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/netdevice.h>
   9 #include <linux/if.h>
  10 #include <linux/in.h>
  11 #include <linux/in6.h>
  12 #include <linux/wait.h>
  13 #include <linux/list.h>
  14 #include <net/net_namespace.h>
  15 #endif
  16 #include <linux/types.h>
  17 #include <linux/compiler.h>
  18
  19 /* Responses from hook functions. */
  20 #define NF_DROP 0
  21 #define NF_ACCEPT 1
  22 #define NF_STOLEN 2
  23 #define NF_QUEUE 3
  24 #define NF_REPEAT 4
  25 #define NF_STOP 5
  26 #define NF_MAX_VERDICT NF_STOP
  27
  28 /* we overload the higher bits for encoding auxiliary data such as the queue
  29  * number. Not nice, but better than additional function arguments. */
  30 #define NF_VERDICT_MASK 0x0000ffff
  31 #define NF_VERDICT_BITS 16
  32
  33 #define NF_VERDICT_QMASK 0xffff0000
  34 #define NF_VERDICT_QBITS 16
  35
  36 #define NF_QUEUE_NR(x) ((((x) << NF_VERDICT_BITS) & NF_VERDICT_QMASK) | NF_QUEUE)
  37
  38 /* only for userspace compatibility */
  39 #ifndef __KERNEL__
  40 /* Generic cache responses from hook functions.
  41    <= 0x2000 is used for protocol-flags. */
  42 #define NFC_UNKNOWN 0x4000
  43 #define NFC_ALTERED 0x8000
  44 #endif
  45
  46 enum nf_inet_hooks {
  47         NF_INET_PRE_ROUTING,
  48         NF_INET_LOCAL_IN,
  49         NF_INET_FORWARD,
  50         NF_INET_LOCAL_OUT,
  51         NF_INET_POST_ROUTING,
  52         NF_INET_NUMHOOKS
  53 };
  54
  55 union nf_inet_addr {
  56         __u32           all[4];
  57         __be32          ip;
  58         __be32          ip6[4];
  59         struct in_addr  in;
  60         struct in6_addr in6;
  61 };
  62
  63 #ifdef __KERNEL__
  64 #ifdef CONFIG_NETFILTER
  65
  66 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  67                                    const union nf_inet_addr *a2)
  68 {
  69         return a1->all[0] == a2->all[0] &&
  70                a1->all[1] == a2->all[1] &&
  71                a1->all[2] == a2->all[2] &&
  72                a1->all[3] == a2->all[3];
  73 }
  74
  75 extern void netfilter_init(void);
  76
  77 /* Largest hook number + 1 */
  78 #define NF_MAX_HOOKS 8
  79
  80 struct sk_buff;
  81
  82 typedef unsigned int nf_hookfn(unsigned int hooknum,
  83                                struct sk_buff *skb,
  84                                const struct net_device *in,
  85                                const struct net_device *out,
  86                                int (*okfn)(struct sk_buff *));
  87
  88 struct nf_hook_ops
  89 {
  90         struct list_head list;
  91
  92         /* User fills in from here down. */
  93         nf_hookfn *hook;
  94         struct module *owner;
  95         int pf;
  96         int hooknum;
  97         /* Hooks are ordered in ascending priority. */
  98         int priority;
  99 };
 100
 101 struct nf_sockopt_ops
 102 {
 103         struct list_head list;
 104
 105         int pf;
 106
 107         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 108         int set_optmin;
 109         int set_optmax;
 110         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 111         int (*compat_set)(struct sock *sk, int optval,
 112                         void __user *user, unsigned int len);
 113
 114         int get_optmin;
 115         int get_optmax;
 116         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 117         int (*compat_get)(struct sock *sk, int optval,
 118                         void __user *user, int *len);
 119
 120         /* Use the module struct to lock set/get code in place */
 121         struct module *owner;
 122 };
 123
 124 /* Function to register/unregister hook points. */
 125 int nf_register_hook(struct nf_hook_ops *reg);
 126 void nf_unregister_hook(struct nf_hook_ops *reg);
 127 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 128 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 129
 130 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 131    need to check permissions yourself! */
 132 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 133 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 134
 135 #ifdef CONFIG_SYSCTL
 136 /* Sysctl registration */
 137 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 138 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 139 #endif /* CONFIG_SYSCTL */
 140
 141 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 142
 143 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 144                  struct net_device *indev, struct net_device *outdev,
 145                  int (*okfn)(struct sk_buff *), int thresh);
 146
 147 /**
 148  *      nf_hook_thresh - call a netfilter hook
 149  *
 150  *      Returns 1 if the hook has allowed the packet to pass.  The function
 151  *      okfn must be invoked by the caller in this case.  Any other return
 152  *      value indicates the packet has been consumed by the hook.
