+++ /dev/null
-/*
- * nf_nat_snmp_basic.c
- *
- * Basic SNMP Application Layer Gateway
- *
- * This IP NAT module is intended for use with SNMP network
- * discovery and monitoring applications where target networks use
- * conflicting private address realms.
- *
- * Static NAT is used to remap the networks from the view of the network
- * management system at the IP layer, and this module remaps some application
- * layer addresses to match.
- *
- * The simplest form of ALG is performed, where only tagged IP addresses
- * are modified. The module does not need to be MIB aware and only scans
- * messages at the ASN.1/BER level.
- *
- * Currently, only SNMPv1 and SNMPv2 are supported.
- *
- * More information on ALG and associated issues can be found in
- * RFC 2962
- *
- * The ASB.1/BER parsing code is derived from the gxsnmp package by Gregory
- * McLean & Jochen Friedrich, stripped down for use in the kernel.
- *
- * Copyright (c) 2000 RP Internet (www.rpi.net.au).
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
- *
- * Author: James Morris <jmorris@intercode.com.au>
- *
- * Copyright (c) 2006-2010 Patrick McHardy <kaber@trash.net>
- */
-#include <linux/module.h>
-#include <linux/moduleparam.h>
-#include <linux/types.h>
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/in.h>
-#include <linux/ip.h>
-#include <linux/udp.h>
-#include <net/checksum.h>
-#include <net/udp.h>
-
-#include <net/netfilter/nf_nat.h>
-#include <net/netfilter/nf_conntrack_expect.h>
-#include <net/netfilter/nf_conntrack_helper.h>
-#include <net/netfilter/nf_nat_helper.h>
-#include <linux/netfilter/nf_conntrack_snmp.h>
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
-MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway");
-MODULE_ALIAS("ip_nat_snmp_basic");
-
-#define SNMP_PORT 161
-#define SNMP_TRAP_PORT 162
-#define NOCT1(n) (*(u8 *)(n))
-
-static DEFINE_SPINLOCK(snmp_lock);
-
-/*
- * Application layer address mapping mimics the NAT mapping, but
- * only for the first octet in this case (a more flexible system
- * can be implemented if needed).
- */
-struct oct1_map
-{
- u_int8_t from;
- u_int8_t to;
-};
-
-
-/* Class */
-#define ASN1_UNI 0 /* Universal */
-#define ASN1_APL 1 /* Application */
-#define ASN1_CTX 2 /* Context */
-#define ASN1_PRV 3 /* Private */
-
-/* Tag */
-#define ASN1_EOC 0 /* End Of Contents */
-#define ASN1_BOL 1 /* Boolean */
-#define ASN1_INT 2 /* Integer */
-#define ASN1_BTS 3 /* Bit String */
-#define ASN1_OTS 4 /* Octet String */
-#define ASN1_NUL 5 /* Null */
-#define ASN1_OJI 6 /* Object Identifier */
-#define ASN1_OJD 7 /* Object Description */
-#define ASN1_EXT 8 /* External */
-#define ASN1_SEQ 16 /* Sequence */
-#define ASN1_SET 17 /* Set */
-#define ASN1_NUMSTR 18 /* Numerical String */
-#define ASN1_PRNSTR 19 /* Printable String */
-#define ASN1_TEXSTR 20 /* Teletext String */
-#define ASN1_VIDSTR 21 /* Video String */
-#define ASN1_IA5STR 22 /* IA5 String */
-#define ASN1_UNITIM 23 /* Universal Time */
-#define ASN1_GENTIM 24 /* General Time */
-#define ASN1_GRASTR 25 /* Graphical String */
-#define ASN1_VISSTR 26 /* Visible String */
-#define ASN1_GENSTR 27 /* General String */
-
-/* Primitive / Constructed methods*/
-#define ASN1_PRI 0 /* Primitive */
-#define ASN1_CON 1 /* Constructed */
-
-/*
- * Error codes.
- */
-#define ASN1_ERR_NOERROR 0
-#define ASN1_ERR_DEC_EMPTY 2
-#define ASN1_ERR_DEC_EOC_MISMATCH 3
-#define ASN1_ERR_DEC_LENGTH_MISMATCH 4
-#define ASN1_ERR_DEC_BADVALUE 5
-
-/*
- * ASN.1 context.
