include/linux/netfilter_ipv4/ip_tables.h

   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/compiler.h>
  26 #include <linux/netfilter_ipv4.h>
  27
  28 #define IPT_FUNCTION_MAXNAMELEN 30
  29 #define IPT_TABLE_MAXNAMELEN 32
  30
  31 /* Yes, Virginia, you have to zero the padding. */
  32 struct ipt_ip {
  33         /* Source and destination IP addr */
  34         struct in_addr src, dst;
  35         /* Mask for src and dest IP addr */
  36         struct in_addr smsk, dmsk;
  37         char iniface[IFNAMSIZ], outiface[IFNAMSIZ];
  38         unsigned char iniface_mask[IFNAMSIZ], outiface_mask[IFNAMSIZ];
  39
  40         /* Protocol, 0 = ANY */
  41         u_int16_t proto;
  42
  43         /* Flags word */
  44         u_int8_t flags;
  45         /* Inverse flags */
  46         u_int8_t invflags;
  47 };
  48
  49 struct ipt_entry_match
  50 {
  51         union {
  52                 struct {
  53                         u_int16_t match_size;
  54
  55                         /* Used by userspace */
  56                         char name[IPT_FUNCTION_MAXNAMELEN];
  57                 } user;
  58                 struct {
  59                         u_int16_t match_size;
  60
  61                         /* Used inside the kernel */
  62                         struct ipt_match *match;
  63                 } kernel;
  64
  65                 /* Total length */
  66                 u_int16_t match_size;
  67         } u;
  68
  69         unsigned char data[0];
  70 };
  71
  72 struct ipt_entry_target
  73 {
  74         union {
  75                 struct {
  76                         u_int16_t target_size;
  77
  78                         /* Used by userspace */
  79                         char name[IPT_FUNCTION_MAXNAMELEN];
  80                 } user;
  81                 struct {
  82                         u_int16_t target_size;
  83
  84                         /* Used inside the kernel */
  85                         struct ipt_target *target;
  86                 } kernel;
  87
  88                 /* Total length */
  89                 u_int16_t target_size;
  90         } u;
  91
  92         unsigned char data[0];
  93 };
  94
  95 struct ipt_standard_target
  96 {
  97         struct ipt_entry_target target;
  98         int verdict;
  99 };
 100
 101 struct ipt_counters
 102 {
 103         u_int64_t pcnt, bcnt;                   /* Packet and byte counters */
 104 };
 105
 106 /* Values for "flag" field in struct ipt_ip (general ip structure). */
 107 #define IPT_F_FRAG              0x01    /* Set if rule is a fragment rule */
 108 #define IPT_F_MASK              0x01    /* All possible flag bits mask. */
 109
 110 /* Values for "inv" field in struct ipt_ip. */
 111 #define IPT_INV_VIA_IN          0x01    /* Invert the sense of IN IFACE. */
 112 #define IPT_INV_VIA_OUT         0x02    /* Invert the sense of OUT IFACE */
 113 #define IPT_INV_TOS             0x04    /* Invert the sense of TOS. */
 114 #define IPT_INV_SRCIP           0x08    /* Invert the sense of SRC IP. */
 115 #define IPT_INV_DSTIP           0x10    /* Invert the sense of DST OP. */
 116 #define IPT_INV_FRAG            0x20    /* Invert the sense of FRAG. */
 117 #define IPT_INV_PROTO           0x40    /* Invert the sense of PROTO. */
 118 #define IPT_INV_MASK            0x7F    /* All possible flag bits mask. */
 119
 120 /* This structure defines each of the firewall rules.  Consists of 3
 121    parts which are 1) general IP header stuff 2) match specific
 122    stuff 3) the target to perform if the rule matches */
 123 struct ipt_entry
 124 {
 125         struct ipt_ip ip;
 126
 127         /* Mark with fields that we care about. */
 128         unsigned int nfcache;
 129
 130         /* Size of ipt_entry + matches */
 131         u_int16_t target_offset;
 132         /* Size of ipt_entry + matches + target */
 133         u_int16_t next_offset;
 134
 135         /* Back pointer */
 136         unsigned int comefrom;
 137
 138         /* Packet and byte counters. */
 139         struct ipt_counters counters;
 140
 141         /* The matches (if any), then the target. */
 142         unsigned char elems[0];
 143 };
 144
 145 /*
 146  * New IP firewall options for [gs]etsockopt at the RAW IP level.
