include/linux/netfilter.h

   1 #ifndef __LINUX_NETFILTER_H
   2 #define __LINUX_NETFILTER_H
   3
   4 #include <linux/init.h>
   5 #include <linux/skbuff.h>
   6 #include <linux/net.h>
   7 #include <linux/if.h>
   8 #include <linux/in.h>
   9 #include <linux/in6.h>
  10 #include <linux/wait.h>
  11 #include <linux/list.h>
  12 #include <linux/static_key.h>
  13 #include <linux/netfilter_defs.h>
  14
  15 #ifdef CONFIG_NETFILTER
  16 static inline int NF_DROP_GETERR(int verdict)
  17 {
  18         return -(verdict >> NF_VERDICT_QBITS);
  19 }
  20
  21 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  22                                    const union nf_inet_addr *a2)
  23 {
  24         return a1->all[0] == a2->all[0] &&
  25                a1->all[1] == a2->all[1] &&
  26                a1->all[2] == a2->all[2] &&
  27                a1->all[3] == a2->all[3];
  28 }
  29
  30 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  31                                      union nf_inet_addr *result,
  32                                      const union nf_inet_addr *mask)
  33 {
  34         result->all[0] = a1->all[0] & mask->all[0];
  35         result->all[1] = a1->all[1] & mask->all[1];
  36         result->all[2] = a1->all[2] & mask->all[2];
  37         result->all[3] = a1->all[3] & mask->all[3];
  38 }
  39
  40 int netfilter_init(void);
  41
  42 struct sk_buff;
  43
  44 struct nf_hook_ops;
  45
  46 struct sock;
  47
  48 struct nf_hook_state {
  49         unsigned int hook;
  50         int thresh;
  51         u_int8_t pf;
  52         struct net_device *in;
  53         struct net_device *out;
  54         struct sock *sk;
  55         struct list_head *hook_list;
  56         int (*okfn)(struct sock *, struct sk_buff *);
  57 };
  58
  59 static inline void nf_hook_state_init(struct nf_hook_state *p,
  60                                       struct list_head *hook_list,
  61                                       unsigned int hook,
  62                                       int thresh, u_int8_t pf,
  63                                       struct net_device *indev,
  64                                       struct net_device *outdev,
  65                                       struct sock *sk,
  66                                       int (*okfn)(struct sock *, struct sk_buff *))
  67 {
  68         p->hook = hook;
  69         p->thresh = thresh;
  70         p->pf = pf;
  71         p->in = indev;
  72         p->out = outdev;
  73         p->sk = sk;
  74         p->hook_list = hook_list;
  75         p->okfn = okfn;
  76 }
  77
  78 typedef unsigned int nf_hookfn(const struct nf_hook_ops *ops,
  79                                struct sk_buff *skb,
  80                                const struct nf_hook_state *state);
  81
  82 struct nf_hook_ops {
  83         struct list_head        list;
  84
  85         /* User fills in from here down. */
  86         nf_hookfn               *hook;
  87         struct net_device       *dev;
  88         struct module           *owner;
  89         void                    *priv;
  90         u_int8_t                pf;
  91         unsigned int            hooknum;
  92         /* Hooks are ordered in ascending priority. */
  93         int                     priority;
  94 };
  95
  96 struct nf_sockopt_ops {
  97         struct list_head list;
  98
  99         u_int8_t pf;
 100
 101         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 102         int set_optmin;
 103         int set_optmax;
 104         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 105 #ifdef CONFIG_COMPAT
 106         int (*compat_set)(struct sock *sk, int optval,
 107                         void __user *user, unsigned int len);
 108 #endif
 109         int get_optmin;
 110         int get_optmax;
 111         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 112 #ifdef CONFIG_COMPAT
 113         int (*compat_get)(struct sock *sk, int optval,
 114                         void __user *user, int *len);
 115 #endif
 116         /* Use the module struct to lock set/get code in place */
 117         struct module *owner;
 118 };
 119
 120 /* Function to register/unregister hook points. */
 121 int nf_register_hook(struct nf_hook_ops *reg);
 122 void nf_unregister_hook(struct nf_hook_ops *reg);
 123 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 124 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 125
 126 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 127    need to check permissions yourself! */
 128 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 129 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 130
 131 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 132
 133 #ifdef HAVE_JUMP_LABEL
 134 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 135
 136 static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
 137                                        u_int8_t pf, unsigned int hook)
 138 {
 139         if (__builtin_constant_p(pf) &&
 140             __builtin_constant_p(hook))
 141                 return static_key_false(&nf_hooks_needed[pf][hook]);
 142
 143         return !list_empty(nf_hook_list);
 144 }
 145 #else
 146 static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
 147                                        u_int8_t pf, unsigned int hook)
 148 {
 149         return !list_empty(nf_hook_list);
 150 }
 151 #endif
 152
 153 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 154 {
 155         return nf_hook_list_active(&nf_hooks[pf][hook], pf, hook);
 156 }
 157
 158 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state);
 159
 160 /**
 161  *      nf_hook_thresh - call a netfilter hook
 162  *
 163  *      Returns 1 if the hook has allowed the packet to pass.  The function
 164  *      okfn must be invoked by the caller in this case.  Any other return
 165  *      value indicates the packet has been consumed by the hook.
