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/5.0/sys/netinet/ip_fw.h 105899 2002-10-24 22:32:13Z mux $
   26  */
   27 
   28 #ifndef _IPFW2_H
   29 #define _IPFW2_H
   30 #define IPFW2  1
   31 /*
   32  * The kernel representation of ipfw rules is made of a list of
   33  * 'instructions' (for all practical purposes equivalent to BPF
   34  * instructions), which specify which fields of the packet
   35  * (or its metatada) should be analysed.
   36  *
   37  * Each instruction is stored in a structure which begins with
   38  * "ipfw_insn", and can contain extra fields depending on the
   39  * instruction type (listed below).
   40  *
   41  * "enum ipfw_opcodes" are the opcodes supported. We can have up
   42  * to 256 different opcodes.
   43  */
   44 
   45 enum ipfw_opcodes {             /* arguments (4 byte each)      */
   46         O_NOP,
   47 
   48         O_IP_SRC,               /* u32 = IP                     */
   49         O_IP_SRC_MASK,          /* ip = IP/mask                 */
   50         O_IP_SRC_ME,            /* none                         */
   51         O_IP_SRC_SET,           /* u32=base, arg1=len, bitmap   */
   52 
   53         O_IP_DST,               /* u32 = IP                     */
   54         O_IP_DST_MASK,          /* ip = IP/mask                 */
   55         O_IP_DST_ME,            /* none                         */
   56         O_IP_DST_SET,           /* u32=base, arg1=len, bitmap   */
   57 
   58         O_IP_SRCPORT,           /* (n)port list:mask 4 byte ea  */
   59         O_IP_DSTPORT,           /* (n)port list:mask 4 byte ea  */
   60         O_PROTO,                /* arg1=protocol                */
   61 
   62         O_MACADDR2,             /* 2 mac addr:mask              */
   63         O_MAC_TYPE,             /* same as srcport              */
   64 
   65         O_LAYER2,               /* none                         */
   66         O_IN,                   /* none                         */
   67         O_FRAG,                 /* none                         */
   68 
   69         O_RECV,                 /* none                         */
   70         O_XMIT,                 /* none                         */
   71         O_VIA,                  /* none                         */
   72 
   73         O_IPOPT,                /* arg1 = 2*u8 bitmap           */
   74         O_IPLEN,                /* arg1 = len                   */
   75         O_IPID,                 /* arg1 = id                    */
   76 
   77         O_IPTOS,                /* arg1 = id                    */
   78         O_IPPRECEDENCE,         /* arg1 = precedence << 5       */
   79         O_IPTTL,                /* arg1 = TTL                   */
   80 
   81         O_IPVER,                /* arg1 = version               */
   82         O_UID,                  /* u32 = id                     */
   83         O_GID,                  /* u32 = id                     */
   84         O_ESTAB,                /* none (tcp established)       */
   85         O_TCPFLAGS,             /* arg1 = 2*u8 bitmap           */
   86         O_TCPWIN,               /* arg1 = desired win           */
   87         O_TCPSEQ,               /* u32 = desired seq.           */
   88         O_TCPACK,               /* u32 = desired seq.           */
   89         O_ICMPTYPE,             /* u32 = icmp bitmap            */
   90         O_TCPOPTS,              /* arg1 = 2*u8 bitmap           */
   91 
   92         O_PROBE_STATE,          /* none                         */
   93         O_KEEP_STATE,           /* none                         */
   94         O_LIMIT,                /* ipfw_insn_limit              */
   95         O_LIMIT_PARENT,         /* dyn_type, not an opcode.     */
   96         /*
   97          * these are really 'actions', and must be last in the list.
   98          */
   99 
  100         O_LOG,                  /* ipfw_insn_log                */
  101         O_PROB,                 /* u32 = match probability      */
  102 
  103         O_CHECK_STATE,          /* none                         */
  104         O_ACCEPT,               /* none                         */
  105         O_DENY,                 /* none                         */
  106         O_REJECT,               /* arg1=icmp arg (same as deny) */
  107         O_COUNT,                /* none                         */
  108         O_SKIPTO,               /* arg1=next rule number        */
  109         O_PIPE,                 /* arg1=pipe number             */
  110         O_QUEUE,                /* arg1=queue number            */
  111         O_DIVERT,               /* arg1=port number             */
  112         O_TEE,                  /* arg1=port number             */
  113         O_FORWARD_IP,           /* fwd sockaddr                 */
  114         O_FORWARD_MAC,          /* fwd mac                      */
  115         O_LAST_OPCODE           /* not an opcode!               */
  116 };
  117 
  118 /*
  119  * Template for instructions.
