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 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         int (*okfn)(struct sk_buff *);
  55 };
  56
  57 typedef unsigned int nf_hookfn(const struct nf_hook_ops *ops,
  58                                struct sk_buff *skb,
  59                                const struct nf_hook_state *state);
  60
  61 struct nf_hook_ops {
  62         struct list_head list;
  63
  64         /* User fills in from here down. */
  65         nf_hookfn       *hook;
  66         struct module   *owner;
  67         void            *priv;
  68         u_int8_t        pf;
  69         unsigned int    hooknum;
  70         /* Hooks are ordered in ascending priority. */
  71         int             priority;
  72 };
  73
  74 struct nf_sockopt_ops {
  75         struct list_head list;
  76
  77         u_int8_t pf;
  78
  79         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  80         int set_optmin;
  81         int set_optmax;
  82         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  83 #ifdef CONFIG_COMPAT
  84         int (*compat_set)(struct sock *sk, int optval,
  85                         void __user *user, unsigned int len);
  86 #endif
  87         int get_optmin;
  88         int get_optmax;
  89         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  90 #ifdef CONFIG_COMPAT
  91         int (*compat_get)(struct sock *sk, int optval,
  92                         void __user *user, int *len);
  93 #endif
  94         /* Use the module struct to lock set/get code in place */
  95         struct module *owner;
  96 };
  97
  98 /* Function to register/unregister hook points. */
  99 int nf_register_hook(struct nf_hook_ops *reg);
 100 void nf_unregister_hook(struct nf_hook_ops *reg);
 101 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 102 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 103
 104 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 105    need to check permissions yourself! */
 106 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 107 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 108
 109 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 110
 111 #ifdef HAVE_JUMP_LABEL
 112 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 113
 114 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 115 {
 116         if (__builtin_constant_p(pf) &&
 117             __builtin_constant_p(hook))
 118                 return static_key_false(&nf_hooks_needed[pf][hook]);
 119
 120         return !list_empty(&nf_hooks[pf][hook]);
 121 }
 122 #else
 123 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 124 {
 125         return !list_empty(&nf_hooks[pf][hook]);
 126 }
 127 #endif
 128
 129 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state);
 130
 131 /**
 132  *      nf_hook_thresh - call a netfilter hook
 133  *
 134  *      Returns 1 if the hook has allowed the packet to pass.  The function
 135  *      okfn must be invoked by the caller in this case.  Any other return
 136  *      value indicates the packet has been consumed by the hook.
 137  */
 138 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 139                                  struct sk_buff *skb,
 140                                  struct net_device *indev,
 141                                  struct net_device *outdev,
 142                                  int (*okfn)(struct sk_buff *), int thresh)
 143 {
 144         if (nf_hooks_active(pf, hook)) {
 145                 struct nf_hook_state state = {
 146                         .hook = hook,
 147                         .thresh = thresh,
 148                         .pf = pf,
 149                         .in = indev,
 150                         .out = outdev,
 151                         .okfn = okfn
 152                 };
 153
 154                 return nf_hook_slow(skb, &state);
 155         }
 156         return 1;
 157 }
 158
 159 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 160                           struct net_device *indev, struct net_device *outdev,
 161                           int (*okfn)(struct sk_buff *))
 162 {
 163         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 164 }
 165
 166 /* Activate hook; either okfn or kfree_skb called, unless a hook
 167    returns NF_STOLEN (in which case, it's up to the hook to deal with
 168    the consequences).
 169
 170    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 171    accepted.
 172 */
 173
 174 /* RR:
 175    > I don't want nf_hook to return anything because people might forget
 176    > about async and trust the return value to mean "packet was ok".
