linux/include/linux/netfilter.h
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   1#ifndef __LINUX_NETFILTER_H
   2#define __LINUX_NETFILTER_H
   3
   4#include <linux/init.h>
   5#include <linux/skbuff.h>
   6#include <linux/net.h>
   7#include <linux/if.h>
   8#include <linux/in.h>
   9#include <linux/in6.h>
  10#include <linux/wait.h>
  11#include <linux/list.h>
  12#include <uapi/linux/netfilter.h>
  13#ifdef CONFIG_NETFILTER
  14static inline int NF_DROP_GETERR(int verdict)
  15{
  16        return -(verdict >> NF_VERDICT_QBITS);
  17}
  18
  19static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  20                                   const union nf_inet_addr *a2)
  21{
  22        return a1->all[0] == a2->all[0] &&
  23               a1->all[1] == a2->all[1] &&
  24               a1->all[2] == a2->all[2] &&
  25               a1->all[3] == a2->all[3];
  26}
  27
  28static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  29                                     union nf_inet_addr *result,
  30                                     const union nf_inet_addr *mask)
  31{
  32        result->all[0] = a1->all[0] & mask->all[0];
  33        result->all[1] = a1->all[1] & mask->all[1];
  34        result->all[2] = a1->all[2] & mask->all[2];
  35        result->all[3] = a1->all[3] & mask->all[3];
  36}
  37
  38extern void netfilter_init(void);
  39
  40/* Largest hook number + 1 */
  41#define NF_MAX_HOOKS 8
  42
  43struct sk_buff;
  44
  45typedef unsigned int nf_hookfn(unsigned int hooknum,
  46                               struct sk_buff *skb,
  47                               const struct net_device *in,
  48                               const struct net_device *out,
  49                               int (*okfn)(struct sk_buff *));
  50
  51struct nf_hook_ops {
  52        struct list_head list;
  53
  54        /* User fills in from here down. */
  55        nf_hookfn *hook;
  56        struct module *owner;
  57        u_int8_t pf;
  58        unsigned int hooknum;
  59        /* Hooks are ordered in ascending priority. */
  60        int priority;
  61};
  62
  63struct nf_sockopt_ops {
  64        struct list_head list;
  65
  66        u_int8_t pf;
  67
  68        /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  69        int set_optmin;
  70        int set_optmax;
  71        int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  72#ifdef CONFIG_COMPAT
  73        int (*compat_set)(struct sock *sk, int optval,
  74                        void __user *user, unsigned int len);
  75#endif
  76        int get_optmin;
  77        int get_optmax;
  78        int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  79#ifdef CONFIG_COMPAT
  80        int (*compat_get)(struct sock *sk, int optval,
  81                        void __user *user, int *len);
  82#endif
  83        /* Use the module struct to lock set/get code in place */
  84        struct module *owner;
  85};
  86
  87/* Function to register/unregister hook points. */
  88int nf_register_hook(struct nf_hook_ops *reg);
  89void nf_unregister_hook(struct nf_hook_ops *reg);
  90int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
  91void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
  92
  93/* Functions to register get/setsockopt ranges (non-inclusive).  You
  94   need to check permissions yourself! */
  95int nf_register_sockopt(struct nf_sockopt_ops *reg);
  96void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
  97
  98extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
  99
 100#if defined(CONFIG_JUMP_LABEL)
 101#include <linux/static_key.h>
 102extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 103static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 104{
 105        if (__builtin_constant_p(pf) &&
 106            __builtin_constant_p(hook))
 107                return static_key_false(&nf_hooks_needed[pf][hook]);
 108
 109        return !list_empty(&nf_hooks[pf][hook]);
 110}
 111#else
 112static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 113{
 114        return !list_empty(&nf_hooks[pf][hook]);
 115}
 116#endif
 117
 118int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 119                 struct net_device *indev, struct net_device *outdev,
 120                 int (*okfn)(struct sk_buff *), int thresh);
 121
 122/**
 123 *      nf_hook_thresh - call a netfilter hook
 124 *      
 125 *      Returns 1 if the hook has allowed the packet to pass.  The function
 126 *      okfn must be invoked by the caller in this case.  Any other return
 127 *      value indicates the packet has been consumed by the hook.
 128 */
 129static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 130                                 struct sk_buff *skb,
 131                                 struct net_device *indev,
 132                                 struct net_device *outdev,
 133                                 int (*okfn)(struct sk_buff *), int thresh)
 134{
 135        if (nf_hooks_active(pf, hook))
 136                return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 137        return 1;
 138}
 139
 140static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 141                          struct net_device *indev, struct net_device *outdev,
 142                          int (*okfn)(struct sk_buff *))
 143{
 144        return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 145}
 146                   
 147/* Activate hook; either okfn or kfree_skb called, unless a hook
 148   returns NF_STOLEN (in which case, it's up to the hook to deal with
 149   the consequences).
 150
 151   Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 152   accepted.
 153*/
 154
 155/* RR:
 156   > I don't want nf_hook to return anything because people might forget
 157   > about async and trust the return value to mean "packet was ok".
