The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_fw.h

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    1 /*-
    2  * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. Redistributions in binary form must reproduce the above copyright
   10  *    notice, this list of conditions and the following disclaimer in the
   11  *    documentation and/or other materials provided with the distribution.
   12  *
   13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   23  * SUCH DAMAGE.
   24  *
   25  * $FreeBSD: releng/5.4/sys/netinet/ip_fw.h 145335 2005-04-20 19:11:07Z cvs2svn $
   26  */
   27 
   28 #ifndef _IPFW2_H
   29 #define _IPFW2_H
   30 #define IPFW2  1
   31 
   32 /*
   33  * The kernel representation of ipfw rules is made of a list of
   34  * 'instructions' (for all practical purposes equivalent to BPF
   35  * instructions), which specify which fields of the packet
   36  * (or its metadata) should be analysed.
   37  *
   38  * Each instruction is stored in a structure which begins with
   39  * "ipfw_insn", and can contain extra fields depending on the
   40  * instruction type (listed below).
   41  * Note that the code is written so that individual instructions
   42  * have a size which is a multiple of 32 bits. This means that, if
   43  * such structures contain pointers or other 64-bit entities,
   44  * (there is just one instance now) they may end up unaligned on
   45  * 64-bit architectures, so the must be handled with care.
   46  *
   47  * "enum ipfw_opcodes" are the opcodes supported. We can have up
   48  * to 256 different opcodes. When adding new opcodes, they should
   49  * be appended to the end of the opcode list before O_LAST_OPCODE,
   50  * this will prevent the ABI from being broken, otherwise users
   51  * will have to recompile ipfw(8) when they update the kernel.
   52  */
   53 
   54 enum ipfw_opcodes {             /* arguments (4 byte each)      */
   55         O_NOP,
   56 
   57         O_IP_SRC,               /* u32 = IP                     */
   58         O_IP_SRC_MASK,          /* ip = IP/mask                 */
   59         O_IP_SRC_ME,            /* none                         */
   60         O_IP_SRC_SET,           /* u32=base, arg1=len, bitmap   */
   61 
   62         O_IP_DST,               /* u32 = IP                     */
   63         O_IP_DST_MASK,          /* ip = IP/mask                 */
   64         O_IP_DST_ME,            /* none                         */
   65         O_IP_DST_SET,           /* u32=base, arg1=len, bitmap   */
   66 
   67         O_IP_SRCPORT,           /* (n)port list:mask 4 byte ea  */
   68         O_IP_DSTPORT,           /* (n)port list:mask 4 byte ea  */
   69         O_PROTO,                /* arg1=protocol                */
   70 
   71         O_MACADDR2,             /* 2 mac addr:mask              */
   72         O_MAC_TYPE,             /* same as srcport              */
   73 
   74         O_LAYER2,               /* none                         */
   75         O_IN,                   /* none                         */
   76         O_FRAG,                 /* none                         */
   77 
   78         O_RECV,                 /* none                         */
   79         O_XMIT,                 /* none                         */
   80         O_VIA,                  /* none                         */
   81 
   82         O_IPOPT,                /* arg1 = 2*u8 bitmap           */
   83         O_IPLEN,                /* arg1 = len                   */
   84         O_IPID,                 /* arg1 = id                    */
   85 
   86         O_IPTOS,                /* arg1 = id                    */
   87         O_IPPRECEDENCE,         /* arg1 = precedence << 5       */
   88         O_IPTTL,                /* arg1 = TTL                   */
   89 
   90         O_IPVER,                /* arg1 = version               */
   91         O_UID,                  /* u32 = id                     */
   92         O_GID,                  /* u32 = id                     */
   93         O_ESTAB,                /* none (tcp established)       */
   94         O_TCPFLAGS,             /* arg1 = 2*u8 bitmap           */
   95         O_TCPWIN,               /* arg1 = desired win           */
   96         O_TCPSEQ,               /* u32 = desired seq.           */
   97         O_TCPACK,               /* u32 = desired seq.           */
   98         O_ICMPTYPE,             /* u32 = icmp bitmap            */
   99         O_TCPOPTS,              /* arg1 = 2*u8 bitmap           */
  100 
  101         O_VERREVPATH,           /* none                         */
  102         O_VERSRCREACH,          /* none                         */
  103 
  104         O_PROBE_STATE,          /* none                         */
  105         O_KEEP_STATE,           /* none                         */
  106         O_LIMIT,                /* ipfw_insn_limit              */
  107         O_LIMIT_PARENT,         /* dyn_type, not an opcode.     */
  108 
  109         /*
  110          * These are really 'actions'.
