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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 | |
a99421d9 | 37 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
807467c2 PM |
38 | * |
39 | * Author: James Morris <jmorris@intercode.com.au> | |
f229f6ce PM |
40 | * |
41 | * Copyright (c) 2006-2010 Patrick McHardy <kaber@trash.net> | |
807467c2 PM |
42 | */ |
43 | #include <linux/module.h> | |
44 | #include <linux/moduleparam.h> | |
45 | #include <linux/types.h> | |
46 | #include <linux/kernel.h> | |
5a0e3ad6 | 47 | #include <linux/slab.h> |
807467c2 PM |
48 | #include <linux/in.h> |
49 | #include <linux/ip.h> | |
50 | #include <linux/udp.h> | |
51 | #include <net/checksum.h> | |
52 | #include <net/udp.h> | |
53 | ||
54 | #include <net/netfilter/nf_nat.h> | |
6002f266 | 55 | #include <net/netfilter/nf_conntrack_expect.h> |
807467c2 PM |
56 | #include <net/netfilter/nf_conntrack_helper.h> |
57 | #include <net/netfilter/nf_nat_helper.h> | |
93557f53 | 58 | #include <linux/netfilter/nf_conntrack_snmp.h> |
807467c2 PM |
59 | |
60 | MODULE_LICENSE("GPL"); | |
61 | MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); | |
62 | MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway"); | |
63 | MODULE_ALIAS("ip_nat_snmp_basic"); | |
64 | ||
65 | #define SNMP_PORT 161 | |
66 | #define SNMP_TRAP_PORT 162 | |
e79ec50b | 67 | #define NOCT1(n) (*(u8 *)(n)) |
807467c2 PM |
68 | |
69 | static int debug; | |
70 | static DEFINE_SPINLOCK(snmp_lock); | |
71 | ||
72 | /* | |
73 | * Application layer address mapping mimics the NAT mapping, but | |
74 | * only for the first octet in this case (a more flexible system | |
75 | * can be implemented if needed). | |
76 | */ | |
77 | struct oct1_map | |
78 | { | |
79 | u_int8_t from; | |
80 | u_int8_t to; | |
81 | }; | |
82 | ||
83 | ||
84 | /***************************************************************************** | |
85 | * | |
86 | * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse) | |
87 | * | |
88 | *****************************************************************************/ | |
89 | ||
90 | /* Class */ | |
91 | #define ASN1_UNI 0 /* Universal */ | |
92 | #define ASN1_APL 1 /* Application */ | |
93 | #define ASN1_CTX 2 /* Context */ | |
94 | #define ASN1_PRV 3 /* Private */ | |
95 | ||
96 | /* Tag */ | |
97 | #define ASN1_EOC 0 /* End Of Contents */ | |
98 | #define ASN1_BOL 1 /* Boolean */ | |
99 | #define ASN1_INT 2 /* Integer */ | |
100 | #define ASN1_BTS 3 /* Bit String */ | |
101 | #define ASN1_OTS 4 /* Octet String */ | |
102 | #define ASN1_NUL 5 /* Null */ | |
103 | #define ASN1_OJI 6 /* Object Identifier */ | |
104 | #define ASN1_OJD 7 /* Object Description */ | |
105 | #define ASN1_EXT 8 /* External */ | |
106 | #define ASN1_SEQ 16 /* Sequence */ | |
107 | #define ASN1_SET 17 /* Set */ | |
108 | #define ASN1_NUMSTR 18 /* Numerical String */ | |
109 | #define ASN1_PRNSTR 19 /* Printable String */ | |
110 | #define ASN1_TEXSTR 20 /* Teletext String */ | |
111 | #define ASN1_VIDSTR 21 /* Video String */ | |
112 | #define ASN1_IA5STR 22 /* IA5 String */ | |
113 | #define ASN1_UNITIM 23 /* Universal Time */ | |
114 | #define ASN1_GENTIM 24 /* General Time */ | |
115 | #define ASN1_GRASTR 25 /* Graphical String */ | |
116 | #define ASN1_VISSTR 26 /* Visible String */ | |
117 | #define ASN1_GENSTR 27 /* General String */ | |
118 | ||
119 | /* Primitive / Constructed methods*/ | |
120 | #define ASN1_PRI 0 /* Primitive */ | |
121 | #define ASN1_CON 1 /* Constructed */ | |
122 | ||
123 | /* | |
124 | * Error codes. | |
125 | */ | |
126 | #define ASN1_ERR_NOERROR 0 | |
127 | #define ASN1_ERR_DEC_EMPTY 2 | |
128 | #define ASN1_ERR_DEC_EOC_MISMATCH 3 | |
129 | #define ASN1_ERR_DEC_LENGTH_MISMATCH 4 | |
130 | #define ASN1_ERR_DEC_BADVALUE 5 | |
131 | ||
132 | /* | |
133 | * ASN.1 context. | |
134 | */ | |
135 | struct asn1_ctx | |
136 | { | |
137 | int error; /* Error condition */ | |
138 | unsigned char *pointer; /* Octet just to be decoded */ | |
139 | unsigned char *begin; /* First octet */ | |
140 | unsigned char *end; /* Octet after last octet */ | |
141 | }; | |
142 | ||
143 | /* | |
144 | * Octet string (not null terminated) | |
145 | */ | |
146 | struct asn1_octstr | |
147 | { | |
148 | unsigned char *data; | |
149 | unsigned int len; | |
150 | }; | |
151 | ||
152 | static void asn1_open(struct asn1_ctx *ctx, | |
e905a9ed YH |
153 | unsigned char *buf, |
154 | unsigned int len) | |
807467c2 PM |
155 | { |
156 | ctx->begin = buf; | |
157 | ctx->end = buf + len; | |
158 | ctx->pointer = buf; | |
159 | ctx->error = ASN1_ERR_NOERROR; | |
160 | } | |
161 | ||
162 | static unsigned char asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch) | |
163 | { | |
164 | if (ctx->pointer >= ctx->end) { | |
165 | ctx->error = ASN1_ERR_DEC_EMPTY; | |
166 | return 0; | |
167 | } | |
168 | *ch = *(ctx->pointer)++; | |
169 | return 1; | |
170 | } | |
171 | ||
172 | static unsigned char asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag) | |
