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_fw2.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 * $FreeBSD$ 26 */ 27 28 #ifndef _IPFW2_H 29 #define _IPFW2_H 30 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 /* 105 * These are really 'actions'. 106 */ 107 108 O_LOG, /* ipfw_insn_log */ 109 O_PROB, /* u32 = match probability */ 110 111 O_CHECK_STATE, /* none */ 112 O_ACCEPT, /* none */ 113 O_DENY, /* none */ 114 O_REJECT, /* arg1=icmp arg (same as deny) */ 115 O_COUNT, /* none */ 116 O_SKIPTO, /* arg1=next rule number */ 117 O_PIPE, /* arg1=pipe number */ 118 O_QUEUE, /* arg1=queue number */ 119 O_DIVERT, /* arg1=port number */ 120 O_TEE, /* arg1=port number */ 121 O_FORWARD_IP, /* fwd sockaddr */ 122 O_FORWARD_MAC, /* fwd mac */ 123 124 /* 125 * More opcodes. 126 */ 127 O_IPSEC, /* has ipsec history */ 128 O_IP_SRC_LOOKUP, /* arg1=table number, u32=value */ 129 O_IP_DST_LOOKUP, /* arg1=table number, u32=value */ 130 131 O_LAST_OPCODE /* not an opcode! */ 132 }; 133 134 /* 135 * Template for instructions. 136 * 137 * ipfw_insn is used for all instructions which require no operands, 138 * a single 16-bit value (arg1), or a couple of 8-bit values. 139 * 140 * For other instructions which require different/larger arguments 141 * we have derived structures, ipfw_insn_*. 142 * 143 * The size of the instruction (in 32-bit words) is in the low 144 * 6 bits of "len". The 2 remaining bits are used to implement 145 * NOT and OR on individual instructions. Given a type, you can 146 * compute the length to be put in "len" using F_INSN_SIZE(t) 147 * 148 * F_NOT negates the match result of the instruction. 149 * 150 * F_OR is used to build or blocks. By default, instructions 151 * are evaluated as part of a logical AND. An "or" block 152 * { X or Y or Z } contains F_OR set in all but the last 153 * instruction of the block. A match will cause the code 154 * to skip past the last instruction of the block. 155 * 156 * NOTA BENE: in a couple of places we assume that 157 * sizeof(ipfw_insn) == sizeof(u_int32_t) 158 * this needs to be fixed. 159 * 160 */ 161 typedef struct _ipfw_insn { /* template for instructions */ 162 enum ipfw_opcodes opcode:8; 163 u_int8_t len; /* numer of 32-byte words */ 164 #define F_NOT 0x80 165 #define F_OR 0x40 166 #define F_LEN_MASK 0x3f 167 #define F_LEN(cmd) ((cmd)->len & F_LEN_MASK) 168 169 u_int16_t arg1; 170 } ipfw_insn; 171 172 /* 173 * The F_INSN_SIZE(type) computes the size, in 4-byte words, of 174 * a given type. 175 */ 176 #define F_INSN_SIZE(t) ((sizeof (t))/sizeof(u_int32_t)) 177 178 /* 179 * This is used to store an array of 16-bit entries (ports etc.) 180 */ 181 typedef struct _ipfw_insn_u16 { 182 ipfw_insn o; 183 u_int16_t ports[2]; /* there may be more */ 184 } ipfw_insn_u16; 185 186 /* 187 * This is used to store an array of 32-bit entries 188 * (uid, single IPv4 addresses etc.) 189 */ 190 typedef struct _ipfw_insn_u32 { 191 ipfw_insn o; 192 u_int32_t d[1]; /* one or more */ 193 } ipfw_insn_u32; 194 195 /* 196 * This is used to store IP addr-mask pairs. 197 */ 198 typedef struct _ipfw_insn_ip { 199 ipfw_insn o; 200 struct in_addr addr; 201 struct in_addr mask; 202 } ipfw_insn_ip; 203 204 /* 205 * This is used to forward to a given address (ip). 206 */ 207 typedef struct _ipfw_insn_sa { 208 ipfw_insn o; 209 struct sockaddr_in sa; 210 } ipfw_insn_sa; 211 212 /* 213 * This is used for MAC addr-mask pairs. 