include/linux/netfilter.h

   1 #ifndef __LINUX_NETFILTER_H
   2 #define __LINUX_NETFILTER_H
   3
   4 #ifdef __KERNEL__
   5 #include <linux/init.h>
   6 #include <linux/skbuff.h>
   7 #include <linux/net.h>
   8 #include <linux/if.h>
   9 #include <linux/in.h>
  10 #include <linux/in6.h>
  11 #include <linux/wait.h>
  12 #include <linux/list.h>
  13 #endif
  14 #include <linux/types.h>
  15 #include <linux/compiler.h>
  16 #include <linux/sysctl.h>
  17
  18 /* Responses from hook functions. */
  19 #define NF_DROP 0
  20 #define NF_ACCEPT 1
  21 #define NF_STOLEN 2
  22 #define NF_QUEUE 3
  23 #define NF_REPEAT 4
  24 #define NF_STOP 5
  25 #define NF_MAX_VERDICT NF_STOP
  26
  27 /* we overload the higher bits for encoding auxiliary data such as the queue
  28  * number or errno values. Not nice, but better than additional function
  29  * arguments. */
  30 #define NF_VERDICT_MASK 0x000000ff
  31
  32 /* extra verdict flags have mask 0x0000ff00 */
  33 #define NF_VERDICT_FLAG_QUEUE_BYPASS    0x00008000
  34
  35 /* queue number (NF_QUEUE) or errno (NF_DROP) */
  36 #define NF_VERDICT_QMASK 0xffff0000
  37 #define NF_VERDICT_QBITS 16
  38
  39 #define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE)
  40
  41 #define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP)
  42
  43 /* only for userspace compatibility */
  44 #ifndef __KERNEL__
  45 /* Generic cache responses from hook functions.
  46    <= 0x2000 is used for protocol-flags. */
  47 #define NFC_UNKNOWN 0x4000
  48 #define NFC_ALTERED 0x8000
  49
  50 /* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */
  51 #define NF_VERDICT_BITS 16
  52 #endif
  53
  54 enum nf_inet_hooks {
  55         NF_INET_PRE_ROUTING,
  56         NF_INET_LOCAL_IN,
  57         NF_INET_FORWARD,
  58         NF_INET_LOCAL_OUT,
  59         NF_INET_POST_ROUTING,
  60         NF_INET_NUMHOOKS
  61 };
  62
  63 enum {
  64         NFPROTO_UNSPEC =  0,
  65         NFPROTO_IPV4   =  2,
  66         NFPROTO_ARP    =  3,
  67         NFPROTO_BRIDGE =  7,
  68         NFPROTO_IPV6   = 10,
  69         NFPROTO_DECNET = 12,
  70         NFPROTO_NUMPROTO,
  71 };
  72
  73 union nf_inet_addr {
  74         __u32           all[4];
  75         __be32          ip;
  76         __be32          ip6[4];
  77         struct in_addr  in;
  78         struct in6_addr in6;
  79 };
  80
  81 #ifdef __KERNEL__
  82 #ifdef CONFIG_NETFILTER
  83 static inline int NF_DROP_GETERR(int verdict)
  84 {
  85         return -(verdict >> NF_VERDICT_QBITS);
  86 }
  87
  88 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  89                                    const union nf_inet_addr *a2)
  90 {
  91         return a1->all[0] == a2->all[0] &&
  92                a1->all[1] == a2->all[1] &&
  93                a1->all[2] == a2->all[2] &&
  94                a1->all[3] == a2->all[3];
  95 }
  96
  97 extern void netfilter_init(void);
  98
  99 /* Largest hook number + 1 */
 100 #define NF_MAX_HOOKS 8
 101
 102 struct sk_buff;
 103
 104 typedef unsigned int nf_hookfn(unsigned int hooknum,
 105                                struct sk_buff *skb,
 106                                const struct net_device *in,
 107                                const struct net_device *out,
 108                                int (*okfn)(struct sk_buff *));
 109
 110 struct nf_hook_ops {
 111         struct list_head list;
 112
 113         /* User fills in from here down. */
 114         nf_hookfn *hook;
 115         struct module *owner;
 116         u_int8_t pf;
 117         unsigned int hooknum;
 118         /* Hooks are ordered in ascending priority. */
 119         int priority;
 120 };
 121
 122 struct nf_sockopt_ops {
 123         struct list_head list;
 124
 125         u_int8_t pf;
 126
 127         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 128         int set_optmin;
 129         int set_optmax;
 130         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 131 #ifdef CONFIG_COMPAT
 132         int (*compat_set)(struct sock *sk, int optval,
 133                         void __user *user, unsigned int len);
 134 #endif
 135         int get_optmin;
 136         int get_optmax;
 137         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 138 #ifdef CONFIG_COMPAT
 139         int (*compat_get)(struct sock *sk, int optval,
 140                         void __user *user, int *len);
 141 #endif
 142         /* Use the module struct to lock set/get code in place */
 143         struct module *owner;
 144 };
 145
 146 /* Function to register/unregister hook points. */
 147 int nf_register_hook(struct nf_hook_ops *reg);
 148 void nf_unregister_hook(struct nf_hook_ops *reg);
