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 <linux/static_key.h>
   7 #include <uapi/linux/netfilter/x_tables.h>
   8
   9 /**
  10  * struct xt_action_param - parameters for matches/targets
  11  *
  12  * @match:      the match extension
  13  * @target:     the target extension
  14  * @matchinfo:  per-match data
  15  * @targetinfo: per-target data
  16  * @net         network namespace through which the action was invoked
  17  * @in:         input netdevice
  18  * @out:        output netdevice
  19  * @fragoff:    packet is a fragment, this is the data offset
  20  * @thoff:      position of transport header relative to skb->data
  21  * @hook:       hook number given packet came from
  22  * @family:     Actual NFPROTO_* through which the function is invoked
  23  *              (helpful when match->family == NFPROTO_UNSPEC)
  24  *
  25  * Fields written to by extensions:
  26  *
  27  * @hotdrop:    drop packet if we had inspection problems
  28  */
  29 struct xt_action_param {
  30         union {
  31                 const struct xt_match *match;
  32                 const struct xt_target *target;
  33         };
  34         union {
  35                 const void *matchinfo, *targinfo;
  36         };
  37         struct net *net;
  38         const struct net_device *in, *out;
  39         int fragoff;
  40         unsigned int thoff;
  41         unsigned int hooknum;
  42         u_int8_t family;
  43         bool hotdrop;
  44 };
  45
  46 /**
  47  * struct xt_mtchk_param - parameters for match extensions'
  48  * checkentry functions
  49  *
  50  * @net:        network namespace through which the check was invoked
  51  * @table:      table the rule is tried to be inserted into
  52  * @entryinfo:  the family-specific rule data
  53  *              (struct ipt_ip, ip6t_ip, arpt_arp or (note) ebt_entry)
  54  * @match:      struct xt_match through which this function was invoked
  55  * @matchinfo:  per-match data
  56  * @hook_mask:  via which hooks the new rule is reachable
  57  * Other fields as above.
  58  */
  59 struct xt_mtchk_param {
  60         struct net *net;
  61         const char *table;
  62         const void *entryinfo;
  63         const struct xt_match *match;
  64         void *matchinfo;
  65         unsigned int hook_mask;
  66         u_int8_t family;
  67         bool nft_compat;
  68 };
  69
  70 /**
  71  * struct xt_mdtor_param - match destructor parameters
  72  * Fields as above.
  73  */
  74 struct xt_mtdtor_param {
  75         struct net *net;
  76         const struct xt_match *match;
  77         void *matchinfo;
  78         u_int8_t family;
  79 };
  80
  81 /**
  82  * struct xt_tgchk_param - parameters for target extensions'
  83  * checkentry functions
  84  *
  85  * @entryinfo:  the family-specific rule data
  86  *              (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
  87  *
  88  * Other fields see above.
  89  */
  90 struct xt_tgchk_param {
  91         struct net *net;
  92         const char *table;
  93         const void *entryinfo;
  94         const struct xt_target *target;
  95         void *targinfo;
  96         unsigned int hook_mask;
  97         u_int8_t family;
  98         bool nft_compat;
  99 };
 100
 101 /* Target destructor parameters */
 102 struct xt_tgdtor_param {
 103         struct net *net;
 104         const struct xt_target *target;
 105         void *targinfo;
 106         u_int8_t family;
 107 };
 108
 109 struct xt_match {
 110         struct list_head list;
 111
 112         const char name[XT_EXTENSION_MAXNAMELEN];
 113         u_int8_t revision;
 114
 115         /* Return true or false: return FALSE and set *hotdrop = 1 to
 116            force immediate packet drop. */
 117         /* Arguments changed since 2.6.9, as this must now handle
 118            non-linear skb, using skb_header_pointer and
 119            skb_ip_make_writable. */
 120         bool (*match)(const struct sk_buff *skb,
 121                       struct xt_action_param *);
 122
 123         /* Called when user tries to insert an entry of this type. */
 124         int (*checkentry)(const struct xt_mtchk_param *);
 125
 126         /* Called when entry of this type deleted. */
 127         void (*destroy)(const struct xt_mtdtor_param *);
 128 #ifdef CONFIG_COMPAT
 129         /* Called when userspace align differs from kernel space one */
 130         void (*compat_from_user)(void *dst, const void *src);
 131         int (*compat_to_user)(void __user *dst, const void *src);
 132 #endif
 133         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 134         struct module *me;
 135
 136         const char *table;
 137         unsigned int matchsize;
 138 #ifdef CONFIG_COMPAT
 139         unsigned int compatsize;
 140 #endif
 141         unsigned int hooks;
 142         unsigned short proto;
 143
 144         unsigned short family;
 145 };
 146
 147 /* Registration hooks for targets. */
 148 struct xt_target {
 149         struct list_head list;
 150
 151         const char name[XT_EXTENSION_MAXNAMELEN];
 152         u_int8_t revision;
 153
 154         /* Returns verdict. Argument order changed since 2.6.9, as this
 155            must now handle non-linear skbs, using skb_copy_bits and