173 | { | |
174 | unsigned char ch; | |
175 | ||
176 | *tag = 0; | |
177 | ||
178 | do | |
179 | { | |
180 | if (!asn1_octet_decode(ctx, &ch)) | |
181 | return 0; | |
182 | *tag <<= 7; | |
183 | *tag |= ch & 0x7F; | |
184 | } while ((ch & 0x80) == 0x80); | |
185 | return 1; | |
186 | } | |
187 | ||
188 | static unsigned char asn1_id_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
189 | unsigned int *cls, |
190 | unsigned int *con, | |
191 | unsigned int *tag) | |
807467c2 PM |
192 | { |
193 | unsigned char ch; | |
194 | ||
195 | if (!asn1_octet_decode(ctx, &ch)) | |
196 | return 0; | |
197 | ||
198 | *cls = (ch & 0xC0) >> 6; | |
199 | *con = (ch & 0x20) >> 5; | |
200 | *tag = (ch & 0x1F); | |
201 | ||
202 | if (*tag == 0x1F) { | |
203 | if (!asn1_tag_decode(ctx, tag)) | |
204 | return 0; | |
205 | } | |
206 | return 1; | |
207 | } | |
208 | ||
209 | static unsigned char asn1_length_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
210 | unsigned int *def, |
211 | unsigned int *len) | |
807467c2 PM |
212 | { |
213 | unsigned char ch, cnt; | |
214 | ||
215 | if (!asn1_octet_decode(ctx, &ch)) | |
216 | return 0; | |
217 | ||
218 | if (ch == 0x80) | |
219 | *def = 0; | |
220 | else { | |
221 | *def = 1; | |
222 | ||
223 | if (ch < 0x80) | |
224 | *len = ch; | |
225 | else { | |
72b72949 | 226 | cnt = ch & 0x7F; |
807467c2 PM |
227 | *len = 0; |
228 | ||
229 | while (cnt > 0) { | |
230 | if (!asn1_octet_decode(ctx, &ch)) | |
231 | return 0; | |
232 | *len <<= 8; | |
233 | *len |= ch; | |
234 | cnt--; | |
235 | } | |
236 | } | |
237 | } | |
ddb2c435 CW |
238 | |
239 | /* don't trust len bigger than ctx buffer */ | |
240 | if (*len > ctx->end - ctx->pointer) | |
241 | return 0; | |
242 | ||
807467c2 PM |
243 | return 1; |
244 | } | |
245 | ||
246 | static unsigned char asn1_header_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
247 | unsigned char **eoc, |
248 | unsigned int *cls, | |
249 | unsigned int *con, | |
250 | unsigned int *tag) | |
807467c2 PM |
251 | { |
252 | unsigned int def, len; | |
253 | ||
254 | if (!asn1_id_decode(ctx, cls, con, tag)) | |
255 | return 0; | |
256 | ||
257 | def = len = 0; | |
258 | if (!asn1_length_decode(ctx, &def, &len)) | |
259 | return 0; | |
260 | ||
ddb2c435 CW |
261 | /* primitive shall be definite, indefinite shall be constructed */ |
262 | if (*con == ASN1_PRI && !def) | |
263 | return 0; | |
264 | ||
807467c2 PM |
265 | if (def) |
266 | *eoc = ctx->pointer + len; | |
267 | else | |
268 | *eoc = NULL; | |
269 | return 1; | |
270 | } | |
271 | ||
272 | static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc) | |
273 | { | |
274 | unsigned char ch; | |
275 | ||
06aa1072 | 276 | if (eoc == NULL) { |
807467c2 PM |
277 | if (!asn1_octet_decode(ctx, &ch)) |
278 | return 0; | |
279 | ||
280 | if (ch != 0x00) { | |
281 | ctx->error = ASN1_ERR_DEC_EOC_MISMATCH; | |
282 | return 0; | |
283 | } | |
284 | ||
285 | if (!asn1_octet_decode(ctx, &ch)) | |
286 | return 0; | |
287 | ||
288 | if (ch != 0x00) { | |
289 | ctx->error = ASN1_ERR_DEC_EOC_MISMATCH; | |
290 | return 0; | |
291 | } | |
292 | return 1; | |
293 | } else { | |
294 | if (ctx->pointer != eoc) { | |
295 | ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH; | |
296 | return 0; | |
297 | } | |
298 | return 1; | |
299 | } | |
300 | } | |
301 | ||
302 | static unsigned char asn1_null_decode(struct asn1_ctx *ctx, unsigned char *eoc) | |
303 | { | |
304 | ctx->pointer = eoc; | |
305 | return 1; | |
306 | } | |
307 | ||
308 | static unsigned char asn1_long_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
309 | unsigned char *eoc, |
310 | long *integer) | |
807467c2 PM |
311 | { |
312 | unsigned char ch; | |
313 | unsigned int len; | |
314 | ||
315 | if (!asn1_octet_decode(ctx, &ch)) | |
316 | return 0; | |
317 | ||
318 | *integer = (signed char) ch; | |
319 | len = 1; | |
320 | ||
321 | while (ctx->pointer < eoc) { | |
322 | if (++len > sizeof (long)) { | |
323 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
324 | return 0; | |
325 | } | |
326 | ||
327 | if (!asn1_octet_decode(ctx, &ch)) | |
328 | return 0; | |
329 | ||
330 | *integer <<= 8; | |
331 | *integer |= ch; | |
332 | } | |
333 | return 1; | |
334 | } | |
335 | ||
336 | static unsigned char asn1_uint_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
337 | unsigned char *eoc, |
338 | unsigned int *integer) | |
807467c2 PM |
339 | { |
340 | unsigned char ch; | |
341 | unsigned int len; | |
342 | ||
343 | if (!asn1_octet_decode(ctx, &ch)) | |
344 | return 0; | |
345 | ||
346 | *integer = ch; | |
347 | if (ch == 0) len = 0; | |
348 | else len = 1; | |
349 | ||
350 | while (ctx->pointer < eoc) { | |
351 | if (++len > sizeof (unsigned int)) { | |
352 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
353 | return 0; | |
354 | } | |
355 | ||
356 | if (!asn1_octet_decode(ctx, &ch)) | |
357 | return 0; | |
358 | ||
359 | *integer <<= 8; | |
360 | *integer |= ch; | |
