261 | ||
807467c2 | 1262 | static struct nf_conntrack_helper snmp_helper __read_mostly = { |
807467c2 PM |
1263 | .me = THIS_MODULE, |
1264 | .help = help, | |
6002f266 | 1265 | .expect_policy = &snmp_exp_policy, |
807467c2 PM |
1266 | .name = "snmp", |
1267 | .tuple.src.l3num = AF_INET, | |
09640e63 | 1268 | .tuple.src.u.udp.port = cpu_to_be16(SNMP_PORT), |
807467c2 | 1269 | .tuple.dst.protonum = IPPROTO_UDP, |
807467c2 PM |
1270 | }; |
1271 | ||
1272 | static struct nf_conntrack_helper snmp_trap_helper __read_mostly = { | |
807467c2 PM |
1273 | .me = THIS_MODULE, |
1274 | .help = help, | |
6002f266 | 1275 | .expect_policy = &snmp_exp_policy, |
807467c2 PM |
1276 | .name = "snmp_trap", |
1277 | .tuple.src.l3num = AF_INET, | |
09640e63 | 1278 | .tuple.src.u.udp.port = cpu_to_be16(SNMP_TRAP_PORT), |
807467c2 | 1279 | .tuple.dst.protonum = IPPROTO_UDP, |
807467c2 PM |
1280 | }; |
1281 | ||
1282 | /***************************************************************************** | |
1283 | * | |
1284 | * Module stuff. | |
1285 | * | |
1286 | *****************************************************************************/ | |
1287 | ||
1288 | static int __init nf_nat_snmp_basic_init(void) | |
1289 | { | |
1290 | int ret = 0; | |
1291 | ||
93557f53 | 1292 | BUG_ON(nf_nat_snmp_hook != NULL); |
a9b3cd7f | 1293 | RCU_INIT_POINTER(nf_nat_snmp_hook, help); |
93557f53 | 1294 | |
807467c2 PM |
1295 | ret = nf_conntrack_helper_register(&snmp_trap_helper); |
1296 | if (ret < 0) { | |
1297 | nf_conntrack_helper_unregister(&snmp_helper); | |
1298 | return ret; | |
1299 | } | |
1300 | return ret; | |
1301 | } | |
1302 | ||
1303 | static void __exit nf_nat_snmp_basic_fini(void) | |
1304 | { | |
a9b3cd7f | 1305 | RCU_INIT_POINTER(nf_nat_snmp_hook, NULL); |
807467c2 PM |
1306 | nf_conntrack_helper_unregister(&snmp_trap_helper); |
1307 | } | |
1308 | ||
1309 | module_init(nf_nat_snmp_basic_init); | |
1310 | module_exit(nf_nat_snmp_basic_fini); | |
1311 | ||
1312 | module_param(debug, int, 0600); |