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: src/sys/netinet/ip_fw.h,v 1.76.2.1 2003/06/04 02:19:36 ticso Exp $
   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 metadata) 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  * Note that the code is written so that individual instructions
   41  * have a size which is a multiple of 32 bits. This means that, if
   42  * such structures contain pointers or other 64-bit entities,
   43  * (there is just one instance now) they may end up unaligned on
   44  * 64-bit architectures, so the must be handled with care.
   45  *
   46  * "enum ipfw_opcodes" are the opcodes supported. We can have up
   47  * to 256 different opcodes.
   48  */
   49 
   50 enum ipfw_opcodes {             /* arguments (4 byte each)      */
   51         O_NOP,
   52 
   53         O_IP_SRC,               /* u32 = IP                     */
   54         O_IP_SRC_MASK,          /* ip = IP/mask                 */
   55         O_IP_SRC_ME,            /* none                         */
   56         O_IP_SRC_SET,           /* u32=base, arg1=len, bitmap   */
   57 
   58         O_IP_DST,               /* u32 = IP                     */
   59         O_IP_DST_MASK,          /* ip = IP/mask                 */
   60         O_IP_DST_ME,            /* none                         */
   61         O_IP_DST_SET,           /* u32=base, arg1=len, bitmap   */
   62 
   63         O_IP_SRCPORT,           /* (n)port list:mask 4 byte ea  */
   64         O_IP_DSTPORT,           /* (n)port list:mask 4 byte ea  */
   65         O_PROTO,                /* arg1=protocol                */
   66 
   67         O_MACADDR2,             /* 2 mac addr:mask              */
   68         O_MAC_TYPE,             /* same as srcport              */
   69 
   70         O_LAYER2,               /* none                         */
   71         O_IN,                   /* none                         */
   72         O_FRAG,                 /* none                         */
   73 
   74         O_RECV,                 /* none                         */
   75         O_XMIT,                 /* none                         */
   76         O_VIA,                  /* none                         */
   77 
   78         O_IPOPT,                /* arg1 = 2*u8 bitmap           */
   79         O_IPLEN,                /* arg1 = len                   */
   80         O_IPID,                 /* arg1 = id                    */
   81 
   82         O_IPTOS,                /* arg1 = id                    */
   83         O_IPPRECEDENCE,         /* arg1 = precedence << 5       */
   84         O_IPTTL,                /* arg1 = TTL                   */
   85 
   86         O_IPVER,                /* arg1 = version               */
   87         O_UID,                  /* u32 = id                     */
   88         O_GID,                  /* u32 = id                     */
   89         O_ESTAB,                /* none (tcp established)       */
   90         O_TCPFLAGS,             /* arg1 = 2*u8 bitmap           */
   91         O_TCPWIN,               /* arg1 = desired win           */
   92         O_TCPSEQ,               /* u32 = desired seq.           */
   93         O_TCPACK,               /* u32 = desired seq.           */
   94         O_ICMPTYPE,             /* u32 = icmp bitmap            */
   95         O_TCPOPTS,              /* arg1 = 2*u8 bitmap           */
   96 
   97         O_VERREVPATH,           /* none                         */
   98 
   99         O_PROBE_STATE,          /* none                         */
  100         O_KEEP_STATE,           /* none                         */
  101         O_LIMIT,                /* ipfw_insn_limit              */
  102         O_LIMIT_PARENT,         /* dyn_type, not an opcode.     */
  103         /*
  104          * these are really 'actions', and must be last in the list.
  105          */
  106 
  107         O_LOG,                  /* ipfw_insn_log                */
  108         O_PROB,                 /* u32 = match probability      */
  109 
  110         O_CHECK_STATE,          /* none                         */
  111         O_ACCEPT,               /* none                         */
  112         O_DENY,                 /* none                         */
  113         O_REJECT,               /* arg1=icmp arg (same as deny) */
  114         O_COUNT,                /* none                         */
  115         O_SKIPTO,               /* arg1=next rule number        */
  116         O_PIPE,                 /* arg1=pipe number             */
  117         O_QUEUE,                /* arg1=queue number            */
  118         O_DIVERT,               /* arg1=port number             */
  119         O_TEE,                  /* arg1=port number             */
  120         O_FORWARD_IP,           /* fwd sockaddr                 */
  121         O_FORWARD_MAC,          /* fwd mac                      */
  122         O_LAST_OPCODE           /* not an opcode!               */
  123 };
  124 
  125 /*
  126  * Template for instructions.
