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         struct list_head list;
  98
  99         /* User fills in from here down. */
 100         nf_hookfn *hook;
 101         struct module *owner;
 102         u_int8_t pf;
 103         unsigned int hooknum;
 104         /* Hooks are ordered in ascending priority. */
 105         int priority;
 106 };
 107
 108 struct nf_sockopt_ops {
 109         struct list_head list;
 110
 111         u_int8_t pf;
 112
 113         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 114         int set_optmin;
 115         int set_optmax;
 116         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 117         int (*compat_set)(struct sock *sk, int optval,
 118                         void __user *user, unsigned int len);
 119
 120         int get_optmin;
 121         int get_optmax;
 122         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 123         int (*compat_get)(struct sock *sk, int optval,
 124                         void __user *user, int *len);
 125
 126         /* Use the module struct to lock set/get code in place */
 127         struct module *owner;
 128 };
 129
 130 /* Function to register/unregister hook points. */
 131 int nf_register_hook(struct nf_hook_ops *reg);
 132 void nf_unregister_hook(struct nf_hook_ops *reg);
 133 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 134 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 135
 136 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 137    need to check permissions yourself! */
 138 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 139 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 140
 141 #ifdef CONFIG_SYSCTL
 142 /* Sysctl registration */
 143 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 144 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 145 #endif /* CONFIG_SYSCTL */
 146
 147 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 148
 149 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 150                  struct net_device *indev, struct net_device *outdev,
 151                  int (*okfn)(struct sk_buff *), int thresh);
 152
 153 /**
 154  *      nf_hook_thresh - call a netfilter hook
 155  *
 156  *      Returns 1 if the hook has allowed the packet to pass.  The function
 157  *      okfn must be invoked by the caller in this case.  Any other return
 158  *      value indicates the packet has been consumed by the hook.
 159  */
 160 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 161                                  struct sk_buff *skb,
 162                                  struct net_device *indev,
 163                                  struct net_device *outdev,
 164                                  int (*okfn)(struct sk_buff *), int thresh,
 165                                  int cond)
 166 {
 167         if (!cond)
 168                 return 1;
 169 #ifndef CONFIG_NETFILTER_DEBUG
 170         if (list_empty(&nf_hooks[pf][hook]))
 171                 return 1;
 172 #endif
 173         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 174 }
 175
 176 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 177                           struct net_device *indev, struct net_device *outdev,
 178                           int (*okfn)(struct sk_buff *))
 179 {
 180         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 181 }
 182
 183 /* Activate hook; either okfn or kfree_skb called, unless a hook
 184    returns NF_STOLEN (in which case, it's up to the hook to deal with
 185    the consequences).
 186
 187    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 188    accepted.
 189 */
 190
 191 /* RR:
 192    > I don't want nf_hook to return anything because people might forget
 193    > about async and trust the return value to mean "packet was ok".
 194
 195    AK:
 196    Just document it clearly, then you can expect some sense from kernel
 197    coders :)
 198 */
 199
 200 /* This is gross, but inline doesn't cut it for avoiding the function
 201    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 202
 203 /* HX: It's slightly less gross now. */
 204
 205 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 206 ({int __ret;                                                                   \
 207 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 208         __ret = (okfn)(skb);                                                   \
 209 __ret;})
 210
 211 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 212 ({int __ret;                                                                   \
 213 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 214         __ret = (okfn)(skb);                                                   \
 215 __ret;})
 216
 217 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 218         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 219
 220 /* Call setsockopt() */
 221 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 222                   unsigned int len);
 223 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 224                   int *len);
 225
 226 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 227                 char __user *opt, unsigned int len);
 228 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 229                 char __user *opt, int *len);
 230
 231 /* Call this before modifying an existing packet: ensures it is
 232    modifiable and linear to the point you care about (writable_len).
 233    Returns true or false. */
 234 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 235
 236 struct flowi;
 237 struct nf_queue_entry;
 238
 239 struct nf_afinfo {
 240         unsigned short  family;
 241         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 242                                     unsigned int dataoff, u_int8_t protocol);
 243         __sum16         (*checksum_partial)(struct sk_buff *skb,
 244                                             unsigned int hook,
 245                                             unsigned int dataoff,
 246                                             unsigned int len,
 247                                             u_int8_t protocol);
 248         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 249         void            (*saveroute)(const struct sk_buff *skb,
 250                                      struct nf_queue_entry *entry);
 251         int             (*reroute)(struct sk_buff *skb,
 252                                    const struct nf_queue_entry *entry);
 253         int             route_key_size;
 254 };
 255
 256 extern const struct nf_afinfo *nf_afinfo[NFPROTO_NUMPROTO];
 257 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 258 {
 259         return rcu_dereference(nf_afinfo[family]);
 260 }
 261
 262 static inline __sum16
 263 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 264             u_int8_t protocol, unsigned short family)
 265 {
 266         const struct nf_afinfo *afinfo;
 267         __sum16 csum = 0;
 268
 269         rcu_read_lock();
 270         afinfo = nf_get_afinfo(family);
 271         if (afinfo)
 272                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 273         rcu_read_unlock();
 274         return csum;
 275 }
 276
 277 static inline __sum16
 278 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 279                     unsigned int dataoff, unsigned int len,
 280                     u_int8_t protocol, unsigned short family)
 281 {
 282         const struct nf_afinfo *afinfo;
 283         __sum16 csum = 0;
 284
 285         rcu_read_lock();
 286         afinfo = nf_get_afinfo(family);
 287         if (afinfo)
 288                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 289                                                 protocol);
 290         rcu_read_unlock();
 291         return csum;
 292 }
 293
 294 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 295 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 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, u_int8_t family)
 302 {
 303 #ifdef CONFIG_NF_NAT_NEEDED
 304         void (*decodefn)(struct sk_buff *, struct flowi *);
 305
 306         if (family == AF_INET) {
 307                 rcu_read_lock();
 308                 decodefn = rcu_dereference(ip_nat_decode_session);
 309                 if (decodefn)
 310                         decodefn(skb, fl);
 311                 rcu_read_unlock();
 312         }
 313 #endif
 314 }
 315
 316 #ifdef CONFIG_PROC_FS
 317 #include <linux/proc_fs.h>
 318 extern struct proc_dir_entry *proc_net_netfilter;
 319 #endif
 320
 321 #else /* !CONFIG_NETFILTER */
 322 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 323 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 324 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 325                                  struct sk_buff *skb,
 326                                  struct net_device *indev,
 327                                  struct net_device *outdev,
 328                                  int (*okfn)(struct sk_buff *), int thresh,
 329                                  int cond)
 330 {
 331         return okfn(skb);
 332 }
 333 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 334                           struct net_device *indev, struct net_device *outdev,
 335                           int (*okfn)(struct sk_buff *))
 336 {
 337         return 1;
 338 }
 339 struct flowi;
 340 static inline void
 341 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 342 {
 343 }
 344 #endif /*CONFIG_NETFILTER*/
 345
 346 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 347 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 348 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 349 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 350 #else
 351 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 352 #endif
 353
 354 #endif /*__KERNEL__*/
 355 #endif /*__LINUX_NETFILTER_H*/