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 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 166                  struct net_device *indev, struct net_device *outdev,
 167                  int (*okfn)(struct sk_buff *), int thresh);
 168
 169 /**
 170  *      nf_hook_thresh - call a netfilter hook
 171  *
 172  *      Returns 1 if the hook has allowed the packet to pass.  The function
 173  *      okfn must be invoked by the caller in this case.  Any other return
 174  *      value indicates the packet has been consumed by the hook.
 175  */
 176 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 177                                  struct sk_buff *skb,
 178                                  struct net_device *indev,
 179                                  struct net_device *outdev,
 180                                  int (*okfn)(struct sk_buff *), int thresh)
 181 {
 182 #ifndef CONFIG_NETFILTER_DEBUG
 183         if (list_empty(&nf_hooks[pf][hook]))
 184                 return 1;
 185 #endif
 186         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 187 }
 188
 189 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 190                           struct net_device *indev, struct net_device *outdev,
 191                           int (*okfn)(struct sk_buff *))
 192 {
 193         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 194 }
 195
 196 /* Activate hook; either okfn or kfree_skb called, unless a hook
 197    returns NF_STOLEN (in which case, it's up to the hook to deal with
 198    the consequences).
 199
 200    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 201    accepted.
 202 */
 203
 204 /* RR:
 205    > I don't want nf_hook to return anything because people might forget
 206    > about async and trust the return value to mean "packet was ok".
 207
 208    AK:
 209    Just document it clearly, then you can expect some sense from kernel
 210    coders :)
 211 */
 212
 213 static inline int
 214 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 215                struct net_device *in, struct net_device *out,
 216                int (*okfn)(struct sk_buff *), int thresh)
 217 {
 218         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 219         if (ret == 1)
 220                 ret = okfn(skb);
 221         return ret;
 222 }
 223
 224 static inline int
 225 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 226              struct net_device *in, struct net_device *out,
 227              int (*okfn)(struct sk_buff *), bool cond)
 228 {
 229         int ret;
 230
 231         if (!cond ||
 232             ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 233                 ret = okfn(skb);
 234         return ret;
 235 }
 236
 237 static inline int
 238 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 239         struct net_device *in, struct net_device *out,
 240         int (*okfn)(struct sk_buff *))
 241 {
 242         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 243 }
 244
 245 /* Call setsockopt() */
 246 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 247                   unsigned int len);
 248 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 249                   int *len);
 250 #ifdef CONFIG_COMPAT
 251 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 252                 char __user *opt, unsigned int len);
 253 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 254                 char __user *opt, int *len);
 255 #endif
 256
 257 /* Call this before modifying an existing packet: ensures it is
 258    modifiable and linear to the point you care about (writable_len).
 259    Returns true or false. */
 260 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 261
 262 struct flowi;
 263 struct nf_queue_entry;
 264
 265 struct nf_afinfo {
 266         unsigned short  family;
 267         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 268                                     unsigned int dataoff, u_int8_t protocol);
 269         __sum16         (*checksum_partial)(struct sk_buff *skb,
 270                                             unsigned int hook,
 271                                             unsigned int dataoff,
 272                                             unsigned int len,
 273                                             u_int8_t protocol);
 274         int             (*route)(struct net *net, struct dst_entry **dst,
 275                                  struct flowi *fl, bool strict);
 276         void            (*saveroute)(const struct sk_buff *skb,
 277                                      struct nf_queue_entry *entry);
 278         int             (*reroute)(struct sk_buff *skb,
 279                                    const struct nf_queue_entry *entry);
 280         int             route_key_size;
 281 };
 282
 283 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 284 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 285 {
 286         return rcu_dereference(nf_afinfo[family]);
 287 }
 288
 289 static inline __sum16
 290 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 291             u_int8_t protocol, unsigned short family)
 292 {
 293         const struct nf_afinfo *afinfo;
 294         __sum16 csum = 0;
 295
 296         rcu_read_lock();
 297         afinfo = nf_get_afinfo(family);
 298         if (afinfo)
 299                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 300         rcu_read_unlock();
 301         return csum;
 302 }
 303
 304 static inline __sum16
 305 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 306                     unsigned int dataoff, unsigned int len,
 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_partial(skb, hook, dataoff, len,
 316                                                 protocol);
 317         rcu_read_unlock();
 318         return csum;
 319 }
 320
 321 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 322 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 323
 324 #include <net/flow.h>
 325 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 326
 327 static inline void
 328 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 329 {
 330 #ifdef CONFIG_NF_NAT_NEEDED
 331         void (*decodefn)(struct sk_buff *, struct flowi *);
 332
 333         if (family == AF_INET) {
 334                 rcu_read_lock();
 335                 decodefn = rcu_dereference(ip_nat_decode_session);
 336                 if (decodefn)
 337                         decodefn(skb, fl);
 338                 rcu_read_unlock();
 339         }
 340 #endif
 341 }
 342
 343 #ifdef CONFIG_PROC_FS
 344 #include <linux/proc_fs.h>
 345 extern struct proc_dir_entry *proc_net_netfilter;
 346 #endif
 347
 348 #else /* !CONFIG_NETFILTER */
 349 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 350 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 351 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 352                                  struct sk_buff *skb,
 353                                  struct net_device *indev,
 354                                  struct net_device *outdev,
 355                                  int (*okfn)(struct sk_buff *), int thresh)
 356 {
 357         return okfn(skb);
 358 }
 359 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 360                           struct net_device *indev, struct net_device *outdev,
 361                           int (*okfn)(struct sk_buff *))
 362 {
 363         return 1;
 364 }
 365 struct flowi;
 366 static inline void
 367 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 368 {
 369 }
 370 #endif /*CONFIG_NETFILTER*/
 371
 372 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 373 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 374 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 375 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 376 #else
 377 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 378 #endif
 379
 380 #endif /*__KERNEL__*/
 381 #endif /*__LINUX_NETFILTER_H*/