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         bool                    nat_hook;
  71         unsigned int            hooknum;
  72         /* Hooks are ordered in ascending priority. */
  73         int                     priority;
  74 };
  75
  76 struct nf_hook_entry {
  77         nf_hookfn                       *hook;
  78         void                            *priv;
  79 };
  80
  81 struct nf_hook_entries_rcu_head {
  82         struct rcu_head head;
  83         void    *allocation;
  84 };
  85
  86 struct nf_hook_entries {
  87         u16                             num_hook_entries;
  88         /* padding */
  89         struct nf_hook_entry            hooks[];
  90
  91         /* trailer: pointers to original orig_ops of each hook,
  92          * followed by rcu_head and scratch space used for freeing
  93          * the structure via call_rcu.
  94          *
  95          *   This is not part of struct nf_hook_entry since its only
  96          *   needed in slow path (hook register/unregister):
  97          * const struct nf_hook_ops     *orig_ops[]
  98          *
  99          *   For the same reason, we store this at end -- its
 100          *   only needed when a hook is deleted, not during
 101          *   packet path processing:
 102          * struct nf_hook_entries_rcu_head     head
 103          */
 104 };
 105
 106 static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
 107 {
 108         unsigned int n = e->num_hook_entries;
 109         const void *hook_end;
 110
 111         hook_end = &e->hooks[n]; /* this is *past* ->hooks[]! */
 112
 113         return (struct nf_hook_ops **)hook_end;
 114 }
 115
 116 static inline int
 117 nf_hook_entry_hookfn(const struct nf_hook_entry *entry, struct sk_buff *skb,
 118                      struct nf_hook_state *state)
 119 {
 120         return entry->hook(entry->priv, skb, state);
 121 }
 122
 123 static inline void nf_hook_state_init(struct nf_hook_state *p,
 124                                       unsigned int hook,
 125                                       u_int8_t pf,
 126                                       struct net_device *indev,
 127                                       struct net_device *outdev,
 128                                       struct sock *sk,
 129                                       struct net *net,
 130                                       int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 131 {
 132         p->hook = hook;
 133         p->pf = pf;
 134         p->in = indev;
 135         p->out = outdev;
 136         p->sk = sk;
 137         p->net = net;
 138         p->okfn = okfn;
 139 }
 140
 141
 142
 143 struct nf_sockopt_ops {
 144         struct list_head list;
 145
 146         u_int8_t pf;
 147
 148         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 149         int set_optmin;
 150         int set_optmax;
 151         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 152 #ifdef CONFIG_COMPAT
 153         int (*compat_set)(struct sock *sk, int optval,
 154                         void __user *user, unsigned int len);
 155 #endif
 156         int get_optmin;
 157         int get_optmax;
 158         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 159 #ifdef CONFIG_COMPAT
 160         int (*compat_get)(struct sock *sk, int optval,
 161                         void __user *user, int *len);
 162 #endif
 163         /* Use the module struct to lock set/get code in place */
 164         struct module *owner;
 165 };
 166
 167 /* Function to register/unregister hook points. */
 168 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
 169 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
 170 int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 171                           unsigned int n);
 172 void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 173                              unsigned int n);
 174
 175 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 176    need to check permissions yourself! */
 177 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 178 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 179
 180 #ifdef HAVE_JUMP_LABEL
 181 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 182 #endif
 183
 184 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
 185                  const struct nf_hook_entries *e, unsigned int i);
 186
 187 /**
 188  *      nf_hook - call a netfilter hook
 189  *
 190  *      Returns 1 if the hook has allowed the packet to pass.  The function
 191  *      okfn must be invoked by the caller in this case.  Any other return
 192  *      value indicates the packet has been consumed by the hook.
 193  */
 194 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 195                           struct sock *sk, struct sk_buff *skb,
 196                           struct net_device *indev, struct net_device *outdev,
 197                           int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 198 {
 199         struct nf_hook_entries *hook_head = NULL;
 200         int ret = 1;
 201
 202 #ifdef HAVE_JUMP_LABEL
 203         if (__builtin_constant_p(pf) &&
 204             __builtin_constant_p(hook) &&
 205             !static_key_false(&nf_hooks_needed[pf][hook]))
 206                 return 1;
 207 #endif
 208
 209         rcu_read_lock();
 210         switch (pf) {
 211         case NFPROTO_IPV4:
 212                 hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
 213                 break;
 214         case NFPROTO_IPV6:
 215                 hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
 216                 break;
 217         case NFPROTO_ARP:
 218 #ifdef CONFIG_NETFILTER_FAMILY_ARP
 219                 hook_head = rcu_dereference(net->nf.hooks_arp[hook]);
 220 #endif
 221                 break;
 222         case NFPROTO_BRIDGE:
 223 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 224                 hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
 225 #endif
 226                 break;
 227 #if IS_ENABLED(CONFIG_DECNET)
 228         case NFPROTO_DECNET:
 229                 hook_head = rcu_dereference(net->nf.hooks_decnet[hook]);
 230                 break;
 231 #endif
 232         default:
 233                 WARN_ON_ONCE(1);
 234                 break;
 235         }
 236
 237         if (hook_head) {
 238                 struct nf_hook_state state;
 239
 240                 nf_hook_state_init(&state, hook, pf, indev, outdev,
 241                                    sk, net, okfn);
 242
 243                 ret = nf_hook_slow(skb, &state, hook_head, 0);
 244         }
 245         rcu_read_unlock();
 246
 247         return ret;
 248 }
 249
 250 /* Activate hook; either okfn or kfree_skb called, unless a hook
 251    returns NF_STOLEN (in which case, it's up to the hook to deal with
 252    the consequences).
