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         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 #ifdef CONFIG_NETFILTER_DEBUG
  48 #define NF_CT_ASSERT(x)         WARN_ON(!(x))
  49 #else
  50 #define NF_CT_ASSERT(x)
  51 #endif
  52
  53 struct nf_conntrack_helper;
  54
  55 /* Must be kept in sync with the classes defined by helpers */
  56 #define NF_CT_MAX_EXPECT_CLASSES        4
  57
  58 /* nf_conn feature for connections that have a helper */
  59 struct nf_conn_help {
  60         /* Helper. if any */
  61         struct nf_conntrack_helper __rcu *helper;
  62
  63         struct hlist_head expectations;
  64
  65         /* Current number of expected connections */
  66         u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
  67
  68         /* private helper information. */
  69         char data[];
  70 };
  71
  72 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  73 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  74
  75 struct nf_conn {
  76         /* Usage count in here is 1 for hash table, 1 per skb,
  77          * plus 1 for any connection(s) we are `master' for
  78          *
  79          * Hint, SKB address this struct and refcnt via skb->nfct and
  80          * helpers nf_conntrack_get() and nf_conntrack_put().
  81          * Helper nf_ct_put() equals nf_conntrack_put() by dec refcnt,
  82          * beware nf_ct_get() is different and don't inc refcnt.
  83          */
  84         struct nf_conntrack ct_general;
  85
  86         spinlock_t      lock;
  87         u16             cpu;
  88
  89 #ifdef CONFIG_NF_CONNTRACK_ZONES
  90         struct nf_conntrack_zone zone;
  91 #endif
  92         /* XXX should I move this to the tail ? - Y.K */
  93         /* These are my tuples; original and reply */
  94         struct nf_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];
  95
  96         /* Have we seen traffic both ways yet? (bitset) */
  97         unsigned long status;
  98
  99         /* jiffies32 when this ct is considered dead */
 100         u32 timeout;
 101
 102         possible_net_t ct_net;
 103
 104 #if IS_ENABLED(CONFIG_NF_NAT)
 105         struct rhlist_head nat_bysource;
 106 #endif
 107         /* all members below initialized via memset */
 108         u8 __nfct_init_offset[0];
 109
 110         /* If we were expected by an expectation, this will be it */
 111         struct nf_conn *master;
 112
 113 #if defined(CONFIG_NF_CONNTRACK_MARK)
 114         u_int32_t mark;
 115 #endif
 116
 117 #ifdef CONFIG_NF_CONNTRACK_SECMARK
 118         u_int32_t secmark;
 119 #endif
 120
 121         /* Extensions */
 122         struct nf_ct_ext *ext;
 123
 124         /* Storage reserved for other modules, must be the last member */
 125         union nf_conntrack_proto proto;
 126 };
 127
 128 static inline struct nf_conn *
 129 nf_ct_tuplehash_to_ctrack(const struct nf_conntrack_tuple_hash *hash)
 130 {
 131         return container_of(hash, struct nf_conn,
 132                             tuplehash[hash->tuple.dst.dir]);
 133 }
 134
 135 static inline u_int16_t nf_ct_l3num(const struct nf_conn *ct)
 136 {
 137         return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
 138 }
 139
 140 static inline u_int8_t nf_ct_protonum(const struct nf_conn *ct)
 141 {
 142         return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum;
 143 }
 144
 145 #define nf_ct_tuple(ct, dir) (&(ct)->tuplehash[dir].tuple)
 146
 147 /* get master conntrack via master expectation */
 148 #define master_ct(conntr) (conntr->master)
 149
 150 extern struct net init_net;
 151
 152 static inline struct net *nf_ct_net(const struct nf_conn *ct)
 153 {
 154         return read_pnet(&ct->ct_net);
 155 }
 156
 157 /* Alter reply tuple (maybe alter helper). */
 158 void nf_conntrack_alter_reply(struct nf_conn *ct,
