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 #include <linux/sysctl.h>
  17
  18 /* Responses from hook functions. */
  19 #define NF_DROP 0
  20 #define NF_ACCEPT 1
  21 #define NF_STOLEN 2
  22 #define NF_QUEUE 3
  23 #define NF_REPEAT 4
  24 #define NF_STOP 5
  25 #define NF_MAX_VERDICT NF_STOP
  26
  27 /* we overload the higher bits for encoding auxiliary data such as the queue
  28  * number or errno values. Not nice, but better than additional function
  29  * arguments. */
  30 #define NF_VERDICT_MASK 0x000000ff
  31
  32 /* extra verdict flags have mask 0x0000ff00 */
  33 #define NF_VERDICT_FLAG_QUEUE_BYPASS    0x00008000
  34
  35 /* queue number (NF_QUEUE) or errno (NF_DROP) */
  36 #define NF_VERDICT_QMASK 0xffff0000
  37 #define NF_VERDICT_QBITS 16
  38
  39 #define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE)
  40
  41 #define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP)
  42
  43 /* only for userspace compatibility */
  44 #ifndef __KERNEL__
  45 /* Generic cache responses from hook functions.
  46    <= 0x2000 is used for protocol-flags. */
  47 #define NFC_UNKNOWN 0x4000
  48 #define NFC_ALTERED 0x8000
  49
  50 /* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */
  51 #define NF_VERDICT_BITS 16
  52 #endif
  53
  54 enum nf_inet_hooks {
  55         NF_INET_PRE_ROUTING,
  56         NF_INET_LOCAL_IN,
  57         NF_INET_FORWARD,
  58         NF_INET_LOCAL_OUT,
  59         NF_INET_POST_ROUTING,
  60         NF_INET_NUMHOOKS
  61 };
  62
  63 enum {
  64         NFPROTO_UNSPEC =  0,
  65         NFPROTO_IPV4   =  2,
  66         NFPROTO_ARP    =  3,
  67         NFPROTO_BRIDGE =  7,
  68         NFPROTO_IPV6   = 10,
  69         NFPROTO_DECNET = 12,
  70         NFPROTO_NUMPROTO,
  71 };
  72
  73 union nf_inet_addr {
  74         __u32           all[4];
  75         __be32          ip;
  76         __be32          ip6[4];
  77         struct in_addr  in;
  78         struct in6_addr in6;
  79 };
  80
  81 #ifdef __KERNEL__
  82 #ifdef CONFIG_NETFILTER
  83 static inline int NF_DROP_GETERR(int verdict)
  84 {
  85         return -(verdict >> NF_VERDICT_QBITS);
  86 }
  87
  88 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  89                                    const union nf_inet_addr *a2)
  90 {
  91         return a1->all[0] == a2->all[0] &&
  92                a1->all[1] == a2->all[1] &&
  93                a1->all[2] == a2->all[2] &&
  94                a1->all[3] == a2->all[3];
  95 }
  96
  97 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  98                                      union nf_inet_addr *result,
  99                                      const union nf_inet_addr *mask)
 100 {
 101         result->all[0] = a1->all[0] & mask->all[0];
 102         result->all[1] = a1->all[1] & mask->all[1];
 103         result->all[2] = a1->all[2] & mask->all[2];
 104         result->all[3] = a1->all[3] & mask->all[3];
 105 }
 106
 107 extern void netfilter_init(void);
 108
 109 /* Largest hook number + 1 */
 110 #define NF_MAX_HOOKS 8
 111
 112 struct sk_buff;
 113
 114 typedef unsigned int nf_hookfn(unsigned int hooknum,
 115                                struct sk_buff *skb,
 116                                const struct net_device *in,
 117                                const struct net_device *out,
 118                                int (*okfn)(struct sk_buff *));
 119
 120 struct nf_hook_ops {
 121         struct list_head list;
 122
 123         /* User fills in from here down. */
 124         nf_hookfn *hook;
 125         struct module *owner;
 126         u_int8_t pf;
 127         unsigned int hooknum;
 128         /* Hooks are ordered in ascending priority. */
 129         int priority;
 130 };
 131
 132 struct nf_sockopt_ops {
 133         struct list_head list;
 134
 135         u_int8_t pf;
 136
 137         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 138         int set_optmin;
 139         int set_optmax;
 140         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 141 #ifdef CONFIG_COMPAT
 142         int (*compat_set)(struct sock *sk, int optval,
 143                         void __user *user, unsigned int len);
 144 #endif
 145         int get_optmin;
 146         int get_optmax;
 147         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 148 #ifdef CONFIG_COMPAT
 149         int (*compat_get)(struct sock *sk, int optval,
 150                         void __user *user, int *len);
 151 #endif
 152         /* Use the module struct to lock set/get code in place */
 153         struct module *owner;
 154 };
