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_BITS) & 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         __u32           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 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  65                                    const union nf_inet_addr *a2)
  66 {
  67         return a1->all[0] == a2->all[0] &&
  68                a1->all[1] == a2->all[1] &&
  69                a1->all[2] == a2->all[2] &&
  70                a1->all[3] == a2->all[3];
  71 }
  72
  73 extern void netfilter_init(void);
  74
  75 /* Largest hook number + 1 */
  76 #define NF_MAX_HOOKS 8
  77
  78 struct sk_buff;
  79 struct net_device;
  80
  81 typedef unsigned int nf_hookfn(unsigned int hooknum,
  82                                struct sk_buff *skb,
  83                                const struct net_device *in,
  84                                const struct net_device *out,
  85                                int (*okfn)(struct sk_buff *));
  86
  87 struct nf_hook_ops
  88 {
  89         struct list_head list;
  90
  91         /* User fills in from here down. */
  92         nf_hookfn *hook;
  93         struct module *owner;
  94         int pf;
  95         int hooknum;
  96         /* Hooks are ordered in ascending priority. */
  97         int priority;
  98 };
  99
 100 struct nf_sockopt_ops
 101 {
 102         struct list_head list;
 103
 104         int pf;
 105
 106         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 107         int set_optmin;
 108         int set_optmax;
 109         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 110         int (*compat_set)(struct sock *sk, int optval,
 111                         void __user *user, unsigned int len);
 112
 113         int get_optmin;
 114         int get_optmax;
 115         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 116         int (*compat_get)(struct sock *sk, int optval,
 117                         void __user *user, int *len);
 118
 119         /* Use the module struct to lock set/get code in place */
 120         struct module *owner;
 121 };
 122
 123 /* Function to register/unregister hook points. */
 124 int nf_register_hook(struct nf_hook_ops *reg);
 125 void nf_unregister_hook(struct nf_hook_ops *reg);
 126 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 127 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 128
 129 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 130    need to check permissions yourself! */
 131 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 132 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 133
 134 #ifdef CONFIG_SYSCTL
 135 /* Sysctl registration */
 136 extern struct ctl_path nf_net_netfilter_sysctl_path[];
 137 extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
 138 #endif /* CONFIG_SYSCTL */
 139
 140 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 141
 142 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 143                  struct net_device *indev, struct net_device *outdev,
 144                  int (*okfn)(struct sk_buff *), int thresh);
 145
 146 /**
 147  *      nf_hook_thresh - call a netfilter hook
 148  *
 149  *      Returns 1 if the hook has allowed the packet to pass.  The function
 150  *      okfn must be invoked by the caller in this case.  Any other return
 151  *      value indicates the packet has been consumed by the hook.
 152  */
 153 static inline int nf_hook_thresh(int pf, unsigned int hook,
 154                                  struct sk_buff *skb,
 155                                  struct net_device *indev,
 156                                  struct net_device *outdev,
 157                                  int (*okfn)(struct sk_buff *), int thresh,
 158                                  int cond)
 159 {
 160         if (!cond)
 161                 return 1;
 162 #ifndef CONFIG_NETFILTER_DEBUG
 163         if (list_empty(&nf_hooks[pf][hook]))
 164                 return 1;
 165 #endif
 166         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 167 }
 168
 169 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 170                           struct net_device *indev, struct net_device *outdev,
 171                           int (*okfn)(struct sk_buff *))
 172 {
 173         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 174 }
 175
 176 /* Activate hook; either okfn or kfree_skb called, unless a hook
 177    returns NF_STOLEN (in which case, it's up to the hook to deal with
 178    the consequences).
 179
 180    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 181    accepted.
 182 */
 183
 184 /* RR:
 185    > I don't want nf_hook to return anything because people might forget
 186    > about async and trust the return value to mean "packet was ok".
 187
 188    AK:
 189    Just document it clearly, then you can expect some sense from kernel
 190    coders :)
 191 */
 192
 193 /* This is gross, but inline doesn't cut it for avoiding the function
 194    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 195
 196 /* HX: It's slightly less gross now. */
 197
 198 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 199 ({int __ret;                                                                   \
 200 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 201         __ret = (okfn)(skb);                                                   \
 202 __ret;})
 203
 204 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 205 ({int __ret;                                                                   \
 206 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 207         __ret = (okfn)(skb);                                                   \
 208 __ret;})
 209
 210 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 211         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 212
 213 /* Call setsockopt() */
 214 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 215                   int len);
 216 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 217                   int *len);
 218
 219 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 220                 char __user *opt, int len);
 221 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 222                 char __user *opt, int *len);
 223
 224 /* Call this before modifying an existing packet: ensures it is
 225    modifiable and linear to the point you care about (writable_len).
 226    Returns true or false. */
 227 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 228
 229 struct flowi;
 230 struct nf_queue_entry;
 231
 232 struct nf_afinfo {
 233         unsigned short  family;
 234         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 235                                     unsigned int dataoff, u_int8_t protocol);
 236         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 237         void            (*saveroute)(const struct sk_buff *skb,
 238                                      struct nf_queue_entry *entry);
 239         int             (*reroute)(struct sk_buff *skb,
 240                                    const struct nf_queue_entry *entry);
 241         int             route_key_size;
 242 };
 243
 244 extern const struct nf_afinfo *nf_afinfo[NPROTO];
 245 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 246 {
 247         return rcu_dereference(nf_afinfo[family]);
 248 }
 249
 250 static inline __sum16
 251 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 252             u_int8_t protocol, unsigned short family)
 253 {
 254         const struct nf_afinfo *afinfo;
 255         __sum16 csum = 0;
 256
 257         rcu_read_lock();
 258         afinfo = nf_get_afinfo(family);
 259         if (afinfo)
 260                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 261         rcu_read_unlock();
 262         return csum;
 263 }
 264
 265 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 266 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 267
 268 #include <net/flow.h>
 269 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 270
 271 static inline void
 272 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 273 {
 274 #ifdef CONFIG_NF_NAT_NEEDED
 275         void (*decodefn)(struct sk_buff *, struct flowi *);
 276
 277         if (family == AF_INET) {
 278                 rcu_read_lock();
 279                 decodefn = rcu_dereference(ip_nat_decode_session);
 280                 if (decodefn)
 281                         decodefn(skb, fl);
 282                 rcu_read_unlock();
 283         }
 284 #endif
 285 }
 286
 287 #ifdef CONFIG_PROC_FS
 288 #include <linux/proc_fs.h>
 289 extern struct proc_dir_entry *proc_net_netfilter;
 290 #endif
 291
 292 #else /* !CONFIG_NETFILTER */
 293 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 294 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 295 static inline int nf_hook_thresh(int pf, unsigned int hook,
 296                                  struct sk_buff *skb,
 297                                  struct net_device *indev,
 298                                  struct net_device *outdev,
 299                                  int (*okfn)(struct sk_buff *), int thresh,
 300                                  int cond)
 301 {
 302         return okfn(skb);
 303 }
 304 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 305                           struct net_device *indev, struct net_device *outdev,
 306                           int (*okfn)(struct sk_buff *))
 307 {
 308         return 1;
 309 }
 310 struct flowi;
 311 static inline void
 312 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 313 #endif /*CONFIG_NETFILTER*/
 314
 315 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 316 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 317 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 318 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 319 #else
 320 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 321 #endif
 322
 323 #endif /*__KERNEL__*/
 324 #endif /*__LINUX_NETFILTER_H*/