include/linux/netfilter/x_tables.h

   1 #ifndef _X_TABLES_H
   2 #define _X_TABLES_H
   3
   4 #include <linux/types.h>
   5
   6 #define XT_FUNCTION_MAXNAMELEN 30
   7 #define XT_TABLE_MAXNAMELEN 32
   8
   9 struct xt_entry_match {
  10         union {
  11                 struct {
  12                         __u16 match_size;
  13
  14                         /* Used by userspace */
  15                         char name[XT_FUNCTION_MAXNAMELEN-1];
  16
  17                         __u8 revision;
  18                 } user;
  19                 struct {
  20                         __u16 match_size;
  21
  22                         /* Used inside the kernel */
  23                         struct xt_match *match;
  24                 } kernel;
  25
  26                 /* Total length */
  27                 __u16 match_size;
  28         } u;
  29
  30         unsigned char data[0];
  31 };
  32
  33 struct xt_entry_target {
  34         union {
  35                 struct {
  36                         __u16 target_size;
  37
  38                         /* Used by userspace */
  39                         char name[XT_FUNCTION_MAXNAMELEN-1];
  40
  41                         __u8 revision;
  42                 } user;
  43                 struct {
  44                         __u16 target_size;
  45
  46                         /* Used inside the kernel */
  47                         struct xt_target *target;
  48                 } kernel;
  49
  50                 /* Total length */
  51                 __u16 target_size;
  52         } u;
  53
  54         unsigned char data[0];
  55 };
  56
  57 #define XT_TARGET_INIT(__name, __size)                                         \
  58 {                                                                              \
  59         .target.u.user = {                                                     \
  60                 .target_size    = XT_ALIGN(__size),                            \
  61                 .name           = __name,                                      \
  62         },                                                                     \
  63 }
  64
  65 struct xt_standard_target {
  66         struct xt_entry_target target;
  67         int verdict;
  68 };
  69
  70 /* The argument to IPT_SO_GET_REVISION_*.  Returns highest revision
  71  * kernel supports, if >= revision. */
  72 struct xt_get_revision {
  73         char name[XT_FUNCTION_MAXNAMELEN-1];
  74
  75         __u8 revision;
  76 };
  77
  78 /* CONTINUE verdict for targets */
  79 #define XT_CONTINUE 0xFFFFFFFF
  80
  81 /* For standard target */
  82 #define XT_RETURN (-NF_REPEAT - 1)
  83
  84 /* this is a dummy structure to find out the alignment requirement for a struct
  85  * containing all the fundamental data types that are used in ipt_entry,
  86  * ip6t_entry and arpt_entry.  This sucks, and it is a hack.  It will be my
  87  * personal pleasure to remove it -HW
  88  */
  89 struct _xt_align {
  90         __u8 u8;
  91         __u16 u16;
  92         __u32 u32;
  93         __u64 u64;
  94 };
  95
  96 #define XT_ALIGN(s) ALIGN((s), __alignof__(struct _xt_align))
  97
  98 /* Standard return verdict, or do jump. */
  99 #define XT_STANDARD_TARGET ""
 100 /* Error verdict. */
 101 #define XT_ERROR_TARGET "ERROR"
 102
 103 #define SET_COUNTER(c,b,p) do { (c).bcnt = (b); (c).pcnt = (p); } while(0)
 104 #define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)
 105
 106 struct xt_counters {
 107         __u64 pcnt, bcnt;                       /* Packet and byte counters */
 108 };
 109
 110 /* The argument to IPT_SO_ADD_COUNTERS. */
 111 struct xt_counters_info {
 112         /* Which table. */
 113         char name[XT_TABLE_MAXNAMELEN];
 114
 115         unsigned int num_counters;
 116
 117         /* The counters (actually `number' of these). */
 118         struct xt_counters counters[0];
 119 };
 120
 121 #define XT_INV_PROTO            0x40    /* Invert the sense of PROTO. */
 122
 123 #ifndef __KERNEL__
 124 /* fn returns 0 to continue iteration */
 125 #define XT_MATCH_ITERATE(type, e, fn, args...)                  \
 126 ({                                                              \
 127         unsigned int __i;                                       \
 128         int __ret = 0;                                          \
 129         struct xt_entry_match *__m;                             \
 130                                                                 \
 131         for (__i = sizeof(type);                                \
 132              __i < (e)->target_offset;                          \
 133              __i += __m->u.match_size) {                        \
 134                 __m = (void *)e + __i;                          \
 135                                                                 \
 136                 __ret = fn(__m , ## args);                      \
 137                 if (__ret != 0)                                 \
 138                         break;                                  \
 139         }                                                       \