 156            skb_ip_make_writable. */
 157         unsigned int (*target)(struct sk_buff *skb,
 158                                const struct xt_action_param *);
 159
 160         /* Called when user tries to insert an entry of this type:
 161            hook_mask is a bitmask of hooks from which it can be
 162            called. */
 163         /* Should return 0 on success or an error code otherwise (-Exxxx). */
 164         int (*checkentry)(const struct xt_tgchk_param *);
 165
 166         /* Called when entry of this type deleted. */
 167         void (*destroy)(const struct xt_tgdtor_param *);
 168 #ifdef CONFIG_COMPAT
 169         /* Called when userspace align differs from kernel space one */
 170         void (*compat_from_user)(void *dst, const void *src);
 171         int (*compat_to_user)(void __user *dst, const void *src);
 172 #endif
 173         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 174         struct module *me;
 175
 176         const char *table;
 177         unsigned int targetsize;
 178 #ifdef CONFIG_COMPAT
 179         unsigned int compatsize;
 180 #endif
 181         unsigned int hooks;
 182         unsigned short proto;
 183
 184         unsigned short family;
 185 };
 186
 187 /* Furniture shopping... */
 188 struct xt_table {
 189         struct list_head list;
 190
 191         /* What hooks you will enter on */
 192         unsigned int valid_hooks;
 193
 194         /* Man behind the curtain... */
 195         struct xt_table_info *private;
 196
 197         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 198         struct module *me;
 199
 200         u_int8_t af;            /* address/protocol family */
 201         int priority;           /* hook order */
 202
 203         /* called when table is needed in the given netns */
 204         int (*table_init)(struct net *net);
 205
 206         /* A unique name... */
 207         const char name[XT_TABLE_MAXNAMELEN];
 208 };
 209
 210 #include <linux/netfilter_ipv4.h>
 211
 212 /* The table itself */
 213 struct xt_table_info {
 214         /* Size per table */
 215         unsigned int size;
 216         /* Number of entries: FIXME. --RR */
 217         unsigned int number;
 218         /* Initial number of entries. Needed for module usage count */
 219         unsigned int initial_entries;
 220
 221         /* Entry points and underflows */
 222         unsigned int hook_entry[NF_INET_NUMHOOKS];
 223         unsigned int underflow[NF_INET_NUMHOOKS];
 224
 225         /*
 226          * Number of user chains. Since tables cannot have loops, at most
 227          * @stacksize jumps (number of user chains) can possibly be made.
 228          */
 229         unsigned int stacksize;
 230         void ***jumpstack;
 231
 232         unsigned char entries[0] __aligned(8);
 233 };
 234
 235 int xt_register_target(struct xt_target *target);
 236 void xt_unregister_target(struct xt_target *target);
 237 int xt_register_targets(struct xt_target *target, unsigned int n);
 238 void xt_unregister_targets(struct xt_target *target, unsigned int n);
 239
 240 int xt_register_match(struct xt_match *target);
 241 void xt_unregister_match(struct xt_match *target);
 242 int xt_register_matches(struct xt_match *match, unsigned int n);
 243 void xt_unregister_matches(struct xt_match *match, unsigned int n);
 244
 245 int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
 246                    bool inv_proto);
 247 int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
 248                     bool inv_proto);
 249
 250 struct xt_table *xt_register_table(struct net *net,
 251                                    const struct xt_table *table,
 252                                    struct xt_table_info *bootstrap,
 253                                    struct xt_table_info *newinfo);
 254 void *xt_unregister_table(struct xt_table *table);
 255
 256 struct xt_table_info *xt_replace_table(struct xt_table *table,
 257                                        unsigned int num_counters,
 258                                        struct xt_table_info *newinfo,
 259                                        int *error);
 260
 261 struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
 262 struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
 263 struct xt_match *xt_request_find_match(u8 af, const char *name, u8 revision);
 264 struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision);
 265 int xt_find_revision(u8 af, const char *name, u8 revision, int target,
 266                      int *err);
 267
 268 struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 269                                     const char *name);
 270 void xt_table_unlock(struct xt_table *t);
 271
 272 int xt_proto_init(struct net *net, u_int8_t af);
 273 void xt_proto_fini(struct net *net, u_int8_t af);
 274
 275 struct xt_table_info *xt_alloc_table_info(unsigned int size);
 276 void xt_free_table_info(struct xt_table_info *info);
 277
 278 /**
 279  * xt_recseq - recursive seqcount for netfilter use
 280  *
 281  * Packet processing changes the seqcount only if no recursion happened
 282  * get_counters() can use read_seqcount_begin()/read_seqcount_retry(),
 283  * because we use the normal seqcount convention :
 284  * Low order bit set to 1 if a writer is active.