361 | } | |
362 | return 1; | |
363 | } | |
364 | ||
365 | static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
366 | unsigned char *eoc, |
367 | unsigned long *integer) | |
807467c2 PM |
368 | { |
369 | unsigned char ch; | |
370 | unsigned int len; | |
371 | ||
372 | if (!asn1_octet_decode(ctx, &ch)) | |
373 | return 0; | |
374 | ||
375 | *integer = ch; | |
376 | if (ch == 0) len = 0; | |
377 | else len = 1; | |
378 | ||
379 | while (ctx->pointer < eoc) { | |
380 | if (++len > sizeof (unsigned long)) { | |
381 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
382 | return 0; | |
383 | } | |
384 | ||
385 | if (!asn1_octet_decode(ctx, &ch)) | |
386 | return 0; | |
387 | ||
388 | *integer <<= 8; | |
389 | *integer |= ch; | |
390 | } | |
391 | return 1; | |
392 | } | |
393 | ||
394 | static unsigned char asn1_octets_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
395 | unsigned char *eoc, |
396 | unsigned char **octets, | |
397 | unsigned int *len) | |
807467c2 PM |
398 | { |
399 | unsigned char *ptr; | |
400 | ||
401 | *len = 0; | |
402 | ||
403 | *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC); | |
0a9ee813 | 404 | if (*octets == NULL) |
807467c2 | 405 | return 0; |
807467c2 PM |
406 | |
407 | ptr = *octets; | |
408 | while (ctx->pointer < eoc) { | |
e3192690 | 409 | if (!asn1_octet_decode(ctx, ptr++)) { |
807467c2 PM |
410 | kfree(*octets); |
411 | *octets = NULL; | |
412 | return 0; | |
413 | } | |
414 | (*len)++; | |
415 | } | |
416 | return 1; | |
417 | } | |
418 | ||
419 | static unsigned char asn1_subid_decode(struct asn1_ctx *ctx, | |
e905a9ed | 420 | unsigned long *subid) |
807467c2 PM |
421 | { |
422 | unsigned char ch; | |
423 | ||
424 | *subid = 0; | |
425 | ||
426 | do { | |
427 | if (!asn1_octet_decode(ctx, &ch)) | |
428 | return 0; | |
429 | ||
430 | *subid <<= 7; | |
431 | *subid |= ch & 0x7F; | |
432 | } while ((ch & 0x80) == 0x80); | |
433 | return 1; | |
434 | } | |
435 | ||
436 | static unsigned char asn1_oid_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
437 | unsigned char *eoc, |
438 | unsigned long **oid, | |
439 | unsigned int *len) | |
807467c2 PM |
440 | { |
441 | unsigned long subid; | |
807467c2 | 442 | unsigned long *optr; |
252815b0 | 443 | size_t size; |
807467c2 PM |
444 | |
445 | size = eoc - ctx->pointer + 1; | |
ddb2c435 CW |
446 | |
447 | /* first subid actually encodes first two subids */ | |
448 | if (size < 2 || size > ULONG_MAX/sizeof(unsigned long)) | |
449 | return 0; | |
450 | ||
807467c2 | 451 | *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC); |
0a9ee813 | 452 | if (*oid == NULL) |
807467c2 | 453 | return 0; |
807467c2 PM |
454 | |
455 | optr = *oid; | |
456 | ||
457 | if (!asn1_subid_decode(ctx, &subid)) { | |
458 | kfree(*oid); | |
459 | *oid = NULL; | |
460 | return 0; | |
461 | } | |
462 | ||
463 | if (subid < 40) { | |
0c9a67d2 WC |
464 | optr[0] = 0; |
465 | optr[1] = subid; | |
807467c2 | 466 | } else if (subid < 80) { |
0c9a67d2 WC |
467 | optr[0] = 1; |
468 | optr[1] = subid - 40; | |
807467c2 | 469 | } else { |
0c9a67d2 WC |
470 | optr[0] = 2; |
471 | optr[1] = subid - 80; | |
807467c2 PM |
472 | } |
473 | ||
474 | *len = 2; | |
475 | optr += 2; | |
476 | ||
477 | while (ctx->pointer < eoc) { | |
478 | if (++(*len) > size) { | |
479 | ctx->error = ASN1_ERR_DEC_BADVALUE; | |
480 | kfree(*oid); | |
481 | *oid = NULL; | |
482 | return 0; | |
483 | } | |
484 | ||
485 | if (!asn1_subid_decode(ctx, optr++)) { | |
486 | kfree(*oid); | |
487 | *oid = NULL; | |
488 | return 0; | |
489 | } | |
490 | } | |
491 | return 1; | |
492 | } | |
493 | ||
494 | /***************************************************************************** | |
495 | * | |
496 | * SNMP decoding routines (gxsnmp author Dirk Wisse) | |
497 | * | |
498 | *****************************************************************************/ | |
499 | ||
500 | /* SNMP Versions */ | |
501 | #define SNMP_V1 0 | |
502 | #define SNMP_V2C 1 | |
503 | #define SNMP_V2 2 | |
504 | #define SNMP_V3 3 | |
505 | ||
506 | /* Default Sizes */ | |
507 | #define SNMP_SIZE_COMM 256 | |
508 | #define SNMP_SIZE_OBJECTID 128 | |
509 | #define SNMP_SIZE_BUFCHR 256 | |
510 | #define SNMP_SIZE_BUFINT 128 | |
511 | #define SNMP_SIZE_SMALLOBJECTID 16 | |
512 | ||
513 | /* Requests */ | |
514 | #define SNMP_PDU_GET 0 | |
515 | #define SNMP_PDU_NEXT 1 | |
516 | #define SNMP_PDU_RESPONSE 2 | |
517 | #define SNMP_PDU_SET 3 | |
518 | #define SNMP_PDU_TRAP1 4 | |
519 | #define SNMP_PDU_BULK 5 | |
520 | #define SNMP_PDU_INFORM 6 | |
521 | #define SNMP_PDU_TRAP2 7 | |
522 | ||
523 | /* Errors */ | |
524 | #define SNMP_NOERROR 0 | |
525 | #define SNMP_TOOBIG 1 | |
526 | #define SNMP_NOSUCHNAME 2 | |
527 | #define SNMP_BADVALUE 3 | |
528 | #define SNMP_READONLY 4 | |
529 | #define SNMP_GENERROR 5 | |
530 | #define SNMP_NOACCESS 6 | |
531 | #define SNMP_WRONGTYPE 7 | |
532 | #define SNMP_WRONGLENGTH 8 | |
533 | #define SNMP_WRONGENCODING 9 | |
