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/types.h>
   7 #include <linux/skbuff.h>
   8 #include <linux/net.h>
   9 #include <linux/if.h>
  10 #include <linux/wait.h>
  11 #include <linux/list.h>
  12 #endif
  13 #include <linux/compiler.h>
  14
  15 /* Responses from hook functions. */
  16 #define NF_DROP 0
  17 #define NF_ACCEPT 1
  18 #define NF_STOLEN 2
  19 #define NF_QUEUE 3
  20 #define NF_REPEAT 4
  21 #define NF_MAX_VERDICT NF_REPEAT
  22
  23 /* Generic cache responses from hook functions.
  24    <= 0x2000 is used for protocol-flags. */
  25 #define NFC_UNKNOWN 0x4000
  26 #define NFC_ALTERED 0x8000
  27
  28 #ifdef __KERNEL__
  29 #include <linux/config.h>
  30 #ifdef CONFIG_NETFILTER
  31
  32 extern void netfilter_init(void);
  33
  34 /* Largest hook number + 1 */
  35 #define NF_MAX_HOOKS 8
  36
  37 struct sk_buff;
  38 struct net_device;
  39
  40 typedef unsigned int nf_hookfn(unsigned int hooknum,
  41                                struct sk_buff **skb,
  42                                const struct net_device *in,
  43                                const struct net_device *out,
  44                                int (*okfn)(struct sk_buff *));
  45
  46 struct nf_hook_ops
  47 {
  48         struct list_head list;
  49
  50         /* User fills in from here down. */
  51         nf_hookfn *hook;
  52         struct module *owner;
  53         int pf;
  54         int hooknum;
  55         /* Hooks are ordered in ascending priority. */
  56         int priority;
  57 };
  58
  59 struct nf_sockopt_ops
  60 {
  61         struct list_head list;
  62
  63         int pf;
  64
  65         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  66         int set_optmin;
  67         int set_optmax;
  68         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  69
  70         int get_optmin;
  71         int get_optmax;
  72         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  73
  74         /* Number of users inside set() or get(). */
  75         unsigned int use;
  76         struct task_struct *cleanup_task;
  77 };
  78
  79 /* Each queued (to userspace) skbuff has one of these. */
  80 struct nf_info
  81 {
  82         /* The ops struct which sent us to userspace. */
  83         struct nf_hook_ops *elem;
  84
  85         /* If we're sent to userspace, this keeps housekeeping info */
  86         int pf;
  87         unsigned int hook;
  88         struct net_device *indev, *outdev;
  89         int (*okfn)(struct sk_buff *);
  90 };
  91
  92 /* Function to register/unregister hook points. */
  93 int nf_register_hook(struct nf_hook_ops *reg);
  94 void nf_unregister_hook(struct nf_hook_ops *reg);
  95
  96 /* Functions to register get/setsockopt ranges (non-inclusive).  You
  97    need to check permissions yourself! */
  98 int nf_register_sockopt(struct nf_sockopt_ops *reg);
  99 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 100
 101 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 102
 103 typedef void nf_logfn(unsigned int hooknum,
 104                       const struct sk_buff *skb,
 105                       const struct net_device *in,
 106                       const struct net_device *out,
 107                       const char *prefix);
 108
 109 /* Function to register/unregister log function. */
 110 int nf_log_register(int pf, nf_logfn *logfn);
 111 void nf_log_unregister(int pf, nf_logfn *logfn);
 112
 113 /* Calls the registered backend logging function */
 114 void nf_log_packet(int pf,
 115                    unsigned int hooknum,
 116                    const struct sk_buff *skb,
 117                    const struct net_device *in,
 118                    const struct net_device *out,
 119                    const char *fmt, ...);
 120
 121 /* Activate hook; either okfn or kfree_skb called, unless a hook
 122    returns NF_STOLEN (in which case, it's up to the hook to deal with
 123    the consequences).
 124
 125    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 126    accepted.
 127 */
 128
 129 /* RR:
 130    > I don't want nf_hook to return anything because people might forget
 131    > about async and trust the return value to mean "packet was ok".
 132
 133    AK:
 134    Just document it clearly, then you can expect some sense from kernel
 135    coders :)
 136 */
 137
 138 /* This is gross, but inline doesn't cut it for avoiding the function
 139    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 140 #ifdef CONFIG_NETFILTER_DEBUG
 141 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                     \
 142  nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), INT_MIN)
 143 #define NF_HOOK_THRESH nf_hook_slow
 144 #else
 145 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                     \
 146 (list_empty(&nf_hooks[(pf)][(hook)])                                    \
 147  ? (okfn)(skb)                                                          \
 148  : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), INT_MIN))
 149 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)      \
 150 (list_empty(&nf_hooks[(pf)][(hook)])                                    \
 151  ? (okfn)(skb)                                                          \
 152  : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), (thresh)))
 153 #endif
 154
 155 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 156                  struct net_device *indev, struct net_device *outdev,
 157                  int (*okfn)(struct sk_buff *), int thresh);
 158
 159 /* Call setsockopt() */
 160 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 161                   int len);
 162 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 163                   int *len);
 164
 165 /* Packet queuing */
 166 typedef int (*nf_queue_outfn_t)(struct sk_buff *skb,
 167                                 struct nf_info *info, void *data);
 168 extern int nf_register_queue_handler(int pf,
 169                                      nf_queue_outfn_t outfn, void *data);
 170 extern int nf_unregister_queue_handler(int pf);
 171 extern void nf_reinject(struct sk_buff *skb,
 172                         struct nf_info *info,
 173                         unsigned int verdict);
 174
 175 extern inline struct ipt_target *
 176 ipt_find_target_lock(const char *name, int *error, struct semaphore *mutex);
 177 extern inline struct ip6t_target *
 178 ip6t_find_target_lock(const char *name, int *error, struct semaphore *mutex);
 179 extern inline struct arpt_target *
 180 arpt_find_target_lock(const char *name, int *error, struct semaphore *mutex);
 181 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 182
 183 #ifdef CONFIG_NETFILTER_DEBUG
 184 extern void nf_dump_skb(int pf, struct sk_buff *skb);
 185 #endif
 186
 187 /* FIXME: Before cache is ever used, this must be implemented for real. */
 188 extern void nf_invalidate_cache(int pf);
 189
 190 #else /* !CONFIG_NETFILTER */
 191 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 192 #endif /*CONFIG_NETFILTER*/
 193
 194 #endif /*__KERNEL__*/
 195 #endif /*__LINUX_NETFILTER_H*/