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 {
  81         u16                             num_hook_entries;
  82         /* padding */
  83         struct nf_hook_entry            hooks[];
  84
  85         /* trailer: pointers to original orig_ops of each hook.
  86          *
  87          * This is not part of struct nf_hook_entry since its only
  88          * needed in slow path (hook register/unregister).
  89          *
  90          * const struct nf_hook_ops     *orig_ops[]
  91          */
  92 };
  93
  94 static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
  95 {
  96         unsigned int n = e->num_hook_entries;
  97         const void *hook_end;
  98
  99         hook_end = &e->hooks[n]; /* this is *past* ->hooks[]! */
 100
 101         return (struct nf_hook_ops **)hook_end;
 102 }
 103
 104 static inline int
 105 nf_hook_entry_hookfn(const struct nf_hook_entry *entry, struct sk_buff *skb,
 106                      struct nf_hook_state *state)
 107 {
 108         return entry->hook(entry->priv, skb, state);
 109 }
 110
 111 static inline void nf_hook_state_init(struct nf_hook_state *p,
 112                                       unsigned int hook,
 113                                       u_int8_t pf,
 114                                       struct net_device *indev,
 115                                       struct net_device *outdev,
 116                                       struct sock *sk,
 117                                       struct net *net,
 118                                       int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 119 {
 120         p->hook = hook;
 121         p->pf = pf;
 122         p->in = indev;
 123         p->out = outdev;
 124         p->sk = sk;
 125         p->net = net;
 126         p->okfn = okfn;
 127 }
 128
 129
 130
 131 struct nf_sockopt_ops {
 132         struct list_head list;
 133
 134         u_int8_t pf;
 135
 136         /* Non-inclusive ranges: use 0/0/NULL to never get called. */
 137         int set_optmin;
 138         int set_optmax;
 139         int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 140 #ifdef CONFIG_COMPAT
 141         int (*compat_set)(struct sock *sk, int optval,
 142                         void __user *user, unsigned int len);
 143 #endif
 144         int get_optmin;
 145         int get_optmax;
 146         int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 147 #ifdef CONFIG_COMPAT
 148         int (*compat_get)(struct sock *sk, int optval,
 149                         void __user *user, int *len);
 150 #endif
 151         /* Use the module struct to lock set/get code in place */
 152         struct module *owner;
 153 };
 154
 155 /* Function to register/unregister hook points. */
 156 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
 157 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
 158 int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 159                           unsigned int n);
 160 void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 161                              unsigned int n);
 162
 163 /* Functions to register get/setsockopt ranges (non-inclusive).  You
 164    need to check permissions yourself! */
 165 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 166 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 167
 168 #ifdef HAVE_JUMP_LABEL
 169 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 170 #endif
 171
 172 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
 173                  const struct nf_hook_entries *e, unsigned int i);
 174
 175 /**
 176  *      nf_hook - call a netfilter hook
 177  *
 178  *      Returns 1 if the hook has allowed the packet to pass.  The function
 179  *      okfn must be invoked by the caller in this case.  Any other return
 180  *      value indicates the packet has been consumed by the hook.
 181  */
 182 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 183                           struct sock *sk, struct sk_buff *skb,
 184                           struct net_device *indev, struct net_device *outdev,
 185                           int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 186 {
 187         struct nf_hook_entries *hook_head;
 188         int ret = 1;
 189
 190 #ifdef HAVE_JUMP_LABEL
 191         if (__builtin_constant_p(pf) &&
 192             __builtin_constant_p(hook) &&
 193             !static_key_false(&nf_hooks_needed[pf][hook]))
 194                 return 1;
 195 #endif
 196
 197         rcu_read_lock();
 198         hook_head = rcu_dereference(net->nf.hooks[pf][hook]);
 199         if (hook_head) {
 200                 struct nf_hook_state state;
 201
 202                 nf_hook_state_init(&state, hook, pf, indev, outdev,
 203                                    sk, net, okfn);
 204
 205                 ret = nf_hook_slow(skb, &state, hook_head, 0);
 206         }
 207         rcu_read_unlock();
 208
 209         return ret;
 210 }
 211
 212 /* Activate hook; either okfn or kfree_skb called, unless a hook
 213    returns NF_STOLEN (in which case, it's up to the hook to deal with
 214    the consequences).
 215
 216    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
 217    accepted.
 218 */
 219
 220 /* RR:
 221    > I don't want nf_hook to return anything because people might forget
 222    > about async and trust the return value to mean "packet was ok".
 223
 224    AK:
 225    Just document it clearly, then you can expect some sense from kernel
 226    coders :)
 227 */
 228
 229 static inline int
 230 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 231              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 232              int (*okfn)(struct net *, struct sock *, struct sk_buff *),
 233              bool cond)
 234 {
 235         int ret;
 236
 237         if (!cond ||
 238             ((ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn)) == 1))
 239                 ret = okfn(net, sk, skb);
 240         return ret;
 241 }
 242
 243 static inline int
 244 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
 245         struct net_device *in, struct net_device *out,
 246         int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 247 {
 248         int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
 249         if (ret == 1)
 250                 ret = okfn(net, sk, skb);
 251         return ret;
 252 }
 253
 254 /* Call setsockopt() */
 255 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 256                   unsigned int len);
 257 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 258                   int *len);
 259 #ifdef CONFIG_COMPAT
 260 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 261                 char __user *opt, unsigned int len);
 262 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 263                 char __user *opt, int *len);
 264 #endif
 265
 266 /* Call this before modifying an existing packet: ensures it is
 267    modifiable and linear to the point you care about (writable_len).
