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, write to the Free Software
38 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
40 * Author: James Morris <jmorris@intercode.com.au>
43 * 2000-08-06: Convert to new helper API (Harald Welte).
46 #include <linux/config.h>
48 #include <linux/module.h>
49 #include <linux/types.h>
50 #include <linux/kernel.h>
51 #include <linux/moduleparam.h>
52 #include <linux/netfilter_ipv4.h>
53 #include <linux/netfilter_ipv4/ip_nat.h>
54 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
55 #include <linux/netfilter_ipv4/ip_nat_helper.h>
57 #include <linux/udp.h>
58 #include <net/checksum.h>
60 #include <asm/uaccess.h>
62 MODULE_LICENSE("GPL");
63 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
64 MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway");
67 #define SNMP_TRAP_PORT 162
68 #define NOCT1(n) (u_int8_t )((n) & 0xff)
71 static DEFINE_SPINLOCK(snmp_lock
);
74 * Application layer address mapping mimics the NAT mapping, but
75 * only for the first octet in this case (a more flexible system
76 * can be implemented if needed).
85 /*****************************************************************************
87 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
89 *****************************************************************************/
92 #define ASN1_UNI 0 /* Universal */
93 #define ASN1_APL 1 /* Application */
94 #define ASN1_CTX 2 /* Context */
95 #define ASN1_PRV 3 /* Private */
98 #define ASN1_EOC 0 /* End Of Contents */
99 #define ASN1_BOL 1 /* Boolean */
100 #define ASN1_INT 2 /* Integer */
101 #define ASN1_BTS 3 /* Bit String */
102 #define ASN1_OTS 4 /* Octet String */
103 #define ASN1_NUL 5 /* Null */
104 #define ASN1_OJI 6 /* Object Identifier */
105 #define ASN1_OJD 7 /* Object Description */
106 #define ASN1_EXT 8 /* External */
107 #define ASN1_SEQ 16 /* Sequence */
108 #define ASN1_SET 17 /* Set */
109 #define ASN1_NUMSTR 18 /* Numerical String */
110 #define ASN1_PRNSTR 19 /* Printable String */
111 #define ASN1_TEXSTR 20 /* Teletext String */
112 #define ASN1_VIDSTR 21 /* Video String */
113 #define ASN1_IA5STR 22 /* IA5 String */
114 #define ASN1_UNITIM 23 /* Universal Time */
115 #define ASN1_GENTIM 24 /* General Time */
116 #define ASN1_GRASTR 25 /* Graphical String */
117 #define ASN1_VISSTR 26 /* Visible String */
118 #define ASN1_GENSTR 27 /* General String */
120 /* Primitive / Constructed methods*/
121 #define ASN1_PRI 0 /* Primitive */
122 #define ASN1_CON 1 /* Constructed */
127 #define ASN1_ERR_NOERROR 0
128 #define ASN1_ERR_DEC_EMPTY 2
129 #define ASN1_ERR_DEC_EOC_MISMATCH 3
130 #define ASN1_ERR_DEC_LENGTH_MISMATCH 4
131 #define ASN1_ERR_DEC_BADVALUE 5
138 int error
; /* Error condition */
139 unsigned char *pointer
; /* Octet just to be decoded */
140 unsigned char *begin
; /* First octet */
141 unsigned char *end
; /* Octet after last octet */
145 * Octet string (not null terminated)
153 static void asn1_open(struct asn1_ctx
*ctx
,
158 ctx
->end
= buf
+ len
;
160 ctx
->error
= ASN1_ERR_NOERROR
;
163 static unsigned char asn1_octet_decode(struct asn1_ctx
*ctx
, unsigned char *ch
)
165 if (ctx
->pointer
>= ctx
->end
) {
166 ctx
->error
= ASN1_ERR_DEC_EMPTY
;
169 *ch
