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