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 #if IS_ENABLED(CONFIG_NF_NAT)
 104         struct rhlist_head nat_bysource;
 105 #endif
 106         /* all members below initialized via memset */
 107         u8 __nfct_init_offset[0];
 108
 109         /* If we were expected by an expectation, this will be it */
 110         struct nf_conn *master;
 111
 112 #if defined(CONFIG_NF_CONNTRACK_MARK)
 113         u_int32_t mark;
 114 #endif
 115
 116 #ifdef CONFIG_NF_CONNTRACK_SECMARK
 117         u_int32_t secmark;
 118 #endif
 119
 120         /* Extensions */
 121         struct nf_ct_ext *ext;
 122
 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 /* load module; enable/disable conntrack in this namespace */
 185 int nf_ct_netns_get(struct net *net, u8 nfproto);
 186 void nf_ct_netns_put(struct net *net, u8 nfproto);
 187
 188 /*
 189  * Allocate a hashtable of hlist_head (if nulls == 0),
 190  * or hlist_nulls_head (if nulls == 1)
 191  */
 192 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls);
 193
 194 void nf_ct_free_hashtable(void *hash, unsigned int size);
 195
 196 int nf_conntrack_hash_check_insert(struct nf_conn *ct);
 197 bool nf_ct_delete(struct nf_conn *ct, u32 pid, int report);
 198
 199 bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 200                        u_int16_t l3num, struct net *net,
 201                        struct nf_conntrack_tuple *tuple);
 202 bool nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
 203                           const struct nf_conntrack_tuple *orig);
 204
 205 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 206                           const struct sk_buff *skb,
 207                           unsigned long extra_jiffies, int do_acct);
 208
 209 /* Refresh conntrack for this many jiffies and do accounting */
 210 static inline void nf_ct_refresh_acct(struct nf_conn *ct,
 211                                       enum ip_conntrack_info ctinfo,
 212                                       const struct sk_buff *skb,
 213                                       unsigned long extra_jiffies)
 214 {
 215         __nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, 1);
 216 }
 217
 218 /* Refresh conntrack for this many jiffies */
 219 static inline void nf_ct_refresh(struct nf_conn *ct,
 220                                  const struct sk_buff *skb,
 221                                  unsigned long extra_jiffies)
 222 {
 223         __nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, 0);
 224 }
 225
 226 /* kill conntrack and do accounting */
 227 bool nf_ct_kill_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 228                      const struct sk_buff *skb);
 229
 230 /* kill conntrack without accounting */
 231 static inline bool nf_ct_kill(struct nf_conn *ct)
 232 {
 233         return nf_ct_delete(ct, 0, 0);
 234 }
 235
 236 /* These are for NAT.  Icky. */
 237 extern s32 (*nf_ct_nat_offset)(const struct nf_conn *ct,
 238                                enum ip_conntrack_dir dir,
 239                                u32 seq);
 240
 241 /* Fake conntrack entry for untracked connections */
 242 DECLARE_PER_CPU(struct nf_conn, nf_conntrack_untracked);
 243 static inline struct nf_conn *nf_ct_untracked_get(void)
 244 {
 245         return raw_cpu_ptr(&nf_conntrack_untracked);
 246 }
 247 void nf_ct_untracked_status_or(unsigned long bits);
 248
 249 /* Iterate over all conntracks: if iter returns true, it's deleted. */
 250 void nf_ct_iterate_cleanup(struct net *net,
 251                            int (*iter)(struct nf_conn *i, void *data),
 252                            void *data, u32 portid, int report);