 153  */
 154 static inline int nf_hook_thresh(int pf, unsigned int hook,
 155                                  struct sk_buff *skb,
 156                                  struct net_device *indev,
 157                                  struct net_device *outdev,
 158                                  int (*okfn)(struct sk_buff *), int thresh,
 159                                  int cond)
 160 {
 161         if (!cond)
 162                 return 1;
 163 #ifndef CONFIG_NETFILTER_DEBUG
 164         if (list_empty(&nf_hooks[pf][hook]))
 165                 return 1;
 166 #endif
 167         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 168 }
 169
 170 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 171                           struct net_device *indev, struct net_device *outdev,
 172                           int (*okfn)(struct sk_buff *))
 173 {
 174         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 175 }
 176
 177 /* Activate hook; either okfn or kfree_skb called, unless a hook
 178    returns NF_STOLEN (in which case, it's up to the hook to deal with
 179    the consequences).
 180
 181    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 182    accepted.
 183 */
 184
 185 /* RR:
 186    > I don't want nf_hook to return anything because people might forget
 187    > about async and trust the return value to mean "packet was ok".
 188
 189    AK:
 190    Just document it clearly, then you can expect some sense from kernel
 191    coders :)
 192 */
 193
 194 /* This is gross, but inline doesn't cut it for avoiding the function
 195    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 196
 197 /* HX: It's slightly less gross now. */
 198
 199 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 200 ({int __ret;                                                                   \
 201 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 202         __ret = (okfn)(skb);                                                   \
 203 __ret;})
 204
 205 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 206 ({int __ret;                                                                   \
 207 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 208         __ret = (okfn)(skb);                                                   \
 209 __ret;})
 210
 211 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 212         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 213
 214 /* Call setsockopt() */
 215 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 216                   int len);
 217 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 218                   int *len);
 219
 220 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 221                 char __user *opt, int len);
 222 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 223                 char __user *opt, int *len);
 224
 225 /* Call this before modifying an existing packet: ensures it is
 226    modifiable and linear to the point you care about (writable_len).
