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