  111          */
  112 
  113         O_LOG,                  /* ipfw_insn_log                */
  114         O_PROB,                 /* u32 = match probability      */
  115 
  116         O_CHECK_STATE,          /* none                         */
  117         O_ACCEPT,               /* none                         */
  118         O_DENY,                 /* none                         */
  119         O_REJECT,               /* arg1=icmp arg (same as deny) */
  120         O_COUNT,                /* none                         */
  121         O_SKIPTO,               /* arg1=next rule number        */
  122         O_PIPE,                 /* arg1=pipe number             */
  123         O_QUEUE,                /* arg1=queue number            */
  124         O_DIVERT,               /* arg1=port number             */
  125         O_TEE,                  /* arg1=port number             */
  126         O_FORWARD_IP,           /* fwd sockaddr                 */
  127         O_FORWARD_MAC,          /* fwd mac                      */
  128 
  129         /*
  130          * More opcodes.
  131          */
  132         O_IPSEC,                /* has ipsec history            */
  133         O_IP_SRC_LOOKUP,        /* arg1=table number, u32=value */
  134         O_IP_DST_LOOKUP,        /* arg1=table number, u32=value */
  135         O_ANTISPOOF,            /* none                         */
  136         O_JAIL,                 /* u32 = id                     */
  137 
  138         O_LAST_OPCODE           /* not an opcode!               */
  139 };
  140 
  141 /*
  142  * Template for instructions.
  143  *
  144  * ipfw_insn is used for all instructions which require no operands,
  145  * a single 16-bit value (arg1), or a couple of 8-bit values.
  146  *
  147  * For other instructions which require different/larger arguments
  148  * we have derived structures, ipfw_insn_*.
  149  *
  150  * The size of the instruction (in 32-bit words) is in the low
  151  * 6 bits of "len". The 2 remaining bits are used to implement
  152  * NOT and OR on individual instructions. Given a type, you can
  153  * compute the length to be put in "len" using F_INSN_SIZE(t)
  154  *
  155  * F_NOT        negates the match result of the instruction.
  156  *
  157  * F_OR         is used to build or blocks. By default, instructions
  158  *              are evaluated as part of a logical AND. An "or" block
  159  *              { X or Y or Z } contains F_OR set in all but the last
  160  *              instruction of the block. A match will cause the code
  161  *              to skip past the last instruction of the block.
  162  *
  163  * NOTA BENE: in a couple of places we assume that
  164  *      sizeof(ipfw_insn) == sizeof(u_int32_t)
  165  * this needs to be fixed.
  166  *
  167  */
  168 typedef struct  _ipfw_insn {    /* template for instructions */
  169         enum ipfw_opcodes       opcode:8;
  170         u_int8_t        len;    /* numer of 32-byte words */
  171 #define F_NOT           0x80
  172 #define F_OR            0x40
  173 #define F_LEN_MASK      0x3f
  174 #define F_LEN(cmd)      ((cmd)->len & F_LEN_MASK)
  175 
  176         u_int16_t       arg1;
  177 } ipfw_insn;
  178 
  179 /*
  180  * The F_INSN_SIZE(type) computes the size, in 4-byte words, of
  181  * a given type.
  182  */
  183 #define F_INSN_SIZE(t)  ((sizeof (t))/sizeof(u_int32_t))
  184 
  185 /*
  186  * This is used to store an array of 16-bit entries (ports etc.)
  187  */
  188 typedef struct  _ipfw_insn_u16 {
  189         ipfw_insn o;
  190         u_int16_t ports[2];     /* there may be more */
  191 } ipfw_insn_u16;
  192 
  193 /*
  194  * This is used to store an array of 32-bit entries
  195  * (uid, single IPv4 addresses etc.)
  196  */
  197 typedef struct  _ipfw_insn_u32 {
  198         ipfw_insn o;
  199         u_int32_t d[1]; /* one or more */
  200 } ipfw_insn_u32;
  201 
  202 /*
  203  * This is used to store IP addr-mask pairs.
  204  */
  205 typedef struct  _ipfw_insn_ip {
  206         ipfw_insn o;
  207         struct in_addr  addr;
  208         struct in_addr  mask;
  209 } ipfw_insn_ip;
  210 
  211 /*
  212  * This is used to forward to a given address (ip).
  213  */
  214 typedef struct  _ipfw_insn_sa {
  215         ipfw_insn o;
  216         struct sockaddr_in sa;
  217 } ipfw_insn_sa;
  218 
  219 /*
  220  * This is used for MAC addr-mask pairs.
  221  */
  222 typedef struct  _ipfw_insn_mac {
  223         ipfw_insn o;
  224         u_char addr[12];        /* dst[6] + src[6] */
  225         u_char mask[12];        /* dst[6] + src[6] */
  226 } ipfw_insn_mac;
  227 
  228 /*
  229  * This is used for interface match rules (recv xx, xmit xx).
