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 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 121
 122 /* those NF_LOG_* defines and struct nf_loginfo are legacy definitios that will
 123  * disappear once iptables is replaced with pkttables.  Please DO NOT use them
 124  * for any new code! */
 125 #define NF_LOG_TCPSEQ           0x01    /* Log TCP sequence numbers */
 126 #define NF_LOG_TCPOPT           0x02    /* Log TCP options */
 127 #define NF_LOG_IPOPT            0x04    /* Log IP options */
 128 #define NF_LOG_UID              0x08    /* Log UID owning local socket */
 129 #define NF_LOG_MASK             0x0f
 130
 131 #define NF_LOG_TYPE_LOG         0x01
 132 #define NF_LOG_TYPE_ULOG        0x02
 133
 134 struct nf_loginfo {
 135         u_int8_t type;
 136         union {
 137                 struct {
 138                         u_int32_t copy_len;
 139                         u_int16_t group;
 140                         u_int16_t qthreshold;
 141                 } ulog;
 142                 struct {
 143                         u_int8_t level;
 144                         u_int8_t logflags;
 145                 } log;
 146         } u;
 147 };
 148
 149 typedef void nf_logfn(unsigned int pf,
 150                       unsigned int hooknum,
 151                       const struct sk_buff *skb,
 152                       const struct net_device *in,
 153                       const struct net_device *out,
 154                       const struct nf_loginfo *li,
 155                       const char *prefix);
 156
 157 struct nf_logger {
 158         struct module   *me;
 159         nf_logfn        *logfn;
 160         char            *name;
 161 };
 162
 163 /* Function to register/unregister log function. */
 164 int nf_log_register(int pf, struct nf_logger *logger);
 165 int nf_log_unregister_pf(int pf);
 166 void nf_log_unregister_logger(struct nf_logger *logger);
 167
 168 /* Calls the registered backend logging function */
 169 void nf_log_packet(int pf,
 170                    unsigned int hooknum,
 171                    const struct sk_buff *skb,
 172                    const struct net_device *in,
 173                    const struct net_device *out,
 174                    struct nf_loginfo *li,
 175                    const char *fmt, ...);
 176
 177 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
 178                  struct net_device *indev, struct net_device *outdev,
 179                  int (*okfn)(struct sk_buff *), int thresh);
 180
 181 /**
 182  *      nf_hook_thresh - call a netfilter hook
 183  *
 184  *      Returns 1 if the hook has allowed the packet to pass.  The function
 185  *      okfn must be invoked by the caller in this case.  Any other return
 186  *      value indicates the packet has been consumed by the hook.
 187  */
 188 static inline int nf_hook_thresh(int pf, unsigned int hook,
 189                                  struct sk_buff **pskb,
 190                                  struct net_device *indev,
 191                                  struct net_device *outdev,
 192                                  int (*okfn)(struct sk_buff *), int thresh,
 193                                  int cond)
 194 {
 195         if (!cond)
 196                 return 1;
 197 #ifndef CONFIG_NETFILTER_DEBUG
 198         if (list_empty(&nf_hooks[pf][hook]))
 199                 return 1;
 200 #endif
 201         return nf_hook_slow(pf, hook, pskb, indev, outdev, okfn, thresh);
 202 }
 203
 204 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff **pskb,
 205                           struct net_device *indev, struct net_device *outdev,
 206                           int (*okfn)(struct sk_buff *))
 207 {
 208         return nf_hook_thresh(pf, hook, pskb, indev, outdev, okfn, INT_MIN, 1);
 209 }
 210
 211 /* Activate hook; either okfn or kfree_skb called, unless a hook
 212    returns NF_STOLEN (in which case, it's up to the hook to deal with
 213    the consequences).
 214
 215    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 216    accepted.
 217 */
 218
 219 /* RR:
 220    > I don't want nf_hook to return anything because people might forget
 221    > about async and trust the return value to mean "packet was ok".