= *(ctx
->pointer
)++;
173 static unsigned char asn1_tag_decode(struct asn1_ctx
*ctx
, unsigned int *tag
)
181 if (!asn1_octet_decode(ctx
, &ch
))
185 } while ((ch
& 0x80) == 0x80);
189 static unsigned char asn1_id_decode(struct asn1_ctx
*ctx
,
196 if (!asn1_octet_decode(ctx
, &ch
))
199 *cls
= (ch
& 0xC0) >> 6;
200 *con
= (ch
& 0x20) >> 5;
204 if (!asn1_tag_decode(ctx
, tag
))
210 static unsigned char asn1_length_decode(struct asn1_ctx
*ctx
,
214 unsigned char ch
, cnt
;
216 if (!asn1_octet_decode(ctx
, &ch
))
227 cnt
= (unsigned char) (ch
& 0x7F);
231 if (!asn1_octet_decode(ctx
, &ch
))
242 static unsigned char asn1_header_decode(struct asn1_ctx
*ctx
,
248 unsigned int def
, len
;
250 if (!asn1_id_decode(ctx
, cls
, con
, tag
))
253 if (!asn1_length_decode(ctx
, &def
, &len
))
257 *eoc
= ctx
->pointer
+ len
;
263 static unsigned char asn1_eoc_decode(struct asn1_ctx
*ctx
, unsigned char *eoc
)
268 if (!asn1_octet_decode(ctx
, &ch
))
272 ctx
->error
= ASN1_ERR_DEC_EOC_MISMATCH
;
276 if (!asn1_octet_decode(ctx
, &ch
))
280 ctx
->error
= ASN1_ERR_DEC_EOC_MISMATCH
;
285 if (ctx
->pointer
!= eoc
) {
286 ctx
->error
= ASN1_ERR_DEC_LENGTH_MISMATCH
;
293 static unsigned char asn1_null_decode(struct asn1_ctx
*ctx
, unsigned char *eoc
)
299 static unsigned char asn1_long_decode(struct asn1_ctx
*ctx
,
306 if (!asn1_octet_decode(ctx
, &ch
))
309 *integer
= (signed char) ch
;
312 while (ctx
->pointer
< eoc
) {
313 if (++len
> sizeof (long)) {
314 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
318 if (!asn1_octet_decode(ctx
, &ch
))
327 static unsigned char asn1_uint_decode(struct asn1_ctx
*ctx
,
329 unsigned int *integer
)
334 if (!asn1_octet_decode(ctx
, &ch
))
338 if (ch
== 0) len
= 0;
341 while (ctx
->pointer
< eoc
) {
342 if (++len
> sizeof (unsigned int)) {
343 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
347 if (!asn1_octet_decode(ctx
, &ch
))
356 static unsigned char asn1_ulong_decode(struct asn1_ctx
*ctx
,
358 unsigned long *integer
)
363 if (!asn1_octet_decode(ctx
, &ch
))
367 if (ch
== 0) len
= 0;
370 while (ctx
->pointer
< eoc
) {
371 if (++len
> sizeof (unsigned long)) {
372 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
376 if (!asn1_octet_decode(ctx
, &ch
))
385 static unsigned char asn1_octets_decode(struct asn1_ctx
*ctx
,
387 unsigned char **octets
,
394 *octets
= kmalloc(eoc
- ctx
->pointer
, GFP_ATOMIC
);
395 if (*octets
== NULL
) {
397 printk("OOM in bsalg (%d)\n", __LINE__
);
402 while (ctx
->pointer
< eoc
) {
403 if (!asn1_octet_decode(ctx
, (unsigned char *)ptr
++)) {
413 static unsigned char asn1_subid_decode(struct asn1_ctx
*ctx
,
414 unsigned long *subid
)
421 if (!asn1_octet_decode(ctx
, &ch
))
426 } while ((ch
& 0x80) == 0x80);
430 static unsigned char asn1_oid_decode(struct asn1_ctx
*ctx
,
439 size
= eoc
- ctx
->pointer
+ 1;
440 *oid
= kmalloc(size
* sizeof(unsigned long), GFP_ATOMIC
);
443 printk("OOM in bsalg (%d)\n", __LINE__
);
449 if (!asn1_subid_decode(ctx
, &subid
)) {
458 } else if (subid
< 80) {
460 optr
[1] = subid
- 40;
463 optr
[1] = subid
- 80;
469 while (ctx
->pointer
< eoc
) {
470 if (++(*len
) > size
) {
471 ctx
->error
= ASN1_ERR_DEC_BADVALUE
;
477 if (!asn1_subid_decode(ctx
, optr
++)) {