214 */ 215 typedef struct _ipfw_insn_mac { 216 ipfw_insn o; 217 u_char addr[12]; /* dst[6] + src[6] */ 218 u_char mask[12]; /* dst[6] + src[6] */ 219 } ipfw_insn_mac; 220 221 /* 222 * This is used for interface match rules (recv xx, xmit xx). 223 */ 224 typedef struct _ipfw_insn_if { 225 ipfw_insn o; 226 union { 227 struct in_addr ip; 228 int32_t unit; 229 } p; 230 char name[IFNAMSIZ]; 231 } ipfw_insn_if; 232 233 /* 234 * This is used for pipe and queue actions, which need to store 235 * a single pointer (which can have different size on different 236 * architectures. 237 * Note that, because of previous instructions, pipe_ptr might 238 * be unaligned in the overall structure, so it needs to be 239 * manipulated with care. 240 */ 241 typedef struct _ipfw_insn_pipe { 242 ipfw_insn o; 243 void *pipe_ptr; /* XXX */ 244 } ipfw_insn_pipe; 245 246 /* 247 * This is used for limit rules. 248 */ 249 typedef struct _ipfw_insn_limit { 250 ipfw_insn o; 251 u_int8_t _pad; 252 u_int8_t limit_mask; /* combination of DYN_* below */ 253 #define DYN_SRC_ADDR 0x1 254 #define DYN_SRC_PORT 0x2 255 #define DYN_DST_ADDR 0x4 256 #define DYN_DST_PORT 0x8 257 258 u_int16_t conn_limit; 259 } ipfw_insn_limit; 260 261 /* 262 * This is used for log instructions. 263 */ 264 typedef struct _ipfw_insn_log { 265 ipfw_insn o; 266 u_int32_t max_log; /* how many do we log -- 0 = all */ 267 u_int32_t log_left; /* how many left to log */ 268 } ipfw_insn_log; 269 270 /* 271 * Here we have the structure representing an ipfw rule. 272 * 273 * It starts with a general area (with link fields and counters) 274 * followed by an array of one or more instructions, which the code 275 * accesses as an array of 32-bit values. 276 * 277 * Given a rule pointer r: 278 * 279 * r->cmd is the start of the first instruction. 280 * ACTION_PTR(r) is the start of the first action (things to do 281 * once a rule matched). 282 * 283 * When assembling instruction, remember the following: 284 * 285 * + if a rule has a "keep-state" (or "limit") option, then the 286 * first instruction (at r->cmd) MUST BE an O_PROBE_STATE 287 * + if a rule has a "log" option, then the first action 288 * (at ACTION_PTR(r)) MUST be O_LOG 289 * 290 * NOTE: we use a simple linked list of rules because we never need 291 * to delete a rule without scanning the list. We do not use 292 * queue(3) macros for portability and readability. 293 */ 294 295 struct ip_fw { 296 struct ip_fw *next; /* linked list of rules */ 297 struct ip_fw *next_rule; /* ptr to next [skipto] rule */ 298 /* 'next_rule' is used to pass up 'set_disable' status */ 299 300 u_int16_t act_ofs; /* offset of action in 32-bit units */ 301 u_int16_t cmd_len; /* # of 32-bit words in cmd */ 302 u_int16_t rulenum; /* rule number */ 303 u_int8_t set; /* rule set (0..31) */ 304 #define RESVD_SET 31 /* set for default and persistent rules */ 305 u_int8_t _pad; /* padding */ 306 307 /* These fields are present in all rules. */ 308 u_int64_t pcnt; /* Packet counter */ 309 u_int64_t bcnt; /* Byte counter */ 310 u_int32_t timestamp; /* tv_sec of last match */ 311 312 ipfw_insn cmd[1]; /* storage for commands */ 313 }; 314 315 #define ACTION_PTR(rule) \ 316 (ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) ) 317 318 #define RULESIZE(rule) (sizeof(struct ip_fw) + \ 319 ((struct ip_fw *)(rule))->cmd_len * 4 - 4) 320 321 /* 322 * This structure is used as a flow mask and a flow id for various 323 * parts of the code. 324 */ 325 struct ipfw_flow_id { 326 u_int32_t dst_ip; 327 u_int32_t src_ip; 328 u_int16_t dst_port; 329 u_int16_t src_port; 330 u_int8_t proto; 331 u_int8_t