include/linux/netfilter_arp/arp_tables.h

   1 /*
   2  *      Format of an ARP firewall descriptor
   3  *
   4  *      src, tgt, src_mask, tgt_mask, arpop, arpop_mask are always stored in
   5  *      network byte order.
   6  *      flags are stored in host byte order (of course).
   7  */
   8
   9 #ifndef _ARPTABLES_H
  10 #define _ARPTABLES_H
  11
  12 #ifdef __KERNEL__
  13 #include <linux/if.h>
  14 #include <linux/types.h>
  15 #include <linux/in.h>
  16 #include <linux/if_arp.h>
  17 #include <linux/skbuff.h>
  18 #endif
  19 #include <linux/compiler.h>
  20 #include <linux/netfilter_arp.h>
  21
  22 #define ARPT_FUNCTION_MAXNAMELEN 30
  23 #define ARPT_TABLE_MAXNAMELEN 32
  24
  25 #define ARPT_DEV_ADDR_LEN_MAX 16
  26
  27 struct arpt_devaddr_info {
  28         char addr[ARPT_DEV_ADDR_LEN_MAX];
  29         char mask[ARPT_DEV_ADDR_LEN_MAX];
  30 };
  31
  32 /* Yes, Virginia, you have to zero the padding. */
  33 struct arpt_arp {
  34         /* Source and target IP addr */
  35         struct in_addr src, tgt;
  36         /* Mask for src and target IP addr */
  37         struct in_addr smsk, tmsk;
  38
  39         /* Device hw address length, src+target device addresses */
  40         u_int8_t arhln, arhln_mask;
  41         struct arpt_devaddr_info src_devaddr;
  42         struct arpt_devaddr_info tgt_devaddr;
  43
  44         /* ARP operation code. */
  45         u_int16_t arpop, arpop_mask;
  46
  47         /* ARP hardware address and protocol address format. */
  48         u_int16_t arhrd, arhrd_mask;
  49         u_int16_t arpro, arpro_mask;
  50
  51         /* The protocol address length is only accepted if it is 4
  52          * so there is no use in offering a way to do filtering on it.
  53          */
  54
  55         char iniface[IFNAMSIZ], outiface[IFNAMSIZ];
  56         unsigned char iniface_mask[IFNAMSIZ], outiface_mask[IFNAMSIZ];
  57
  58         /* Flags word */
  59         u_int8_t flags;
  60         /* Inverse flags */
  61         u_int16_t invflags;
  62 };
  63
  64 struct arpt_entry_target
  65 {
  66         union {
  67                 struct {
  68                         u_int16_t target_size;
  69
  70                         /* Used by userspace */
  71                         char name[ARPT_FUNCTION_MAXNAMELEN];
  72                 } user;
  73                 struct {
  74                         u_int16_t target_size;
  75
  76                         /* Used inside the kernel */
  77                         struct arpt_target *target;
  78                 } kernel;
  79
  80                 /* Total length */
  81                 u_int16_t target_size;
  82         } u;
  83
  84         unsigned char data[0];
  85 };
  86
  87 struct arpt_standard_target
  88 {
  89         struct arpt_entry_target target;
  90         int verdict;
  91 };
  92
  93 struct arpt_counters
  94 {
  95         u_int64_t pcnt, bcnt;                   /* Packet and byte counters */
  96 };
  97
  98 /* Values for "flag" field in struct arpt_ip (general arp structure).
  99  * No flags defined yet.
