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 <uapi/linux/netfilter.h>
  13 #ifdef CONFIG_NETFILTER
  14 static inline int NF_DROP_GETERR(int verdict)
  15 {
  16         return -(verdict >> NF_VERDICT_QBITS);
  17 }
  18
  19 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  20                                    const union nf_inet_addr *a2)
  21 {
  22         return a1->all[0] == a2->all[0] &&
  23                a1->all[1] == a2->all[1] &&
  24                a1->all[2] == a2->all[2] &&
  25                a1->all[3] == a2->all[3];
  26 }
  27
  28 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  29                                      union nf_inet_addr *result,
  30                                      const union nf_inet_addr *mask)
  31 {
  32         result->all[0] = a1->all[0] & mask->all[0];
  33         result->all[1] = a1->all[1] & mask->all[1];
  34         result->all[2] = a1->all[2] & mask->all[2];
  35         result->all[3] = a1->all[3] & mask->all[3];
  36 }
  37
  38 extern void netfilter_init(void);
  39
  40 /* Largest hook number + 1 */
  41 #define NF_MAX_HOOKS 8
  42
  43 struct sk_buff;
  44
  45 typedef unsigned int nf_hookfn(unsigned int hooknum,
  46                                struct sk_buff *skb,
  47                                const struct net_device *in,
  48                                const struct net_device *out,
  49                                int (*okfn)(struct sk_buff *));
  50
  51 struct nf_hook_ops {
  52         struct list_head list;
  53
  54         /* User fills in from here down. */
  55         nf_hookfn *hook;
  56         struct module *owner;
  57         u_int8_t pf;
  58         unsigned int hooknum;
  59         /* Hooks are ordered in ascending priority. */
  60         int priority;
  61 };
  62
  63 struct nf_sockopt_ops {
  64         struct list_head list;
  65
  66         u_int8_t pf;
  67
  68         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  69         int set_optmin;
  70         int set_optmax;
  71         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  72 #ifdef CONFIG_COMPAT
  73         int (*compat_set)(struct sock *sk, int optval,
  74                         void __user *user, unsigned int len);
  75 #endif
  76         int get_optmin;
  77         int get_optmax;
  78         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  79 #ifdef CONFIG_COMPAT
  80         int (*compat_get)(struct sock *sk, int optval,
  81                         void __user *user, int *len);
  82 #endif
  83         /* Use the module struct to lock set/get code in place */
  84         struct module *owner;
  85 };
  86
  87 /* Function to register/unregister hook points. */
  88 int nf_register_hook(struct nf_hook_ops *reg);
  89 void nf_unregister_hook(struct nf_hook_ops *reg);
  90 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
  91 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
  92
  93 /* Functions to register get/setsockopt ranges (non-inclusive).  You
  94    need to check permissions yourself! */
  95 int nf_register_sockopt(struct nf_sockopt_ops *reg);
  96 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
  97
  98 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
  99
 100 #if defined(CONFIG_JUMP_LABEL)
 101 #include <linux/static_key.h>
 102 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 103 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 104 {
 105         if (__builtin_constant_p(pf) &&
 106             __builtin_constant_p(hook))
 107                 return static_key_false(&nf_hooks_needed[pf][hook]);
 108
 109         return !list_empty(&nf_hooks[pf][hook]);
 110 }
 111 #else
 112 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 113 {
 114         return !list_empty(&nf_hooks[pf][hook]);
 115 }
 116 #endif
 117
 118 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 119                  struct net_device *indev, struct net_device *outdev,
 120                  int (*okfn)(struct sk_buff *), int thresh);
 121
 122 /**
 123  *      nf_hook_thresh - call a netfilter hook
 124  *
 125  *      Returns 1 if the hook has allowed the packet to pass.  The function
 126  *      okfn must be invoked by the caller in this case.  Any other return
 127  *      value indicates the packet has been consumed by the hook.
 128  */
 129 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 130                                  struct sk_buff *skb,
 131                                  struct net_device *indev,
 132                                  struct net_device *outdev,
 133                                  int (*okfn)(struct sk_buff *), int thresh)
 134 {
 135         if (nf_hooks_active(pf, hook))
 136                 return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 137         return 1;
 138 }
 139
 140 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 141                           struct net_device *indev, struct net_device *outdev,
 142                           int (*okfn)(struct sk_buff *))
 143 {
 144         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 145 }
 146
 147 /* Activate hook; either okfn or kfree_skb called, unless a hook
 148    returns NF_STOLEN (in which case, it's up to the hook to deal with
 149    the consequences).
 150
 151    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 152    accepted.
 153 */
 154
 155 /* RR:
 156    > I don't want nf_hook to return anything because people might forget
 157    > about async and trust the return value to mean "packet was ok".