  127  *
  128  * ipfw_insn is used for all instructions which require no operands,
  129  * a single 16-bit value (arg1), or a couple of 8-bit values.
  130  *
  131  * For other instructions which require different/larger arguments
  132  * we have derived structures, ipfw_insn_*.
  133  *
  134  * The size of the instruction (in 32-bit words) is in the low
  135  * 6 bits of "len". The 2 remaining bits are used to implement
  136  * NOT and OR on individual instructions. Given a type, you can
  137  * compute the length to be put in "len" using F_INSN_SIZE(t)
  138  *
  139  * F_NOT        negates the match result of the instruction.
  140  *
  141  * F_OR         is used to build or blocks. By default, instructions
  142  *              are evaluated as part of a logical AND. An "or" block
  143  *              { X or Y or Z } contains F_OR set in all but the last
  144  *              instruction of the block. A match will cause the code
  145  *              to skip past the last instruction of the block.
  146  *
  147  * NOTA BENE: in a couple of places we assume that
  148  *      sizeof(ipfw_insn) == sizeof(u_int32_t)
  149  * this needs to be fixed.
  150  *
  151  */
  152 typedef struct  _ipfw_insn {    /* template for instructions */
  153         enum ipfw_opcodes       opcode:8;
  154         u_int8_t        len;    /* numer of 32-byte words */
  155 #define F_NOT           0x80
  156 #define F_OR            0x40
  157 #define F_LEN_MASK      0x3f
  158 #define F_LEN(cmd)      ((cmd)->len & F_LEN_MASK)
  159 
  160         u_int16_t       arg1;
  161 } ipfw_insn;
  162 
  163 /*
  164  * The F_INSN_SIZE(type) computes the size, in 4-byte words, of
  165  * a given type.
  166  */
  167 #define F_INSN_SIZE(t)  ((sizeof (t))/sizeof(u_int32_t))
  168 
  169 /*
  170  * This is used to store an array of 16-bit entries (ports etc.)
  171  */
  172 typedef struct  _ipfw_insn_u16 {
  173         ipfw_insn o;
  174         u_int16_t ports[2];     /* there may be more */
  175 } ipfw_insn_u16;
  176 
  177 /*
  178  * This is used to store an array of 32-bit entries
  179  * (uid, single IPv4 addresses etc.)
  180  */
  181 typedef struct  _ipfw_insn_u32 {
  182         ipfw_insn o;
  183         u_int32_t d[1]; /* one or more */
  184 } ipfw_insn_u32;
  185 
  186 /*
  187  * This is used to store IP addr-mask pairs.
  188  */
  189 typedef struct  _ipfw_insn_ip {
  190         ipfw_insn o;
  191         struct in_addr  addr;
  192         struct in_addr  mask;
  193 } ipfw_insn_ip;
  194 
  195 /*
  196  * This is used to forward to a given address (ip)
  197  */
  198 typedef struct  _ipfw_insn_sa {
  199         ipfw_insn o;
  200         struct sockaddr_in sa;
  201 } ipfw_insn_sa;
  202 
  203 /*
  204  * This is used for MAC addr-mask pairs.
  205  */
  206 typedef struct  _ipfw_insn_mac {
  207         ipfw_insn o;
  208         u_char addr[12];        /* dst[6] + src[6] */
  209         u_char mask[12];        /* dst[6] + src[6] */
  210 } ipfw_insn_mac;
  211 
  212 /*
  213  * This is used for interface match rules (recv xx, xmit xx)
  214  */
  215 typedef struct  _ipfw_insn_if {
  216         ipfw_insn o;
  217         union {
  218                 struct in_addr ip;
  219                 int32_t unit;
  220         } p;
  221         char name[IFNAMSIZ];
  222 } ipfw_insn_if;
  223 
  224 /*
  225  * This is used for pipe and queue actions, which need to store
  226  * a single pointer (which can have different size on different
  227  * architectures.
