include/linux/netfilter.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __LINUX_NETFILTER_H
   3 #define __LINUX_NETFILTER_H
   4
   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 #include <linux/static_key.h>
  14 #include <linux/module.h>
  15 #include <linux/netfilter_defs.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/sockptr.h>
  18 #include <net/net_namespace.h>
  19
  20 static inline int NF_DROP_GETERR(int verdict)
  21 {
  22         return -(verdict >> NF_VERDICT_QBITS);
  23 }
  24
  25 static __always_inline int
  26 NF_DROP_REASON(struct sk_buff *skb, enum skb_drop_reason reason, u32 err)
  27 {
  28         BUILD_BUG_ON(err > 0xffff);
  29
  30         kfree_skb_reason(skb, reason);
  31
  32         return ((err << 16) | NF_STOLEN);
  33 }
  34
  35 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  36                                    const union nf_inet_addr *a2)
  37 {
  38 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
  39         const unsigned long *ul1 = (const unsigned long *)a1;
  40         const unsigned long *ul2 = (const unsigned long *)a2;
  41
  42         return ((ul1[0] ^ ul2[0]) | (ul1[1] ^ ul2[1])) == 0UL;
  43 #else
  44         return a1->all[0] == a2->all[0] &&
  45                a1->all[1] == a2->all[1] &&
  46                a1->all[2] == a2->all[2] &&
  47                a1->all[3] == a2->all[3];
  48 #endif
  49 }
  50
  51 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  52                                      union nf_inet_addr *result,
  53                                      const union nf_inet_addr *mask)
  54 {
  55 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
  56         const unsigned long *ua = (const unsigned long *)a1;
  57         unsigned long *ur = (unsigned long *)result;
  58         const unsigned long *um = (const unsigned long *)mask;
  59
  60         ur[0] = ua[0] & um[0];
  61         ur[1] = ua[1] & um[1];
  62 #else
  63         result->all[0] = a1->all[0] & mask->all[0];
  64         result->all[1] = a1->all[1] & mask->all[1];
  65         result->all[2] = a1->all[2] & mask->all[2];
  66         result->all[3] = a1->all[3] & mask->all[3];
  67 #endif
  68 }
  69
  70 int netfilter_init(void);
  71
  72 struct sk_buff;
  73
  74 struct nf_hook_ops;
  75
  76 struct sock;
  77
  78 struct nf_hook_state {
  79         u8 hook;
  80         u8 pf;
  81         struct net_device *in;
  82         struct net_device *out;
  83         struct sock *sk;
  84         struct net *net;
  85         int (*okfn)(struct net *, struct sock *, struct sk_buff *);
  86 };
  87
  88 typedef unsigned int nf_hookfn(void *priv,
  89                                struct sk_buff *skb,
  90                                const struct nf_hook_state *state);
  91 enum nf_hook_ops_type {
  92         NF_HOOK_OP_UNDEFINED,
  93         NF_HOOK_OP_NF_TABLES,
  94         NF_HOOK_OP_BPF,
  95 };
  96
  97 struct nf_hook_ops {
  98         /* User fills in from here down. */
  99         nf_hookfn               *hook;
 100         struct net_device       *dev;
 101         void                    *priv;
 102         u8                      pf;
 103         enum nf_hook_ops_type   hook_ops_type:8;
 104         unsigned int            hooknum;
 105         /* Hooks are ordered in ascending priority. */
 106         int                     priority;
 107 };
 108
 109 struct nf_hook_entry {
 110         nf_hookfn                       *hook;
 111         void                            *priv;
 112 };
 113
 114 struct nf_hook_entries_rcu_head {
 115         struct rcu_head head;
 116         void    *allocation;
 117 };
 118
 119 struct nf_hook_entries {
 120         u16                             num_hook_entries;
 121         /* padding */
 122         struct nf_hook_entry            hooks[];
 123
 124         /* trailer: pointers to original orig_ops of each hook,
 125          * followed by rcu_head and scratch space used for freeing
 126          * the structure via call_rcu.