 100  */
 101 #define ARPT_F_MASK             0x00    /* All possible flag bits mask. */
 102
 103 /* Values for "inv" field in struct arpt_arp. */
 104 #define ARPT_INV_VIA_IN         0x0001  /* Invert the sense of IN IFACE. */
 105 #define ARPT_INV_VIA_OUT        0x0002  /* Invert the sense of OUT IFACE */
 106 #define ARPT_INV_SRCIP          0x0004  /* Invert the sense of SRC IP. */
 107 #define ARPT_INV_TGTIP          0x0008  /* Invert the sense of TGT IP. */
 108 #define ARPT_INV_SRCDEVADDR     0x0010  /* Invert the sense of SRC DEV ADDR. */
 109 #define ARPT_INV_TGTDEVADDR     0x0020  /* Invert the sense of TGT DEV ADDR. */
 110 #define ARPT_INV_ARPOP          0x0040  /* Invert the sense of ARP OP. */
 111 #define ARPT_INV_ARPHRD         0x0080  /* Invert the sense of ARP HRD. */
 112 #define ARPT_INV_ARPPRO         0x0100  /* Invert the sense of ARP PRO. */
 113 #define ARPT_INV_ARPHLN         0x0200  /* Invert the sense of ARP HLN. */
 114 #define ARPT_INV_MASK           0x03FF  /* All possible flag bits mask. */
 115
 116 /* This structure defines each of the firewall rules.  Consists of 3
 117    parts which are 1) general ARP header stuff 2) match specific
 118    stuff 3) the target to perform if the rule matches */
 119 struct arpt_entry
 120 {
 121         struct arpt_arp arp;
 122
 123         /* Size of arpt_entry + matches */
 124         u_int16_t target_offset;
 125         /* Size of arpt_entry + matches + target */
 126         u_int16_t next_offset;
 127
 128         /* Back pointer */
 129         unsigned int comefrom;
 130
 131         /* Packet and byte counters. */
 132         struct arpt_counters counters;
 133
 134         /* The matches (if any), then the target. */
 135         unsigned char elems[0];
 136 };
 137
 138 /*
 139  * New IP firewall options for [gs]etsockopt at the RAW IP level.
 140  * Unlike BSD Linux inherits IP options so you don't have to use a raw
 141  * socket for this. Instead we check rights in the calls.
 142  */
 143 #define ARPT_BASE_CTL           96      /* base for firewall socket options */
 144
 145 #define ARPT_SO_SET_REPLACE             (ARPT_BASE_CTL)
 146 #define ARPT_SO_SET_ADD_COUNTERS        (ARPT_BASE_CTL + 1)
 147 #define ARPT_SO_SET_MAX                 ARPT_SO_SET_ADD_COUNTERS
 148
 149 #define ARPT_SO_GET_INFO                (ARPT_BASE_CTL)
 150 #define ARPT_SO_GET_ENTRIES             (ARPT_BASE_CTL + 1)
 151 #define ARPT_SO_GET_MAX                 ARPT_SO_GET_ENTRIES
 152
 153 /* CONTINUE verdict for targets */
 154 #define ARPT_CONTINUE 0xFFFFFFFF
 155
 156 /* For standard target */
 157 #define ARPT_RETURN (-NF_REPEAT - 1)
 158
 159 /* The argument to ARPT_SO_GET_INFO */
 160 struct arpt_getinfo
 161 {
 162         /* Which table: caller fills this in. */
 163         char name[ARPT_TABLE_MAXNAMELEN];
 164
 165         /* Kernel fills these in. */
 166         /* Which hook entry points are valid: bitmask */
 167         unsigned int valid_hooks;
 168
 169         /* Hook entry points: one per netfilter hook. */
 170         unsigned int hook_entry[NF_ARP_NUMHOOKS];
 171
 172         /* Underflow points. */
 173         unsigned int underflow[NF_ARP_NUMHOOKS];
 174
 175         /* Number of entries */
 176         unsigned int num_entries;
 177
 178         /* Size of entries. */
 179         unsigned int size;
 180 };
 181
 182 /* The argument to ARPT_SO_SET_REPLACE. */
 183 struct arpt_replace
 184 {
 185         /* Which table. */
 186         char name[ARPT_TABLE_MAXNAMELEN];
 187
 188         /* Which hook entry points are valid: bitmask.  You can't
 189            change this. */
 190         unsigned int valid_hooks;
 191
 192         /* Number of entries */
 193         unsigned int num_entries;
 194
 195         /* Total size of new entries */
 196         unsigned int size;
 197
 198         /* Hook entry points. */
 199         unsigned int hook_entry[NF_ARP_NUMHOOKS];
 200
 201         /* Underflow points. */
 202         unsigned int underflow[NF_ARP_NUMHOOKS];
 203
 204         /* Information about old entries: */
 205         /* Number of counters (must be equal to current number of entries). */
 206         unsigned int num_counters;
 207         /* The old entries' counters. */
 208         struct arpt_counters __user *counters;
 209
 210         /* The entries (hang off end: not really an array). */
 211         struct arpt_entry entries[0];
 212 };
 213
 214 /* The argument to ARPT_SO_ADD_COUNTERS. */
 215 struct arpt_counters_info
 216 {
 217         /* Which table. */
 218         char name[ARPT_TABLE_MAXNAMELEN];
 219
 220         unsigned int num_counters;
 221
 222         /* The counters (actually `number' of these). */
