1 /*
2 * 25-Jul-1998 Major changes to allow for ip chain table
3 *
4 * 3-Jan-2000 Named tables to allow packet selection for different uses.
5 */
6
7 /*
8 * Format of an IP firewall descriptor
9 *
10 * src, dst, src_mask, dst_mask are always stored in network byte order.
11 * flags are stored in host byte order (of course).
12 * Port numbers are stored in HOST byte order.
13 */
14
15 #ifndef _IPTABLES_H
16 #define _IPTABLES_H
17
18 #ifdef __KERNEL__
19 #include <linux/if.h>
20 #include <linux/types.h>
21 #include <linux/in.h>
22 #include <linux/ip.h>
23 #include <linux/skbuff.h>
24 #endif
25 #include <linux/netfilter_ipv4.h>
26
27 #define IPT_FUNCTION_MAXNAMELEN 30
28 #define IPT_TABLE_MAXNAMELEN 32
29
30 /* Yes, Virginia, you have to zero the padding. */
31 struct ipt_ip {
32 /* Source and destination IP addr */
33 struct in_addr src, dst;
34 /* Mask for src and dest IP addr */
35 struct in_addr smsk, dmsk;
36 char iniface[IFNAMSIZ], outiface[IFNAMSIZ];
37 unsigned char iniface_mask[IFNAMSIZ], outiface_mask[IFNAMSIZ];
38
39 /* Protocol, 0 = ANY */
40 u_int16_t proto;
41
42 /* Flags word */
43 u_int8_t flags;
44 /* Inverse flags */
45 u_int8_t invflags;
46 };
47
48 struct ipt_entry_match
49 {
50 union {
51 struct {
52 u_int16_t match_size;
53
54 /* Used by userspace */
55 char name[IPT_FUNCTION_MAXNAMELEN];
56 } user;
57 struct {
58 u_int16_t match_size;
59
60 /* Used inside the kernel */
61 struct ipt_match *match;
62 } kernel;
63
64 /* Total length */
65 u_int16_t match_size;
66 } u;
67
68 unsigned char data[0];
69 };
70
71 struct ipt_entry_target
72 {
73 union {
74 struct {
75 u_int16_t target_size;
76
77 /* Used by userspace */
78 char name[IPT_FUNCTION_MAXNAMELEN];
79 } user;
80 struct {
81 u_int16_t target_size;
82
83 /* Used inside the kernel */
84 struct ipt_target *target;
85 } kernel;
86
87 /* Total length */
88 u_int16_t target_size;
89 } u;
90
91 unsigned char data[0];
92 };
93
94 struct ipt_standard_target
95 {
96 struct ipt_entry_target target;
97 int verdict;
98 };
99
100 struct ipt_counters
101 {
102 u_int64_t pcnt, bcnt; /* Packet and byte counters */
103 };
104
105 /* Values for "flag" field in struct ipt_ip (general ip structure). */
106 #define IPT_F_FRAG 0x01 /* Set if rule is a fragment rule */
107 #define IPT_F_MASK 0x01 /* All possible flag bits mask. */
108
109 /* Values for "inv" field in struct ipt_ip. */
110 #define IPT_INV_VIA_IN 0x01 /* Invert the sense of IN IFACE. */
111 #define IPT_INV_VIA_OUT 0x02 /* Invert the sense of OUT IFACE */
112 #define IPT_INV_TOS 0x04 /* Invert the sense of TOS. */
113 #define IPT_INV_SRCIP 0x08 /* Invert the sense of SRC IP. */
114 #define IPT_INV_DSTIP 0x10 /* Invert the sense of DST OP. */
115 #define IPT_INV_FRAG 0x20 /* Invert the sense of FRAG. */
116 #define IPT_INV_PROTO 0x40 /* Invert the sense of PROTO. */
117 #define IPT_INV_MASK 0x7F /* All possible flag bits mask. */
118
119 /* This structure defines each of the firewall rules. Consists of 3
120 parts which are 1) general IP header stuff 2) match specific
121 stuff 3) the target to perform if the rule matches */
122 struct ipt_entry
123 {
124 struct ipt_ip ip;
125
126 /* Mark with fields that we care about. */
127 unsigned int nfcache;
128
129 /* Size of ipt_entry + matches */
130 u_int16_t target_offset;
131 /* Size of ipt_entry + matches + target */
132 u_int16_t next_offset;
133
134 /* Back pointer */
135 unsigned int comefrom;
136
137 /* Packet and byte counters. */
138 struct ipt_counters counters;
139
140 /* The matches (if any), then the target. */
141 unsigned char elems[0];
142 };
143
144 /*
145 * New IP firewall options for [gs]etsockopt at the RAW IP level.