 253
 254 struct nf_conntrack_zone;
 255
 256 void nf_conntrack_free(struct nf_conn *ct);
 257 struct nf_conn *nf_conntrack_alloc(struct net *net,
 258                                    const struct nf_conntrack_zone *zone,
 259                                    const struct nf_conntrack_tuple *orig,
 260                                    const struct nf_conntrack_tuple *repl,
 261                                    gfp_t gfp);
 262
 263 static inline int nf_ct_is_template(const struct nf_conn *ct)
 264 {
 265         return test_bit(IPS_TEMPLATE_BIT, &ct->status);
 266 }
 267
 268 /* It's confirmed if it is, or has been in the hash table. */
 269 static inline int nf_ct_is_confirmed(const struct nf_conn *ct)
 270 {
 271         return test_bit(IPS_CONFIRMED_BIT, &ct->status);
 272 }
 273
 274 static inline int nf_ct_is_dying(const struct nf_conn *ct)
 275 {
 276         return test_bit(IPS_DYING_BIT, &ct->status);
 277 }
 278
 279 static inline int nf_ct_is_untracked(const struct nf_conn *ct)
 280 {
 281         return test_bit(IPS_UNTRACKED_BIT, &ct->status);
 282 }
 283
 284 /* Packet is received from loopback */
 285 static inline bool nf_is_loopback_packet(const struct sk_buff *skb)
 286 {
 287         return skb->dev && skb->skb_iif && skb->dev->flags & IFF_LOOPBACK;
 288 }
 289
 290 #define nfct_time_stamp ((u32)(jiffies))
 291
 292 /* jiffies until ct expires, 0 if already expired */
 293 static inline unsigned long nf_ct_expires(const struct nf_conn *ct)
 294 {
 295         s32 timeout = ct->timeout - nfct_time_stamp;
 296
 297         return timeout > 0 ? timeout : 0;
 298 }
 299
 300 static inline bool nf_ct_is_expired(const struct nf_conn *ct)
 301 {
 302         return (__s32)(ct->timeout - nfct_time_stamp) <= 0;
 303 }
 304
 305 /* use after obtaining a reference count */
 306 static inline bool nf_ct_should_gc(const struct nf_conn *ct)
 307 {
 308         return nf_ct_is_expired(ct) && nf_ct_is_confirmed(ct) &&
 309                !nf_ct_is_dying(ct);
 310 }
 311
 312 struct kernel_param;
 313
 314 int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp);
 315 int nf_conntrack_hash_resize(unsigned int hashsize);
 316
 317 extern struct hlist_nulls_head *nf_conntrack_hash;
 318 extern unsigned int nf_conntrack_htable_size;
 319 extern seqcount_t nf_conntrack_generation;
 320 extern unsigned int nf_conntrack_max;
 321
 322 /* must be called with rcu read lock held */
 323 static inline void
 324 nf_conntrack_get_ht(struct hlist_nulls_head **hash, unsigned int *hsize)
 325 {
 326         struct hlist_nulls_head *hptr;
 327         unsigned int sequence, hsz;
 328
 329         do {
 330                 sequence = read_seqcount_begin(&nf_conntrack_generation);
 331                 hsz = nf_conntrack_htable_size;
 332                 hptr = nf_conntrack_hash;
 333         } while (read_seqcount_retry(&nf_conntrack_generation, sequence));
 334
 335         *hash = hptr;
 336         *hsize = hsz;
 337 }
 338
 339 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
 340                                  const struct nf_conntrack_zone *zone,
 341                                  gfp_t flags);
 342 void nf_ct_tmpl_free(struct nf_conn *tmpl);
 343
 344 #define NF_CT_STAT_INC(net, count)        __this_cpu_inc((net)->ct.stat->count)
 345 #define NF_CT_STAT_INC_ATOMIC(net, count) this_cpu_inc((net)->ct.stat->count)
 346 #define NF_CT_STAT_ADD_ATOMIC(net, count, v) this_cpu_add((net)->ct.stat->count, (v))
 347
 348 #define MODULE_ALIAS_NFCT_HELPER(helper) \
 349         MODULE_ALIAS("nfct-helper-" helper)
 350
 351 #endif /* _NF_CONNTRACK_H */