534 | #define SNMP_WRONGVALUE 10 | |
535 | #define SNMP_NOCREATION 11 | |
536 | #define SNMP_INCONSISTENTVALUE 12 | |
537 | #define SNMP_RESOURCEUNAVAILABLE 13 | |
538 | #define SNMP_COMMITFAILED 14 | |
539 | #define SNMP_UNDOFAILED 15 | |
540 | #define SNMP_AUTHORIZATIONERROR 16 | |
541 | #define SNMP_NOTWRITABLE 17 | |
542 | #define SNMP_INCONSISTENTNAME 18 | |
543 | ||
544 | /* General SNMP V1 Traps */ | |
545 | #define SNMP_TRAP_COLDSTART 0 | |
546 | #define SNMP_TRAP_WARMSTART 1 | |
547 | #define SNMP_TRAP_LINKDOWN 2 | |
548 | #define SNMP_TRAP_LINKUP 3 | |
549 | #define SNMP_TRAP_AUTFAILURE 4 | |
550 | #define SNMP_TRAP_EQPNEIGHBORLOSS 5 | |
551 | #define SNMP_TRAP_ENTSPECIFIC 6 | |
552 | ||
553 | /* SNMPv1 Types */ | |
554 | #define SNMP_NULL 0 | |
555 | #define SNMP_INTEGER 1 /* l */ | |
556 | #define SNMP_OCTETSTR 2 /* c */ | |
557 | #define SNMP_DISPLAYSTR 2 /* c */ | |
558 | #define SNMP_OBJECTID 3 /* ul */ | |
559 | #define SNMP_IPADDR 4 /* uc */ | |
560 | #define SNMP_COUNTER 5 /* ul */ | |
561 | #define SNMP_GAUGE 6 /* ul */ | |
562 | #define SNMP_TIMETICKS 7 /* ul */ | |
563 | #define SNMP_OPAQUE 8 /* c */ | |
564 | ||
565 | /* Additional SNMPv2 Types */ | |
566 | #define SNMP_UINTEGER 5 /* ul */ | |
567 | #define SNMP_BITSTR 9 /* uc */ | |
568 | #define SNMP_NSAP 10 /* uc */ | |
569 | #define SNMP_COUNTER64 11 /* ul */ | |
570 | #define SNMP_NOSUCHOBJECT 12 | |
571 | #define SNMP_NOSUCHINSTANCE 13 | |
572 | #define SNMP_ENDOFMIBVIEW 14 | |
573 | ||
574 | union snmp_syntax | |
575 | { | |
576 | unsigned char uc[0]; /* 8 bit unsigned */ | |
577 | char c[0]; /* 8 bit signed */ | |
578 | unsigned long ul[0]; /* 32 bit unsigned */ | |
579 | long l[0]; /* 32 bit signed */ | |
580 | }; | |
581 | ||
582 | struct snmp_object | |
583 | { | |
584 | unsigned long *id; | |
585 | unsigned int id_len; | |
586 | unsigned short type; | |
587 | unsigned int syntax_len; | |
588 | union snmp_syntax syntax; | |
589 | }; | |
590 | ||
591 | struct snmp_request | |
592 | { | |
593 | unsigned long id; | |
594 | unsigned int error_status; | |
595 | unsigned int error_index; | |
596 | }; | |
597 | ||
598 | struct snmp_v1_trap | |
599 | { | |
600 | unsigned long *id; | |
601 | unsigned int id_len; | |
602 | unsigned long ip_address; /* pointer */ | |
603 | unsigned int general; | |
604 | unsigned int specific; | |
605 | unsigned long time; | |
606 | }; | |
607 | ||
608 | /* SNMP types */ | |
609 | #define SNMP_IPA 0 | |
610 | #define SNMP_CNT 1 | |
611 | #define SNMP_GGE 2 | |
612 | #define SNMP_TIT 3 | |
613 | #define SNMP_OPQ 4 | |
614 | #define SNMP_C64 6 | |
615 | ||
616 | /* SNMP errors */ | |
617 | #define SERR_NSO 0 | |
618 | #define SERR_NSI 1 | |
619 | #define SERR_EOM 2 | |
620 | ||
621 | static inline void mangle_address(unsigned char *begin, | |
e905a9ed YH |
622 | unsigned char *addr, |
623 | const struct oct1_map *map, | |
624 | __sum16 *check); | |
807467c2 PM |
625 | struct snmp_cnv |
626 | { | |
627 | unsigned int class; | |
628 | unsigned int tag; | |
629 | int syntax; | |
630 | }; | |
631 | ||
72b72949 | 632 | static const struct snmp_cnv snmp_conv[] = { |
807467c2 PM |
633 | {ASN1_UNI, ASN1_NUL, SNMP_NULL}, |
634 | {ASN1_UNI, ASN1_INT, SNMP_INTEGER}, | |
635 | {ASN1_UNI, ASN1_OTS, SNMP_OCTETSTR}, | |
636 | {ASN1_UNI, ASN1_OTS, SNMP_DISPLAYSTR}, | |
637 | {ASN1_UNI, ASN1_OJI, SNMP_OBJECTID}, | |
638 | {ASN1_APL, SNMP_IPA, SNMP_IPADDR}, | |
639 | {ASN1_APL, SNMP_CNT, SNMP_COUNTER}, /* Counter32 */ | |
640 | {ASN1_APL, SNMP_GGE, SNMP_GAUGE}, /* Gauge32 == Unsigned32 */ | |
641 | {ASN1_APL, SNMP_TIT, SNMP_TIMETICKS}, | |
642 | {ASN1_APL, SNMP_OPQ, SNMP_OPAQUE}, | |
643 | ||
644 | /* SNMPv2 data types and errors */ | |
645 | {ASN1_UNI, ASN1_BTS, SNMP_BITSTR}, | |
646 | {ASN1_APL, SNMP_C64, SNMP_COUNTER64}, | |
647 | {ASN1_CTX, SERR_NSO, SNMP_NOSUCHOBJECT}, | |
648 | {ASN1_CTX, SERR_NSI, SNMP_NOSUCHINSTANCE}, | |
649 | {ASN1_CTX, SERR_EOM, SNMP_ENDOFMIBVIEW}, | |
650 | {0, 0, -1} | |
651 | }; | |
652 | ||
653 | static unsigned char snmp_tag_cls2syntax(unsigned int tag, | |
e905a9ed YH |
654 | unsigned int cls, |
655 | unsigned short *syntax) | |
807467c2 | 656 | { |
72b72949 | 657 | const struct snmp_cnv *cnv; |
807467c2 PM |
658 | |
659 | cnv = snmp_conv; | |
660 | ||
661 | while (cnv->syntax != -1) { | |
662 | if (cnv->tag == tag && cnv->class == cls) { | |
663 | *syntax = cnv->syntax; | |
664 | return 1; | |
665 | } | |
666 | cnv++; | |
667 | } | |
668 | return 0; | |
669 | } | |
670 | ||
671 | static unsigned char snmp_object_decode(struct asn1_ctx *ctx, | |
e905a9ed | 672 | struct snmp_object **obj) |
807467c2 PM |
673 | { |
674 | unsigned int cls, con, tag, len, idlen; | |
675 | unsigned short type; | |
676 | unsigned char *eoc, *end, *p; | |
677 | unsigned long *lp, *id; | |
678 | unsigned long ul; | |
679 | long l; | |
680 | ||
681 | *obj = NULL; | |
682 | id = NULL; | |
683 | ||
684 | if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag)) | |
685 | return 0; | |