 147  * Unlike BSD Linux inherits IP options so you don't have to use a raw
 148  * socket for this. Instead we check rights in the calls. */
 149 #define IPT_BASE_CTL            64      /* base for firewall socket options */
 150
 151 #define IPT_SO_SET_REPLACE      (IPT_BASE_CTL)
 152 #define IPT_SO_SET_ADD_COUNTERS (IPT_BASE_CTL + 1)
 153 #define IPT_SO_SET_MAX          IPT_SO_SET_ADD_COUNTERS
 154
 155 #define IPT_SO_GET_INFO         (IPT_BASE_CTL)
 156 #define IPT_SO_GET_ENTRIES      (IPT_BASE_CTL + 1)
 157 #define IPT_SO_GET_MAX          IPT_SO_GET_ENTRIES
 158
 159 /* CONTINUE verdict for targets */
 160 #define IPT_CONTINUE 0xFFFFFFFF
 161
 162 /* For standard target */
 163 #define IPT_RETURN (-NF_MAX_VERDICT - 1)
 164
 165 /* TCP matching stuff */
 166 struct ipt_tcp
 167 {
 168         u_int16_t spts[2];                      /* Source port range. */
 169         u_int16_t dpts[2];                      /* Destination port range. */
 170         u_int8_t option;                        /* TCP Option iff non-zero*/
 171         u_int8_t flg_mask;                      /* TCP flags mask byte */
 172         u_int8_t flg_cmp;                       /* TCP flags compare byte */
 173         u_int8_t invflags;                      /* Inverse flags */
 174 };
 175
 176 /* Values for "inv" field in struct ipt_tcp. */
 177 #define IPT_TCP_INV_SRCPT       0x01    /* Invert the sense of source ports. */
 178 #define IPT_TCP_INV_DSTPT       0x02    /* Invert the sense of dest ports. */
 179 #define IPT_TCP_INV_FLAGS       0x04    /* Invert the sense of TCP flags. */
 180 #define IPT_TCP_INV_OPTION      0x08    /* Invert the sense of option test. */
 181 #define IPT_TCP_INV_MASK        0x0F    /* All possible flags. */
 182
 183 /* UDP matching stuff */
 184 struct ipt_udp
 185 {
 186         u_int16_t spts[2];                      /* Source port range. */
 187         u_int16_t dpts[2];                      /* Destination port range. */
 188         u_int8_t invflags;                      /* Inverse flags */
 189 };
 190
 191 /* Values for "invflags" field in struct ipt_udp. */
 192 #define IPT_UDP_INV_SRCPT       0x01    /* Invert the sense of source ports. */
 193 #define IPT_UDP_INV_DSTPT       0x02    /* Invert the sense of dest ports. */
 194 #define IPT_UDP_INV_MASK        0x03    /* All possible flags. */
 195
 196 /* ICMP matching stuff */
 197 struct ipt_icmp
 198 {
 199         u_int8_t type;                          /* type to match */
 200         u_int8_t code[2];                       /* range of code */
 201         u_int8_t invflags;                      /* Inverse flags */
 202 };
 203
 204 /* Values for "inv" field for struct ipt_icmp. */
 205 #define IPT_ICMP_INV    0x01    /* Invert the sense of type/code test */
 206
 207 /* The argument to IPT_SO_GET_INFO */
 208 struct ipt_getinfo
 209 {
 210         /* Which table: caller fills this in. */
 211         char name[IPT_TABLE_MAXNAMELEN];
 212
 213         /* Kernel fills these in. */
 214         /* Which hook entry points are valid: bitmask */
 215         unsigned int valid_hooks;
 216
 217         /* Hook entry points: one per netfilter hook. */
 218         unsigned int hook_entry[NF_IP_NUMHOOKS];
 219
 220         /* Underflow points. */
 221         unsigned int underflow[NF_IP_NUMHOOKS];
 222
 223         /* Number of entries */
 224         unsigned int num_entries;
 225
 226         /* Size of entries. */
 227         unsigned int size;
 228 };
 229
 230 /* The argument to IPT_SO_SET_REPLACE. */
 231 struct ipt_replace
 232 {
 233         /* Which table. */
 234         char name[IPT_TABLE_MAXNAMELEN];
 235
 236         /* Which hook entry points are valid: bitmask.  You can't
 237            change this. */
 238         unsigned int valid_hooks;
 239
 240         /* Number of entries */
