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
  17 /* Responses from hook functions. */
  18 #define NF_DROP 0
  19 #define NF_ACCEPT 1
  20 #define NF_STOLEN 2
  21 #define NF_QUEUE 3
  22 #define NF_REPEAT 4
  23 #define NF_STOP 5
  24 #define NF_MAX_VERDICT NF_STOP
  25
  26 /* we overload the higher bits for encoding auxiliary data such as the queue
  27  * number. Not nice, but better than additional function arguments. */
  28 #define NF_VERDICT_MASK 0x0000ffff
  29 #define NF_VERDICT_BITS 16
  30
  31 #define NF_VERDICT_QMASK 0xffff0000
  32 #define NF_VERDICT_QBITS 16
  33
  34 #define NF_QUEUE_NR(x) ((((x) << NF_VERDICT_BITS) & NF_VERDICT_QMASK) | NF_QUEUE)
  35
  36 /* only for userspace compatibility */
  37 #ifndef __KERNEL__
  38 /* Generic cache responses from hook functions.
  39    <= 0x2000 is used for protocol-flags. */
  40 #define NFC_UNKNOWN 0x4000
  41 #define NFC_ALTERED 0x8000
  42 #endif
  43
  44 enum nf_inet_hooks {
  45         NF_INET_PRE_ROUTING,
  46         NF_INET_LOCAL_IN,
  47         NF_INET_FORWARD,
  48         NF_INET_LOCAL_OUT,
  49         NF_INET_POST_ROUTING,
  50         NF_INET_NUMHOOKS
  51 };
  52
  53 enum {
  54         NFPROTO_UNSPEC =  0,
  55         NFPROTO_IPV4   =  2,
  56         NFPROTO_ARP    =  3,
  57         NFPROTO_BRIDGE =  7,
  58         NFPROTO_IPV6   = 10,
  59         NFPROTO_DECNET = 12,
  60         NFPROTO_NUMPROTO,
  61 };
  62
  63 union nf_inet_addr {
  64         __u32           all[4];
  65         __be32          ip;
  66         __be32          ip6[4];
  67         struct in_addr  in;
  68         struct in6_addr in6;
  69 };
  70
  71 #ifdef __KERNEL__
  72 #ifdef CONFIG_NETFILTER
  73
  74 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  75                                    const union nf_inet_addr *a2)
  76 {
  77         return a1->all[0] == a2->all[0] &&
  78                a1->all[1] == a2->all[1] &&
  79                a1->all[2] == a2->all[2] &&
  80                a1->all[3] == a2->all[3];
  81 }
  82
  83 extern void netfilter_init(void);
  84
  85 /* Largest hook number + 1 */
  86 #define NF_MAX_HOOKS 8
  87
  88 struct sk_buff;
  89
  90 typedef unsigned int nf_hookfn(unsigned int hooknum,
  91                                struct sk_buff *skb,
  92                                const struct net_device *in,
  93                                const struct net_device *out,
  94                                int (*okfn)(struct sk_buff *));
  95
  96 struct nf_hook_ops {
  97         struct list_head list;
  98
  99         /* User fills in from here down. */
 100         nf_hookfn *hook;
 101         struct module *owner;
 102         u_int8_t pf;
 103         unsigned int hooknum;
 104         /* Hooks are ordered in ascending priority. */
 105         int priority;
 106 };
 107
 108 struct nf_sockopt_ops {
 109         struct list_head list;
 110
 111         u_int8_t pf;
 112
 113         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 114         int set_optmin;
 115         int set_optmax;
 116         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 117 #ifdef CONFIG_COMPAT
 118         int (*compat_set)(struct sock *sk, int optval,
 119                         void __user *user, unsigned int len);
 120 #endif
 121         int get_optmin;
 122         int get_optmax;
 123         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 124 #ifdef CONFIG_COMPAT
 125         int (*compat_get)(struct sock *sk, int optval,
 126                         void __user *user, int *len);
 127 #endif
 128         /* Use the module struct to lock set/get code in place */
 129         struct module *owner;
 130 };
 131
 132 /* Function to register/unregister hook points. */
 133 int nf_register_hook(struct nf_hook_ops *reg);
 134 void nf_unregister_hook(struct nf_hook_ops *reg);
 135 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 136 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 137
 138 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 139    need to check permissions yourself! */
 140 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 141 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 142
 143 #ifdef CONFIG_SYSCTL
 144 /* Sysctl registration */
 145 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 146 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 147 #endif /* CONFIG_SYSCTL */
 148
 149 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 150
 151 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 152                  struct net_device *indev, struct net_device *outdev,
 153                  int (*okfn)(struct sk_buff *), int thresh);
 154
 155 /**
 156  *      nf_hook_thresh - call a netfilter hook
 157  *
 158  *      Returns 1 if the hook has allowed the packet to pass.  The function
 159  *      okfn must be invoked by the caller in this case.  Any other return
 160  *      value indicates the packet has been consumed by the hook.
 161  */
 162 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 163                                  struct sk_buff *skb,
 164                                  struct net_device *indev,
 165                                  struct net_device *outdev,
 166                                  int (*okfn)(struct sk_buff *), int thresh)
 167 {
 168 #ifndef CONFIG_NETFILTER_DEBUG
 169         if (list_empty(&nf_hooks[pf][hook]))
 170                 return 1;
 171 #endif
 172         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 173 }
 174
 175 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 176                           struct net_device *indev, struct net_device *outdev,
 177                           int (*okfn)(struct sk_buff *))
 178 {
 179         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 180 }
 181
 182 /* Activate hook; either okfn or kfree_skb called, unless a hook
 183    returns NF_STOLEN (in which case, it's up to the hook to deal with
 184    the consequences).
