linux/include/linux/netfilter.h
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   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
  97static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  98                                     union nf_inet_addr *result,
  99                                     const union nf_inet_addr *mask)
 100{
 101        result->all[0] = a1->all[0] & mask->all[0];
 102        result->all[1] = a1->all[1] & mask->all[1];
 103        result->all[2] = a1->all[2] & mask->all[2];
 104        result->all[3] = a1->all[3] & mask->all[3];
 105}
 106
 107extern void netfilter_init(void);
 108
 109/* Largest hook number + 1 */
 110#define NF_MAX_HOOKS 8
 111
 112struct sk_buff;
 113
 114typedef unsigned int nf_hookfn(unsigned int hooknum,
 115                               struct sk_buff *skb,
 116                               const struct net_device *in,
 117                               const struct net_device *out,
 118                               int (*okfn)(struct sk_buff *));
 119
 120struct nf_hook_ops {
 121        struct list_head list;
 122
 123        /* User fills in from here down. */
 124        nf_hookfn *hook;
 125        struct module *owner;
 126        u_int8_t pf;
 127        unsigned int hooknum;
 128        /* Hooks are ordered in ascending priority. */
 129        int priority;
 130};
 131
 132struct nf_sockopt_ops {
 133        struct list_head list;
 134
 135        u_int8_t pf;
 136
 137        /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 138        int set_optmin;
 139        int set_optmax;
 140        int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 141#ifdef CONFIG_COMPAT
 142        int (*compat_set)(struct sock *sk, int optval,
 143                        void __user *user, unsigned int len);
 144#endif
 145        int get_optmin;
 146        int get_optmax;
 147        int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 148#ifdef CONFIG_COMPAT
 149        int (*compat_get)(struct sock *sk, int optval,
 150                        void __user *user, int *len);
 151#endif
 152        /* Use the module struct to lock set/get code in place */
 153        struct module *owner;
 154};
 155
 156/* Function to register/unregister hook points. */
 157int nf_register_hook(struct nf_hook_ops *reg);
 158void nf_unregister_hook(struct nf_hook_ops *reg);
 159int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 160void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 161
 162/* Functions to register get/setsockopt ranges (non-inclusive).  You
 163   need to check permissions yourself! */
 164int nf_register_sockopt(struct nf_sockopt_ops *reg);
 165void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 166
 167extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 168
 169#if defined(CONFIG_JUMP_LABEL)
 170#include <linux/static_key.h>
 171extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 172static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 173{
 174        if (__builtin_constant_p(pf) &&
 175            __builtin_constant_p(hook))
 176                return static_key_false(&nf_hooks_needed[pf][hook]);
 177
 178        return !list_empty(&nf_hooks[pf][hook]);
 179}
 180#else
 181static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 182{
 183        return !list_empty(&nf_hooks[pf][hook]);
 184}
 185#endif
 186
 187int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 188                 struct net_device *indev, struct net_device *outdev,
 189                 int (*okfn)(struct sk_buff *), int thresh);
 190
 191/**
 192 *      nf_hook_thresh - call a netfilter hook
 193 *      
 194 *      Returns 1 if the hook has allowed the packet to pass.  The function
 195 *      okfn must be invoked by the caller in this case.  Any other return
 196 *      value indicates the packet has been consumed by the hook.
 197 */
 198static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 199                                 struct sk_buff *skb,
 200                                 struct net_device *indev,
 201                                 struct net_device *outdev,
 202                                 int (*okfn)(struct sk_buff *), int thresh)
 203{
 204        if (nf_hooks_active(pf, hook))
 205                return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 206        return 1;
 207}
 208
 209static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 210                          struct net_device *indev, struct net_device *outdev,
 211                          int (*okfn)(struct sk_buff *))
 212{
 213        return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 214}
 215                   
 216/* Activate hook; either okfn or kfree_skb called, unless a hook
 217   returns NF_STOLEN (in which case, it's up to the hook to deal with
 218   the consequences).
 219
 220   Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 221   accepted.
 222*/
 223
 224/* RR:
 225   > I don't want nf_hook to return anything because people might forget
 226   > about async and trust the return value to mean "packet was ok".
