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) (((s) + (__alignof__(struct _xt_align)-1))  \
  97                         & ~(__alignof__(struct _xt_align)-1))
  98
  99 /* Standard return verdict, or do jump. */
 100 #define XT_STANDARD_TARGET ""
 101 /* Error verdict. */
 102 #define XT_ERROR_TARGET "ERROR"
 103
 104 #define SET_COUNTER(c,b,p) do { (c).bcnt = (b); (c).pcnt = (p); } while(0)
 105 #define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)
 106
 107 struct xt_counters {
 108         __u64 pcnt, bcnt;                       /* Packet and byte counters */
 109 };
 110
 111 /* The argument to IPT_SO_ADD_COUNTERS. */
 112 struct xt_counters_info {
 113         /* Which table. */
 114         char name[XT_TABLE_MAXNAMELEN];
 115
 116         unsigned int num_counters;
 117
 118         /* The counters (actually `number' of these). */
 119         struct xt_counters counters[0];
 120 };
 121
 122 #define XT_INV_PROTO            0x40    /* Invert the sense of PROTO. */
 123
 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 #ifdef __KERNEL__
 168
 169 #include <linux/netdevice.h>
 170
 171 /**
 172  * struct xt_match_param - parameters for match extensions' match functions
 173  *
 174  * @in:         input netdevice
 175  * @out:        output netdevice
 176  * @match:      struct xt_match through which this function was invoked
 177  * @matchinfo:  per-match data
 178  * @fragoff:    packet is a fragment, this is the data offset
 179  * @thoff:      position of transport header relative to skb->data
 180  * @hook:       hook number given packet came from
 181  * @family:     Actual NFPROTO_* through which the function is invoked
 182  *              (helpful when match->family == NFPROTO_UNSPEC)
 183  * @hotdrop:    drop packet if we had inspection problems
 184  */
 185 struct xt_match_param {
 186         const struct net_device *in, *out;
 187         const struct xt_match *match;
 188         const void *matchinfo;
 189         int fragoff;
 190         unsigned int thoff;
 191         unsigned int hooknum;
 192         u_int8_t family;
 193         bool *hotdrop;
 194 };
 195
 196 /**
 197  * struct xt_mtchk_param - parameters for match extensions'
 198  * checkentry functions
 199  *
 200  * @table:      table the rule is tried to be inserted into
 201  * @entryinfo:  the family-specific rule data
 202  *              (struct ipt_ip, ip6t_ip, ebt_entry)
 203  * @match:      struct xt_match through which this function was invoked
 204  * @matchinfo:  per-match data
 205  * @hook_mask:  via which hooks the new rule is reachable
 206  */
 207 struct xt_mtchk_param {
 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         const struct xt_match *match;
 219         void *matchinfo;
 220         u_int8_t family;
 221 };
 222
 223 /**
 224  * struct xt_target_param - parameters for target extensions' target functions
 225  *
 226  * @hooknum:    hook through which this target was invoked
 227  * @target:     struct xt_target through which this function was invoked
 228  * @targinfo:   per-target data
 229  *
 230  * Other fields see above.
 231  */
 232 struct xt_target_param {
 233         const struct net_device *in, *out;
 234         const struct xt_target *target;
 235         const void *targinfo;
 236         unsigned int hooknum;
 237         u_int8_t family;
 238 };
 239
 240 /**
 241  * struct xt_tgchk_param - parameters for target extensions'
 242  * checkentry functions
 243  *
 244  * @entryinfo:  the family-specific rule data
 245  *              (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
 246  *
 247  * Other fields see above.
