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