010dabb047
comes in on is the same interface that we would route out of to get to the packet's source address. Essentially automates an anti-spoofing check using the information in the routing table. Experimental. The usage and rule format for the feature may still be subject to change.
409 lines
12 KiB
C
409 lines
12 KiB
C
/*
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* Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _IPFW2_H
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#define _IPFW2_H
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#define IPFW2 1
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/*
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* The kernel representation of ipfw rules is made of a list of
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* 'instructions' (for all practical purposes equivalent to BPF
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* instructions), which specify which fields of the packet
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* (or its metatada) should be analysed.
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*
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* Each instruction is stored in a structure which begins with
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* "ipfw_insn", and can contain extra fields depending on the
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* instruction type (listed below).
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*
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* "enum ipfw_opcodes" are the opcodes supported. We can have up
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* to 256 different opcodes.
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*/
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enum ipfw_opcodes { /* arguments (4 byte each) */
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O_NOP,
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O_IP_SRC, /* u32 = IP */
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O_IP_SRC_MASK, /* ip = IP/mask */
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O_IP_SRC_ME, /* none */
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O_IP_SRC_SET, /* u32=base, arg1=len, bitmap */
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O_IP_DST, /* u32 = IP */
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O_IP_DST_MASK, /* ip = IP/mask */
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O_IP_DST_ME, /* none */
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O_IP_DST_SET, /* u32=base, arg1=len, bitmap */
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O_IP_SRCPORT, /* (n)port list:mask 4 byte ea */
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O_IP_DSTPORT, /* (n)port list:mask 4 byte ea */
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O_PROTO, /* arg1=protocol */
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O_MACADDR2, /* 2 mac addr:mask */
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O_MAC_TYPE, /* same as srcport */
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O_LAYER2, /* none */
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O_IN, /* none */
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O_FRAG, /* none */
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O_RECV, /* none */
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O_XMIT, /* none */
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O_VIA, /* none */
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O_IPOPT, /* arg1 = 2*u8 bitmap */
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O_IPLEN, /* arg1 = len */
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O_IPID, /* arg1 = id */
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O_IPTOS, /* arg1 = id */
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O_IPPRECEDENCE, /* arg1 = precedence << 5 */
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O_IPTTL, /* arg1 = TTL */
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O_IPVER, /* arg1 = version */
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O_UID, /* u32 = id */
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O_GID, /* u32 = id */
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O_ESTAB, /* none (tcp established) */
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O_TCPFLAGS, /* arg1 = 2*u8 bitmap */
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O_TCPWIN, /* arg1 = desired win */
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O_TCPSEQ, /* u32 = desired seq. */
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O_TCPACK, /* u32 = desired seq. */
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O_ICMPTYPE, /* u32 = icmp bitmap */
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O_TCPOPTS, /* arg1 = 2*u8 bitmap */
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O_VERREVPATH, /* none */
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O_PROBE_STATE, /* none */
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O_KEEP_STATE, /* none */
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O_LIMIT, /* ipfw_insn_limit */
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O_LIMIT_PARENT, /* dyn_type, not an opcode. */
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/*
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* these are really 'actions', and must be last in the list.
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*/
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O_LOG, /* ipfw_insn_log */
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O_PROB, /* u32 = match probability */
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O_CHECK_STATE, /* none */
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O_ACCEPT, /* none */
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O_DENY, /* none */
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O_REJECT, /* arg1=icmp arg (same as deny) */
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O_COUNT, /* none */
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O_SKIPTO, /* arg1=next rule number */
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O_PIPE, /* arg1=pipe number */
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O_QUEUE, /* arg1=queue number */
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O_DIVERT, /* arg1=port number */
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O_TEE, /* arg1=port number */
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O_FORWARD_IP, /* fwd sockaddr */
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O_FORWARD_MAC, /* fwd mac */
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O_LAST_OPCODE /* not an opcode! */
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};
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/*
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* Template for instructions.
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*
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* ipfw_insn is used for all instructions which require no operands,
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* a single 16-bit value (arg1), or a couple of 8-bit values.
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*
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* For other instructions which require different/larger arguments
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* we have derived structures, ipfw_insn_*.
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*
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* The size of the instruction (in 32-bit words) is in the low
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* 6 bits of "len". The 2 remaining bits are used to implement
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* NOT and OR on individual instructions. Given a type, you can
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* compute the length to be put in "len" using F_INSN_SIZE(t)
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*
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* F_NOT negates the match result of the instruction.
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*
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* F_OR is used to build or blocks. By default, instructions
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* are evaluated as part of a logical AND. An "or" block
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* { X or Y or Z } contains F_OR set in all but the last
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* instruction of the block. A match will cause the code
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* to skip past the last instruction of the block.
