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  * Network namespace obtainable using dev_net(in/out)
 201  */
 202 struct xt_match_param {
 203         const struct net_device *in, *out;
 204         const struct xt_match *match;
 205         const void *matchinfo;
 206         int fragoff;
 207         unsigned int thoff;
 208         unsigned int hooknum;
 209         u_int8_t family;
 210         bool *hotdrop;
 211 };
 212
 213 /**
 214  * struct xt_mtchk_param - parameters for match extensions'
 215  * checkentry functions
 216  *
 217  * @net:        network namespace through which the check was invoked
 218  * @table:      table the rule is tried to be inserted into
 219  * @entryinfo:  the family-specific rule data
 220  *              (struct ipt_ip, ip6t_ip, arpt_arp or (note) ebt_entry)
 221  * @match:      struct xt_match through which this function was invoked
 222  * @matchinfo:  per-match data
 223  * @hook_mask:  via which hooks the new rule is reachable
 224  * Other fields as above.
 225  */
 226 struct xt_mtchk_param {
 227         struct net *net;
 228         const char *table;
 229         const void *entryinfo;
 230         const struct xt_match *match;
 231         void *matchinfo;
 232         unsigned int hook_mask;
 233         u_int8_t family;
 234 };
 235
 236 /**
 237  * struct xt_mdtor_param - match destructor parameters
 238  * Fields as above.
 239  */
 240 struct xt_mtdtor_param {
 241         struct net *net;
 242         const struct xt_match *match;
 243         void *matchinfo;
 244         u_int8_t family;
 245 };
 246
 247 /**
 248  * struct xt_target_param - parameters for target extensions' target functions
 249  *
 250  * @hooknum:    hook through which this target was invoked
 251  * @target:     struct xt_target through which this function was invoked
 252  * @targinfo:   per-target data
 253  *
 254  * Other fields see above.
 255  */
 256 struct xt_target_param {
 257         const struct net_device *in, *out;
 258         const struct xt_target *target;
 259         const void *targinfo;
 260         unsigned int hooknum;
 261         u_int8_t family;
 262 };
 263
 264 /**
 265  * struct xt_tgchk_param - parameters for target extensions'
 266  * checkentry functions
 267  *
 268  * @entryinfo:  the family-specific rule data
 269  *              (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
 270  *
 271  * Other fields see above.
 272  */
 273 struct xt_tgchk_param {
 274         struct net *net;
 275         const char *table;
 276         const void *entryinfo;
 277         const struct xt_target *target;
 278         void *targinfo;
 279         unsigned int hook_mask;
 280         u_int8_t family;
 281 };
 282
 283 /* Target destructor parameters */
 284 struct xt_tgdtor_param {
 285         struct net *net;
 286         const struct xt_target *target;
 287         void *targinfo;
 288         u_int8_t family;
 289 };
 290
 291 struct xt_match {
 292         struct list_head list;
 293
 294         const char name[XT_FUNCTION_MAXNAMELEN-1];
 295         u_int8_t revision;
 296
 297         /* Return true or false: return FALSE and set *hotdrop = 1 to
 298            force immediate packet drop. */
 299         /* Arguments changed since 2.6.9, as this must now handle
 300            non-linear skb, using skb_header_pointer and
 301            skb_ip_make_writable. */
 302         bool (*match)(const struct sk_buff *skb,
 303                       const struct xt_match_param *);
 304
 305         /* Called when user tries to insert an entry of this type. */
 306         int (*checkentry)(const struct xt_mtchk_param *);
 307
 308         /* Called when entry of this type deleted. */
 309         void (*destroy)(const struct xt_mtdtor_param *);
 310 #ifdef CONFIG_COMPAT
 311         /* Called when userspace align differs from kernel space one */
 312         void (*compat_from_user)(void *dst, const void *src);
 313         int (*compat_to_user)(void __user *dst, const void *src);
 314 #endif
 315         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 316         struct module *me;