 166  */
 167 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 168                                  struct sock *sk,
 169                                  struct sk_buff *skb,
 170                                  struct net_device *indev,
 171                                  struct net_device *outdev,
 172                                  int (*okfn)(struct sock *, struct sk_buff *),
 173                                  int thresh)
 174 {
 175         if (nf_hooks_active(pf, hook)) {
 176                 struct nf_hook_state state;
 177
 178                 nf_hook_state_init(&state, &nf_hooks[pf][hook], hook, thresh,
 179                                    pf, indev, outdev, sk, okfn);
 180                 return nf_hook_slow(skb, &state);
 181         }
 182         return 1;
 183 }
 184
 185 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
 186                           struct sk_buff *skb, struct net_device *indev,
 187                           struct net_device *outdev,
 188                           int (*okfn)(struct sock *, struct sk_buff *))
 189 {
 190         return nf_hook_thresh(pf, hook, sk, skb, indev, outdev, okfn, INT_MIN);
 191 }
 192
 193 /* Activate hook; either okfn or kfree_skb called, unless a hook
 194    returns NF_STOLEN (in which case, it's up to the hook to deal with
 195    the consequences).
 196
 197    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 198    accepted.
 199 */
 200
 201 /* RR:
 202    > I don't want nf_hook to return anything because people might forget
 203    > about async and trust the return value to mean "packet was ok".
 204
 205    AK:
 206    Just document it clearly, then you can expect some sense from kernel
 207    coders :)
 208 */
 209
 210 static inline int
 211 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sock *sk,
 212                struct sk_buff *skb, struct net_device *in,
 213                struct net_device *out,
 214                int (*okfn)(struct sock *, struct sk_buff *), int thresh)
 215 {
 216         int ret = nf_hook_thresh(pf, hook, sk, skb, in, out, okfn, thresh);
 217         if (ret == 1)
 218                 ret = okfn(sk, skb);
 219         return ret;
 220 }
 221
 222 static inline int
 223 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sock *sk,
 224              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 225              int (*okfn)(struct sock *, struct sk_buff *), bool cond)
 226 {
 227         int ret;
 228
 229         if (!cond ||
 230             ((ret = nf_hook_thresh(pf, hook, sk, skb, in, out, okfn, INT_MIN)) == 1))
 231                 ret = okfn(sk, skb);
 232         return ret;
 233 }
 234
 235 static inline int
 236 NF_HOOK(uint8_t pf, unsigned int hook, struct sock *sk, struct sk_buff *skb,
 237         struct net_device *in, struct net_device *out,
 238         int (*okfn)(struct sock *, struct sk_buff *))
 239 {
 240         return NF_HOOK_THRESH(pf, hook, sk, 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 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 net *net, struct dst_entry **dst,
 273                                  struct flowi *fl, bool strict);
 274         void            (*saveroute)(const struct sk_buff *skb,
 275                                      struct nf_queue_entry *entry);
 276         int             (*reroute)(struct sk_buff *skb,
 277                                    const struct nf_queue_entry *entry);
 278         int             route_key_size;
 279 };
 280
 281 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 282 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 283 {
 284         return rcu_dereference(nf_afinfo[family]);
 285 }
 286
 287 static inline __sum16
 288 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 289             u_int8_t protocol, unsigned short family)
 290 {
 291         const struct nf_afinfo *afinfo;
 292         __sum16 csum = 0;
 293
 294         rcu_read_lock();
 295         afinfo = nf_get_afinfo(family);
 296         if (afinfo)
 297                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 298         rcu_read_unlock();
 299         return csum;
 300 }
 301
 302 static inline __sum16
 303 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 304                     unsigned int dataoff, unsigned int len,
 305                     u_int8_t protocol, unsigned short family)
 306 {
 307         const struct nf_afinfo *afinfo;
 308         __sum16 csum = 0;
 309
 310         rcu_read_lock();
 311         afinfo = nf_get_afinfo(family);
 312         if (afinfo)
 313                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 314                                                 protocol);
 315         rcu_read_unlock();
 316         return csum;
 317 }
 318
 319 int nf_register_afinfo(const struct nf_afinfo *afinfo);
 320 void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 321
 322 #include <net/flow.h>
 323 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 324
 325 static inline void
 326 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 327 {
 328 #ifdef CONFIG_NF_NAT_NEEDED
 329         void (*decodefn)(struct sk_buff *, struct flowi *);
 330
 331         rcu_read_lock();
 332         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 333         if (decodefn)
 334                 decodefn(skb, fl);
 335         rcu_read_unlock();
 336 #endif
 337 }
 338
 339 #else /* !CONFIG_NETFILTER */
 340 #define NF_HOOK(pf, hook, sk, skb, indev, outdev, okfn) (okfn)(sk, skb)
 341 #define NF_HOOK_COND(pf, hook, sk, skb, indev, outdev, okfn, cond) (okfn)(sk, skb)
 342 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 343                                  struct sock *sk,
 344                                  struct sk_buff *skb,
 345                                  struct net_device *indev,
 346                                  struct net_device *outdev,
 347                                  int (*okfn)(struct sock *sk, struct sk_buff *), int thresh)
 348 {
 349         return okfn(sk, skb);
 350 }
 351 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
 352                           struct sk_buff *skb, struct net_device *indev,
 353                           struct net_device *outdev,
 354                           int (*okfn)(struct sock *, struct sk_buff *))
 355 {
 356         return 1;
 357 }
 358 struct flowi;
 359 static inline void
 360 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 361 {
 362 }
 363 #endif /*CONFIG_NETFILTER*/
 364
 365 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 366 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 367 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 368 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 369
 370 struct nf_conn;
 371 enum ip_conntrack_info;
 372 struct nlattr;
 373
 374 struct nfq_ct_hook {
 375         size_t (*build_size)(const struct nf_conn *ct);
 376         int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 377         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 378         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 379                              u32 portid, u32 report);
 380         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 381                            enum ip_conntrack_info ctinfo, s32 off);
 382 };
 383 extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 384 #else
 385 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 386 #endif
 387
 388 #endif /*__LINUX_NETFILTER_H*/