  228  * Note that, because of previous instructions, pipe_ptr might
  229  * be unaligned in the overall structure, so it needs to be
  230  * manipulated with care.
  231  */
  232 typedef struct  _ipfw_insn_pipe {
  233         ipfw_insn       o;
  234         void            *pipe_ptr;      /* XXX */
  235 } ipfw_insn_pipe;
  236 
  237 /*
  238  * This is used for limit rules.
  239  */
  240 typedef struct  _ipfw_insn_limit {
  241         ipfw_insn o;
  242         u_int8_t _pad;
  243         u_int8_t limit_mask;    /* combination of DYN_* below   */
  244 #define DYN_SRC_ADDR    0x1
  245 #define DYN_SRC_PORT    0x2
  246 #define DYN_DST_ADDR    0x4
  247 #define DYN_DST_PORT    0x8
  248 
  249         u_int16_t conn_limit;
  250 } ipfw_insn_limit;
  251 
  252 /*
  253  * This is used for log instructions
  254  */
  255 typedef struct  _ipfw_insn_log {
  256         ipfw_insn o;
  257         u_int32_t max_log;      /* how many do we log -- 0 = all */
  258         u_int32_t log_left;     /* how many left to log         */
  259 } ipfw_insn_log;
  260 
  261 /*
  262  * Here we have the structure representing an ipfw rule.
  263  *
  264  * It starts with a general area (with link fields and counters)
  265  * followed by an array of one or more instructions, which the code
  266  * accesses as an array of 32-bit values.
  267  *
  268  * Given a rule pointer  r:
  269  *
  270  *  r->cmd              is the start of the first instruction.
  271  *  ACTION_PTR(r)       is the start of the first action (things to do
  272  *                      once a rule matched).
  273  *
  274  * When assembling instruction, remember the following:
  275  *
  276  *  + if a rule has a "keep-state" (or "limit") option, then the
  277  *      first instruction (at r->cmd) MUST BE an O_PROBE_STATE
  278  *  + if a rule has a "log" option, then the first action
  279  *      (at ACTION_PTR(r)) MUST be O_LOG
  280  *
  281  * NOTE: we use a simple linked list of rules because we never need
  282  *      to delete a rule without scanning the list. We do not use
  283  *      queue(3) macros for portability and readability.
  284  */
  285 
  286 struct ip_fw {
  287         struct ip_fw    *next;          /* linked list of rules         */
  288         struct ip_fw    *next_rule;     /* ptr to next [skipto] rule    */
  289 #if 0   /* passed up using 'next_rule' */
  290         u_int32_t       set_disable;    /* disabled sets (for userland) */
  291 #endif
  292         u_int16_t       act_ofs;        /* offset of action in 32-bit units */
  293         u_int16_t       cmd_len;        /* # of 32-bit words in cmd     */
  294         u_int16_t       rulenum;        /* rule number                  */
  295         u_int8_t        set;            /* rule set (0..31)             */
  296         u_int8_t        _pad;           /* padding                      */
  297 
  298         /* These fields are present in all rules.                       */
  299         u_int64_t       pcnt;           /* Packet counter               */
  300         u_int64_t       bcnt;           /* Byte counter                 */
  301         u_int32_t       timestamp;      /* tv_sec of last match         */
  302 
  303         ipfw_insn       cmd[1];         /* storage for commands         */
  304 };
  305 
  306 #define ACTION_PTR(rule)                                \
  307         (ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) )
  308 
  309 #define RULESIZE(rule)  (sizeof(struct ip_fw) + \
  310         ((struct ip_fw *)(rule))->cmd_len * 4 - 4)
  311 
  312 /*
  313  * This structure is used as a flow mask and a flow id for various
  314  * parts of the code.
