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freebsd/sys/netinet/ip_fw.h
Luigi Rizzo 830cc17841 Two main changes here: 
+ implement "limit" rules, which permit to limit the number of sessions
   between certain host pairs (according to masks). These are a special
   type of stateful rules, which might be of interest in some cases.
   See the ipfw manpage for details.

 + merge the list pointers and ipfw rule descriptors in the kernel, so
   the code is smaller, faster and more readable. This patch basically
   consists in replacing "foo->rule->bar" with "rule->bar" all over
   the place.
   I have been willing to do this for ages!

MFC after: 1 week
2001-09-27 23:44:27 +00:00

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/*
* Copyright (c) 1993 Daniel Boulet
* Copyright (c) 1994 Ugen J.S.Antsilevich
*
* Redistribution and use in source forms, with and without modification,
* are permitted provided that this entire comment appears intact.
*
* Redistribution in binary form may occur without any restrictions.
* Obviously, it would be nice if you gave credit where credit is due
* but requiring it would be too onerous.
*
* This software is provided ``AS IS'' without any warranties of any kind.
*
* $FreeBSD$
*/
#ifndef _IP_FW_H
#define _IP_FW_H
#include <sys/queue.h>
/*
* This union structure identifies an interface, either explicitly
* by name or implicitly by IP address. The flags IP_FW_F_IIFNAME
* and IP_FW_F_OIFNAME say how to interpret this structure. An
* interface unit number of -1 matches any unit number, while an
* IP address of 0.0.0.0 indicates matches any interface.
*
* The receive and transmit interfaces are only compared against the
* the packet if the corresponding bit (IP_FW_F_IIFACE or IP_FW_F_OIFACE)
* is set. Note some packets lack a receive or transmit interface
* (in which case the missing "interface" never matches).
*/
union ip_fw_if {
struct in_addr fu_via_ip; /* Specified by IP address */
struct { /* Specified by interface name */
#define FW_IFNLEN 10 /* need room ! was IFNAMSIZ */
char name[FW_IFNLEN];
short unit; /* -1 means match any unit */
} fu_via_if;
};
/*
* Format of an IP firewall descriptor
*
* fw_src, fw_dst, fw_smsk, fw_dmsk are always stored in network byte order.
* fw_flg and fw_n*p are stored in host byte order (of course).
* Port numbers are stored in HOST byte order.
*/
struct ip_fw {
LIST_ENTRY(ip_fw) next; /* bidirectional list of rules */
u_int fw_flg; /* Operational Flags word */
u_int64_t fw_pcnt,fw_bcnt; /* Packet and byte counters */
struct in_addr fw_src, fw_dst; /* Source and dest. IP addr */
struct in_addr fw_smsk, fw_dmsk; /* Mask for above addresses */
u_short fw_number; /* Rule number */
u_char fw_prot; /* IP protocol */
#if 1
u_char fw_nports; /* # of src/dst port in array */
#define IP_FW_GETNSRCP(rule) ((rule)->fw_nports & 0x0f)
#define IP_FW_SETNSRCP(rule, n) do { \
(rule)->fw_nports &= ~0x0f; \
(rule)->fw_nports |= (n); \
} while (0)
#define IP_FW_GETNDSTP(rule) ((rule)->fw_nports >> 4)
#define IP_FW_SETNDSTP(rule, n) do { \
(rule)->fw_nports &= ~0xf0; \
(rule)->fw_nports |= (n) << 4;\
} while (0)
#define IP_FW_HAVEPORTS(rule) ((rule)->fw_nports != 0)
#else
u_char __pad[1];
u_int _nsrcp, _ndstp;
#define IP_FW_GETNSRCP(rule) (rule)->_nsrcp
#define IP_FW_SETNSRCP(rule,n) (rule)->_nsrcp = n
#define IP_FW_GETNDSTP(rule) (rule)->_ndstp
#define IP_FW_SETNDSTP(rule,n) (rule)->_ndstp = n
