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 O_IPOPTS, /* arg1 = 2*u8 bitmap */ 92 93 O_PROBE_STATE, /* none */ 94 O_KEEP_STATE, /* none */ 95 O_LIMIT, /* ipfw_insn_limit */ 96 O_LIMIT_PARENT, /* dyn_type, not an opcode. */ 97 /* 98 * these are really 'actions', and must be last in the list. 99 */ 100 101 O_LOG, /* ipfw_insn_log */ 102 O_PROB, /* u32 = match probability */ 103 104 O_CHECK_STATE, /* none */ 105 O_ACCEPT, /* none */ 106 O_DENY, /* none */ 107 O_REJECT, /* arg1=icmp arg (same as deny) */ 108 O_COUNT, /* none */ 109 O_SKIPTO, /* arg1=next rule number */ 110 O_PIPE, /* arg1=pipe number */ 111 O_QUEUE, /* arg1=queue number */ 112 O_DIVERT, /* arg1=port number */ 113 O_TEE, /* arg1=port number */ 114 O_FORWARD_IP, /* fwd sockaddr */ 115 O_FORWARD_MAC, /* fwd mac */ 116 O_LAST_OPCODE /* not an opcode! */ 117 }; 118 119 /* 120 * Template for instructions. 121 * 122 * ipfw_insn is used for all instructions which require no operands, 123 * a single 16-bit value (arg1), or a couple of 8-bit values. 124 * 125 * For other instructions which require different/larger arguments 126 * we have derived structures, ipfw_insn_*. 127 * 128 * The size of the instruction (in 32-bit words) is in the low 129 * 6 bits of "len". The 2 remaining bits are used to implement 130 * NOT and OR on individual instructions. Given a type, you can 131 * compute the length to be put in "len" using F_INSN_SIZE(t) 132 * 133 * F_NOT negates the match result of the instruction. 134 * 135 * F_OR is used to build or blocks. By default, instructions 136 * are evaluated as part of a logical AND. An "or" block 137 * { X or Y or Z } contains F_OR set in all but the last 138 * instruction of the block. A match will cause the code 139 * to skip past the last instruction of the block. 140 * 141 * NOTA BENE: in a couple of places we assume that 142 * sizeof(ipfw_insn) == sizeof(u_int32_t) 143 * this needs to be fixed. 144 * 145 */ 146 typedef struct _ipfw_insn { /* template for instructions */ 147 enum ipfw_opcodes opcode:8; 148 u_int8_t len; /* numer of 32-byte words */ 149 #define F_NOT 0x80 150 #define F_OR 0x40 151 #define F_LEN_MASK 0x3f 152 #define F_LEN(cmd) ((cmd)->len & F_LEN_MASK) 153 154 u_int16_t arg1; 155 } ipfw_insn; 156 157 /* 158 * The F_INSN_SIZE(type) computes the size, in 4-byte words, of 159 * a given type. 160 */ 161 #define F_INSN_SIZE(t) ((sizeof (t))/sizeof(u_int32_t)) 162 163 /* 164 * This is used to store an array of 16-bit entries (ports etc.) 165 */ 166 typedef struct _ipfw_insn_u16 { 167 ipfw_insn o; 168 u_int16_t ports[2]; /* there may be more */ 169 } ipfw_insn_u16; 170 171 /* 172 * This is used to store an array of 32-bit entries 173 * (uid, single IPv4 addresses etc.) 174 */ 175 typedef struct _ipfw_insn_u32 { 176 ipfw_insn o; 177 u_int32_t d[1]; /* one or more */ 178 } ipfw_insn_u32; 179 180 /* 181 * This is used to store IP addr-mask pairs. 182 */ 183 typedef struct _ipfw_insn_ip { 184 ipfw_insn o; 185 struct in_addr addr; 186 struct in_addr mask; 187 } ipfw_insn_ip; 188 189 /* 190 * This is used to forward to a given address (ip) 191 */ 192 typedef struct _ipfw_insn_sa { 193 ipfw_insn o; 194 struct sockaddr_in sa; 195 } ipfw_insn_sa; 196 197 /* 198 * This is used for MAC addr-mask pairs. 