 177
 178    AK:
 179    Just document it clearly, then you can expect some sense from kernel
 180    coders :)
 181 */
 182
 183 static inline int
 184 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 185                struct net_device *in, struct net_device *out,
 186                int (*okfn)(struct sk_buff *), int thresh)
 187 {
 188         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 189         if (ret == 1)
 190                 ret = okfn(skb);
 191         return ret;
 192 }
 193
 194 static inline int
 195 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 196              struct net_device *in, struct net_device *out,
 197              int (*okfn)(struct sk_buff *), bool cond)
 198 {
 199         int ret;
 200
 201         if (!cond ||
 202             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 203                 ret = okfn(skb);
 204         return ret;
 205 }
 206
 207 static inline int
 208 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 209         struct net_device *in, struct net_device *out,
 210         int (*okfn)(struct sk_buff *))
 211 {
 212         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 213 }
 214
 215 /* Call setsockopt() */
 216 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 217                   unsigned int len);
 218 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 219                   int *len);
 220 #ifdef CONFIG_COMPAT
 221 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 222                 char __user *opt, unsigned int len);
 223 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 224                 char __user *opt, int *len);
 225 #endif
 226
 227 /* Call this before modifying an existing packet: ensures it is
 228    modifiable and linear to the point you care about (writable_len).
 229    Returns true or false. */
 230 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 231
 232 struct flowi;
 233 struct nf_queue_entry;
 234
 235 struct nf_afinfo {
 236         unsigned short  family;
 237         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 238                                     unsigned int dataoff, u_int8_t protocol);
 239         __sum16         (*checksum_partial)(struct sk_buff *skb,
 240                                             unsigned int hook,
 241                                             unsigned int dataoff,
 242                                             unsigned int len,
 243                                             u_int8_t protocol);
 244         int             (*route)(struct net *net, struct dst_entry **dst,
 245                                  struct flowi *fl, bool strict);
 246         void            (*saveroute)(const struct sk_buff *skb,
 247                                      struct nf_queue_entry *entry);
 248         int             (*reroute)(struct sk_buff *skb,
 249                                    const struct nf_queue_entry *entry);
 250         int             route_key_size;
 251 };
 252
 253 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 254 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 255 {
 256         return rcu_dereference(nf_afinfo[family]);
 257 }
 258
 259 static inline __sum16
 260 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 261             u_int8_t protocol, unsigned short family)
 262 {
 263         const struct nf_afinfo *afinfo;
 264         __sum16 csum = 0;
 265
 266         rcu_read_lock();
 267         afinfo = nf_get_afinfo(family);
 268         if (afinfo)
 269                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 270         rcu_read_unlock();
 271         return csum;
 272 }
 273
 274 static inline __sum16
 275 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 276                     unsigned int dataoff, unsigned int len,
 277                     u_int8_t protocol, unsigned short family)
 278 {
 279         const struct nf_afinfo *afinfo;
 280         __sum16 csum = 0;
 281
 282         rcu_read_lock();
 283         afinfo = nf_get_afinfo(family);
 284         if (afinfo)
 285                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 286                                                 protocol);
 287         rcu_read_unlock();
 288         return csum;
 289 }
 290
 291 int nf_register_afinfo(const struct nf_afinfo *afinfo);
 292 void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 293
 294 #include <net/flow.h>
 295 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 296
 297 static inline void
 298 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 299 {
 300 #ifdef CONFIG_NF_NAT_NEEDED
 301         void (*decodefn)(struct sk_buff *, struct flowi *);
 302
 303         rcu_read_lock();
 304         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 305         if (decodefn)
 306                 decodefn(skb, fl);
 307         rcu_read_unlock();
 308 #endif
 309 }
 310
 311 #else /* !CONFIG_NETFILTER */
 312 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 313 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 314 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 315                                  struct sk_buff *skb,
 316                                  struct net_device *indev,
 317                                  struct net_device *outdev,
 318                                  int (*okfn)(struct sk_buff *), int thresh)
 319 {
 320         return okfn(skb);
 321 }
 322 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 323                           struct net_device *indev, struct net_device *outdev,
 324                           int (*okfn)(struct sk_buff *))
 325 {
 326         return 1;
 327 }
 328 struct flowi;
 329 static inline void
 330 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 331 {
 332 }
 333 #endif /*CONFIG_NETFILTER*/
 334
 335 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 336 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 337 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 338 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 339
 340 struct nf_conn;
 341 enum ip_conntrack_info;
 342 struct nlattr;
 343
 344 struct nfq_ct_hook {
 345         size_t (*build_size)(const struct nf_conn *ct);
 346         int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 347         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 348         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 349                              u32 portid, u32 report);
 350         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 351                            enum ip_conntrack_info ctinfo, s32 off);
 352 };
 353 extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 354 #else
 355 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 356 #endif
 357
 358 #endif /*__LINUX_NETFILTER_H*/