146 * Unlike BSD Linux inherits IP options so you don't have to use a raw
147 * socket for this. Instead we check rights in the calls. */
148 #define IPT_BASE_CTL 64 /* base for firewall socket options */
149
150 #define IPT_SO_SET_REPLACE (IPT_BASE_CTL)
151 #define IPT_SO_SET_ADD_COUNTERS (IPT_BASE_CTL + 1)
152 #define IPT_SO_SET_MAX IPT_SO_SET_ADD_COUNTERS
153
154 #define IPT_SO_GET_INFO (IPT_BASE_CTL)
155 #define IPT_SO_GET_ENTRIES (IPT_BASE_CTL + 1)
156 #define IPT_SO_GET_MAX IPT_SO_GET_ENTRIES
157
158 /* CONTINUE verdict for targets */
159 #define IPT_CONTINUE 0xFFFFFFFF
160
161 /* For standard target */
162 #define IPT_RETURN (-NF_MAX_VERDICT - 1)
163
164 /* TCP matching stuff */
165 struct ipt_tcp
166 {
167 u_int16_t spts[2]; /* Source port range. */
168 u_int16_t dpts[2]; /* Destination port range. */
169 u_int8_t option; /* TCP Option iff non-zero*/
170 u_int8_t flg_mask; /* TCP flags mask byte */
171 u_int8_t flg_cmp; /* TCP flags compare byte */
172 u_int8_t invflags; /* Inverse flags */
173 };
174
175 /* Values for "inv" field in struct ipt_tcp. */
176 #define IPT_TCP_INV_SRCPT 0x01 /* Invert the sense of source ports. */
177 #define IPT_TCP_INV_DSTPT 0x02 /* Invert the sense of dest ports. */
178 #define IPT_TCP_INV_FLAGS 0x04 /* Invert the sense of TCP flags. */
179 #define IPT_TCP_INV_OPTION 0x08 /* Invert the sense of option test. */
180 #define IPT_TCP_INV_MASK 0x0F /* All possible flags. */
181
182 /* UDP matching stuff */
183 struct ipt_udp
184 {
185 u_int16_t spts[2]; /* Source port range. */
186 u_int16_t dpts[2]; /* Destination port range. */
187 u_int8_t invflags; /* Inverse flags */
188 };
189
190 /* Values for "invflags" field in struct ipt_udp. */
191 #define IPT_UDP_INV_SRCPT 0x01 /* Invert the sense of source ports. */
192 #define IPT_UDP_INV_DSTPT 0x02 /* Invert the sense of dest ports. */
193 #define IPT_UDP_INV_MASK 0x03 /* All possible flags. */
194
195 /* ICMP matching stuff */
196 struct ipt_icmp
197 {
198 u_int8_t type; /* type to match */
199 u_int8_t code[2]; /* range of code */
200 u_int8_t invflags; /* Inverse flags */
201 };
202
203 /* Values for "inv" field for struct ipt_icmp. */
204 #define IPT_ICMP_INV 0x01 /* Invert the sense of type/code test */
205
206 /* The argument to IPT_SO_GET_INFO */
207 struct ipt_getinfo
208 {
209 /* Which table: caller fills this in. */
210 char name[IPT_TABLE_MAXNAMELEN];
211
212 /* Kernel fills these in. */
213 /* Which hook entry points are valid: bitmask */
214 unsigned int valid_hooks;
215
216 /* Hook entry points: one per netfilter hook. */
217 unsigned int hook_entry[NF_IP_NUMHOOKS];
218
219 /* Underflow points. */
220 unsigned int underflow[NF_IP_NUMHOOKS];
221
222 /* Number of entries */
223 unsigned int num_entries;
224
225 /* Size of entries. */