 140         __ret;                                                  \
 141 })
 142
 143 /* fn returns 0 to continue iteration */
 144 #define XT_ENTRY_ITERATE_CONTINUE(type, entries, size, n, fn, args...) \
 145 ({                                                              \
 146         unsigned int __i, __n;                                  \
 147         int __ret = 0;                                          \
 148         type *__entry;                                          \
 149                                                                 \
 150         for (__i = 0, __n = 0; __i < (size);                    \
 151              __i += __entry->next_offset, __n++) {              \
 152                 __entry = (void *)(entries) + __i;              \
 153                 if (__n < n)                                    \
 154                         continue;                               \
 155                                                                 \
 156                 __ret = fn(__entry , ## args);                  \
 157                 if (__ret != 0)                                 \
 158                         break;                                  \
 159         }                                                       \
 160         __ret;                                                  \
 161 })
 162
 163 /* fn returns 0 to continue iteration */
 164 #define XT_ENTRY_ITERATE(type, entries, size, fn, args...) \
 165         XT_ENTRY_ITERATE_CONTINUE(type, entries, size, 0, fn, args)
 166
 167 #endif /* !__KERNEL__ */
 168
 169 /* pos is normally a struct ipt_entry/ip6t_entry/etc. */
 170 #define xt_entry_foreach(pos, ehead, esize) \
 171         for ((pos) = (typeof(pos))(ehead); \
 172              (pos) < (typeof(pos))((char *)(ehead) + (esize)); \
 173              (pos) = (typeof(pos))((char *)(pos) + (pos)->next_offset))
 174
 175 /* can only be xt_entry_match, so no use of typeof here */
 176 #define xt_ematch_foreach(pos, entry) \
 177         for ((pos) = (struct xt_entry_match *)entry->elems; \
 178              (pos) < (struct xt_entry_match *)((char *)(entry) + \
 179                      (entry)->target_offset); \
 180              (pos) = (struct xt_entry_match *)((char *)(pos) + \
 181                      (pos)->u.match_size))
 182
 183 #ifdef __KERNEL__
 184
 185 #include <linux/netdevice.h>
 186
 187 /**
 188  * struct xt_match_param - parameters for match extensions' match functions
 189  *
 190  * @in:         input netdevice
 191  * @out:        output netdevice
 192  * @match:      struct xt_match through which this function was invoked
 193  * @matchinfo:  per-match data
 194  * @fragoff:    packet is a fragment, this is the data offset
 195  * @thoff:      position of transport header relative to skb->data
 196  * @hook:       hook number given packet came from
 197  * @family:     Actual NFPROTO_* through which the function is invoked
 198  *              (helpful when match->family == NFPROTO_UNSPEC)
 199  * @hotdrop:    drop packet if we had inspection problems
 200  */
 201 struct xt_match_param {
 202         const struct net_device *in, *out;
 203         const struct xt_match *match;
 204         const void *matchinfo;
 205         int fragoff;
 206         unsigned int thoff;
 207         unsigned int hooknum;
 208         u_int8_t family;
 209         bool *hotdrop;
 210 };
 211
 212 /**
 213  * struct xt_mtchk_param - parameters for match extensions'
 214  * checkentry functions
 215  *
 216  * @table:      table the rule is tried to be inserted into
 217  * @entryinfo:  the family-specific rule data
 218  *              (struct ipt_ip, ip6t_ip, ebt_entry)
 219  * @match:      struct xt_match through which this function was invoked
 220  * @matchinfo:  per-match data
 221  * @hook_mask:  via which hooks the new rule is reachable
 222  */
 223 struct xt_mtchk_param {
 224         struct net *net;
 225         const char *table;
 226         const void *entryinfo;
 227         const struct xt_match *match;
 228         void *matchinfo;
 229         unsigned int hook_mask;
 230         u_int8_t family;
 231 };
 232
 233 /* Match destructor parameters */
 234 struct xt_mtdtor_param {
 235         struct net *net;
 236         const struct xt_match *match;
 237         void *matchinfo;
 238         u_int8_t family;
 239 };
 240
 241 /**
 242  * struct xt_target_param - parameters for target extensions' target functions
 243  *
 244  * @hooknum:    hook through which this target was invoked
 245  * @target:     struct xt_target through which this function was invoked
 246  * @targinfo:   per-target data
 247  *
 248  * Other fields see above.
 249  */
 250 struct xt_target_param {
 251         const struct net_device *in, *out;
 252         const struct xt_target *target;
 253         const void *targinfo;
 254         unsigned int hooknum;
 255         u_int8_t family;
 256 };
 257
 258 /**
 259  * struct xt_tgchk_param - parameters for target extensions'
 260  * checkentry functions
 261  *
 262  * @entryinfo:  the family-specific rule data
 263  *              (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
 264  *
 265  * Other fields see above.