686 | ||
687 | if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) | |
688 | return 0; | |
689 | ||
690 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
691 | return 0; | |
692 | ||
693 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI) | |
694 | return 0; | |
695 | ||
696 | if (!asn1_oid_decode(ctx, end, &id, &idlen)) | |
697 | return 0; | |
698 | ||
699 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) { | |
700 | kfree(id); | |
701 | return 0; | |
702 | } | |
703 | ||
704 | if (con != ASN1_PRI) { | |
705 | kfree(id); | |
706 | return 0; | |
707 | } | |
708 | ||
709 | type = 0; | |
710 | if (!snmp_tag_cls2syntax(tag, cls, &type)) { | |
711 | kfree(id); | |
712 | return 0; | |
713 | } | |
714 | ||
715 | l = 0; | |
716 | switch (type) { | |
181b1e9c JP |
717 | case SNMP_INTEGER: |
718 | len = sizeof(long); | |
719 | if (!asn1_long_decode(ctx, end, &l)) { | |
720 | kfree(id); | |
721 | return 0; | |
722 | } | |
723 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
724 | if (*obj == NULL) { | |
725 | kfree(id); | |
181b1e9c JP |
726 | return 0; |
727 | } | |
728 | (*obj)->syntax.l[0] = l; | |
729 | break; | |
730 | case SNMP_OCTETSTR: | |
731 | case SNMP_OPAQUE: | |
732 | if (!asn1_octets_decode(ctx, end, &p, &len)) { | |
733 | kfree(id); | |
734 | return 0; | |
735 | } | |
736 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
737 | if (*obj == NULL) { | |
807467c2 | 738 | kfree(p); |
181b1e9c | 739 | kfree(id); |
181b1e9c JP |
740 | return 0; |
741 | } | |
742 | memcpy((*obj)->syntax.c, p, len); | |
743 | kfree(p); | |
744 | break; | |
745 | case SNMP_NULL: | |
746 | case SNMP_NOSUCHOBJECT: | |
747 | case SNMP_NOSUCHINSTANCE: | |
748 | case SNMP_ENDOFMIBVIEW: | |
749 | len = 0; | |
750 | *obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC); | |
751 | if (*obj == NULL) { | |
752 | kfree(id); | |
181b1e9c JP |
753 | return 0; |
754 | } | |
755 | if (!asn1_null_decode(ctx, end)) { | |
756 | kfree(id); | |
757 | kfree(*obj); | |
758 | *obj = NULL; | |
759 | return 0; | |
760 | } | |
761 | break; | |
762 | case SNMP_OBJECTID: | |
e3192690 | 763 | if (!asn1_oid_decode(ctx, end, &lp, &len)) { |
181b1e9c JP |
764 | kfree(id); |
765 | return 0; | |
766 | } | |
767 | len *= sizeof(unsigned long); | |
768 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
769 | if (*obj == NULL) { | |
807467c2 | 770 | kfree(lp); |
181b1e9c | 771 | kfree(id); |
181b1e9c JP |
772 | return 0; |
773 | } | |
774 | memcpy((*obj)->syntax.ul, lp, len); | |
775 | kfree(lp); | |
776 | break; | |
777 | case SNMP_IPADDR: | |
778 | if (!asn1_octets_decode(ctx, end, &p, &len)) { | |
779 | kfree(id); | |
780 | return 0; | |
781 | } | |
782 | if (len != 4) { | |
807467c2 | 783 | kfree(p); |
807467c2 PM |
784 | kfree(id); |
785 | return 0; | |
181b1e9c JP |
786 | } |
787 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
788 | if (*obj == NULL) { | |
789 | kfree(p); | |
790 | kfree(id); | |
181b1e9c JP |
791 | return 0; |
792 | } | |
793 | memcpy((*obj)->syntax.uc, p, len); | |
794 | kfree(p); | |
795 | break; | |
796 | case SNMP_COUNTER: | |
797 | case SNMP_GAUGE: | |
798 | case SNMP_TIMETICKS: | |
799 | len = sizeof(unsigned long); | |
800 | if (!asn1_ulong_decode(ctx, end, &ul)) { | |
801 | kfree(id); | |
802 | return 0; | |
803 | } | |
804 | *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC); | |
805 | if (*obj == NULL) { | |
806 | kfree(id); | |
181b1e9c JP |
807 | return 0; |
808 | } | |
809 | (*obj)->syntax.ul[0] = ul; | |
810 | break; | |
811 | default: | |
812 | kfree(id); | |
813 | return 0; | |
807467c2 PM |
814 | } |
815 | ||
816 | (*obj)->syntax_len = len; | |
817 | (*obj)->type = type; | |
818 | (*obj)->id = id; | |
819 | (*obj)->id_len = idlen; | |
820 | ||
821 | if (!asn1_eoc_decode(ctx, eoc)) { | |
822 | kfree(id); | |
823 | kfree(*obj); | |
824 | *obj = NULL; | |
825 | return 0; | |
826 | } | |
827 | return 1; | |
828 | } | |
829 | ||
830 | static unsigned char snmp_request_decode(struct asn1_ctx *ctx, | |
e905a9ed | 831 | struct snmp_request *request) |
807467c2 PM |
832 | { |
833 | unsigned int cls, con, tag; | |
834 | unsigned char *end; | |
835 | ||
836 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
837 | return 0; | |
838 | ||
839 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
840 | return 0; | |
841 | ||
842 | if (!asn1_ulong_decode(ctx, end, &request->id)) | |
843 | return 0; | |
844 | ||
845 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
846 | return 0; | |
847 | ||
848 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
849 | return 0; | |
850 | ||
851 | if (!asn1_uint_decode(ctx, end, &request->error_status)) | |
852 | return 0; | |
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_uint_decode(ctx, end, &request->error_index)) | |
861 | return 0; | |
862 | ||
863 | return 1; | |
864 | } | |
865 | ||
866 | /* | |
867 | * Fast checksum update for possibly oddly-aligned UDP byte, from the | |
