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 enum nf_inet_hooks {
  43         NF_INET_PRE_ROUTING,
  44         NF_INET_LOCAL_IN,
  45         NF_INET_FORWARD,
  46         NF_INET_LOCAL_OUT,
  47         NF_INET_POST_ROUTING,
  48         NF_INET_NUMHOOKS
  49 };
  50
  51 #ifdef __KERNEL__
  52 #ifdef CONFIG_NETFILTER
  53
  54 extern void netfilter_init(void);
  55
  56 /* Largest hook number + 1 */
  57 #define NF_MAX_HOOKS 8
  58
  59 struct sk_buff;
  60 struct net_device;
  61
  62 typedef unsigned int nf_hookfn(unsigned int hooknum,
  63                                struct sk_buff *skb,
  64                                const struct net_device *in,
  65                                const struct net_device *out,
  66                                int (*okfn)(struct sk_buff *));
  67
  68 struct nf_hook_ops
  69 {
  70         struct list_head list;
  71
  72         /* User fills in from here down. */
  73         nf_hookfn *hook;
  74         struct module *owner;
  75         int pf;
  76         int hooknum;
  77         /* Hooks are ordered in ascending priority. */
  78         int priority;
  79 };
  80
  81 struct nf_sockopt_ops
  82 {
  83         struct list_head list;
  84
  85         int pf;
  86
  87         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  88         int set_optmin;
  89         int set_optmax;
  90         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  91         int (*compat_set)(struct sock *sk, int optval,
  92                         void __user *user, unsigned int len);
  93
  94         int get_optmin;
  95         int get_optmax;
  96         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  97         int (*compat_get)(struct sock *sk, int optval,
  98                         void __user *user, int *len);
  99
 100         /* Use the module struct to lock set/get code in place */
 101         struct module *owner;
 102 };
 103
 104 /* Each queued (to userspace) skbuff has one of these. */
 105 struct nf_info
 106 {
 107         /* The ops struct which sent us to userspace. */
 108         struct nf_hook_ops *elem;
 109
 110         /* If we're sent to userspace, this keeps housekeeping info */
 111         int pf;
 112         unsigned int hook;
 113         struct net_device *indev, *outdev;
 114         int (*okfn)(struct sk_buff *);
 115 };
 116
 117 /* Function to register/unregister hook points. */
 118 int nf_register_hook(struct nf_hook_ops *reg);
 119 void nf_unregister_hook(struct nf_hook_ops *reg);
 120 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 121 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 122
 123 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 124    need to check permissions yourself! */
 125 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 126 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 127
 128 #ifdef CONFIG_SYSCTL
 129 /* Sysctl registration */
 130 struct ctl_table_header *nf_register_sysctl_table(struct ctl_table *path,
 131                                                   struct ctl_table *table);
 132 void nf_unregister_sysctl_table(struct ctl_table_header *header,
 133                                 struct ctl_table *table);
 134 extern struct ctl_table nf_net_netfilter_sysctl_path[];
 135 extern struct ctl_table nf_net_ipv4_netfilter_sysctl_path[];
 136 #endif /* CONFIG_SYSCTL */
 137
 138 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 139
 140 /* those NF_LOG_* defines and struct nf_loginfo are legacy definitios that will
 141  * disappear once iptables is replaced with pkttables.  Please DO NOT use them
 142  * for any new code! */
 143 #define NF_LOG_TCPSEQ           0x01    /* Log TCP sequence numbers */
 144 #define NF_LOG_TCPOPT           0x02    /* Log TCP options */
 145 #define NF_LOG_IPOPT            0x04    /* Log IP options */
 146 #define NF_LOG_UID              0x08    /* Log UID owning local socket */
 147 #define NF_LOG_MASK             0x0f
 148
 149 #define NF_LOG_TYPE_LOG         0x01
 150 #define NF_LOG_TYPE_ULOG        0x02
 151
 152 struct nf_loginfo {
 153         u_int8_t type;
 154         union {
 155                 struct {
 156                         u_int32_t copy_len;
 157                         u_int16_t group;
 158                         u_int16_t qthreshold;
 159                 } ulog;
 160                 struct {
 161                         u_int8_t level;
 162                         u_int8_t logflags;
 163                 } log;
 164         } u;
 165 };
 166
 167 typedef void nf_logfn(unsigned int pf,
 168                       unsigned int hooknum,
 169                       const struct sk_buff *skb,
 170                       const struct net_device *in,
 171                       const struct net_device *out,
 172                       const struct nf_loginfo *li,
 173                       const char *prefix);
 174
 175 struct nf_logger {
 176         struct module   *me;
 177         nf_logfn        *logfn;
 178         char            *name;
