include/net/netfilter/nf_conntrack.h

   1 /*
   2  * Connection state tracking for netfilter.  This is separated from,
   3  * but required by, the (future) NAT layer; it can also be used by an iptables
   4  * extension.
   5  *
   6  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   7  *      - generalize L3 protocol dependent part.
   8  *
   9  * Derived from include/linux/netfiter_ipv4/ip_conntrack.h
  10  */
  11
  12 #ifndef _NF_CONNTRACK_H
  13 #define _NF_CONNTRACK_H
  14
  15 #include <linux/netfilter/nf_conntrack_common.h>
  16
  17 #include <linux/bitops.h>
  18 #include <linux/compiler.h>
  19 #include <linux/atomic.h>
  20 #include <linux/rhashtable.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 };
  38
  39 union nf_conntrack_expect_proto {
  40         /* insert expect proto private data here */
  41 };
  42
  43 #include <linux/types.h>
  44 #include <linux/skbuff.h>
  45
  46 #ifdef CONFIG_NETFILTER_DEBUG
  47 #define NF_CT_ASSERT(x)         WARN_ON(!(x))
  48 #else
  49 #define NF_CT_ASSERT(x)
  50 #endif
  51
  52 struct nf_conntrack_helper;
  53
  54 /* Must be kept in sync with the classes defined by helpers */
  55 #define NF_CT_MAX_EXPECT_CLASSES        4
  56
  57 /* nf_conn feature for connections that have a helper */
  58 struct nf_conn_help {
  59         /* Helper. if any */
  60         struct nf_conntrack_helper __rcu *helper;
  61
  62         struct hlist_head expectations;
  63
  64         /* Current number of expected connections */
  65         u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
  66
  67         /* private helper information. */
  68         char data[];
  69 };
  70
  71 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  72 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  73
  74 struct nf_conn {
  75         /* Usage count in here is 1 for hash table, 1 per skb,
  76          * plus 1 for any connection(s) we are `master' for
  77          *
  78          * Hint, SKB address this struct and refcnt via skb->nfct and
  79          * helpers nf_conntrack_get() and nf_conntrack_put().
  80          * Helper nf_ct_put() equals nf_conntrack_put() by dec refcnt,
  81          * beware nf_ct_get() is different and don't inc refcnt.
  82          */
  83         struct nf_conntrack ct_general;
  84
  85         spinlock_t      lock;
  86         u16             cpu;
  87
  88 #ifdef CONFIG_NF_CONNTRACK_ZONES
  89         struct nf_conntrack_zone zone;
  90 #endif
  91         /* XXX should I move this to the tail ? - Y.K */
  92         /* These are my tuples; original and reply */
  93         struct nf_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];
  94
  95         /* Have we seen traffic both ways yet? (bitset) */
  96         unsigned long status;
  97
  98         /* jiffies32 when this ct is considered dead */
  99         u32 timeout;
 100
 101         possible_net_t ct_net;
 102
 103         /* all members below initialized via memset */
 104         u8 __nfct_init_offset[0];
 105
 106         /* If we were expected by an expectation, this will be it */
 107         struct nf_conn *master;
 108
 109 #if defined(CONFIG_NF_CONNTRACK_MARK)
 110         u_int32_t mark;
 111 #endif
 112
 113 #ifdef CONFIG_NF_CONNTRACK_SECMARK
 114         u_int32_t secmark;
 115 #endif
 116
 117         /* Extensions */
 118         struct nf_ct_ext *ext;
 119
 120 #if IS_ENABLED(CONFIG_NF_NAT)
 121         struct rhash_head       nat_bysource;
 122 #endif
 123         /* Storage reserved for other modules, must be the last member */
 124         union nf_conntrack_proto proto;
 125 };
 126
 127 static inline struct nf_conn *
 128 nf_ct_tuplehash_to_ctrack(const struct nf_conntrack_tuple_hash *hash)
 129 {
 130         return container_of(hash, struct nf_conn,
 131                             tuplehash[hash->tuple.dst.dir]);
 132 }
 133
 134 static inline u_int16_t nf_ct_l3num(const struct nf_conn *ct)
 135 {
 136         return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
 137 }
 138
 139 static inline u_int8_t nf_ct_protonum(const struct nf_conn *ct)
 140 {
 141         return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum;
 142 }
 143
 144 #define nf_ct_tuple(ct, dir) (&(ct)->tuplehash[dir].tuple)
 145
 146 /* get master conntrack via master expectation */
 147 #define master_ct(conntr) (conntr->master)
 148
 149 extern struct net init_net;
 150
 151 static inline struct net *nf_ct_net(const struct nf_conn *ct)
 152 {
 153         return read_pnet(&ct->ct_net);
 154 }
 155
 156 /* Alter reply tuple (maybe alter helper). */
 157 void nf_conntrack_alter_reply(struct nf_conn *ct,
 158                               const struct nf_conntrack_tuple *newreply);
 159