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*
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* NOTA BENE: in a couple of places we assume that
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* sizeof(ipfw_insn) == sizeof(u_int32_t)
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* this needs to be fixed.
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*
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*/
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typedef struct _ipfw_insn { /* template for instructions */
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enum ipfw_opcodes opcode:8;
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u_int8_t len; /* numer of 32-byte words */
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#define F_NOT 0x80
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#define F_OR 0x40
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#define F_LEN_MASK 0x3f
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#define F_LEN(cmd) ((cmd)->len & F_LEN_MASK)
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u_int16_t arg1;
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} ipfw_insn;
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/*
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* The F_INSN_SIZE(type) computes the size, in 4-byte words, of
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* a given type.
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*/
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#define F_INSN_SIZE(t) ((sizeof (t))/sizeof(u_int32_t))
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/*
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* This is used to store an array of 16-bit entries (ports etc.)
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*/
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typedef struct _ipfw_insn_u16 {
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ipfw_insn o;
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u_int16_t ports[2]; /* there may be more */
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} ipfw_insn_u16;
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/*
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* This is used to store an array of 32-bit entries
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* (uid, single IPv4 addresses etc.)
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*/
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typedef struct _ipfw_insn_u32 {
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ipfw_insn o;
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u_int32_t d[1]; /* one or more */
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} ipfw_insn_u32;
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/*
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* This is used to store IP addr-mask pairs.
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*/
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typedef struct _ipfw_insn_ip {
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ipfw_insn o;
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struct in_addr addr;
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struct in_addr mask;
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} ipfw_insn_ip;
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/*
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* This is used to forward to a given address (ip)
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*/
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typedef struct _ipfw_insn_sa {
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ipfw_insn o;
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struct sockaddr_in sa;
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} ipfw_insn_sa;
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/*
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* This is used for MAC addr-mask pairs.
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*/
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typedef struct _ipfw_insn_mac {
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ipfw_insn o;
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u_char addr[12]; /* dst[6] + src[6] */
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u_char mask[12]; /* dst[6] + src[6] */
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} ipfw_insn_mac;
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/*
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* This is used for interface match rules (recv xx, xmit xx)
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*/
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typedef struct _ipfw_insn_if {
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ipfw_insn o;
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union {
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struct in_addr ip;
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int unit;
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} p;
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char name[IFNAMSIZ];
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} ipfw_insn_if;
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/*
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* This is used for pipe and queue actions, which need to store
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* a single pointer (which can have different size on different
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* architectures.
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*/
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typedef struct _ipfw_insn_pipe {
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ipfw_insn o;
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void *pipe_ptr;
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} ipfw_insn_pipe;
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/*
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* This is used for limit rules.
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*/
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typedef struct _ipfw_insn_limit {
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ipfw_insn o;
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u_int8_t _pad;
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u_int8_t limit_mask; /* combination of DYN_* below */
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#define DYN_SRC_ADDR 0x1
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#define DYN_SRC_PORT 0x2
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#define DYN_DST_ADDR 0x4
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#define DYN_DST_PORT 0x8
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u_int16_t conn_limit;
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} ipfw_insn_limit;
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/*
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* This is used for log instructions
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*/
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typedef struct _ipfw_insn_log {
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ipfw_insn o;
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u_int32_t max_log; /* how many do we log -- 0 = all */
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u_int32_t log_left; /* how many left to log */
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} ipfw_insn_log;
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/*
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* Here we have the structure representing an ipfw rule.
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*
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* It starts with a general area (with link fields and counters)
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* followed by an array of one or more instructions, which the code
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* accesses as an array of 32-bit values.
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*
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* Given a rule pointer r:
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*
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* r->cmd is the start of the first instruction.
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* ACTION_PTR(r) is the start of the first action (things to do
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* once a rule matched).
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*
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* When assembling instruction, remember the following:
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*
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* + if a rule has a "keep-state" (or "limit") option, then the
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* first instruction (at r->cmd) MUST BE an O_PROBE_STATE
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* + if a rule has a "log" option, then the first action
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* (at ACTION_PTR(r)) MUST be O_LOG
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*
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* NOTE: we use a simple linked list of rules because we never need
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* to delete a rule without scanning the list. We do not use
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* queue(3) macros for portability and readability.