 285  */
 286 DECLARE_PER_CPU(seqcount_t, xt_recseq);
 287
 288 /* xt_tee_enabled - true if x_tables needs to handle reentrancy
 289  *
 290  * Enabled if current ip(6)tables ruleset has at least one -j TEE rule.
 291  */
 292 extern struct static_key xt_tee_enabled;
 293
 294 /**
 295  * xt_write_recseq_begin - start of a write section
 296  *
 297  * Begin packet processing : all readers must wait the end
 298  * 1) Must be called with preemption disabled
 299  * 2) softirqs must be disabled too (or we should use this_cpu_add())
 300  * Returns :
 301  *  1 if no recursion on this cpu
 302  *  0 if recursion detected
 303  */
 304 static inline unsigned int xt_write_recseq_begin(void)
 305 {
 306         unsigned int addend;
 307
 308         /*
 309          * Low order bit of sequence is set if we already
 310          * called xt_write_recseq_begin().
 311          */
 312         addend = (__this_cpu_read(xt_recseq.sequence) + 1) & 1;
 313
 314         /*
 315          * This is kind of a write_seqcount_begin(), but addend is 0 or 1
 316          * We dont check addend value to avoid a test and conditional jump,
 317          * since addend is most likely 1
 318          */
 319         __this_cpu_add(xt_recseq.sequence, addend);
 320         smp_wmb();
 321
 322         return addend;
 323 }
 324
 325 /**
 326  * xt_write_recseq_end - end of a write section
 327  * @addend: return value from previous xt_write_recseq_begin()
 328  *
 329  * End packet processing : all readers can proceed
 330  * 1) Must be called with preemption disabled
 331  * 2) softirqs must be disabled too (or we should use this_cpu_add())
 332  */
 333 static inline void xt_write_recseq_end(unsigned int addend)
 334 {
 335         /* this is kind of a write_seqcount_end(), but addend is 0 or 1 */
 336         smp_wmb();
 337         __this_cpu_add(xt_recseq.sequence, addend);
 338 }
 339
 340 /*
 341  * This helper is performance critical and must be inlined
 342  */
 343 static inline unsigned long ifname_compare_aligned(const char *_a,
 344                                                    const char *_b,
 345                                                    const char *_mask)
 346 {
 347         const unsigned long *a = (const unsigned long *)_a;
 348         const unsigned long *b = (const unsigned long *)_b;
 349         const unsigned long *mask = (const unsigned long *)_mask;
 350         unsigned long ret;
 351
 352         ret = (a[0] ^ b[0]) & mask[0];
 353         if (IFNAMSIZ > sizeof(unsigned long))
 354                 ret |= (a[1] ^ b[1]) & mask[1];
 355         if (IFNAMSIZ > 2 * sizeof(unsigned long))
 356                 ret |= (a[2] ^ b[2]) & mask[2];
 357         if (IFNAMSIZ > 3 * sizeof(unsigned long))
 358                 ret |= (a[3] ^ b[3]) & mask[3];
 359         BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
 360         return ret;
 361 }
 362
 363
 364 /* On SMP, ip(6)t_entry->counters.pcnt holds address of the
 365  * real (percpu) counter.  On !SMP, its just the packet count,
 366  * so nothing needs to be done there.
