4 * Basic SNMP Application Layer Gateway
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.
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.
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.
18 * Currently, only SNMPv1 and SNMPv2 are supported.
20 * More information on ALG and associated issues can be found in
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.
26 * Copyright (c) 2000 RP Internet (www.rpi.net.au).
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, see <http://www.gnu.org/licenses/>.
39 * Author: James Morris <jmorris@intercode.com.au>
41 * Copyright (c) 2006-2010 Patrick McHardy <kaber@trash.net>
43 #include <linux/module.h>
44 #include <linux/moduleparam.h>
45 #include <linux/types.h>
46 #include <linux/kernel.h>
47 #include <linux/slab.h>
50 #include <linux/udp.h>
51 #include <net/checksum.h>
54 #include <net/netfilter/nf_nat.h>
55 #include <net/netfilter/nf_conntrack_expect.h>
56 #include <net/netfilter/nf_conntrack_helper.h>
57 #include <net/netfilter/nf_nat_helper.h>
58 #include <linux/netfilter/nf_conntrack_snmp.h>
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");
66 #define SNMP_TRAP_PORT 162
67 #define NOCT1(n) (*(u8 *)(n))
70 static DEFINE_SPINLOCK(snmp_lock
);
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).
84 /*****************************************************************************
86 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
88 *****************************************************************************/
91 #define ASN1_UNI 0 /* Universal */
92 #define ASN1_APL 1 /* Application */
93 #define ASN1_CTX 2 /* Context */
94 #define ASN1_PRV 3 /* Private */
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 */
119 /* Primitive / Constructed methods*/
120 #define ASN1_PRI 0 /* Primitive */
121 #define ASN1_CON 1 /* Constructed */
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
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 */
144 * Octet string (not null terminated)
152 static void asn1_open(struct asn1_ctx
*ctx
,
157 ctx
->end
= buf
+ len
;
159 ctx
->error
= ASN1_ERR_NOERROR
;
162 static unsigned char asn1_octet_decode(struct asn1_ctx
*ctx
, unsigned char *ch
)
164 if (ctx
->pointer
>= ctx
->end
) {
165 ctx
->error
= ASN1_ERR_DEC_EMPTY
;
168 *ch
= *(ctx
->pointer
)++;
172 static unsigned char asn1_tag_decode(struct asn1_ctx
*ctx
, unsigned int *tag
)
180 if (!asn1_octet_decode(ctx
, &ch
))
184 } while ((ch
& 0x80) == 0x80);
188 static unsigned char asn1_id_decode(struct asn1_ctx
*ctx
,
195 if (!asn1_octet_decode(ctx
, &ch
))
198 *cls
= (ch
& 0xC0) >> 6;
199 *con
= (ch
& 0x20) >> 5;
203 if (!asn1_tag_decode(ctx
, tag
))
209 static unsigned char asn1_length_decode(struct asn1_ctx
*ctx
,
213 unsigned char ch
, cnt
;
215 if (!asn1_octet_decode(ctx
, &ch
))
230 if (!asn1_octet_decode(ctx
, &ch
))
239 /* don't trust len bigger than ctx buffer */
240 if (*len
> ctx
->end
- ctx
->pointer
)
246 static unsigned char asn1_header_decode(struct asn1_ctx
*ctx
,
252 unsigned int def
, len
;
254 if (!asn1_id_decode(ctx
, cls
, con
, tag
))
258 if (!asn1_length_decode(ctx
, &def
, &len
))
261 /* primitive shall be definite, indefinite shall be constructed */
262 if (*con
== ASN1_PRI
&& !def
)
266 *eoc
= ctx
->pointer
+ len
;
272 static unsigned char asn1_eoc_decode(struct asn1_ctx
*ctx
, unsigned char *eoc
)
277 if (!asn1_octet_decode(ctx
, &ch
))
281 ctx
->error
= ASN1_ERR_DEC_EOC_MISMATCH
;
285 if (!asn1_octet_decode(ctx
, &ch
))
289 ctx
->error
= ASN1_ERR_DEC_EOC_MISMATCH
;
294 if (ctx
->pointer
!= eoc
) {
295 ctx
->error
= ASN1_ERR_DEC_LENGTH_MISMATCH
;
302 static unsigned char asn1_null_decode(struct asn1_ctx
*ctx
, unsigned char *eoc
)
308 static unsigned char asn1_long_decode(struct asn1_ctx
*ctx
,
315 if (!asn1_octet_decode(ctx
, &ch
))
318 *integer
= (signed char) ch
;
321 while (ctx
->pointer
< eoc
) {
322 if (++len
> sizeof (long)) {
323 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
