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 or errno values. Not nice, but better than additional function
  28  * arguments. */
  29 #define NF_VERDICT_MASK 0x000000ff
  30
  31 /* extra verdict flags have mask 0x0000ff00 */
  32
  33 /* queue number (NF_QUEUE) or errno (NF_DROP) */
  34 #define NF_VERDICT_QMASK 0xffff0000
  35 #define NF_VERDICT_QBITS 16
  36
  37 #define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE)
  38
  39 #define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP)
  40
  41 /* only for userspace compatibility */
  42 #ifndef __KERNEL__
  43 /* Generic cache responses from hook functions.
  44    <= 0x2000 is used for protocol-flags. */
  45 #define NFC_UNKNOWN 0x4000
  46 #define NFC_ALTERED 0x8000
  47
  48 /* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */
  49 #define NF_VERDICT_BITS 16
  50 #endif
  51
  52 enum nf_inet_hooks {
  53         NF_INET_PRE_ROUTING,
  54         NF_INET_LOCAL_IN,
  55         NF_INET_FORWARD,
  56         NF_INET_LOCAL_OUT,
  57         NF_INET_POST_ROUTING,
  58         NF_INET_NUMHOOKS
  59 };
  60
  61 enum {
  62         NFPROTO_UNSPEC =  0,
  63         NFPROTO_IPV4   =  2,
  64         NFPROTO_ARP    =  3,
  65         NFPROTO_BRIDGE =  7,
  66         NFPROTO_IPV6   = 10,
  67         NFPROTO_DECNET = 12,
  68         NFPROTO_NUMPROTO,
  69 };
  70
  71 union nf_inet_addr {
  72         __u32           all[4];
  73         __be32          ip;
  74         __be32          ip6[4];
  75         struct in_addr  in;
  76         struct in6_addr in6;
  77 };
  78
  79 #ifdef __KERNEL__
  80 #ifdef CONFIG_NETFILTER
  81 static inline int NF_DROP_GETERR(int verdict)
  82 {
  83         return -(verdict >> NF_VERDICT_QBITS);
  84 }
  85
  86 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  87                                    const union nf_inet_addr *a2)
  88 {
  89         return a1->all[0] == a2->all[0] &&
  90                a1->all[1] == a2->all[1] &&
  91                a1->all[2] == a2->all[2] &&
  92                a1->all[3] == a2->all[3];
  93 }
  94
  95 extern void netfilter_init(void);
  96
  97 /* Largest hook number + 1 */
  98 #define NF_MAX_HOOKS 8
  99
 100 struct sk_buff;
 101
 102 typedef unsigned int nf_hookfn(unsigned int hooknum,
 103                                struct sk_buff *skb,
 104                                const struct net_device *in,
 105                                const struct net_device *out,
 106                                int (*okfn)(struct sk_buff *));
 107
 108 struct nf_hook_ops {
 109         struct list_head list;
 110
 111         /* User fills in from here down. */
 112         nf_hookfn *hook;
 113         struct module *owner;
 114         u_int8_t pf;
 115         unsigned int hooknum;
 116         /* Hooks are ordered in ascending priority. */
 117         int priority;
 118 };
 119
 120 struct nf_sockopt_ops {
 121         struct list_head list;
 122
 123         u_int8_t pf;
 124
 125         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 126         int set_optmin;
 127         int set_optmax;
 128         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 129 #ifdef CONFIG_COMPAT
 130         int (*compat_set)(struct sock *sk, int optval,
 131                         void __user *user, unsigned int len);
 132 #endif
 133         int get_optmin;
 134         int get_optmax;
 135         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 136 #ifdef CONFIG_COMPAT
 137         int (*compat_get)(struct sock *sk, int optval,
 138                         void __user *user, int *len);
 139 #endif
 140         /* Use the module struct to lock set/get code in place */
 141         struct module *owner;
 142 };
 143
 144 /* Function to register/unregister hook points. */
 145 int nf_register_hook(struct nf_hook_ops *reg);
 146 void nf_unregister_hook(struct nf_hook_ops *reg);
 147 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 148 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 149
 150 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 151    need to check permissions yourself! */
 152 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 153 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 154
 155 #ifdef CONFIG_SYSCTL
 156 /* Sysctl registration */
 157 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 158 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 159 #endif /* CONFIG_SYSCTL */
 160
 161 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 162
 163 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 164                  struct net_device *indev, struct net_device *outdev,
 165                  int (*okfn)(struct sk_buff *), int thresh);
 166
 167 /**
 168  *      nf_hook_thresh - call a netfilter hook
 169  *
 170  *      Returns 1 if the hook has allowed the packet to pass.  The function
 171  *      okfn must be invoked by the caller in this case.  Any other return
 172  *      value indicates the packet has been consumed by the hook.
 173  */
 174 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 175                                  struct sk_buff *skb,
 176                                  struct net_device *indev,
 177                                  struct net_device *outdev,
 178                                  int (*okfn)(struct sk_buff *), int thresh)
 179 {
 180 #ifndef CONFIG_NETFILTER_DEBUG
 181         if (list_empty(&nf_hooks[pf][hook]))
 182                 return 1;
 183 #endif
 184         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 185 }
 186
 187 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 188                           struct net_device *indev, struct net_device *outdev,
 189                           int (*okfn)(struct sk_buff *))
 190 {
 191         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 192 }
 193
 194 /* Activate hook; either okfn or kfree_skb called, unless a hook
 195    returns NF_STOLEN (in which case, it's up to the hook to deal with
 196    the consequences).