226 unsigned int size;
227 };
228
229 /* The argument to IPT_SO_SET_REPLACE. */
230 struct ipt_replace
231 {
232 /* Which table. */
233 char name[IPT_TABLE_MAXNAMELEN];
234
235 /* Which hook entry points are valid: bitmask. You can't
236 change this. */
237 unsigned int valid_hooks;
238
239 /* Number of entries */
240 unsigned int num_entries;
241
242 /* Total size of new entries */
243 unsigned int size;
244
245 /* Hook entry points. */
246 unsigned int hook_entry[NF_IP_NUMHOOKS];
247
248 /* Underflow points. */
249 unsigned int underflow[NF_IP_NUMHOOKS];
250
251 /* Information about old entries: */
252 /* Number of counters (must be equal to current number of entries). */
253 unsigned int num_counters;
254 /* The old entries' counters. */
255 struct ipt_counters *counters;
256
257 /* The entries (hang off end: not really an array). */
258 struct ipt_entry entries[0];
259 };
260
261 /* The argument to IPT_SO_ADD_COUNTERS. */
262 struct ipt_counters_info
263 {
264 /* Which table. */
265 char name[IPT_TABLE_MAXNAMELEN];
266
267 unsigned int num_counters;
268
269 /* The counters (actually `number' of these). */
270 struct ipt_counters counters[0];
271 };
272
273 /* The argument to IPT_SO_GET_ENTRIES. */
274 struct ipt_get_entries
275 {
276 /* Which table: user fills this in. */
277 char name[IPT_TABLE_MAXNAMELEN];
278
279 /* User fills this in: total entry size. */
280 unsigned int size;
281
282 /* The entries. */
283 struct ipt_entry entrytable[0];
284 };
285
286 /* Standard return verdict, or do jump. */
287 #define IPT_STANDARD_TARGET ""
288 /* Error verdict. */
289 #define IPT_ERROR_TARGET "ERROR"
290
291 /* Helper functions */
292 static __inline__ struct ipt_entry_target *
ipt_get_target(struct ipt_entry * e)293 ipt_get_target(struct ipt_entry *e)
294 {
295 return (void *)e + e->target_offset;
296 }
297
298 /* fn returns 0 to continue iteration */
299 #define IPT_MATCH_ITERATE(e, fn, args...) \
300 ({ \
301 unsigned int __i; \
302 int __ret = 0; \
303 struct ipt_entry_match *__match; \
304 \
305 for (__i = sizeof(struct ipt_entry); \
306 __i < (e)->target_offset; \
307 __i += __match->u.match_size) { \
308 __match = (void *)(e) + __i; \
309 \
310 __ret = fn(__match , ## args); \
311 if (__ret != 0) \
312 break; \
313 } \
314 __ret; \
315 })
316
317 /* fn returns 0 to continue iteration */
318 #define IPT_ENTRY_ITERATE(entries, size, fn, args...) \
319 ({ \
320 unsigned int __i; \
321 int __ret = 0; \
322 struct ipt_entry *__entry; \
323 \
324 for (__i = 0; __i < (size); __i += __entry->next_offset) { \
325 __entry = (void *)(entries) + __i; \
326 \
327 __ret = fn(__entry , ## args); \
328 if (__ret != 0) \
329 break; \
330 } \
331 __ret; \
332 })
333
334 /*
335 * Main firewall chains definitions and global var's definitions.
