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 <linux/netfilter.h>
   8 #include <uapi/linux/netfilter/x_tables.h>
   9
  10 /* Test a struct->invflags and a boolean for inequality */
  11 #define NF_INVF(ptr, flag, boolean)                                     \
  12         ((boolean) ^ !!((ptr)->invflags & (flag)))
  13
  14 /**
  15  * struct xt_action_param - parameters for matches/targets
  16  *
  17  * @match:      the match extension
  18  * @target:     the target extension
  19  * @matchinfo:  per-match data
  20  * @targetinfo: per-target data
  21  * @state:      pointer to hook state this packet came from
  22  * @fragoff:    packet is a fragment, this is the data offset
  23  * @thoff:      position of transport header relative to skb->data
  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         const struct nf_hook_state *state;
  38         int fragoff;
  39         unsigned int thoff;
  40         bool hotdrop;
  41 };
  42
  43 static inline struct net *xt_net(const struct xt_action_param *par)
  44 {
  45         return par->state->net;
  46 }
  47
  48 static inline struct net_device *xt_in(const struct xt_action_param *par)
  49 {
  50         return par->state->in;
  51 }
  52
  53 static inline const char *xt_inname(const struct xt_action_param *par)
  54 {
  55         return par->state->in->name;
  56 }
  57
  58 static inline struct net_device *xt_out(const struct xt_action_param *par)
  59 {
  60         return par->state->out;
  61 }
  62
  63 static inline const char *xt_outname(const struct xt_action_param *par)
  64 {
  65         return par->state->out->name;
  66 }
  67
  68 static inline unsigned int xt_hooknum(const struct xt_action_param *par)
  69 {
  70         return par->state->hook;
  71 }
  72
  73 static inline u_int8_t xt_family(const struct xt_action_param *par)
  74 {
  75         return par->state->pf;
  76 }
  77
  78 /**
  79  * struct xt_mtchk_param - parameters for match extensions'
  80  * checkentry functions
  81  *
  82  * @net:        network namespace through which the check was invoked
  83  * @table:      table the rule is tried to be inserted into
  84  * @entryinfo:  the family-specific rule data
  85  *              (struct ipt_ip, ip6t_ip, arpt_arp or (note) ebt_entry)
  86  * @match:      struct xt_match through which this function was invoked
  87  * @matchinfo:  per-match data
  88  * @hook_mask:  via which hooks the new rule is reachable
  89  * Other fields as above.
  90  */
  91 struct xt_mtchk_param {
  92         struct net *net;
  93         const char *table;
  94         const void *entryinfo;
  95         const struct xt_match *match;
  96         void *matchinfo;
  97         unsigned int hook_mask;
  98         u_int8_t family;
  99         bool nft_compat;
 100 };
 101
 102 /**
 103  * struct xt_mdtor_param - match destructor parameters
 104  * Fields as above.
 105  */
 106 struct xt_mtdtor_param {
 107         struct net *net;
 108         const struct xt_match *match;
 109         void *matchinfo;
 110         u_int8_t family;
 111 };
 112
 113 /**
 114  * struct xt_tgchk_param - parameters for target extensions'
 115  * checkentry functions
 116  *
 117  * @entryinfo:  the family-specific rule data
 118  *              (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
 119  *
 120  * Other fields see above.