- */
-struct asn1_ctx
-{
- int error; /* Error condition */
- unsigned char *pointer; /* Octet just to be decoded */
- unsigned char *begin; /* First octet */
- unsigned char *end; /* Octet after last octet */
-};
-
-/*
- * Octet string (not null terminated)
- */
-struct asn1_octstr
-{
- unsigned char *data;
- unsigned int len;
-};
-
-static void asn1_open(struct asn1_ctx *ctx,
- unsigned char *buf,
- unsigned int len)
-{
- ctx->begin = buf;
- ctx->end = buf + len;
- ctx->pointer = buf;
- ctx->error = ASN1_ERR_NOERROR;
-}
-
-static unsigned char asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
-{
- if (ctx->pointer >= ctx->end) {
- ctx->error = ASN1_ERR_DEC_EMPTY;
- return 0;
- }
- *ch = *(ctx->pointer)++;
- return 1;
-}
-
-static unsigned char asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
-{
- unsigned char ch;
-
- *tag = 0;
-
- do
- {
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
- *tag <<= 7;
- *tag |= ch & 0x7F;
- } while ((ch & 0x80) == 0x80);
- return 1;
-}
-
-static unsigned char asn1_id_decode(struct asn1_ctx *ctx,
- unsigned int *cls,
- unsigned int *con,
- unsigned int *tag)
-{
- unsigned char ch;
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *cls = (ch & 0xC0) >> 6;
- *con = (ch & 0x20) >> 5;
- *tag = (ch & 0x1F);
-
- if (*tag == 0x1F) {
- if (!asn1_tag_decode(ctx, tag))
- return 0;
- }
- return 1;
-}
-
-static unsigned char asn1_length_decode(struct asn1_ctx *ctx,
- unsigned int *def,
- unsigned int *len)
-{
- unsigned char ch, cnt;
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- if (ch == 0x80)
- *def = 0;
- else {
- *def = 1;
-
- if (ch < 0x80)
- *len = ch;
- else {
- cnt = ch & 0x7F;
- *len = 0;
-
- while (cnt > 0) {
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
- *len <<= 8;
- *len |= ch;
- cnt--;
- }
- }
- }
-
- /* don't trust len bigger than ctx buffer */
- if (*len > ctx->end - ctx->pointer)
- return 0;
-
- return 1;
-}
-
-static unsigned char asn1_header_decode(struct asn1_ctx *ctx,
- unsigned char **eoc,
- unsigned int *cls,
- unsigned int *con,
- unsigned int *tag)
-{
- unsigned int def, len;
-
- if (!asn1_id_decode(ctx, cls, con, tag))
- return 0;
-
- def = len = 0;
- if (!asn1_length_decode(ctx, &def, &len))
- return 0;
-
- /* primitive shall be definite, indefinite shall be constructed */
- if (*con == ASN1_PRI && !def)
- return 0;
-
- if (def)
- *eoc = ctx->pointer + len;
- else
- *eoc = NULL;
- return 1;
-}
-
-static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
-{
- unsigned char ch;
-
- if (eoc == NULL) {
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- if (ch != 0x00) {
- ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
- return 0;
- }
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- if (ch != 0x00) {
- ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
- return 0;
- }
- return 1;
- } else {
- if (ctx->pointer != eoc) {
- ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
- return 0;
- }
- return 1;
- }
-}
-
-static unsigned char asn1_null_decode(struct asn1_ctx *ctx, unsigned char *eoc)
-{
- ctx->pointer = eoc;
- return 1;
-}
-
-static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- long *integer)
-{
- unsigned char ch;
- unsigned int len;
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *integer = (signed char) ch;
- len = 1;
-
- while (ctx->pointer < eoc) {
- if (++len > sizeof (long)) {
- ctx->error = ASN1_ERR_DEC_BADVALUE;
- return 0;
- }
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *integer <<= 8;
- *integer |= ch;
- }
- return 1;
-}
-
-static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned int *integer)
-{
- unsigned char ch;
- unsigned int len;
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *integer = ch;
- if (ch == 0) len = 0;
- else len = 1;
-
- while (ctx->pointer < eoc) {
- if (++len > sizeof (unsigned int)) {
- ctx->error = ASN1_ERR_DEC_BADVALUE;
- return 0;
- }
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *integer <<= 8;
- *integer |= ch;
- }
- return 1;
-}
-
-static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned long *integer)
