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 <uapi/linux/netfilter.h>
  14 #ifdef CONFIG_NETFILTER
  15 static inline int NF_DROP_GETERR(int verdict)
  16 {
  17         return -(verdict >> NF_VERDICT_QBITS);
  18 }
  19
  20 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  21                                    const union nf_inet_addr *a2)
  22 {
  23         return a1->all[0] == a2->all[0] &&
  24                a1->all[1] == a2->all[1] &&
  25                a1->all[2] == a2->all[2] &&
  26                a1->all[3] == a2->all[3];
  27 }
  28
  29 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  30                                      union nf_inet_addr *result,
  31                                      const union nf_inet_addr *mask)
  32 {
  33         result->all[0] = a1->all[0] & mask->all[0];
  34         result->all[1] = a1->all[1] & mask->all[1];
  35         result->all[2] = a1->all[2] & mask->all[2];
  36         result->all[3] = a1->all[3] & mask->all[3];
  37 }
  38
  39 int netfilter_init(void);
  40
  41 /* Largest hook number + 1 */
  42 #define NF_MAX_HOOKS 8
  43
  44 struct sk_buff;
  45
  46 struct nf_hook_ops;
  47
  48 struct sock;
  49
  50 struct nf_hook_state {
  51         unsigned int hook;
  52         int thresh;
  53         u_int8_t pf;
  54         struct net_device *in;
  55         struct net_device *out;
  56         struct sock *sk;
  57         int (*okfn)(struct sock *, struct sk_buff *);
  58 };
  59
  60 static inline void nf_hook_state_init(struct nf_hook_state *p,
  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->okfn = okfn;
  75 }
  76
  77 typedef unsigned int nf_hookfn(const struct nf_hook_ops *ops,
  78                                struct sk_buff *skb,
  79                                const struct nf_hook_state *state);
  80
  81 struct nf_hook_ops {
  82         struct list_head list;
  83
  84         /* User fills in from here down. */
  85         nf_hookfn       *hook;
  86         struct module   *owner;
  87         void            *priv;
  88         u_int8_t        pf;
  89         unsigned int    hooknum;
  90         /* Hooks are ordered in ascending priority. */
  91         int             priority;
  92 };
  93
  94 struct nf_sockopt_ops {
  95         struct list_head list;
  96
  97         u_int8_t pf;
  98
  99         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 100         int set_optmin;
 101         int set_optmax;
 102         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 103 #ifdef CONFIG_COMPAT
 104         int (*compat_set)(struct sock *sk, int optval,
 105                         void __user *user, unsigned int len);
 106 #endif
 107         int get_optmin;
 108         int get_optmax;
 109         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 110 #ifdef CONFIG_COMPAT
 111         int (*compat_get)(struct sock *sk, int optval,
 112                         void __user *user, int *len);
 113 #endif
 114         /* Use the module struct to lock set/get code in place */
 115         struct module *owner;
 116 };
 117
 118 /* Function to register/unregister hook points. */
 119 int nf_register_hook(struct nf_hook_ops *reg);
 120 void nf_unregister_hook(struct nf_hook_ops *reg);
 121 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 122 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 123
 124 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 125    need to check permissions yourself! */
 126 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 127 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 128
 129 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 130
 131 #ifdef HAVE_JUMP_LABEL
 132 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 133
 134 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 135 {
 136         if (__builtin_constant_p(pf) &&
 137             __builtin_constant_p(hook))
 138                 return static_key_false(&nf_hooks_needed[pf][hook]);
 139
 140         return !list_empty(&nf_hooks[pf][hook]);
 141 }
 142 #else
 143 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 144 {
 145         return !list_empty(&nf_hooks[pf][hook]);
 146 }
 147 #endif
 148
 149 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state);
 150
 151 /**
 152  *      nf_hook_thresh - call a netfilter hook
 153  *
 154  *      Returns 1 if the hook has allowed the packet to pass.  The function
 155  *      okfn must be invoked by the caller in this case.  Any other return
 156  *      value indicates the packet has been consumed by the hook.
 157  */
 158 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 159                                  struct sock *sk,
 160                                  struct sk_buff *skb,
 161                                  struct net_device *indev,
 162                                  struct net_device *outdev,
 163                                  int (*okfn)(struct sock *, struct sk_buff *),
 164                                  int thresh)
 165 {
 166         if (nf_hooks_active(pf, hook)) {
 167                 struct nf_hook_state state;
 168
 169                 nf_hook_state_init(&state, hook, thresh, pf,
 170                                    indev, outdev, sk, okfn);
 171                 return nf_hook_slow(skb, &state);
 172         }
 173         return 1;
 174 }
 175
 176 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
 177                           struct sk_buff *skb, struct net_device *indev,
 178                           struct net_device *outdev,
 179                           int (*okfn)(struct sock *, struct sk_buff *))
 180 {
 181         return nf_hook_thresh(pf, hook, sk, skb, indev, outdev, okfn, INT_MIN);
 182 }
 183
 184 /* Activate hook; either okfn or kfree_skb called, unless a hook
 185    returns NF_STOLEN (in which case, it's up to the hook to deal with
 186    the consequences).
 187
 188    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 189    accepted.
 190 */
 191
 192 /* RR:
 193    > I don't want nf_hook to return anything because people might forget
 194    > about async and trust the return value to mean "packet was ok".