 121  */
 122 struct xt_tgchk_param {
 123         struct net *net;
 124         const char *table;
 125         const void *entryinfo;
 126         const struct xt_target *target;
 127         void *targinfo;
 128         unsigned int hook_mask;
 129         u_int8_t family;
 130         bool nft_compat;
 131 };
 132
 133 /* Target destructor parameters */
 134 struct xt_tgdtor_param {
 135         struct net *net;
 136         const struct xt_target *target;
 137         void *targinfo;
 138         u_int8_t family;
 139 };
 140
 141 struct xt_match {
 142         struct list_head list;
 143
 144         const char name[XT_EXTENSION_MAXNAMELEN];
 145         u_int8_t revision;
 146
 147         /* Return true or false: return FALSE and set *hotdrop = 1 to
 148            force immediate packet drop. */
 149         /* Arguments changed since 2.6.9, as this must now handle
 150            non-linear skb, using skb_header_pointer and
 151            skb_ip_make_writable. */
 152         bool (*match)(const struct sk_buff *skb,
 153                       struct xt_action_param *);
 154
 155         /* Called when user tries to insert an entry of this type. */
 156         int (*checkentry)(const struct xt_mtchk_param *);
 157
 158         /* Called when entry of this type deleted. */
 159         void (*destroy)(const struct xt_mtdtor_param *);
 160 #ifdef CONFIG_COMPAT
 161         /* Called when userspace align differs from kernel space one */
 162         void (*compat_from_user)(void *dst, const void *src);
 163         int (*compat_to_user)(void __user *dst, const void *src);
 164 #endif
 165         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 166         struct module *me;
 167
 168         const char *table;
 169         unsigned int matchsize;
 170         unsigned int usersize;
 171 #ifdef CONFIG_COMPAT
 172         unsigned int compatsize;
 173 #endif
 174         unsigned int hooks;
 175         unsigned short proto;
 176
 177         unsigned short family;
 178 };
 179
 180 /* Registration hooks for targets. */
 181 struct xt_target {
 182         struct list_head list;
 183
 184         const char name[XT_EXTENSION_MAXNAMELEN];
 185         u_int8_t revision;
 186
 187         /* Returns verdict. Argument order changed since 2.6.9, as this
 188            must now handle non-linear skbs, using skb_copy_bits and
 189            skb_ip_make_writable. */
 190         unsigned int (*target)(struct sk_buff *skb,
 191                                const struct xt_action_param *);
 192
 193         /* Called when user tries to insert an entry of this type:
 194            hook_mask is a bitmask of hooks from which it can be
 195            called. */
 196         /* Should return 0 on success or an error code otherwise (-Exxxx). */
 197         int (*checkentry)(const struct xt_tgchk_param *);
 198
 199         /* Called when entry of this type deleted. */
 200         void (*destroy)(const struct xt_tgdtor_param *);
 201 #ifdef CONFIG_COMPAT
 202         /* Called when userspace align differs from kernel space one */
 203         void (*compat_from_user)(void *dst, const void *src);
 204         int (*compat_to_user)(void __user *dst, const void *src);
 205 #endif
 206         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 207         struct module *me;
 208
 209         const char *table;
 210         unsigned int targetsize;
 211         unsigned int usersize;
 212 #ifdef CONFIG_COMPAT
 213         unsigned int compatsize;
 214 #endif
 215         unsigned int hooks;
 216         unsigned short proto;
 217
 218         unsigned short family;
 219 };
 220
 221 /* Furniture shopping... */
 222 struct xt_table {
 223         struct list_head list;
 224
 225         /* What hooks you will enter on */
 226         unsigned int valid_hooks;
 227
 228         /* Man behind the curtain... */
 229         struct xt_table_info *private;
 230
 231         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 232         struct module *me;
 233
 234         u_int8_t af;            /* address/protocol family */
 235         int priority;           /* hook order */
 236
 237         /* called when table is needed in the given netns */
 238         int (*table_init)(struct net *net);
 239
 240         /* A unique name... */
 241         const char name[XT_TABLE_MAXNAMELEN];
 242 };
 243
 244 #include <linux/netfilter_ipv4.h>
 245
 246 /* The table itself */
 247 struct xt_table_info {
 248         /* Size per table */
 249         unsigned int size;
 250         /* Number of entries: FIXME. --RR */
 251         unsigned int number;
 252         /* Initial number of entries. Needed for module usage count */
 253         unsigned int initial_entries;
 254
 255         /* Entry points and underflows */
 256         unsigned int hook_entry[NF_INET_NUMHOOKS];
 257         unsigned int underflow[NF_INET_NUMHOOKS];
 258
 259         /*
 260          * Number of user chains. Since tables cannot have loops, at most
 261          * @stacksize jumps (number of user chains) can possibly be made.
