LXR linux/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
  54enum 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
  63enum {
  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
  73union 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
  83static inline int NF_DROP_GETERR(int verdict)
  84{
  85        return -(verdict >> NF_VERDICT_QBITS);
  86}
  87
  88static 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
  97extern void netfilter_init(void);
  98
  99/* Largest hook number + 1 */
 100#define NF_MAX_HOOKS 8
 101
 102struct sk_buff;
 103
 104typedef 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
 110struct 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
 122struct 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. */
 147int nf_register_hook(struct nf_hook_ops *reg);
 148void nf_unregister_hook(struct nf_hook_ops *reg);
 149int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 150void 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! */
 154int nf_register_sockopt(struct nf_sockopt_ops *reg);
 155void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 156
 157extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 158
 159#if defined(CONFIG_JUMP_LABEL)
 160#include <linux/static_key.h>
 161extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 162static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 163{
 164        if (__builtin_constant_p(pf) &&
 165            __builtin_constant_p(hook))
 166                return static_key_false(&nf_hooks_needed[pf][hook]);
 167
 168        return !list_empty(&nf_hooks[pf][hook]);
 169}
 170#else
 171static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 172{
 173        return !list_empty(&nf_hooks[pf][hook]);
 174}
 175#endif
 176
 177int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 178                 struct net_device *indev, struct net_device *outdev,
 179                 int (*okfn)(struct sk_buff *), int thresh);
 180
 181/**
 182 *      nf_hook_thresh - call a netfilter hook
 183 *      
 184 *      Returns 1 if the hook has allowed the packet to pass.  The function
 185 *      okfn must be invoked by the caller in this case.  Any other return
 186 *      value indicates the packet has been consumed by the hook.
 187 */
 188static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 189                                 struct sk_buff *skb,
 190                                 struct net_device *indev,
 191                                 struct net_device *outdev,
 192                                 int (*okfn)(struct sk_buff *), int thresh)
 193{
 194        if (nf_hooks_active(pf, hook))
 195                return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 196        return 1;
 197}
 198
 199static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 200                          struct net_device *indev, struct net_device *outdev,
 201                          int (*okfn)(struct sk_buff *))
 202{
 203        return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 204}
 205                   
 206/* Activate hook; either okfn or kfree_skb called, unless a hook
 207   returns NF_STOLEN (in which case, it's up to the hook to deal with
 208   the consequences).
 209
 210   Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 211   accepted.
 212*/
 213
 214/* RR:
 215   > I don't want nf_hook to return anything because people might forget
 216   > about async and trust the return value to mean "packet was ok".
 217
 218   AK:
 219   Just document it clearly, then you can expect some sense from kernel
 220   coders :)
 221*/
 222
 223static inline int
 224NF_HOOK_THRESH(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 *), int thresh)
 227{
 228        int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 229        if (ret == 1)
 230                ret = okfn(skb);
 231        return ret;
 232}
 233
 234static inline int
 235NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 236             struct net_device *in, struct net_device *out,
 237             int (*okfn)(struct sk_buff *), bool cond)
 238{
 239        int ret;
 240
 241        if (!cond ||
 242            ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 243                ret = okfn(skb);
 244        return ret;
 245}
 246
 247static inline int
 248NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 249        struct net_device *in, struct net_device *out,
 250        int (*okfn)(struct sk_buff *))
 251{
 252        return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 253}
 254
 255/* Call setsockopt() */
 256int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 257                  unsigned int len);
 258int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 259                  int *len);
 260#ifdef CONFIG_COMPAT
 261int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 262                char __user *opt, unsigned int len);
 263int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 264                char __user *opt, int *len);
 265#endif
 266
 267/* Call this before modifying an existing packet: ensures it is
 268   modifiable and linear to the point you care about (writable_len).
 269   Returns true or false. */
 270extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 271
 272struct flowi;
 273struct nf_queue_entry;
 274
 275struct nf_afinfo {
 276        unsigned short  family;
 277        __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 278                                    unsigned int dataoff, u_int8_t protocol);
 279        __sum16         (*checksum_partial)(struct sk_buff *skb,
 280                                            unsigned int hook,
 281                                            unsigned int dataoff,
 282                                            unsigned int len,
 283                                            u_int8_t protocol);
 284        int             (*route)(struct net *net, struct dst_entry **dst,
 285                                 struct flowi *fl, bool strict);
 286        void            (*saveroute)(const struct sk_buff *skb,
 287                                     struct nf_queue_entry *entry);
 288        int             (*reroute)(struct sk_buff *skb,
 289                                   const struct nf_queue_entry *entry);
 290        int             route_key_size;
 291};
 292
 293extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 294static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 295{
 296        return rcu_dereference(nf_afinfo[family]);
 297}
 298
 299static inline __sum16
 300nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 301            u_int8_t protocol, unsigned short family)
 302{
 303        const struct nf_afinfo *afinfo;
 304        __sum16 csum = 0;
 305
 306        rcu_read_lock();
 307        afinfo = nf_get_afinfo(family);
 308        if (afinfo)
 309                csum = afinfo->checksum(skb, hook, dataoff, protocol);
 310        rcu_read_unlock();
 311        return csum;
 312}
 313
 314static inline __sum16
 315nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 316                    unsigned int dataoff, unsigned int len,
 317                    u_int8_t protocol, unsigned short family)
 318{
 319        const struct nf_afinfo *afinfo;
 320        __sum16 csum = 0;
 321
 322        rcu_read_lock();
 323        afinfo = nf_get_afinfo(family);
 324        if (afinfo)
 325                csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 326                                                protocol);
 327        rcu_read_unlock();
 328        return csum;
 329}
 330
 331extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 332extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 333
 334#include <net/flow.h>
 335extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 336
 337static inline void
 338nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 339{
 340#ifdef CONFIG_NF_NAT_NEEDED
 341        void (*decodefn)(struct sk_buff *, struct flowi *);
 342
 343        if (family == AF_INET) {
 344                rcu_read_lock();
 345                decodefn = rcu_dereference(ip_nat_decode_session);
 346                if (decodefn)
 347                        decodefn(skb, fl);
 348                rcu_read_unlock();
 349        }
 350#endif
 351}
 352
 353#ifdef CONFIG_PROC_FS
 354#include <linux/proc_fs.h>
 355extern struct proc_dir_entry *proc_net_netfilter;
 356#endif
 357
 358#else /* !CONFIG_NETFILTER */
 359#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 360#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 361static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 362                                 struct sk_buff *skb,
 363                                 struct net_device *indev,
 364                                 struct net_device *outdev,
 365                                 int (*okfn)(struct sk_buff *), int thresh)
 366{
 367        return okfn(skb);
 368}
 369static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 370                          struct net_device *indev, struct net_device *outdev,
 371                          int (*okfn)(struct sk_buff *))
 372{
 373        return 1;
 374}
 375struct flowi;
 376static inline void
 377nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 378{
 379}
 380#endif /*CONFIG_NETFILTER*/
 381
 382#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 383extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 384extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 385extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 386#else
 387static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 388#endif
 389
 390#endif /*__KERNEL__*/
 391#endif /*__LINUX_NETFILTER_H*/
 392