 317
 318         const char *table;
 319         unsigned int matchsize;
 320 #ifdef CONFIG_COMPAT
 321         unsigned int compatsize;
 322 #endif
 323         unsigned int hooks;
 324         unsigned short proto;
 325
 326         unsigned short family;
 327 };
 328
 329 /* Registration hooks for targets. */
 330 struct xt_target {
 331         struct list_head list;
 332
 333         const char name[XT_FUNCTION_MAXNAMELEN-1];
 334         u_int8_t revision;
 335
 336         /* Returns verdict. Argument order changed since 2.6.9, as this
 337            must now handle non-linear skbs, using skb_copy_bits and
 338            skb_ip_make_writable. */
 339         unsigned int (*target)(struct sk_buff *skb,
 340                                const struct xt_target_param *);
 341
 342         /* Called when user tries to insert an entry of this type:
 343            hook_mask is a bitmask of hooks from which it can be
 344            called. */
 345         /* Should return true or false, or an error code (-Exxxx). */
 346         int (*checkentry)(const struct xt_tgchk_param *);
 347
 348         /* Called when entry of this type deleted. */
 349         void (*destroy)(const struct xt_tgdtor_param *);
 350 #ifdef CONFIG_COMPAT
 351         /* Called when userspace align differs from kernel space one */
 352         void (*compat_from_user)(void *dst, const void *src);
 353         int (*compat_to_user)(void __user *dst, const void *src);
 354 #endif
 355         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 356         struct module *me;
 357
 358         const char *table;
 359         unsigned int targetsize;
 360 #ifdef CONFIG_COMPAT
 361         unsigned int compatsize;
 362 #endif
 363         unsigned int hooks;
 364         unsigned short proto;
 365
 366         unsigned short family;
 367 };
 368
 369 /* Furniture shopping... */
 370 struct xt_table {
 371         struct list_head list;
 372
 373         /* What hooks you will enter on */
 374         unsigned int valid_hooks;
 375
 376         /* Man behind the curtain... */
 377         struct xt_table_info *private;
 378
 379         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 380         struct module *me;
 381
 382         u_int8_t af;            /* address/protocol family */
 383         int priority;           /* hook order */
 384
 385         /* A unique name... */
 386         const char name[XT_TABLE_MAXNAMELEN];
 387 };
 388
 389 #include <linux/netfilter_ipv4.h>
 390
 391 /* The table itself */
 392 struct xt_table_info {
 393         /* Size per table */
 394         unsigned int size;
 395         /* Number of entries: FIXME. --RR */
 396         unsigned int number;
 397         /* Initial number of entries. Needed for module usage count */
 398         unsigned int initial_entries;
 399
 400         /* Entry points and underflows */
 401         unsigned int hook_entry[NF_INET_NUMHOOKS];
 402         unsigned int underflow[NF_INET_NUMHOOKS];
 403
 404         /* ipt_entry tables: one per CPU */
 405         /* Note : this field MUST be the last one, see XT_TABLE_INFO_SZ */
 406         void *entries[1];
 407 };
 408
 409 #define XT_TABLE_INFO_SZ (offsetof(struct xt_table_info, entries) \
 410                           + nr_cpu_ids * sizeof(char *))
 411 extern int xt_register_target(struct xt_target *target);
 412 extern void xt_unregister_target(struct xt_target *target);
 413 extern int xt_register_targets(struct xt_target *target, unsigned int n);
 414 extern void xt_unregister_targets(struct xt_target *target, unsigned int n);
 415
 416 extern int xt_register_match(struct xt_match *target);
 417 extern void xt_unregister_match(struct xt_match *target);
 418 extern int xt_register_matches(struct xt_match *match, unsigned int n);
 419 extern void xt_unregister_matches(struct xt_match *match, unsigned int n);
 420
 421 extern int xt_check_match(struct xt_mtchk_param *,
 422                           unsigned int size, u_int8_t proto, bool inv_proto);
 423 extern int xt_check_target(struct xt_tgchk_param *,