 241         unsigned int num_entries;
 242
 243         /* Total size of new entries */
 244         unsigned int size;
 245
 246         /* Hook entry points. */
 247         unsigned int hook_entry[NF_IP_NUMHOOKS];
 248
 249         /* Underflow points. */
 250         unsigned int underflow[NF_IP_NUMHOOKS];
 251
 252         /* Information about old entries: */
 253         /* Number of counters (must be equal to current number of entries). */
 254         unsigned int num_counters;
 255         /* The old entries' counters. */
 256         struct ipt_counters __user *counters;
 257
 258         /* The entries (hang off end: not really an array). */
 259         struct ipt_entry entries[0];
 260 };
 261
 262 /* The argument to IPT_SO_ADD_COUNTERS. */
 263 struct ipt_counters_info
 264 {
 265         /* Which table. */
 266         char name[IPT_TABLE_MAXNAMELEN];
 267
 268         unsigned int num_counters;
 269
 270         /* The counters (actually `number' of these). */
 271         struct ipt_counters counters[0];
 272 };
 273
 274 /* The argument to IPT_SO_GET_ENTRIES. */
 275 struct ipt_get_entries
 276 {
 277         /* Which table: user fills this in. */
 278         char name[IPT_TABLE_MAXNAMELEN];
 279
 280         /* User fills this in: total entry size. */
 281         unsigned int size;
 282
 283         /* The entries. */
 284         struct ipt_entry entrytable[0];
 285 };
 286
 287 /* Standard return verdict, or do jump. */
 288 #define IPT_STANDARD_TARGET ""
 289 /* Error verdict. */
 290 #define IPT_ERROR_TARGET "ERROR"
 291
 292 /* Helper functions */
 293 static __inline__ struct ipt_entry_target *
 294 ipt_get_target(struct ipt_entry *e)
 295 {
 296         return (void *)e + e->target_offset;
 297 }
 298
 299 /* fn returns 0 to continue iteration */
 300 #define IPT_MATCH_ITERATE(e, fn, args...)       \
 301 ({                                              \
 302         unsigned int __i;                       \
 303         int __ret = 0;                          \
 304         struct ipt_entry_match *__match;        \
 305                                                 \
 306         for (__i = sizeof(struct ipt_entry);    \
 307              __i < (e)->target_offset;          \
 308              __i += __match->u.match_size) {    \
 309                 __match = (void *)(e) + __i;    \
 310                                                 \
 311                 __ret = fn(__match , ## args);  \
 312                 if (__ret != 0)                 \
 313                         break;                  \
 314         }                                       \
 315         __ret;                                  \
 316 })
 317
 318 /* fn returns 0 to continue iteration */
 319 #define IPT_ENTRY_ITERATE(entries, size, fn, args...)           \
 320 ({                                                              \
 321         unsigned int __i;                                       \
 322         int __ret = 0;                                          \
 323         struct ipt_entry *__entry;                              \
 324                                                                 \
 325         for (__i = 0; __i < (size); __i += __entry->next_offset) { \
 326                 __entry = (void *)(entries) + __i;              \
 327                                                                 \
 328                 __ret = fn(__entry , ## args);                  \
 329                 if (__ret != 0)                                 \
 330                         break;                                  \
 331         }                                                       \
 332         __ret;                                                  \
 333 })
 334
 335 /*
 336  *      Main firewall chains definitions and global var's definitions.