  120  *
  121  * ipfw_insn is used for all instructions which require no operands,
  122  * a single 16-bit value (arg1), or a couple of 8-bit values.
  123  *
  124  * For other instructions which require different/larger arguments
  125  * we have derived structures, ipfw_insn_*.
  126  *
  127  * The size of the instruction (in 32-bit words) is in the low
  128  * 6 bits of "len". The 2 remaining bits are used to implement
  129  * NOT and OR on individual instructions. Given a type, you can
  130  * compute the length to be put in "len" using F_INSN_SIZE(t)
  131  *
  132  * F_NOT        negates the match result of the instruction.
  133  *
  134  * F_OR         is used to build or blocks. By default, instructions
  135  *              are evaluated as part of a logical AND. An "or" block
  136  *              { X or Y or Z } contains F_OR set in all but the last
  137  *              instruction of the block. A match will cause the code
  138  *              to skip past the last instruction of the block.
  139  *
  140  * NOTA BENE: in a couple of places we assume that
  141  *      sizeof(ipfw_insn) == sizeof(u_int32_t)
  142  * this needs to be fixed.
  143  *
  144  */
  145 typedef struct  _ipfw_insn {    /* template for instructions */
  146         enum ipfw_opcodes       opcode:8;
  147         u_int8_t        len;    /* numer of 32-byte words */
  148 #define F_NOT           0x80
  149 #define F_OR            0x40
  150 #define F_LEN_MASK      0x3f
  151 #define F_LEN(cmd)      ((cmd)->len & F_LEN_MASK)
  152 
  153         u_int16_t       arg1;
  154 } ipfw_insn;
  155 
  156 /*
  157  * The F_INSN_SIZE(type) computes the size, in 4-byte words, of
  158  * a given type.
  159  */
  160 #define F_INSN_SIZE(t)  ((sizeof (t))/sizeof(u_int32_t))
  161 
  162 /*
  163  * This is used to store an array of 16-bit entries (ports etc.)
  164  */
  165 typedef struct  _ipfw_insn_u16 {
  166         ipfw_insn o;
  167         u_int16_t ports[2];     /* there may be more */
  168 } ipfw_insn_u16;
  169 
  170 /*
  171  * This is used to store an array of 32-bit entries
  172  * (uid, single IPv4 addresses etc.)
  173  */
  174 typedef struct  _ipfw_insn_u32 {
  175         ipfw_insn o;
  176         u_int32_t d[1]; /* one or more */
  177 } ipfw_insn_u32;
  178 
  179 /*
  180  * This is used to store IP addr-mask pairs.
  181  */
  182 typedef struct  _ipfw_insn_ip {
  183         ipfw_insn o;
  184         struct in_addr  addr;
  185         struct in_addr  mask;
  186 } ipfw_insn_ip;
  187 
  188 /*
  189  * This is used to forward to a given address (ip)
  190  */
  191 typedef struct  _ipfw_insn_sa {
  192         ipfw_insn o;
  193         struct sockaddr_in sa;
  194 } ipfw_insn_sa;
  195 
  196 /*
  197  * This is used for MAC addr-mask pairs.
  198  */
  199 typedef struct  _ipfw_insn_mac {
  200         ipfw_insn o;
  201         u_char addr[12];        /* dst[6] + src[6] */
  202         u_char mask[12];        /* dst[6] + src[6] */
  203 } ipfw_insn_mac;
  204 
  205 /*
  206  * This is used for interface match rules (recv xx, xmit xx)
  207  */
  208 typedef struct  _ipfw_insn_if {
  209         ipfw_insn o;
  210         union {
  211                 struct in_addr ip;
  212                 int unit;
  213         } p;
  214         char name[IFNAMSIZ];
  215 } ipfw_insn_if;
  216 
  217 /*
  218  * This is used for pipe and queue actions, which need to store
  219  * a single pointer (which can have different size on different
  220  * architectures.