 197
 198    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 199    accepted.
 200 */
 201
 202 /* RR:
 203    > I don't want nf_hook to return anything because people might forget
 204    > about async and trust the return value to mean "packet was ok".
 205
 206    AK:
 207    Just document it clearly, then you can expect some sense from kernel
 208    coders :)
 209 */
 210
 211 static inline int
 212 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 213                struct net_device *in, struct net_device *out,
 214                int (*okfn)(struct sk_buff *), int thresh)
 215 {
 216         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 217         if (ret == 1)
 218                 ret = okfn(skb);
 219         return ret;
 220 }
 221
 222 static inline int
 223 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 224              struct net_device *in, struct net_device *out,
 225              int (*okfn)(struct sk_buff *), bool cond)
 226 {
 227         int ret;
 228
 229         if (!cond ||
 230             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 231                 ret = okfn(skb);
 232         return ret;
 233 }
 234
 235 static inline int
 236 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 237         struct net_device *in, struct net_device *out,
 238         int (*okfn)(struct sk_buff *))
 239 {
 240         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 241 }
 242
 243 /* Call setsockopt() */
 244 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 245                   unsigned int len);
 246 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 247                   int *len);
 248 #ifdef CONFIG_COMPAT
 249 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 250                 char __user *opt, unsigned int len);
 251 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 252                 char __user *opt, int *len);
 253 #endif
 254
 255 /* Call this before modifying an existing packet: ensures it is
 256    modifiable and linear to the point you care about (writable_len).
 257    Returns true or false. */
 258 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 259
 260 struct flowi;
 261 struct nf_queue_entry;
 262
 263 struct nf_afinfo {
 264         unsigned short  family;
 265         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 266                                     unsigned int dataoff, u_int8_t protocol);
 267         __sum16         (*checksum_partial)(struct sk_buff *skb,
 268                                             unsigned int hook,
 269                                             unsigned int dataoff,
 270                                             unsigned int len,
 271                                             u_int8_t protocol);
 272         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 273         void            (*saveroute)(const struct sk_buff *skb,
 274                                      struct nf_queue_entry *entry);
 275         int             (*reroute)(struct sk_buff *skb,
 276                                    const struct nf_queue_entry *entry);
 277         int             route_key_size;
 278 };
 279
 280 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 281 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 282 {
 283         return rcu_dereference(nf_afinfo[family]);
 284 }
 285
 286 static inline __sum16
 287 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 288             u_int8_t protocol, unsigned short family)
 289 {
 290         const struct nf_afinfo *afinfo;
 291         __sum16 csum = 0;
 292
 293         rcu_read_lock();
 294         afinfo = nf_get_afinfo(family);
 295         if (afinfo)
 296                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 297         rcu_read_unlock();
 298         return csum;
 299 }
 300
 301 static inline __sum16
 302 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 303                     unsigned int dataoff, unsigned int len,
 304                     u_int8_t protocol, unsigned short family)
 305 {
 306         const struct nf_afinfo *afinfo;
 307         __sum16 csum = 0;
 308
 309         rcu_read_lock();
 310         afinfo = nf_get_afinfo(family);
 311         if (afinfo)
 312                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 313                                                 protocol);
 314         rcu_read_unlock();
 315         return csum;
 316 }
 317
 318 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 319 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 320
 321 #include <net/flow.h>
 322 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 323
 324 static inline void
 325 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 326 {
 327 #ifdef CONFIG_NF_NAT_NEEDED
 328         void (*decodefn)(struct sk_buff *, struct flowi *);
 329
 330         if (family == AF_INET) {
 331                 rcu_read_lock();
 332                 decodefn = rcu_dereference(ip_nat_decode_session);
 333                 if (decodefn)
 334                         decodefn(skb, fl);
 335                 rcu_read_unlock();
 336         }
 337 #endif
 338 }
 339
 340 #ifdef CONFIG_PROC_FS
 341 #include <linux/proc_fs.h>
 342 extern struct proc_dir_entry *proc_net_netfilter;
 343 #endif
 344
 345 #else /* !CONFIG_NETFILTER */
 346 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 347 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 348 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 349                                  struct sk_buff *skb,
 350                                  struct net_device *indev,
 351                                  struct net_device *outdev,
 352                                  int (*okfn)(struct sk_buff *), int thresh)
 353 {
 354         return okfn(skb);
 355 }
 356 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 357                           struct net_device *indev, struct net_device *outdev,
 358                           int (*okfn)(struct sk_buff *))
 359 {
 360         return 1;
 361 }
 362 struct flowi;
 363 static inline void
 364 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 365 {
 366 }
 367 #endif /*CONFIG_NETFILTER*/
 368
 369 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 370 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 371 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 372 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 373 #else
 374 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 375 #endif
 376
 377 #endif /*__KERNEL__*/
 378 #endif /*__LINUX_NETFILTER_H*/