include/linux/netfilter/x_tables.h

   1 #ifndef _X_TABLES_H
   2 #define _X_TABLES_H
   3
   4
   5 #include <linux/netdevice.h>
   6 #include <uapi/linux/netfilter/x_tables.h>
   7
   8 /**
   9  * struct xt_action_param - parameters for matches/targets
  10  *
  11  * @match:      the match extension
  12  * @target:     the target extension
  13  * @matchinfo:  per-match data
  14  * @targetinfo: per-target data
  15  * @in:         input netdevice
  16  * @out:        output netdevice
  17  * @fragoff:    packet is a fragment, this is the data offset
  18  * @thoff:      position of transport header relative to skb->data
  19  * @hook:       hook number given packet came from
  20  * @family:     Actual NFPROTO_* through which the function is invoked
  21  *              (helpful when match->family == NFPROTO_UNSPEC)
  22  *
  23  * Fields written to by extensions:
  24  *
  25  * @hotdrop:    drop packet if we had inspection problems
  26  * Network namespace obtainable using dev_net(in/out)
  27  */
  28 struct xt_action_param {
  29         union {
  30                 const struct xt_match *match;
  31                 const struct xt_target *target;
  32         };
  33         union {
  34                 const void *matchinfo, *targinfo;
  35         };
  36         const struct net_device *in, *out;
  37         int fragoff;
  38         unsigned int thoff;
  39         unsigned int hooknum;
  40         u_int8_t family;
  41         bool hotdrop;
  42 };
  43
  44 /**
  45  * struct xt_mtchk_param - parameters for match extensions'
  46  * checkentry functions
  47  *
  48  * @net:        network namespace through which the check was invoked
  49  * @table:      table the rule is tried to be inserted into
  50  * @entryinfo:  the family-specific rule data
  51  *              (struct ipt_ip, ip6t_ip, arpt_arp or (note) ebt_entry)
  52  * @match:      struct xt_match through which this function was invoked
  53  * @matchinfo:  per-match data
  54  * @hook_mask:  via which hooks the new rule is reachable
  55  * Other fields as above.
  56  */
  57 struct xt_mtchk_param {
  58         struct net *net;
  59         const char *table;
  60         const void *entryinfo;
  61         const struct xt_match *match;
  62         void *matchinfo;
  63         unsigned int hook_mask;
  64         u_int8_t family;
  65 };
  66
  67 /**
  68  * struct xt_mdtor_param - match destructor parameters
  69  * Fields as above.
  70  */
  71 struct xt_mtdtor_param {
  72         struct net *net;
  73         const struct xt_match *match;
  74         void *matchinfo;
  75         u_int8_t family;
  76 };
  77
  78 /**
  79  * struct xt_tgchk_param - parameters for target extensions'
  80  * checkentry functions
  81  *
  82  * @entryinfo:  the family-specific rule data
  83  *              (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
  84  *
  85  * Other fields see above.
