Commit cc2d5863 authored by Taehee Yoo's avatar Taehee Yoo Committed by Pablo Neira Ayuso
Browse files

netfilter: nf_nat_snmp_basic: use asn1 decoder library 



The basic SNMP ALG parse snmp ASN.1 payload
however, since 2012 linux kernel provide ASN.1 decoder library.
If we use ASN.1 decoder in the /lib/asn1_decoder.c, we can remove
about 1000 line of ASN.1 parsing routine.

To use asn1_decoder.c, we should write mib file(nf_nat_snmp_basic.asn1)
then /script/asn1_compiler.c makes *-asn1.c and *-asn1.h file
at the compiletime.(nf_nat_snmp_basic-asn1.c, nf_nat_snmp_basic-asn1.h)
The nf_nat_snmp_basic.asn1 is made by RFC1155, RFC1157, RFC1902, RFC1905,
RFC2578, RFC3416. of course that mib file supports only the basic SNMP ALG.

Previous SNMP ALG mangles only first octet of IPv4 address.
but after this patch, the SNMP ALG mangles whole IPv4 Address.
And SNMPv3 is not supported.

I tested with snmp commands such ans snmpd, snmpwalk, snmptrap.

Signed-off-by: default avatarTaehee Yoo <ap420073@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent bea588b0

net/ipv4/netfilter/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -158,6 +158,7 @@ config NF_NAT_SNMP_BASIC 
	depends on NF_CONNTRACK_SNMP

	depends on NETFILTER_ADVANCED

	default NF_NAT && NF_CONNTRACK_SNMP

	select ASN1

	---help---



	  This module implements an Application Layer Gateway (ALG) for

net/ipv4/netfilter/Makefile

+6 −0
Original line number Diff line number Diff line
@@ -27,9 +27,15 @@ obj-$(CONFIG_NF_REJECT_IPV4) += nf_reject_ipv4.o 
# NAT helpers (nf_conntrack)

obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o

obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o



nf_nat_snmp_basic-y := nf_nat_snmp_basic-asn1.o nf_nat_snmp_basic_main.o

nf_nat_snmp_basic-y : nf_nat_snmp_basic-asn1.h nf_nat_snmp_basic-asn1.c

obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o

clean-files := nf_nat_snmp_basic-asn1.c nf_nat_snmp_basic-asn1.h



obj-$(CONFIG_NF_NAT_MASQUERADE_IPV4) += nf_nat_masquerade_ipv4.o





# NAT protocols (nf_nat)

obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o

net/ipv4/netfilter/nf_nat_snmp_basic.asn1

0 → 100644
+177 −0
Original line number Diff line number Diff line 
Message ::=

	SEQUENCE {

		version

			INTEGER ({snmp_version}),



		community

			OCTET STRING,



		pdu

			PDUs

	}





ObjectName ::=

	OBJECT IDENTIFIER



ObjectSyntax ::=

	CHOICE {

		simple

			SimpleSyntax,



		application-wide

			ApplicationSyntax

	}



SimpleSyntax ::=

	CHOICE {

		integer-value

			INTEGER,



		string-value

			OCTET STRING,



		objectID-value

			OBJECT IDENTIFIER

	}



ApplicationSyntax ::=

	CHOICE {

		ipAddress-value

			IpAddress,



		counter-value

			Counter32,



		timeticks-value

			TimeTicks,



		arbitrary-value

			Opaque,



		big-counter-value

			Counter64,



		unsigned-integer-value

			Unsigned32

	}



IpAddress ::=

	[APPLICATION 0]

		IMPLICIT OCTET STRING OPTIONAL ({snmp_helper})



Counter32 ::=

	[APPLICATION 1]

		IMPLICIT INTEGER OPTIONAL



Unsigned32 ::=

	[APPLICATION 2]

		IMPLICIT INTEGER OPTIONAL



Gauge32 ::= Unsigned32 OPTIONAL



TimeTicks ::=

	[APPLICATION 3]

		IMPLICIT INTEGER OPTIONAL



Opaque ::=

	[APPLICATION 4]

		IMPLICIT OCTET STRING OPTIONAL



Counter64 ::=

	[APPLICATION 6]

		IMPLICIT INTEGER OPTIONAL



PDUs ::=

	CHOICE {

		get-request

			GetRequest-PDU,



		get-next-request

			GetNextRequest-PDU,



		get-bulk-request

			GetBulkRequest-PDU,



		response

			Response-PDU,



		set-request

			SetRequest-PDU,



		inform-request

			InformRequest-PDU,



		snmpV2-trap

			SNMPv2-Trap-PDU,



		report

			Report-PDU

	}



GetRequest-PDU ::=

	[0] IMPLICIT PDU OPTIONAL



GetNextRequest-PDU ::=

	[1] IMPLICIT PDU OPTIONAL



Response-PDU ::=

	[2] IMPLICIT PDU OPTIONAL



SetRequest-PDU ::=

	[3] IMPLICIT PDU OPTIONAL



-- [4] is obsolete



GetBulkRequest-PDU ::=

	[5] IMPLICIT PDU OPTIONAL



InformRequest-PDU ::=

	[6] IMPLICIT PDU OPTIONAL



SNMPv2-Trap-PDU ::=

	[7] IMPLICIT PDU OPTIONAL



Report-PDU ::=

	[8] IMPLICIT PDU OPTIONAL



PDU ::=

	SEQUENCE {

		request-id

			INTEGER,



		error-status

			INTEGER,



		error-index

			INTEGER,



		variable-bindings

			VarBindList

	}





VarBind ::=

	SEQUENCE {

		name

			ObjectName,



	CHOICE {

		value

			ObjectSyntax,



		unSpecified

			NULL,



		noSuchObject

			[0] IMPLICIT NULL,



		noSuchInstance

			[1] IMPLICIT NULL,



		endOfMibView

			[2] IMPLICIT NULL

	}

}



VarBindList ::= SEQUENCE OF VarBind

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