336 */
337 #ifdef __KERNEL__
338
339 #include <linux/init.h>
340 extern void ipt_init(void) __init;
341
342 struct ipt_match
343 {
344 struct list_head list;
345
346 const char name[IPT_FUNCTION_MAXNAMELEN];
347
348 /* Return true or false: return FALSE and set *hotdrop = 1 to
349 force immediate packet drop. */
350 int (*match)(const struct sk_buff *skb,
351 const struct net_device *in,
352 const struct net_device *out,
353 const void *matchinfo,
354 int offset,
355 const void *hdr,
356 u_int16_t datalen,
357 int *hotdrop);
358
359 /* Called when user tries to insert an entry of this type. */
360 /* Should return true or false. */
361 int (*checkentry)(const char *tablename,
362 const struct ipt_ip *ip,
363 void *matchinfo,
364 unsigned int matchinfosize,
365 unsigned int hook_mask);
366
367 /* Called when entry of this type deleted. */
368 void (*destroy)(void *matchinfo, unsigned int matchinfosize);
369
370 /* Set this to THIS_MODULE if you are a module, otherwise NULL */
371 struct module *me;
372 };
373
374 /* Registration hooks for targets. */
375 struct ipt_target
376 {
377 struct list_head list;
378
379 const char name[IPT_FUNCTION_MAXNAMELEN];
380
381 /* Returns verdict. */
382 unsigned int (*target)(struct sk_buff **pskb,
383 unsigned int hooknum,
384 const struct net_device *in,
385 const struct net_device *out,
386 const void *targinfo,
387 void *userdata);
388
389 /* Called when user tries to insert an entry of this type:
390 hook_mask is a bitmask of hooks from which it can be
391 called. */
392 /* Should return true or false. */
393 int (*checkentry)(const char *tablename,
394 const struct ipt_entry *e,
395 void *targinfo,
396 unsigned int targinfosize,
397 unsigned int hook_mask);
398
399 /* Called when entry of this type deleted. */
400 void (*destroy)(void *targinfo, unsigned int targinfosize);
401
402 /* Set this to THIS_MODULE if you are a module, otherwise NULL */
403 struct module *me;
404 };
405
406 extern struct ipt_target *
407 ipt_find_target_lock(const char *name, int *error, struct semaphore *mutex);
408 extern struct arpt_target *
409 arpt_find_target_lock(const char *name, int *error, struct semaphore *mutex);
410
411 extern int ipt_register_target(struct ipt_target *target);
412 extern void ipt_unregister_target(struct ipt_target *target);
413
414 extern int ipt_register_match(struct ipt_match *match);
415 extern void ipt_unregister_match(struct ipt_match *match);
416
417 /* Furniture shopping... */
418 struct ipt_table
419 {
420 struct list_head list;
421
422 /* A unique name... */
423 char name[IPT_TABLE_MAXNAMELEN];
424
425 /* Seed table: copied in register_table */
426 struct ipt_replace *table;
427
428 /* What hooks you will enter on */
429 unsigned int valid_hooks;
430
431 /* Lock for the curtain */
432 rwlock_t lock;
433
434 /* Man behind the curtain... */
435 struct ipt_table_info *private;
436
437 /* Set this to THIS_MODULE if you are a module, otherwise NULL */
438 struct module *me;
439 };
440
441 extern int ipt_register_table(struct ipt_table *table);
442 extern void ipt_unregister_table(struct ipt_table *table);
443 extern unsigned int ipt_do_table(struct sk_buff **pskb,
444 unsigned int hook,
445 const struct net_device *in,
446 const struct net_device *out,
447 struct ipt_table *table,
448 void *userdata);
449
450 #define IPT_ALIGN(s) (((s) + (__alignof__(struct ipt_entry)-1)) & ~(__alignof__(struct ipt_entry)-1))
451 #endif /*__KERNEL__*/
452 #endif /* _IPTABLES_H */
453