#define IP_FW_HAVEPORTS(rule) ((rule)->_ndstp + (rule)->_nsrcp != 0)
#endif
#define IP_FW_MAX_PORTS 10 /* A reasonable maximum */
union {
u_short fw_pts[IP_FW_MAX_PORTS]; /* port numbers to match */
#define IP_FW_ICMPTYPES_MAX 128
#define IP_FW_ICMPTYPES_DIM (IP_FW_ICMPTYPES_MAX / (sizeof(unsigned) * 8))
unsigned fw_icmptypes[IP_FW_ICMPTYPES_DIM]; /* ICMP types bitmap */
} fw_uar;
u_int fw_ipflg; /* IP flags word */
u_short fw_iplen, fw_ipid; /* IP length, identification */
u_char fw_ipopt,fw_ipnopt; /* IP options set/unset */
u_char fw_iptos, fw_ipntos; /* IP type of service set/unset */
u_char fw_ipttl; /* IP time to live */
u_int fw_ipver:4; /* IP version */
u_char fw_tcpopt,fw_tcpnopt; /* TCP options set/unset */
u_char fw_tcpf,fw_tcpnf; /* TCP flags set/unset */
u_short fw_tcpwin; /* TCP window size */
u_int32_t fw_tcpseq, fw_tcpack; /* TCP sequence and acknowledgement */
long timestamp; /* timestamp (tv_sec) of last match */
union ip_fw_if fw_in_if, fw_out_if; /* Incoming and outgoing interfaces */
union {
u_short fu_divert_port; /* Divert/tee port (options IPDIVERT) */
u_short fu_pipe_nr; /* queue number (option DUMMYNET) */
u_short fu_skipto_rule; /* SKIPTO command rule number */
u_short fu_reject_code; /* REJECT response code */
struct sockaddr_in fu_fwd_ip;
} fw_un;
void *pipe_ptr; /* flow_set ptr for dummynet pipe */
void *next_rule_ptr ; /* next rule in case of match */
uid_t fw_uid; /* uid to match */
gid_t fw_gid; /* gid to match */
int fw_logamount; /* amount to log */
u_int64_t fw_loghighest; /* highest number packet to log */
long dont_match_prob; /* 0x7fffffff means 1.0, always fail */
u_char dyn_type; /* type for dynamic rule */
#define DYN_KEEP_STATE 0 /* type for keep-state rules */
#define DYN_LIMIT 1 /* type for limit connection rules */
#define DYN_LIMIT_PARENT 2 /* parent entry for limit connection rules */
/* following two fields are used to limit number of connections
* basing on either src,srcport,dst,dstport.
*/
u_char limit_mask ; /* mask type for limit rule, can have many */
#define DYN_SRC_ADDR 0x1
#define DYN_SRC_PORT 0x2
#define DYN_DST_ADDR 0x4
#define DYN_DST_PORT 0x8
u_short conn_limit ; /* # of connections for limit rule */
};
#define fw_divert_port fw_un.fu_divert_port
#define fw_skipto_rule fw_un.fu_skipto_rule
#define fw_reject_code fw_un.fu_reject_code
#define fw_pipe_nr fw_un.fu_pipe_nr
#define fw_fwd_ip fw_un.fu_fwd_ip
/**
*
* rule_ptr -------------+
* V
* [ next.le_next ]---->[ next.le_next ]---- [ next.le_next ]--->
* [ next.le_prev ]<----[ next.le_prev ]<----[ next.le_prev ]<---
* [ <ip_fw> body ] [ <ip_fw> body ] [ <ip_fw> body ]
*
*/
/*
* Flow mask/flow id for each queue.
*/
struct ipfw_flow_id {
u_int32_t dst_ip, src_ip ;
u_int16_t dst_port, src_port ;
u_int8_t proto ;
u_int8_t flags ; /* protocol-specific flags */
} ;
/*
* dynamic ipfw rule
*/
struct ipfw_dyn_rule {
struct ipfw_dyn_rule *next ;
struct ipfw_flow_id id ; /* (masked) flow id */
struct ip_fw *rule ; /* pointer to rule */
struct ipfw_dyn_rule *parent ; /* pointer to parent rule */
u_int32_t expire ; /* expire time */
u_int64_t pcnt, bcnt; /* match counters */
u_int32_t bucket ; /* which bucket in hash table */
u_int32_t state ; /* state of this rule (typ. a */
/* combination of TCP flags) */
u_int16_t dyn_type; /* rule type */
u_int16_t count; /* refcount */
} ;
/*
* Values for "flags" field .
