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 enum nf_inet_hooks {
  43         NF_INET_PRE_ROUTING,
  44         NF_INET_LOCAL_IN,
  45         NF_INET_FORWARD,
  46         NF_INET_LOCAL_OUT,
  47         NF_INET_POST_ROUTING,
  48         NF_INET_NUMHOOKS
  49 };
  50
  51 #ifdef __KERNEL__
  52 #ifdef CONFIG_NETFILTER
  53
  54 extern void netfilter_init(void);
  55
  56 /* Largest hook number + 1 */
  57 #define NF_MAX_HOOKS 8
  58
  59 struct sk_buff;
  60 struct net_device;
  61
  62 typedef unsigned int nf_hookfn(unsigned int hooknum,
  63                                struct sk_buff *skb,
  64                                const struct net_device *in,
  65                                const struct net_device *out,
  66                                int (*okfn)(struct sk_buff *));
  67
  68 struct nf_hook_ops
  69 {
  70         struct list_head list;
  71
  72         /* User fills in from here down. */
  73         nf_hookfn *hook;
  74         struct module *owner;
  75         int pf;
  76         int hooknum;
  77         /* Hooks are ordered in ascending priority. */
  78         int priority;
  79 };
  80
  81 struct nf_sockopt_ops
  82 {
  83         struct list_head list;
  84
  85         int pf;
  86
  87         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
  88         int set_optmin;
  89         int set_optmax;
  90         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
  91         int (*compat_set)(struct sock *sk, int optval,
  92                         void __user *user, unsigned int len);
  93
  94         int get_optmin;
  95         int get_optmax;
  96         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
  97         int (*compat_get)(struct sock *sk, int optval,
  98                         void __user *user, int *len);
  99
 100         /* Use the module struct to lock set/get code in place */
 101         struct module *owner;
 102 };
 103
 104 /* Function to register/unregister hook points. */
 105 int nf_register_hook(struct nf_hook_ops *reg);
 106 void nf_unregister_hook(struct nf_hook_ops *reg);
 107 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 108 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 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 #ifdef CONFIG_SYSCTL
 116 /* Sysctl registration */
 117 struct ctl_table_header *nf_register_sysctl_table(struct ctl_table *path,
 118                                                   struct ctl_table *table);
 119 void nf_unregister_sysctl_table(struct ctl_table_header *header,
 120                                 struct ctl_table *table);
 121 extern struct ctl_table nf_net_netfilter_sysctl_path[];
 122 extern struct ctl_table nf_net_ipv4_netfilter_sysctl_path[];
 123 #endif /* CONFIG_SYSCTL */
 124
 125 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 126
 127 /* those NF_LOG_* defines and struct nf_loginfo are legacy definitios that will
 128  * disappear once iptables is replaced with pkttables.  Please DO NOT use them
 129  * for any new code! */
 130 #define NF_LOG_TCPSEQ           0x01    /* Log TCP sequence numbers */
 131 #define NF_LOG_TCPOPT           0x02    /* Log TCP options */
 132 #define NF_LOG_IPOPT            0x04    /* Log IP options */
 133 #define NF_LOG_UID              0x08    /* Log UID owning local socket */
 134 #define NF_LOG_MASK             0x0f
 135
 136 #define NF_LOG_TYPE_LOG         0x01
 137 #define NF_LOG_TYPE_ULOG        0x02
 138
 139 struct nf_loginfo {
 140         u_int8_t type;
 141         union {
 142                 struct {
 143                         u_int32_t copy_len;
 144                         u_int16_t group;
 145                         u_int16_t qthreshold;
 146                 } ulog;
 147                 struct {
 148                         u_int8_t level;
 149                         u_int8_t logflags;
 150                 } log;
 151         } u;
 152 };
 153
 154 typedef void nf_logfn(unsigned int pf,
 155                       unsigned int hooknum,
 156                       const struct sk_buff *skb,
 157                       const struct net_device *in,
 158                       const struct net_device *out,
 159                       const struct nf_loginfo *li,
 160                       const char *prefix);
 161
 162 struct nf_logger {
 163         struct module   *me;
 164         nf_logfn        *logfn;
 165         char            *name;
 166 };
 167
 168 /* Function to register/unregister log function. */
 169 int nf_log_register(int pf, struct nf_logger *logger);
 170 void nf_log_unregister(struct nf_logger *logger);
 171 void nf_log_unregister_pf(int pf);
 172
 173 /* Calls the registered backend logging function */
 174 void nf_log_packet(int pf,
 175                    unsigned int hooknum,
 176                    const struct sk_buff *skb,
 177                    const struct net_device *in,
 178                    const struct net_device *out,
 179                    struct nf_loginfo *li,
 180                    const char *fmt, ...);
 181
 182 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
 183                  struct net_device *indev, struct net_device *outdev,
 184                  int (*okfn)(struct sk_buff *), int thresh);
 185
 186 /**
 187  *      nf_hook_thresh - call a netfilter hook
 188  *
 189  *      Returns 1 if the hook has allowed the packet to pass.  The function
 190  *      okfn must be invoked by the caller in this case.  Any other return
 191  *      value indicates the packet has been consumed by the hook.