486 /*****************************************************************************
488 * SNMP decoding routines (gxsnmp author Dirk Wisse)
490 *****************************************************************************/
499 #define SNMP_SIZE_COMM 256
500 #define SNMP_SIZE_OBJECTID 128
501 #define SNMP_SIZE_BUFCHR 256
502 #define SNMP_SIZE_BUFINT 128
503 #define SNMP_SIZE_SMALLOBJECTID 16
506 #define SNMP_PDU_GET 0
507 #define SNMP_PDU_NEXT 1
508 #define SNMP_PDU_RESPONSE 2
509 #define SNMP_PDU_SET 3
510 #define SNMP_PDU_TRAP1 4
511 #define SNMP_PDU_BULK 5
512 #define SNMP_PDU_INFORM 6
513 #define SNMP_PDU_TRAP2 7
516 #define SNMP_NOERROR 0
517 #define SNMP_TOOBIG 1
518 #define SNMP_NOSUCHNAME 2
519 #define SNMP_BADVALUE 3
520 #define SNMP_READONLY 4
521 #define SNMP_GENERROR 5
522 #define SNMP_NOACCESS 6
523 #define SNMP_WRONGTYPE 7
524 #define SNMP_WRONGLENGTH 8
525 #define SNMP_WRONGENCODING 9
526 #define SNMP_WRONGVALUE 10
527 #define SNMP_NOCREATION 11
528 #define SNMP_INCONSISTENTVALUE 12
529 #define SNMP_RESOURCEUNAVAILABLE 13
530 #define SNMP_COMMITFAILED 14
531 #define SNMP_UNDOFAILED 15
532 #define SNMP_AUTHORIZATIONERROR 16
533 #define SNMP_NOTWRITABLE 17
534 #define SNMP_INCONSISTENTNAME 18
536 /* General SNMP V1 Traps */
537 #define SNMP_TRAP_COLDSTART 0
538 #define SNMP_TRAP_WARMSTART 1
539 #define SNMP_TRAP_LINKDOWN 2
540 #define SNMP_TRAP_LINKUP 3
541 #define SNMP_TRAP_AUTFAILURE 4
542 #define SNMP_TRAP_EQPNEIGHBORLOSS 5
543 #define SNMP_TRAP_ENTSPECIFIC 6
547 #define SNMP_INTEGER 1 /* l */
548 #define SNMP_OCTETSTR 2 /* c */
549 #define SNMP_DISPLAYSTR 2 /* c */
550 #define SNMP_OBJECTID 3 /* ul */
551 #define SNMP_IPADDR 4 /* uc */
552 #define SNMP_COUNTER 5 /* ul */
553 #define SNMP_GAUGE 6 /* ul */
554 #define SNMP_TIMETICKS 7 /* ul */
555 #define SNMP_OPAQUE 8 /* c */
557 /* Additional SNMPv2 Types */
558 #define SNMP_UINTEGER 5 /* ul */
559 #define SNMP_BITSTR 9 /* uc */
560 #define SNMP_NSAP 10 /* uc */
561 #define SNMP_COUNTER64 11 /* ul */
562 #define SNMP_NOSUCHOBJECT 12
563 #define SNMP_NOSUCHINSTANCE 13
564 #define SNMP_ENDOFMIBVIEW 14
568 unsigned char uc
[0]; /* 8 bit unsigned */
569 char c
[0]; /* 8 bit signed */
570 unsigned long ul
[0]; /* 32 bit unsigned */
571 long l
[0]; /* 32 bit signed */
579 unsigned int syntax_len
;
580 union snmp_syntax syntax
;
586 unsigned int error_status
;
587 unsigned int error_index
;
594 unsigned long ip_address
; /* pointer */
595 unsigned int general
;
596 unsigned int specific
;
613 static inline void mangle_address(unsigned char *begin
,
615 const struct oct1_map
*map
,
624 static struct snmp_cnv snmp_conv
[] =
626 {ASN1_UNI
, ASN1_NUL
, SNMP_NULL
},
627 {ASN1_UNI
, ASN1_INT
, SNMP_INTEGER
},
628 {ASN1_UNI
, ASN1_OTS
, SNMP_OCTETSTR
},
629 {ASN1_UNI
, ASN1_OTS
, SNMP_DISPLAYSTR
},
630 {ASN1_UNI
, ASN1_OJI
, SNMP_OBJECTID
},
631 {ASN1_APL
, SNMP_IPA
, SNMP_IPADDR
},
632 {ASN1_APL
, SNMP_CNT
, SNMP_COUNTER
}, /* Counter32 */
633 {ASN1_APL
, SNMP_GGE
, SNMP_GAUGE
}, /* Gauge32 == Unsigned32 */
634 {ASN1_APL
, SNMP_TIT
, SNMP_TIMETICKS
},
635 {ASN1_APL
, SNMP_OPQ
, SNMP_OPAQUE
},
637 /* SNMPv2 data types and errors */
638 {ASN1_UNI
, ASN1_BTS
, SNMP_BITSTR
},
639 {ASN1_APL
, SNMP_C64
, SNMP_COUNTER64
},