 185
 186    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 187    accepted.
 188 */
 189
 190 /* RR:
 191    > I don't want nf_hook to return anything because people might forget
 192    > about async and trust the return value to mean "packet was ok".
 193
 194    AK:
 195    Just document it clearly, then you can expect some sense from kernel
 196    coders :)
 197 */
 198
 199 static inline int
 200 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 201                struct net_device *in, struct net_device *out,
 202                int (*okfn)(struct sk_buff *), int thresh)
 203 {
 204         int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 205         if (ret == 1)
 206                 ret = okfn(skb);
 207         return ret;
 208 }
 209
 210 static inline int
 211 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 212              struct net_device *in, struct net_device *out,
 213              int (*okfn)(struct sk_buff *), bool cond)
 214 {
 215         int ret;
 216
 217         if (!cond ||
 218             (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN) == 1))
 219                 ret = okfn(skb);
 220         return ret;
 221 }
 222
 223 static inline int
 224 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 225         struct net_device *in, struct net_device *out,
 226         int (*okfn)(struct sk_buff *))
 227 {
 228         return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 229 }
 230
 231 /* Call setsockopt() */
 232 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 233                   unsigned int len);
 234 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 235                   int *len);
 236 #ifdef CONFIG_COMPAT
 237 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 238                 char __user *opt, unsigned int len);
 239 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 240                 char __user *opt, int *len);
 241 #endif
 242
 243 /* Call this before modifying an existing packet: ensures it is
 244    modifiable and linear to the point you care about (writable_len).
 245    Returns true or false. */
 246 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 247
 248 struct flowi;
 249 struct nf_queue_entry;
 250
 251 struct nf_afinfo {
 252         unsigned short  family;
 253         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 254                                     unsigned int dataoff, u_int8_t protocol);
 255         __sum16         (*checksum_partial)(struct sk_buff *skb,
 256                                             unsigned int hook,
 257                                             unsigned int dataoff,
 258                                             unsigned int len,
 259                                             u_int8_t protocol);
 260         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 261         void            (*saveroute)(const struct sk_buff *skb,
 262                                      struct nf_queue_entry *entry);
 263         int             (*reroute)(struct sk_buff *skb,
 264                                    const struct nf_queue_entry *entry);
 265         int             route_key_size;
 266 };
 267
 268 extern const struct nf_afinfo *nf_afinfo[NFPROTO_NUMPROTO];
 269 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 270 {
 271         return rcu_dereference(nf_afinfo[family]);
 272 }
 273
 274 static inline __sum16
 275 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 276             u_int8_t protocol, unsigned short family)
 277 {
 278         const struct nf_afinfo *afinfo;
 279         __sum16 csum = 0;
 280
 281         rcu_read_lock();
 282         afinfo = nf_get_afinfo(family);
 283         if (afinfo)
 284                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 285         rcu_read_unlock();
 286         return csum;
 287 }
 288
 289 static inline __sum16
 290 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 291                     unsigned int dataoff, unsigned int len,
 292                     u_int8_t protocol, unsigned short family)
 293 {
 294         const struct nf_afinfo *afinfo;
 295         __sum16 csum = 0;
 296
 297         rcu_read_lock();
 298         afinfo = nf_get_afinfo(family);
 299         if (afinfo)
 300                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 301                                                 protocol);
 302         rcu_read_unlock();
 303         return csum;
 304 }
 305
 306 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 307 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 308
 309 #include <net/flow.h>
 310 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 311
 312 static inline void
 313 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 314 {
 315 #ifdef CONFIG_NF_NAT_NEEDED
 316         void (*decodefn)(struct sk_buff *, struct flowi *);
 317
 318         if (family == AF_INET) {
 319                 rcu_read_lock();
 320                 decodefn = rcu_dereference(ip_nat_decode_session);
 321                 if (decodefn)
 322                         decodefn(skb, fl);
 323                 rcu_read_unlock();
 324         }
 325 #endif
 326 }
 327
 328 #ifdef CONFIG_PROC_FS
 329 #include <linux/proc_fs.h>
 330 extern struct proc_dir_entry *proc_net_netfilter;
 331 #endif
 332
 333 #else /* !CONFIG_NETFILTER */
 334 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 335 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 336 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 337                                  struct sk_buff *skb,
 338                                  struct net_device *indev,
 339                                  struct net_device *outdev,
 340                                  int (*okfn)(struct sk_buff *), int thresh)
 341 {
 342         return okfn(skb);
 343 }
 344 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 345                           struct net_device *indev, struct net_device *outdev,
 346                           int (*okfn)(struct sk_buff *))
 347 {
 348         return 1;
 349 }
 350 struct flowi;
 351 static inline void
 352 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 353 {
 354 }
 355 #endif /*CONFIG_NETFILTER*/
 356
 357 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 358 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 359 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 360 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 361 #else
 362 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 363 #endif
 364
 365 #endif /*__KERNEL__*/
 366 #endif /*__LINUX_NETFILTER_H*/