  230  */
  231 typedef struct  _ipfw_insn_if {
  232         ipfw_insn o;
  233         union {
  234                 struct in_addr ip;
  235                 int glob;
  236         } p;
  237         char name[IFNAMSIZ];
  238 } ipfw_insn_if;
  239 
  240 /*
  241  * This is used for pipe and queue actions, which need to store
  242  * a single pointer (which can have different size on different
  243  * architectures.
  244  * Note that, because of previous instructions, pipe_ptr might
  245  * be unaligned in the overall structure, so it needs to be
  246  * manipulated with care.
  247  */
  248 typedef struct  _ipfw_insn_pipe {
  249         ipfw_insn       o;
  250         void            *pipe_ptr;      /* XXX */
  251 } ipfw_insn_pipe;
  252 
  253 /*
  254  * This is used for limit rules.
  255  */
  256 typedef struct  _ipfw_insn_limit {
  257         ipfw_insn o;
  258         u_int8_t _pad;
  259         u_int8_t limit_mask;    /* combination of DYN_* below   */
  260 #define DYN_SRC_ADDR    0x1
  261 #define DYN_SRC_PORT    0x2
  262 #define DYN_DST_ADDR    0x4
  263 #define DYN_DST_PORT    0x8
  264 
  265         u_int16_t conn_limit;
  266 } ipfw_insn_limit;
  267 
  268 /*
  269  * This is used for log instructions.
  270  */
  271 typedef struct  _ipfw_insn_log {
  272         ipfw_insn o;
  273         u_int32_t max_log;      /* how many do we log -- 0 = all */
  274         u_int32_t log_left;     /* how many left to log         */
  275 } ipfw_insn_log;
  276 
  277 /*
  278  * Here we have the structure representing an ipfw rule.
  279  *
  280  * It starts with a general area (with link fields and counters)
  281  * followed by an array of one or more instructions, which the code
  282  * accesses as an array of 32-bit values.
  283  *
  284  * Given a rule pointer  r:
  285  *
  286  *  r->cmd              is the start of the first instruction.
  287  *  ACTION_PTR(r)       is the start of the first action (things to do
  288  *                      once a rule matched).
  289  *
  290  * When assembling instruction, remember the following:
  291  *
  292  *  + if a rule has a "keep-state" (or "limit") option, then the
  293  *      first instruction (at r->cmd) MUST BE an O_PROBE_STATE
  294  *  + if a rule has a "log" option, then the first action
  295  *      (at ACTION_PTR(r)) MUST be O_LOG
  296  *
  297  * NOTE: we use a simple linked list of rules because we never need
  298  *      to delete a rule without scanning the list. We do not use
  299  *      queue(3) macros for portability and readability.
  300  */
  301 
  302 struct ip_fw {
  303         struct ip_fw    *next;          /* linked list of rules         */
  304         struct ip_fw    *next_rule;     /* ptr to next [skipto] rule    */
  305         /* 'next_rule' is used to pass up 'set_disable' status          */
  306 
  307         u_int16_t       act_ofs;        /* offset of action in 32-bit units */
  308         u_int16_t       cmd_len;        /* # of 32-bit words in cmd     */
  309         u_int16_t       rulenum;        /* rule number                  */
  310         u_int8_t        set;            /* rule set (0..31)             */
  311 #define RESVD_SET       31      /* set for default and persistent rules */
  312         u_int8_t        _pad;           /* padding                      */
  313 
  314         /* These fields are present in all rules.                       */
  315         u_int64_t       pcnt;           /* Packet counter               */
  316         u_int64_t       bcnt;           /* Byte counter                 */
  317         u_int32_t       timestamp;      /* tv_sec of last match         */
  318 
  319         ipfw_insn       cmd[1];         /* storage for commands         */
  320 };
  321 
  322 #define ACTION_PTR(rule)                                \
  323         (ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) )
  324 
  325 #define RULESIZE(rule)  (sizeof(struct ip_fw) + \
  326         ((struct ip_fw *)(rule))->cmd_len * 4 - 4)
  327 
  328 /*
  329  * This structure is used as a flow mask and a flow id for various
  330  * parts of the code.
  331  */
  332 struct ipfw_flow_id {
  333         u_int32_t       dst_ip;
  334         u_int32_t       src_ip;
  335         u_int16_t       dst_port;
  336         u_int16_t       src_port;
  337         u_int8_t        proto;
  338         u_int8_t        flags;  /* protocol-specific flags */
  339 };
  340 
  341 /*
  342  * Dynamic ipfw rule.