640 {ASN1_CTX
, SERR_NSO
, SNMP_NOSUCHOBJECT
},
641 {ASN1_CTX
, SERR_NSI
, SNMP_NOSUCHINSTANCE
},
642 {ASN1_CTX
, SERR_EOM
, SNMP_ENDOFMIBVIEW
},
646 static unsigned char snmp_tag_cls2syntax(unsigned int tag
,
648 unsigned short *syntax
)
650 struct snmp_cnv
*cnv
;
654 while (cnv
->syntax
!= -1) {
655 if (cnv
->tag
== tag
&& cnv
->class == cls
) {
656 *syntax
= cnv
->syntax
;
664 static unsigned char snmp_object_decode(struct asn1_ctx
*ctx
,
665 struct snmp_object
**obj
)
667 unsigned int cls
, con
, tag
, len
, idlen
;
669 unsigned char *eoc
, *end
, *p
;
670 unsigned long *lp
, *id
;
677 if (!asn1_header_decode(ctx
, &eoc
, &cls
, &con
, &tag
))
680 if (cls
!= ASN1_UNI
|| con
!= ASN1_CON
|| tag
!= ASN1_SEQ
)
683 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
686 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_OJI
)
689 if (!asn1_oid_decode(ctx
, end
, &id
, &idlen
))
692 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
)) {
697 if (con
!= ASN1_PRI
) {
702 if (!snmp_tag_cls2syntax(tag
, cls
, &type
)) {
710 if (!asn1_long_decode(ctx
, end
, &l
)) {
714 *obj
= kmalloc(sizeof(struct snmp_object
) + len
,
719 printk("OOM in bsalg (%d)\n", __LINE__
);
722 (*obj
)->syntax
.l
[0] = l
;
726 if (!asn1_octets_decode(ctx
, end
, &p
, &len
)) {
730 *obj
= kmalloc(sizeof(struct snmp_object
) + len
,
735 printk("OOM in bsalg (%d)\n", __LINE__
);
738 memcpy((*obj
)->syntax
.c
, p
, len
);
742 case SNMP_NOSUCHOBJECT
:
743 case SNMP_NOSUCHINSTANCE
:
744 case SNMP_ENDOFMIBVIEW
:
746 *obj
= kmalloc(sizeof(struct snmp_object
), GFP_ATOMIC
);
750 printk("OOM in bsalg (%d)\n", __LINE__
);
753 if (!asn1_null_decode(ctx
, end
)) {
761 if (!asn1_oid_decode(ctx
, end
, (unsigned long **)&lp
, &len
)) {
765 len
*= sizeof(unsigned long);
766 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
770 printk("OOM in bsalg (%d)\n", __LINE__
);
773 memcpy((*obj
)->syntax
.ul
, lp
, len
);
777 if (!asn1_octets_decode(ctx
, end
, &p
, &len
)) {
786 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
791 printk("OOM in bsalg (%d)\n", __LINE__
);
794 memcpy((*obj
)->syntax
.uc
, p
, len
);
800 len
= sizeof(unsigned long);
801 if (!asn1_ulong_decode(ctx
, end
, &ul
)) {
805 *obj
= kmalloc(sizeof(struct snmp_object
) + len
, GFP_ATOMIC
);
809 printk("OOM in bsalg (%d)\n", __LINE__
);
812 (*obj
)->syntax
.ul
[0] = ul
;
819 (*obj
)->syntax_len
= len
;
822 (*obj
)->id_len
= idlen
;
824 if (!asn1_eoc_decode(ctx
, eoc
)) {
833 static unsigned char snmp_request_decode(struct asn1_ctx
*ctx
,
834 struct snmp_request
*request
)
836 unsigned int cls
, con
, tag
;
839 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
842 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
845 if (!asn1_ulong_decode(ctx
, end
, &request
->id
))
848 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
851 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
854 if (!asn1_uint_decode(ctx
, end
, &request
->error_status
))
857 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
860 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
863 if (!asn1_uint_decode(ctx
, end
, &request
->error_index
))
870 * Fast checksum update for possibly oddly-aligned UDP byte, from the
871 * code example in the draft.
