1 #ifndef __LINUX_NETFILTER_H 2 #define __LINUX_NETFILTER_H 3 4 #ifdef __KERNEL__ 5 #include <linux/init.h> 6 #include <linux/skbuff.h> 7 #include <linux/net.h> 8 #include <linux/if.h> 9 #include <linux/in.h> 10 #include <linux/in6.h> 11 #include <linux/wait.h> 12 #include <linux/list.h> 13 #endif 14 #include <linux/types.h> 15 #include <linux/compiler.h> 16 #include <linux/sysctl.h> 17 18 /* Responses from hook functions. */ 19 #define NF_DROP 0 20 #define NF_ACCEPT 1 21 #define NF_STOLEN 2 22 #define NF_QUEUE 3 23 #define NF_REPEAT 4 24 #define NF_STOP 5 25 #define NF_MAX_VERDICT NF_STOP 26 27 /* we overload the higher bits for encoding auxiliary data such as the queue 28 * number or errno values. Not nice, but better than additional function 29 * arguments. */ 30 #define NF_VERDICT_MASK 0x000000ff 31 32 /* extra verdict flags have mask 0x0000ff00 */ 33 #define NF_VERDICT_FLAG_QUEUE_BYPASS 0x00008000 34 35 /* queue number (NF_QUEUE) or errno (NF_DROP) */ 36 #define NF_VERDICT_QMASK 0xffff0000 37 #define NF_VERDICT_QBITS 16 38 39 #define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE) 40 41 #define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP) 42 43 /* only for userspace compatibility */ 44 #ifndef __KERNEL__ 45 /* Generic cache responses from hook functions. 46 <= 0x2000 is used for protocol-flags. */ 47 #define NFC_UNKNOWN 0x4000 48 #define NFC_ALTERED 0x8000 49 50 /* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */ 51 #define NF_VERDICT_BITS 16 52 #endif 53 54 enum nf_inet_hooks { 55 NF_INET_PRE_ROUTING, 56 NF_INET_LOCAL_IN, 57 NF_INET_FORWARD, 58 NF_INET_LOCAL_OUT, 59 NF_INET_POST_ROUTING, 60 NF_INET_NUMHOOKS 61 }; 62 63 enum { 64 NFPROTO_UNSPEC = 0, 65 NFPROTO_IPV4 = 2, 66 NFPROTO_ARP = 3, 67 NFPROTO_BRIDGE = 7, 68 NFPROTO_IPV6 = 10, 69 NFPROTO_DECNET = 12, 70 NFPROTO_NUMPROTO, 71 }; 72 73 union nf_inet_addr { 74 __u32 all[4]; 75 __be32 ip; 76 __be32 ip6[4]; 77 struct in_addr in; 78 struct in6_addr in6; 79 }; 80 81 #ifdef __KERNEL__ 82 #ifdef CONFIG_NETFILTER 83 static inline int NF_DROP_GETERR(int verdict) 84 { 85 return -(verdict >> NF_VERDICT_QBITS); 86 } 87 88 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1, 89 const union nf_inet_addr *a2) 90 { 91 return a1->all[0] == a2->all[0] && 92 a1->all[1] == a2->all[1] && 93 a1->all[2] == a2->all[2] && 94 a1->all[3] == a2->all[3]; 95 } 96 97 extern void netfilter_init(void); 98 99 /* Largest hook number + 1 */ 100 #define NF_MAX_HOOKS 8 101 102 struct sk_buff; 103 104 typedef unsigned int nf_hookfn(unsigned int hooknum, 105 struct sk_buff *skb, 106 const struct net_device *in, 107 const struct net_device *out, 108 int (*okfn)(struct sk_buff *)); 109 110 struct nf_hook_ops { 111 struct list_head list; 112 113 /* User fills in from here down. */ 114 nf_hookfn *hook; 115 struct module *owner; 116 u_int8_t pf; 117 unsigned int hooknum; 118 /* Hooks are ordered in ascending priority. */ 119 int priority; 120 }; 121 122 struct nf_sockopt_ops { 123 struct list_head list; 124 125 u_int8_t pf; 126 127 /* Non-inclusive ranges: use 0/0/NULL to never get called. */ 128 int set_optmin; 129 int set_optmax; 130 int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len); 131 #ifdef CONFIG_COMPAT 132 int (*compat_set)(struct sock *sk, int optval, 133 void __user *user, unsigned int len); 134 #endif 135 int get_optmin; 136 int get_optmax; 137 int (*get)(struct sock *sk, int optval, void __user *user, int *len); 138 #ifdef CONFIG_COMPAT 139 int (*compat_get)(struct sock *sk, int optval, 140 void __user *user, int *len); 141 #endif 142 /* Use the module struct to lock set/get code in place */ 143 struct module *owner; 144 }; 145 146 /* Function to register/unregister hook points. */ 147 int nf_register_hook(struct nf_hook_ops *reg); 148 void nf_unregister_hook(struct nf_hook_ops *reg); 149 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n); 150 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n); 151 152 /* Functions to register get/setsockopt ranges (non-inclusive). You 153 need to check permissions yourself! */ 154 int nf_register_sockopt(struct nf_sockopt_ops *reg); 155 void nf_unregister_sockopt(struct nf_sockopt_ops *reg); 156 157 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS]; 158 159 #if defined(CONFIG_JUMP_LABEL) 160 #include <linux/static_key.h> 161 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS]; 162 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook) 163 { 164 if (__builtin_constant_p(pf) && 165 __builtin_constant_p(hook)) 166 return static_key_false(&nf_hooks_needed[pf][hook]); 167 168 return !list_empty(&nf_hooks[pf][hook]); 169 } 170 #else 171 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook) 172 { 173 return !list_empty(&nf_hooks[pf][hook]); 174 } 175 #endif 176 177 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb, 178 struct net_device *indev, struct net_device *outdev, 179 int (*okfn)(struct sk_buff *), int thresh); 180 181 /** 182 * nf_hook_thresh - call a netfilter hook 183 * 184 * Returns 1 if the hook has allowed the packet to pass. The function 185 * okfn must be invoked by the caller in this case. Any other return 186 * value indicates the packet has been consumed by the hook. 187 */ 188 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook, 189 struct sk_buff *skb, 190 struct net_device *indev, 191 struct net_device *outdev, 192 int (*okfn)(struct sk_buff *), int thresh) 193 { 194 if (nf_hooks_active(pf, hook)) 195 return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh); 196 return 1; 197 } 198 199 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb, 200 struct net_device *indev, struct net_device *outdev, 201 int (*okfn)(struct sk_buff *)) 202 { 203 return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN); 204 } 205 206 /* Activate hook; either okfn or kfree_skb called, unless a hook 207 returns NF_STOLEN (in which case, it's up to the hook to deal with 208 the consequences). 