 337  */
 338 #ifdef __KERNEL__
 339
 340 #include <linux/init.h>
 341 extern void ipt_init(void) __init;
 342
 343 struct ipt_match
 344 {
 345         struct list_head list;
 346
 347         const char name[IPT_FUNCTION_MAXNAMELEN];
 348
 349         /* Return true or false: return FALSE and set *hotdrop = 1 to
 350            force immediate packet drop. */
 351         /* Arguments changed since 2.4, as this must now handle
 352            non-linear skbs, using skb_copy_bits and
 353            skb_ip_make_writable. */
 354         int (*match)(const struct sk_buff *skb,
 355                      const struct net_device *in,
 356                      const struct net_device *out,
 357                      const void *matchinfo,
 358                      int offset,
 359                      int *hotdrop);
 360
 361         /* Called when user tries to insert an entry of this type. */
 362         /* Should return true or false. */
 363         int (*checkentry)(const char *tablename,
 364                           const struct ipt_ip *ip,
 365                           void *matchinfo,
 366                           unsigned int matchinfosize,
 367                           unsigned int hook_mask);
 368
 369         /* Called when entry of this type deleted. */
 370         void (*destroy)(void *matchinfo, unsigned int matchinfosize);
 371
 372         /* Set this to THIS_MODULE. */
 373         struct module *me;
 374 };
 375
 376 /* Registration hooks for targets. */
 377 struct ipt_target
 378 {
 379         struct list_head list;
 380
 381         const char name[IPT_FUNCTION_MAXNAMELEN];
 382
 383         /* Called when user tries to insert an entry of this type:
 384            hook_mask is a bitmask of hooks from which it can be
 385            called. */
 386         /* Should return true or false. */
 387         int (*checkentry)(const char *tablename,
 388                           const struct ipt_entry *e,
 389                           void *targinfo,
 390                           unsigned int targinfosize,
 391                           unsigned int hook_mask);
 392
 393         /* Called when entry of this type deleted. */
 394         void (*destroy)(void *targinfo, unsigned int targinfosize);
 395
 396         /* Returns verdict.  Argument order changed since 2.4, as this
 397            must now handle non-linear skbs, using skb_copy_bits and
 398            skb_ip_make_writable. */
 399         unsigned int (*target)(struct sk_buff **pskb,
 400                                const struct net_device *in,
 401                                const struct net_device *out,
 402                                unsigned int hooknum,
 403                                const void *targinfo,
 404                                void *userdata);
 405
 406         /* Set this to THIS_MODULE. */
 407         struct module *me;
 408 };
 409
 410 extern struct ipt_target *
 411 ipt_find_target_lock(const char *name, int *error, struct semaphore *mutex);
 412 extern struct arpt_target *
 413 arpt_find_target_lock(const char *name, int *error, struct semaphore *mutex);
 414
 415 extern int ipt_register_target(struct ipt_target *target);
 416 extern void ipt_unregister_target(struct ipt_target *target);
 417
 418 extern int ipt_register_match(struct ipt_match *match);
 419 extern void ipt_unregister_match(struct ipt_match *match);
 420
 421 /* Furniture shopping... */
 422 struct ipt_table
 423 {
 424         struct list_head list;
 425
 426         /* A unique name... */
 427         char name[IPT_TABLE_MAXNAMELEN];
 428
 429         /* Seed table: copied in register_table */
 430         struct ipt_replace *table;
 431
 432         /* What hooks you will enter on */
 433         unsigned int valid_hooks;
 434
 435         /* Lock for the curtain */
 436         rwlock_t lock;
 437
 438         /* Man behind the curtain... */
 439         struct ipt_table_info *private;
 440
 441         /* Set to THIS_MODULE. */
 442         struct module *me;
 443 };
 444
 445 extern int ipt_register_table(struct ipt_table *table);
 446 extern void ipt_unregister_table(struct ipt_table *table);
 447 extern unsigned int ipt_do_table(struct sk_buff **pskb,
 448                                  unsigned int hook,
 449                                  const struct net_device *in,
 450                                  const struct net_device *out,
 451                                  struct ipt_table *table,
 452                                  void *userdata);
 453
 454 #define IPT_ALIGN(s) (((s) + (__alignof__(struct ipt_entry)-1)) & ~(__alignof__(struct ipt_entry)-1))
 455 #endif /*__KERNEL__*/
 456 #endif /* _IPTABLES_H */