 262          */
 263         unsigned int stacksize;
 264         void ***jumpstack;
 265
 266         unsigned char entries[0] __aligned(8);
 267 };
 268
 269 int xt_register_target(struct xt_target *target);
 270 void xt_unregister_target(struct xt_target *target);
 271 int xt_register_targets(struct xt_target *target, unsigned int n);
 272 void xt_unregister_targets(struct xt_target *target, unsigned int n);
 273
 274 int xt_register_match(struct xt_match *target);
 275 void xt_unregister_match(struct xt_match *target);
 276 int xt_register_matches(struct xt_match *match, unsigned int n);
 277 void xt_unregister_matches(struct xt_match *match, unsigned int n);
 278
 279 int xt_check_entry_offsets(const void *base, const char *elems,
 280                            unsigned int target_offset,
 281                            unsigned int next_offset);
 282
 283 unsigned int *xt_alloc_entry_offsets(unsigned int size);
 284 bool xt_find_jump_offset(const unsigned int *offsets,
 285                          unsigned int target, unsigned int size);
 286
 287 int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
 288                    bool inv_proto);
 289 int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
 290                     bool inv_proto);
 291
 292 int xt_match_to_user(const struct xt_entry_match *m,
 293                      struct xt_entry_match __user *u);
 294 int xt_target_to_user(const struct xt_entry_target *t,
 295                       struct xt_entry_target __user *u);
 296 int xt_data_to_user(void __user *dst, const void *src,
 297                     int usersize, int size, int aligned_size);
 298
 299 void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
 300                                  struct xt_counters_info *info, bool compat);
 301
 302 struct xt_table *xt_register_table(struct net *net,
 303                                    const struct xt_table *table,
 304                                    struct xt_table_info *bootstrap,
 305                                    struct xt_table_info *newinfo);
 306 void *xt_unregister_table(struct xt_table *table);
 307
 308 struct xt_table_info *xt_replace_table(struct xt_table *table,
 309                                        unsigned int num_counters,
 310                                        struct xt_table_info *newinfo,
 311                                        int *error);
 312
 313 struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
 314 struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
 315 struct xt_match *xt_request_find_match(u8 af, const char *name, u8 revision);
 316 struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision);
 317 int xt_find_revision(u8 af, const char *name, u8 revision, int target,
 318                      int *err);
 319
 320 struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 321                                     const char *name);
 322 void xt_table_unlock(struct xt_table *t);
 323
 324 int xt_proto_init(struct net *net, u_int8_t af);
 325 void xt_proto_fini(struct net *net, u_int8_t af);
 326
 327 struct xt_table_info *xt_alloc_table_info(unsigned int size);
 328 void xt_free_table_info(struct xt_table_info *info);
 329
 330 /**
 331  * xt_recseq - recursive seqcount for netfilter use
 332  *
 333  * Packet processing changes the seqcount only if no recursion happened
 334  * get_counters() can use read_seqcount_begin()/read_seqcount_retry(),
 335  * because we use the normal seqcount convention :
 336  * Low order bit set to 1 if a writer is active.
 337  */
 338 DECLARE_PER_CPU(seqcount_t, xt_recseq);
 339
 340 /* xt_tee_enabled - true if x_tables needs to handle reentrancy
 341  *
 342  * Enabled if current ip(6)tables ruleset has at least one -j TEE rule.
 343  */
 344 extern struct static_key xt_tee_enabled;
 345
 346 /**
 347  * xt_write_recseq_begin - start of a write section
 348  *
 349  * Begin packet processing : all readers must wait the end
 350  * 1) Must be called with preemption disabled
 351  * 2) softirqs must be disabled too (or we should use this_cpu_add())
 352  * Returns :
 353  *  1 if no recursion on this cpu
 354  *  0 if recursion detected
 355  */
 356 static inline unsigned int xt_write_recseq_begin(void)
 357 {
 358         unsigned int addend;
 359
 360         /*
 361          * Low order bit of sequence is set if we already
 362          * called xt_write_recseq_begin().
 363          */
 364         addend = (__this_cpu_read(xt_recseq.sequence) + 1) & 1;
 365
 366         /*
 367          * This is kind of a write_seqcount_begin(), but addend is 0 or 1
 368          * We dont check addend value to avoid a test and conditional jump,
 369          * since addend is most likely 1
 370          */
 371         __this_cpu_add(xt_recseq.sequence, addend);
 372         smp_wmb();
 373
 374         return addend;
 375 }
 376
 377 /**
 378  * xt_write_recseq_end - end of a write section
 379  * @addend: return value from previous xt_write_recseq_begin()
 380  *
 381  * End packet processing : all readers can proceed
 382  * 1) Must be called with preemption disabled
 383  * 2) softirqs must be disabled too (or we should use this_cpu_add())
 384  */
 385 static inline void xt_write_recseq_end(unsigned int addend)
 386 {
