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/in.h>
  11 #include <linux/in6.h>
  12 #include <linux/wait.h>
  13 #include <linux/list.h>
  14 #endif
  15 #include <linux/compiler.h>
  16
  17 /* Responses from hook functions. */
  18 #define NF_DROP 0
  19 #define NF_ACCEPT 1
  20 #define NF_STOLEN 2
  21 #define NF_QUEUE 3
  22 #define NF_REPEAT 4
  23 #define NF_STOP 5
  24 #define NF_MAX_VERDICT NF_STOP
  25
  26 /* we overload the higher bits for encoding auxiliary data such as the queue
  27  * number. Not nice, but better than additional function arguments. */
  28 #define NF_VERDICT_MASK 0x0000ffff
  29 #define NF_VERDICT_BITS 16
  30
  31 #define NF_VERDICT_QMASK 0xffff0000
  32 #define NF_VERDICT_QBITS 16
  33
  34 #define NF_QUEUE_NR(x) (((x << NF_VERDICT_QBITS) & NF_VERDICT_QMASK) | NF_QUEUE)
  35
  36 /* only for userspace compatibility */
  37 #ifndef __KERNEL__
  38 /* Generic cache responses from hook functions.
  39    <= 0x2000 is used for protocol-flags. */
  40 #define NFC_UNKNOWN 0x4000
  41 #define NFC_ALTERED 0x8000
  42 #endif
  43
  44 enum nf_inet_hooks {
  45         NF_INET_PRE_ROUTING,
  46         NF_INET_LOCAL_IN,
  47         NF_INET_FORWARD,
  48         NF_INET_LOCAL_OUT,
  49         NF_INET_POST_ROUTING,
  50         NF_INET_NUMHOOKS
  51 };
  52
  53 union nf_inet_addr {
  54         u_int32_t       all[4];
  55         __be32          ip;
  56         __be32          ip6[4];
  57         struct in_addr  in;
  58         struct in6_addr in6;
  59 };
  60
  61 #ifdef __KERNEL__
  62 #ifdef CONFIG_NETFILTER
  63
  64 extern void netfilter_init(void);
  65
  66 /* Largest hook number + 1 */
  67 #define NF_MAX_HOOKS 8
  68
  69 struct sk_buff;
  70 struct net_device;
  71
  72 typedef unsigned int nf_hookfn(unsigned int hooknum,
  73                                struct sk_buff *skb,
  74                                const struct net_device *in,
  75                                const struct net_device *out,
  76                                int (*okfn)(struct sk_buff *));
  77
  78 struct nf_hook_ops
  79 {
  80         struct list_head list;
  81
  82         /* User fills in from here down. */
  83         nf_hookfn *hook;
  84         struct module *owner;
  85         int pf;
  86         int hooknum;
  87         /* Hooks are ordered in ascending priority. */
  88         int priority;
  89 };
  90
  91 struct nf_sockopt_ops
  92 {
  93         struct list_head list;
  94
  95         int pf;
  96
  97         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  98         int set_optmin;
  99         int set_optmax;
 100         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 101         int (*compat_set)(struct sock *sk, int optval,
 102                         void __user *user, unsigned int len);
 103
 104         int get_optmin;
 105         int get_optmax;
 106         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 107         int (*compat_get)(struct sock *sk, int optval,
 108                         void __user *user, int *len);
 109
 110         /* Use the module struct to lock set/get code in place */
 111         struct module *owner;
 112 };
 113
 114 /* Function to register/unregister hook points. */
 115 int nf_register_hook(struct nf_hook_ops *reg);
 116 void nf_unregister_hook(struct nf_hook_ops *reg);
 117 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 118 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 119
 120 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 121    need to check permissions yourself! */
 122 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 123 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 124
 125 #ifdef CONFIG_SYSCTL
 126 /* Sysctl registration */
 127 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 128 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 129 #endif /* CONFIG_SYSCTL */
 130
 131 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 132
 133 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 134                  struct net_device *indev, struct net_device *outdev,
 135                  int (*okfn)(struct sk_buff *), int thresh);
 136
 137 /**
 138  *      nf_hook_thresh - call a netfilter hook
 139  *
 140  *      Returns 1 if the hook has allowed the packet to pass.  The function
 141  *      okfn must be invoked by the caller in this case.  Any other return
 142  *      value indicates the packet has been consumed by the hook.
