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/skbuff.h>
   7 #include <linux/net.h>
   8 #include <linux/if.h>
   9 #include <linux/in.h>
  10 #include <linux/in6.h>
  11 #include <linux/wait.h>
  12 #include <linux/list.h>
  13 #endif
  14 #include <linux/types.h>
  15 #include <linux/compiler.h>
  16
  17 /* Responses from hook functions. */
  18 #define NF_DROP 0
  19 #define NF_ACCEPT 1
  20 #define NF_STOLEN 2
  21 #define NF_QUEUE 3
  22 #define NF_REPEAT 4
  23 #define NF_STOP 5
  24 #define NF_MAX_VERDICT NF_STOP
  25
  26 /* we overload the higher bits for encoding auxiliary data such as the queue
  27  * number. Not nice, but better than additional function arguments. */
  28 #define NF_VERDICT_MASK 0x0000ffff
  29 #define NF_VERDICT_BITS 16
  30
  31 #define NF_VERDICT_QMASK 0xffff0000
  32 #define NF_VERDICT_QBITS 16
  33
  34 #define NF_QUEUE_NR(x) ((((x) << NF_VERDICT_BITS) & NF_VERDICT_QMASK) | NF_QUEUE)
  35
  36 /* only for userspace compatibility */
  37 #ifndef __KERNEL__
  38 /* Generic cache responses from hook functions.
  39    <= 0x2000 is used for protocol-flags. */
  40 #define NFC_UNKNOWN 0x4000
  41 #define NFC_ALTERED 0x8000
  42 #endif
  43
  44 enum nf_inet_hooks {
  45         NF_INET_PRE_ROUTING,
  46         NF_INET_LOCAL_IN,
  47         NF_INET_FORWARD,
  48         NF_INET_LOCAL_OUT,
  49         NF_INET_POST_ROUTING,
  50         NF_INET_NUMHOOKS
  51 };
  52
  53 enum {
  54         NFPROTO_UNSPEC =  0,
  55         NFPROTO_IPV4   =  2,
  56         NFPROTO_ARP    =  3,
  57         NFPROTO_BRIDGE =  7,
  58         NFPROTO_IPV6   = 10,
  59         NFPROTO_DECNET = 12,
  60         NFPROTO_NUMPROTO,
  61 };
  62
  63 union nf_inet_addr {
  64         __u32           all[4];
  65         __be32          ip;
  66         __be32          ip6[4];
  67         struct in_addr  in;
  68         struct in6_addr in6;
  69 };
  70
  71 #ifdef __KERNEL__
  72 #ifdef CONFIG_NETFILTER
  73
  74 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  75                                    const union nf_inet_addr *a2)
  76 {
  77         return a1->all[0] == a2->all[0] &&
  78                a1->all[1] == a2->all[1] &&
  79                a1->all[2] == a2->all[2] &&
  80                a1->all[3] == a2->all[3];
  81 }
  82
  83 extern void netfilter_init(void);
  84
  85 /* Largest hook number + 1 */
  86 #define NF_MAX_HOOKS 8
  87
  88 struct sk_buff;
  89
  90 typedef unsigned int nf_hookfn(unsigned int hooknum,
  91                                struct sk_buff *skb,
  92                                const struct net_device *in,
  93                                const struct net_device *out,
  94                                int (*okfn)(struct sk_buff *));
  95
  96 struct nf_hook_ops
  97 {
  98         struct list_head list;
  99
 100         /* User fills in from here down. */
 101         nf_hookfn *hook;
 102         struct module *owner;
 103         u_int8_t pf;
 104         unsigned int hooknum;
 105         /* Hooks are ordered in ascending priority. */
 106         int priority;
 107 };
 108
 109 struct nf_sockopt_ops
 110 {
 111         struct list_head list;
 112
 113         u_int8_t pf;
 114
 115         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 116         int set_optmin;
 117         int set_optmax;
 118         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 119         int (*compat_set)(struct sock *sk, int optval,
 120                         void __user *user, unsigned int len);
 121
 122         int get_optmin;
 123         int get_optmax;
 124         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 125         int (*compat_get)(struct sock *sk, int optval,
 126                         void __user *user, int *len);
 127
 128         /* Use the module struct to lock set/get code in place */
 129         struct module *owner;
 130 };
 131
 132 /* Function to register/unregister hook points. */
 133 int nf_register_hook(struct nf_hook_ops *reg);
 134 void nf_unregister_hook(struct nf_hook_ops *reg);
 135 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 136 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 137
 138 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 139    need to check permissions yourself! */
 140 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 141 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 142
 143 #ifdef CONFIG_SYSCTL
 144 /* Sysctl registration */
 145 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 146 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 147 #endif /* CONFIG_SYSCTL */
 148
 149 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 150
 151 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 152                  struct net_device *indev, struct net_device *outdev,
 153                  int (*okfn)(struct sk_buff *), int thresh);
 154
 155 /**
 156  *      nf_hook_thresh - call a netfilter hook
 157  *
 158  *      Returns 1 if the hook has allowed the packet to pass.  The function
 159  *      okfn must be invoked by the caller in this case.  Any other return
 160  *      value indicates the packet has been consumed by the hook.