 227    Returns true or false. */
 228 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 229
 230 struct flowi;
 231 struct nf_queue_entry;
 232
 233 struct nf_afinfo {
 234         unsigned short  family;
 235         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 236                                     unsigned int dataoff, u_int8_t protocol);
 237         __sum16         (*checksum_partial)(struct sk_buff *skb,
 238                                             unsigned int hook,
 239                                             unsigned int dataoff,
 240                                             unsigned int len,
 241                                             u_int8_t protocol);
 242         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 243         void            (*saveroute)(const struct sk_buff *skb,
 244                                      struct nf_queue_entry *entry);
 245         int             (*reroute)(struct sk_buff *skb,
 246                                    const struct nf_queue_entry *entry);
 247         int             route_key_size;
 248 };
 249
 250 extern const struct nf_afinfo *nf_afinfo[NPROTO];
 251 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 252 {
 253         return rcu_dereference(nf_afinfo[family]);
 254 }
 255
 256 static inline __sum16
 257 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 258             u_int8_t protocol, unsigned short family)
 259 {
 260         const struct nf_afinfo *afinfo;
 261         __sum16 csum = 0;
 262
 263         rcu_read_lock();
 264         afinfo = nf_get_afinfo(family);
 265         if (afinfo)
 266                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 267         rcu_read_unlock();
 268         return csum;
 269 }
 270
 271 static inline __sum16
 272 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 273                     unsigned int dataoff, unsigned int len,
 274                     u_int8_t protocol, unsigned short family)
 275 {
 276         const struct nf_afinfo *afinfo;
 277         __sum16 csum = 0;
 278
 279         rcu_read_lock();
 280         afinfo = nf_get_afinfo(family);
 281         if (afinfo)
 282                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 283                                                 protocol);
 284         rcu_read_unlock();
 285         return csum;
 286 }
 287
 288 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 289 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 290
 291 #include <net/flow.h>
 292 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 293
 294 static inline void
 295 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 296 {
 297 #ifdef CONFIG_NF_NAT_NEEDED
 298         void (*decodefn)(struct sk_buff *, struct flowi *);
 299
 300         if (family == AF_INET) {
 301                 rcu_read_lock();
 302                 decodefn = rcu_dereference(ip_nat_decode_session);
 303                 if (decodefn)
 304                         decodefn(skb, fl);
 305                 rcu_read_unlock();
 306         }
 307 #endif
 308 }
 309
 310 #ifdef CONFIG_PROC_FS
 311 #include <linux/proc_fs.h>
 312 extern struct proc_dir_entry *proc_net_netfilter;
 313 #endif
 314
 315 #else /* !CONFIG_NETFILTER */
 316 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 317 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 318 static inline int nf_hook_thresh(int pf, unsigned int hook,
 319                                  struct sk_buff *skb,
 320                                  struct net_device *indev,
 321                                  struct net_device *outdev,
 322                                  int (*okfn)(struct sk_buff *), int thresh,
 323                                  int cond)
 324 {
 325         return okfn(skb);
 326 }
 327 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 328                           struct net_device *indev, struct net_device *outdev,
 329                           int (*okfn)(struct sk_buff *))
 330 {
 331         return 1;
 332 }
 333 struct flowi;
 334 static inline void
 335 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 336 #endif /*CONFIG_NETFILTER*/
 337
 338 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 339 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 340 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 341 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 342 #else
 343 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 344 #endif
 345
 346 static inline struct net *nf_pre_routing_net(const struct net_device *in,
 347                                              const struct net_device *out)
 348 {
 349 #ifdef CONFIG_NET_NS
 350         return in->nd_net;
 351 #else
 352         return &init_net;
 353 #endif
 354 }
 355
 356 static inline struct net *nf_local_in_net(const struct net_device *in,
 357                                           const struct net_device *out)
 358 {
 359 #ifdef CONFIG_NET_NS
 360         return in->nd_net;
 361 #else
 362         return &init_net;
 363 #endif
 364 }
 365
 366 static inline struct net *nf_forward_net(const struct net_device *in,
 367                                          const struct net_device *out)
 368 {
 369 #ifdef CONFIG_NET_NS
 370         BUG_ON(in->nd_net != out->nd_net);
 371         return in->nd_net;
 372 #else
 373         return &init_net;
 374 #endif
 375 }
 376
 377 static inline struct net *nf_local_out_net(const struct net_device *in,
 378                                            const struct net_device *out)
 379 {
 380 #ifdef CONFIG_NET_NS
 381         return out->nd_net;
 382 #else
 383         return &init_net;
 384 #endif
 385 }
 386
 387 static inline struct net *nf_post_routing_net(const struct net_device *in,
 388                                               const struct net_device *out)
 389 {
 390 #ifdef CONFIG_NET_NS
 391         return out->nd_net;
 392 #else
 393         return &init_net;
 394 #endif
 395 }
 396
 397 #endif /*__KERNEL__*/
 398 #endif /*__LINUX_NETFILTER_H*/