  221  */
  222 typedef struct  _ipfw_insn_pipe {
  223         ipfw_insn       o;
  224         void            *pipe_ptr;
  225 } ipfw_insn_pipe;
  226 
  227 /*
  228  * This is used for limit rules.
  229  */
  230 typedef struct  _ipfw_insn_limit {
  231         ipfw_insn o;
  232         u_int8_t _pad;
  233         u_int8_t limit_mask;    /* combination of DYN_* below   */
  234 #define DYN_SRC_ADDR    0x1
  235 #define DYN_SRC_PORT    0x2
  236 #define DYN_DST_ADDR    0x4
  237 #define DYN_DST_PORT    0x8
  238 
  239         u_int16_t conn_limit;
  240 } ipfw_insn_limit;
  241 
  242 /*
  243  * This is used for log instructions
  244  */
  245 typedef struct  _ipfw_insn_log {
  246         ipfw_insn o;
  247         u_int32_t max_log;      /* how many do we log -- 0 = all */
  248         u_int32_t log_left;     /* how many left to log         */
  249 } ipfw_insn_log;
  250 
  251 /*
  252  * Here we have the structure representing an ipfw rule.
  253  *
  254  * It starts with a general area (with link fields and counters)
  255  * followed by an array of one or more instructions, which the code
  256  * accesses as an array of 32-bit values.
  257  *
  258  * Given a rule pointer  r:
  259  *
  260  *  r->cmd              is the start of the first instruction.
  261  *  ACTION_PTR(r)       is the start of the first action (things to do
  262  *                      once a rule matched).
  263  *
  264  * When assembling instruction, remember the following:
  265  *
  266  *  + if a rule has a "keep-state" (or "limit") option, then the
  267  *      first instruction (at r->cmd) MUST BE an O_PROBE_STATE
  268  *  + if a rule has a "log" option, then the first action
  269  *      (at ACTION_PTR(r)) MUST be O_LOG
  270  *
  271  * NOTE: we use a simple linked list of rules because we never need
  272  *      to delete a rule without scanning the list. We do not use
  273  *      queue(3) macros for portability and readability.
  274  */
  275 
  276 struct ip_fw {
  277         struct ip_fw    *next;          /* linked list of rules         */
  278         struct ip_fw    *next_rule;     /* ptr to next [skipto] rule    */
  279         u_int32_t       set_disable;    /* disabled sets (for userland) */
  280         u_int16_t       act_ofs;        /* offset of action in 32-bit units */
  281         u_int16_t       cmd_len;        /* # of 32-bit words in cmd     */
  282         u_int16_t       rulenum;        /* rule number                  */
  283         u_int8_t        set;            /* rule set (0..31)             */
  284         u_int8_t        _pad;           /* padding                      */
  285 
  286         /* These fields are present in all rules.                       */
  287         u_int64_t       pcnt;           /* Packet counter               */
  288         u_int64_t       bcnt;           /* Byte counter                 */
  289         u_int32_t       timestamp;      /* tv_sec of last match         */
  290 
  291         ipfw_insn       cmd[1];         /* storage for commands         */
  292 };
  293 
  294 #define ACTION_PTR(rule)                                \
  295         (ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) )
  296 
  297 #define RULESIZE(rule)  (sizeof(struct ip_fw) + \
  298         ((struct ip_fw *)(rule))->cmd_len * 4 - 4)
  299 
  300 /*
  301  * This structure is used as a flow mask and a flow id for various
  302  * parts of the code.