327 if (!asn1_octet_decode(ctx
, &ch
))
336 static unsigned char asn1_uint_decode(struct asn1_ctx
*ctx
,
338 unsigned int *integer
)
343 if (!asn1_octet_decode(ctx
, &ch
))
347 if (ch
== 0) len
= 0;
350 while (ctx
->pointer
< eoc
) {
351 if (++len
> sizeof (unsigned int)) {
352 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
356 if (!asn1_octet_decode(ctx
, &ch
))
365 static unsigned char asn1_ulong_decode(struct asn1_ctx
*ctx
,
367 unsigned long *integer
)
372 if (!asn1_octet_decode(ctx
, &ch
))
376 if (ch
== 0) len
= 0;
379 while (ctx
->pointer
< eoc
) {
380 if (++len
> sizeof (unsigned long)) {
381 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
385 if (!asn1_octet_decode(ctx
, &ch
))
394 static unsigned char asn1_octets_decode(struct asn1_ctx
*ctx
,
396 unsigned char **octets
,
403 *octets
= kmalloc(eoc
- ctx
->pointer
, GFP_ATOMIC
);
408 while (ctx
->pointer
< eoc
) {
409 if (!asn1_octet_decode(ctx
, ptr
++)) {
419 static unsigned char asn1_subid_decode(struct asn1_ctx
*ctx
,
420 unsigned long *subid
)
427 if (!asn1_octet_decode(ctx
, &ch
))
432 } while ((ch
& 0x80) == 0x80);
436 static unsigned char asn1_oid_decode(struct asn1_ctx
*ctx
,
445 size
= eoc
- ctx
->pointer
+ 1;
447 /* first subid actually encodes first two subids */
448 if (size
< 2 || size
> ULONG_MAX
/sizeof(unsigned long))
451 *oid
= kmalloc(size
* sizeof(unsigned long), GFP_ATOMIC
);
457 if (!asn1_subid_decode(ctx
, &subid
)) {
466 } else if (subid
< 80) {
468 optr
[1] = subid
- 40;
471 optr
[1] = subid
- 80;
477 while (ctx
->pointer
< eoc
) {
478 if (++(*len
) > size
) {
479 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
485 if (!asn1_subid_decode(ctx
, optr
++)) {
494 /*****************************************************************************
496 * SNMP decoding routines (gxsnmp author Dirk Wisse)
498 *****************************************************************************/
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
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
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
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
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 */
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
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 */
587 unsigned int syntax_len
;
588 union snmp_syntax syntax
;
594 unsigned int error_status
;
595 unsigned int error_index
;
602 unsigned long ip_address
; /* pointer */
603 unsigned int general
;
604 unsigned int specific
;
621 static inline void mangle_address(unsigned char *begin
,
623 const struct oct1_map
*map
,
632 static const struct snmp_cnv snmp_conv
[] = {
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
},
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
},
653 static unsigned char snmp_tag_cls2syntax(unsigned int tag
,
655 unsigned short *syntax
)
657 const struct snmp_cnv
*cnv
;
661 while (cnv
->syntax
!= -1) {
662 if (cnv
->tag
== tag
&& cnv
->class == cls
) {
663 *syntax
= cnv
->syntax
;
671 static unsigned char snmp_object_decode(struct asn1_ctx
*ctx
,
672 struct snmp_object
**obj
)
674 unsigned int cls
, con
, tag
, len
, idlen
;
676 unsigned char *eoc
, *end
, *p
;
677 unsigned long *lp
, *id
;
684 if (!asn1_header_decode(ctx
, &eoc
, &cls
, &con
, &tag
))
687 if (cls
!= ASN1_UNI
|| con
!= ASN1_CON
|| tag
!= ASN1_SEQ
)
690 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
693 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_OJI
)
696 if (!asn1_oid_decode(ctx
, end
, &id
, &idlen
))
699 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
)) {
704 if (con
!= ASN1_PRI
) {
710 if (!snmp_tag_cls2syntax(tag
, cls
, &type
)) {
719 if (!asn1_long_decode(ctx
, end
, &l
)) {
723 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
728 (*obj
)->syntax
.l
[0] = l
;
732 if (!asn1_octets_decode(ctx
, end
, &p
, &len
)) {
736 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
