include/net/netfilter/nf_conntrack.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Connection state tracking for netfilter.  This is separated from,
   4  * but required by, the (future) NAT layer; it can also be used by an iptables
   5  * extension.
   6  *
   7  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   8  *      - generalize L3 protocol dependent part.
   9  *
  10  * Derived from include/linux/netfiter_ipv4/ip_conntrack.h
  11  */
  12
  13 #ifndef _NF_CONNTRACK_H
  14 #define _NF_CONNTRACK_H
  15
  16 #include <linux/netfilter/nf_conntrack_common.h>
  17
  18 #include <linux/bitops.h>
  19 #include <linux/compiler.h>
  20 #include <linux/atomic.h>
  21
  22 #include <linux/netfilter/nf_conntrack_tcp.h>
  23 #include <linux/netfilter/nf_conntrack_dccp.h>
  24 #include <linux/netfilter/nf_conntrack_sctp.h>
  25 #include <linux/netfilter/nf_conntrack_proto_gre.h>
  26 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  27
  28 #include <net/netfilter/nf_conntrack_tuple.h>
  29
  30 /* per conntrack: protocol private data */
  31 union nf_conntrack_proto {
  32         /* insert conntrack proto private data here */
  33         struct nf_ct_dccp dccp;
  34         struct ip_ct_sctp sctp;
  35         struct ip_ct_tcp tcp;
  36         struct nf_ct_gre gre;
  37         unsigned int tmpl_padto;
  38 };
  39
  40 union nf_conntrack_expect_proto {
  41         /* insert expect proto private data here */
  42 };
  43
  44 #include <linux/types.h>
  45 #include <linux/skbuff.h>
  46
  47 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  48 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  49
  50 struct nf_conn {
  51         /* Usage count in here is 1 for hash table, 1 per skb,
  52          * plus 1 for any connection(s) we are `master' for
  53          *
  54          * Hint, SKB address this struct and refcnt via skb->_nfct and
  55          * helpers nf_conntrack_get() and nf_conntrack_put().
  56          * Helper nf_ct_put() equals nf_conntrack_put() by dec refcnt,
  57          * beware nf_ct_get() is different and don't inc refcnt.
  58          */
  59         struct nf_conntrack ct_general;
  60
  61         spinlock_t      lock;
  62         u16             cpu;
  63
  64 #ifdef CONFIG_NF_CONNTRACK_ZONES
  65         struct nf_conntrack_zone zone;
  66 #endif
  67         /* XXX should I move this to the tail ? - Y.K */
  68         /* These are my tuples; original and reply */
  69         struct nf_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];
  70
  71         /* Have we seen traffic both ways yet? (bitset) */
  72         unsigned long status;
  73
  74         /* jiffies32 when this ct is considered dead */
  75         u32 timeout;
  76
  77         possible_net_t ct_net;
  78
  79 #if IS_ENABLED(CONFIG_NF_NAT)
  80         struct hlist_node       nat_bysource;
  81 #endif
  82         /* all members below initialized via memset */
  83         u8 __nfct_init_offset[0];
  84
  85         /* If we were expected by an expectation, this will be it */
  86         struct nf_conn *master;
  87
  88 #if defined(CONFIG_NF_CONNTRACK_MARK)
  89         u_int32_t mark;
  90 #endif
  91
  92 #ifdef CONFIG_NF_CONNTRACK_SECMARK
  93         u_int32_t secmark;
  94 #endif
  95
  96         /* Extensions */
  97         struct nf_ct_ext *ext;
  98
  99 #if defined(CONFIG_NETFILTER_XT_MATCH_LAYER7) || \
 100     defined(CONFIG_NETFILTER_XT_MATCH_LAYER7_MODULE)
 101         struct {
 102                 /*
 103                  * e.g. "http". NULL before decision. "unknown" after decision
 104                  * if no match.
 105                  */
 106                 char *app_proto;
 107                 /*
 108                  * application layer data so far. NULL after match decision.