 155
 156 /* Function to register/unregister hook points. */
 157 int nf_register_hook(struct nf_hook_ops *reg);
 158 void nf_unregister_hook(struct nf_hook_ops *reg);
 159 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 160 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 161
 162 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 163    need to check permissions yourself! */
 164 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 165 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 166
 167 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 168
 169 #if defined(CONFIG_JUMP_LABEL)
 170 #include <linux/static_key.h>
 171 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 172 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 173 {
 174         if (__builtin_constant_p(pf) &&
 175             __builtin_constant_p(hook))
 176                 return static_key_false(&nf_hooks_needed[pf][hook]);
 177
 178         return !list_empty(&nf_hooks[pf][hook]);
 179 }
 180 #else
 181 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 182 {
 183         return !list_empty(&nf_hooks[pf][hook]);
 184 }
 185 #endif
 186
 187 int nf_hook_slow(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 *), int thresh);
 190
 191 /**
 192  *      nf_hook_thresh - call a netfilter hook
 193  *
 194  *      Returns 1 if the hook has allowed the packet to pass.  The function
 195  *      okfn must be invoked by the caller in this case.  Any other return
 196  *      value indicates the packet has been consumed by the hook.
 197  */
 198 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 199                                  struct sk_buff *skb,
 200                                  struct net_device *indev,
 201                                  struct net_device *outdev,
 202                                  int (*okfn)(struct sk_buff *), int thresh)
 203 {
 204         if (nf_hooks_active(pf, hook))
 205                 return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 206         return 1;
 207 }
 208
 209 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 210                           struct net_device *indev, struct net_device *outdev,
 211                           int (*okfn)(struct sk_buff *))
 212 {
 213         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 214 }
 215
 216 /* Activate hook; either okfn or kfree_skb called, unless a hook
 217    returns NF_STOLEN (in which case, it's up to the hook to deal with
 218    the consequences).
 219
 220    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 221    accepted.
 222 */
 223
 224 /* RR:
 225    > I don't want nf_hook to return anything because people might forget
 226    > about async and trust the return value to mean "packet was ok".
 227
 228    AK:
 229    Just document it clearly, then you can expect some sense from kernel
 230    coders :)
 231 */
 232
 233 static inline int
 234 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 235                struct net_device *in, struct net_device *out,
 236                int (*okfn)(struct sk_buff *), int thresh)
 237 {
 238         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 239         if (ret == 1)
 240                 ret = okfn(skb);
 241         return ret;
 242 }
 243
 244 static inline int
 245 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 246              struct net_device *in, struct net_device *out,
 247              int (*okfn)(struct sk_buff *), bool cond)
 248 {
 249         int ret;
 250
 251         if (!cond ||
 252             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 253                 ret = okfn(skb);
 254         return ret;
 255 }
 256
 257 static inline int
 258 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 259         struct net_device *in, struct net_device *out,
 260         int (*okfn)(struct sk_buff *))
 261 {
 262         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 263 }
 264
 265 /* Call setsockopt() */
 266 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 267                   unsigned int len);
 268 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 269                   int *len);
 270 #ifdef CONFIG_COMPAT
 271 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 272                 char __user *opt, unsigned int len);
 273 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 274                 char __user *opt, int *len);
 275 #endif
 276
 277 /* Call this before modifying an existing packet: ensures it is
 278    modifiable and linear to the point you care about (writable_len).