flags; /* protocol-specific flags */ 332 }; 333 334 /* 335 * Dynamic ipfw rule. 336 */ 337 typedef struct _ipfw_dyn_rule ipfw_dyn_rule; 338 339 struct _ipfw_dyn_rule { 340 ipfw_dyn_rule *next; /* linked list of rules. */ 341 struct ip_fw *rule; /* pointer to rule */ 342 /* 'rule' is used to pass up the rule number (from the parent) */ 343 344 ipfw_dyn_rule *parent; /* pointer to parent rule */ 345 u_int64_t pcnt; /* packet match counter */ 346 u_int64_t bcnt; /* byte match counter */ 347 struct ipfw_flow_id id; /* (masked) flow id */ 348 u_int32_t expire; /* expire time */ 349 u_int32_t bucket; /* which bucket in hash table */ 350 u_int32_t state; /* state of this rule (typically a 351 * combination of TCP flags) 352 */ 353 u_int32_t ack_fwd; /* most recent ACKs in forward */ 354 u_int32_t ack_rev; /* and reverse directions (used */ 355 /* to generate keepalives) */ 356 u_int16_t dyn_type; /* rule type */ 357 u_int16_t count; /* refcount */ 358 }; 359 360 /* 361 * Definitions for IP option names. 362 */ 363 #define IP_FW_IPOPT_LSRR 0x01 364 #define IP_FW_IPOPT_SSRR 0x02 365 #define IP_FW_IPOPT_RR 0x04 366 #define IP_FW_IPOPT_TS 0x08 367 368 /* 369 * Definitions for TCP option names. 370 */ 371 #define IP_FW_TCPOPT_MSS 0x01 372 #define IP_FW_TCPOPT_WINDOW 0x02 373 #define IP_FW_TCPOPT_SACK 0x04 374 #define IP_FW_TCPOPT_TS 0x08 375 #define IP_FW_TCPOPT_CC 0x10 376 377 #define ICMP_REJECT_RST 0x100 /* fake ICMP code (send a TCP RST) */ 378 379 /* 380 * These are used for lookup tables. 381 */ 382 typedef struct _ipfw_table_entry { 383 in_addr_t addr; /* network address */ 384 u_int32_t value; /* value */ 385 u_int16_t tbl; /* table number */ 386 u_int8_t masklen; /* mask length */ 387 } ipfw_table_entry; 388 389 typedef struct _ipfw_table { 390 u_int32_t size; /* size of entries in bytes */ 391 u_int32_t cnt; /* # of entries */ 392 u_int16_t tbl; /* table number */ 393 ipfw_table_entry ent[0]; /* entries */ 394 } ipfw_table; 395 396 /* 397 * Main firewall chains definitions and global var's definitions. 398 */ 399 #ifdef _KERNEL 400 401 #define IP_FW_PORT_DYNT_FLAG 0x10000 402 #define IP_FW_PORT_TEE_FLAG 0x20000 403 #define IP_FW_PORT_DENY_FLAG 0x40000 404 405 /* 406 * Arguments for calling ipfw_chk() and dummynet_io(). We put them 407 * all into a structure because this way it is easier and more 408 * efficient to pass variables around and extend the interface. 409 */ 410 struct ip_fw_args { 411 struct mbuf *m; /* the mbuf chain */ 412 struct ifnet *oif; /* output interface */ 413 struct sockaddr_in *next_hop; /* forward address */ 414 struct ip_fw *rule; /* matching rule */ 415 struct ether_header *eh; /* for bridged packets */ 416 417 struct route *ro; /* for dummynet */ 418 struct sockaddr_in *dst; /* for dummynet */ 419 int flags; /* for dummynet */ 420 421 struct ipfw_flow_id f_id; /* grabbed from IP header */ 422 u_int16_t divert_rule; /* divert cookie */ 423 u_int32_t retval; 424 }; 425 426 /* 427 * Function definitions. 428 */ 429 430 /* Firewall hooks */ 431 struct sockopt; 432 struct dn_flow_set; 433 434 void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */ 435 436 typedef int ip_fw_chk_t (struct ip_fw_args *args); 437 typedef int ip_fw_ctl_t (struct sockopt *); 438 extern ip_fw_chk_t *ip_fw_chk_ptr; 439 extern ip_fw_ctl_t *ip_fw_ctl_ptr; 440 extern int fw_one_pass; 441 extern int fw_enable; 442 #define IPFW_LOADED (ip_fw_chk_ptr != NULL) 443 #endif /* _KERNEL */ 444 445 #endif /* _IPFW2_H */
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