 127          *
 128          *   This is not part of struct nf_hook_entry since its only
 129          *   needed in slow path (hook register/unregister):
 130          * const struct nf_hook_ops     *orig_ops[]
 131          *
 132          *   For the same reason, we store this at end -- its
 133          *   only needed when a hook is deleted, not during
 134          *   packet path processing:
 135          * struct nf_hook_entries_rcu_head     head
 136          */
 137 };
 138
 139 #ifdef CONFIG_NETFILTER
 140 static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
 141 {
 142         unsigned int n = e->num_hook_entries;
 143         const void *hook_end;
 144
 145         hook_end = &e->hooks[n]; /* this is *past* ->hooks[]! */
 146
 147         return (struct nf_hook_ops **)hook_end;
 148 }
 149
 150 static inline int
 151 nf_hook_entry_hookfn(const struct nf_hook_entry *entry, struct sk_buff *skb,
 152                      struct nf_hook_state *state)
 153 {
 154         return entry->hook(entry->priv, skb, state);
 155 }
 156
 157 static inline void nf_hook_state_init(struct nf_hook_state *p,
 158                                       unsigned int hook,
 159                                       u_int8_t pf,
 160                                       struct net_device *indev,
 161                                       struct net_device *outdev,
 162                                       struct sock *sk,
 163                                       struct net *net,
 164                                       int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 165 {
 166         p->hook = hook;
 167         p->pf = pf;
 168         p->in = indev;
 169         p->out = outdev;
 170         p->sk = sk;
 171         p->net = net;
 172         p->okfn = okfn;
 173 }
 174
 175
 176
 177 struct nf_sockopt_ops {
 178         struct list_head list;
 179
 180         u_int8_t pf;
 181
 182         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 183         int set_optmin;
 184         int set_optmax;
 185         int (*set)(struct sock *sk, int optval, sockptr_t arg,
 186                    unsigned int len);
 187         int get_optmin;
 188         int get_optmax;
 189         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 190         /* Use the module struct to lock set/get code in place */
 191         struct module *owner;
 192 };
 193
 194 /* Function to register/unregister hook points. */
 195 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
 196 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
 197 int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 198                           unsigned int n);
 199 void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 200                              unsigned int n);
 201
 202 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 203    need to check permissions yourself! */
 204 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 205 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 206
 207 #ifdef CONFIG_JUMP_LABEL
 208 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 209 #endif
 210
 211 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
 212                  const struct nf_hook_entries *e, unsigned int i);
 213
 214 void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
 215                        const struct nf_hook_entries *e);
 216 /**
 217  *      nf_hook - call a netfilter hook
 218  *
 219  *      Returns 1 if the hook has allowed the packet to pass.  The function
 220  *      okfn must be invoked by the caller in this case.  Any other return
 221  *      value indicates the packet has been consumed by the hook.
 222  */
 223 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 224                           struct sock *sk, struct sk_buff *skb,
 225                           struct net_device *indev, struct net_device *outdev,
 226                           int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 227 {
 228         struct nf_hook_entries *hook_head = NULL;
 229         int ret = 1;
 230
 231 #ifdef CONFIG_JUMP_LABEL
 232         if (__builtin_constant_p(pf) &&
 233             __builtin_constant_p(hook) &&
 234             !static_key_false(&nf_hooks_needed[pf][hook]))
 235                 return 1;
 236 #endif
 237
 238         rcu_read_lock();
 239         switch (pf) {
 240         case NFPROTO_IPV4:
 241                 hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
 242                 break;
 243         case NFPROTO_IPV6:
 244                 hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
 245                 break;
 246         case NFPROTO_ARP:
 247 #ifdef CONFIG_NETFILTER_FAMILY_ARP
 248                 if (WARN_ON_ONCE(hook >= ARRAY_SIZE(net->nf.hooks_arp)))
 249                         break;
 250                 hook_head = rcu_dereference(net->nf.hooks_arp[hook]);
 251 #endif
 252                 break;
 253         case NFPROTO_BRIDGE:
 254 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 255                 hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
 256 #endif
 257                 break;
 258         default:
 259                 WARN_ON_ONCE(1);
 260                 break;
 261         }
 262
 263         if (hook_head) {
 264                 struct nf_hook_state state;
 265
 266                 nf_hook_state_init(&state, hook, pf, indev, outdev,
 267                                    sk, net, okfn);
 268
 269                 ret = nf_hook_slow(skb, &state, hook_head, 0);
 270         }
 271         rcu_read_unlock();
 272
 273         return ret;
 274 }
 275
 276 /* Activate hook; either okfn or kfree_skb called, unless a hook
 277    returns NF_STOLEN (in which case, it's up to the hook to deal with
 278    the consequences).