868 | * code example in the draft. | |
869 | */ | |
870 | static void fast_csum(__sum16 *csum, | |
e905a9ed YH |
871 | const unsigned char *optr, |
872 | const unsigned char *nptr, | |
873 | int offset) | |
807467c2 PM |
874 | { |
875 | unsigned char s[4]; | |
876 | ||
877 | if (offset & 1) { | |
d6120b8a | 878 | s[0] = ~0; |
807467c2 | 879 | s[1] = ~*optr; |
d6120b8a | 880 | s[2] = 0; |
807467c2 PM |
881 | s[3] = *nptr; |
882 | } else { | |
807467c2 | 883 | s[0] = ~*optr; |
d6120b8a | 884 | s[1] = ~0; |
807467c2 | 885 | s[2] = *nptr; |
d6120b8a | 886 | s[3] = 0; |
807467c2 PM |
887 | } |
888 | ||
889 | *csum = csum_fold(csum_partial(s, 4, ~csum_unfold(*csum))); | |
890 | } | |
891 | ||
892 | /* | |
893 | * Mangle IP address. | |
894 | * - begin points to the start of the snmp messgae | |
895 | * - addr points to the start of the address | |
896 | */ | |
897 | static inline void mangle_address(unsigned char *begin, | |
e905a9ed YH |
898 | unsigned char *addr, |
899 | const struct oct1_map *map, | |
900 | __sum16 *check) | |
807467c2 PM |
901 | { |
902 | if (map->from == NOCT1(addr)) { | |
903 | u_int32_t old; | |
904 | ||
905 | if (debug) | |
72b72949 | 906 | memcpy(&old, addr, sizeof(old)); |
807467c2 PM |
907 | |
908 | *addr = map->to; | |
909 | ||
910 | /* Update UDP checksum if being used */ | |
911 | if (*check) { | |
912 | fast_csum(check, | |
e905a9ed | 913 | &map->from, &map->to, addr - begin); |
807467c2 PM |
914 | |
915 | } | |
916 | ||
917 | if (debug) | |
cffee385 HH |
918 | printk(KERN_DEBUG "bsalg: mapped %pI4 to %pI4\n", |
919 | &old, addr); | |
807467c2 PM |
920 | } |
921 | } | |
922 | ||
923 | static unsigned char snmp_trap_decode(struct asn1_ctx *ctx, | |
e905a9ed YH |
924 | struct snmp_v1_trap *trap, |
925 | const struct oct1_map *map, | |
926 | __sum16 *check) | |
807467c2 PM |
927 | { |
928 | unsigned int cls, con, tag, len; | |
929 | unsigned char *end; | |
930 | ||
931 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
932 | return 0; | |
933 | ||
934 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI) | |
935 | return 0; | |
936 | ||
937 | if (!asn1_oid_decode(ctx, end, &trap->id, &trap->id_len)) | |
938 | return 0; | |
939 | ||
940 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
941 | goto err_id_free; | |
942 | ||
943 | if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_IPA) || | |
944 | (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_OTS))) | |
945 | goto err_id_free; | |
946 | ||
947 | if (!asn1_octets_decode(ctx, end, (unsigned char **)&trap->ip_address, &len)) | |
948 | goto err_id_free; | |
949 | ||
950 | /* IPv4 only */ | |
951 | if (len != 4) | |
952 | goto err_addr_free; | |
953 | ||
954 | mangle_address(ctx->begin, ctx->pointer - 4, map, check); | |
955 | ||
956 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
957 | goto err_addr_free; | |
958 | ||
959 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
960 | goto err_addr_free; | |
961 | ||
962 | if (!asn1_uint_decode(ctx, end, &trap->general)) | |
963 | goto err_addr_free; | |
964 | ||
965 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
966 | goto err_addr_free; | |
967 | ||
968 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
969 | goto err_addr_free; | |
970 | ||
971 | if (!asn1_uint_decode(ctx, end, &trap->specific)) | |
972 | goto err_addr_free; | |
973 | ||
974 | if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) | |
975 | goto err_addr_free; | |
976 | ||
977 | if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_TIT) || | |
978 | (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_INT))) | |
979 | goto err_addr_free; | |
980 | ||
981 | if (!asn1_ulong_decode(ctx, end, &trap->time)) | |
982 | goto err_addr_free; | |
983 | ||
984 | return 1; | |
985 | ||
986 | err_addr_free: | |
987 | kfree((unsigned long *)trap->ip_address); | |
988 | ||
989 | err_id_free: | |
990 | kfree(trap->id); | |
991 | ||
992 | return 0; | |
993 | } | |
994 | ||
995 | /***************************************************************************** | |
996 | * | |
997 | * Misc. routines | |
998 | * | |
999 | *****************************************************************************/ | |
1000 | ||
72b72949 | 1001 | static void hex_dump(const unsigned char *buf, size_t len) |
807467c2 PM |
1002 | { |
1003 | size_t i; | |
1004 | ||
1005 | for (i = 0; i < len; i++) { | |
1006 | if (i && !(i % 16)) | |
1007 | printk("\n"); | |
1008 | printk("%02x ", *(buf + i)); | |
1009 | } | |
1010 | printk("\n"); | |
1011 | } | |
1012 | ||
1013 | /* | |
1014 | * Parse and mangle SNMP message according to mapping. | |
1015 | * (And this is the fucking 'basic' method). | |
1016 | */ | |
1017 | static int snmp_parse_mangle(unsigned char *msg, | |
e905a9ed YH |
1018 | u_int16_t len, |
1019 | const struct oct1_map *map, | |
1020 | __sum16 *check) | |
807467c2 PM |
1021 | { |
1022 | unsigned char *eoc, *end; | |
1023 | unsigned int cls, con, tag, vers, pdutype; | |
1024 | struct asn1_ctx ctx; | |