199 */ 200 typedef struct _ipfw_insn_mac { 201 ipfw_insn o; 202 u_char addr[12]; /* dst[6] + src[6] */ 203 u_char mask[12]; /* dst[6] + src[6] */ 204 } ipfw_insn_mac; 205 206 /* 207 * This is used for interface match rules (recv xx, xmit xx) 208 */ 209 typedef struct _ipfw_insn_if { 210 ipfw_insn o; 211 union { 212 struct in_addr ip; 213 int unit; 214 } p; 215 char name[IFNAMSIZ]; 216 } ipfw_insn_if; 217 218 /* 219 * This is used for pipe and queue actions, which need to store 220 * a single pointer (which can have different size on different 221 * architectures. 222 */ 223 typedef struct _ipfw_insn_pipe { 224 ipfw_insn o; 225 void *pipe_ptr; 226 } ipfw_insn_pipe; 227 228 /* 229 * This is used for limit rules. 230 */ 231 typedef struct _ipfw_insn_limit { 232 ipfw_insn o; 233 u_int8_t _pad; 234 u_int8_t limit_mask; /* combination of DYN_* below */ 235 #define DYN_SRC_ADDR 0x1 236 #define DYN_SRC_PORT 0x2 237 #define DYN_DST_ADDR 0x4 238 #define DYN_DST_PORT 0x8 239 240 u_int16_t conn_limit; 241 } ipfw_insn_limit; 242 243 /* 244 * This is used for log instructions 245 */ 246 typedef struct _ipfw_insn_log { 247 ipfw_insn o; 248 u_int32_t max_log; /* how many do we log -- 0 = all */ 249 u_int32_t log_left; /* how many left to log */ 250 } ipfw_insn_log; 251 252 /* 253 * Here we have the structure representing an ipfw rule. 254 * 255 * It starts with a general area (with link fields and counters) 256 * followed by an array of one or more instructions, which the code 257 * accesses as an array of 32-bit values. 258 * 259 * Given a rule pointer r: 260 * 261 * r->cmd is the start of the first instruction. 262 * ACTION_PTR(r) is the start of the first action (things to do 263 * once a rule matched). 264 * 265 * When assembling instruction, remember the following: 266 * 267 * + if a rule has a "keep-state" (or "limit") option, then the 268 * first instruction (at r->cmd) MUST BE an O_PROBE_STATE 269 * + if a rule has a "log" option, then the first action 270 * (at ACTION_PTR(r)) MUST be O_LOG 271 * 272 * NOTE: we use a simple linked list of rules because we never need 273 * to delete a rule without scanning the list. We do not use 274 * queue(3) macros for portability and readability. 275 */ 276 277 struct ip_fw { 278 struct ip_fw *next; /* linked list of rules */ 279 struct ip_fw *next_rule; /* ptr to next [skipto] rule */ 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_int16_t _pad; /* padding */ 284 285 /* These fields are present in all rules. */ 286 u_int64_t pcnt; /* Packet counter */ 287 u_int64_t bcnt; /* Byte counter */ 288 u_int32_t timestamp; /* tv_sec of last match */ 289 290 ipfw_insn cmd[1]; /* storage for commands */ 291 }; 292 293 #define ACTION_PTR(rule) \ 294 (ipfw_insn *)( (u_int32_t *)((rule)->cmd) + ((rule)->act_ofs) ) 295 296 #define RULESIZE(rule) (sizeof(struct ip_fw) + \ 297 ((struct ip_fw *)(rule))->cmd_len * 4 - 4) 298 299 /* 300 * This structure is used as a flow mask and a flow id