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_STOP 5
  22 #define NF_MAX_VERDICT NF_STOP
  23
  24 /* Generic cache responses from hook functions.
  25    <= 0x2000 is used for protocol-flags. */
  26 #define NFC_UNKNOWN 0x4000
  27 #define NFC_ALTERED 0x8000
  28
  29 #ifdef __KERNEL__
  30 #include <linux/config.h>
  31 #ifdef CONFIG_NETFILTER
  32
  33 extern void netfilter_init(void);
  34
  35 /* Largest hook number + 1 */
  36 #define NF_MAX_HOOKS 8
  37
  38 struct sk_buff;
  39 struct net_device;
  40
  41 typedef unsigned int nf_hookfn(unsigned int hooknum,
  42                                struct sk_buff **skb,
  43                                const struct net_device *in,
  44                                const struct net_device *out,
  45                                int (*okfn)(struct sk_buff *));
  46
  47 struct nf_hook_ops
  48 {
  49         struct list_head list;
  50
  51         /* User fills in from here down. */
  52         nf_hookfn *hook;
  53         struct module *owner;
  54         int pf;
  55         int hooknum;
  56         /* Hooks are ordered in ascending priority. */
  57         int priority;
  58 };
  59
  60 struct nf_sockopt_ops
  61 {
  62         struct list_head list;
  63
  64         int pf;
  65
  66         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  67         int set_optmin;
  68         int set_optmax;
  69         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  70
  71         int get_optmin;
  72         int get_optmax;
  73         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  74
  75         /* Number of users inside set() or get(). */
  76         unsigned int use;
  77         struct task_struct *cleanup_task;
  78 };
  79
  80 /* Each queued (to userspace) skbuff has one of these. */
  81 struct nf_info
  82 {
  83         /* The ops struct which sent us to userspace. */
  84         struct nf_hook_ops *elem;
  85
  86         /* If we're sent to userspace, this keeps housekeeping info */
  87         int pf;
  88         unsigned int hook;
  89         struct net_device *indev, *outdev;
  90         int (*okfn)(struct sk_buff *);
  91 };
  92
  93 /* Function to register/unregister hook points. */
  94 int nf_register_hook(struct nf_hook_ops *reg);
  95 void nf_unregister_hook(struct nf_hook_ops *reg);
  96
  97 /* Functions to register get/setsockopt ranges (non-inclusive).  You
  98    need to check permissions yourself! */
  99 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 100 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 101
 102 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 103
 104 typedef void nf_logfn(unsigned int hooknum,
 105                       const struct sk_buff *skb,
 106                       const struct net_device *in,
 107                       const struct net_device *out,
 108                       const char *prefix);
 109
 110 /* Function to register/unregister log function. */
 111 int nf_log_register(int pf, nf_logfn *logfn);
 112 void nf_log_unregister(int pf, nf_logfn *logfn);
 113
 114 /* Calls the registered backend logging function */
 115 void nf_log_packet(int pf,
 116                    unsigned int hooknum,
 117                    const struct sk_buff *skb,
 118                    const struct net_device *in,
 119                    const struct net_device *out,
 120                    const char *fmt, ...);
 121
 122 /* Activate hook; either okfn or kfree_skb called, unless a hook
 123    returns NF_STOLEN (in which case, it's up to the hook to deal with
 124    the consequences).
 125
 126    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 127    accepted.
 128 */
 129
 130 /* RR:
 131    > I don't want nf_hook to return anything because people might forget
 132    > about async and trust the return value to mean "packet was ok".
 133
 134    AK:
 135    Just document it clearly, then you can expect some sense from kernel
 136    coders :)
 137 */
 138
 139 /* This is gross, but inline doesn't cut it for avoiding the function
 140    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 141 #ifdef CONFIG_NETFILTER_DEBUG
 142 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                            \
 143 ({int __ret;                                                                   \
 144 if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
 145         __ret = (okfn)(skb);                                                   \
 146 __ret;})
 147 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 148 ({int __ret;                                                                   \
 149 if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1)  \
 150         __ret = (okfn)(skb);                                                   \
 151 __ret;})
 152 #else
 153 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                            \
 154 ({int __ret;                                                                   \
 155 if (list_empty(&nf_hooks[pf][hook]) ||                                         \
 156     (__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
 157         __ret = (okfn)(skb);                                                   \
 158 __ret;})
 159 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 160 ({int __ret;                                                                   \
 161 if (list_empty(&nf_hooks[pf][hook]) ||                                         \
 162     (__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1)  \
 163         __ret = (okfn)(skb);                                                   \
 164 __ret;})
 165 #endif
 166
 167 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
 168                  struct net_device *indev, struct net_device *outdev,
 169                  int (*okfn)(struct sk_buff *), int thresh);
 170
 171 /* Call setsockopt() */
 172 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 173                   int len);
 174 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 175                   int *len);
 176
 177 /* Packet queuing */
 178 typedef int (*nf_queue_outfn_t)(struct sk_buff *skb,
 179                                 struct nf_info *info, void *data);
 180 extern int nf_register_queue_handler(int pf,
 181                                      nf_queue_outfn_t outfn, void *data);
 182 extern int nf_unregister_queue_handler(int pf);
 183 extern void nf_reinject(struct sk_buff *skb,
 184                         struct nf_info *info,
 185                         unsigned int verdict);
 186
 187 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 188 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 189
 190 /* FIXME: Before cache is ever used, this must be implemented for real. */
 191 extern void nf_invalidate_cache(int pf);
 192
 193 #else /* !CONFIG_NETFILTER */
 194 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 195 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 196 #endif /*CONFIG_NETFILTER*/
 197
 198 #endif /*__KERNEL__*/
 199 #endif /*__LINUX_NETFILTER_H*/