  86  */
  87 struct xt_tgchk_param {
  88         struct net *net;
  89         const char *table;
  90         const void *entryinfo;
  91         const struct xt_target *target;
  92         void *targinfo;
  93         unsigned int hook_mask;
  94         u_int8_t family;
  95 };
  96
  97 /* Target destructor parameters */
  98 struct xt_tgdtor_param {
  99         struct net *net;
 100         const struct xt_target *target;
 101         void *targinfo;
 102         u_int8_t family;
 103 };
 104
 105 struct xt_match {
 106         struct list_head list;
 107
 108         const char name[XT_EXTENSION_MAXNAMELEN];
 109         u_int8_t revision;
 110
 111         /* Return true or false: return FALSE and set *hotdrop = 1 to
 112            force immediate packet drop. */
 113         /* Arguments changed since 2.6.9, as this must now handle
 114            non-linear skb, using skb_header_pointer and
 115            skb_ip_make_writable. */
 116         bool (*match)(const struct sk_buff *skb,
 117                       struct xt_action_param *);
 118
 119         /* Called when user tries to insert an entry of this type. */
 120         int (*checkentry)(const struct xt_mtchk_param *);
 121
 122         /* Called when entry of this type deleted. */
 123         void (*destroy)(const struct xt_mtdtor_param *);
 124 #ifdef CONFIG_COMPAT
 125         /* Called when userspace align differs from kernel space one */
 126         void (*compat_from_user)(void *dst, const void *src);
 127         int (*compat_to_user)(void __user *dst, const void *src);
 128 #endif
 129         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 130         struct module *me;
 131
 132         const char *table;
 133         unsigned int matchsize;
 134 #ifdef CONFIG_COMPAT
 135         unsigned int compatsize;
 136 #endif
 137         unsigned int hooks;
 138         unsigned short proto;
 139
 140         unsigned short family;
 141 };
 142
 143 /* Registration hooks for targets. */
 144 struct xt_target {
 145         struct list_head list;
 146
 147         const char name[XT_EXTENSION_MAXNAMELEN];
 148         u_int8_t revision;
 149
 150         /* Returns verdict. Argument order changed since 2.6.9, as this
 151            must now handle non-linear skbs, using skb_copy_bits and
 152            skb_ip_make_writable. */
 153         unsigned int (*target)(struct sk_buff *skb,
 154                                const struct xt_action_param *);
 155
 156         /* Called when user tries to insert an entry of this type:
 157            hook_mask is a bitmask of hooks from which it can be
 158            called. */
 159         /* Should return 0 on success or an error code otherwise (-Exxxx). */
 160         int (*checkentry)(const struct xt_tgchk_param *);
 161
 162         /* Called when entry of this type deleted. */
 163         void (*destroy)(const struct xt_tgdtor_param *);
 164 #ifdef CONFIG_COMPAT
 165         /* Called when userspace align differs from kernel space one */
 166         void (*compat_from_user)(void *dst, const void *src);
 167         int (*compat_to_user)(void __user *dst, const void *src);
 168 #endif
 169         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 170         struct module *me;
 171
 172         const char *table;
 173         unsigned int targetsize;
 174 #ifdef CONFIG_COMPAT
 175         unsigned int compatsize;
 176 #endif
 177         unsigned int hooks;
 178         unsigned short proto;
 179
 180         unsigned short family;
 181 };
 182
 183 /* Furniture shopping... */
 184 struct xt_table {
 185         struct list_head list;
 186
 187         /* What hooks you will enter on */
 188         unsigned int valid_hooks;
 189
 190         /* Man behind the curtain... */
 191         struct xt_table_info *private;
 192
 193         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 194         struct module *me;
 195
 196         u_int8_t af;            /* address/protocol family */
 197         int priority;           /* hook order */
 198
 199         /* A unique name... */
 200         const char name[XT_TABLE_MAXNAMELEN];
 201 };
 202
 203 #include <linux/netfilter_ipv4.h>
 204
 205 /* The table itself */
 206 struct xt_table_info {
 207         /* Size per table */
 208         unsigned int size;
 209         /* Number of entries: FIXME. --RR */
 210         unsigned int number;
 211         /* Initial number of entries. Needed for module usage count */
 212         unsigned int initial_entries;
 213
 214         /* Entry points and underflows */
 215         unsigned int hook_entry[NF_INET_NUMHOOKS];
 216         unsigned int underflow[NF_INET_NUMHOOKS];
 217
 218         /*
 219          * Number of user chains. Since tables cannot have loops, at most
 220          * @stacksize jumps (number of user chains) can possibly be made.