 149 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 150 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 151
 152 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 153    need to check permissions yourself! */
 154 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 155 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 156
 157 #ifdef CONFIG_SYSCTL
 158 /* Sysctl registration */
 159 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 160 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 161 #endif /* CONFIG_SYSCTL */
 162
 163 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 164
 165 #if defined(CONFIG_JUMP_LABEL)
 166 #include <linux/jump_label.h>
 167 extern struct jump_label_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 168 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 169 {
 170         if (__builtin_constant_p(pf) &&
 171             __builtin_constant_p(hook))
 172                 return static_branch(&nf_hooks_needed[pf][hook]);
 173
 174         return !list_empty(&nf_hooks[pf][hook]);
 175 }
 176 #else
 177 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 178 {
 179         return !list_empty(&nf_hooks[pf][hook]);
 180 }
 181 #endif
 182
 183 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 184                  struct net_device *indev, struct net_device *outdev,
 185                  int (*okfn)(struct sk_buff *), int thresh);
 186
 187 /**
 188  *      nf_hook_thresh - call a netfilter hook
 189  *
 190  *      Returns 1 if the hook has allowed the packet to pass.  The function
 191  *      okfn must be invoked by the caller in this case.  Any other return
 192  *      value indicates the packet has been consumed by the hook.
 193  */
 194 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 195                                  struct sk_buff *skb,
 196                                  struct net_device *indev,
 197                                  struct net_device *outdev,
 198                                  int (*okfn)(struct sk_buff *), int thresh)
 199 {
 200         if (nf_hooks_active(pf, hook))
 201                 return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 202         return 1;
 203 }
 204
 205 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 206                           struct net_device *indev, struct net_device *outdev,
 207                           int (*okfn)(struct sk_buff *))
 208 {
 209         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 210 }
 211
 212 /* Activate hook; either okfn or kfree_skb called, unless a hook
 213    returns NF_STOLEN (in which case, it's up to the hook to deal with
 214    the consequences).
 215
 216    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 217    accepted.
 218 */
 219
 220 /* RR:
 221    > I don't want nf_hook to return anything because people might forget
 222    > about async and trust the return value to mean "packet was ok".
 223
 224    AK:
 225    Just document it clearly, then you can expect some sense from kernel
 226    coders :)
 227 */
 228
 229 static inline int
 230 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 231                struct net_device *in, struct net_device *out,
 232                int (*okfn)(struct sk_buff *), int thresh)
 233 {
 234         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 235         if (ret == 1)
 236                 ret = okfn(skb);
 237         return ret;
 238 }
 239
 240 static inline int
 241 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 242              struct net_device *in, struct net_device *out,
 243              int (*okfn)(struct sk_buff *), bool cond)
 244 {
 245         int ret;
 246
 247         if (!cond ||
 248             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 249                 ret = okfn(skb);
 250         return ret;
 251 }
 252
 253 static inline int
 254 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 255         struct net_device *in, struct net_device *out,
 256         int (*okfn)(struct sk_buff *))
 257 {
 258         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 259 }
 260
 261 /* Call setsockopt() */
 262 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 263                   unsigned int len);
 264 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 265                   int *len);
 266 #ifdef CONFIG_COMPAT
 267 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 268                 char __user *opt, unsigned int len);
 269 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 270                 char __user *opt, int *len);
 271 #endif
 272
 273 /* Call this before modifying an existing packet: ensures it is
 274    modifiable and linear to the point you care about (writable_len).
