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 #define NFC_ALTERED 0x8000
  24 #define NFC_UNKNOWN 0x4000
  25
  26 #ifdef __KERNEL__
  27 #include <linux/config.h>
  28 #ifdef CONFIG_NETFILTER
  29
  30 extern void netfilter_init(void);
  31
  32 /* Largest hook number + 1 */
  33 #define NF_MAX_HOOKS 8
  34
  35 struct sk_buff;
  36 struct net_device;
  37
  38 typedef unsigned int nf_hookfn(unsigned int hooknum,
  39                                struct sk_buff **skb,
  40                                const struct net_device *in,
  41                                const struct net_device *out,
  42                                int (*okfn)(struct sk_buff *));
  43
  44 struct nf_hook_ops
  45 {
  46         struct list_head list;
  47
  48         /* User fills in from here down. */
  49         nf_hookfn *hook;
  50         int pf;
  51         int hooknum;
  52         /* Hooks are ordered in ascending priority. */
  53         int priority;
  54 };
  55
  56 struct nf_sockopt_ops
  57 {
  58         struct list_head list;
  59
  60         int pf;
  61
  62         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  63         int set_optmin;
  64         int set_optmax;
  65         int (*set)(struct sock *sk, int optval, void *user, unsigned int len);
  66
  67         int get_optmin;
  68         int get_optmax;
  69         int (*get)(struct sock *sk, int optval, void *user, int *len);
  70
  71         /* Number of users inside set() or get(). */
  72         unsigned int use;
  73         struct task_struct *cleanup_task;
  74 };
  75
  76 /* Each queued (to userspace) skbuff has one of these. */
  77 struct nf_info
  78 {
  79         /* The ops struct which sent us to userspace. */
  80         struct nf_hook_ops *elem;
  81
  82         /* If we're sent to userspace, this keeps housekeeping info */
  83         int pf;
  84         unsigned int hook;
  85         struct net_device *indev, *outdev;
  86         int (*okfn)(struct sk_buff *);
  87 };
  88
  89 /* Function to register/unregister hook points. */
  90 int nf_register_hook(struct nf_hook_ops *reg);
  91 void nf_unregister_hook(struct nf_hook_ops *reg);
  92
  93 /* Functions to register get/setsockopt ranges (non-inclusive).  You
  94    need to check permissions yourself! */
  95 int nf_register_sockopt(struct nf_sockopt_ops *reg);
  96 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
  97
  98 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
  99
 100 /* Activate hook; either okfn or kfree_skb called, unless a hook
 101    returns NF_STOLEN (in which case, it's up to the hook to deal with
 102    the consequences).
 103
 104    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 105    accepted.
 106 */
 107
 108 /* RR:
 109    > I don't want nf_hook to return anything because people might forget
 110    > about async and trust the return value to mean "packet was ok".
 111
 112    AK:
 113    Just document it clearly, then you can expect some sense from kernel
 114    coders :)
 115 */
 116
 117 /* This is gross, but inline doesn't cut it for avoiding the function
 118    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 119 #ifdef CONFIG_NETFILTER_DEBUG
 120 #define NF_HOOK nf_hook_slow
 121 #else
 122 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                     \
 123 (list_empty(&nf_hooks[(pf)][(hook)])                                    \
 124  ? (okfn)(skb)                                                          \
 125  : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn)))
 126 #endif
 127
 128 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 129                  struct net_device *indev, struct net_device *outdev,
 130                  int (*okfn)(struct sk_buff *));
 131
 132 /* Call setsockopt() */
 133 int nf_setsockopt(struct sock *sk, int pf, int optval, char *opt,
 134                   int len);
 135 int nf_getsockopt(struct sock *sk, int pf, int optval, char *opt,
 136                   int *len);
 137
 138 /* Packet queuing */
 139 typedef int (*nf_queue_outfn_t)(struct sk_buff *skb,
 140                                 struct nf_info *info, void *data);
 141 extern int nf_register_queue_handler(int pf,
 142                                      nf_queue_outfn_t outfn, void *data);
 143 extern int nf_unregister_queue_handler(int pf);
 144 extern void nf_reinject(struct sk_buff *skb,
 145                         struct nf_info *info,
 146                         unsigned int verdict);
 147
 148 #ifdef CONFIG_NETFILTER_DEBUG
 149 extern void nf_dump_skb(int pf, struct sk_buff *skb);
 150 #endif
 151
 152 /* FIXME: Before cache is ever used, this must be implemented for real. */
 153 extern void nf_invalidate_cache(int pf);
 154
 155 #else /* !CONFIG_NETFILTER */
 156 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 157 #endif /*CONFIG_NETFILTER*/
 158
 159 /* From arch/i386/kernel/smp.c:
 160  *
 161  *      Why isn't this somewhere standard ??
 162  *
 163  * Maybe because this procedure is horribly buggy, and does
 164  * not deserve to live.  Think about signedness issues for five
 165  * seconds to see why.          - Linus
 166  */
 167
 168 /* Two signed, return a signed. */
 169 #define SMAX(a,b) ((ssize_t)(a)>(ssize_t)(b) ? (ssize_t)(a) : (ssize_t)(b))
 170 #define SMIN(a,b) ((ssize_t)(a)<(ssize_t)(b) ? (ssize_t)(a) : (ssize_t)(b))
 171
 172 /* Two unsigned, return an unsigned. */
 173 #define UMAX(a,b) ((size_t)(a)>(size_t)(b) ? (size_t)(a) : (size_t)(b))
 174 #define UMIN(a,b) ((size_t)(a)<(size_t)(b) ? (size_t)(a) : (size_t)(b))
 175
 176 /* Two unsigned, return a signed. */
 177 #define SUMAX(a,b) ((size_t)(a)>(size_t)(b) ? (ssize_t)(a) : (ssize_t)(b))
 178 #define SUMIN(a,b) ((size_t)(a)<(size_t)(b) ? (ssize_t)(a) : (ssize_t)(b))
 179 #endif /*__KERNEL__*/
 180
 181 #endif /*__LINUX_NETFILTER_H*/