 227
 228   AK:
 229   Just document it clearly, then you can expect some sense from kernel
 230   coders :)
 231*/
 232
 233static inline int
 234NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 235               struct net_device *in, struct net_device *out,
 236               int (*okfn)(struct sk_buff *), int thresh)
 237{
 238        int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 239        if (ret == 1)
 240                ret = okfn(skb);
 241        return ret;
 242}
 243
 244static inline int
 245NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 246             struct net_device *in, struct net_device *out,
 247             int (*okfn)(struct sk_buff *), bool cond)
 248{
 249        int ret;
 250
 251        if (!cond ||
 252            ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 253                ret = okfn(skb);
 254        return ret;
 255}
 256
 257static inline int
 258NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 259        struct net_device *in, struct net_device *out,
 260        int (*okfn)(struct sk_buff *))
 261{
 262        return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 263}
 264
 265/* Call setsockopt() */
 266int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 267                  unsigned int len);
 268int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 269                  int *len);
 270#ifdef CONFIG_COMPAT
 271int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 272                char __user *opt, unsigned int len);
 273int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 274                char __user *opt, int *len);
 275#endif
 276
 277/* Call this before modifying an existing packet: ensures it is
 278   modifiable and linear to the point you care about (writable_len).
 279   Returns true or false. */
 280extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 281
 282struct flowi;
 283struct nf_queue_entry;
 284
 285struct nf_afinfo {
 286        unsigned short  family;
 287        __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 288                                    unsigned int dataoff, u_int8_t protocol);
 289        __sum16         (*checksum_partial)(struct sk_buff *skb,
 290                                            unsigned int hook,
 291                                            unsigned int dataoff,
 292                                            unsigned int len,
 293                                            u_int8_t protocol);
 294        int             (*route)(struct net *net, struct dst_entry **dst,
 295                                 struct flowi *fl, bool strict);
 296        void            (*saveroute)(const struct sk_buff *skb,
 297                                     struct nf_queue_entry *entry);
 298        int             (*reroute)(struct sk_buff *skb,
 299                                   const struct nf_queue_entry *entry);
 300        int             route_key_size;
 301};
 302
 303extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 304static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 305{
 306        return rcu_dereference(nf_afinfo[family]);
 307}
 308
 309static inline __sum16
 310nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 311            u_int8_t protocol, unsigned short family)
 312{
 313        const struct nf_afinfo *afinfo;
 314        __sum16 csum = 0;
 315
 316        rcu_read_lock();
 317        afinfo = nf_get_afinfo(family);
 318        if (afinfo)
 319                csum = afinfo->checksum(skb, hook, dataoff, protocol);
 320        rcu_read_unlock();
 321        return csum;
 322}
 323
 324static inline __sum16
 325nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 326                    unsigned int dataoff, unsigned int len,
 327                    u_int8_t protocol, unsigned short family)
 328{
 329        const struct nf_afinfo *afinfo;
 330        __sum16 csum = 0;
 331
 332        rcu_read_lock();
 333        afinfo = nf_get_afinfo(family);
 334        if (afinfo)
 335                csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 336                                                protocol);
 337        rcu_read_unlock();
 338        return csum;
 339}
 340
 341extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 342extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 343
 344#include <net/flow.h>
 345extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 346
 347static inline void
 348nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 349{
 350#ifdef CONFIG_NF_NAT_NEEDED
 351        void (*decodefn)(struct sk_buff *, struct flowi *);
 352
 353        if (family == AF_INET) {
 354                rcu_read_lock();
 355                decodefn = rcu_dereference(ip_nat_decode_session);
 356                if (decodefn)
 357                        decodefn(skb, fl);
 358                rcu_read_unlock();
 359        }
 360#endif
 361}
 362
 363#ifdef CONFIG_PROC_FS
 364#include <linux/proc_fs.h>
 365extern struct proc_dir_entry *proc_net_netfilter;
 366#endif
 367
 368#else /* !CONFIG_NETFILTER */
 369#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 370#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 371static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 372                                 struct sk_buff *skb,
 373                                 struct net_device *indev,
 374                                 struct net_device *outdev,
 375                                 int (*okfn)(struct sk_buff *), int thresh)
 376{
 377        return okfn(skb);
 378}
 379static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 380                          struct net_device *indev, struct net_device *outdev,
 381                          int (*okfn)(struct sk_buff *))
 382{
 383        return 1;
 384}
 385struct flowi;
 386static inline void
 387nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 388{
 389}
 390#endif /*CONFIG_NETFILTER*/
 391
 392#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 393extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 394extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 395extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 396
 397struct nf_conn;
 398struct nlattr;
 399
 400struct nfq_ct_hook {
 401        size_t (*build_size)(const struct nf_conn *ct);
 402        int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 403        int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 404};
 405extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 406
 407struct nfq_ct_nat_hook {
 408        void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 409                           u32 ctinfo, int off);
 410};
 411extern struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook;
 412#else
 413static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 414#endif
 415
 416#endif /*__KERNEL__*/
 417#endif /*__LINUX_NETFILTER_H*/
 418
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