 248  */
 249 struct xt_tgchk_param {
 250         const char *table;
 251         const void *entryinfo;
 252         const struct xt_target *target;
 253         void *targinfo;
 254         unsigned int hook_mask;
 255         u_int8_t family;
 256 };
 257
 258 /* Target destructor parameters */
 259 struct xt_tgdtor_param {
 260         const struct xt_target *target;
 261         void *targinfo;
 262         u_int8_t family;
 263 };
 264
 265 struct xt_match {
 266         struct list_head list;
 267
 268         const char name[XT_FUNCTION_MAXNAMELEN-1];
 269         u_int8_t revision;
 270
 271         /* Return true or false: return FALSE and set *hotdrop = 1 to
 272            force immediate packet drop. */
 273         /* Arguments changed since 2.6.9, as this must now handle
 274            non-linear skb, using skb_header_pointer and
 275            skb_ip_make_writable. */
 276         bool (*match)(const struct sk_buff *skb,
 277                       const struct xt_match_param *);
 278
 279         /* Called when user tries to insert an entry of this type. */
 280         bool (*checkentry)(const struct xt_mtchk_param *);
 281
 282         /* Called when entry of this type deleted. */
 283         void (*destroy)(const struct xt_mtdtor_param *);
 284
 285         /* Called when userspace align differs from kernel space one */
 286         void (*compat_from_user)(void *dst, void *src);
 287         int (*compat_to_user)(void __user *dst, void *src);
 288
 289         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 290         struct module *me;
 291
 292         /* Free to use by each match */
 293         unsigned long data;
 294
 295         const char *table;
 296         unsigned int matchsize;
 297         unsigned int compatsize;
 298         unsigned int hooks;
 299         unsigned short proto;
 300
 301         unsigned short family;
 302 };
 303
 304 /* Registration hooks for targets. */
 305 struct xt_target {
 306         struct list_head list;
 307
 308         const char name[XT_FUNCTION_MAXNAMELEN-1];
 309
 310         /* Returns verdict. Argument order changed since 2.6.9, as this
 311            must now handle non-linear skbs, using skb_copy_bits and
 312            skb_ip_make_writable. */
 313         unsigned int (*target)(struct sk_buff *skb,
 314                                const struct xt_target_param *);
 315
 316         /* Called when user tries to insert an entry of this type:
 317            hook_mask is a bitmask of hooks from which it can be
 318            called. */
 319         /* Should return true or false. */
 320         bool (*checkentry)(const struct xt_tgchk_param *);
 321
 322         /* Called when entry of this type deleted. */
 323         void (*destroy)(const struct xt_tgdtor_param *);
 324
 325         /* Called when userspace align differs from kernel space one */
 326         void (*compat_from_user)(void *dst, void *src);
 327         int (*compat_to_user)(void __user *dst, void *src);
 328
 329         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 330         struct module *me;
 331
 332         const char *table;
 333         unsigned int targetsize;
 334         unsigned int compatsize;
 335         unsigned int hooks;
 336         unsigned short proto;
 337
 338         unsigned short family;
 339         u_int8_t revision;
 340 };
 341
 342 /* Furniture shopping... */
 343 struct xt_table {
 344         struct list_head list;
 345
 346         /* What hooks you will enter on */
 347         unsigned int valid_hooks;
 348
 349         /* Man behind the curtain... */
 350         struct xt_table_info *private;
 351
 352         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 353         struct module *me;
 354
 355         u_int8_t af;            /* address/protocol family */
 356
 357         /* A unique name... */
 358         const char name[XT_TABLE_MAXNAMELEN];
 359 };
 360
 361 #include <linux/netfilter_ipv4.h>
 362
 363 /* The table itself */
 364 struct xt_table_info {
 365         /* Size per table */
 366         unsigned int size;
 367         /* Number of entries: FIXME. --RR */
 368         unsigned int number;
 369         /* Initial number of entries. Needed for module usage count */
 370         unsigned int initial_entries;
 371
 372         /* Entry points and underflows */
 373         unsigned int hook_entry[NF_INET_NUMHOOKS];
 374         unsigned int underflow[NF_INET_NUMHOOKS];
 375
 376         /* ipt_entry tables: one per CPU */
 377         /* Note : this field MUST be the last one, see XT_TABLE_INFO_SZ */
 378         void *entries[1];
 379 };
 380
 381 #define XT_TABLE_INFO_SZ (offsetof(struct xt_table_info, entries) \
 382                           + nr_cpu_ids * sizeof(char *))