 279
 280    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 281    accepted.
 282 */
 283
 284 /* RR:
 285    > I don't want nf_hook to return anything because people might forget
 286    > about async and trust the return value to mean "packet was ok".
 287
 288    AK:
 289    Just document it clearly, then you can expect some sense from kernel
 290    coders :)
 291 */
 292
 293 static inline int
 294 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 295              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 296              int (*okfn)(struct net *, struct sock *, struct sk_buff *),
 297              bool cond)
 298 {
 299         int ret;
 300
 301         if (!cond ||
 302             ((ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn)) == 1))
 303                 ret = okfn(net, sk, skb);
 304         return ret;
 305 }
 306
 307 static inline int
 308 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
 309         struct net_device *in, struct net_device *out,
 310         int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 311 {
 312         int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
 313         if (ret == 1)
 314                 ret = okfn(net, sk, skb);
 315         return ret;
 316 }
 317
 318 static inline void
 319 NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 320              struct list_head *head, struct net_device *in, struct net_device *out,
 321              int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 322 {
 323         struct nf_hook_entries *hook_head = NULL;
 324
 325 #ifdef CONFIG_JUMP_LABEL
 326         if (__builtin_constant_p(pf) &&
 327             __builtin_constant_p(hook) &&
 328             !static_key_false(&nf_hooks_needed[pf][hook]))
 329                 return;
 330 #endif
 331
 332         rcu_read_lock();
 333         switch (pf) {
 334         case NFPROTO_IPV4:
 335                 hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
 336                 break;
 337         case NFPROTO_IPV6:
 338                 hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
 339                 break;
 340         default:
 341                 WARN_ON_ONCE(1);
 342                 break;
 343         }
 344
 345         if (hook_head) {
 346                 struct nf_hook_state state;
 347
 348                 nf_hook_state_init(&state, hook, pf, in, out, sk, net, okfn);
 349
 350                 nf_hook_slow_list(head, &state, hook_head);
 351         }
 352         rcu_read_unlock();
 353 }
 354
 355 /* Call setsockopt() */
 356 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, sockptr_t opt,
 357                   unsigned int len);
 358 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 359                   int *len);
 360
 361 struct flowi;
 362 struct nf_queue_entry;
 363
 364 __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
 365                     unsigned int dataoff, u_int8_t protocol,
 366                     unsigned short family);
 367
 368 __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 369                             unsigned int dataoff, unsigned int len,
 370                             u_int8_t protocol, unsigned short family);
 371 int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
 372              bool strict, unsigned short family);
 373
 374 #include <net/flow.h>
 375
 376 struct nf_conn;
 377 enum nf_nat_manip_type;
 378 struct nlattr;
 379
 380 struct nf_nat_hook {
 381         int (*parse_nat_setup)(struct nf_conn *ct, enum nf_nat_manip_type manip,
 382                                const struct nlattr *attr);
 383         void (*decode_session)(struct sk_buff *skb, struct flowi *fl);
 384         void (*remove_nat_bysrc)(struct nf_conn *ct);
 385 };
 386
 387 extern const struct nf_nat_hook __rcu *nf_nat_hook;
 388
 389 static inline void
 390 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 391 {
 392 #if IS_ENABLED(CONFIG_NF_NAT)
 393         const struct nf_nat_hook *nat_hook;
 394
 395         rcu_read_lock();
 396         nat_hook = rcu_dereference(nf_nat_hook);
 397         if (nat_hook && nat_hook->decode_session)
 398                 nat_hook->decode_session(skb, fl);
 399         rcu_read_unlock();
 400 #endif
 401 }
 402
 403 #else /* !CONFIG_NETFILTER */
 404 static inline int