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*/
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struct ip_fw {
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struct ip_fw *next; /* linked list of rules */
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struct ip_fw *next_rule; /* ptr to next [skipto] rule */
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u_int32_t set_disable; /* disabled sets (for userland) */
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u_int16_t act_ofs; /* offset of action in 32-bit units */
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u_int16_t cmd_len; /* # of 32-bit words in cmd */
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u_int16_t rulenum; /* rule number */
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u_int8_t set; /* rule set (0..31) */
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u_int8_t _pad; /* padding */
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/* These fields are present in all rules. */
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u_int64_t pcnt; /* Packet counter */
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u_int64_t bcnt; /* Byte counter */
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u_int32_t timestamp; /* tv_sec of last match */
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ipfw_insn cmd[1]; /* storage for commands */
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};
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#define ACTION_PTR(rule) \
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(ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) )
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#define RULESIZE(rule) (sizeof(struct ip_fw) + \
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((struct ip_fw *)(rule))->cmd_len * 4 - 4)
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/*
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* This structure is used as a flow mask and a flow id for various
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* parts of the code.
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*/
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struct ipfw_flow_id {
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u_int32_t dst_ip;
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u_int32_t src_ip;
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u_int16_t dst_port;
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u_int16_t src_port;
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u_int8_t proto;
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u_int8_t flags; /* protocol-specific flags */
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};
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/*
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* dynamic ipfw rule
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*/
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typedef struct _ipfw_dyn_rule ipfw_dyn_rule;
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struct _ipfw_dyn_rule {
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ipfw_dyn_rule *next; /* linked list of rules. */
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struct ipfw_flow_id id; /* (masked) flow id */
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struct ip_fw *rule; /* pointer to rule */
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ipfw_dyn_rule *parent; /* pointer to parent rule */
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u_int32_t expire; /* expire time */
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u_int64_t pcnt; /* packet match counter */
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u_int64_t bcnt; /* byte match counter */
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u_int32_t bucket; /* which bucket in hash table */
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u_int32_t state; /* state of this rule (typically a
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* combination of TCP flags)
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*/
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u_int32_t ack_fwd; /* most recent ACKs in forward */
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u_int32_t ack_rev; /* and reverse directions (used */
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/* to generate keepalives) */
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u_int16_t dyn_type; /* rule type */
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u_int16_t count; /* refcount */
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u_int16_t rulenum; /* rule number (for userland) */
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};
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/*
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* Definitions for IP option names.
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*/
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#define IP_FW_IPOPT_LSRR 0x01
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#define IP_FW_IPOPT_SSRR 0x02
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#define IP_FW_IPOPT_RR 0x04
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#define IP_FW_IPOPT_TS 0x08
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/*
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* Definitions for TCP option names.
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*/
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#define IP_FW_TCPOPT_MSS 0x01
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#define IP_FW_TCPOPT_WINDOW 0x02
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#define IP_FW_TCPOPT_SACK 0x04
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#define IP_FW_TCPOPT_TS 0x08
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#define IP_FW_TCPOPT_CC 0x10
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#define ICMP_REJECT_RST 0x100 /* fake ICMP code (send a TCP RST) */
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/*
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* Main firewall chains definitions and global var's definitions.
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*/
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#ifdef _KERNEL
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#define IP_FW_PORT_DYNT_FLAG 0x10000
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#define IP_FW_PORT_TEE_FLAG 0x20000
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#define IP_FW_PORT_DENY_FLAG 0x40000
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/*
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* arguments for calling ipfw_chk() and dummynet_io(). We put them
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* all into a structure because this way it is easier and more
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* efficient to pass variables around and extend the interface.
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*/
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struct ip_fw_args {
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struct mbuf *m; /* the mbuf chain */
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struct ifnet *oif; /* output interface */
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struct sockaddr_in *next_hop; /* forward address */
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struct ip_fw *rule; /* matching rule */
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struct ether_header *eh; /* for bridged packets */
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struct route *ro; /* for dummynet */
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struct sockaddr_in *dst; /* for dummynet */
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int flags; /* for dummynet */
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struct ipfw_flow_id f_id; /* grabbed from IP header */
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u_int16_t divert_rule; /* divert cookie */
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u_int32_t retval;
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};
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/*
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* Function definitions.
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*/
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/* Firewall hooks */
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struct sockopt;
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struct dn_flow_set;
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void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */
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typedef int ip_fw_chk_t (struct ip_fw_args *args);
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typedef int ip_fw_ctl_t (struct sockopt *);
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extern ip_fw_chk_t *ip_fw_chk_ptr;
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extern ip_fw_ctl_t *ip_fw_ctl_ptr;
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extern int fw_one_pass;
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extern int fw_enable;
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#define IPFW_LOADED (ip_fw_chk_ptr != NULL)
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#endif /* _KERNEL */
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#endif /* _IPFW2_H */
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