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