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