 160 /* Is this tuple taken? (ignoring any belonging to the given
 161    conntrack). */
 162 int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 163                              const struct nf_conn *ignored_conntrack);
 164
 165 /* Return conntrack_info and tuple hash for given skb. */
 166 static inline struct nf_conn *
 167 nf_ct_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
 168 {
 169         *ctinfo = skb->nfctinfo;
 170         return (struct nf_conn *)skb->nfct;
 171 }
 172
 173 /* decrement reference count on a conntrack */
 174 static inline void nf_ct_put(struct nf_conn *ct)
 175 {
 176         NF_CT_ASSERT(ct);
 177         nf_conntrack_put(&ct->ct_general);
 178 }
 179
 180 /* Protocol module loading */
 181 int nf_ct_l3proto_try_module_get(unsigned short l3proto);
 182 void nf_ct_l3proto_module_put(unsigned short l3proto);
 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 /* Fake conntrack entry for untracked connections */
 238 DECLARE_PER_CPU(struct nf_conn, nf_conntrack_untracked);
 239 static inline struct nf_conn *nf_ct_untracked_get(void)
 240 {
 241         return raw_cpu_ptr(&nf_conntrack_untracked);
 242 }
 243 void nf_ct_untracked_status_or(unsigned long bits);
 244
 245 /* Iterate over all conntracks: if iter returns true, it's deleted. */
 246 void nf_ct_iterate_cleanup(struct net *net,
 247                            int (*iter)(struct nf_conn *i, void *data),
 248                            void *data, u32 portid, int report);
 249
 250 struct nf_conntrack_zone;
 251
 252 void nf_conntrack_free(struct nf_conn *ct);
 253 struct nf_conn *nf_conntrack_alloc(struct net *net,
 254                                    const struct nf_conntrack_zone *zone,
 255                                    const struct nf_conntrack_tuple *orig,
 256                                    const struct nf_conntrack_tuple *repl,
 257                                    gfp_t gfp);
 258
 259 static inline int nf_ct_is_template(const struct nf_conn *ct)
 260 {
 261         return test_bit(IPS_TEMPLATE_BIT, &ct->status);
 262 }
 263
 264 /* It's confirmed if it is, or has been in the hash table. */
 265 static inline int nf_ct_is_confirmed(const struct nf_conn *ct)
 266 {
 267         return test_bit(IPS_CONFIRMED_BIT, &ct->status);
 268 }
 269
 270 static inline int nf_ct_is_dying(const struct nf_conn *ct)
 271 {
 272         return test_bit(IPS_DYING_BIT, &ct->status);
 273 }
 274
 275 static inline int nf_ct_is_untracked(const struct nf_conn *ct)
 276 {
 277         return test_bit(IPS_UNTRACKED_BIT, &ct->status);
 278 }
 279
 280 /* Packet is received from loopback */
 281 static inline bool nf_is_loopback_packet(const struct sk_buff *skb)
 282 {
 283         return skb->dev && skb->skb_iif && skb->dev->flags & IFF_LOOPBACK;
 284 }
 285
 286 #define nfct_time_stamp ((u32)(jiffies))
 287
 288 /* jiffies until ct expires, 0 if already expired */
 289 static inline unsigned long nf_ct_expires(const struct nf_conn *ct)
 290 {
 291         s32 timeout = ct->timeout - nfct_time_stamp;
 292
 293         return timeout > 0 ? timeout : 0;
 294 }
 295
 296 static inline bool nf_ct_is_expired(const struct nf_conn *ct)
 297 {
 298         return (__s32)(ct->timeout - nfct_time_stamp) <= 0;
 299 }
 300
 301 /* use after obtaining a reference count */
 302 static inline bool nf_ct_should_gc(const struct nf_conn *ct)
 303 {
 304         return nf_ct_is_expired(ct) && nf_ct_is_confirmed(ct) &&
 305                !nf_ct_is_dying(ct);
 306 }
 307
 308 struct kernel_param;
 309
 310 int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp);
 311 int nf_conntrack_hash_resize(unsigned int hashsize);
 312
 313 extern struct hlist_nulls_head *nf_conntrack_hash;
 314 extern unsigned int nf_conntrack_htable_size;
 315 extern seqcount_t nf_conntrack_generation;
 316 extern unsigned int nf_conntrack_max;
 317
 318 /* must be called with rcu read lock held */
 319 static inline void
 320 nf_conntrack_get_ht(struct hlist_nulls_head **hash, unsigned int *hsize)
 321 {
 322         struct hlist_nulls_head *hptr;
 323         unsigned int sequence, hsz;
 324
 325         do {
 326                 sequence = read_seqcount_begin(&nf_conntrack_generation);
 327                 hsz = nf_conntrack_htable_size;
 328                 hptr = nf_conntrack_hash;
 329         } while (read_seqcount_retry(&nf_conntrack_generation, sequence));
 330
 331         *hash = hptr;
 332         *hsize = hsz;
 333 }
 334
 335 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
 336                                  const struct nf_conntrack_zone *zone,
 337                                  gfp_t flags);
 338 void nf_ct_tmpl_free(struct nf_conn *tmpl);
 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 */