 266  */
 267 struct xt_tgchk_param {
 268         struct net *net;
 269         const char *table;
 270         const void *entryinfo;
 271         const struct xt_target *target;
 272         void *targinfo;
 273         unsigned int hook_mask;
 274         u_int8_t family;
 275 };
 276
 277 /* Target destructor parameters */
 278 struct xt_tgdtor_param {
 279         struct net *net;
 280         const struct xt_target *target;
 281         void *targinfo;
 282         u_int8_t family;
 283 };
 284
 285 struct xt_match {
 286         struct list_head list;
 287
 288         const char name[XT_FUNCTION_MAXNAMELEN-1];
 289         u_int8_t revision;
 290
 291         /* Return true or false: return FALSE and set *hotdrop = 1 to
 292            force immediate packet drop. */
 293         /* Arguments changed since 2.6.9, as this must now handle
 294            non-linear skb, using skb_header_pointer and
 295            skb_ip_make_writable. */
 296         bool (*match)(const struct sk_buff *skb,
 297                       const struct xt_match_param *);
 298
 299         /* Called when user tries to insert an entry of this type. */
 300         bool (*checkentry)(const struct xt_mtchk_param *);
 301
 302         /* Called when entry of this type deleted. */
 303         void (*destroy)(const struct xt_mtdtor_param *);
 304 #ifdef CONFIG_COMPAT
 305         /* Called when userspace align differs from kernel space one */
 306         void (*compat_from_user)(void *dst, const void *src);
 307         int (*compat_to_user)(void __user *dst, const void *src);
 308 #endif
 309         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 310         struct module *me;
 311
 312         /* Free to use by each match */
 313         unsigned long data;
 314
 315         const char *table;
 316         unsigned int matchsize;
 317 #ifdef CONFIG_COMPAT
 318         unsigned int compatsize;
 319 #endif
 320         unsigned int hooks;
 321         unsigned short proto;
 322
 323         unsigned short family;
 324 };
 325
 326 /* Registration hooks for targets. */
 327 struct xt_target {
 328         struct list_head list;
 329
 330         const char name[XT_FUNCTION_MAXNAMELEN-1];
 331
 332         /* Returns verdict. Argument order changed since 2.6.9, as this
 333            must now handle non-linear skbs, using skb_copy_bits and
 334            skb_ip_make_writable. */
 335         unsigned int (*target)(struct sk_buff *skb,
 336                                const struct xt_target_param *);
 337
 338         /* Called when user tries to insert an entry of this type:
 339            hook_mask is a bitmask of hooks from which it can be
 340            called. */
 341         /* Should return true or false. */
 342         bool (*checkentry)(const struct xt_tgchk_param *);
 343
 344         /* Called when entry of this type deleted. */
 345         void (*destroy)(const struct xt_tgdtor_param *);
 346 #ifdef CONFIG_COMPAT
 347         /* Called when userspace align differs from kernel space one */
 348         void (*compat_from_user)(void *dst, const void *src);
 349         int (*compat_to_user)(void __user *dst, const void *src);
 350 #endif
 351         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 352         struct module *me;
 353
 354         const char *table;
 355         unsigned int targetsize;
 356 #ifdef CONFIG_COMPAT
 357         unsigned int compatsize;
 358 #endif
 359         unsigned int hooks;
 360         unsigned short proto;
 361
 362         unsigned short family;
 363         u_int8_t revision;
 364 };
 365
 366 /* Furniture shopping... */
 367 struct xt_table {
 368         struct list_head list;
 369
 370         /* What hooks you will enter on */
 371         unsigned int valid_hooks;
 372
 373         /* Man behind the curtain... */
 374         struct xt_table_info *private;
 375
 376         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 377         struct module *me;
 378
 379         u_int8_t af;            /* address/protocol family */
 380         int priority;           /* hook order */
 381
 382         /* A unique name... */
 383         const char name[XT_TABLE_MAXNAMELEN];
 384 };
 385
 386 #include <linux/netfilter_ipv4.h>
 387
 388 /* The table itself */
 389 struct xt_table_info {
 390         /* Size per table */
 391         unsigned int size;
 392         /* Number of entries: FIXME. --RR */
 393         unsigned int number;
 394         /* Initial number of entries. Needed for module usage count */
 395         unsigned int initial_entries;
 396
 397         /* Entry points and underflows */
 398         unsigned int hook_entry[NF_INET_NUMHOOKS];
 399         unsigned int underflow[NF_INET_NUMHOOKS];
 400
 401         /* ipt_entry tables: one per CPU */
 402         /* Note : this field MUST be the last one, see XT_TABLE_INFO_SZ */
 403         void *entries[1];