*/
#define IP_FW_F_COMMAND 0x000000ff /* Mask for type of chain entry: */
#define IP_FW_F_DENY 0x00000000 /* This is a deny rule */
#define IP_FW_F_REJECT 0x00000001 /* Deny and send a response packet */
#define IP_FW_F_ACCEPT 0x00000002 /* This is an accept rule */
#define IP_FW_F_COUNT 0x00000003 /* This is a count rule */
#define IP_FW_F_DIVERT 0x00000004 /* This is a divert rule */
#define IP_FW_F_TEE 0x00000005 /* This is a tee rule */
#define IP_FW_F_SKIPTO 0x00000006 /* This is a skipto rule */
#define IP_FW_F_FWD 0x00000007 /* This is a "change forwarding address" rule */
#define IP_FW_F_PIPE 0x00000008 /* This is a dummynet rule */
#define IP_FW_F_QUEUE 0x00000009 /* This is a dummynet queue */
#define IP_FW_F_IN 0x00000100 /* Check inbound packets */
#define IP_FW_F_OUT 0x00000200 /* Check outbound packets */
#define IP_FW_F_IIFACE 0x00000400 /* Apply inbound interface test */
#define IP_FW_F_OIFACE 0x00000800 /* Apply outbound interface test */
#define IP_FW_F_PRN 0x00001000 /* Print if this rule matches */
#define IP_FW_F_SRNG 0x00002000 /* The first two src ports are a min *
* and max range (stored in host byte *
* order). */
#define IP_FW_F_DRNG 0x00004000 /* The first two dst ports are a min *
* and max range (stored in host byte *
* order). */
#define IP_FW_F_FRAG 0x00008000 /* Fragment */
#define IP_FW_F_IIFNAME 0x00010000 /* In interface by name/unit (not IP) */
#define IP_FW_F_OIFNAME 0x00020000 /* Out interface by name/unit (not IP) */
#define IP_FW_F_INVSRC 0x00040000 /* Invert sense of src check */
#define IP_FW_F_INVDST 0x00080000 /* Invert sense of dst check */
#define IP_FW_F_ICMPBIT 0x00100000 /* ICMP type bitmap is valid */
#define IP_FW_F_UID 0x00200000 /* filter by uid */
#define IP_FW_F_GID 0x00400000 /* filter by gid */
#define IP_FW_F_RND_MATCH 0x00800000 /* probabilistic rule match */
#define IP_FW_F_SMSK 0x01000000 /* src-port + mask */
#define IP_FW_F_DMSK 0x02000000 /* dst-port + mask */
#define IP_FW_BRIDGED 0x04000000 /* only match bridged packets */
#define IP_FW_F_KEEP_S 0x08000000 /* keep state */
#define IP_FW_F_CHECK_S 0x10000000 /* check state */
#define IP_FW_F_SME 0x20000000 /* source = me */
#define IP_FW_F_DME 0x40000000 /* destination = me */
#define IP_FW_F_MASK 0x7FFFFFFF /* All possible flag bits mask */
/*
* Flags for the 'fw_ipflg' field, for comparing values of ip and its protocols.
*/
#define IP_FW_IF_TCPOPT 0x00000001 /* tcp options */
#define IP_FW_IF_TCPFLG 0x00000002 /* tcp flags */
#define IP_FW_IF_TCPSEQ 0x00000004 /* tcp sequence number */
#define IP_FW_IF_TCPACK 0x00000008 /* tcp acknowledgement number */
#define IP_FW_IF_TCPWIN 0x00000010 /* tcp window size */
#define IP_FW_IF_TCPEST 0x00000020 /* established TCP connection */
#define IP_FW_IF_TCPMSK 0x0000003f /* mask of all tcp values */
#define IP_FW_IF_IPOPT 0x00000100 /* ip options */
#define IP_FW_IF_IPLEN 0x00000200 /* ip length */
#define IP_FW_IF_IPID 0x00000400 /* ip identification */
#define IP_FW_IF_IPTOS 0x00000800 /* ip type of service */
#define IP_FW_IF_IPTTL 0x00001000 /* ip time to live */
#define IP_FW_IF_IPVER 0x00002000 /* ip version */
#define IP_FW_IF_IPMSK 0x00003f00 /* mask of all ip values */
#define IP_FW_IF_MSK 0x0000ffff /* All possible bits mask */
/*
* For backwards compatibility with rules specifying "via iface" but
* not restricted to only "in" or "out" packets, we define this combination
* of bits to represent this configuration.
*/
#define IF_FW_F_VIAHACK (IP_FW_F_IN|IP_FW_F_OUT|IP_FW_F_IIFACE|IP_FW_F_OIFACE)
/*
* Definitions for REJECT response codes.
* Values less than 256 correspond to ICMP unreachable codes.
*/
#define IP_FW_REJECT_RST 0x0100 /* TCP packets: send RST */
/*
* 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
/*
* Definitions for TCP flags.
*/
#define IP_FW_TCPF_FIN TH_FIN
#define IP_FW_TCPF_SYN TH_SYN
#define IP_FW_TCPF_RST TH_RST
#define IP_FW_TCPF_PSH TH_PUSH
#define IP_FW_TCPF_ACK TH_ACK
#define IP_FW_TCPF_URG TH_URG
/*
* 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
/*
* Function definitions.
*/
void ip_fw_init __P((void));
/* Firewall hooks */
struct ip;
struct sockopt;
typedef int ip_fw_chk_t (struct ip **, int, struct ifnet *, u_int16_t *,
struct mbuf **, struct ip_fw **, struct sockaddr_in **);
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;
extern struct ipfw_flow_id last_pkt ;
#endif /* _KERNEL */
#endif /* _IP_FW_H */
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