 383 extern int xt_register_target(struct xt_target *target);
 384 extern void xt_unregister_target(struct xt_target *target);
 385 extern int xt_register_targets(struct xt_target *target, unsigned int n);
 386 extern void xt_unregister_targets(struct xt_target *target, unsigned int n);
 387
 388 extern int xt_register_match(struct xt_match *target);
 389 extern void xt_unregister_match(struct xt_match *target);
 390 extern int xt_register_matches(struct xt_match *match, unsigned int n);
 391 extern void xt_unregister_matches(struct xt_match *match, unsigned int n);
 392
 393 extern int xt_check_match(struct xt_mtchk_param *,
 394                           unsigned int size, u_int8_t proto, bool inv_proto);
 395 extern int xt_check_target(struct xt_tgchk_param *,
 396                            unsigned int size, u_int8_t proto, bool inv_proto);
 397
 398 extern struct xt_table *xt_register_table(struct net *net,
 399                                           const struct xt_table *table,
 400                                           struct xt_table_info *bootstrap,
 401                                           struct xt_table_info *newinfo);
 402 extern void *xt_unregister_table(struct xt_table *table);
 403
 404 extern struct xt_table_info *xt_replace_table(struct xt_table *table,
 405                                               unsigned int num_counters,
 406                                               struct xt_table_info *newinfo,
 407                                               int *error);
 408
 409 extern struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
 410 extern struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
 411 extern struct xt_target *xt_request_find_target(u8 af, const char *name,
 412                                                 u8 revision);
 413 extern int xt_find_revision(u8 af, const char *name, u8 revision,
 414                             int target, int *err);
 415
 416 extern struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 417                                            const char *name);
 418 extern void xt_table_unlock(struct xt_table *t);
 419
 420 extern int xt_proto_init(struct net *net, u_int8_t af);
 421 extern void xt_proto_fini(struct net *net, u_int8_t af);
 422
 423 extern struct xt_table_info *xt_alloc_table_info(unsigned int size);
 424 extern void xt_free_table_info(struct xt_table_info *info);
 425
 426 /*
 427  * Per-CPU spinlock associated with per-cpu table entries, and
 428  * with a counter for the "reading" side that allows a recursive
 429  * reader to avoid taking the lock and deadlocking.
 430  *
 431  * "reading" is used by ip/arp/ip6 tables rule processing which runs per-cpu.
 432  * It needs to ensure that the rules are not being changed while the packet
 433  * is being processed. In some cases, the read lock will be acquired
 434  * twice on the same CPU; this is okay because of the count.
 435  *
 436  * "writing" is used when reading counters.
 437  *  During replace any readers that are using the old tables have to complete
 438  *  before freeing the old table. This is handled by the write locking
 439  *  necessary for reading the counters.
 440  */
 441 struct xt_info_lock {
 442         spinlock_t lock;
 443         unsigned char readers;
 444 };
 445 DECLARE_PER_CPU(struct xt_info_lock, xt_info_locks);
 446
 447 /*
 448  * Note: we need to ensure that preemption is disabled before acquiring
 449  * the per-cpu-variable, so we do it as a two step process rather than
 450  * using "spin_lock_bh()".
 451  *
 452  * We _also_ need to disable bottom half processing before updating our
 453  * nesting count, to make sure that the only kind of re-entrancy is this
 454  * code being called by itself: since the count+lock is not an atomic
 455  * operation, we can allow no races.
 456  *
 457  * _Only_ that special combination of being per-cpu and never getting
 458  * re-entered asynchronously means that the count is safe.
 459  */
 460 static inline void xt_info_rdlock_bh(void)
 461 {
 462         struct xt_info_lock *lock;
 463
 464         local_bh_disable();
 465         lock = &__get_cpu_var(xt_info_locks);
 466         if (likely(!lock->readers++))
 467                 spin_lock(&lock->lock);
 468 }
 469
 470 static inline void xt_info_rdunlock_bh(void)
 471 {
 472         struct xt_info_lock *lock = &__get_cpu_var(xt_info_locks);
 473
 474         if (likely(!--lock->readers))
 475                 spin_unlock(&lock->lock);
 476         local_bh_enable();
 477 }
 478
 479 /*
 480  * The "writer" side needs to get exclusive access to the lock,
 481  * regardless of readers.  This must be called with bottom half
 482  * processing (and thus also preemption) disabled.
