include/linux/netfilter/x_tables.h

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