sys/netinet/ip_fw.h

/*
 * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: head/sys/netinet/ip_fw.h 98943 2002-06-27 23:02:18Z luigi $
 */

#ifndef _IPFW2_H
#define _IPFW2_H

/*
 * The kernel representation of ipfw rules is made of a list of
 * 'instructions' (for all practical purposes equivalent to BPF
 * instructions), which specify which fields of the packet
 * (or its metatada) should be analysed.
 *
 * Each instruction is stored in a structure which begins with
 * "ipfw_insn", and can contain extra fields depending on the
 * instruction type (listed below).
 *
 * "enum ipfw_opcodes" are the opcodes supported. We can have up
 * to 256 different opcodes.
 */

enum ipfw_opcodes {		/* arguments (4 byte each)	*/
	O_NOP,

	O_IP_SRC,		/* u32 = IP			*/
	O_IP_SRC_MASK,		/* ip = IP/mask			*/
	O_IP_SRC_ME,		/* none				*/
	O_IP_SRC_SET,		/* u32=base, arg1=len, bitmap	*/

	O_IP_DST,		/* u32 = IP			*/
	O_IP_DST_MASK,		/* ip = IP/mask			*/
	O_IP_DST_ME,		/* none				*/
	O_IP_DST_SET,		/* u32=base, arg1=len, bitmap	*/

	O_IP_SRCPORT,		/* (n)port list:mask 4 byte ea	*/
	O_IP_DSTPORT,		/* (n)port list:mask 4 byte ea	*/
	O_PROTO,		/* arg1=protocol		*/

	O_MACADDR2,		/* 2 mac addr:mask		*/
	O_MAC_TYPE,		/* same as srcport		*/

	O_LAYER2,		/* none				*/
	O_IN,			/* none				*/
	O_FRAG,			/* none				*/

	O_RECV,			/* none				*/
	O_XMIT,			/* none				*/
	O_VIA,			/* none				*/

	O_IPOPT,		/* arg1 = 2*u8 bitmap		*/
	O_IPLEN,		/* arg1 = len			*/
	O_IPID,			/* arg1 = id			*/

	O_IPPRE,		/* arg1 = id			*/
	O_IPTOS,		/* arg1 = id			*/
	O_IPTTL,		/* arg1 = TTL			*/

	O_IPVER,		/* arg1 = version		*/
	O_UID,			/* u32 = id			*/
	O_GID,			/* u32 = id			*/
	O_ESTAB,		/* none (tcp established)	*/
	O_TCPFLAGS,		/* arg1 = 2*u8 bitmap		*/
	O_TCPWIN,		/* arg1 = desired win		*/
	O_TCPSEQ,		/* u32 = desired seq.		*/
	O_TCPACK,		/* u32 = desired seq.		*/
	O_ICMPTYPE,		/* u32 = icmp bitmap		*/
	O_TCPOPTS,		/* arg1 = 2*u8 bitmap		*/
	O_IPOPTS,		/* arg1 = 2*u8 bitmap		*/

	O_PROBE_STATE,		/* none				*/
	O_KEEP_STATE,		/* none				*/
	O_LIMIT,		/* ipfw_insn_limit		*/
	O_LIMIT_PARENT,		/* dyn_type, not an opcode.	*/
	/*
	 * these are really 'actions', and must be last in the list.
	 */

	O_LOG,			/* ipfw_insn_log		*/
	O_PROB,			/* u32 = match probability	*/

	O_CHECK_STATE,		/* none				*/
	O_ACCEPT,		/* none				*/
	O_DENY,			/* none 			*/
	O_REJECT,		/* arg1=icmp arg (same as deny)	*/
	O_COUNT,		/* none				*/
	O_SKIPTO,		/* arg1=next rule number	*/
	O_PIPE,			/* arg1=pipe number		*/
	O_QUEUE,		/* arg1=queue number		*/
	O_DIVERT,		/* arg1=port number		*/
	O_TEE,			/* arg1=port number		*/
	O_FORWARD_IP,		/* fwd sockaddr			*/
	O_FORWARD_MAC,		/* fwd mac			*/
	O_LAST_OPCODE		/* not an opcode!		*/
};