 424                            unsigned int size, u_int8_t proto, bool inv_proto);
 425
 426 extern struct xt_table *xt_register_table(struct net *net,
 427                                           const struct xt_table *table,
 428                                           struct xt_table_info *bootstrap,
 429                                           struct xt_table_info *newinfo);
 430 extern void *xt_unregister_table(struct xt_table *table);
 431
 432 extern struct xt_table_info *xt_replace_table(struct xt_table *table,
 433                                               unsigned int num_counters,
 434                                               struct xt_table_info *newinfo,
 435                                               int *error);
 436
 437 extern struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
 438 extern struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
 439 extern struct xt_match *xt_request_find_match(u8 af, const char *name,
 440                                               u8 revision);
 441 extern struct xt_target *xt_request_find_target(u8 af, const char *name,
 442                                                 u8 revision);
 443 extern int xt_find_revision(u8 af, const char *name, u8 revision,
 444                             int target, int *err);
 445
 446 extern struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 447                                            const char *name);
 448 extern void xt_table_unlock(struct xt_table *t);
 449
 450 extern int xt_proto_init(struct net *net, u_int8_t af);
 451 extern void xt_proto_fini(struct net *net, u_int8_t af);
 452
 453 extern struct xt_table_info *xt_alloc_table_info(unsigned int size);
 454 extern void xt_free_table_info(struct xt_table_info *info);
 455
 456 /*
 457  * Per-CPU spinlock associated with per-cpu table entries, and
 458  * with a counter for the "reading" side that allows a recursive
 459  * reader to avoid taking the lock and deadlocking.
 460  *
 461  * "reading" is used by ip/arp/ip6 tables rule processing which runs per-cpu.
 462  * It needs to ensure that the rules are not being changed while the packet
 463  * is being processed. In some cases, the read lock will be acquired
 464  * twice on the same CPU; this is okay because of the count.
 465  *
 466  * "writing" is used when reading counters.
 467  *  During replace any readers that are using the old tables have to complete
 468  *  before freeing the old table. This is handled by the write locking
 469  *  necessary for reading the counters.
 470  */
 471 struct xt_info_lock {
 472         spinlock_t lock;
 473         unsigned char readers;
 474 };
 475 DECLARE_PER_CPU(struct xt_info_lock, xt_info_locks);
 476
 477 /*
 478  * Note: we need to ensure that preemption is disabled before acquiring
 479  * the per-cpu-variable, so we do it as a two step process rather than
 480  * using "spin_lock_bh()".
 481  *
 482  * We _also_ need to disable bottom half processing before updating our
 483  * nesting count, to make sure that the only kind of re-entrancy is this
 484  * code being called by itself: since the count+lock is not an atomic
 485  * operation, we can allow no races.
 486  *
 487  * _Only_ that special combination of being per-cpu and never getting
 488  * re-entered asynchronously means that the count is safe.
 489  */
 490 static inline void xt_info_rdlock_bh(void)
 491 {
 492         struct xt_info_lock *lock;
 493
 494         local_bh_disable();
 495         lock = &__get_cpu_var(xt_info_locks);
 496         if (likely(!lock->readers++))
 497                 spin_lock(&lock->lock);
 498 }
 499
 500 static inline void xt_info_rdunlock_bh(void)
 501 {
 502         struct xt_info_lock *lock = &__get_cpu_var(xt_info_locks);
 503
 504         if (likely(!--lock->readers))
 505                 spin_unlock(&lock->lock);
 506         local_bh_enable();
 507 }
 508
 509 /*
 510  * The "writer" side needs to get exclusive access to the lock,
 511  * regardless of readers.  This must be called with bottom half
 512  * processing (and thus also preemption) disabled.