1025 | struct asn1_octstr comm; | |
71c3ebfd | 1026 | struct snmp_object *obj; |
807467c2 PM |
1027 | |
1028 | if (debug > 1) | |
1029 | hex_dump(msg, len); | |
1030 | ||
1031 | asn1_open(&ctx, msg, len); | |
1032 | ||
1033 | /* | |
1034 | * Start of SNMP message. | |
1035 | */ | |
1036 | if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag)) | |
1037 | return 0; | |
1038 | if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) | |
1039 | return 0; | |
1040 | ||
1041 | /* | |
1042 | * Version 1 or 2 handled. | |
1043 | */ | |
1044 | if (!asn1_header_decode(&ctx, &end, &cls, &con, &tag)) | |
1045 | return 0; | |
1046 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) | |
1047 | return 0; | |
1048 | if (!asn1_uint_decode (&ctx, end, &vers)) | |
1049 | return 0; | |
1050 | if (debug > 1) | |
09605cc1 | 1051 | pr_debug("bsalg: snmp version: %u\n", vers + 1); |
807467c2 PM |
1052 | if (vers > 1) |
1053 | return 1; | |
1054 | ||
1055 | /* | |
1056 | * Community. | |
1057 | */ | |
1058 | if (!asn1_header_decode (&ctx, &end, &cls, &con, &tag)) | |
1059 | return 0; | |
1060 | if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OTS) | |
1061 | return 0; | |
1062 | if (!asn1_octets_decode(&ctx, end, &comm.data, &comm.len)) | |
1063 | return 0; | |
1064 | if (debug > 1) { | |
1065 | unsigned int i; | |
1066 | ||
09605cc1 | 1067 | pr_debug("bsalg: community: "); |
807467c2 | 1068 | for (i = 0; i < comm.len; i++) |
09605cc1 BS |
1069 | pr_cont("%c", comm.data[i]); |
1070 | pr_cont("\n"); | |
807467c2 PM |
1071 | } |
1072 | kfree(comm.data); | |
1073 | ||
1074 | /* | |
1075 | * PDU type | |
1076 | */ | |
1077 | if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &pdutype)) | |
1078 | return 0; | |
1079 | if (cls != ASN1_CTX || con != ASN1_CON) | |
1080 | return 0; | |
1081 | if (debug > 1) { | |
72b72949 | 1082 | static const unsigned char *const pdus[] = { |
807467c2 PM |
1083 | [SNMP_PDU_GET] = "get", |
1084 | [SNMP_PDU_NEXT] = "get-next", | |
1085 | [SNMP_PDU_RESPONSE] = "response", | |
1086 | [SNMP_PDU_SET] = "set", | |
1087 | [SNMP_PDU_TRAP1] = "trapv1", | |
1088 | [SNMP_PDU_BULK] = "bulk", | |
1089 | [SNMP_PDU_INFORM] = "inform", | |
1090 | [SNMP_PDU_TRAP2] = "trapv2" | |
1091 | }; | |
1092 | ||
1093 | if (pdutype > SNMP_PDU_TRAP2) | |
09605cc1 | 1094 | pr_debug("bsalg: bad pdu type %u\n", pdutype); |
807467c2 | 1095 | else |
09605cc1 | 1096 | pr_debug("bsalg: pdu: %s\n", pdus[pdutype]); |
807467c2 PM |
1097 | } |
1098 | if (pdutype != SNMP_PDU_RESPONSE && | |
1099 | pdutype != SNMP_PDU_TRAP1 && pdutype != SNMP_PDU_TRAP2) | |
1100 | return 1; | |
1101 | ||
1102 | /* | |
1103 | * Request header or v1 trap | |
1104 | */ | |
1105 | if (pdutype == SNMP_PDU_TRAP1) { | |
1106 | struct snmp_v1_trap trap; | |
1107 | unsigned char ret = snmp_trap_decode(&ctx, &trap, map, check); | |
1108 | ||
1109 | if (ret) { | |
1110 | kfree(trap.id); | |
1111 | kfree((unsigned long *)trap.ip_address); | |
1112 | } else | |
1113 | return ret; | |
1114 | ||
1115 | } else { | |
1116 | struct snmp_request req; | |
1117 | ||
1118 | if (!snmp_request_decode(&ctx, &req)) | |
1119 | return 0; | |
1120 | ||
1121 | if (debug > 1) | |
09605cc1 | 1122 | pr_debug("bsalg: request: id=0x%lx error_status=%u " |
807467c2 PM |
1123 | "error_index=%u\n", req.id, req.error_status, |
1124 | req.error_index); | |
1125 | } | |
1126 | ||
1127 | /* | |
1128 | * Loop through objects, look for IP addresses to mangle. | |
1129 | */ | |
1130 | if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag)) | |
1131 | return 0; | |
1132 | ||
1133 | if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) | |
1134 | return 0; | |
1135 | ||
807467c2 PM |
1136 | while (!asn1_eoc_decode(&ctx, eoc)) { |
1137 | unsigned int i; | |
1138 | ||
71c3ebfd JL |
1139 | if (!snmp_object_decode(&ctx, &obj)) { |
1140 | if (obj) { | |
1141 | kfree(obj->id); | |
1142 | kfree(obj); | |
807467c2 | 1143 | } |
807467c2 PM |
1144 | return 0; |
1145 | } | |
1146 | ||
1147 | if (debug > 1) { | |
09605cc1 | 1148 | pr_debug("bsalg: object: "); |
71c3ebfd | 1149 | for (i = 0; i < obj->id_len; i++) { |
807467c2 | 1150 | if (i > 0) |
09605cc1 BS |
1151 | pr_cont("."); |
1152 | pr_cont("%lu", obj->id[i]); | |
807467c2 | 1153 | } |
09605cc1 | 1154 | pr_cont(": type=%u\n", obj->type); |
807467c2 PM |
1155 | |
1156 | } | |
1157 | ||
71c3ebfd | 1158 | if (obj->type == SNMP_IPADDR) |
c8d71d08 | 1159 | mangle_address(ctx.begin, ctx.pointer - 4, map, check); |
807467c2 | 1160 | |
71c3ebfd JL |
1161 | kfree(obj->id); |
1162 | kfree(obj); | |
807467c2 | 1163 | } |
807467c2 PM |
1164 | |
1165 | if (!asn1_eoc_decode(&ctx, eoc)) | |
1166 | return 0; | |
1167 | ||
1168 | return 1; | |
1169 | } | |
1170 | ||
1171 | /***************************************************************************** | |
1172 | * | |
1173 | * NAT routines. | |
1174 | * | |
1175 | *****************************************************************************/ | |
1176 | ||