 143  */
 144 static inline int nf_hook_thresh(int pf, unsigned int hook,
 145                                  struct sk_buff *skb,
 146                                  struct net_device *indev,
 147                                  struct net_device *outdev,
 148                                  int (*okfn)(struct sk_buff *), int thresh,
 149                                  int cond)
 150 {
 151         if (!cond)
 152                 return 1;
 153 #ifndef CONFIG_NETFILTER_DEBUG
 154         if (list_empty(&nf_hooks[pf][hook]))
 155                 return 1;
 156 #endif
 157         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 158 }
 159
 160 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 161                           struct net_device *indev, struct net_device *outdev,
 162                           int (*okfn)(struct sk_buff *))
 163 {
 164         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 165 }
 166
 167 /* Activate hook; either okfn or kfree_skb called, unless a hook
 168    returns NF_STOLEN (in which case, it's up to the hook to deal with
 169    the consequences).
 170
 171    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 172    accepted.
 173 */
 174
 175 /* RR:
 176    > I don't want nf_hook to return anything because people might forget
 177    > about async and trust the return value to mean "packet was ok".
 178
 179    AK:
 180    Just document it clearly, then you can expect some sense from kernel
 181    coders :)
 182 */
 183
 184 /* This is gross, but inline doesn't cut it for avoiding the function
 185    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 186
 187 /* HX: It's slightly less gross now. */
 188
 189 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 190 ({int __ret;                                                                   \
 191 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 192         __ret = (okfn)(skb);                                                   \
 193 __ret;})
 194
 195 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 196 ({int __ret;                                                                   \
 197 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 198         __ret = (okfn)(skb);                                                   \
 199 __ret;})
 200
 201 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 202         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 203
 204 /* Call setsockopt() */
 205 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 206                   int len);
 207 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 208                   int *len);
 209
 210 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 211                 char __user *opt, int len);
 212 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 213                 char __user *opt, int *len);
 214
 215 /* Call this before modifying an existing packet: ensures it is
 216    modifiable and linear to the point you care about (writable_len).
 217    Returns true or false. */
 218 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 219
 220 struct flowi;
 221 struct nf_queue_entry;
 222
 223 struct nf_afinfo {
 224         unsigned short  family;
 225         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 226                                     unsigned int dataoff, u_int8_t protocol);
 227         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 228         void            (*saveroute)(const struct sk_buff *skb,
 229                                      struct nf_queue_entry *entry);
 230         int             (*reroute)(struct sk_buff *skb,
 231                                    const struct nf_queue_entry *entry);
 232         int             route_key_size;
 233 };
 234
 235 extern const struct nf_afinfo *nf_afinfo[NPROTO];
 236 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 237 {
 238         return rcu_dereference(nf_afinfo[family]);
 239 }
 240
 241 static inline __sum16
 242 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 243             u_int8_t protocol, unsigned short family)
 244 {
 245         const struct nf_afinfo *afinfo;
 246         __sum16 csum = 0;
 247
 248         rcu_read_lock();
 249         afinfo = nf_get_afinfo(family);
 250         if (afinfo)
 251                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 252         rcu_read_unlock();
 253         return csum;
 254 }
 255
 256 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 257 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 258
 259 #include <net/flow.h>
 260 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 261
 262 static inline void
 263 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 264 {
 265 #ifdef CONFIG_NF_NAT_NEEDED
 266         void (*decodefn)(struct sk_buff *, struct flowi *);
 267
 268         if (family == AF_INET) {
 269                 rcu_read_lock();
 270                 decodefn = rcu_dereference(ip_nat_decode_session);
 271                 if (decodefn)
 272                         decodefn(skb, fl);
 273                 rcu_read_unlock();
 274         }
 275 #endif
 276 }
 277
 278 #ifdef CONFIG_PROC_FS
 279 #include <linux/proc_fs.h>
 280 extern struct proc_dir_entry *proc_net_netfilter;
 281 #endif
 282
 283 #else /* !CONFIG_NETFILTER */
 284 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 285 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 286 static inline int nf_hook_thresh(int pf, unsigned int hook,
 287                                  struct sk_buff *skb,
 288                                  struct net_device *indev,
 289                                  struct net_device *outdev,
 290                                  int (*okfn)(struct sk_buff *), int thresh,
 291                                  int cond)
 292 {
 293         return okfn(skb);
 294 }
 295 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 296                           struct net_device *indev, struct net_device *outdev,
 297                           int (*okfn)(struct sk_buff *))
 298 {
 299         return 1;
 300 }
 301 struct flowi;
 302 static inline void
 303 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 304 #endif /*CONFIG_NETFILTER*/
 305
 306 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 307 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 308 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 309 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 310 #else
 311 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 312 #endif
 313
 314 #endif /*__KERNEL__*/
 315 #endif /*__LINUX_NETFILTER_H*/