  303  */
  304 struct ipfw_flow_id {
  305         u_int32_t       dst_ip;
  306         u_int32_t       src_ip;
  307         u_int16_t       dst_port;
  308         u_int16_t       src_port;
  309         u_int8_t        proto;
  310         u_int8_t        flags;  /* protocol-specific flags */
  311 };
  312 
  313 /*
  314  * dynamic ipfw rule
  315  */
  316 typedef struct _ipfw_dyn_rule ipfw_dyn_rule;
  317 
  318 struct _ipfw_dyn_rule {
  319         ipfw_dyn_rule   *next;          /* linked list of rules.        */
  320         struct ipfw_flow_id id;         /* (masked) flow id             */
  321         struct ip_fw *rule;             /* pointer to rule              */
  322         ipfw_dyn_rule *parent;          /* pointer to parent rule       */
  323         u_int32_t       expire;         /* expire time                  */
  324         u_int64_t       pcnt;           /* packet match counter         */
  325         u_int64_t       bcnt;           /* byte match counter           */
  326         u_int32_t       bucket;         /* which bucket in hash table   */
  327         u_int32_t       state;          /* state of this rule (typically a
  328                                          * combination of TCP flags)
  329                                          */
  330         u_int32_t       ack_fwd;        /* most recent ACKs in forward  */
  331         u_int32_t       ack_rev;        /* and reverse directions (used */
  332                                         /* to generate keepalives)      */
  333         u_int16_t       dyn_type;       /* rule type                    */
  334         u_int16_t       count;          /* refcount                     */
  335         u_int16_t       rulenum;        /* rule number (for userland)   */
  336 };
  337 
  338 /*
  339  * Definitions for IP option names.
  340  */
  341 #define IP_FW_IPOPT_LSRR        0x01
  342 #define IP_FW_IPOPT_SSRR        0x02
  343 #define IP_FW_IPOPT_RR          0x04
  344 #define IP_FW_IPOPT_TS          0x08
  345 
  346 /*
  347  * Definitions for TCP option names.
  348  */
  349 #define IP_FW_TCPOPT_MSS        0x01
  350 #define IP_FW_TCPOPT_WINDOW     0x02
  351 #define IP_FW_TCPOPT_SACK       0x04
  352 #define IP_FW_TCPOPT_TS         0x08
  353 #define IP_FW_TCPOPT_CC         0x10
  354 
  355 #define ICMP_REJECT_RST         0x100   /* fake ICMP code (send a TCP RST) */
  356 
  357 /*
  358  * Main firewall chains definitions and global var's definitions.
  359  */
  360 #ifdef _KERNEL
  361 
  362 #define IP_FW_PORT_DYNT_FLAG    0x10000
  363 #define IP_FW_PORT_TEE_FLAG     0x20000
  364 #define IP_FW_PORT_DENY_FLAG    0x40000
  365 
  366 /*
  367  * arguments for calling ipfw_chk() and dummynet_io(). We put them
  368  * all into a structure because this way it is easier and more
  369  * efficient to pass variables around and extend the interface.
  370  */
  371 struct ip_fw_args {
  372         struct mbuf     *m;             /* the mbuf chain               */
  373         struct ifnet    *oif;           /* output interface             */
  374         struct sockaddr_in *next_hop;   /* forward address              */
  375         struct ip_fw    *rule;          /* matching rule                */
  376         struct ether_header *eh;        /* for bridged packets          */
  377 
  378         struct route    *ro;            /* for dummynet                 */
  379         struct sockaddr_in *dst;        /* for dummynet                 */
  380         int flags;                      /* for dummynet                 */
  381 
  382         struct ipfw_flow_id f_id;       /* grabbed from IP header       */
  383         u_int16_t       divert_rule;    /* divert cookie                */
  384         u_int32_t       retval;
  385 };
  386 
  387 /*
  388  * Function definitions.
  389  */
  390 
  391 /* Firewall hooks */
  392 struct sockopt;
  393 struct dn_flow_set;
  394 
  395 void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */
  396 
  397 typedef int ip_fw_chk_t (struct ip_fw_args *args);
  398 typedef int ip_fw_ctl_t (struct sockopt *);
  399 extern ip_fw_chk_t *ip_fw_chk_ptr;
  400 extern ip_fw_ctl_t *ip_fw_ctl_ptr;
  401 extern int fw_one_pass;
  402 extern int fw_enable;
  403 #define IPFW_LOADED     (ip_fw_chk_ptr != NULL)
  404 #endif /* _KERNEL */
  405 
  406 #endif /* _IPFW2_H */

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