 223         struct arpt_counters counters[0];
 224 };
 225
 226 /* The argument to ARPT_SO_GET_ENTRIES. */
 227 struct arpt_get_entries
 228 {
 229         /* Which table: user fills this in. */
 230         char name[ARPT_TABLE_MAXNAMELEN];
 231
 232         /* User fills this in: total entry size. */
 233         unsigned int size;
 234
 235         /* The entries. */
 236         struct arpt_entry entrytable[0];
 237 };
 238
 239 /* Standard return verdict, or do jump. */
 240 #define ARPT_STANDARD_TARGET ""
 241 /* Error verdict. */
 242 #define ARPT_ERROR_TARGET "ERROR"
 243
 244 /* Helper functions */
 245 static __inline__ struct arpt_entry_target *arpt_get_target(struct arpt_entry *e)
 246 {
 247         return (void *)e + e->target_offset;
 248 }
 249
 250 /* fn returns 0 to continue iteration */
 251 #define ARPT_ENTRY_ITERATE(entries, size, fn, args...)          \
 252 ({                                                              \
 253         unsigned int __i;                                       \
 254         int __ret = 0;                                          \
 255         struct arpt_entry *__entry;                             \
 256                                                                 \
 257         for (__i = 0; __i < (size); __i += __entry->next_offset) { \
 258                 __entry = (void *)(entries) + __i;              \
 259                                                                 \
 260                 __ret = fn(__entry , ## args);                  \
 261                 if (__ret != 0)                                 \
 262                         break;                                  \
 263         }                                                       \
 264         __ret;                                                  \
 265 })
 266
 267 /*
 268  *      Main firewall chains definitions and global var's definitions.
 269  */
 270 #ifdef __KERNEL__
 271
 272 /* Registration hooks for targets. */
 273 struct arpt_target
 274 {
 275         struct list_head list;
 276
 277         const char name[ARPT_FUNCTION_MAXNAMELEN];
 278
 279         /* Returns verdict. */
 280         unsigned int (*target)(struct sk_buff **pskb,
 281                                unsigned int hooknum,
 282                                const struct net_device *in,
 283                                const struct net_device *out,
 284                                const void *targinfo,
 285                                void *userdata);
 286
 287         /* Called when user tries to insert an entry of this type:
 288            hook_mask is a bitmask of hooks from which it can be
 289            called. */
 290         /* Should return true or false. */
 291         int (*checkentry)(const char *tablename,
 292                           const struct arpt_entry *e,
 293                           void *targinfo,
 294                           unsigned int targinfosize,
 295                           unsigned int hook_mask);
 296
 297         /* Called when entry of this type deleted. */
 298         void (*destroy)(void *targinfo, unsigned int targinfosize);
 299
 300         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 301         struct module *me;
 302 };
 303
 304 extern int arpt_register_target(struct arpt_target *target);
 305 extern void arpt_unregister_target(struct arpt_target *target);
 306
 307 /* Furniture shopping... */
 308 struct arpt_table
 309 {
 310         struct list_head list;
 311
 312         /* A unique name... */
 313         char name[ARPT_TABLE_MAXNAMELEN];
 314
 315         /* What hooks you will enter on */
 316         unsigned int valid_hooks;
 317
 318         /* Lock for the curtain */
 319         rwlock_t lock;
 320
 321         /* Man behind the curtain... */
 322         struct arpt_table_info *private;
 323
 324         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
 325         struct module *me;
 326 };
 327
 328 extern int arpt_register_table(struct arpt_table *table,
 329                                const struct arpt_replace *repl);
 330 extern void arpt_unregister_table(struct arpt_table *table);
 331 extern unsigned int arpt_do_table(struct sk_buff **pskb,
 332                                   unsigned int hook,
 333                                   const struct net_device *in,
 334                                   const struct net_device *out,
 335                                   struct arpt_table *table,
 336                                   void *userdata);
 337
 338 #define ARPT_ALIGN(s) (((s) + (__alignof__(struct arpt_entry)-1)) & ~(__alignof__(struct arpt_entry)-1))
 339 #endif /*__KERNEL__*/
 340 #endif /* _ARPTABLES_H */