 158
 159    AK:
 160    Just document it clearly, then you can expect some sense from kernel
 161    coders :)
 162 */
 163
 164 static inline int
 165 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 166                struct net_device *in, struct net_device *out,
 167                int (*okfn)(struct sk_buff *), int thresh)
 168 {
 169         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 170         if (ret == 1)
 171                 ret = okfn(skb);
 172         return ret;
 173 }
 174
 175 static inline int
 176 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 177              struct net_device *in, struct net_device *out,
 178              int (*okfn)(struct sk_buff *), bool cond)
 179 {
 180         int ret;
 181
 182         if (!cond ||
 183             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 184                 ret = okfn(skb);
 185         return ret;
 186 }
 187
 188 static inline int
 189 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 190         struct net_device *in, struct net_device *out,
 191         int (*okfn)(struct sk_buff *))
 192 {
 193         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 194 }
 195
 196 /* Call setsockopt() */
 197 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 198                   unsigned int len);
 199 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 200                   int *len);
 201 #ifdef CONFIG_COMPAT
 202 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 203                 char __user *opt, unsigned int len);
 204 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 205                 char __user *opt, int *len);
 206 #endif
 207
 208 /* Call this before modifying an existing packet: ensures it is
 209    modifiable and linear to the point you care about (writable_len).
 210    Returns true or false. */
 211 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 212
 213 struct flowi;
 214 struct nf_queue_entry;
 215
 216 struct nf_afinfo {
 217         unsigned short  family;
 218         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 219                                     unsigned int dataoff, u_int8_t protocol);
 220         __sum16         (*checksum_partial)(struct sk_buff *skb,
 221                                             unsigned int hook,
 222                                             unsigned int dataoff,
 223                                             unsigned int len,
 224                                             u_int8_t protocol);
 225         int             (*route)(struct net *net, struct dst_entry **dst,
 226                                  struct flowi *fl, bool strict);
 227         void            (*saveroute)(const struct sk_buff *skb,
 228                                      struct nf_queue_entry *entry);
 229         int             (*reroute)(struct sk_buff *skb,
 230                                    const struct nf_queue_entry *entry);
 231         int             route_key_size;
 232 };
 233
 234 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 235 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 236 {
 237         return rcu_dereference(nf_afinfo[family]);
 238 }
 239
 240 static inline __sum16
 241 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 242             u_int8_t protocol, unsigned short family)
 243 {
 244         const struct nf_afinfo *afinfo;
 245         __sum16 csum = 0;
 246
 247         rcu_read_lock();
 248         afinfo = nf_get_afinfo(family);
 249         if (afinfo)
 250                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 251         rcu_read_unlock();
 252         return csum;
 253 }
 254
 255 static inline __sum16
 256 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 257                     unsigned int dataoff, unsigned int len,
 258                     u_int8_t protocol, unsigned short family)
 259 {
 260         const struct nf_afinfo *afinfo;
 261         __sum16 csum = 0;
 262
 263         rcu_read_lock();
 264         afinfo = nf_get_afinfo(family);
 265         if (afinfo)
 266                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 267                                                 protocol);
 268         rcu_read_unlock();
 269         return csum;
 270 }
 271
 272 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 273 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 274
 275 #include <net/flow.h>
 276 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 277
 278 static inline void
 279 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 280 {
 281 #ifdef CONFIG_NF_NAT_NEEDED
 282         void (*decodefn)(struct sk_buff *, struct flowi *);
 283
 284         rcu_read_lock();
 285         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 286         if (decodefn)
 287                 decodefn(skb, fl);
 288         rcu_read_unlock();
 289 #endif
 290 }
 291
 292 #else /* !CONFIG_NETFILTER */
 293 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 294 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 295 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 296                                  struct sk_buff *skb,
 297                                  struct net_device *indev,
 298                                  struct net_device *outdev,
 299                                  int (*okfn)(struct sk_buff *), int thresh)
 300 {
 301         return okfn(skb);
 302 }
 303 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 304                           struct net_device *indev, struct net_device *outdev,
 305                           int (*okfn)(struct sk_buff *))
 306 {
 307         return 1;
 308 }
 309 struct flowi;
 310 static inline void
 311 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 312 {
 313 }
 314 #endif /*CONFIG_NETFILTER*/
 315
 316 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 317 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 318 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 319 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 320
 321 struct nf_conn;
 322 struct nlattr;
 323
 324 struct nfq_ct_hook {
 325         size_t (*build_size)(const struct nf_conn *ct);
 326         int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 327         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 328 };
 329 extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 330
 331 struct nfq_ct_nat_hook {
 332         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 333                            u32 ctinfo, int off);
 334 };
 335 extern struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook;
 336 #else
 337 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 338 #endif
 339
 340 #endif /*__LINUX_NETFILTER_H*/