 109                  */
 110                 char *app_data;
 111                 unsigned int app_data_len;
 112         } layer7;
 113 #endif
 114
 115         /* Storage reserved for other modules, must be the last member */
 116         union nf_conntrack_proto proto;
 117 };
 118
 119 static inline struct nf_conn *
 120 nf_ct_tuplehash_to_ctrack(const struct nf_conntrack_tuple_hash *hash)
 121 {
 122         return container_of(hash, struct nf_conn,
 123                             tuplehash[hash->tuple.dst.dir]);
 124 }
 125
 126 static inline u_int16_t nf_ct_l3num(const struct nf_conn *ct)
 127 {
 128         return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
 129 }
 130
 131 static inline u_int8_t nf_ct_protonum(const struct nf_conn *ct)
 132 {
 133         return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum;
 134 }
 135
 136 #define nf_ct_tuple(ct, dir) (&(ct)->tuplehash[dir].tuple)
 137
 138 /* get master conntrack via master expectation */
 139 #define master_ct(conntr) (conntr->master)
 140
 141 extern struct net init_net;
 142
 143 static inline struct net *nf_ct_net(const struct nf_conn *ct)
 144 {
 145         return read_pnet(&ct->ct_net);
 146 }
 147
 148 /* Alter reply tuple (maybe alter helper). */
 149 void nf_conntrack_alter_reply(struct nf_conn *ct,
 150                               const struct nf_conntrack_tuple *newreply);
 151
 152 /* Is this tuple taken? (ignoring any belonging to the given
 153    conntrack). */
 154 int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 155                              const struct nf_conn *ignored_conntrack);
 156
 157 #define NFCT_INFOMASK   7UL
 158 #define NFCT_PTRMASK    ~(NFCT_INFOMASK)
 159
 160 /* Return conntrack_info and tuple hash for given skb. */
 161 static inline struct nf_conn *
 162 nf_ct_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
 163 {
 164         *ctinfo = skb->_nfct & NFCT_INFOMASK;
 165
 166         return (struct nf_conn *)(skb->_nfct & NFCT_PTRMASK);
 167 }
 168
 169 /* decrement reference count on a conntrack */
 170 static inline void nf_ct_put(struct nf_conn *ct)
 171 {
 172         WARN_ON(!ct);
 173         nf_conntrack_put(&ct->ct_general);
 174 }
 175
 176 /* Protocol module loading */
 177 int nf_ct_l3proto_try_module_get(unsigned short l3proto);
 178 void nf_ct_l3proto_module_put(unsigned short l3proto);
 179
 180 /* load module; enable/disable conntrack in this namespace */
 181 int nf_ct_netns_get(struct net *net, u8 nfproto);
 182 void nf_ct_netns_put(struct net *net, u8 nfproto);
 183
 184 /*
 185  * Allocate a hashtable of hlist_head (if nulls == 0),
 186  * or hlist_nulls_head (if nulls == 1)
 187  */
 188 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls);
 189
 190 void nf_ct_free_hashtable(void *hash, unsigned int size);
 191
 192 int nf_conntrack_hash_check_insert(struct nf_conn *ct);
 193 bool nf_ct_delete(struct nf_conn *ct, u32 pid, int report);
 194
 195 bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 196                        u_int16_t l3num, struct net *net,
 197                        struct nf_conntrack_tuple *tuple);
 198 bool nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
 199                           const struct nf_conntrack_tuple *orig);
 200
 201 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 202                           const struct sk_buff *skb,
 203                           unsigned long extra_jiffies, int do_acct);
 204
 205 /* Refresh conntrack for this many jiffies and do accounting */
 206 static inline void nf_ct_refresh_acct(struct nf_conn *ct,
 207                                       enum ip_conntrack_info ctinfo,
 208                                       const struct sk_buff *skb,
 209                                       unsigned long extra_jiffies)
 210 {
 211         __nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, 1);
 212 }
 213
 214 /* Refresh conntrack for this many jiffies */
 215 static inline void nf_ct_refresh(struct nf_conn *ct,
 216                                  const struct sk_buff *skb,
 217                                  unsigned long extra_jiffies)
 218 {
 219         __nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, 0);
 220 }
 221
 222 /* kill conntrack and do accounting */
 223 bool nf_ct_kill_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 224                      const struct sk_buff *skb);
 225
 226 /* kill conntrack without accounting */
 227 static inline bool nf_ct_kill(struct nf_conn *ct)