-{
- unsigned char ch;
- unsigned int len;
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *integer = ch;
- if (ch == 0) len = 0;
- else len = 1;
-
- while (ctx->pointer < eoc) {
- if (++len > sizeof (unsigned long)) {
- ctx->error = ASN1_ERR_DEC_BADVALUE;
- return 0;
- }
-
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *integer <<= 8;
- *integer |= ch;
- }
- return 1;
-}
-
-static unsigned char asn1_octets_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned char **octets,
- unsigned int *len)
-{
- unsigned char *ptr;
-
- *len = 0;
-
- *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
- if (*octets == NULL)
- return 0;
-
- ptr = *octets;
- while (ctx->pointer < eoc) {
- if (!asn1_octet_decode(ctx, ptr++)) {
- kfree(*octets);
- *octets = NULL;
- return 0;
- }
- (*len)++;
- }
- return 1;
-}
-
-static unsigned char asn1_subid_decode(struct asn1_ctx *ctx,
- unsigned long *subid)
-{
- unsigned char ch;
-
- *subid = 0;
-
- do {
- if (!asn1_octet_decode(ctx, &ch))
- return 0;
-
- *subid <<= 7;
- *subid |= ch & 0x7F;
- } while ((ch & 0x80) == 0x80);
- return 1;
-}
-
-static unsigned char asn1_oid_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned long **oid,
- unsigned int *len)
-{
- unsigned long subid;
- unsigned long *optr;
- size_t size;
-
- size = eoc - ctx->pointer + 1;
-
- /* first subid actually encodes first two subids */
- if (size < 2 || size > ULONG_MAX/sizeof(unsigned long))
- return 0;
-
- *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
- if (*oid == NULL)
- return 0;
-
- optr = *oid;
-
- if (!asn1_subid_decode(ctx, &subid)) {
- kfree(*oid);
- *oid = NULL;
- return 0;
- }
-
- if (subid < 40) {
- optr[0] = 0;
- optr[1] = subid;
- } else if (subid < 80) {
- optr[0] = 1;
- optr[1] = subid - 40;
- } else {
- optr[0] = 2;
- optr[1] = subid - 80;
- }
-
- *len = 2;
- optr += 2;
-
- while (ctx->pointer < eoc) {
- if (++(*len) > size) {
- ctx->error = ASN1_ERR_DEC_BADVALUE;
- kfree(*oid);
- *oid = NULL;
- return 0;
- }
-
- if (!asn1_subid_decode(ctx, optr++)) {
- kfree(*oid);
- *oid = NULL;
- return 0;
- }
- }
- return 1;
-}
-
-/* SNMP Versions */
-#define SNMP_V1 0
-#define SNMP_V2C 1
-#define SNMP_V2 2
-#define SNMP_V3 3
-
-/* Default Sizes */
-#define SNMP_SIZE_COMM 256
-#define SNMP_SIZE_OBJECTID 128
-#define SNMP_SIZE_BUFCHR 256
-#define SNMP_SIZE_BUFINT 128
-#define SNMP_SIZE_SMALLOBJECTID 16
-
-/* Requests */
-#define SNMP_PDU_GET 0
-#define SNMP_PDU_NEXT 1
-#define SNMP_PDU_RESPONSE 2
-#define SNMP_PDU_SET 3
-#define SNMP_PDU_TRAP1 4
-#define SNMP_PDU_BULK 5
-#define SNMP_PDU_INFORM 6
-#define SNMP_PDU_TRAP2 7
-
-/* Errors */
-#define SNMP_NOERROR 0
-#define SNMP_TOOBIG 1
-#define SNMP_NOSUCHNAME 2
-#define SNMP_BADVALUE 3
-#define SNMP_READONLY 4
-#define SNMP_GENERROR 5
-#define SNMP_NOACCESS 6
-#define SNMP_WRONGTYPE 7
-#define SNMP_WRONGLENGTH 8
-#define SNMP_WRONGENCODING 9
-#define SNMP_WRONGVALUE 10
-#define SNMP_NOCREATION 11
-#define SNMP_INCONSISTENTVALUE 12
-#define SNMP_RESOURCEUNAVAILABLE 13
-#define SNMP_COMMITFAILED 14
-#define SNMP_UNDOFAILED 15
-#define SNMP_AUTHORIZATIONERROR 16
-#define SNMP_NOTWRITABLE 17
-#define SNMP_INCONSISTENTNAME 18
-
-/* General SNMP V1 Traps */
-#define SNMP_TRAP_COLDSTART 0
-#define SNMP_TRAP_WARMSTART 1
-#define SNMP_TRAP_LINKDOWN 2
-#define SNMP_TRAP_LINKUP 3
-#define SNMP_TRAP_AUTFAILURE 4
-#define SNMP_TRAP_EQPNEIGHBORLOSS 5
-#define SNMP_TRAP_ENTSPECIFIC 6
-
-/* SNMPv1 Types */
-#define SNMP_NULL 0
-#define SNMP_INTEGER 1 /* l */
-#define SNMP_OCTETSTR 2 /* c */
-#define SNMP_DISPLAYSTR 2 /* c */
-#define SNMP_OBJECTID 3 /* ul */
-#define SNMP_IPADDR 4 /* uc */
-#define SNMP_COUNTER 5 /* ul */
-#define SNMP_GAUGE 6 /* ul */
-#define SNMP_TIMETICKS 7 /* ul */
-#define SNMP_OPAQUE 8 /* c */
-
-/* Additional SNMPv2 Types */
-#define SNMP_UINTEGER 5 /* ul */
-#define SNMP_BITSTR 9 /* uc */
-#define SNMP_NSAP 10 /* uc */
-#define SNMP_COUNTER64 11 /* ul */
-#define SNMP_NOSUCHOBJECT 12
-#define SNMP_NOSUCHINSTANCE 13
-#define SNMP_ENDOFMIBVIEW 14
-
-union snmp_syntax
-{
- unsigned char uc[0]; /* 8 bit unsigned */