 159                               const struct nf_conntrack_tuple *newreply);
 160
 161 /* Is this tuple taken? (ignoring any belonging to the given
 162    conntrack). */
 163 int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 164                              const struct nf_conn *ignored_conntrack);
 165
 166 /* Return conntrack_info and tuple hash for given skb. */
 167 static inline struct nf_conn *
 168 nf_ct_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
 169 {
 170         *ctinfo = skb->nfctinfo;
 171         return (struct nf_conn *)skb->nfct;
 172 }
 173
 174 /* decrement reference count on a conntrack */
 175 static inline void nf_ct_put(struct nf_conn *ct)
 176 {
 177         NF_CT_ASSERT(ct);
 178         nf_conntrack_put(&ct->ct_general);
 179 }
 180
 181 /* Protocol module loading */
 182 int nf_ct_l3proto_try_module_get(unsigned short l3proto);
 183 void nf_ct_l3proto_module_put(unsigned short l3proto);
 184
 185 /* load module; enable/disable conntrack in this namespace */
 186 int nf_ct_netns_get(struct net *net, u8 nfproto);
 187 void nf_ct_netns_put(struct net *net, u8 nfproto);
 188
 189 /*
 190  * Allocate a hashtable of hlist_head (if nulls == 0),
 191  * or hlist_nulls_head (if nulls == 1)
 192  */
 193 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls);
 194
 195 void nf_ct_free_hashtable(void *hash, unsigned int size);
 196
 197 int nf_conntrack_hash_check_insert(struct nf_conn *ct);
 198 bool nf_ct_delete(struct nf_conn *ct, u32 pid, int report);
 199
 200 bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 201                        u_int16_t l3num, struct net *net,
 202                        struct nf_conntrack_tuple *tuple);
 203 bool nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
 204                           const struct nf_conntrack_tuple *orig);
 205
 206 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 207                           const struct sk_buff *skb,
 208                           unsigned long extra_jiffies, int do_acct);
 209
 210 /* Refresh conntrack for this many jiffies and do accounting */
 211 static inline void nf_ct_refresh_acct(struct nf_conn *ct,
 212                                       enum ip_conntrack_info ctinfo,
 213                                       const struct sk_buff *skb,
 214                                       unsigned long extra_jiffies)
 215 {
 216         __nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, 1);
 217 }
 218
 219 /* Refresh conntrack for this many jiffies */
 220 static inline void nf_ct_refresh(struct nf_conn *ct,
 221                                  const struct sk_buff *skb,
 222                                  unsigned long extra_jiffies)
 223 {
 224         __nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, 0);
 225 }
 226
 227 /* kill conntrack and do accounting */
 228 bool nf_ct_kill_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 229                      const struct sk_buff *skb);
 230
 231 /* kill conntrack without accounting */
 232 static inline bool nf_ct_kill(struct nf_conn *ct)
 233 {
 234         return nf_ct_delete(ct, 0, 0);
 235 }
 236
 237 /* These are for NAT.  Icky. */
 238 extern s32 (*nf_ct_nat_offset)(const struct nf_conn *ct,
 239                                enum ip_conntrack_dir dir,
 240                                u32 seq);
 241
 242 /* Fake conntrack entry for untracked connections */
 243 DECLARE_PER_CPU(struct nf_conn, nf_conntrack_untracked);
 244 static inline struct nf_conn *nf_ct_untracked_get(void)
 245 {
 246         return raw_cpu_ptr(&nf_conntrack_untracked);
 247 }
 248 void nf_ct_untracked_status_or(unsigned long bits);
 249
 250 /* Iterate over all conntracks: if iter returns true, it's deleted. */
 251 void nf_ct_iterate_cleanup(struct net *net,
 252                            int (*iter)(struct nf_conn *i, void *data),