873 static void fast_csum(unsigned char *csum
,
874 const unsigned char *optr
,
875 const unsigned char *nptr
,
880 x
= csum
[0] * 256 + csum
[1];
884 if (odd
) old
= optr
[0] * 256;
893 if (odd
) new = nptr
[0] * 256;
909 * - begin points to the start of the snmp messgae
910 * - addr points to the start of the address
912 static inline void mangle_address(unsigned char *begin
,
914 const struct oct1_map
*map
,
917 if (map
->from
== NOCT1(*addr
)) {
921 memcpy(&old
, (unsigned char *)addr
, sizeof(old
));
925 /* Update UDP checksum if being used */
927 unsigned char odd
= !((addr
- begin
) % 2);
929 fast_csum((unsigned char *)check
,
930 &map
->from
, &map
->to
, odd
);
935 printk(KERN_DEBUG
"bsalg: mapped %u.%u.%u.%u to "
936 "%u.%u.%u.%u\n", NIPQUAD(old
), NIPQUAD(*addr
));
940 static unsigned char snmp_trap_decode(struct asn1_ctx
*ctx
,
941 struct snmp_v1_trap
*trap
,
942 const struct oct1_map
*map
,
945 unsigned int cls
, con
, tag
, len
;
948 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
951 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_OJI
)
954 if (!asn1_oid_decode(ctx
, end
, &trap
->id
, &trap
->id_len
))
957 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
960 if (!((cls
== ASN1_APL
&& con
== ASN1_PRI
&& tag
== SNMP_IPA
) ||
961 (cls
== ASN1_UNI
&& con
== ASN1_PRI
&& tag
== ASN1_OTS
)))
964 if (!asn1_octets_decode(ctx
, end
, (unsigned char **)&trap
->ip_address
, &len
))
971 mangle_address(ctx
->begin
, ctx
->pointer
- 4, map
, check
);
973 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
976 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
979 if (!asn1_uint_decode(ctx
, end
, &trap
->general
))
982 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
985 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
988 if (!asn1_uint_decode(ctx
, end
, &trap
->specific
))
991 if (!asn1_header_decode(ctx
, &end
, &cls
, &con
, &tag
))
994 if (!((cls
== ASN1_APL
&& con
== ASN1_PRI
&& tag
== SNMP_TIT
) ||
995 (cls
== ASN1_UNI
&& con
== ASN1_PRI
&& tag
== ASN1_INT
)))
998 if (!asn1_ulong_decode(ctx
, end
, &trap
->time
))
1007 kfree((unsigned long *)trap
->ip_address
);
1012 /*****************************************************************************
1016 *****************************************************************************/
1018 static void hex_dump(unsigned char *buf
, size_t len
)
1022 for (i
= 0; i
< len
; i
++) {
1025 printk("%02x ", *(buf
+ i
));
1031 * Parse and mangle SNMP message according to mapping.
1032 * (And this is the fucking 'basic' method).
1034 static int snmp_parse_mangle(unsigned char *msg
,
1036 const struct oct1_map
*map
,
1039 unsigned char *eoc
, *end
;
1040 unsigned int cls
, con
, tag
, vers
, pdutype
;
1041 struct asn1_ctx ctx
;
1042 struct asn1_octstr comm
;
1043 struct snmp_object
**obj
;
1048 asn1_open(&ctx
, msg
, len
);
1051 * Start of SNMP message.
1053 if (!asn1_header_decode(&ctx
, &eoc
, &cls
, &con
, &tag
))
1055 if (cls
!= ASN1_UNI
|| con
!= ASN1_CON
|| tag
!= ASN1_SEQ
)
1059 * Version 1 or 2 handled.