 404 };
 405
 406 #define XT_TABLE_INFO_SZ (offsetof(struct xt_table_info, entries) \
 407                           + nr_cpu_ids * sizeof(char *))
 408 extern int xt_register_target(struct xt_target *target);
 409 extern void xt_unregister_target(struct xt_target *target);
 410 extern int xt_register_targets(struct xt_target *target, unsigned int n);
 411 extern void xt_unregister_targets(struct xt_target *target, unsigned int n);
 412
 413 extern int xt_register_match(struct xt_match *target);
 414 extern void xt_unregister_match(struct xt_match *target);
 415 extern int xt_register_matches(struct xt_match *match, unsigned int n);
 416 extern void xt_unregister_matches(struct xt_match *match, unsigned int n);
 417
 418 extern int xt_check_match(struct xt_mtchk_param *,
 419                           unsigned int size, u_int8_t proto, bool inv_proto);
 420 extern int xt_check_target(struct xt_tgchk_param *,
 421                            unsigned int size, u_int8_t proto, bool inv_proto);
 422
 423 extern struct xt_table *xt_register_table(struct net *net,
 424                                           const struct xt_table *table,
 425                                           struct xt_table_info *bootstrap,
 426                                           struct xt_table_info *newinfo);
 427 extern void *xt_unregister_table(struct xt_table *table);
 428
 429 extern struct xt_table_info *xt_replace_table(struct xt_table *table,
 430                                               unsigned int num_counters,
 431                                               struct xt_table_info *newinfo,
 432                                               int *error);
 433
 434 extern struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
 435 extern struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
 436 extern struct xt_target *xt_request_find_target(u8 af, const char *name,
 437                                                 u8 revision);
 438 extern int xt_find_revision(u8 af, const char *name, u8 revision,
 439                             int target, int *err);
 440
 441 extern struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 442                                            const char *name);
 443 extern void xt_table_unlock(struct xt_table *t);
 444
 445 extern int xt_proto_init(struct net *net, u_int8_t af);
 446 extern void xt_proto_fini(struct net *net, u_int8_t af);
 447
 448 extern struct xt_table_info *xt_alloc_table_info(unsigned int size);
 449 extern void xt_free_table_info(struct xt_table_info *info);
 450
 451 /*
 452  * Per-CPU spinlock associated with per-cpu table entries, and
 453  * with a counter for the "reading" side that allows a recursive
 454  * reader to avoid taking the lock and deadlocking.
 455  *
 456  * "reading" is used by ip/arp/ip6 tables rule processing which runs per-cpu.
 457  * It needs to ensure that the rules are not being changed while the packet
 458  * is being processed. In some cases, the read lock will be acquired
 459  * twice on the same CPU; this is okay because of the count.
 460  *
 461  * "writing" is used when reading counters.
 462  *  During replace any readers that are using the old tables have to complete
 463  *  before freeing the old table. This is handled by the write locking
 464  *  necessary for reading the counters.
 465  */
 466 struct xt_info_lock {
 467         spinlock_t lock;
 468         unsigned char readers;
 469 };
 470 DECLARE_PER_CPU(struct xt_info_lock, xt_info_locks);
 471
 472 /*
 473  * Note: we need to ensure that preemption is disabled before acquiring
 474  * the per-cpu-variable, so we do it as a two step process rather than
 475  * using "spin_lock_bh()".
 476  *
 477  * We _also_ need to disable bottom half processing before updating our
 478  * nesting count, to make sure that the only kind of re-entrancy is this
 479  * code being called by itself: since the count+lock is not an atomic
 480  * operation, we can allow no races.
 481  *
 482  * _Only_ that special combination of being per-cpu and never getting
 483  * re-entered asynchronously means that the count is safe.
 484  */
 485 static inline void xt_info_rdlock_bh(void)
 486 {
 487         struct xt_info_lock *lock;
 488
 489         local_bh_disable();
 490         lock = &__get_cpu_var(xt_info_locks);
 491         if (likely(!lock->readers++))
 492                 spin_lock(&lock->lock);
 493 }
 494
 495 static inline void xt_info_rdunlock_bh(void)
 496 {
 497         struct xt_info_lock *lock = &__get_cpu_var(xt_info_locks);
 498
 499         if (likely(!--lock->readers))
 500                 spin_unlock(&lock->lock);
 501         local_bh_enable();
 502 }
 503
 504 /*
 505  * The "writer" side needs to get exclusive access to the lock,
 506  * regardless of readers.  This must be called with bottom half
 507  * processing (and thus also preemption) disabled.