 192  */
 193 static inline int nf_hook_thresh(int pf, unsigned int hook,
 194                                  struct sk_buff *skb,
 195                                  struct net_device *indev,
 196                                  struct net_device *outdev,
 197                                  int (*okfn)(struct sk_buff *), int thresh,
 198                                  int cond)
 199 {
 200         if (!cond)
 201                 return 1;
 202 #ifndef CONFIG_NETFILTER_DEBUG
 203         if (list_empty(&nf_hooks[pf][hook]))
 204                 return 1;
 205 #endif
 206         return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 207 }
 208
 209 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 210                           struct net_device *indev, struct net_device *outdev,
 211                           int (*okfn)(struct sk_buff *))
 212 {
 213         return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
 214 }
 215
 216 /* Activate hook; either okfn or kfree_skb called, unless a hook
 217    returns NF_STOLEN (in which case, it's up to the hook to deal with
 218    the consequences).
 219
 220    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 221    accepted.
 222 */
 223
 224 /* RR:
 225    > I don't want nf_hook to return anything because people might forget
 226    > about async and trust the return value to mean "packet was ok".
 227
 228    AK:
 229    Just document it clearly, then you can expect some sense from kernel
 230    coders :)
 231 */
 232
 233 /* This is gross, but inline doesn't cut it for avoiding the function
 234    call in fast path: gcc doesn't inline (needs value tracking?). --RR */
 235
 236 /* HX: It's slightly less gross now. */
 237
 238 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)             \
 239 ({int __ret;                                                                   \
 240 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
 241         __ret = (okfn)(skb);                                                   \
 242 __ret;})
 243
 244 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
 245 ({int __ret;                                                                   \
 246 if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
 247         __ret = (okfn)(skb);                                                   \
 248 __ret;})
 249
 250 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
 251         NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
 252
 253 /* Call setsockopt() */
 254 int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 255                   int len);
 256 int nf_getsockopt(struct sock *sk, int pf, int optval, char __user *opt,
 257                   int *len);
 258
 259 int compat_nf_setsockopt(struct sock *sk, int pf, int optval,
 260                 char __user *opt, int len);
 261 int compat_nf_getsockopt(struct sock *sk, int pf, int optval,
 262                 char __user *opt, int *len);
 263
 264 /* FIXME: Before cache is ever used, this must be implemented for real. */
 265 extern void nf_invalidate_cache(int pf);
 266
 267 /* Call this before modifying an existing packet: ensures it is
 268    modifiable and linear to the point you care about (writable_len).
 269    Returns true or false. */
 270 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 271
 272 struct flowi;
 273 struct nf_queue_entry;
 274
 275 struct nf_afinfo {
 276         unsigned short  family;
 277         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 278                                     unsigned int dataoff, u_int8_t protocol);
 279         int             (*route)(struct dst_entry **dst, struct flowi *fl);
 280         void            (*saveroute)(const struct sk_buff *skb,
 281                                      struct nf_queue_entry *entry);
 282         int             (*reroute)(struct sk_buff *skb,
 283                                    const struct nf_queue_entry *entry);
 284         int             route_key_size;
 285 };
 286
 287 extern struct nf_afinfo *nf_afinfo[];
 288 static inline struct nf_afinfo *nf_get_afinfo(unsigned short family)
 289 {
 290         return rcu_dereference(nf_afinfo[family]);
 291 }
 292
 293 static inline __sum16
 294 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 295             u_int8_t protocol, unsigned short family)
 296 {
 297         struct nf_afinfo *afinfo;
 298         __sum16 csum = 0;
 299
 300         rcu_read_lock();
 301         afinfo = nf_get_afinfo(family);
 302         if (afinfo)
 303                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 304         rcu_read_unlock();
 305         return csum;
 306 }
 307
 308 extern int nf_register_afinfo(struct nf_afinfo *afinfo);
 309 extern void nf_unregister_afinfo(struct nf_afinfo *afinfo);
 310
 311 #include <net/flow.h>
 312 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
 313
 314 static inline void
 315 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family)
 316 {
 317 #if defined(CONFIG_IP_NF_NAT_NEEDED) || defined(CONFIG_NF_NAT_NEEDED)
 318         void (*decodefn)(struct sk_buff *, struct flowi *);
 319
 320         if (family == AF_INET && (decodefn = ip_nat_decode_session) != NULL)
 321                 decodefn(skb, fl);
 322 #endif
 323 }
 324
 325 #ifdef CONFIG_PROC_FS
 326 #include <linux/proc_fs.h>
 327 extern struct proc_dir_entry *proc_net_netfilter;
 328 #endif
 329
 330 #else /* !CONFIG_NETFILTER */
 331 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 332 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 333 static inline int nf_hook_thresh(int pf, unsigned int hook,
 334                                  struct sk_buff *skb,
 335                                  struct net_device *indev,
 336                                  struct net_device *outdev,
 337                                  int (*okfn)(struct sk_buff *), int thresh,
 338                                  int cond)
 339 {
 340         return okfn(skb);
 341 }
 342 static inline int nf_hook(int pf, unsigned int hook, struct sk_buff *skb,
 343                           struct net_device *indev, struct net_device *outdev,
 344                           int (*okfn)(struct sk_buff *))
 345 {
 346         return 1;
 347 }
 348 struct flowi;
 349 static inline void
 350 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, int family) {}
 351 #endif /*CONFIG_NETFILTER*/
 352
 353 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 354 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 355 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 356 extern void (*nf_ct_destroy)(struct nf_conntrack *);
 357 #else
 358 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 359 #endif
 360
 361 #endif /*__KERNEL__*/
 362 #endif /*__LINUX_NETFILTER_H*/