- char c[0]; /* 8 bit signed */
- unsigned long ul[0]; /* 32 bit unsigned */
- long l[0]; /* 32 bit signed */
-};
-
-struct snmp_object
-{
- unsigned long *id;
- unsigned int id_len;
- unsigned short type;
- unsigned int syntax_len;
- union snmp_syntax syntax;
-};
-
-struct snmp_request
-{
- unsigned long id;
- unsigned int error_status;
- unsigned int error_index;
-};
-
-struct snmp_v1_trap
-{
- unsigned long *id;
- unsigned int id_len;
- unsigned long ip_address; /* pointer */
- unsigned int general;
- unsigned int specific;
- unsigned long time;
-};
-
-/* SNMP types */
-#define SNMP_IPA 0
-#define SNMP_CNT 1
-#define SNMP_GGE 2
-#define SNMP_TIT 3
-#define SNMP_OPQ 4
-#define SNMP_C64 6
-
-/* SNMP errors */
-#define SERR_NSO 0
-#define SERR_NSI 1
-#define SERR_EOM 2
-
-static inline void mangle_address(unsigned char *begin,
- unsigned char *addr,
- const struct oct1_map *map,
- __sum16 *check);
-struct snmp_cnv
-{
- unsigned int class;
- unsigned int tag;
- int syntax;
-};
-
-static const struct snmp_cnv snmp_conv[] = {
- {ASN1_UNI, ASN1_NUL, SNMP_NULL},
- {ASN1_UNI, ASN1_INT, SNMP_INTEGER},
- {ASN1_UNI, ASN1_OTS, SNMP_OCTETSTR},
- {ASN1_UNI, ASN1_OTS, SNMP_DISPLAYSTR},
- {ASN1_UNI, ASN1_OJI, SNMP_OBJECTID},
- {ASN1_APL, SNMP_IPA, SNMP_IPADDR},
- {ASN1_APL, SNMP_CNT, SNMP_COUNTER}, /* Counter32 */
- {ASN1_APL, SNMP_GGE, SNMP_GAUGE}, /* Gauge32 == Unsigned32 */
- {ASN1_APL, SNMP_TIT, SNMP_TIMETICKS},
- {ASN1_APL, SNMP_OPQ, SNMP_OPAQUE},
-
- /* SNMPv2 data types and errors */
- {ASN1_UNI, ASN1_BTS, SNMP_BITSTR},
- {ASN1_APL, SNMP_C64, SNMP_COUNTER64},
- {ASN1_CTX, SERR_NSO, SNMP_NOSUCHOBJECT},
- {ASN1_CTX, SERR_NSI, SNMP_NOSUCHINSTANCE},
- {ASN1_CTX, SERR_EOM, SNMP_ENDOFMIBVIEW},
- {0, 0, -1}
-};
-
-static unsigned char snmp_tag_cls2syntax(unsigned int tag,
- unsigned int cls,
- unsigned short *syntax)
-{
- const struct snmp_cnv *cnv;
-
- cnv = snmp_conv;
-
- while (cnv->syntax != -1) {
- if (cnv->tag == tag && cnv->class == cls) {
- *syntax = cnv->syntax;
- return 1;
- }
- cnv++;
- }
- return 0;
-}
-
-static unsigned char snmp_object_decode(struct asn1_ctx *ctx,
- struct snmp_object **obj)
-{
- unsigned int cls, con, tag, len, idlen;
- unsigned short type;
- unsigned char *eoc, *end, *p;
- unsigned long *lp, *id;
- unsigned long ul;
- long l;
-
- *obj = NULL;
- id = NULL;
-
- if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
- return 0;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
- return 0;
-
- if (!asn1_oid_decode(ctx, end, &id, &idlen))
- return 0;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) {
- kfree(id);
- return 0;
- }
-
- if (con != ASN1_PRI) {
- kfree(id);
- return 0;
- }
-
- type = 0;
- if (!snmp_tag_cls2syntax(tag, cls, &type)) {
- kfree(id);
- return 0;
- }
-
- l = 0;
- switch (type) {
- case SNMP_INTEGER:
- len = sizeof(long);
- if (!asn1_long_decode(ctx, end, &l)) {
- kfree(id);
- return 0;
- }
- *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
- if (*obj == NULL) {
- kfree(id);
- return 0;
- }
- (*obj)->syntax.l[0] = l;
- break;
- case SNMP_OCTETSTR:
- case SNMP_OPAQUE:
- if (!asn1_octets_decode(ctx, end, &p, &len)) {
- kfree(id);
- return 0;
- }
- *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
- if (*obj == NULL) {
- kfree(p);
- kfree(id);
- return 0;
- }
- memcpy((*obj)->syntax.c, p, len);
- kfree(p);
- break;
- case SNMP_NULL:
- case SNMP_NOSUCHOBJECT:
- case SNMP_NOSUCHINSTANCE:
- case SNMP_ENDOFMIBVIEW:
- len = 0;
- *obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
- if (*obj == NULL) {
- kfree(id);
- return 0;
- }
- if (!asn1_null_decode(ctx, end)) {
- kfree(id);
- kfree(*obj);
- *obj = NULL;
- return 0;
- }
- break;
- case SNMP_OBJECTID:
- if (!asn1_oid_decode(ctx, end, &lp, &len)) {
- kfree(id);
- return 0;
- }
- len *= sizeof(unsigned long);
- *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
- if (*obj == NULL) {
- kfree(lp);
- kfree(id);
- return 0;
- }
- memcpy((*obj)->syntax.ul, lp, len);
- kfree(lp);
- break;
- case SNMP_IPADDR:
- if (!asn1_octets_decode(ctx, end, &p, &len)) {
- kfree(id);
- return 0;