 158
 159   AK:
 160   Just document it clearly, then you can expect some sense from kernel
 161   coders :)
 162*/
 163
 164static inline int
 165NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 166               struct net_device *in, struct net_device *out,
 167               int (*okfn)(struct sk_buff *), int thresh)
 168{
 169        int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 170        if (ret == 1)
 171                ret = okfn(skb);
 172        return ret;
 173}
 174
 175static inline int
 176NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 177             struct net_device *in, struct net_device *out,
 178             int (*okfn)(struct sk_buff *), bool cond)
 179{
 180        int ret;
 181
 182        if (!cond ||
 183            ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 184                ret = okfn(skb);
 185        return ret;
 186}
 187
 188static inline int
 189NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 190        struct net_device *in, struct net_device *out,
 191        int (*okfn)(struct sk_buff *))
 192{
 193        return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 194}
 195
 196/* Call setsockopt() */
 197int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 198                  unsigned int len);
 199int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 200                  int *len);
 201#ifdef CONFIG_COMPAT
 202int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 203                char __user *opt, unsigned int len);
 204int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 205                char __user *opt, int *len);
 206#endif
 207
 208/* Call this before modifying an existing packet: ensures it is
 209   modifiable and linear to the point you care about (writable_len).
 210   Returns true or false. */
 211extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 212
 213struct flowi;
 214struct nf_queue_entry;
 215
 216struct nf_afinfo {
 217        unsigned short  family;
 218        __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 219                                    unsigned int dataoff, u_int8_t protocol);
 220        __sum16         (*checksum_partial)(struct sk_buff *skb,
 221                                            unsigned int hook,
 222                                            unsigned int dataoff,
 223                                            unsigned int len,
 224                                            u_int8_t protocol);
 225        int             (*route)(struct net *net, struct dst_entry **dst,
 226                                 struct flowi *fl, bool strict);
 227        void            (*saveroute)(const struct sk_buff *skb,
 228                                     struct nf_queue_entry *entry);
 229        int             (*reroute)(struct sk_buff *skb,
 230                                   const struct nf_queue_entry *entry);
 231        int             route_key_size;
 232};
 233
 234extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 235static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 236{
 237        return rcu_dereference(nf_afinfo[family]);
 238}
 239
 240static inline __sum16
 241nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 242            u_int8_t protocol, unsigned short family)
 243{
 244        const struct nf_afinfo *afinfo;
 245        __sum16 csum = 0;
 246
 247        rcu_read_lock();
 248        afinfo = nf_get_afinfo(family);
 249        if (afinfo)
 250                csum = afinfo->checksum(skb, hook, dataoff, protocol);
 251        rcu_read_unlock();
 252        return csum;
 253}
 254
 255static inline __sum16
 256nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 257                    unsigned int dataoff, unsigned int len,
 258                    u_int8_t protocol, unsigned short family)
 259{
 260        const struct nf_afinfo *afinfo;
 261        __sum16 csum = 0;
 262
 263        rcu_read_lock();
 264        afinfo = nf_get_afinfo(family);
 265        if (afinfo)
 266                csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 267                                                protocol);
 268        rcu_read_unlock();
 269        return csum;
 270}
 271
 272extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 273extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 274
 275#include <net/flow.h>
 276extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 277
 278static inline void
 279nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 280{
 281#ifdef CONFIG_NF_NAT_NEEDED
 282        void (*decodefn)(struct sk_buff *, struct flowi *);
 283
 284        rcu_read_lock();
 285        decodefn = rcu_dereference(nf_nat_decode_session_hook);
 286        if (decodefn)
 287                decodefn(skb, fl);
 288        rcu_read_unlock();
 289#endif
 290}
 291
 292#ifdef CONFIG_PROC_FS
 293#include <linux/proc_fs.h>
 294extern struct proc_dir_entry *proc_net_netfilter;
 295#endif
 296
 297#else /* !CONFIG_NETFILTER */
 298#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 299#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 300static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 301                                 struct sk_buff *skb,
 302                                 struct net_device *indev,
 303                                 struct net_device *outdev,
 304                                 int (*okfn)(struct sk_buff *), int thresh)
 305{
 306        return okfn(skb);
 307}
 308static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 309                          struct net_device *indev, struct net_device *outdev,
 310                          int (*okfn)(struct sk_buff *))
 311{
 312        return 1;
 313}
 314struct flowi;
 315static inline void
 316nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 317{
 318}
 319#endif /*CONFIG_NETFILTER*/
 320
 321#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 322extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 323extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 324extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 325
 326struct nf_conn;
 327struct nlattr;
 328
 329struct nfq_ct_hook {
 330        size_t (*build_size)(const struct nf_conn *ct);
 331        int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 332        int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 333};
 334extern struct nfq_ct_hook __rcu *nfq_ct_hook;
 335
 336struct nfq_ct_nat_hook {
 337        void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 338                           u32 ctinfo, int off);
 339};
 340extern struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook;
 341#else
 342static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 343#endif
 344
 345#endif /*__LINUX_NETFILTER_H*/
 346
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