 253
 254    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 255    accepted.
 256 */
 257
 258 /* RR:
 259    > I don't want nf_hook to return anything because people might forget
 260    > about async and trust the return value to mean "packet was ok".
 261
 262    AK:
 263    Just document it clearly, then you can expect some sense from kernel
 264    coders :)
 265 */
 266
 267 static inline int
 268 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 269              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 270              int (*okfn)(struct net *, struct sock *, struct sk_buff *),
 271              bool cond)
 272 {
 273         int ret;
 274
 275         if (!cond ||
 276             ((ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn)) == 1))
 277                 ret = okfn(net, sk, skb);
 278         return ret;
 279 }
 280
 281 static inline int
 282 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
 283         struct net_device *in, struct net_device *out,
 284         int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 285 {
 286         int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
 287         if (ret == 1)
 288                 ret = okfn(net, sk, skb);
 289         return ret;
 290 }
 291
 292 /* Call setsockopt() */
 293 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 294                   unsigned int len);
 295 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 296                   int *len);
 297 #ifdef CONFIG_COMPAT
 298 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 299                 char __user *opt, unsigned int len);
 300 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 301                 char __user *opt, int *len);
 302 #endif
 303
 304 /* Call this before modifying an existing packet: ensures it is
 305    modifiable and linear to the point you care about (writable_len).
 306    Returns true or false. */
 307 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 308
 309 struct flowi;
 310 struct nf_queue_entry;
 311
 312 __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
 313                     unsigned int dataoff, u_int8_t protocol,
 314                     unsigned short family);
 315
 316 __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 317                             unsigned int dataoff, unsigned int len,
 318                             u_int8_t protocol, unsigned short family);
 319 int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
 320              bool strict, unsigned short family);
 321 int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry);
 322
 323 #include <net/flow.h>
 324 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 325
 326 static inline void
 327 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 328 {
 329 #ifdef CONFIG_NF_NAT_NEEDED
 330         void (*decodefn)(struct sk_buff *, struct flowi *);
 331
 332         rcu_read_lock();
 333         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 334         if (decodefn)
 335                 decodefn(skb, fl);
 336         rcu_read_unlock();
 337 #endif
 338 }
 339
 340 #else /* !CONFIG_NETFILTER */
 341 static inline int
 342 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 343              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 344              int (*okfn)(struct net *, struct sock *, struct sk_buff *),
 345              bool cond)
 346 {
 347         return okfn(net, sk, skb);
 348 }
 349
 350 static inline int
 351 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 352         struct sk_buff *skb, struct net_device *in, struct net_device *out,
 353         int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 354 {
 355         return okfn(net, sk, skb);
 356 }
 357
 358 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 359                           struct sock *sk, struct sk_buff *skb,
 360                           struct net_device *indev, struct net_device *outdev,
 361                           int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 362 {
 363         return 1;
 364 }
 365 struct flowi;
 366 static inline void
 367 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 368 {
 369 }
 370 #endif /*CONFIG_NETFILTER*/
 371
 372 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 373 #include <linux/netfilter/nf_conntrack_zones_common.h>
 374
 375 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 376 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 377 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 378 #else
 379 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 380 #endif
 381
 382 struct nf_conn;
 383 enum ip_conntrack_info;
 384 struct nlattr;
 385
 386 struct nfnl_ct_hook {
 387         struct nf_conn *(*get_ct)(const struct sk_buff *skb,
 388                                   enum ip_conntrack_info *ctinfo);
 389         size_t (*build_size)(const struct nf_conn *ct);
 390         int (*build)(struct sk_buff *skb, struct nf_conn *ct,
 391                      enum ip_conntrack_info ctinfo,
 392                      u_int16_t ct_attr, u_int16_t ct_info_attr);
 393         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 394         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 395                              u32 portid, u32 report);
 396         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 397                            enum ip_conntrack_info ctinfo, s32 off);
 398 };
 399 extern struct nfnl_ct_hook __rcu *nfnl_ct_hook;
 400
 401 /**
 402  * nf_skb_duplicated - TEE target has sent a packet
 403  *
 404  * When a xtables target sends a packet, the OUTPUT and POSTROUTING
 405  * hooks are traversed again, i.e. nft and xtables are invoked recursively.
 406  *
 407  * This is used by xtables TEE target to prevent the duplicated skb from
 408  * being duplicated again.
 409  */
 410 DECLARE_PER_CPU(bool, nf_skb_duplicated);
 411
 412 #endif /*__LINUX_NETFILTER_H*/