- }
- if (len != 4) {
- kfree(p);
- kfree(id);
- return 0;
- }
- *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
- if (*obj == NULL) {
- kfree(p);
- kfree(id);
- return 0;
- }
- memcpy((*obj)->syntax.uc, p, len);
- kfree(p);
- break;
- case SNMP_COUNTER:
- case SNMP_GAUGE:
- case SNMP_TIMETICKS:
- len = sizeof(unsigned long);
- if (!asn1_ulong_decode(ctx, end, &ul)) {
- kfree(id);
- return 0;
- }
- *obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
- if (*obj == NULL) {
- kfree(id);
- return 0;
- }
- (*obj)->syntax.ul[0] = ul;
- break;
- default:
- kfree(id);
- return 0;
- }
-
- (*obj)->syntax_len = len;
- (*obj)->type = type;
- (*obj)->id = id;
- (*obj)->id_len = idlen;
-
- if (!asn1_eoc_decode(ctx, eoc)) {
- kfree(id);
- kfree(*obj);
- *obj = NULL;
- return 0;
- }
- return 1;
-}
-
-static unsigned char noinline_for_stack
-snmp_request_decode(struct asn1_ctx *ctx, struct snmp_request *request)
-{
- unsigned int cls, con, tag;
- unsigned char *end;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
- return 0;
-
- if (!asn1_ulong_decode(ctx, end, &request->id))
- return 0;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
- return 0;
-
- if (!asn1_uint_decode(ctx, end, &request->error_status))
- return 0;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
- return 0;
-
- if (!asn1_uint_decode(ctx, end, &request->error_index))
- return 0;
-
- return 1;
-}
-
-/*
- * Fast checksum update for possibly oddly-aligned UDP byte, from the
- * code example in the draft.
- */
-static void fast_csum(__sum16 *csum,
- const unsigned char *optr,
- const unsigned char *nptr,
- int offset)
-{
- unsigned char s[4];
-
- if (offset & 1) {
- s[0] = ~0;
- s[1] = ~*optr;
- s[2] = 0;
- s[3] = *nptr;
- } else {
- s[0] = ~*optr;
- s[1] = ~0;
- s[2] = *nptr;
- s[3] = 0;
- }
-
- *csum = csum_fold(csum_partial(s, 4, ~csum_unfold(*csum)));
-}
-
-/*
- * Mangle IP address.
- * - begin points to the start of the snmp messgae
- * - addr points to the start of the address
- */
-static inline void mangle_address(unsigned char *begin,
- unsigned char *addr,
- const struct oct1_map *map,
- __sum16 *check)
-{
- if (map->from == NOCT1(addr)) {
- *addr = map->to;
-
- /* Update UDP checksum if being used */
- if (*check) {
- fast_csum(check,
- &map->from, &map->to, addr - begin);
- }
- }
-}
-
-static unsigned char noinline_for_stack
-snmp_trap_decode(struct asn1_ctx *ctx, struct snmp_v1_trap *trap,
- const struct oct1_map *map,
- __sum16 *check)
-{
- unsigned int cls, con, tag, len;
- unsigned char *end;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
- return 0;
-
- if (!asn1_oid_decode(ctx, end, &trap->id, &trap->id_len))
- return 0;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- goto err_id_free;
-
- if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_IPA) ||
- (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_OTS)))
- goto err_id_free;
-
- if (!asn1_octets_decode(ctx, end, (unsigned char **)&trap->ip_address, &len))
- goto err_id_free;
-
- /* IPv4 only */
- if (len != 4)
- goto err_addr_free;
-
- mangle_address(ctx->begin, ctx->pointer - 4, map, check);
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- goto err_addr_free;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
- goto err_addr_free;
-
- if (!asn1_uint_decode(ctx, end, &trap->general))
- goto err_addr_free;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- goto err_addr_free;
-
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
- goto err_addr_free;
-
- if (!asn1_uint_decode(ctx, end, &trap->specific))
- goto err_addr_free;
-
- if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
- goto err_addr_free;
-
- if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_TIT) ||
- (cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_INT)))
- goto err_addr_free;
-
- if (!asn1_ulong_decode(ctx, end, &trap->time))
- goto err_addr_free;
-
- return 1;
-
-err_addr_free:
- kfree((unsigned long *)trap->ip_address);
-
-err_id_free:
- kfree(trap->id);
-
- return 0;
-}
-
-/*
- * Parse and mangle SNMP message according to mapping.
