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