include/linux/netfilter.h

   1 #ifndef __LINUX_NETFILTER_H
   2 #define __LINUX_NETFILTER_H
   3
   4 #ifdef __KERNEL__
   5 #include <linux/init.h>
   6 #include <linux/types.h>
   7 #include <linux/skbuff.h>
   8 #include <linux/net.h>
   9 #include <linux/if.h>
  10 #include <linux/wait.h>
  11 #include <linux/list.h>
  12 #endif
  13 #include <linux/compiler.h>
  14
  15 /* Responses from hook functions. */
  16 #define NF_DROP 0
  17 #define NF_ACCEPT 1
  18 #define NF_STOLEN 2
  19 #define NF_QUEUE 3
  20 #define NF_REPEAT 4
  21 #define NF_STOP 5
  22 #define NF_MAX_VERDICT NF_STOP
  23
  24 /* we overload the higher bits for encoding auxiliary data such as the queue
  25  * number. Not nice, but better than additional function arguments. */
  26 #define NF_VERDICT_MASK 0x0000ffff
  27 #define NF_VERDICT_BITS 16
  28
  29 #define NF_VERDICT_QMASK 0xffff0000
  30 #define NF_VERDICT_QBITS 16
  31
  32 #define NF_QUEUE_NR(x) (((x << NF_VERDICT_QBITS) & NF_VERDICT_QMASK) | NF_QUEUE)
  33
  34 /* only for userspace compatibility */
  35 #ifndef __KERNEL__
  36 /* Generic cache responses from hook functions.
  37    <= 0x2000 is used for protocol-flags. */
  38 #define NFC_UNKNOWN 0x4000
  39 #define NFC_ALTERED 0x8000
  40 #endif
  41
  42 #ifdef __KERNEL__
  43 #ifdef CONFIG_NETFILTER
  44
  45 extern void netfilter_init(void);
  46
  47 /* Largest hook number + 1 */
  48 #define NF_MAX_HOOKS 8
  49
  50 struct sk_buff;
  51 struct net_device;
  52
  53 typedef unsigned int nf_hookfn(unsigned int hooknum,
  54                                struct sk_buff *skb,
  55                                const struct net_device *in,
  56                                const struct net_device *out,
  57                                int (*okfn)(struct sk_buff *));
  58
  59 struct nf_hook_ops
  60 {
  61         struct list_head list;
  62
  63         /* User fills in from here down. */
  64         nf_hookfn *hook;
  65         struct module *owner;
  66         int pf;
  67         int hooknum;
  68         /* Hooks are ordered in ascending priority. */
  69         int priority;
  70 };
  71
  72 struct nf_sockopt_ops
  73 {
  74         struct list_head list;
  75
  76         int pf;
  77
  78         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  79         int set_optmin;
  80         int set_optmax;
  81         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  82         int (*compat_set)(struct sock *sk, int optval,
  83                         void __user *user, unsigned int len);
  84
  85         int get_optmin;
  86         int get_optmax;
  87         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  88         int (*compat_get)(struct sock *sk, int optval,
  89                         void __user *user, int *len);
  90
  91         /* Use the module struct to lock set/get code in place */
  92         struct module *owner;
  93 };
  94
  95 /* Each queued (to userspace) skbuff has one of these. */
  96 struct nf_info
  97 {
  98         /* The ops struct which sent us to userspace. */
  99         struct nf_hook_ops *elem;
 100
 101         /* If we're sent to userspace, this keeps housekeeping info */
 102         int pf;
 103         unsigned int hook;
 104         struct net_device *indev, *outdev;
 105         int (*okfn)(struct sk_buff *);
 106 };
 107
 108 /* Function to register/unregister hook points. */
 109 int nf_register_hook(struct nf_hook_ops *reg);
 110 void nf_unregister_hook(struct nf_hook_ops *reg);
 111 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 112 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 113
 114 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 115    need to check permissions yourself! */
 116 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 117 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 118
 119 #ifdef CONFIG_SYSCTL
 120 /* Sysctl registration */
 121 struct ctl_table_header *nf_register_sysctl_table(struct ctl_table *path,
 122                                                   struct ctl_table *table);
 123 void nf_unregister_sysctl_table(struct ctl_table_header *header,
 124                                 struct ctl_table *table);
 125 extern struct ctl_table nf_net_netfilter_sysctl_path[];
 126 extern struct ctl_table nf_net_ipv4_netfilter_sysctl_path[];
 127 #endif /* CONFIG_SYSCTL */
 128
 129 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 130
 131 /* those NF_LOG_* defines and struct nf_loginfo are legacy definitios that will
 132  * disappear once iptables is replaced with pkttables.  Please DO NOT use them
 133  * for any new code! */
 134 #define NF_LOG_TCPSEQ           0x01    /* Log TCP sequence numbers */
 135 #define NF_LOG_TCPOPT           0x02    /* Log TCP options */
 136 #define NF_LOG_IPOPT            0x04    /* Log IP options */
 137 #define NF_LOG_UID              0x08    /* Log UID owning local socket */
 138 #define NF_LOG_MASK             0x0f
 139
 140 #define NF_LOG_TYPE_LOG         0x01
 141 #define NF_LOG_TYPE_ULOG        0x02
 142
 143 struct nf_loginfo {
 144         u_int8_t type;
 145         union {
 146                 struct {
 147                         u_int32_t copy_len;
 148                         u_int16_t group;
 149                         u_int16_t qthreshold;
 150                 } ulog;
 151                 struct {
 152                         u_int8_t level;
 153                         u_int8_t logflags;
 154                 } log;
 155         } u;
 156 };