1061 if (!asn1_header_decode(&ctx
, &end
, &cls
, &con
, &tag
))
1063 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_INT
)
1065 if (!asn1_uint_decode (&ctx
, end
, &vers
))
1068 printk(KERN_DEBUG
"bsalg: snmp version: %u\n", vers
+ 1);
1075 if (!asn1_header_decode (&ctx
, &end
, &cls
, &con
, &tag
))
1077 if (cls
!= ASN1_UNI
|| con
!= ASN1_PRI
|| tag
!= ASN1_OTS
)
1079 if (!asn1_octets_decode(&ctx
, end
, &comm
.data
, &comm
.len
))
1084 printk(KERN_DEBUG
"bsalg: community: ");
1085 for (i
= 0; i
< comm
.len
; i
++)
1086 printk("%c", comm
.data
[i
]);
1094 if (!asn1_header_decode(&ctx
, &eoc
, &cls
, &con
, &pdutype
))
1096 if (cls
!= ASN1_CTX
|| con
!= ASN1_CON
)
1099 unsigned char *pdus
[] = {
1100 [SNMP_PDU_GET
] = "get",
1101 [SNMP_PDU_NEXT
] = "get-next",
1102 [SNMP_PDU_RESPONSE
] = "response",
1103 [SNMP_PDU_SET
] = "set",
1104 [SNMP_PDU_TRAP1
] = "trapv1",
1105 [SNMP_PDU_BULK
] = "bulk",
1106 [SNMP_PDU_INFORM
] = "inform",
1107 [SNMP_PDU_TRAP2
] = "trapv2"
1110 if (pdutype
> SNMP_PDU_TRAP2
)
1111 printk(KERN_DEBUG
"bsalg: bad pdu type %u\n", pdutype
);
1113 printk(KERN_DEBUG
"bsalg: pdu: %s\n", pdus
[pdutype
]);
1115 if (pdutype
!= SNMP_PDU_RESPONSE
&&
1116 pdutype
!= SNMP_PDU_TRAP1
&& pdutype
!= SNMP_PDU_TRAP2
)
1120 * Request header or v1 trap
1122 if (pdutype
== SNMP_PDU_TRAP1
) {
1123 struct snmp_v1_trap trap
;
1124 unsigned char ret
= snmp_trap_decode(&ctx
, &trap
, map
, check
);
1126 /* Discard trap allocations regardless */
1128 kfree((unsigned long *)trap
.ip_address
);
1134 struct snmp_request req
;
1136 if (!snmp_request_decode(&ctx
, &req
))
1140 printk(KERN_DEBUG
"bsalg: request: id=0x%lx error_status=%u "
1141 "error_index=%u\n", req
.id
, req
.error_status
,
1146 * Loop through objects, look for IP addresses to mangle.
1148 if (!asn1_header_decode(&ctx
, &eoc
, &cls
, &con
, &tag
))
1151 if (cls
!= ASN1_UNI
|| con
!= ASN1_CON
|| tag
!= ASN1_SEQ
)
1154 obj
= kmalloc(sizeof(struct snmp_object
), GFP_ATOMIC
);
1156 if (net_ratelimit())
1157 printk(KERN_WARNING
"OOM in bsalg(%d)\n", __LINE__
);
1161 while (!asn1_eoc_decode(&ctx
, eoc
)) {
1164 if (!snmp_object_decode(&ctx
, obj
)) {
1174 printk(KERN_DEBUG
"bsalg: object: ");
1175 for (i
= 0; i
< (*obj
)->id_len
; i
++) {
1178 printk("%lu", (*obj
)->id
[i
]);
1180 printk(": type=%u\n", (*obj
)->type
);
1184 if ((*obj
)->type
== SNMP_IPADDR
)
1185 mangle_address(ctx
.begin
, ctx
.pointer
- 4 , map
, check
);
1192 if (!asn1_eoc_decode(&ctx
, eoc
))
1198 /*****************************************************************************
1202 *****************************************************************************/
1205 * SNMP translation routine.