  315  */
  316 struct ipfw_flow_id {
  317         u_int32_t       dst_ip;
  318         u_int32_t       src_ip;
  319         u_int16_t       dst_port;
  320         u_int16_t       src_port;
  321         u_int8_t        proto;
  322         u_int8_t        flags;  /* protocol-specific flags */
  323 };
  324 
  325 /*
  326  * dynamic ipfw rule
  327  */
  328 typedef struct _ipfw_dyn_rule ipfw_dyn_rule;
  329 
  330 struct _ipfw_dyn_rule {
  331         ipfw_dyn_rule   *next;          /* linked list of rules.        */
  332         struct ip_fw *rule;             /* pointer to rule              */
  333         ipfw_dyn_rule *parent;          /* pointer to parent rule       */
  334         u_int64_t       pcnt;           /* packet match counter         */
  335         u_int64_t       bcnt;           /* byte match counter           */
  336         struct ipfw_flow_id id;         /* (masked) flow id             */
  337         u_int32_t       expire;         /* expire time                  */
  338         u_int32_t       bucket;         /* which bucket in hash table   */
  339         u_int32_t       state;          /* state of this rule (typically a
  340                                          * combination of TCP flags)
  341                                          */
  342         u_int32_t       ack_fwd;        /* most recent ACKs in forward  */
  343         u_int32_t       ack_rev;        /* and reverse directions (used */
  344                                         /* to generate keepalives)      */
  345         u_int16_t       dyn_type;       /* rule type                    */
  346         u_int16_t       count;          /* refcount                     */
  347 #if 0   /* passed up with 'rule' */
  348         u_int16_t       rulenum;        /* rule number (for userland)   */
  349 #endif
  350 };
  351 
  352 /*
  353  * Definitions for IP option names.
  354  */
  355 #define IP_FW_IPOPT_LSRR        0x01
  356 #define IP_FW_IPOPT_SSRR        0x02
  357 #define IP_FW_IPOPT_RR          0x04
  358 #define IP_FW_IPOPT_TS          0x08
  359 
  360 /*
  361  * Definitions for TCP option names.
  362  */
  363 #define IP_FW_TCPOPT_MSS        0x01
  364 #define IP_FW_TCPOPT_WINDOW     0x02
  365 #define IP_FW_TCPOPT_SACK       0x04
  366 #define IP_FW_TCPOPT_TS         0x08
  367 #define IP_FW_TCPOPT_CC         0x10
  368 
  369 #define ICMP_REJECT_RST         0x100   /* fake ICMP code (send a TCP RST) */
  370 
  371 /*
  372  * Main firewall chains definitions and global var's definitions.
  373  */
  374 #ifdef _KERNEL
  375 
  376 #define IP_FW_PORT_DYNT_FLAG    0x10000
  377 #define IP_FW_PORT_TEE_FLAG     0x20000
  378 #define IP_FW_PORT_DENY_FLAG    0x40000
  379 
  380 /*
  381  * arguments for calling ipfw_chk() and dummynet_io(). We put them
  382  * all into a structure because this way it is easier and more
  383  * efficient to pass variables around and extend the interface.
  384  */
  385 struct ip_fw_args {
  386         struct mbuf     *m;             /* the mbuf chain               */
  387         struct ifnet    *oif;           /* output interface             */
  388         struct sockaddr_in *next_hop;   /* forward address              */
  389         struct ip_fw    *rule;          /* matching rule                */
  390         struct ether_header *eh;        /* for bridged packets          */
  391 
  392         struct route    *ro;            /* for dummynet                 */
  393         struct sockaddr_in *dst;        /* for dummynet                 */
  394         int flags;                      /* for dummynet                 */
  395 
  396         struct ipfw_flow_id f_id;       /* grabbed from IP header       */
  397         u_int16_t       divert_rule;    /* divert cookie                */
  398         u_int32_t       retval;
  399 };
  400 
  401 /*
  402  * Function definitions.
  403  */
  404 
  405 /* Firewall hooks */
  406 struct sockopt;
  407 struct dn_flow_set;
  408 
  409 void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */
  410 
  411 typedef int ip_fw_chk_t (struct ip_fw_args *args);
  412 typedef int ip_fw_ctl_t (struct sockopt *);
  413 extern ip_fw_chk_t *ip_fw_chk_ptr;
  414 extern ip_fw_ctl_t *ip_fw_ctl_ptr;
  415 extern int fw_one_pass;
  416 extern int fw_enable;
  417 #define IPFW_LOADED     (ip_fw_chk_ptr != NULL)
  418 #endif /* _KERNEL */
  419 
  420 #endif /* _IPFW2_H */

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