/*
 * Template for instructions.
 *
 * ipfw_insn is used for all instructions which require no operands,
 * a single 16-bit value (arg1), or a couple of 8-bit values.
 *
 * For other instructions which require different/larger arguments
 * we have derived structures, ipfw_insn_*.
 *
 * The size of the instruction (in 32-bit words) is in the low
 * 6 bits of "len". The 2 remaining bits are used to implement
 * NOT and OR on individual instructions. Given a type, you can
 * compute the length to be put in "len" using F_INSN_SIZE(t)
 *
 * F_NOT	negates the match result of the instruction.
 *
 * F_OR		is used to build or blocks. By default, instructions
 *		are evaluated as part of a logical AND. An "or" block
 *		{ X or Y or Z } contains F_OR set in all but the last
 *		instruction of the block. A match will cause the code
 *		to skip past the last instruction of the block.
 *
 * NOTA BENE: in a couple of places we assume that
 *	sizeof(ipfw_insn) == sizeof(u_int32_t)
 * this needs to be fixed.
 *
 */
typedef struct	_ipfw_insn {	/* template for instructions */
	enum ipfw_opcodes	opcode:8;
	u_int8_t	len;	/* numer of 32-byte words */
#define	F_NOT		0x80
#define	F_OR		0x40
#define	F_LEN_MASK	0x3f
#define	F_LEN(cmd)	((cmd)->len & F_LEN_MASK)

	u_int16_t	arg1;
} ipfw_insn;

/*
 * The F_INSN_SIZE(type) computes the size, in 4-byte words, of
 * a given type.
 */
#define	F_INSN_SIZE(t)	((sizeof (t))/sizeof(u_int32_t))

/*
 * This is used to store an array of 16-bit entries (ports etc.)
 */
typedef struct	_ipfw_insn_u16 {
	ipfw_insn o;
	u_int16_t ports[2];	/* there may be more */
} ipfw_insn_u16;

/*
 * This is used to store an array of 32-bit entries
 * (uid, single IPv4 addresses etc.)
 */
typedef struct	_ipfw_insn_u32 {
	ipfw_insn o;
	u_int32_t d[1];	/* one or more */
} ipfw_insn_u32;

/*
 * This is used to store IP addr-mask pairs.
 */
typedef struct	_ipfw_insn_ip {
	ipfw_insn o;
	struct in_addr	addr;
	struct in_addr	mask;
} ipfw_insn_ip;

/*
 * This is used to forward to a given address (ip)
 */
typedef struct  _ipfw_insn_sa {
	ipfw_insn o;
	struct sockaddr_in sa;
} ipfw_insn_sa;

/*
 * This is used for MAC addr-mask pairs.
 */
typedef struct	_ipfw_insn_mac {
	ipfw_insn o;
	u_char addr[12];	/* dst[6] + src[6] */
	u_char mask[12];	/* dst[6] + src[6] */
} ipfw_insn_mac;

/*
 * This is used for interface match rules (recv xx, xmit xx)
 */
typedef struct	_ipfw_insn_if {
	ipfw_insn o;
	union {
		struct in_addr ip;
		int unit;
	} p;
	char name[IFNAMSIZ];
} ipfw_insn_if;

/*
 * This is used for pipe and queue actions, which need to store
 * a single pointer (which can have different size on different
 * architectures.
 */
typedef struct	_ipfw_insn_pipe {
	ipfw_insn	o;
	void		*pipe_ptr;
} ipfw_insn_pipe;

/*
 * This is used for limit rules.
 */
typedef struct	_ipfw_insn_limit {
	ipfw_insn o;
	u_int8_t _pad;
	u_int8_t limit_mask;	/* combination of DYN_* below	*/
#define	DYN_SRC_ADDR	0x1
#define	DYN_SRC_PORT	0x2
#define	DYN_DST_ADDR	0x4
#define	DYN_DST_PORT	0x8

	u_int16_t conn_limit;
} ipfw_insn_limit;

/*
 * This is used for log instructions
 */
typedef struct  _ipfw_insn_log {
        ipfw_insn o;
	u_int32_t max_log;	/* how many do we log -- 0 = all */
	u_int32_t log_left;	/* how many left to log 	*/
} ipfw_insn_log;

/*
 * Here we have the structure representing an ipfw rule.
 *
 * It starts with a general area (with link fields and counters)
 * followed by an array of one or more instructions, which the code
 * accesses as an array of 32-bit values.
 *
 * Given a rule pointer  r:
 *
 *  r->cmd		is the start of the first instruction.
 *  ACTION_PTR(r)	is the start of the first action (things to do
 *			once a rule matched).
 *
 * When assembling instruction, remember the following:
 *
 *  + if a rule has a "keep-state" (or "limit") option, then the
 *	first instruction (at r->cmd) MUST BE an O_PROBE_STATE
 *  + if a rule has a "log" option, then the first action
 *	(at ACTION_PTR(r)) MUST be O_LOG
 *
 * NOTE: we use a simple linked list of rules because we never need
 * 	to delete a rule without scanning the list. We do not use
 *	queue(3) macros for portability and readability.
 */

struct ip_fw {
	struct ip_fw	*next;		/* linked list of rules	*/
	u_int16_t	act_ofs;	/* offset of action in 32-bit units */
	u_int16_t	cmd_len;	/* # of 32-bit words in cmd	*/
	u_int16_t	rulenum;	/* rule number			*/
	u_int16_t	_pad;		/* padding			*/

