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