1177 | /* | |
1178 | * SNMP translation routine. | |
1179 | */ | |
1180 | static int snmp_translate(struct nf_conn *ct, | |
e905a9ed | 1181 | enum ip_conntrack_info ctinfo, |
3db05fea | 1182 | struct sk_buff *skb) |
807467c2 | 1183 | { |
3db05fea | 1184 | struct iphdr *iph = ip_hdr(skb); |
807467c2 PM |
1185 | struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl); |
1186 | u_int16_t udplen = ntohs(udph->len); | |
1187 | u_int16_t paylen = udplen - sizeof(struct udphdr); | |
1188 | int dir = CTINFO2DIR(ctinfo); | |
1189 | struct oct1_map map; | |
1190 | ||
1191 | /* | |
1192 | * Determine mappping for application layer addresses based | |
1193 | * on NAT manipulations for the packet. | |
1194 | */ | |
1195 | if (dir == IP_CT_DIR_ORIGINAL) { | |
1196 | /* SNAT traps */ | |
1197 | map.from = NOCT1(&ct->tuplehash[dir].tuple.src.u3.ip); | |
1198 | map.to = NOCT1(&ct->tuplehash[!dir].tuple.dst.u3.ip); | |
1199 | } else { | |
1200 | /* DNAT replies */ | |
2b7a79ba FLB |
1201 | map.from = NOCT1(&ct->tuplehash[!dir].tuple.src.u3.ip); |
1202 | map.to = NOCT1(&ct->tuplehash[dir].tuple.dst.u3.ip); | |
807467c2 PM |
1203 | } |
1204 | ||
1205 | if (map.from == map.to) | |
1206 | return NF_ACCEPT; | |
1207 | ||
1208 | if (!snmp_parse_mangle((unsigned char *)udph + sizeof(struct udphdr), | |
e905a9ed | 1209 | paylen, &map, &udph->check)) { |
e87cc472 | 1210 | net_warn_ratelimited("bsalg: parser failed\n"); |
807467c2 PM |
1211 | return NF_DROP; |
1212 | } | |
1213 | return NF_ACCEPT; | |
1214 | } | |
1215 | ||
1216 | /* We don't actually set up expectations, just adjust internal IP | |
1217 | * addresses if this is being NATted */ | |
3db05fea | 1218 | static int help(struct sk_buff *skb, unsigned int protoff, |
807467c2 PM |
1219 | struct nf_conn *ct, |
1220 | enum ip_conntrack_info ctinfo) | |
1221 | { | |
1222 | int dir = CTINFO2DIR(ctinfo); | |
1223 | unsigned int ret; | |
72b72949 JE |
1224 | const struct iphdr *iph = ip_hdr(skb); |
1225 | const struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl); | |
807467c2 PM |
1226 | |
1227 | /* SNMP replies and originating SNMP traps get mangled */ | |
1228 | if (udph->source == htons(SNMP_PORT) && dir != IP_CT_DIR_REPLY) | |
1229 | return NF_ACCEPT; | |
1230 | if (udph->dest == htons(SNMP_TRAP_PORT) && dir != IP_CT_DIR_ORIGINAL) | |
1231 | return NF_ACCEPT; | |
1232 | ||
1233 | /* No NAT? */ | |
1234 | if (!(ct->status & IPS_NAT_MASK)) | |
1235 | return NF_ACCEPT; | |
1236 | ||
1237 | /* | |
1238 | * Make sure the packet length is ok. So far, we were only guaranteed | |
1239 | * to have a valid length IP header plus 8 bytes, which means we have | |
1240 | * enough room for a UDP header. Just verify the UDP length field so we | |
1241 | * can mess around with the payload. | |
1242 | */ | |
3db05fea | 1243 | if (ntohs(udph->len) != skb->len - (iph->ihl << 2)) { |
e87cc472 JP |
1244 | net_warn_ratelimited("SNMP: dropping malformed packet src=%pI4 dst=%pI4\n", |
1245 | &iph->saddr, &iph->daddr); | |
807467c2 PM |
1246 | return NF_DROP; |
1247 | } | |
1248 | ||
3db05fea | 1249 | if (!skb_make_writable(skb, skb->len)) |
807467c2 PM |
1250 | return NF_DROP; |
1251 | ||
1252 | spin_lock_bh(&snmp_lock); | |
3db05fea | 1253 | ret = snmp_translate(ct, ctinfo, skb); |
807467c2 PM |
1254 | spin_unlock_bh(&snmp_lock); |
1255 | return ret; | |
1256 | } | |
1257 | ||
6002f266 PM |
1258 | static const struct nf_conntrack_expect_policy snmp_exp_policy = { |
1259 | .max_expected = 0, | |
1260 | .timeout = 180, | |
1261 | }; | |
1262 | ||
807467c2 | 1263 | static struct nf_conntrack_helper snmp_trap_helper __read_mostly = { |
807467c2 PM |
1264 | .me = THIS_MODULE, |
1265 | .help = help, | |
6002f266 | 1266 | .expect_policy = &snmp_exp_policy, |
807467c2 PM |
1267 | .name = "snmp_trap", |
1268 | .tuple.src.l3num = AF_INET, | |
09640e63 | 1269 | .tuple.src.u.udp.port = cpu_to_be16(SNMP_TRAP_PORT), |
807467c2 | 1270 | .tuple.dst.protonum = IPPROTO_UDP, |
807467c2 PM |
1271 | }; |
1272 | ||
1273 | /***************************************************************************** | |
1274 | * | |
1275 | * Module stuff. | |
1276 | * | |
1277 | *****************************************************************************/ | |
1278 | ||
1279 | static int __init nf_nat_snmp_basic_init(void) | |
1280 | { | |
93557f53 | 1281 | BUG_ON(nf_nat_snmp_hook != NULL); |
a9b3cd7f | 1282 | RCU_INIT_POINTER(nf_nat_snmp_hook, help); |
93557f53 | 1283 | |
75c689dc | 1284 | return nf_conntrack_helper_register(&snmp_trap_helper); |
807467c2 PM |
1285 | } |
1286 | ||
1287 | static void __exit nf_nat_snmp_basic_fini(void) | |
1288 | { | |
a9b3cd7f | 1289 | RCU_INIT_POINTER(nf_nat_snmp_hook, NULL); |
3b7dabf0 | 1290 | synchronize_rcu(); |
807467c2 PM |
1291 | nf_conntrack_helper_unregister(&snmp_trap_helper); |
1292 | } | |
1293 | ||
1294 | module_init(nf_nat_snmp_basic_init); | |
1295 | module_exit(nf_nat_snmp_basic_fini); | |
1296 | ||
1297 | module_param(debug, int, 0600); |