 275    Returns true or false. */
 276 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 277
 278 struct flowi;
 279 struct nf_queue_entry;
 280
 281 struct nf_afinfo {
 282         unsigned short  family;
 283         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 284                                     unsigned int dataoff, u_int8_t protocol);
 285         __sum16         (*checksum_partial)(struct sk_buff *skb,
 286                                             unsigned int hook,
 287                                             unsigned int dataoff,
 288                                             unsigned int len,
 289                                             u_int8_t protocol);
 290         int             (*route)(struct net *net, struct dst_entry **dst,
 291                                  struct flowi *fl, bool strict);
 292         void            (*saveroute)(const struct sk_buff *skb,
 293                                      struct nf_queue_entry *entry);
 294         int             (*reroute)(struct sk_buff *skb,
 295                                    const struct nf_queue_entry *entry);
 296         int             route_key_size;
 297 };
 298
 299 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 300 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 301 {
 302         return rcu_dereference(nf_afinfo[family]);
 303 }
 304
 305 static inline __sum16
 306 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 307             u_int8_t protocol, unsigned short family)
 308 {
 309         const struct nf_afinfo *afinfo;
 310         __sum16 csum = 0;
 311
 312         rcu_read_lock();
 313         afinfo = nf_get_afinfo(family);
 314         if (afinfo)
 315                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 316         rcu_read_unlock();
 317         return csum;
 318 }
 319
 320 static inline __sum16
 321 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 322                     unsigned int dataoff, unsigned int len,
 323                     u_int8_t protocol, unsigned short family)
 324 {
 325         const struct nf_afinfo *afinfo;
 326         __sum16 csum = 0;
 327
 328         rcu_read_lock();
 329         afinfo = nf_get_afinfo(family);
 330         if (afinfo)
 331                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 332                                                 protocol);
 333         rcu_read_unlock();
 334         return csum;
 335 }
 336
 337 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 338 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 339
 340 #include <net/flow.h>
 341 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 342
 343 static inline void
 344 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 345 {
 346 #ifdef CONFIG_NF_NAT_NEEDED
 347         void (*decodefn)(struct sk_buff *, struct flowi *);
 348
 349         if (family == AF_INET) {
 350                 rcu_read_lock();
 351                 decodefn = rcu_dereference(ip_nat_decode_session);
 352                 if (decodefn)
 353                         decodefn(skb, fl);
 354                 rcu_read_unlock();
 355         }
 356 #endif
 357 }
 358
 359 #ifdef CONFIG_PROC_FS
 360 #include <linux/proc_fs.h>
 361 extern struct proc_dir_entry *proc_net_netfilter;
 362 #endif
 363
 364 #else /* !CONFIG_NETFILTER */
 365 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 366 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 367 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 368                                  struct sk_buff *skb,
 369                                  struct net_device *indev,
 370                                  struct net_device *outdev,
 371                                  int (*okfn)(struct sk_buff *), int thresh)
 372 {
 373         return okfn(skb);
 374 }
 375 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 376                           struct net_device *indev, struct net_device *outdev,
 377                           int (*okfn)(struct sk_buff *))
 378 {
 379         return 1;
 380 }
 381 struct flowi;
 382 static inline void
 383 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 384 {
 385 }
 386 #endif /*CONFIG_NETFILTER*/
 387
 388 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 389 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 390 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 391 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 392 #else
 393 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 394 #endif
 395
 396 #endif /*__KERNEL__*/
 397 #endif /*__LINUX_NETFILTER_H*/