 157
 158 typedef void nf_logfn(unsigned int pf,
 159                       unsigned int hooknum,
 160                       const struct sk_buff *skb,
 161                       const struct net_device *in,
 162                       const struct net_device *out,
 163                       const struct nf_loginfo *li,
 164                       const char *prefix);
 165
 166 struct nf_logger {
 167         struct module   *me;
 168         nf_logfn        *logfn;
 169         char            *name;
 170 };
 171
 172 /* Function to register/unregister log function. */
 173 int nf_log_register(int pf, struct nf_logger *logger);
 174 void nf_log_unregister(struct nf_logger *logger);
 175 void nf_log_unregister_pf(int pf);
 176
 177 /* Calls the registered backend logging function */
 178 void nf_log_packet(int pf,
 179                    unsigned int hooknum,
 180                    const struct sk_buff *skb,
 181                    const struct net_device *in,
 182                    const struct net_device *out,
 183                    struct nf_loginfo *li,
 184                    const char *fmt, ...);
 185
 186 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 187                  struct net_device *indev, struct net_device *outdev,
 188                  int (*okfn)(struct sk_buff *), int thresh);
 189
 190 /**
 191  *      nf_hook_thresh - call a netfilter hook
 192  *
 193  *      Returns 1 if the hook has allowed the packet to pass.  The function
 194  *      okfn must be invoked by the caller in this case.  Any other return
 195  *      value indicates the packet has been consumed by the hook.
 196  */
 197 static inline int nf_hook_thresh(int pf, unsigned int hook,
 198                                  struct sk_buff *skb,
 199                                  struct net_device *indev,
 200                                  struct net_device *outdev,
 201                                  int (*okfn)(struct sk_buff *), int thresh,
 202                                  int cond)
 203 {
 204         if (!cond)
 205                 return 1;
 206 #ifndef CONFIG_NETFILTER_DEBUG
 207         if (list_empty(&nf_hooks[pf][hook]))
 208                 return 1;
 209 #endif
 210         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 211 }
 212
 213 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 214                           struct net_device *indev, struct net_device *outdev,
 215                           int (*okfn)(struct sk_buff *))
 216 {
 217         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 218 }
 219
 220 /* Activate hook; either okfn or kfree_skb called, unless a hook
 221    returns NF_STOLEN (in which case, it's up to the hook to deal with
 222    the consequences).
 223
 224    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 225    accepted.
 226 */
 227
 228 /* RR:
 229    > I don't want nf_hook to return anything because people might forget
 230    > about async and trust the return value to mean "packet was ok".
 231
 232    AK:
 233    Just document it clearly, then you can expect some sense from kernel
 234    coders :)
 235 */
 236
 237 /* This is gross, but inline doesn't cut it for avoiding the function
 238    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 239
 240 /* HX: It's slightly less gross now. */
 241
 242 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 243 ({int __ret;                                                                   \
 244 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 245         __ret = (okfn)(skb);                                                   \
 246 __ret;})
 247
 248 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 249 ({int __ret;                                                                   \
 250 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 251         __ret = (okfn)(skb);                                                   \
 252 __ret;})
 253
 254 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 255         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 256
 257 /* Call setsockopt() */
 258 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 259                   int len);
 260 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 261                   int *len);
 262
 263 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 264                 char __user *opt, int len);
 265 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 266                 char __user *opt, int *len);
 267
 268 /* Packet queuing */
 269 struct nf_queue_handler {
 270         int (*outfn)(struct sk_buff *skb, struct nf_info *info,
 271                      unsigned int queuenum, void *data);
 272         void *data;
 273         char *name;
 274 };
 275 extern int nf_register_queue_handler(int pf,
 276                                      struct nf_queue_handler *qh);
 277 extern int nf_unregister_queue_handler(int pf,
 278                                        struct nf_queue_handler *qh);
 279 extern void nf_unregister_queue_handlers(struct nf_queue_handler *qh);
 280 extern void nf_reinject(struct sk_buff *skb,
 281                         struct nf_info *info,
 282                         unsigned int verdict);
 283
 284 /* FIXME: Before cache is ever used, this must be implemented for real. */
 285 extern void nf_invalidate_cache(int pf);
 286
 287 /* Call this before modifying an existing packet: ensures it is
 288    modifiable and linear to the point you care about (writable_len).