 222
 223    AK:
 224    Just document it clearly, then you can expect some sense from kernel
 225    coders :)
 226 */
 227
 228 /* This is gross, but inline doesn't cut it for avoiding the function
 229    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 230
 231 /* HX: It's slightly less gross now. */
 232
 233 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 234 ({int __ret;                                                                   \
 235 if ((__ret=nf_hook_thresh(pf, hook, &(skb), indev, outdev, okfn, thresh, 1)) == 1)\
 236         __ret = (okfn)(skb);                                                   \
 237 __ret;})
 238
 239 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 240 ({int __ret;                                                                   \
 241 if ((__ret=nf_hook_thresh(pf, hook, &(skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 242         __ret = (okfn)(skb);                                                   \
 243 __ret;})
 244
 245 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 246         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 247
 248 /* Call setsockopt() */
 249 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 250                   int len);
 251 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 252                   int *len);
 253
 254 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 255                 char __user *opt, int len);
 256 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 257                 char __user *opt, int *len);
 258
 259 /* Packet queuing */
 260 struct nf_queue_handler {
 261         int (*outfn)(struct sk_buff *skb, struct nf_info *info,
 262                      unsigned int queuenum, void *data);
 263         void *data;
 264         char *name;
 265 };
 266 extern int nf_register_queue_handler(int pf,
 267                                      struct nf_queue_handler *qh);
 268 extern int nf_unregister_queue_handler(int pf);
 269 extern void nf_unregister_queue_handlers(struct nf_queue_handler *qh);
 270 extern void nf_reinject(struct sk_buff *skb,
 271                         struct nf_info *info,
 272                         unsigned int verdict);
 273
 274 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 275 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 276
 277 /* FIXME: Before cache is ever used, this must be implemented for real. */
 278 extern void nf_invalidate_cache(int pf);
 279
 280 /* Call this before modifying an existing packet: ensures it is
 281    modifiable and linear to the point you care about (writable_len).
 282    Returns true or false. */
 283 extern int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len);
 284
 285 struct nf_afinfo {
 286         unsigned short  family;
 287         unsigned int    (*checksum)(struct sk_buff *skb, unsigned int hook,
 288                                     unsigned int dataoff, u_int8_t protocol);
 289         void            (*saveroute)(const struct sk_buff *skb,
 290                                      struct nf_info *info);
 291         int             (*reroute)(struct sk_buff **skb,
 292                                    const struct nf_info *info);
 293         int             route_key_size;
 294 };
 295
 296 extern struct nf_afinfo *nf_afinfo[];
 297 static inline struct nf_afinfo *nf_get_afinfo(unsigned short family)
 298 {
 299         return rcu_dereference(nf_afinfo[family]);
 300 }
 301
 302 static inline unsigned int
 303 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 304             u_int8_t protocol, unsigned short family)
 305 {
 306         struct nf_afinfo *afinfo;
 307         unsigned int csum = 0;
 308
 309         rcu_read_lock();
 310         afinfo = nf_get_afinfo(family);
 311         if (afinfo)
 312                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 313         rcu_read_unlock();
 314         return csum;
 315 }
 316
 317 extern int nf_register_afinfo(struct nf_afinfo *afinfo);
 318 extern void nf_unregister_afinfo(struct nf_afinfo *afinfo);
 319
 320 #define nf_info_reroute(x) ((void *)x + sizeof(struct nf_info))
 321
 322 #include <net/flow.h>
 323 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 324
 325 static inline void
 326 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 327 {
 328 #ifdef CONFIG_IP_NF_NAT_NEEDED
 329         void (*decodefn)(struct sk_buff *, struct flowi *);
 330
 331         if (family == AF_INET && (decodefn = ip_nat_decode_session) != NULL)
 332                 decodefn(skb, fl);
 333 #endif
 334 }
 335
 336 #ifdef CONFIG_PROC_FS
 337 #include <linux/proc_fs.h>
 338 extern struct proc_dir_entry *proc_net_netfilter;
 339 #endif
 340
 341 #else /* !CONFIG_NETFILTER */
 342 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 343 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 344 static inline int nf_hook_thresh(int pf, unsigned int hook,
 345                                  struct sk_buff **pskb,
 346                                  struct net_device *indev,
 347                                  struct net_device *outdev,
 348                                  int (*okfn)(struct sk_buff *), int thresh,
 349                                  int cond)
 350 {
 351         return okfn(*pskb);
 352 }
 353 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff **pskb,
 354                           struct net_device *indev, struct net_device *outdev,
 355                           int (*okfn)(struct sk_buff *))
 356 {
 357         return 1;
 358 }
 359 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 360 struct flowi;
 361 static inline void
 362 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 363 #endif /*CONFIG_NETFILTER*/
 364
 365 #endif /*__KERNEL__*/
 366 #endif /*__LINUX_NETFILTER_H*/