- * (And this is the fucking 'basic' method).
- */
-static int snmp_parse_mangle(unsigned char *msg,
- u_int16_t len,
- const struct oct1_map *map,
- __sum16 *check)
-{
- unsigned char *eoc, *end;
- unsigned int cls, con, tag, vers, pdutype;
- struct asn1_ctx ctx;
- struct asn1_octstr comm;
- struct snmp_object *obj;
-
- asn1_open(&ctx, msg, len);
-
- /*
- * Start of SNMP message.
- */
- if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
- return 0;
- if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
- return 0;
-
- /*
- * Version 1 or 2 handled.
- */
- if (!asn1_header_decode(&ctx, &end, &cls, &con, &tag))
- return 0;
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
- return 0;
- if (!asn1_uint_decode (&ctx, end, &vers))
- return 0;
- if (vers > 1)
- return 1;
-
- /*
- * Community.
- */
- if (!asn1_header_decode (&ctx, &end, &cls, &con, &tag))
- return 0;
- if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OTS)
- return 0;
- if (!asn1_octets_decode(&ctx, end, &comm.data, &comm.len))
- return 0;
- kfree(comm.data);
-
- /*
- * PDU type
- */
- if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &pdutype))
- return 0;
- if (cls != ASN1_CTX || con != ASN1_CON)
- return 0;
- if (pdutype != SNMP_PDU_RESPONSE &&
- pdutype != SNMP_PDU_TRAP1 && pdutype != SNMP_PDU_TRAP2)
- return 1;
-
- /*
- * Request header or v1 trap
- */
- if (pdutype == SNMP_PDU_TRAP1) {
- struct snmp_v1_trap trap;
- unsigned char ret = snmp_trap_decode(&ctx, &trap, map, check);
-
- if (ret) {
- kfree(trap.id);
- kfree((unsigned long *)trap.ip_address);
- } else
- return ret;
-
- } else {
- struct snmp_request req;
-
- if (!snmp_request_decode(&ctx, &req))
- return 0;
- }
-
- /*
- * Loop through objects, look for IP addresses to mangle.
- */
- if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
- return 0;
-
- if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
- return 0;
-
- while (!asn1_eoc_decode(&ctx, eoc)) {
- if (!snmp_object_decode(&ctx, &obj)) {
- if (obj) {
- kfree(obj->id);
- kfree(obj);
- }
- return 0;
- }
-
- if (obj->type == SNMP_IPADDR)
- mangle_address(ctx.begin, ctx.pointer - 4, map, check);
-
- kfree(obj->id);
- kfree(obj);
- }
-
- if (!asn1_eoc_decode(&ctx, eoc))
- return 0;
-
- return 1;
-}
-
-/*
- * SNMP translation routine.
- */
-static int snmp_translate(struct nf_conn *ct, int dir, struct sk_buff *skb)
-{
- struct iphdr *iph = ip_hdr(skb);
- struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
- u_int16_t udplen = ntohs(udph->len);
- u_int16_t paylen = udplen - sizeof(struct udphdr);
- struct oct1_map map;
-
- /*
- * Determine mappping for application layer addresses based
- * on NAT manipulations for the packet.
- */
- if (dir == IP_CT_DIR_ORIGINAL) {
- /* SNAT traps */
- map.from = NOCT1(&ct->tuplehash[dir].tuple.src.u3.ip);
- map.to = NOCT1(&ct->tuplehash[!dir].tuple.dst.u3.ip);
- } else {
- /* DNAT replies */
- map.from = NOCT1(&ct->tuplehash[!dir].tuple.src.u3.ip);
- map.to = NOCT1(&ct->tuplehash[dir].tuple.dst.u3.ip);
- }
-
- if (map.from == map.to)
- return NF_ACCEPT;
-
- if (!snmp_parse_mangle((unsigned char *)udph + sizeof(struct udphdr),
- paylen, &map, &udph->check)) {
- nf_ct_helper_log(skb, ct, "parser failed\n");
- return NF_DROP;
- }
- return NF_ACCEPT;
-}
-
-/* We don't actually set up expectations, just adjust internal IP
- * addresses if this is being NATted */
-static int help(struct sk_buff *skb, unsigned int protoff,
- struct nf_conn *ct,
- enum ip_conntrack_info ctinfo)
-{
- int dir = CTINFO2DIR(ctinfo);
- unsigned int ret;
- const struct iphdr *iph = ip_hdr(skb);
- const struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
-
- /* SNMP replies and originating SNMP traps get mangled */
- if (udph->source == htons(SNMP_PORT) && dir != IP_CT_DIR_REPLY)
- return NF_ACCEPT;
- if (udph->dest == htons(SNMP_TRAP_PORT) && dir != IP_CT_DIR_ORIGINAL)
- return NF_ACCEPT;
-
- /* No NAT? */
- if (!(ct->status & IPS_NAT_MASK))
- return NF_ACCEPT;
-
- /*
- * Make sure the packet length is ok. So far, we were only guaranteed
- * to have a valid length IP header plus 8 bytes, which means we have
- * enough room for a UDP header. Just verify the UDP length field so we
- * can mess around with the payload.