for various 301 * parts of the code. 302 */ 303 struct ipfw_flow_id { 304 u_int32_t dst_ip; 305 u_int32_t src_ip; 306 u_int16_t dst_port; 307 u_int16_t src_port; 308 u_int8_t proto; 309 u_int8_t flags; /* protocol-specific flags */ 310 }; 311 312 /* 313 * dynamic ipfw rule 314 */ 315 typedef struct _ipfw_dyn_rule ipfw_dyn_rule; 316 317 struct _ipfw_dyn_rule { 318 ipfw_dyn_rule *next; /* linked list of rules. */ 319 struct ipfw_flow_id id; /* (masked) flow id */ 320 struct ip_fw *rule; /* pointer to rule */ 321 ipfw_dyn_rule *parent; /* pointer to parent rule */ 322 u_int32_t expire; /* expire time */ 323 u_int64_t pcnt; /* packet match counter */ 324 u_int64_t bcnt; /* byte match counter */ 325 u_int32_t bucket; /* which bucket in hash table */ 326 u_int32_t state; /* state of this rule (typically a 327 * combination of TCP flags) 328 */ 329 u_int32_t ack_fwd; /* most recent ACKs in forward */ 330 u_int32_t ack_rev; /* and reverse directions (used */ 331 /* to generate keepalives) */ 332 u_int16_t dyn_type; /* rule type */ 333 u_int16_t count; /* refcount */ 334 }; 335 336 /* 337 * Definitions for IP option names. 338 */ 339 #define IP_FW_IPOPT_LSRR 0x01 340 #define IP_FW_IPOPT_SSRR 0x02 341 #define IP_FW_IPOPT_RR 0x04 342 #define IP_FW_IPOPT_TS 0x08 343 344 /* 345 * Definitions for TCP option names. 346 */ 347 #define IP_FW_TCPOPT_MSS 0x01 348 #define IP_FW_TCPOPT_WINDOW 0x02 349 #define IP_FW_TCPOPT_SACK 0x04 350 #define IP_FW_TCPOPT_TS 0x08 351 #define IP_FW_TCPOPT_CC 0x10 352 353 #define ICMP_REJECT_RST 0x100 /* fake ICMP code (send a TCP RST) */ 354 355 /* 356 * Main firewall chains definitions and global var's definitions. 357 */ 358 #ifdef _KERNEL 359 360 #define IP_FW_PORT_DYNT_FLAG 0x10000 361 #define IP_FW_PORT_TEE_FLAG 0x20000 362 #define IP_FW_PORT_DENY_FLAG 0x40000 363 364 /* 365 * arguments for calling ipfw_chk() and dummynet_io(). We put them 366 * all into a structure because this way it is easier and more 367 * efficient to pass variables around and extend the interface. 368 */ 369 struct ip_fw_args { 370 struct mbuf *m; /* the mbuf chain */ 371 struct ifnet *oif; /* output interface */ 372 struct sockaddr_in *next_hop; /* forward address */ 373 struct ip_fw *rule; /* matching rule */ 374 struct ether_header *eh; /* for bridged packets */ 375 376 struct route *ro; /* for dummynet */ 377 struct sockaddr_in *dst; /* for dummynet */ 378 int flags; /* for dummynet */ 379 380 struct ipfw_flow_id f_id; /* grabbed from IP header */ 381 u_int16_t divert_rule; /* divert cookie */ 382 u_int32_t retval; 383 }; 384 385 /* 386 * Function definitions. 387 */ 388 389 /* Firewall hooks */ 390 struct sockopt; 391 struct dn_flow_set; 392 393 void flush_pipe_ptrs(struct dn_flow_set *match); /* used by dummynet */ 394 395 typedef int ip_fw_chk_t (struct ip_fw_args *args); 396 typedef int ip_fw_ctl_t (struct sockopt *); 397 extern ip_fw_chk_t *ip_fw_chk_ptr; 398 extern ip_fw_ctl_t *ip_fw_ctl_ptr; 399 extern int fw_one_pass; 400 extern int fw_enable; 401 #define IPFW_LOADED (ip_fw_chk_ptr != NULL) 402 #endif /* _KERNEL */ 403 404 #endif /* _IPFW2_H */ 405