1207 static int snmp_translate(struct ip_conntrack
*ct
,
1208 enum ip_conntrack_info ctinfo
,
1209 struct sk_buff
**pskb
)
1211 struct iphdr
*iph
= (*pskb
)->nh
.iph
;
1212 struct udphdr
*udph
= (struct udphdr
*)((u_int32_t
*)iph
+ iph
->ihl
);
1213 u_int16_t udplen
= ntohs(udph
->len
);
1214 u_int16_t paylen
= udplen
- sizeof(struct udphdr
);
1215 int dir
= CTINFO2DIR(ctinfo
);
1216 struct oct1_map map
;
1219 * Determine mappping for application layer addresses based
1220 * on NAT manipulations for the packet.
1222 if (dir
== IP_CT_DIR_ORIGINAL
) {
1224 map
.from
= NOCT1(ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
.src
.ip
);
1225 map
.to
= NOCT1(ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.ip
);
1228 map
.from
= NOCT1(ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.ip
);
1229 map
.to
= NOCT1(ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
.dst
.ip
);
1232 if (map
.from
== map
.to
)
1235 if (!snmp_parse_mangle((unsigned char *)udph
+ sizeof(struct udphdr
),
1236 paylen
, &map
, &udph
->check
)) {
1237 if (net_ratelimit())
1238 printk(KERN_WARNING
"bsalg: parser failed\n");
1244 /* We don't actually set up expectations, just adjust internal IP
1245 * addresses if this is being NATted */
1246 static int help(struct sk_buff
**pskb
,
1247 struct ip_conntrack
*ct
,
1248 enum ip_conntrack_info ctinfo
)
1250 int dir
= CTINFO2DIR(ctinfo
);
1252 struct iphdr
*iph
= (*pskb
)->nh
.iph
;
1253 struct udphdr
*udph
= (struct udphdr
*)((u_int32_t
*)iph
+ iph
->ihl
);
1255 /* SNMP replies and originating SNMP traps get mangled */
1256 if (udph
->source
== ntohs(SNMP_PORT
) && dir
!= IP_CT_DIR_REPLY
)
1258 if (udph
->dest
== ntohs(SNMP_TRAP_PORT
) && dir
!= IP_CT_DIR_ORIGINAL
)
1262 if (!(ct
->status
& IPS_NAT_MASK
))
1266 * Make sure the packet length is ok. So far, we were only guaranteed
1267 * to have a valid length IP header plus 8 bytes, which means we have
1268 * enough room for a UDP header. Just verify the UDP length field so we
1269 * can mess around with the payload.
1271 if (ntohs(udph
->len
) != (*pskb
)->len
- (iph
->ihl
<< 2)) {
1272 if (net_ratelimit())
1273 printk(KERN_WARNING
"SNMP: dropping malformed packet "
1274 "src=%u.%u.%u.%u dst=%u.%u.%u.%u\n",
1275 NIPQUAD(iph
->saddr
), NIPQUAD(iph
->daddr
));
1279 if (!skb_make_writable(pskb
, (*pskb
)->len
))
1282 spin_lock_bh(&snmp_lock
);
1283 ret
= snmp_translate(ct
, ctinfo
, pskb
);
1284 spin_unlock_bh(&snmp_lock
);
1288 static struct ip_conntrack_helper snmp_helper
= {
1295 .tuple
= { .src
= { .u
= { __constant_htons(SNMP_PORT
) } },
1296 .dst
= { .protonum
= IPPROTO_UDP
},
1298 .mask
= { .src
= { .u
= { 0xFFFF } },
1299 .dst
= { .protonum
= 0xFF },
1303 static struct ip_conntrack_helper snmp_trap_helper
= {
1308 .name
= "snmp_trap",
1310 .tuple
= { .src
= { .u
= { __constant_htons(SNMP_TRAP_PORT
) } },
1311 .dst
= { .protonum
= IPPROTO_UDP
},
1313 .mask
= { .src
= { .u
= { 0xFFFF } },
1314 .dst
= { .protonum
= 0xFF },
1318 /*****************************************************************************
1322 *****************************************************************************/
1324 static int __init
init(void)
1328 ret
= ip_conntrack_helper_register(&snmp_helper
);
1331 ret
= ip_conntrack_helper_register(&snmp_trap_helper
);
1333 ip_conntrack_helper_unregister(&snmp_helper
);
1339 static void __exit
fini(void)
1341 ip_conntrack_helper_unregister(&snmp_helper
);
1342 ip_conntrack_helper_unregister(&snmp_trap_helper
);
1348 module_param(debug
, bool, 0600);