- */
- if (ntohs(udph->len) != skb->len - (iph->ihl << 2)) {
- nf_ct_helper_log(skb, ct, "dropping malformed packet\n");
- return NF_DROP;
- }
-
- if (!skb_make_writable(skb, skb->len)) {
- nf_ct_helper_log(skb, ct, "cannot mangle packet");
- return NF_DROP;
- }
-
- spin_lock_bh(&snmp_lock);
- ret = snmp_translate(ct, dir, skb);
- spin_unlock_bh(&snmp_lock);
- return ret;
-}
-
-static const struct nf_conntrack_expect_policy snmp_exp_policy = {
- .max_expected = 0,
- .timeout = 180,
-};
-
-static struct nf_conntrack_helper snmp_trap_helper __read_mostly = {
- .me = THIS_MODULE,
- .help = help,
- .expect_policy = &snmp_exp_policy,
- .name = "snmp_trap",
- .tuple.src.l3num = AF_INET,
- .tuple.src.u.udp.port = cpu_to_be16(SNMP_TRAP_PORT),
- .tuple.dst.protonum = IPPROTO_UDP,
-};
-
-static int __init nf_nat_snmp_basic_init(void)
-{
- BUG_ON(nf_nat_snmp_hook != NULL);
- RCU_INIT_POINTER(nf_nat_snmp_hook, help);
-
- return nf_conntrack_helper_register(&snmp_trap_helper);
-}
-
-static void __exit nf_nat_snmp_basic_fini(void)
-{
- RCU_INIT_POINTER(nf_nat_snmp_hook, NULL);
- synchronize_rcu();
- nf_conntrack_helper_unregister(&snmp_trap_helper);
-}
-
-module_init(nf_nat_snmp_basic_init);
-module_exit(nf_nat_snmp_basic_fini);
--- /dev/null
+/*
+ * nf_nat_snmp_basic.c
+ *
+ * Basic SNMP Application Layer Gateway
+ *
+ * This IP NAT module is intended for use with SNMP network
+ * discovery and monitoring applications where target networks use
+ * conflicting private address realms.
+ *
+ * Static NAT is used to remap the networks from the view of the network
+ * management system at the IP layer, and this module remaps some application
+ * layer addresses to match.
+ *
+ * The simplest form of ALG is performed, where only tagged IP addresses
+ * are modified. The module does not need to be MIB aware and only scans
+ * messages at the ASN.1/BER level.
+ *
+ * Currently, only SNMPv1 and SNMPv2 are supported.
+ *
+ * More information on ALG and associated issues can be found in
+ * RFC 2962
+ *
+ * The ASB.1/BER parsing code is derived from the gxsnmp package by Gregory
+ * McLean & Jochen Friedrich, stripped down for use in the kernel.
+ *
+ * Copyright (c) 2000 RP Internet (www.rpi.net.au).
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: James Morris <jmorris@intercode.com.au>
+ *
+ * Copyright (c) 2006-2010 Patrick McHardy <kaber@trash.net>
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <net/checksum.h>
+#include <net/udp.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <linux/netfilter/nf_conntrack_snmp.h>
+#include "nf_nat_snmp_basic-asn1.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
+MODULE_DESCRIPTION("Basic SNMP Application Layer Gateway");
+MODULE_ALIAS("ip_nat_snmp_basic");
+
+#define SNMP_PORT 161
+#define SNMP_TRAP_PORT 162
+
+static DEFINE_SPINLOCK(snmp_lock);
+
+struct snmp_ctx {
+ unsigned char *begin;
+ __sum16 *check;
+ __be32 from;
+ __be32 to;
+};
+
+static void fast_csum(struct snmp_ctx *ctx, unsigned char offset)
+{
+ unsigned char s[12] = {0,};
+ int size;
+
+ if (offset & 1) {
+ memcpy(&s[1], &ctx->from, 4);
+ memcpy(&s[7], &ctx->to, 4);
+ s[0] = ~0;
+ s[1] = ~s[1];
+ s[2] = ~s[2];
+ s[3] = ~s[3];
+ s[4] = ~s[4];
+ s[5] = ~0;
+ size = 12;
+ } else {
+ memcpy(&s[0], &ctx->from, 4);
+ memcpy(&s[4], &ctx->to, 4);
+ s[0] = ~s[0];
+ s[1] = ~s[1];
+ s[2] = ~s[2];
+ s[3] = ~s[3];
+ size = 8;
+ }
+ *ctx->check = csum_fold(csum_partial(s, size,
+ ~csum_unfold(*ctx->check)));
+}
+
+int snmp_version(void *context, size_t hdrlen, unsigned char tag,
+ const void *data, size_t datalen)
+{
+ if (*(unsigned char *)data > 1)
