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 /* we overload the higher bits for encoding auxiliary data such as the queue
  25  * number. Not nice, but better than additional function arguments. */
  26 #define NF_VERDICT_MASK 0x0000ffff
  27 #define NF_VERDICT_BITS 16
  28
  29 #define NF_VERDICT_QMASK 0xffff0000
  30 #define NF_VERDICT_QBITS 16
  31
  32 #define NF_QUEUE_NR(x) ((x << NF_VERDICT_QBITS) & NF_VERDICT_QMASK || NF_QUEUE)
  33
  34 /* only for userspace compatibility */
  35 #ifndef __KERNEL__
  36 /* Generic cache responses from hook functions.
  37    <= 0x2000 is used for protocol-flags. */
  38 #define NFC_UNKNOWN 0x4000
  39 #define NFC_ALTERED 0x8000
  40 #endif
  41
  42 #ifdef __KERNEL__
  43 #include <linux/config.h>
  44 #ifdef CONFIG_NETFILTER
  45
  46 extern void netfilter_init(void);
  47
  48 /* Largest hook number + 1 */
  49 #define NF_MAX_HOOKS 8
  50
  51 struct sk_buff;
  52 struct net_device;
  53
  54 typedef unsigned int nf_hookfn(unsigned int hooknum,
  55                                struct sk_buff **skb,
  56                                const struct net_device *in,
  57                                const struct net_device *out,
  58                                int (*okfn)(struct sk_buff *));
  59
  60 struct nf_hook_ops
  61 {
  62         struct list_head list;
  63
  64         /* User fills in from here down. */
  65         nf_hookfn *hook;
  66         struct module *owner;
  67         int pf;
  68         int hooknum;
  69         /* Hooks are ordered in ascending priority. */
  70         int priority;
  71 };
  72
  73 struct nf_sockopt_ops
  74 {
  75         struct list_head list;
  76
  77         int pf;
  78
  79         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  80         int set_optmin;
  81         int set_optmax;
  82         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  83
  84         int get_optmin;
  85         int get_optmax;
  86         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  87
  88         /* Number of users inside set() or get(). */
  89         unsigned int use;
  90         struct task_struct *cleanup_task;
  91 };
  92
  93 /* Each queued (to userspace) skbuff has one of these. */
  94 struct nf_info
  95 {
  96         /* The ops struct which sent us to userspace. */
  97         struct nf_hook_ops *elem;
  98
  99         /* If we're sent to userspace, this keeps housekeeping info */
 100         int pf;
 101         unsigned int hook;
 102         struct net_device *indev, *outdev;
 103         int (*okfn)(struct sk_buff *);
 104 };
 105
 106 /* Function to register/unregister hook points. */
 107 int nf_register_hook(struct nf_hook_ops *reg);
 108 void nf_unregister_hook(struct nf_hook_ops *reg);
 109
 110 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 111    need to check permissions yourself! */
 112 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 113 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 114
 115 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 116
 117 typedef void nf_logfn(unsigned int hooknum,
 118                       const struct sk_buff *skb,
 119                       const struct net_device *in,
 120                       const struct net_device *out,
 121                       const char *prefix);
 122
 123 /* Function to register/unregister log function. */
 124 int nf_log_register(int pf, nf_logfn *logfn);
 125 void nf_log_unregister(int pf, nf_logfn *logfn);
 126
 127 /* Calls the registered backend logging function */
 128 void nf_log_packet(int pf,
 129                    unsigned int hooknum,
 130                    const struct sk_buff *skb,
 131                    const struct net_device *in,
 132                    const struct net_device *out,
 133                    const char *fmt, ...);
 134
 135 /* Activate hook; either okfn or kfree_skb called, unless a hook
 136    returns NF_STOLEN (in which case, it's up to the hook to deal with
 137    the consequences).
 138
 139    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 140    accepted.
 141 */
 142
 143 /* RR:
 144    > I don't want nf_hook to return anything because people might forget
 145    > about async and trust the return value to mean "packet was ok".
 146
 147    AK:
 148    Just document it clearly, then you can expect some sense from kernel
 149    coders :)
 150 */
 151
 152 /* This is gross, but inline doesn't cut it for avoiding the function
 153    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 154 #ifdef CONFIG_NETFILTER_DEBUG
 155 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                            \
 156 ({int __ret;                                                                   \
 157 if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
 158         __ret = (okfn)(skb);                                                   \
 159 __ret;})
 160 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 161 ({int __ret;                                                                   \
 162 if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1)  \
 163         __ret = (okfn)(skb);                                                   \
 164 __ret;})
 165 #else
 166 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn)                            \
 167 ({int __ret;                                                                   \
 168 if (list_empty(&nf_hooks[pf][hook]) ||                                         \
 169     (__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
 170         __ret = (okfn)(skb);                                                   \
 171 __ret;})
 172 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 173 ({int __ret;                                                                   \
 174 if (list_empty(&nf_hooks[pf][hook]) ||                                         \
 175     (__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1)  \
 176         __ret = (okfn)(skb);                                                   \
 177 __ret;})
 178 #endif
 179
 180 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
 181                  struct net_device *indev, struct net_device *outdev,
 182                  int (*okfn)(struct sk_buff *), int thresh);
 183
 184 /* Call setsockopt() */
 185 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 186                   int len);
 187 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 188                   int *len);
 189
 190 /* Packet queuing */
 191 typedef int (*nf_queue_outfn_t)(struct sk_buff *skb,
 192                                 struct nf_info *info,
 193                                 unsigned int queuenum, void *data);
 194 extern int nf_register_queue_handler(int pf,
 195                                      nf_queue_outfn_t outfn, void *data);
 196 extern int nf_unregister_queue_handler(int pf);
 197 extern void nf_unregister_queue_handlers(nf_queue_outfn_t outfn);
 198 extern void nf_reinject(struct sk_buff *skb,
 199                         struct nf_info *info,
 200                         unsigned int verdict);
 201
 202 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 203 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 204
 205 /* FIXME: Before cache is ever used, this must be implemented for real. */
 206 extern void nf_invalidate_cache(int pf);
 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. */
 211 extern int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len);
 212
 213 struct nf_queue_rerouter {
 214         void (*save)(const struct sk_buff *skb, struct nf_info *info);
 215         int (*reroute)(struct sk_buff **skb, const struct nf_info *info);
 216         int rer_size;
 217 };
 218
 219 #define nf_info_reroute(x) ((void *)x + sizeof(struct nf_info))
 220
 221 extern int nf_register_queue_rerouter(int pf, struct nf_queue_rerouter *rer);
 222 extern int nf_unregister_queue_rerouter(int pf);
 223
 224 #else /* !CONFIG_NETFILTER */
 225 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 226 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 227 #endif /*CONFIG_NETFILTER*/
 228
 229 #endif /*__KERNEL__*/
 230 #endif /*__LINUX_NETFILTER_H*/