 367  *
 368  * xt_percpu_counter_alloc returns the address of the percpu
 369  * counter, or 0 on !SMP. We force an alignment of 16 bytes
 370  * so that bytes/packets share a common cache line.
 371  *
 372  * Hence caller must use IS_ERR_VALUE to check for error, this
 373  * allows us to return 0 for single core systems without forcing
 374  * callers to deal with SMP vs. NONSMP issues.
 375  */
 376 static inline u64 xt_percpu_counter_alloc(void)
 377 {
 378         if (nr_cpu_ids > 1) {
 379                 void __percpu *res = __alloc_percpu(sizeof(struct xt_counters),
 380                                                     sizeof(struct xt_counters));
 381
 382                 if (res == NULL)
 383                         return (u64) -ENOMEM;
 384
 385                 return (u64) (__force unsigned long) res;
 386         }
 387
 388         return 0;
 389 }
 390 static inline void xt_percpu_counter_free(u64 pcnt)
 391 {
 392         if (nr_cpu_ids > 1)
 393                 free_percpu((void __percpu *) (unsigned long) pcnt);
 394 }
 395
 396 static inline struct xt_counters *
 397 xt_get_this_cpu_counter(struct xt_counters *cnt)
 398 {
 399         if (nr_cpu_ids > 1)
 400                 return this_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt);
 401
 402         return cnt;
 403 }
 404
 405 static inline struct xt_counters *
 406 xt_get_per_cpu_counter(struct xt_counters *cnt, unsigned int cpu)
 407 {
 408         if (nr_cpu_ids > 1)
 409                 return per_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt, cpu);
 410
 411         return cnt;
 412 }
 413
 414 struct nf_hook_ops *xt_hook_ops_alloc(const struct xt_table *, nf_hookfn *);
 415
 416 #ifdef CONFIG_COMPAT
 417 #include <net/compat.h>
 418
 419 struct compat_xt_entry_match {
 420         union {
 421                 struct {
 422                         u_int16_t match_size;
 423                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 424                         u_int8_t revision;
 425                 } user;
 426                 struct {
 427                         u_int16_t match_size;
 428                         compat_uptr_t match;
 429                 } kernel;
 430                 u_int16_t match_size;
 431         } u;
 432         unsigned char data[0];
 433 };
 434
 435 struct compat_xt_entry_target {
 436         union {
 437                 struct {
 438                         u_int16_t target_size;
 439                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 440                         u_int8_t revision;
 441                 } user;
 442                 struct {
 443                         u_int16_t target_size;
 444                         compat_uptr_t target;
 445                 } kernel;
 446                 u_int16_t target_size;
 447         } u;
 448         unsigned char data[0];
 449 };
 450
 451 /* FIXME: this works only on 32 bit tasks
 452  * need to change whole approach in order to calculate align as function of
 453  * current task alignment */
 454
 455 struct compat_xt_counters {
 456         compat_u64 pcnt, bcnt;                  /* Packet and byte counters */
 457 };
 458
 459 struct compat_xt_counters_info {
 460         char name[XT_TABLE_MAXNAMELEN];
 461         compat_uint_t num_counters;
 462         struct compat_xt_counters counters[0];
 463 };
 464
 465 struct _compat_xt_align {
 466         __u8 u8;
 467         __u16 u16;
 468         __u32 u32;
 469         compat_u64 u64;
 470 };
 471
 472 #define COMPAT_XT_ALIGN(s) __ALIGN_KERNEL((s), __alignof__(struct _compat_xt_align))
 473
 474 void xt_compat_lock(u_int8_t af);
 475 void xt_compat_unlock(u_int8_t af);
 476
 477 int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta);
 478 void xt_compat_flush_offsets(u_int8_t af);
 479 void xt_compat_init_offsets(u_int8_t af, unsigned int number);
 480 int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 481
 482 int xt_compat_match_offset(const struct xt_match *match);
 483 int xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
 484                               unsigned int *size);
 485 int xt_compat_match_to_user(const struct xt_entry_match *m,
 486                             void __user **dstptr, unsigned int *size);
 487
 488 int xt_compat_target_offset(const struct xt_target *target);
 489 void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
 490                                 unsigned int *size);
 491 int xt_compat_target_to_user(const struct xt_entry_target *t,
 492                              void __user **dstptr, unsigned int *size);
 493
 494 #endif /* CONFIG_COMPAT */
 495 #endif /* _X_TABLES_H */