+ return -ENOTSUPP;
+ return 1;
+}
+
+int snmp_helper(void *context, size_t hdrlen, unsigned char tag,
+ const void *data, size_t datalen)
+{
+ struct snmp_ctx *ctx = (struct snmp_ctx *)context;
+ __be32 *pdata = (__be32 *)data;
+
+ if (*pdata == ctx->from) {
+ pr_debug("%s: %pI4 to %pI4\n", __func__,
+ (void *)&ctx->from, (void *)&ctx->to);
+
+ if (*ctx->check)
+ fast_csum(ctx, (unsigned char *)data - ctx->begin);
+ *pdata = ctx->to;
+ }
+
+ return 1;
+}
+
+static int snmp_translate(struct nf_conn *ct, int dir, struct sk_buff *skb)
+{
+ struct iphdr *iph = ip_hdr(skb);
+ struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
+ u16 datalen = ntohs(udph->len) - sizeof(struct udphdr);
+ char *data = (unsigned char *)udph + sizeof(struct udphdr);
+ struct snmp_ctx ctx;
+ int ret;
+
+ if (dir == IP_CT_DIR_ORIGINAL) {
+ ctx.from = ct->tuplehash[dir].tuple.src.u3.ip;
+ ctx.to = ct->tuplehash[!dir].tuple.dst.u3.ip;
+ } else {
+ ctx.from = ct->tuplehash[!dir].tuple.src.u3.ip;
+ ctx.to = ct->tuplehash[dir].tuple.dst.u3.ip;
+ }
+
+ if (ctx.from == ctx.to)
+ return NF_ACCEPT;
+
+ ctx.begin = (unsigned char *)udph + sizeof(struct udphdr);
+ ctx.check = &udph->check;
+ ret = asn1_ber_decoder(&nf_nat_snmp_basic_decoder, &ctx, data, datalen);
+ if (ret < 0) {
+ nf_ct_helper_log(skb, ct, "parser failed\n");
+ return NF_DROP;
+ }
+
+ return NF_ACCEPT;
+}
+
+/* We don't actually set up expectations, just adjust internal IP
+ * addresses if this is being NATted
+ */
+static int help(struct sk_buff *skb, unsigned int protoff,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ unsigned int ret;
+ const struct iphdr *iph = ip_hdr(skb);
+ const struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
+
+ /* SNMP replies and originating SNMP traps get mangled */
+ if (udph->source == htons(SNMP_PORT) && dir != IP_CT_DIR_REPLY)
+ return NF_ACCEPT;
+ if (udph->dest == htons(SNMP_TRAP_PORT) && dir != IP_CT_DIR_ORIGINAL)
+ return NF_ACCEPT;
+
+ /* No NAT? */
+ if (!(ct->status & IPS_NAT_MASK))
+ return NF_ACCEPT;
+
+ /* Make sure the packet length is ok. So far, we were only guaranteed
+ * to have a valid length IP header plus 8 bytes, which means we have
+ * enough room for a UDP header. Just verify the UDP length field so we
+ * can mess around with the payload.
+ */
+ if (ntohs(udph->len) != skb->len - (iph->ihl << 2)) {
+ nf_ct_helper_log(skb, ct, "dropping malformed packet\n");
+ return NF_DROP;
+ }
+
+ if (!skb_make_writable(skb, skb->len)) {
+ nf_ct_helper_log(skb, ct, "cannot mangle packet");
+ return NF_DROP;
+ }
+
+ spin_lock_bh(&snmp_lock);
+ ret = snmp_translate(ct, dir, skb);
+ spin_unlock_bh(&snmp_lock);
+ return ret;
+}
+
+static const struct nf_conntrack_expect_policy snmp_exp_policy = {
+ .max_expected = 0,
+ .timeout = 180,
+};
+
+static struct nf_conntrack_helper snmp_trap_helper __read_mostly = {
+ .me = THIS_MODULE,
+ .help = help,
+ .expect_policy = &snmp_exp_policy,
+ .name = "snmp_trap",
+ .tuple.src.l3num = AF_INET,
+ .tuple.src.u.udp.port = cpu_to_be16(SNMP_TRAP_PORT),
+ .tuple.dst.protonum = IPPROTO_UDP,
+};
+
+static int __init nf_nat_snmp_basic_init(void)
+{
+ BUG_ON(nf_nat_snmp_hook != NULL);
+ RCU_INIT_POINTER(nf_nat_snmp_hook, help);
+
+ return nf_conntrack_helper_register(&snmp_trap_helper);
+}
+
+static void __exit nf_nat_snmp_basic_fini(void)
+{
+ RCU_INIT_POINTER(nf_nat_snmp_hook, NULL);
+ synchronize_rcu();
+ nf_conntrack_helper_unregister(&snmp_trap_helper);
+}
+
+module_init(nf_nat_snmp_basic_init);
+module_exit(nf_nat_snmp_basic_fini);
projects / platform / kernel / linux-rpi3.git / commitdiff