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