 513  */
 514 static inline void xt_info_wrlock(unsigned int cpu)
 515 {
 516         spin_lock(&per_cpu(xt_info_locks, cpu).lock);
 517 }
 518
 519 static inline void xt_info_wrunlock(unsigned int cpu)
 520 {
 521         spin_unlock(&per_cpu(xt_info_locks, cpu).lock);
 522 }
 523
 524 /*
 525  * This helper is performance critical and must be inlined
 526  */
 527 static inline unsigned long ifname_compare_aligned(const char *_a,
 528                                                    const char *_b,
 529                                                    const char *_mask)
 530 {
 531         const unsigned long *a = (const unsigned long *)_a;
 532         const unsigned long *b = (const unsigned long *)_b;
 533         const unsigned long *mask = (const unsigned long *)_mask;
 534         unsigned long ret;
 535
 536         ret = (a[0] ^ b[0]) & mask[0];
 537         if (IFNAMSIZ > sizeof(unsigned long))
 538                 ret |= (a[1] ^ b[1]) & mask[1];
 539         if (IFNAMSIZ > 2 * sizeof(unsigned long))
 540                 ret |= (a[2] ^ b[2]) & mask[2];
 541         if (IFNAMSIZ > 3 * sizeof(unsigned long))
 542                 ret |= (a[3] ^ b[3]) & mask[3];
 543         BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
 544         return ret;
 545 }
 546
 547 extern struct nf_hook_ops *xt_hook_link(const struct xt_table *, nf_hookfn *);
 548 extern void xt_hook_unlink(const struct xt_table *, struct nf_hook_ops *);
 549
 550 #ifdef CONFIG_COMPAT
 551 #include <net/compat.h>
 552
 553 struct compat_xt_entry_match {
 554         union {
 555                 struct {
 556                         u_int16_t match_size;
 557                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 558                         u_int8_t revision;
 559                 } user;
 560                 struct {
 561                         u_int16_t match_size;
 562                         compat_uptr_t match;
 563                 } kernel;
 564                 u_int16_t match_size;
 565         } u;
 566         unsigned char data[0];
 567 };
 568
 569 struct compat_xt_entry_target {
 570         union {
 571                 struct {
 572                         u_int16_t target_size;
 573                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 574                         u_int8_t revision;
 575                 } user;
 576                 struct {
 577                         u_int16_t target_size;
 578                         compat_uptr_t target;
 579                 } kernel;
 580                 u_int16_t target_size;
 581         } u;
 582         unsigned char data[0];
 583 };
 584
 585 /* FIXME: this works only on 32 bit tasks
 586  * need to change whole approach in order to calculate align as function of
 587  * current task alignment */
 588
 589 struct compat_xt_counters {
 590         compat_u64 pcnt, bcnt;                  /* Packet and byte counters */
 591 };
 592
 593 struct compat_xt_counters_info {
 594         char name[XT_TABLE_MAXNAMELEN];
 595         compat_uint_t num_counters;
 596         struct compat_xt_counters counters[0];
 597 };
 598
 599 struct _compat_xt_align {
 600         __u8 u8;
 601         __u16 u16;
 602         __u32 u32;
 603         compat_u64 u64;
 604 };
 605
 606 #define COMPAT_XT_ALIGN(s) ALIGN((s), __alignof__(struct _compat_xt_align))
 607
 608 extern void xt_compat_lock(u_int8_t af);
 609 extern void xt_compat_unlock(u_int8_t af);
 610
 611 extern int xt_compat_add_offset(u_int8_t af, unsigned int offset, short delta);
 612 extern void xt_compat_flush_offsets(u_int8_t af);
 613 extern int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 614
 615 extern int xt_compat_match_offset(const struct xt_match *match);
 616 extern int xt_compat_match_from_user(struct xt_entry_match *m,
 617                                      void **dstptr, unsigned int *size);
 618 extern int xt_compat_match_to_user(const struct xt_entry_match *m,
 619                                    void __user **dstptr, unsigned int *size);
 620
 621 extern int xt_compat_target_offset(const struct xt_target *target);
 622 extern void xt_compat_target_from_user(struct xt_entry_target *t,
 623                                        void **dstptr, unsigned int *size);
 624 extern int xt_compat_target_to_user(const struct xt_entry_target *t,
 625                                     void __user **dstptr, unsigned int *size);
 626
 627 #endif /* CONFIG_COMPAT */
 628 #endif /* __KERNEL__ */
 629
 630 #endif /* _X_TABLES_H */