 179 };
 180
 181 /* Function to register/unregister log function. */
 182 int nf_log_register(int pf, struct nf_logger *logger);
 183 void nf_log_unregister(struct nf_logger *logger);
 184 void nf_log_unregister_pf(int pf);
 185
 186 /* Calls the registered backend logging function */
 187 void nf_log_packet(int pf,
 188                    unsigned int hooknum,
 189                    const struct sk_buff *skb,
 190                    const struct net_device *in,
 191                    const struct net_device *out,
 192                    struct nf_loginfo *li,
 193                    const char *fmt, ...);
 194
 195 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 196                  struct net_device *indev, struct net_device *outdev,
 197                  int (*okfn)(struct sk_buff *), int thresh);
 198
 199 /**
 200  *      nf_hook_thresh - call a netfilter hook
 201  *
 202  *      Returns 1 if the hook has allowed the packet to pass.  The function
 203  *      okfn must be invoked by the caller in this case.  Any other return
 204  *      value indicates the packet has been consumed by the hook.
 205  */
 206 static inline int nf_hook_thresh(int pf, unsigned int hook,
 207                                  struct sk_buff *skb,
 208                                  struct net_device *indev,
 209                                  struct net_device *outdev,
 210                                  int (*okfn)(struct sk_buff *), int thresh,
 211                                  int cond)
 212 {
 213         if (!cond)
 214                 return 1;
 215 #ifndef CONFIG_NETFILTER_DEBUG
 216         if (list_empty(&nf_hooks[pf][hook]))
 217                 return 1;
 218 #endif
 219         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 220 }
 221
 222 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 223                           struct net_device *indev, struct net_device *outdev,
 224                           int (*okfn)(struct sk_buff *))
 225 {
 226         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 227 }
 228
 229 /* Activate hook; either okfn or kfree_skb called, unless a hook
 230    returns NF_STOLEN (in which case, it's up to the hook to deal with
 231    the consequences).
 232
 233    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 234    accepted.
 235 */
 236
 237 /* RR:
 238    > I don't want nf_hook to return anything because people might forget
 239    > about async and trust the return value to mean "packet was ok".
 240
 241    AK:
 242    Just document it clearly, then you can expect some sense from kernel
 243    coders :)
 244 */
 245
 246 /* This is gross, but inline doesn't cut it for avoiding the function
 247    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 248
 249 /* HX: It's slightly less gross now. */
 250
 251 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 252 ({int __ret;                                                                   \
 253 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 254         __ret = (okfn)(skb);                                                   \
 255 __ret;})
 256
 257 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 258 ({int __ret;                                                                   \
 259 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 260         __ret = (okfn)(skb);                                                   \
 261 __ret;})
 262
 263 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 264         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 265
 266 /* Call setsockopt() */
 267 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 268                   int len);
 269 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 270                   int *len);
 271
 272 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 273                 char __user *opt, int len);
 274 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 275                 char __user *opt, int *len);
 276
 277 /* Packet queuing */
 278 struct nf_queue_handler {
 279         int (*outfn)(struct sk_buff *skb, struct nf_info *info,
 280                      unsigned int queuenum, void *data);
 281         void *data;
 282         char *name;
 283 };
 284 extern int nf_register_queue_handler(int pf,
 285                                      struct nf_queue_handler *qh);
 286 extern int nf_unregister_queue_handler(int pf,
 287                                        struct nf_queue_handler *qh);
 288 extern void nf_unregister_queue_handlers(struct nf_queue_handler *qh);
 289 extern void nf_reinject(struct sk_buff *skb,
 290                         struct nf_info *info,
 291                         unsigned int verdict);
 292
 293 /* FIXME: Before cache is ever used, this must be implemented for real. */
 294 extern void nf_invalidate_cache(int pf);
 295
 296 /* Call this before modifying an existing packet: ensures it is
 297    modifiable and linear to the point you care about (writable_len).