 161  */
 162 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 163                                  struct sk_buff *skb,
 164                                  struct net_device *indev,
 165                                  struct net_device *outdev,
 166                                  int (*okfn)(struct sk_buff *), int thresh,
 167                                  int cond)
 168 {
 169         if (!cond)
 170                 return 1;
 171 #ifndef CONFIG_NETFILTER_DEBUG
 172         if (list_empty(&nf_hooks[pf][hook]))
 173                 return 1;
 174 #endif
 175         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 176 }
 177
 178 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 179                           struct net_device *indev, struct net_device *outdev,
 180                           int (*okfn)(struct sk_buff *))
 181 {
 182         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 183 }
 184
 185 /* Activate hook; either okfn or kfree_skb called, unless a hook
 186    returns NF_STOLEN (in which case, it's up to the hook to deal with
 187    the consequences).
 188
 189    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 190    accepted.
 191 */
 192
 193 /* RR:
 194    > I don't want nf_hook to return anything because people might forget
 195    > about async and trust the return value to mean "packet was ok".
 196
 197    AK:
 198    Just document it clearly, then you can expect some sense from kernel
 199    coders :)
 200 */
 201
 202 /* This is gross, but inline doesn't cut it for avoiding the function
 203    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 204
 205 /* HX: It's slightly less gross now. */
 206
 207 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 208 ({int __ret;                                                                   \
 209 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 210         __ret = (okfn)(skb);                                                   \
 211 __ret;})
 212
 213 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 214 ({int __ret;                                                                   \
 215 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 216         __ret = (okfn)(skb);                                                   \
 217 __ret;})
 218
 219 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 220         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 221
 222 /* Call setsockopt() */
 223 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 224                   int len);
 225 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 226                   int *len);
 227
 228 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 229                 char __user *opt, int len);
 230 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 231                 char __user *opt, int *len);
 232
 233 /* Call this before modifying an existing packet: ensures it is
 234    modifiable and linear to the point you care about (writable_len).
 235    Returns true or false. */
 236 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 237
 238 struct flowi;
 239 struct nf_queue_entry;
 240
 241 struct nf_afinfo {
 242         unsigned short  family;
 243         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 244                                     unsigned int dataoff, u_int8_t protocol);
 245         __sum16         (*checksum_partial)(struct sk_buff *skb,
 246                                             unsigned int hook,
 247                                             unsigned int dataoff,
 248                                             unsigned int len,
 249                                             u_int8_t protocol);
 250         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 251         void            (*saveroute)(const struct sk_buff *skb,
 252                                      struct nf_queue_entry *entry);
 253         int             (*reroute)(struct sk_buff *skb,
 254                                    const struct nf_queue_entry *entry);
 255         int             route_key_size;
 256 };
 257
 258 extern const struct nf_afinfo *nf_afinfo[NFPROTO_NUMPROTO];
 259 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 260 {
 261         return rcu_dereference(nf_afinfo[family]);
 262 }
 263
 264 static inline __sum16
 265 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 266             u_int8_t protocol, unsigned short family)
 267 {
 268         const struct nf_afinfo *afinfo;
 269         __sum16 csum = 0;
 270
 271         rcu_read_lock();
 272         afinfo = nf_get_afinfo(family);
 273         if (afinfo)
 274                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 275         rcu_read_unlock();
 276         return csum;
 277 }
 278
 279 static inline __sum16
 280 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 281                     unsigned int dataoff, unsigned int len,
 282                     u_int8_t protocol, unsigned short family)
 283 {
 284         const struct nf_afinfo *afinfo;
 285         __sum16 csum = 0;
 286
 287         rcu_read_lock();
 288         afinfo = nf_get_afinfo(family);
 289         if (afinfo)
 290                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 291                                                 protocol);
 292         rcu_read_unlock();
 293         return csum;
 294 }
 295
 296 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 297 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 298
 299 #include <net/flow.h>
 300 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 301
 302 static inline void
 303 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 304 {
 305 #ifdef CONFIG_NF_NAT_NEEDED
 306         void (*decodefn)(struct sk_buff *, struct flowi *);
 307
 308         if (family == AF_INET) {
 309                 rcu_read_lock();
 310                 decodefn = rcu_dereference(ip_nat_decode_session);
 311                 if (decodefn)
 312                         decodefn(skb, fl);
 313                 rcu_read_unlock();
 314         }
 315 #endif
 316 }
 317
 318 #ifdef CONFIG_PROC_FS
 319 #include <linux/proc_fs.h>
 320 extern struct proc_dir_entry *proc_net_netfilter;
 321 #endif
 322
 323 #else /* !CONFIG_NETFILTER */
 324 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 325 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 326 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 327                                  struct sk_buff *skb,
 328                                  struct net_device *indev,
 329                                  struct net_device *outdev,
 330                                  int (*okfn)(struct sk_buff *), int thresh,
 331                                  int cond)
 332 {
 333         return okfn(skb);
 334 }
 335 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 336                           struct net_device *indev, struct net_device *outdev,
 337                           int (*okfn)(struct sk_buff *))
 338 {
 339         return 1;
 340 }
 341 struct flowi;
 342 static inline void
 343 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 344 {
 345 }
 346 #endif /*CONFIG_NETFILTER*/
 347
 348 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 349 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 350 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 351 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 352 #else
 353 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 354 #endif
 355
 356 #endif /*__KERNEL__*/
 357 #endif /*__LINUX_NETFILTER_H*/