 508  */
 509 static inline void xt_info_wrlock(unsigned int cpu)
 510 {
 511         spin_lock(&per_cpu(xt_info_locks, cpu).lock);
 512 }
 513
 514 static inline void xt_info_wrunlock(unsigned int cpu)
 515 {
 516         spin_unlock(&per_cpu(xt_info_locks, cpu).lock);
 517 }
 518
 519 /*
 520  * This helper is performance critical and must be inlined
 521  */
 522 static inline unsigned long ifname_compare_aligned(const char *_a,
 523                                                    const char *_b,
 524                                                    const char *_mask)
 525 {
 526         const unsigned long *a = (const unsigned long *)_a;
 527         const unsigned long *b = (const unsigned long *)_b;
 528         const unsigned long *mask = (const unsigned long *)_mask;
 529         unsigned long ret;
 530
 531         ret = (a[0] ^ b[0]) & mask[0];
 532         if (IFNAMSIZ > sizeof(unsigned long))
 533                 ret |= (a[1] ^ b[1]) & mask[1];
 534         if (IFNAMSIZ > 2 * sizeof(unsigned long))
 535                 ret |= (a[2] ^ b[2]) & mask[2];
 536         if (IFNAMSIZ > 3 * sizeof(unsigned long))
 537                 ret |= (a[3] ^ b[3]) & mask[3];
 538         BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
 539         return ret;
 540 }
 541
 542 extern struct nf_hook_ops *xt_hook_link(const struct xt_table *, nf_hookfn *);
 543 extern void xt_hook_unlink(const struct xt_table *, struct nf_hook_ops *);
 544
 545 #ifdef CONFIG_COMPAT
 546 #include <net/compat.h>
 547
 548 struct compat_xt_entry_match {
 549         union {
 550                 struct {
 551                         u_int16_t match_size;
 552                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 553                         u_int8_t revision;
 554                 } user;
 555                 struct {
 556                         u_int16_t match_size;
 557                         compat_uptr_t match;
 558                 } kernel;
 559                 u_int16_t match_size;
 560         } u;
 561         unsigned char data[0];
 562 };
 563
 564 struct compat_xt_entry_target {
 565         union {
 566                 struct {
 567                         u_int16_t target_size;
 568                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 569                         u_int8_t revision;
 570                 } user;
 571                 struct {
 572                         u_int16_t target_size;
 573                         compat_uptr_t target;
 574                 } kernel;
 575                 u_int16_t target_size;
 576         } u;
 577         unsigned char data[0];
 578 };
 579
 580 /* FIXME: this works only on 32 bit tasks
 581  * need to change whole approach in order to calculate align as function of
 582  * current task alignment */
 583
 584 struct compat_xt_counters {
 585         compat_u64 pcnt, bcnt;                  /* Packet and byte counters */
 586 };
 587
 588 struct compat_xt_counters_info {
 589         char name[XT_TABLE_MAXNAMELEN];
 590         compat_uint_t num_counters;
 591         struct compat_xt_counters counters[0];
 592 };
 593
 594 struct _compat_xt_align {
 595         __u8 u8;
 596         __u16 u16;
 597         __u32 u32;
 598         compat_u64 u64;
 599 };
 600
 601 #define COMPAT_XT_ALIGN(s) ALIGN((s), __alignof__(struct _compat_xt_align))
 602
 603 extern void xt_compat_lock(u_int8_t af);
 604 extern void xt_compat_unlock(u_int8_t af);
 605
 606 extern int xt_compat_add_offset(u_int8_t af, unsigned int offset, short delta);
 607 extern void xt_compat_flush_offsets(u_int8_t af);
 608 extern int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 609
 610 extern int xt_compat_match_offset(const struct xt_match *match);
 611 extern int xt_compat_match_from_user(struct xt_entry_match *m,
 612                                      void **dstptr, unsigned int *size);
 613 extern int xt_compat_match_to_user(const struct xt_entry_match *m,
 614                                    void __user **dstptr, unsigned int *size);
 615
 616 extern int xt_compat_target_offset(const struct xt_target *target);
 617 extern void xt_compat_target_from_user(struct xt_entry_target *t,
 618                                        void **dstptr, unsigned int *size);
 619 extern int xt_compat_target_to_user(const struct xt_entry_target *t,
 620                                     void __user **dstptr, unsigned int *size);
 621
 622 #endif /* CONFIG_COMPAT */
 623 #endif /* __KERNEL__ */
 624
 625 #endif /* _X_TABLES_H */