diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_nat_snmp_basic.c')
| -rw-r--r-- | net/ipv4/netfilter/nf_nat_snmp_basic.c | 1286 |
1 files changed, 0 insertions, 1286 deletions
diff --git a/net/ipv4/netfilter/nf_nat_snmp_basic.c b/net/ipv4/netfilter/nf_nat_snmp_basic.c deleted file mode 100644 index d5b1e0b3f687..000000000000 --- a/net/ipv4/netfilter/nf_nat_snmp_basic.c +++ /dev/null @@ -1,1286 +0,0 @@ -/* - * 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 int debug; -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; -}; - - -/***************************************************************************** - * - * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse) - * - *****************************************************************************/ - -/* 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 decoding routines (gxsnmp author Dirk Wisse) - * - *****************************************************************************/ - -/* 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)) { - u_int32_t old; - - if (debug) - memcpy(&old, addr, sizeof(old)); - - *addr = map->to; - - /* Update UDP checksum if being used */ - if (*check) { - fast_csum(check, - &map->from, &map->to, addr - begin); - - } - - if (debug) - printk(KERN_DEBUG "bsalg: mapped %pI4 to %pI4\n", - &old, addr); - } -} - -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; -} - -/***************************************************************************** - * - * Misc. routines - * - *****************************************************************************/ - -/* - * 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; - - if (debug > 1) - print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 16, 1, - msg, len, 0); - - 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 (debug > 1) - pr_debug("bsalg: snmp version: %u\n", vers + 1); - 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; - if (debug > 1) { - unsigned int i; - - pr_debug("bsalg: community: "); - for (i = 0; i < comm.len; i++) - pr_cont("%c", comm.data[i]); - pr_cont("\n"); - } - 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 (debug > 1) { - static const unsigned char *const pdus[] = { - [SNMP_PDU_GET] = "get", - [SNMP_PDU_NEXT] = "get-next", - [SNMP_PDU_RESPONSE] = "response", - [SNMP_PDU_SET] = "set", - [SNMP_PDU_TRAP1] = "trapv1", - [SNMP_PDU_BULK] = "bulk", - [SNMP_PDU_INFORM] = "inform", - [SNMP_PDU_TRAP2] = "trapv2" - }; - - if (pdutype > SNMP_PDU_TRAP2) - pr_debug("bsalg: bad pdu type %u\n", pdutype); - else - pr_debug("bsalg: pdu: %s\n", pdus[pdutype]); - } - 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; - - if (debug > 1) - pr_debug("bsalg: request: id=0x%lx error_status=%u " - "error_index=%u\n", req.id, req.error_status, - req.error_index); - } - - /* - * 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)) { - unsigned int i; - - if (!snmp_object_decode(&ctx, &obj)) { - if (obj) { - kfree(obj->id); - kfree(obj); - } - return 0; - } - - if (debug > 1) { - pr_debug("bsalg: object: "); - for (i = 0; i < obj->id_len; i++) { - if (i > 0) - pr_cont("."); - pr_cont("%lu", obj->id[i]); - } - pr_cont(": type=%u\n", obj->type); - - } - - 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; -} - -/***************************************************************************** - * - * NAT routines. - * - *****************************************************************************/ - -/* - * SNMP translation routine. - */ -static int snmp_translate(struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - 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); - int dir = CTINFO2DIR(ctinfo); - 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)) { - net_warn_ratelimited("bsalg: 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)) { - net_warn_ratelimited("SNMP: dropping malformed packet src=%pI4 dst=%pI4\n", - &iph->saddr, &iph->daddr); - return NF_DROP; - } - - if (!skb_make_writable(skb, skb->len)) - return NF_DROP; - - spin_lock_bh(&snmp_lock); - ret = snmp_translate(ct, ctinfo, 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, -}; - -/***************************************************************************** - * - * Module stuff. - * - *****************************************************************************/ - -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); - -module_param(debug, int, 0600); |