  343  */
  344 typedef struct _ipfw_dyn_rule ipfw_dyn_rule;
  345 
  346 struct _ipfw_dyn_rule {
  347         ipfw_dyn_rule   *next;          /* linked list of rules.        */
  348         struct ip_fw *rule;             /* pointer to rule              */
  349         /* 'rule' is used to pass up the rule number (from the parent)  */
  350 
  351         ipfw_dyn_rule *parent;          /* pointer to parent rule       */
  352         u_int64_t       pcnt;           /* packet match counter         */
  353         u_int64_t       bcnt;           /* byte match counter           */
  354         struct ipfw_flow_id id;         /* (masked) flow id             */
  355         u_int32_t       expire;         /* expire time                  */
  356         u_int32_t       bucket;         /* which bucket in hash table   */
  357         u_int32_t       state;          /* state of this rule (typically a
  358                                          * combination of TCP flags)
  359                                          */
  360         u_int32_t       ack_fwd;        /* most recent ACKs in forward  */
  361         u_int32_t       ack_rev;        /* and reverse directions (used */
  362                                         /* to generate keepalives)      */
  363         u_int16_t       dyn_type;       /* rule type                    */
  364         u_int16_t       count;          /* refcount                     */
  365 };
  366 
  367 /*
  368  * Definitions for IP option names.
  369  */
  370 #define IP_FW_IPOPT_LSRR        0x01
  371 #define IP_FW_IPOPT_SSRR        0x02
  372 #define IP_FW_IPOPT_RR          0x04
  373 #define IP_FW_IPOPT_TS          0x08
  374 
  375 /*
  376  * Definitions for TCP option names.
  377  */
  378 #define IP_FW_TCPOPT_MSS        0x01
  379 #define IP_FW_TCPOPT_WINDOW     0x02
  380 #define IP_FW_TCPOPT_SACK       0x04
  381 #define IP_FW_TCPOPT_TS         0x08
  382 #define IP_FW_TCPOPT_CC         0x10
  383 
  384 #define ICMP_REJECT_RST         0x100   /* fake ICMP code (send a TCP RST) */
  385 
  386 /*
  387  * These are used for lookup tables.
  388  */
  389 typedef struct  _ipfw_table_entry {
  390         in_addr_t       addr;           /* network address              */
  391         u_int32_t       value;          /* value                        */
  392         u_int16_t       tbl;            /* table number                 */
  393         u_int8_t        masklen;        /* mask length                  */
  394 } ipfw_table_entry;
  395 
  396 typedef struct  _ipfw_table {
  397         u_int32_t       size;           /* size of entries in bytes     */
  398         u_int32_t       cnt;            /* # of entries                 */
  399         u_int16_t       tbl;            /* table number                 */
  400         ipfw_table_entry ent[0];        /* entries                      */
  401 } ipfw_table;
  402 
  403 /*
  404  * Main firewall chains definitions and global var's definitions.
  405  */
  406 #ifdef _KERNEL
  407 
  408 #define IP_FW_PORT_DYNT_FLAG    0x10000
  409 #define IP_FW_PORT_TEE_FLAG     0x20000
  410 #define IP_FW_PORT_DENY_FLAG    0x40000
  411 
  412 /*
  413  * Arguments for calling ipfw_chk() and dummynet_io(). We put them
  414  * all into a structure because this way it is easier and more
  415  * efficient to pass variables around and extend the interface.
  416  */
  417 struct ip_fw_args {
  418         struct mbuf     *m;             /* the mbuf chain               */
  419         struct ifnet    *oif;           /* output interface             */
  420         struct sockaddr_in *next_hop;   /* forward address              */
  421         struct ip_fw    *rule;          /* matching rule                */
  422         struct ether_header *eh;        /* for bridged packets          */
  423 
  424         int flags;                      /* for dummynet                 */
  425 
  426         struct ipfw_flow_id f_id;       /* grabbed from IP header       */
  427         u_int32_t       retval;
  428         struct inpcb    *inp;
  429 };
  430 
  431 /*
  432  * Function definitions.
  433  */
  434 
  435 /* Firewall hooks */
  436 struct sockopt;
  437 struct dn_flow_set;
  438 
  439 int ipfw_check_in(void *, struct mbuf **, struct ifnet *, int, struct inpcb *inp);
  440 int ipfw_check_out(void *, struct mbuf **, struct ifnet *, int, struct inpcb *inp);
  441 
  442 int ipfw_chk(struct ip_fw_args *);
  443 
  444 int ipfw_init(void);
  445 void ipfw_destroy(void);
  446 
  447 void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */
  448 
  449 typedef int ip_fw_ctl_t(struct sockopt *);
  450 extern ip_fw_ctl_t *ip_fw_ctl_ptr;
  451 extern int fw_one_pass;
  452 extern int fw_enable;
  453 
  454 /* For kernel ipfw_ether and ipfw_bridge. */
  455 typedef int ip_fw_chk_t(struct ip_fw_args *args);
  456 extern  ip_fw_chk_t     *ip_fw_chk_ptr;
  457 #define IPFW_LOADED     (ip_fw_chk_ptr != NULL)
  458 
  459 #endif /* _KERNEL */
  460 #endif /* _IPFW2_H */

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