 228 {
 229         return nf_ct_delete(ct, 0, 0);
 230 }
 231
 232 /* These are for NAT.  Icky. */
 233 extern s32 (*nf_ct_nat_offset)(const struct nf_conn *ct,
 234                                enum ip_conntrack_dir dir,
 235                                u32 seq);
 236
 237 /* Set all unconfirmed conntrack as dying */
 238 void nf_ct_unconfirmed_destroy(struct net *);
 239
 240 /* Iterate over all conntracks: if iter returns true, it's deleted. */
 241 void nf_ct_iterate_cleanup_net(struct net *net,
 242                                int (*iter)(struct nf_conn *i, void *data),
 243                                void *data, u32 portid, int report);
 244
 245 /* also set unconfirmed conntracks as dying. Only use in module exit path. */
 246 void nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data),
 247                            void *data);
 248
 249 struct nf_conntrack_zone;
 250
 251 void nf_conntrack_free(struct nf_conn *ct);
 252 struct nf_conn *nf_conntrack_alloc(struct net *net,
 253                                    const struct nf_conntrack_zone *zone,
 254                                    const struct nf_conntrack_tuple *orig,
 255                                    const struct nf_conntrack_tuple *repl,
 256                                    gfp_t gfp);
 257
 258 static inline int nf_ct_is_template(const struct nf_conn *ct)
 259 {
 260         return test_bit(IPS_TEMPLATE_BIT, &ct->status);
 261 }
 262
 263 /* It's confirmed if it is, or has been in the hash table. */
 264 static inline int nf_ct_is_confirmed(const struct nf_conn *ct)
 265 {
 266         return test_bit(IPS_CONFIRMED_BIT, &ct->status);
 267 }
 268
 269 static inline int nf_ct_is_dying(const struct nf_conn *ct)
 270 {
 271         return test_bit(IPS_DYING_BIT, &ct->status);
 272 }
 273
 274 /* Packet is received from loopback */
 275 static inline bool nf_is_loopback_packet(const struct sk_buff *skb)
 276 {
 277         return skb->dev && skb->skb_iif && skb->dev->flags & IFF_LOOPBACK;
 278 }
 279
 280 #define nfct_time_stamp ((u32)(jiffies))
 281
 282 /* jiffies until ct expires, 0 if already expired */
 283 static inline unsigned long nf_ct_expires(const struct nf_conn *ct)
 284 {
 285         s32 timeout = ct->timeout - nfct_time_stamp;
 286
 287         return timeout > 0 ? timeout : 0;
 288 }
 289
 290 static inline bool nf_ct_is_expired(const struct nf_conn *ct)
 291 {
 292         return (__s32)(ct->timeout - nfct_time_stamp) <= 0;
 293 }
 294
 295 /* use after obtaining a reference count */
 296 static inline bool nf_ct_should_gc(const struct nf_conn *ct)
 297 {
 298         return nf_ct_is_expired(ct) && nf_ct_is_confirmed(ct) &&
 299                !nf_ct_is_dying(ct);
 300 }
 301
 302 struct kernel_param;
 303
 304 int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp);
 305 int nf_conntrack_hash_resize(unsigned int hashsize);
 306
 307 extern struct hlist_nulls_head *nf_conntrack_hash;
 308 extern unsigned int nf_conntrack_htable_size;
 309 extern seqcount_t nf_conntrack_generation;
 310 extern unsigned int nf_conntrack_max;
 311
 312 /* must be called with rcu read lock held */
 313 static inline void
 314 nf_conntrack_get_ht(struct hlist_nulls_head **hash, unsigned int *hsize)
 315 {
 316         struct hlist_nulls_head *hptr;
 317         unsigned int sequence, hsz;
 318
 319         do {
 320                 sequence = read_seqcount_begin(&nf_conntrack_generation);
 321                 hsz = nf_conntrack_htable_size;
 322                 hptr = nf_conntrack_hash;
 323         } while (read_seqcount_retry(&nf_conntrack_generation, sequence));
 324
 325         *hash = hptr;
 326         *hsize = hsz;
 327 }
 328
 329 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
 330                                  const struct nf_conntrack_zone *zone,
 331                                  gfp_t flags);
 332 void nf_ct_tmpl_free(struct nf_conn *tmpl);
 333
 334 static inline void
 335 nf_ct_set(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info info)
 336 {
 337         skb->_nfct = (unsigned long)ct | info;
 338 }
 339
 340 #define NF_CT_STAT_INC(net, count)        __this_cpu_inc((net)->ct.stat->count)
 341 #define NF_CT_STAT_INC_ATOMIC(net, count) this_cpu_inc((net)->ct.stat->count)
 342 #define NF_CT_STAT_ADD_ATOMIC(net, count, v) this_cpu_add((net)->ct.stat->count, (v))
 343
 344 #define MODULE_ALIAS_NFCT_HELPER(helper) \
 345         MODULE_ALIAS("nfct-helper-" helper)
 346
 347 #endif /* _NF_CONNTRACK_H */