 268    Returns true or false. */
 269 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 270
 271 struct flowi;
 272 struct nf_queue_entry;
 273
 274 struct nf_afinfo {
 275         unsigned short  family;
 276         __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
 277                                     unsigned int dataoff, u_int8_t protocol);
 278         __sum16         (*checksum_partial)(struct sk_buff *skb,
 279                                             unsigned int hook,
 280                                             unsigned int dataoff,
 281                                             unsigned int len,
 282                                             u_int8_t protocol);
 283         int             (*route)(struct net *net, struct dst_entry **dst,
 284                                  struct flowi *fl, bool strict);
 285         void            (*saveroute)(const struct sk_buff *skb,
 286                                      struct nf_queue_entry *entry);
 287         int             (*reroute)(struct net *net, struct sk_buff *skb,
 288                                    const struct nf_queue_entry *entry);
 289         int             route_key_size;
 290 };
 291
 292 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 293 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 294 {
 295         return rcu_dereference(nf_afinfo[family]);
 296 }
 297
 298 static inline __sum16
 299 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 300             u_int8_t protocol, unsigned short family)
 301 {
 302         const struct nf_afinfo *afinfo;
 303         __sum16 csum = 0;
 304
 305         rcu_read_lock();
 306         afinfo = nf_get_afinfo(family);
 307         if (afinfo)
 308                 csum = afinfo->checksum(skb, hook, dataoff, protocol);
 309         rcu_read_unlock();
 310         return csum;
 311 }
 312
 313 static inline __sum16
 314 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 315                     unsigned int dataoff, unsigned int len,
 316                     u_int8_t protocol, unsigned short family)
 317 {
 318         const struct nf_afinfo *afinfo;
 319         __sum16 csum = 0;
 320
 321         rcu_read_lock();
 322         afinfo = nf_get_afinfo(family);
 323         if (afinfo)
 324                 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 325                                                 protocol);
 326         rcu_read_unlock();
 327         return csum;
 328 }
 329
 330 int nf_register_afinfo(const struct nf_afinfo *afinfo);
 331 void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
 332
 333 #include <net/flow.h>
 334 extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 335
 336 static inline void
 337 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 338 {
 339 #ifdef CONFIG_NF_NAT_NEEDED
 340         void (*decodefn)(struct sk_buff *, struct flowi *);
 341
 342         rcu_read_lock();
 343         decodefn = rcu_dereference(nf_nat_decode_session_hook);
 344         if (decodefn)
 345                 decodefn(skb, fl);
 346         rcu_read_unlock();
 347 #endif
 348 }
 349
 350 #else /* !CONFIG_NETFILTER */
 351 static inline int
 352 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 353              struct sk_buff *skb, struct net_device *in, struct net_device *out,
 354              int (*okfn)(struct net *, struct sock *, struct sk_buff *),
 355              bool cond)
 356 {
 357         return okfn(net, sk, skb);
 358 }
 359
 360 static inline int
 361 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 362         struct sk_buff *skb, struct net_device *in, struct net_device *out,
 363         int (*okfn)(struct net *, struct sock *, struct sk_buff *))
 364 {
 365         return okfn(net, sk, skb);
 366 }
 367
 368 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 369                           struct sock *sk, struct sk_buff *skb,
 370                           struct net_device *indev, struct net_device *outdev,
 371                           int (*okfn)(struct net *, struct sock *, 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 #include <linux/netfilter/nf_conntrack_zones_common.h>
 384
 385 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 386 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 387 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
 388 #else
 389 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 390 #endif
 391
 392 struct nf_conn;
 393 enum ip_conntrack_info;
 394 struct nlattr;
 395
 396 struct nfnl_ct_hook {
 397         struct nf_conn *(*get_ct)(const struct sk_buff *skb,
 398                                   enum ip_conntrack_info *ctinfo);
 399         size_t (*build_size)(const struct nf_conn *ct);
 400         int (*build)(struct sk_buff *skb, struct nf_conn *ct,
 401                      enum ip_conntrack_info ctinfo,
 402                      u_int16_t ct_attr, u_int16_t ct_info_attr);
 403         int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 404         int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
 405                              u32 portid, u32 report);
 406         void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 407                            enum ip_conntrack_info ctinfo, s32 off);
 408 };
 409 extern struct nfnl_ct_hook __rcu *nfnl_ct_hook;
 410
 411 /**
 412  * nf_skb_duplicated - TEE target has sent a packet
 413  *
 414  * When a xtables target sends a packet, the OUTPUT and POSTROUTING
 415  * hooks are traversed again, i.e. nft and xtables are invoked recursively.
 416  *
 417  * This is used by xtables TEE target to prevent the duplicated skb from
 418  * being duplicated again.
 419  */
 420 DECLARE_PER_CPU(bool, nf_skb_duplicated);
 421
 422 #endif /*__LINUX_NETFILTER_H*/