	/* These fields are present in all rules.			*/
	u_int64_t	pcnt;		/* Packet counter		*/
	u_int64_t	bcnt;		/* Byte counter			*/
	u_int32_t	timestamp;	/* tv_sec of last match		*/

	struct ip_fw *next_rule;	/* ptr to next rule		*/

	ipfw_insn	cmd[1];		/* storage for commands		*/
};

#define ACTION_PTR(rule)				\
	(ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) )

#define RULESIZE(rule)  (sizeof(struct ip_fw) + \
	((struct ip_fw *)(rule))->cmd_len * 4 - 4)

/*
 * This structure is used as a flow mask and a flow id for various
 * parts of the code.
 */
struct ipfw_flow_id {
	u_int32_t	dst_ip;
	u_int32_t	src_ip;
	u_int16_t	dst_port;
	u_int16_t	src_port;
	u_int8_t	proto;
	u_int8_t	flags;	/* protocol-specific flags */
};

/*
 * dynamic ipfw rule
 */
typedef struct _ipfw_dyn_rule ipfw_dyn_rule;

struct _ipfw_dyn_rule {
	ipfw_dyn_rule	*next;		/* linked list of rules.	*/
	struct ipfw_flow_id id;		/* (masked) flow id		*/
	struct ip_fw *rule;		/* pointer to rule		*/
	ipfw_dyn_rule *parent;		/* pointer to parent rule	*/
	u_int32_t	expire;		/* expire time			*/
	u_int64_t	pcnt;		/* packet match counter		*/
	u_int64_t	bcnt;		/* byte match counter		*/
	u_int32_t	bucket;		/* which bucket in hash table	*/
	u_int32_t	state;		/* state of this rule (typically a
					 * combination of TCP flags)
					 */
	u_int16_t	dyn_type;	/* rule type			*/
	u_int16_t	count;		/* refcount			*/
};

/*
 * Definitions for IP option names.
 */
#define	IP_FW_IPOPT_LSRR	0x01
#define	IP_FW_IPOPT_SSRR	0x02
#define	IP_FW_IPOPT_RR		0x04
#define	IP_FW_IPOPT_TS		0x08

/*
 * Definitions for TCP option names.
 */
#define	IP_FW_TCPOPT_MSS	0x01
#define	IP_FW_TCPOPT_WINDOW	0x02
#define	IP_FW_TCPOPT_SACK	0x04
#define	IP_FW_TCPOPT_TS		0x08
#define	IP_FW_TCPOPT_CC		0x10

#define	ICMP_REJECT_RST		0x100	/* fake ICMP code (send a TCP RST) */

/*
 * Main firewall chains definitions and global var's definitions.
 */
#ifdef _KERNEL

#define	IP_FW_PORT_DYNT_FLAG	0x10000
#define	IP_FW_PORT_TEE_FLAG	0x20000
#define	IP_FW_PORT_DENY_FLAG	0x40000

/*
 * arguments for calling ipfw_chk() and dummynet_io(). We put them
 * all into a structure because this way it is easier and more
 * efficient to pass variables around and extend the interface.
 */
struct ip_fw_args {
	struct mbuf	*m;		/* the mbuf chain		*/
	struct ifnet	*oif;		/* output interface		*/
	struct sockaddr_in *next_hop;	/* forward address		*/
	struct ip_fw	*rule;		/* matching rule		*/
	struct ether_header *eh;	/* for bridged packets		*/

	struct route	*ro;		/* for dummynet			*/
	struct sockaddr_in *dst;	/* for dummynet			*/
	int flags;			/* for dummynet			*/

	struct ipfw_flow_id f_id;	/* grabbed from IP header	*/
	u_int16_t	divert_rule;	/* divert cookie		*/
	u_int32_t	retval;
};

/*
 * Function definitions.
 */

/* Firewall hooks */
struct sockopt;
struct dn_flow_set;

void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */

typedef int ip_fw_chk_t (struct ip_fw_args *args);
typedef int ip_fw_ctl_t (struct sockopt *);
extern ip_fw_chk_t *ip_fw_chk_ptr;
extern ip_fw_ctl_t *ip_fw_ctl_ptr;
extern int fw_one_pass;
extern int fw_enable;
#define	IPFW_LOADED	(ip_fw_chk_ptr != NULL)
#endif /* _KERNEL */

#endif /* _IPFW2_H */