 221          */
 222         unsigned int stacksize;
 223         unsigned int __percpu *stackptr;
 224         void ***jumpstack;
 225         /* ipt_entry tables: one per CPU */
 226         /* Note : this field MUST be the last one, see XT_TABLE_INFO_SZ */
 227         void *entries[1];
 228 };
 229
 230 #define XT_TABLE_INFO_SZ (offsetof(struct xt_table_info, entries) \
 231                           + nr_cpu_ids * sizeof(char *))
 232 extern int xt_register_target(struct xt_target *target);
 233 extern void xt_unregister_target(struct xt_target *target);
 234 extern int xt_register_targets(struct xt_target *target, unsigned int n);
 235 extern void xt_unregister_targets(struct xt_target *target, unsigned int n);
 236
 237 extern int xt_register_match(struct xt_match *target);
 238 extern void xt_unregister_match(struct xt_match *target);
 239 extern int xt_register_matches(struct xt_match *match, unsigned int n);
 240 extern void xt_unregister_matches(struct xt_match *match, unsigned int n);
 241
 242 extern int xt_check_match(struct xt_mtchk_param *,
 243                           unsigned int size, u_int8_t proto, bool inv_proto);
 244 extern int xt_check_target(struct xt_tgchk_param *,
 245                            unsigned int size, u_int8_t proto, bool inv_proto);
 246
 247 extern struct xt_table *xt_register_table(struct net *net,
 248                                           const struct xt_table *table,
 249                                           struct xt_table_info *bootstrap,
 250                                           struct xt_table_info *newinfo);
 251 extern void *xt_unregister_table(struct xt_table *table);
 252
 253 extern struct xt_table_info *xt_replace_table(struct xt_table *table,
 254                                               unsigned int num_counters,
 255                                               struct xt_table_info *newinfo,
 256                                               int *error);
 257
 258 extern struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
 259 extern struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
 260 extern struct xt_match *xt_request_find_match(u8 af, const char *name,
 261                                               u8 revision);
 262 extern struct xt_target *xt_request_find_target(u8 af, const char *name,
 263                                                 u8 revision);
 264 extern int xt_find_revision(u8 af, const char *name, u8 revision,
 265                             int target, int *err);
 266
 267 extern struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 268                                            const char *name);
 269 extern void xt_table_unlock(struct xt_table *t);
 270
 271 extern int xt_proto_init(struct net *net, u_int8_t af);
 272 extern void xt_proto_fini(struct net *net, u_int8_t af);
 273
 274 extern struct xt_table_info *xt_alloc_table_info(unsigned int size);
 275 extern void xt_free_table_info(struct xt_table_info *info);
 276
 277 /**
 278  * xt_recseq - recursive seqcount for netfilter use
 279  *
 280  * Packet processing changes the seqcount only if no recursion happened
 281  * get_counters() can use read_seqcount_begin()/read_seqcount_retry(),
 282  * because we use the normal seqcount convention :
 283  * Low order bit set to 1 if a writer is active.
 284  */
 285 DECLARE_PER_CPU(seqcount_t, xt_recseq);
 286
 287 /**
 288  * xt_write_recseq_begin - start of a write section
 289  *
 290  * Begin packet processing : all readers must wait the end
 291  * 1) Must be called with preemption disabled
 292  * 2) softirqs must be disabled too (or we should use this_cpu_add())
 293  * Returns :
 294  *  1 if no recursion on this cpu
 295  *  0 if recursion detected
 296  */
 297 static inline unsigned int xt_write_recseq_begin(void)
 298 {
 299         unsigned int addend;
 300
 301         /*
 302          * Low order bit of sequence is set if we already
 303          * called xt_write_recseq_begin().