 298    Returns true or false. */
 299 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 300
 301 static inline void nf_csum_replace4(__sum16 *sum, __be32 from, __be32 to)
 302 {
 303         __be32 diff[] = { ~from, to };
 304
 305         *sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
 306 }
 307
 308 static inline void nf_csum_replace2(__sum16 *sum, __be16 from, __be16 to)
 309 {
 310         nf_csum_replace4(sum, (__force __be32)from, (__force __be32)to);
 311 }
 312
 313 extern void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 314                                       __be32 from, __be32 to, int pseudohdr);
 315
 316 static inline void nf_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
 317                                       __be16 from, __be16 to, int pseudohdr)
 318 {
 319         nf_proto_csum_replace4(sum, skb, (__force __be32)from,
 320                                 (__force __be32)to, pseudohdr);
 321 }
 322
 323 struct nf_afinfo {
 324         unsigned short  family;
 325         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 326                                     unsigned int dataoff, u_int8_t protocol);
 327         void            (*saveroute)(const struct sk_buff *skb,
 328                                      struct nf_info *info);
 329         int             (*reroute)(struct sk_buff *skb,
 330                                    const struct nf_info *info);
 331         int             route_key_size;
 332 };
 333
 334 extern struct nf_afinfo *nf_afinfo[];
 335 static inline struct nf_afinfo *nf_get_afinfo(unsigned short family)
 336 {
 337         return rcu_dereference(nf_afinfo[family]);
 338 }
 339
 340 static inline __sum16
 341 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 342             u_int8_t protocol, unsigned short family)
 343 {
 344         struct nf_afinfo *afinfo;
 345         __sum16 csum = 0;
 346
 347         rcu_read_lock();
 348         afinfo = nf_get_afinfo(family);
 349         if (afinfo)
 350                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 351         rcu_read_unlock();
 352         return csum;
 353 }
 354
 355 extern int nf_register_afinfo(struct nf_afinfo *afinfo);
 356 extern void nf_unregister_afinfo(struct nf_afinfo *afinfo);
 357
 358 #define nf_info_reroute(x) ((void *)x + sizeof(struct nf_info))
 359
 360 #include <net/flow.h>
 361 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 362
 363 static inline void
 364 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 365 {
 366 #if defined(CONFIG_IP_NF_NAT_NEEDED) || defined(CONFIG_NF_NAT_NEEDED)
 367         void (*decodefn)(struct sk_buff *, struct flowi *);
 368
 369         if (family == AF_INET && (decodefn = ip_nat_decode_session) != NULL)
 370                 decodefn(skb, fl);
 371 #endif
 372 }
 373
 374 #ifdef CONFIG_PROC_FS
 375 #include <linux/proc_fs.h>
 376 extern struct proc_dir_entry *proc_net_netfilter;
 377 #endif
 378
 379 #else /* !CONFIG_NETFILTER */
 380 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 381 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 382 static inline int nf_hook_thresh(int pf, unsigned int hook,
 383                                  struct sk_buff *skb,
 384                                  struct net_device *indev,
 385                                  struct net_device *outdev,
 386                                  int (*okfn)(struct sk_buff *), int thresh,
 387                                  int cond)
 388 {
 389         return okfn(skb);
 390 }
 391 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 392                           struct net_device *indev, struct net_device *outdev,
 393                           int (*okfn)(struct sk_buff *))
 394 {
 395         return 1;
 396 }
 397 struct flowi;
 398 static inline void
 399 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 400 #endif /*CONFIG_NETFILTER*/
 401
 402 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 403 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 404 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 405 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 406 #else
 407 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 408 #endif
 409
 410 #endif /*__KERNEL__*/
 411 #endif /*__LINUX_NETFILTER_H*/