742 memcpy((*obj
)->syntax
.c
, p
, len
);
746 case SNMP_NOSUCHOBJECT
:
747 case SNMP_NOSUCHINSTANCE
:
748 case SNMP_ENDOFMIBVIEW
:
750 *obj
= kmalloc(sizeof(struct snmp_object
), GFP_ATOMIC
);
755 if (!asn1_null_decode(ctx
, end
)) {
763 if (!asn1_oid_decode(ctx
, end
, &lp
, &len
)) {
767 len
*= sizeof(unsigned long);
768 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
774 memcpy((*obj
)->syntax
.ul
, lp
, len
);
778 if (!asn1_octets_decode(ctx
, end
, &p
, &len
)) {
787 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
793 memcpy((*obj
)->syntax
.uc
, p
, len
);
799 len
= sizeof(unsigned long);
800 if (!asn1_ulong_decode(ctx
, end
, &ul
)) {
804 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
809 (*obj
)->syntax
.ul
[0] = ul
;
816 (*obj
)->syntax_len
= len
;
819 (*obj
)->id_len
= idlen
;
821 if (!asn1_eoc_decode(ctx
, eoc
)) {
830 static unsigned char snmp_request_decode(struct asn1_ctx
*ctx
,
831 struct snmp_request
*request
)
833 unsigned int cls
, con
, tag
;
836 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
839 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
842 if (!asn1_ulong_decode(ctx
, end
, &request
->id
))
845 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
848 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
851 if (!asn1_uint_decode(ctx
, end
, &request
->error_status
))
854 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
857 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
860 if (!asn1_uint_decode(ctx
, end
, &request
->error_index
))
867 * Fast checksum update for possibly oddly-aligned UDP byte, from the
868 * code example in the draft.
870 static void fast_csum(__sum16
*csum
,
871 const unsigned char *optr
,
872 const unsigned char *nptr
,
889 *csum
= csum_fold(csum_partial(s
, 4, ~csum_unfold(*csum
)));
894 * - begin points to the start of the snmp messgae
895 * - addr points to the start of the address
897 static inline void mangle_address(unsigned char *begin
,
899 const struct oct1_map
*map
,
902 if (map
->from
== NOCT1(addr
)) {
906 memcpy(&old
, addr
, sizeof(old
));
910 /* Update UDP checksum if being used */
913 &map
->from
, &map
->to
, addr
- begin
);
918 printk(KERN_DEBUG
"bsalg: mapped %pI4 to %pI4\n",
923 static unsigned char snmp_trap_decode(struct asn1_ctx
*ctx
,
924 struct snmp_v1_trap
*trap
,
925 const struct oct1_map
*map
,
928 unsigned int cls
, con
, tag
, len
;
931 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
934 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_OJI
)
937 if (!asn1_oid_decode(ctx
, end
, &trap
->id
, &trap
->id_len
))
940 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
943 if (!((cls
== ASN1_APL
&& con
== ASN1_PRI
&& tag
== SNMP_IPA
) ||
944 (cls
== ASN1_UNI
&& con
== ASN1_PRI
&& tag
== ASN1_OTS
)))
947 if (!asn1_octets_decode(ctx
, end
, (unsigned char **)&trap
->ip_address
, &len
))
954 mangle_address(ctx
->begin
, ctx
->pointer
- 4, map
, check
);
956 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
959 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
962 if (!asn1_uint_decode(ctx
, end
, &trap
->general
))
965 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
968 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
971 if (!asn1_uint_decode(ctx
, end
, &trap
->specific
))
974 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
977 if (!((cls
== ASN1_APL
&& con
== ASN1_PRI
&& tag
== SNMP_TIT
) ||
978 (cls
== ASN1_UNI
&& con
== ASN1_PRI
&& tag
== ASN1_INT
)))
981 if (!asn1_ulong_decode(ctx
, end
, &trap
->time
))
987 kfree((unsigned long *)trap
->ip_address
);
995 /*****************************************************************************
999 *****************************************************************************/
1001 static void hex_dump(const unsigned char *buf
, size_t len
)
1005 for (i
= 0; i
< len
; i
++) {
1008 printk("%02x ", *(buf
+ i
));
1014 * Parse and mangle SNMP message according to mapping.