 483  */
 484 static inline void xt_info_wrlock(unsigned int cpu)
 485 {
 486         spin_lock(&per_cpu(xt_info_locks, cpu).lock);
 487 }
 488
 489 static inline void xt_info_wrunlock(unsigned int cpu)
 490 {
 491         spin_unlock(&per_cpu(xt_info_locks, cpu).lock);
 492 }
 493
 494 /*
 495  * This helper is performance critical and must be inlined
 496  */
 497 static inline unsigned long ifname_compare_aligned(const char *_a,
 498                                                    const char *_b,
 499                                                    const char *_mask)
 500 {
 501         const unsigned long *a = (const unsigned long *)_a;
 502         const unsigned long *b = (const unsigned long *)_b;
 503         const unsigned long *mask = (const unsigned long *)_mask;
 504         unsigned long ret;
 505
 506         ret = (a[0] ^ b[0]) & mask[0];
 507         if (IFNAMSIZ > sizeof(unsigned long))
 508                 ret |= (a[1] ^ b[1]) & mask[1];
 509         if (IFNAMSIZ > 2 * sizeof(unsigned long))
 510                 ret |= (a[2] ^ b[2]) & mask[2];
 511         if (IFNAMSIZ > 3 * sizeof(unsigned long))
 512                 ret |= (a[3] ^ b[3]) & mask[3];
 513         BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
 514         return ret;
 515 }
 516
 517 #ifdef CONFIG_COMPAT
 518 #include <net/compat.h>
 519
 520 struct compat_xt_entry_match {
 521         union {
 522                 struct {
 523                         u_int16_t match_size;
 524                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 525                         u_int8_t revision;
 526                 } user;
 527                 struct {
 528                         u_int16_t match_size;
 529                         compat_uptr_t match;
 530                 } kernel;
 531                 u_int16_t match_size;
 532         } u;
 533         unsigned char data[0];
 534 };
 535
 536 struct compat_xt_entry_target {
 537         union {
 538                 struct {
 539                         u_int16_t target_size;
 540                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 541                         u_int8_t revision;
 542                 } user;
 543                 struct {
 544                         u_int16_t target_size;
 545                         compat_uptr_t target;
 546                 } kernel;
 547                 u_int16_t target_size;
 548         } u;
 549         unsigned char data[0];
 550 };
 551
 552 /* FIXME: this works only on 32 bit tasks
 553  * need to change whole approach in order to calculate align as function of
 554  * current task alignment */
 555
 556 struct compat_xt_counters {
 557 #if defined(CONFIG_X86_64) || defined(CONFIG_IA64)
 558         u_int32_t cnt[4];
 559 #else
 560         u_int64_t cnt[2];
 561 #endif
 562 };
 563
 564 struct compat_xt_counters_info {
 565         char name[XT_TABLE_MAXNAMELEN];
 566         compat_uint_t num_counters;
 567         struct compat_xt_counters counters[0];
 568 };
 569
 570 #define COMPAT_XT_ALIGN(s) (((s) + (__alignof__(struct compat_xt_counters)-1)) \
 571                 & ~(__alignof__(struct compat_xt_counters)-1))
 572
 573 extern void xt_compat_lock(u_int8_t af);
 574 extern void xt_compat_unlock(u_int8_t af);
 575
 576 extern int xt_compat_add_offset(u_int8_t af, unsigned int offset, short delta);
 577 extern void xt_compat_flush_offsets(u_int8_t af);
 578 extern short xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 579
 580 extern int xt_compat_match_offset(const struct xt_match *match);
 581 extern int xt_compat_match_from_user(struct xt_entry_match *m,
 582                                      void **dstptr, unsigned int *size);
 583 extern int xt_compat_match_to_user(struct xt_entry_match *m,
 584                                    void __user **dstptr, unsigned int *size);
 585
 586 extern int xt_compat_target_offset(const struct xt_target *target);
 587 extern void xt_compat_target_from_user(struct xt_entry_target *t,
 588                                        void **dstptr, unsigned int *size);
 589 extern int xt_compat_target_to_user(struct xt_entry_target *t,
 590                                     void __user **dstptr, unsigned int *size);
 591
 592 #endif /* CONFIG_COMPAT */
 593 #endif /* __KERNEL__ */
 594
 595 #endif /* _X_TABLES_H */