 289    Returns true or false. */
 290 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 291
 292 static inline void nf_csum_replace4(__sum16 *sum, __be32 from, __be32 to)
 293 {
 294         __be32 diff[] = { ~from, to };
 295
 296         *sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
 297 }
 298
 299 static inline void nf_csum_replace2(__sum16 *sum, __be16 from, __be16 to)
 300 {
 301         nf_csum_replace4(sum, (__force __be32)from, (__force __be32)to);
 302 }
 303
 304 extern void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 305                                       __be32 from, __be32 to, int pseudohdr);
 306
 307 static inline void nf_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
 308                                       __be16 from, __be16 to, int pseudohdr)
 309 {
 310         nf_proto_csum_replace4(sum, skb, (__force __be32)from,
 311                                 (__force __be32)to, pseudohdr);
 312 }
 313
 314 struct nf_afinfo {
 315         unsigned short  family;
 316         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 317                                     unsigned int dataoff, u_int8_t protocol);
 318         void            (*saveroute)(const struct sk_buff *skb,
 319                                      struct nf_info *info);
 320         int             (*reroute)(struct sk_buff *skb,
 321                                    const struct nf_info *info);
 322         int             route_key_size;
 323 };
 324
 325 extern struct nf_afinfo *nf_afinfo[];
 326 static inline struct nf_afinfo *nf_get_afinfo(unsigned short family)
 327 {
 328         return rcu_dereference(nf_afinfo[family]);
 329 }
 330
 331 static inline __sum16
 332 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 333             u_int8_t protocol, unsigned short family)
 334 {
 335         struct nf_afinfo *afinfo;
 336         __sum16 csum = 0;
 337
 338         rcu_read_lock();
 339         afinfo = nf_get_afinfo(family);
 340         if (afinfo)
 341                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 342         rcu_read_unlock();
 343         return csum;
 344 }
 345
 346 extern int nf_register_afinfo(struct nf_afinfo *afinfo);
 347 extern void nf_unregister_afinfo(struct nf_afinfo *afinfo);
 348
 349 #define nf_info_reroute(x) ((void *)x + sizeof(struct nf_info))
 350
 351 #include <net/flow.h>
 352 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 353
 354 static inline void
 355 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 356 {
 357 #if defined(CONFIG_IP_NF_NAT_NEEDED) || defined(CONFIG_NF_NAT_NEEDED)
 358         void (*decodefn)(struct sk_buff *, struct flowi *);
 359
 360         if (family == AF_INET && (decodefn = ip_nat_decode_session) != NULL)
 361                 decodefn(skb, fl);
 362 #endif
 363 }
 364
 365 #ifdef CONFIG_PROC_FS
 366 #include <linux/proc_fs.h>
 367 extern struct proc_dir_entry *proc_net_netfilter;
 368 #endif
 369
 370 #else /* !CONFIG_NETFILTER */
 371 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 372 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 373 static inline int nf_hook_thresh(int pf, unsigned int hook,
 374                                  struct sk_buff *skb,
 375                                  struct net_device *indev,
 376                                  struct net_device *outdev,
 377                                  int (*okfn)(struct sk_buff *), int thresh,
 378                                  int cond)
 379 {
 380         return okfn(skb);
 381 }
 382 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 383                           struct net_device *indev, struct net_device *outdev,
 384                           int (*okfn)(struct sk_buff *))
 385 {
 386         return 1;
 387 }
 388 struct flowi;
 389 static inline void
 390 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 391 #endif /*CONFIG_NETFILTER*/
 392
 393 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 394 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 395 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 396 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 397 #else
 398 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 399 #endif
 400
 401 #endif /*__KERNEL__*/
 402 #endif /*__LINUX_NETFILTER_H*/