1015 * (And this is the fucking 'basic' method).
1017 static int snmp_parse_mangle(unsigned char *msg
,
1019 const struct oct1_map
*map
,
1022 unsigned char *eoc
, *end
;
1023 unsigned int cls
, con
, tag
, vers
, pdutype
;
1024 struct asn1_ctx ctx
;
1025 struct asn1_octstr comm
;
1026 struct snmp_object
*obj
;
1031 asn1_open(&ctx
, msg
, len
);
1034 * Start of SNMP message.
1036 if (!asn1_header_decode(&ctx
, &eoc
, &cls
, &con
, &tag
))
1038 if (cls
!= ASN1_UNI
|| con
!= ASN1_CON
|| tag
!= ASN1_SEQ
)
1042 * Version 1 or 2 handled.
1044 if (!asn1_header_decode(&ctx
, &end
, &cls
, &con
, &tag
))
1046 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
1048 if (!asn1_uint_decode (&ctx
, end
, &vers
))
1051 pr_debug("bsalg: snmp version: %u\n", vers
+ 1);
1058 if (!asn1_header_decode (&ctx
, &end
, &cls
, &con
, &tag
))
1060 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_OTS
)
1062 if (!asn1_octets_decode(&ctx
, end
, &comm
.data
, &comm
.len
))
1067 pr_debug("bsalg: community: ");
1068 for (i
= 0; i
< comm
.len
; i
++)
1069 pr_cont("%c", comm
.data
[i
]);
1077 if (!asn1_header_decode(&ctx
, &eoc
, &cls
, &con
, &pdutype
))
1079 if (cls
!= ASN1_CTX
|| con
!= ASN1_CON
)
1082 static const unsigned char *const pdus
[] = {
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"
1093 if (pdutype
> SNMP_PDU_TRAP2
)
1094 pr_debug("bsalg: bad pdu type %u\n", pdutype
);
1096 pr_debug("bsalg: pdu: %s\n", pdus
[pdutype
]);
1098 if (pdutype
!= SNMP_PDU_RESPONSE
&&
1099 pdutype
!= SNMP_PDU_TRAP1
&& pdutype
!= SNMP_PDU_TRAP2
)
1103 * Request header or v1 trap
1105 if (pdutype
== SNMP_PDU_TRAP1
) {
1106 struct snmp_v1_trap trap
;
1107 unsigned char ret
= snmp_trap_decode(&ctx
, &trap
, map
, check
);
1111 kfree((unsigned long *)trap
.ip_address
);
1116 struct snmp_request req
;
1118 if (!snmp_request_decode(&ctx
, &req
))
1122 pr_debug("bsalg: request: id=0x%lx error_status=%u "
1123 "error_index=%u\n", req
.id
, req
.error_status
,
1128 * Loop through objects, look for IP addresses to mangle.
1130 if (!asn1_header_decode(&ctx
, &eoc
, &cls
, &con
, &tag
))
1133 if (cls
!= ASN1_UNI
|| con
!= ASN1_CON
|| tag
!= ASN1_SEQ
)
1136 while (!asn1_eoc_decode(&ctx
, eoc
)) {
1139 if (!snmp_object_decode(&ctx
, &obj
)) {
1148 pr_debug("bsalg: object: ");
1149 for (i
= 0; i
< obj
->id_len
; i
++) {
1152 pr_cont("%lu", obj
->id
[i
]);
1154 pr_cont(": type=%u\n", obj
->type
);
1158 if (obj
->type
== SNMP_IPADDR
)
1159 mangle_address(ctx
.begin
, ctx
.pointer
- 4, map
, check
);
1165 if (!asn1_eoc_decode(&ctx
, eoc
))
1171 /*****************************************************************************
1175 *****************************************************************************/
1178 * SNMP translation routine.