 405 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 406              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 407              int (*okfn)(struct net *, struct sock *, struct sk_buff *),
 408              bool cond)
 409 {
 410         return okfn(net, sk, skb);
 411 }
 412
 413 static inline int
 414 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 415         struct sk_buff *skb, struct net_device *in, struct net_device *out,
 416         int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 417 {
 418         return okfn(net, sk, skb);
 419 }
 420
 421 static inline void
 422 NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 423              struct list_head *head, struct net_device *in, struct net_device *out,
 424              int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 425 {
 426         /* nothing to do */
 427 }
 428
 429 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 430                           struct sock *sk, struct sk_buff *skb,
 431                           struct net_device *indev, struct net_device *outdev,
 432                           int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 433 {
 434         return 1;
 435 }
 436 struct flowi;
 437 static inline void
 438 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 439 {
 440 }
 441 #endif /*CONFIG_NETFILTER*/
 442
 443 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 444 #include <linux/netfilter/nf_conntrack_zones_common.h>
 445
 446 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 447 void nf_ct_set_closing(struct nf_conntrack *nfct);
 448 struct nf_conntrack_tuple;
 449 bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
 450                          const struct sk_buff *skb);
 451 #else
 452 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 453 static inline void nf_ct_set_closing(struct nf_conntrack *nfct) {}
 454 struct nf_conntrack_tuple;
 455 static inline bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
 456                                        const struct sk_buff *skb)
 457 {
 458         return false;
 459 }
 460 #endif
 461
 462 struct nf_conn;
 463 enum ip_conntrack_info;
 464
 465 struct nf_ct_hook {
 466         int (*update)(struct net *net, struct sk_buff *skb);
 467         void (*destroy)(struct nf_conntrack *);
 468         bool (*get_tuple_skb)(struct nf_conntrack_tuple *,
 469                               const struct sk_buff *);
 470         void (*attach)(struct sk_buff *nskb, const struct sk_buff *skb);
 471         void (*set_closing)(struct nf_conntrack *nfct);
 472         int (*confirm)(struct sk_buff *skb);
 473 };
 474 extern const struct nf_ct_hook __rcu *nf_ct_hook;
 475
 476 struct nlattr;
 477
 478 struct nfnl_ct_hook {
 479         size_t (*build_size)(const struct nf_conn *ct);
 480         int (*build)(struct sk_buff *skb, struct nf_conn *ct,
 481                      enum ip_conntrack_info ctinfo,
 482                      u_int16_t ct_attr, u_int16_t ct_info_attr);
 483         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 484         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 485                              u32 portid, u32 report);
 486         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 487                            enum ip_conntrack_info ctinfo, s32 off);
 488 };
 489 extern const struct nfnl_ct_hook __rcu *nfnl_ct_hook;
 490
 491 struct nf_defrag_hook {
 492         struct module *owner;
 493         int (*enable)(struct net *net);
 494         void (*disable)(struct net *net);
 495 };
 496
 497 extern const struct nf_defrag_hook __rcu *nf_defrag_v4_hook;
 498 extern const struct nf_defrag_hook __rcu *nf_defrag_v6_hook;
 499
 500 /*
 501  * nf_skb_duplicated - TEE target has sent a packet
 502  *
 503  * When a xtables target sends a packet, the OUTPUT and POSTROUTING
 504  * hooks are traversed again, i.e. nft and xtables are invoked recursively.
 505  *
 506  * This is used by xtables TEE target to prevent the duplicated skb from
 507  * being duplicated again.
 508  */
 509 DECLARE_PER_CPU(bool, nf_skb_duplicated);
 510
 511 /*
 512  * Contains bitmask of ctnetlink event subscribers, if any.
 513  * Can't be pernet due to NETLINK_LISTEN_ALL_NSID setsockopt flag.
 514  */
 515 extern u8 nf_ctnetlink_has_listener;
 516 #endif /*__LINUX_NETFILTER_H*/