 253                            void *data, u32 portid, int report);
 254
 255 struct nf_conntrack_zone;
 256
 257 void nf_conntrack_free(struct nf_conn *ct);
 258 struct nf_conn *nf_conntrack_alloc(struct net *net,
 259                                    const struct nf_conntrack_zone *zone,
 260                                    const struct nf_conntrack_tuple *orig,
 261                                    const struct nf_conntrack_tuple *repl,
 262                                    gfp_t gfp);
 263
 264 static inline int nf_ct_is_template(const struct nf_conn *ct)
 265 {
 266         return test_bit(IPS_TEMPLATE_BIT, &ct->status);
 267 }
 268
 269 /* It's confirmed if it is, or has been in the hash table. */
 270 static inline int nf_ct_is_confirmed(const struct nf_conn *ct)
 271 {
 272         return test_bit(IPS_CONFIRMED_BIT, &ct->status);
 273 }
 274
 275 static inline int nf_ct_is_dying(const struct nf_conn *ct)
 276 {
 277         return test_bit(IPS_DYING_BIT, &ct->status);
 278 }
 279
 280 static inline int nf_ct_is_untracked(const struct nf_conn *ct)
 281 {
 282         return test_bit(IPS_UNTRACKED_BIT, &ct->status);
 283 }
 284
 285 /* Packet is received from loopback */
 286 static inline bool nf_is_loopback_packet(const struct sk_buff *skb)
 287 {
 288         return skb->dev && skb->skb_iif && skb->dev->flags & IFF_LOOPBACK;
 289 }
 290
 291 #define nfct_time_stamp ((u32)(jiffies))
 292
 293 /* jiffies until ct expires, 0 if already expired */
 294 static inline unsigned long nf_ct_expires(const struct nf_conn *ct)
 295 {
 296         s32 timeout = ct->timeout - nfct_time_stamp;
 297
 298         return timeout > 0 ? timeout : 0;
 299 }
 300
 301 static inline bool nf_ct_is_expired(const struct nf_conn *ct)
 302 {
 303         return (__s32)(ct->timeout - nfct_time_stamp) <= 0;
 304 }
 305
 306 /* use after obtaining a reference count */
 307 static inline bool nf_ct_should_gc(const struct nf_conn *ct)
 308 {
 309         return nf_ct_is_expired(ct) && nf_ct_is_confirmed(ct) &&
 310                !nf_ct_is_dying(ct);
 311 }
 312
 313 struct kernel_param;
 314
 315 int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp);
 316 int nf_conntrack_hash_resize(unsigned int hashsize);
 317
 318 extern struct hlist_nulls_head *nf_conntrack_hash;
 319 extern unsigned int nf_conntrack_htable_size;
 320 extern seqcount_t nf_conntrack_generation;
 321 extern unsigned int nf_conntrack_max;
 322
 323 /* must be called with rcu read lock held */
 324 static inline void
 325 nf_conntrack_get_ht(struct hlist_nulls_head **hash, unsigned int *hsize)
 326 {
 327         struct hlist_nulls_head *hptr;
 328         unsigned int sequence, hsz;
 329
 330         do {
 331                 sequence = read_seqcount_begin(&nf_conntrack_generation);
 332                 hsz = nf_conntrack_htable_size;
 333                 hptr = nf_conntrack_hash;
 334         } while (read_seqcount_retry(&nf_conntrack_generation, sequence));
 335
 336         *hash = hptr;
 337         *hsize = hsz;
 338 }
 339
 340 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
 341                                  const struct nf_conntrack_zone *zone,
 342                                  gfp_t flags);
 343 void nf_ct_tmpl_free(struct nf_conn *tmpl);
 344
 345 static inline void
 346 nf_ct_set(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info info)
 347 {
 348         skb->nfct = &ct->ct_general;
 349         skb->nfctinfo = info;
 350 }
 351
 352 #define NF_CT_STAT_INC(net, count)        __this_cpu_inc((net)->ct.stat->count)
 353 #define NF_CT_STAT_INC_ATOMIC(net, count) this_cpu_inc((net)->ct.stat->count)
 354 #define NF_CT_STAT_ADD_ATOMIC(net, count, v) this_cpu_add((net)->ct.stat->count, (v))
 355
 356 #define MODULE_ALIAS_NFCT_HELPER(helper) \
 357         MODULE_ALIAS("nfct-helper-" helper)
 358
 359 #endif /* _NF_CONNTRACK_H */