 279    Returns true or false. */
 280 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 281
 282 struct flowi;
 283 struct nf_queue_entry;
 284
 285 struct nf_afinfo {
 286         unsigned short  family;
 287         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 288                                     unsigned int dataoff, u_int8_t protocol);
 289         __sum16         (*checksum_partial)(struct sk_buff *skb,
 290                                             unsigned int hook,
 291                                             unsigned int dataoff,
 292                                             unsigned int len,
 293                                             u_int8_t protocol);
 294         int             (*route)(struct net *net, struct dst_entry **dst,
 295                                  struct flowi *fl, bool strict);
 296         void            (*saveroute)(const struct sk_buff *skb,
 297                                      struct nf_queue_entry *entry);
 298         int             (*reroute)(struct sk_buff *skb,
 299                                    const struct nf_queue_entry *entry);
 300         int             route_key_size;
 301 };
 302
 303 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 304 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 305 {
 306         return rcu_dereference(nf_afinfo[family]);
 307 }
 308
 309 static inline __sum16
 310 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 311             u_int8_t protocol, unsigned short family)
 312 {
 313         const struct nf_afinfo *afinfo;
 314         __sum16 csum = 0;
 315
 316         rcu_read_lock();
 317         afinfo = nf_get_afinfo(family);
 318         if (afinfo)
 319                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 320         rcu_read_unlock();
 321         return csum;
 322 }
 323
 324 static inline __sum16
 325 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 326                     unsigned int dataoff, unsigned int len,
 327                     u_int8_t protocol, unsigned short family)
 328 {
 329         const struct nf_afinfo *afinfo;
 330         __sum16 csum = 0;
 331
 332         rcu_read_lock();
 333         afinfo = nf_get_afinfo(family);
 334         if (afinfo)
 335                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 336                                                 protocol);
 337         rcu_read_unlock();
 338         return csum;
 339 }
 340
 341 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 342 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 343
 344 #include <net/flow.h>
 345 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 346
 347 static inline void
 348 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 349 {
 350 #ifdef CONFIG_NF_NAT_NEEDED
 351         void (*decodefn)(struct sk_buff *, struct flowi *);
 352
 353         rcu_read_lock();
 354         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 355         if (decodefn)
 356                 decodefn(skb, fl);
 357         rcu_read_unlock();
 358 #endif
 359 }
 360
 361 #ifdef CONFIG_PROC_FS
 362 #include <linux/proc_fs.h>
 363 extern struct proc_dir_entry *proc_net_netfilter;
 364 #endif
 365
 366 #else /* !CONFIG_NETFILTER */
 367 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 368 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 369 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 370                                  struct sk_buff *skb,
 371                                  struct net_device *indev,
 372                                  struct net_device *outdev,
 373                                  int (*okfn)(struct sk_buff *), int thresh)
 374 {
 375         return okfn(skb);
 376 }
 377 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 378                           struct net_device *indev, struct net_device *outdev,
 379                           int (*okfn)(struct sk_buff *))
 380 {
 381         return 1;
 382 }
 383 struct flowi;
 384 static inline void
 385 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 386 {
 387 }
 388 #endif /*CONFIG_NETFILTER*/
 389
 390 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 391 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 392 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 393 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 394
 395 struct nf_conn;
 396 struct nlattr;
 397
 398 struct nfq_ct_hook {
 399         size_t (*build_size)(const struct nf_conn *ct);
 400         int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 401         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 402 };
 403 extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 404
 405 struct nfq_ct_nat_hook {
 406         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 407                            u32 ctinfo, int off);
 408 };
 409 extern struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook;
 410 #else
 411 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 412 #endif
 413
 414 #endif /*__KERNEL__*/
 415 #endif /*__LINUX_NETFILTER_H*/