1180 static int snmp_translate(struct nf_conn
*ct
,
1181 enum ip_conntrack_info ctinfo
,
1182 struct sk_buff
*skb
)
1184 struct iphdr
*iph
= ip_hdr(skb
);
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
;
1192 * Determine mappping for application layer addresses based
1193 * on NAT manipulations for the packet.
1195 if (dir
== IP_CT_DIR_ORIGINAL
) {
1197 map
.from
= NOCT1(&ct
->tuplehash
[dir
].tuple
.src
.u3
.ip
);
1198 map
.to
= NOCT1(&ct
->tuplehash
[!dir
].tuple
.dst
.u3
.ip
);
1201 map
.from
= NOCT1(&ct
->tuplehash
[!dir
].tuple
.src
.u3
.ip
);
1202 map
.to
= NOCT1(&ct
->tuplehash
[dir
].tuple
.dst
.u3
.ip
);
1205 if (map
.from
== map
.to
)
1208 if (!snmp_parse_mangle((unsigned char *)udph
+ sizeof(struct udphdr
),
1209 paylen
, &map
, &udph
->check
)) {
1210 net_warn_ratelimited("bsalg: parser failed\n");
1216 /* We don't actually set up expectations, just adjust internal IP
1217 * addresses if this is being NATted */
1218 static int help(struct sk_buff
*skb
, unsigned int protoff
,
1220 enum ip_conntrack_info ctinfo
)
1222 int dir
= CTINFO2DIR(ctinfo
);
1224 const struct iphdr
*iph
= ip_hdr(skb
);
1225 const struct udphdr
*udph
= (struct udphdr
*)((__be32
*)iph
+ iph
->ihl
);
1227 /* SNMP replies and originating SNMP traps get mangled */
1228 if (udph
->source
== htons(SNMP_PORT
) && dir
!= IP_CT_DIR_REPLY
)
1230 if (udph
->dest
== htons(SNMP_TRAP_PORT
) && dir
!= IP_CT_DIR_ORIGINAL
)
1234 if (!(ct
->status
& IPS_NAT_MASK
))
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.
1243 if (ntohs(udph
->len
) != skb
->len
- (iph
->ihl
<< 2)) {
1244 net_warn_ratelimited("SNMP: dropping malformed packet src=%pI4 dst=%pI4\n",
1245 &iph
->saddr
, &iph
->daddr
);
1249 if (!skb_make_writable(skb
, skb
->len
))
1252 spin_lock_bh(&snmp_lock
);
1253 ret
= snmp_translate(ct
, ctinfo
, skb
);
1254 spin_unlock_bh(&snmp_lock
);
1258 static const struct nf_conntrack_expect_policy snmp_exp_policy
= {
1263 static struct nf_conntrack_helper snmp_helper __read_mostly
= {
1266 .expect_policy
= &snmp_exp_policy
,
1268 .tuple
.src
.l3num
= AF_INET
,
1269 .tuple
.src
.u
.udp
.port
= cpu_to_be16(SNMP_PORT
),
1270 .tuple
.dst
.protonum
= IPPROTO_UDP
,
1273 static struct nf_conntrack_helper snmp_trap_helper __read_mostly
= {
1276 .expect_policy
= &snmp_exp_policy
,
1277 .name
= "snmp_trap",
1278 .tuple
.src
.l3num
= AF_INET
,
1279 .tuple
.src
.u
.udp
.port
= cpu_to_be16(SNMP_TRAP_PORT
),
1280 .tuple
.dst
.protonum
= IPPROTO_UDP
,
1283 /*****************************************************************************
1287 *****************************************************************************/
1289 static int __init
nf_nat_snmp_basic_init(void)
1293 BUG_ON(nf_nat_snmp_hook
!= NULL
);
1294 RCU_INIT_POINTER(nf_nat_snmp_hook
, help
);
1296 ret
= nf_conntrack_helper_register(&snmp_trap_helper
);
1298 nf_conntrack_helper_unregister(&snmp_helper
);
1304 static void __exit
nf_nat_snmp_basic_fini(void)
1306 RCU_INIT_POINTER(nf_nat_snmp_hook
, NULL
);
1307 nf_conntrack_helper_unregister(&snmp_trap_helper
);
1310 module_init(nf_nat_snmp_basic_init
);
1311 module_exit(nf_nat_snmp_basic_fini
);
1313 module_param(debug
, int, 0600);