 304          */
 305         addend = (__this_cpu_read(xt_recseq.sequence) + 1) & 1;
 306
 307         /*
 308          * This is kind of a write_seqcount_begin(), but addend is 0 or 1
 309          * We dont check addend value to avoid a test and conditional jump,
 310          * since addend is most likely 1
 311          */
 312         __this_cpu_add(xt_recseq.sequence, addend);
 313         smp_wmb();
 314
 315         return addend;
 316 }
 317
 318 /**
 319  * xt_write_recseq_end - end of a write section
 320  * @addend: return value from previous xt_write_recseq_begin()
 321  *
 322  * End packet processing : all readers can proceed
 323  * 1) Must be called with preemption disabled
 324  * 2) softirqs must be disabled too (or we should use this_cpu_add())
 325  */
 326 static inline void xt_write_recseq_end(unsigned int addend)
 327 {
 328         /* this is kind of a write_seqcount_end(), but addend is 0 or 1 */
 329         smp_wmb();
 330         __this_cpu_add(xt_recseq.sequence, addend);
 331 }
 332
 333 /*
 334  * This helper is performance critical and must be inlined
 335  */
 336 static inline unsigned long ifname_compare_aligned(const char *_a,
 337                                                    const char *_b,
 338                                                    const char *_mask)
 339 {
 340         const unsigned long *a = (const unsigned long *)_a;
 341         const unsigned long *b = (const unsigned long *)_b;
 342         const unsigned long *mask = (const unsigned long *)_mask;
 343         unsigned long ret;
 344
 345         ret = (a[0] ^ b[0]) & mask[0];
 346         if (IFNAMSIZ > sizeof(unsigned long))
 347                 ret |= (a[1] ^ b[1]) & mask[1];
 348         if (IFNAMSIZ > 2 * sizeof(unsigned long))
 349                 ret |= (a[2] ^ b[2]) & mask[2];
 350         if (IFNAMSIZ > 3 * sizeof(unsigned long))
 351                 ret |= (a[3] ^ b[3]) & mask[3];
 352         BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
 353         return ret;
 354 }
 355
 356 extern struct nf_hook_ops *xt_hook_link(const struct xt_table *, nf_hookfn *);
 357 extern void xt_hook_unlink(const struct xt_table *, struct nf_hook_ops *);
 358
 359 #ifdef CONFIG_COMPAT
 360 #include <net/compat.h>
 361
 362 struct compat_xt_entry_match {
 363         union {
 364                 struct {
 365                         u_int16_t match_size;
 366                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 367                         u_int8_t revision;
 368                 } user;
 369                 struct {
 370                         u_int16_t match_size;
 371                         compat_uptr_t match;
 372                 } kernel;
 373                 u_int16_t match_size;
 374         } u;
 375         unsigned char data[0];
 376 };
 377
 378 struct compat_xt_entry_target {
 379         union {
 380                 struct {
 381                         u_int16_t target_size;
 382                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 383                         u_int8_t revision;
 384                 } user;
 385                 struct {
 386                         u_int16_t target_size;
 387                         compat_uptr_t target;
 388                 } kernel;
 389                 u_int16_t target_size;
 390         } u;
 391         unsigned char data[0];
 392 };
 393
 394 /* FIXME: this works only on 32 bit tasks
 395  * need to change whole approach in order to calculate align as function of
 396  * current task alignment */
 397
 398 struct compat_xt_counters {
 399         compat_u64 pcnt, bcnt;                  /* Packet and byte counters */
 400 };
 401
 402 struct compat_xt_counters_info {
 403         char name[XT_TABLE_MAXNAMELEN];
 404         compat_uint_t num_counters;
 405         struct compat_xt_counters counters[0];
 406 };
 407
 408 struct _compat_xt_align {
 409         __u8 u8;
 410         __u16 u16;
 411         __u32 u32;
 412         compat_u64 u64;
 413 };
 414
 415 #define COMPAT_XT_ALIGN(s) __ALIGN_KERNEL((s), __alignof__(struct _compat_xt_align))
 416
 417 extern void xt_compat_lock(u_int8_t af);
 418 extern void xt_compat_unlock(u_int8_t af);
 419
 420 extern int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta);
 421 extern void xt_compat_flush_offsets(u_int8_t af);
 422 extern void xt_compat_init_offsets(u_int8_t af, unsigned int number);
 423 extern int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 424
 425 extern int xt_compat_match_offset(const struct xt_match *match);
 426 extern int xt_compat_match_from_user(struct xt_entry_match *m,
 427                                      void **dstptr, unsigned int *size);
 428 extern int xt_compat_match_to_user(const struct xt_entry_match *m,
 429                                    void __user **dstptr, unsigned int *size);
 430
 431 extern int xt_compat_target_offset(const struct xt_target *target);
 432 extern void xt_compat_target_from_user(struct xt_entry_target *t,
 433                                        void **dstptr, unsigned int *size);
 434 extern int xt_compat_target_to_user(const struct xt_entry_target *t,
 435                                     void __user **dstptr, unsigned int *size);
 436
 437 #endif /* CONFIG_COMPAT */
 438 #endif /* _X_TABLES_H */