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 int netfilter_init(void);
  39
  40 /* Largest hook number + 1 */
  41 #define NF_MAX_HOOKS 8
  42
  43 struct sk_buff;
  44
  45 struct nf_hook_ops;
  46 typedef unsigned int nf_hookfn(const struct nf_hook_ops *ops,
  47                                struct sk_buff *skb,
  48                                const struct net_device *in,
  49                                const struct net_device *out,
  50                                int (*okfn)(struct sk_buff *));
  51
  52 struct nf_hook_ops {
  53         struct list_head list;
  54
  55         /* User fills in from here down. */
  56         nf_hookfn       *hook;
  57         struct module   *owner;
  58         void            *priv;
  59         u_int8_t        pf;
  60         unsigned int    hooknum;
  61         /* Hooks are ordered in ascending priority. */
  62         int             priority;
  63 };
  64
  65 struct nf_sockopt_ops {
  66         struct list_head list;
  67
  68         u_int8_t pf;
  69
  70         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  71         int set_optmin;
  72         int set_optmax;
  73         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  74 #ifdef CONFIG_COMPAT
  75         int (*compat_set)(struct sock *sk, int optval,
  76                         void __user *user, unsigned int len);
  77 #endif
  78         int get_optmin;
  79         int get_optmax;
  80         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  81 #ifdef CONFIG_COMPAT
  82         int (*compat_get)(struct sock *sk, int optval,
  83                         void __user *user, int *len);
  84 #endif
  85         /* Use the module struct to lock set/get code in place */
  86         struct module *owner;
  87 };
  88
  89 /* Function to register/unregister hook points. */
  90 int nf_register_hook(struct nf_hook_ops *reg);
  91 void nf_unregister_hook(struct nf_hook_ops *reg);
  92 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
  93 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
  94
  95 /* Functions to register get/setsockopt ranges (non-inclusive).  You
  96    need to check permissions yourself! */
  97 int nf_register_sockopt(struct nf_sockopt_ops *reg);
  98 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
  99
 100 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 101
 102 #if defined(CONFIG_JUMP_LABEL)
 103 #include <linux/static_key.h>
 104 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 105 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 106 {
 107         if (__builtin_constant_p(pf) &&
 108             __builtin_constant_p(hook))
 109                 return static_key_false(&nf_hooks_needed[pf][hook]);
 110
 111         return !list_empty(&nf_hooks[pf][hook]);
 112 }
 113 #else
 114 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 115 {
 116         return !list_empty(&nf_hooks[pf][hook]);
 117 }
 118 #endif
 119
 120 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 121                  struct net_device *indev, struct net_device *outdev,
 122                  int (*okfn)(struct sk_buff *), int thresh);
 123
 124 /**
 125  *      nf_hook_thresh - call a netfilter hook
 126  *
 127  *      Returns 1 if the hook has allowed the packet to pass.  The function
 128  *      okfn must be invoked by the caller in this case.  Any other return
 129  *      value indicates the packet has been consumed by the hook.
 130  */
 131 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 132                                  struct sk_buff *skb,
 133                                  struct net_device *indev,
 134                                  struct net_device *outdev,
 135                                  int (*okfn)(struct sk_buff *), int thresh)
 136 {
 137         if (nf_hooks_active(pf, hook))
 138                 return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 139         return 1;
 140 }
 141
 142 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 143                           struct net_device *indev, struct net_device *outdev,
 144                           int (*okfn)(struct sk_buff *))
 145 {
 146         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 147 }
 148
 149 /* Activate hook; either okfn or kfree_skb called, unless a hook
 150    returns NF_STOLEN (in which case, it's up to the hook to deal with
 151    the consequences).
 152
 153    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 154    accepted.
 155 */
 156
 157 /* RR:
 158    > I don't want nf_hook to return anything because people might forget
 159    > about async and trust the return value to mean "packet was ok".