 387         /* this is kind of a write_seqcount_end(), but addend is 0 or 1 */
 388         smp_wmb();
 389         __this_cpu_add(xt_recseq.sequence, addend);
 390 }
 391
 392 /*
 393  * This helper is performance critical and must be inlined
 394  */
 395 static inline unsigned long ifname_compare_aligned(const char *_a,
 396                                                    const char *_b,
 397                                                    const char *_mask)
 398 {
 399         const unsigned long *a = (const unsigned long *)_a;
 400         const unsigned long *b = (const unsigned long *)_b;
 401         const unsigned long *mask = (const unsigned long *)_mask;
 402         unsigned long ret;
 403
 404         ret = (a[0] ^ b[0]) & mask[0];
 405         if (IFNAMSIZ > sizeof(unsigned long))
 406                 ret |= (a[1] ^ b[1]) & mask[1];
 407         if (IFNAMSIZ > 2 * sizeof(unsigned long))
 408                 ret |= (a[2] ^ b[2]) & mask[2];
 409         if (IFNAMSIZ > 3 * sizeof(unsigned long))
 410                 ret |= (a[3] ^ b[3]) & mask[3];
 411         BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
 412         return ret;
 413 }
 414
 415 struct xt_percpu_counter_alloc_state {
 416         unsigned int off;
 417         const char __percpu *mem;
 418 };
 419
 420 bool xt_percpu_counter_alloc(struct xt_percpu_counter_alloc_state *state,
 421                              struct xt_counters *counter);
 422 void xt_percpu_counter_free(struct xt_counters *cnt);
 423
 424 static inline struct xt_counters *
 425 xt_get_this_cpu_counter(struct xt_counters *cnt)
 426 {
 427         if (nr_cpu_ids > 1)
 428                 return this_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt);
 429
 430         return cnt;
 431 }
 432
 433 static inline struct xt_counters *
 434 xt_get_per_cpu_counter(struct xt_counters *cnt, unsigned int cpu)
 435 {
 436         if (nr_cpu_ids > 1)
 437                 return per_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt, cpu);
 438
 439         return cnt;
 440 }
 441
 442 struct nf_hook_ops *xt_hook_ops_alloc(const struct xt_table *, nf_hookfn *);
 443
 444 #ifdef CONFIG_COMPAT
 445 #include <net/compat.h>
 446
 447 struct compat_xt_entry_match {
 448         union {
 449                 struct {
 450                         u_int16_t match_size;
 451                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 452                         u_int8_t revision;
 453                 } user;
 454                 struct {
 455                         u_int16_t match_size;
 456                         compat_uptr_t match;
 457                 } kernel;
 458                 u_int16_t match_size;
 459         } u;
 460         unsigned char data[0];
 461 };
 462
 463 struct compat_xt_entry_target {
 464         union {
 465                 struct {
 466                         u_int16_t target_size;
 467                         char name[XT_FUNCTION_MAXNAMELEN - 1];
 468                         u_int8_t revision;
 469                 } user;
 470                 struct {
 471                         u_int16_t target_size;
 472                         compat_uptr_t target;
 473                 } kernel;
 474                 u_int16_t target_size;
 475         } u;
 476         unsigned char data[0];
 477 };
 478
 479 /* FIXME: this works only on 32 bit tasks
 480  * need to change whole approach in order to calculate align as function of
 481  * current task alignment */
 482
 483 struct compat_xt_counters {
 484         compat_u64 pcnt, bcnt;                  /* Packet and byte counters */
 485 };
 486
 487 struct compat_xt_counters_info {
 488         char name[XT_TABLE_MAXNAMELEN];
 489         compat_uint_t num_counters;
 490         struct compat_xt_counters counters[0];
 491 };
 492
 493 struct _compat_xt_align {
 494         __u8 u8;
 495         __u16 u16;
 496         __u32 u32;
 497         compat_u64 u64;
 498 };
 499
 500 #define COMPAT_XT_ALIGN(s) __ALIGN_KERNEL((s), __alignof__(struct _compat_xt_align))
 501
 502 void xt_compat_lock(u_int8_t af);
 503 void xt_compat_unlock(u_int8_t af);
 504
 505 int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta);
 506 void xt_compat_flush_offsets(u_int8_t af);
 507 void xt_compat_init_offsets(u_int8_t af, unsigned int number);
 508 int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 509
 510 int xt_compat_match_offset(const struct xt_match *match);
 511 void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
 512                               unsigned int *size);
 513 int xt_compat_match_to_user(const struct xt_entry_match *m,
 514                             void __user **dstptr, unsigned int *size);
 515
 516 int xt_compat_target_offset(const struct xt_target *target);
 517 void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
 518                                 unsigned int *size);
 519 int xt_compat_target_to_user(const struct xt_entry_target *t,
 520                              void __user **dstptr, unsigned int *size);
 521 int xt_compat_check_entry_offsets(const void *base, const char *elems,
 522                                   unsigned int target_offset,
 523                                   unsigned int next_offset);
 524
 525 #endif /* CONFIG_COMPAT */
 526 #endif /* _X_TABLES_H */