209 210 Returns -ERRNO if packet dropped. Zero means queued, stolen or 211 accepted. 212 */ 213 214 /* RR: 215 > I don't want nf_hook to return anything because people might forget 216 > about async and trust the return value to mean "packet was ok". 217 218 AK: 219 Just document it clearly, then you can expect some sense from kernel 220 coders :) 221 */ 222 223 static inline int 224 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb, 225 struct net_device *in, struct net_device *out, 226 int (*okfn)(struct sk_buff *), int thresh) 227 { 228 int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh); 229 if (ret == 1) 230 ret = okfn(skb); 231 return ret; 232 } 233 234 static inline int 235 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb, 236 struct net_device *in, struct net_device *out, 237 int (*okfn)(struct sk_buff *), bool cond) 238 { 239 int ret; 240 241 if (!cond || 242 ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1)) 243 ret = okfn(skb); 244 return ret; 245 } 246 247 static inline int 248 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb, 249 struct net_device *in, struct net_device *out, 250 int (*okfn)(struct sk_buff *)) 251 { 252 return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN); 253 } 254 255 /* Call setsockopt() */ 256 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt, 257 unsigned int len); 258 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt, 259 int *len); 260 #ifdef CONFIG_COMPAT 261 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, 262 char __user *opt, unsigned int len); 263 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, 264 char __user *opt, int *len); 265 #endif 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 __sum16 (*checksum_partial)(struct sk_buff *skb, 280 unsigned int hook, 281 unsigned int dataoff, 282 unsigned int len, 283 u_int8_t protocol); 284 int (*route)(struct net *net, struct dst_entry **dst, 285 struct flowi *fl, bool strict); 286 void (*saveroute)(const struct sk_buff *skb, 287 struct nf_queue_entry *entry); 288 int (*reroute)(struct sk_buff *skb, 289 const struct nf_queue_entry *entry); 290 int route_key_size; 291 }; 292 293 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO]; 294 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family) 295 { 296 return rcu_dereference(nf_afinfo[family]); 297 } 298 299 static inline __sum16 300 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff, 301 u_int8_t protocol, unsigned short family) 302 { 303 const struct nf_afinfo *afinfo; 304 __sum16 csum = 0; 305 306 rcu_read_lock(); 307 afinfo = nf_get_afinfo(family); 308 if (afinfo) 309 csum = afinfo->checksum(skb, hook, dataoff, protocol); 310 rcu_read_unlock(); 311 return csum; 312 } 313 314 static inline __sum16 315 nf_checksum_partial(struct sk_buff *skb, unsigned int hook, 316 unsigned int dataoff, unsigned int len, 317 u_int8_t protocol, unsigned short family) 318 { 319 const struct nf_afinfo *afinfo; 320 __sum16 csum = 0; 321 322 rcu_read_lock(); 323 afinfo = nf_get_afinfo(family); 324 if (afinfo) 325 csum = afinfo->checksum_partial(skb, hook, dataoff, len, 326 protocol); 327 rcu_read_unlock(); 328 return csum; 329 } 330 331 extern int nf_register_afinfo(const struct nf_afinfo *afinfo); 332 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo); 333 334 #include <net/flow.h> 335 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *); 336 337 static inline void 338 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family) 339 { 340 #ifdef CONFIG_NF_NAT_NEEDED 341 void (*decodefn)(struct sk_buff *, struct flowi *); 342 343 if (family == AF_INET) { 344 rcu_read_lock(); 345 decodefn = rcu_dereference(ip_nat_decode_session); 346 if (decodefn) 347 decodefn(skb, fl); 348 rcu_read_unlock(); 349 } 350 #endif 351 } 352 353 #ifdef CONFIG_PROC_FS 354 #include <linux/proc_fs.h> 355 extern struct proc_dir_entry *proc_net_netfilter; 356 #endif 357 358 #else /* !CONFIG_NETFILTER */ 359 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb) 360 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb) 361 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook, 362 struct sk_buff *skb, 363 struct net_device *indev, 364 struct net_device *outdev, 365 int (*okfn)(struct sk_buff *), int thresh) 366 { 367 return okfn(skb); 368 } 369 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb, 370 struct net_device *indev, struct net_device *outdev, 371 int (*okfn)(struct sk_buff *)) 372 { 373 return 1; 374 } 375 struct flowi; 376 static inline void 377 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family) 378 { 379 } 380 #endif /*CONFIG_NETFILTER*/ 381 382 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) 383 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu; 384 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *); 385 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu; 386 #else 387 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {} 388 #endif 389 390 #endif /*__KERNEL__*/ 391 #endif /*__LINUX_NETFILTER_H*/ 392