 195
 196    AK:
 197    Just document it clearly, then you can expect some sense from kernel
 198    coders :)
 199 */
 200
 201 static inline int
 202 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sock *sk,
 203                struct sk_buff *skb, struct net_device *in,
 204                struct net_device *out,
 205                int (*okfn)(struct sock *, struct sk_buff *), int thresh)
 206 {
 207         int ret = nf_hook_thresh(pf, hook, sk, skb, in, out, okfn, thresh);
 208         if (ret == 1)
 209                 ret = okfn(sk, skb);
 210         return ret;
 211 }
 212
 213 static inline int
 214 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sock *sk,
 215              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 216              int (*okfn)(struct sock *, struct sk_buff *), bool cond)
 217 {
 218         int ret;
 219
 220         if (!cond ||
 221             ((ret = nf_hook_thresh(pf, hook, sk, skb, in, out, okfn, INT_MIN)) == 1))
 222                 ret = okfn(sk, skb);
 223         return ret;
 224 }
 225
 226 static inline int
 227 NF_HOOK(uint8_t pf, unsigned int hook, struct sock *sk, struct sk_buff *skb,
 228         struct net_device *in, struct net_device *out,
 229         int (*okfn)(struct sock *, struct sk_buff *))
 230 {
 231         return NF_HOOK_THRESH(pf, hook, sk, skb, in, out, okfn, INT_MIN);
 232 }
 233
 234 /* Call setsockopt() */
 235 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 236                   unsigned int len);
 237 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 238                   int *len);
 239 #ifdef CONFIG_COMPAT
 240 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 241                 char __user *opt, unsigned int len);
 242 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 243                 char __user *opt, int *len);
 244 #endif
 245
 246 /* Call this before modifying an existing packet: ensures it is
 247    modifiable and linear to the point you care about (writable_len).
 248    Returns true or false. */
 249 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 250
 251 struct flowi;
 252 struct nf_queue_entry;
 253
 254 struct nf_afinfo {
 255         unsigned short  family;
 256         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 257                                     unsigned int dataoff, u_int8_t protocol);
 258         __sum16         (*checksum_partial)(struct sk_buff *skb,
 259                                             unsigned int hook,
 260                                             unsigned int dataoff,
 261                                             unsigned int len,
 262                                             u_int8_t protocol);
 263         int             (*route)(struct net *net, struct dst_entry **dst,
 264                                  struct flowi *fl, bool strict);
 265         void            (*saveroute)(const struct sk_buff *skb,
 266                                      struct nf_queue_entry *entry);
 267         int             (*reroute)(struct sk_buff *skb,
 268                                    const struct nf_queue_entry *entry);
 269         int             route_key_size;
 270 };
 271
 272 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 273 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 274 {
 275         return rcu_dereference(nf_afinfo[family]);
 276 }
 277
 278 static inline __sum16
 279 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 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(skb, hook, dataoff, protocol);
 289         rcu_read_unlock();
 290         return csum;
 291 }
 292
 293 static inline __sum16
 294 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 295                     unsigned int dataoff, unsigned int len,
 296                     u_int8_t protocol, unsigned short family)
 297 {
 298         const struct nf_afinfo *afinfo;
 299         __sum16 csum = 0;
 300
 301         rcu_read_lock();
 302         afinfo = nf_get_afinfo(family);
 303         if (afinfo)
 304                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 305                                                 protocol);
 306         rcu_read_unlock();
 307         return csum;
 308 }
 309
 310 int nf_register_afinfo(const struct nf_afinfo *afinfo);
 311 void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 312
 313 #include <net/flow.h>
 314 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 315
 316 static inline void
 317 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 318 {
 319 #ifdef CONFIG_NF_NAT_NEEDED
 320         void (*decodefn)(struct sk_buff *, struct flowi *);
 321
 322         rcu_read_lock();
 323         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 324         if (decodefn)
 325                 decodefn(skb, fl);
 326         rcu_read_unlock();
 327 #endif
 328 }
 329
 330 #else /* !CONFIG_NETFILTER */
 331 #define NF_HOOK(pf, hook, sk, skb, indev, outdev, okfn) (okfn)(sk, skb)
 332 #define NF_HOOK_COND(pf, hook, sk, skb, indev, outdev, okfn, cond) (okfn)(sk, skb)
 333 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 334                                  struct sock *sk,
 335                                  struct sk_buff *skb,
 336                                  struct net_device *indev,
 337                                  struct net_device *outdev,
 338                                  int (*okfn)(struct sock *sk, struct sk_buff *), int thresh)
 339 {
 340         return okfn(sk, skb);
 341 }
 342 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
 343                           struct sk_buff *skb, struct net_device *indev,
 344                           struct net_device *outdev,
 345                           int (*okfn)(struct sock *, struct sk_buff *))
 346 {
 347         return 1;
 348 }
 349 struct flowi;
 350 static inline void
 351 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 352 {
 353 }
 354 #endif /*CONFIG_NETFILTER*/
 355
 356 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 357 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 358 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 359 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 360
 361 struct nf_conn;
 362 enum ip_conntrack_info;
 363 struct nlattr;
 364
 365 struct nfq_ct_hook {
 366         size_t (*build_size)(const struct nf_conn *ct);
 367         int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 368         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 369         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 370                              u32 portid, u32 report);
 371         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 372                            enum ip_conntrack_info ctinfo, s32 off);
 373 };
 374 extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 375 #else
 376 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 377 #endif
 378
 379 #endif /*__LINUX_NETFILTER_H*/