 160
 161    AK:
 162    Just document it clearly, then you can expect some sense from kernel
 163    coders :)
 164 */
 165
 166 static inline int
 167 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 168                struct net_device *in, struct net_device *out,
 169                int (*okfn)(struct sk_buff *), int thresh)
 170 {
 171         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 172         if (ret == 1)
 173                 ret = okfn(skb);
 174         return ret;
 175 }
 176
 177 static inline int
 178 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 179              struct net_device *in, struct net_device *out,
 180              int (*okfn)(struct sk_buff *), bool cond)
 181 {
 182         int ret;
 183
 184         if (!cond ||
 185             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 186                 ret = okfn(skb);
 187         return ret;
 188 }
 189
 190 static inline int
 191 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 192         struct net_device *in, struct net_device *out,
 193         int (*okfn)(struct sk_buff *))
 194 {
 195         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 196 }
 197
 198 /* Call setsockopt() */
 199 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 200                   unsigned int len);
 201 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 202                   int *len);
 203 #ifdef CONFIG_COMPAT
 204 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 205                 char __user *opt, unsigned int len);
 206 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 207                 char __user *opt, int *len);
 208 #endif
 209
 210 /* Call this before modifying an existing packet: ensures it is
 211    modifiable and linear to the point you care about (writable_len).
 212    Returns true or false. */
 213 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 214
 215 struct flowi;
 216 struct nf_queue_entry;
 217
 218 struct nf_afinfo {
 219         unsigned short  family;
 220         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 221                                     unsigned int dataoff, u_int8_t protocol);
 222         __sum16         (*checksum_partial)(struct sk_buff *skb,
 223                                             unsigned int hook,
 224                                             unsigned int dataoff,
 225                                             unsigned int len,
 226                                             u_int8_t protocol);
 227         int             (*route)(struct net *net, struct dst_entry **dst,
 228                                  struct flowi *fl, bool strict);
 229         void            (*saveroute)(const struct sk_buff *skb,
 230                                      struct nf_queue_entry *entry);
 231         int             (*reroute)(struct sk_buff *skb,
 232                                    const struct nf_queue_entry *entry);
 233         int             route_key_size;
 234 };
 235
 236 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 237 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 238 {
 239         return rcu_dereference(nf_afinfo[family]);
 240 }
 241
 242 static inline __sum16
 243 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 244             u_int8_t protocol, unsigned short family)
 245 {
 246         const struct nf_afinfo *afinfo;
 247         __sum16 csum = 0;
 248
 249         rcu_read_lock();
 250         afinfo = nf_get_afinfo(family);
 251         if (afinfo)
 252                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 253         rcu_read_unlock();
 254         return csum;
 255 }
 256
 257 static inline __sum16
 258 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 259                     unsigned int dataoff, unsigned int len,
 260                     u_int8_t protocol, unsigned short family)
 261 {
 262         const struct nf_afinfo *afinfo;
 263         __sum16 csum = 0;
 264
 265         rcu_read_lock();
 266         afinfo = nf_get_afinfo(family);
 267         if (afinfo)
 268                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 269                                                 protocol);
 270         rcu_read_unlock();
 271         return csum;
 272 }
 273
 274 int nf_register_afinfo(const struct nf_afinfo *afinfo);
 275 void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 276
 277 #include <net/flow.h>
 278 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 279
 280 static inline void
 281 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 282 {
 283 #ifdef CONFIG_NF_NAT_NEEDED
 284         void (*decodefn)(struct sk_buff *, struct flowi *);
 285
 286         rcu_read_lock();
 287         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 288         if (decodefn)
 289                 decodefn(skb, fl);
 290         rcu_read_unlock();
 291 #endif
 292 }
 293
 294 #else /* !CONFIG_NETFILTER */
 295 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 296 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 297 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 298                                  struct sk_buff *skb,
 299                                  struct net_device *indev,
 300                                  struct net_device *outdev,
 301                                  int (*okfn)(struct sk_buff *), int thresh)
 302 {
 303         return okfn(skb);
 304 }
 305 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 306                           struct net_device *indev, struct net_device *outdev,
 307                           int (*okfn)(struct sk_buff *))
 308 {
 309         return 1;
 310 }
 311 struct flowi;
 312 static inline void
 313 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 314 {
 315 }
 316 #endif /*CONFIG_NETFILTER*/
 317
 318 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 319 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 320 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 321 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 322
 323 struct nf_conn;
 324 enum ip_conntrack_info;
 325 struct nlattr;
 326
 327 struct nfq_ct_hook {
 328         size_t (*build_size)(const struct nf_conn *ct);
 329         int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 330         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 331         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 332                              u32 portid, u32 report);
 333         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 334                            enum ip_conntrack_info ctinfo, s32 off);
 335 };
 336 extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 337 #else
 338 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 339 #endif
 340
 341 #endif /*__LINUX_NETFILTER_H*/