include/net/udp.h

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Definitions for the UDP module.
   7  *
   8  * Version:     @(#)udp.h       1.0.2   05/07/93
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *
  13  * Fixes:
  14  *              Alan Cox        : Turned on udp checksums. I don't want to
  15  *                                chase 'memory corruption' bugs that aren't!
  16  *
  17  *              This program is free software; you can redistribute it and/or
  18  *              modify it under the terms of the GNU General Public License
  19  *              as published by the Free Software Foundation; either version
  20  *              2 of the License, or (at your option) any later version.
  21  */
  22 #ifndef _UDP_H
  23 #define _UDP_H
  24
  25 #include <linux/list.h>
  26 #include <linux/bug.h>
  27 #include <net/inet_sock.h>
  28 #include <net/sock.h>
  29 #include <net/snmp.h>
  30 #include <net/ip.h>
  31 #include <linux/ipv6.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/poll.h>
  34
  35 /**
  36  *      struct udp_skb_cb  -  UDP(-Lite) private variables
  37  *
  38  *      @header:      private variables used by IPv4/IPv6
  39  *      @cscov:       checksum coverage length (UDP-Lite only)
  40  *      @partial_cov: if set indicates partial csum coverage
  41  */
  42 struct udp_skb_cb {
  43         union {
  44                 struct inet_skb_parm    h4;
  45 #if IS_ENABLED(CONFIG_IPV6)
  46                 struct inet6_skb_parm   h6;
  47 #endif
  48         } header;
  49         __u16           cscov;
  50         __u8            partial_cov;
  51 };
  52 #define UDP_SKB_CB(__skb)       ((struct udp_skb_cb *)((__skb)->cb))
  53
  54 /**
  55  *      struct udp_hslot - UDP hash slot
  56  *
  57  *      @head:  head of list of sockets
  58  *      @count: number of sockets in 'head' list
  59  *      @lock:  spinlock protecting changes to head/count
  60  */
  61 struct udp_hslot {
  62         struct hlist_head       head;
  63         int                     count;
  64         spinlock_t              lock;
  65 } __attribute__((aligned(2 * sizeof(long))));
  66
  67 /**
  68  *      struct udp_table - UDP table
  69  *
  70  *      @hash:  hash table, sockets are hashed on (local port)
  71  *      @hash2: hash table, sockets are hashed on (local port, local address)
  72  *      @mask:  number of slots in hash tables, minus 1
  73  *      @log:   log2(number of slots in hash table)
  74  */
  75 struct udp_table {
  76         struct udp_hslot        *hash;
  77         struct udp_hslot        *hash2;
  78         unsigned int            mask;
  79         unsigned int            log;
  80 };
  81 extern struct udp_table udp_table;
  82 void udp_table_init(struct udp_table *, const char *);
  83 static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
  84                                              struct net *net, unsigned int num)
  85 {
  86         return &table->hash[udp_hashfn(net, num, table->mask)];
  87 }
  88 /*
  89  * For secondary hash, net_hash_mix() is performed before calling
  90  * udp_hashslot2(), this explains difference with udp_hashslot()
  91  */
  92 static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
  93                                               unsigned int hash)
  94 {
  95         return &table->hash2[hash & table->mask];
  96 }
  97
  98 extern struct proto udp_prot;
  99
 100 extern atomic_long_t udp_memory_allocated;
 101
 102 /* sysctl variables for udp */
 103 extern long sysctl_udp_mem[3];
 104 extern int sysctl_udp_rmem_min;
 105 extern int sysctl_udp_wmem_min;
 106
 107 struct sk_buff;
 108
 109 /*
 110  *      Generic checksumming routines for UDP(-Lite) v4 and v6
 111  */
 112 static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
 113 {
 114         return (UDP_SKB_CB(skb)->cscov == skb->len ?
 115                 __skb_checksum_complete(skb) :
 116                 __skb_checksum_complete_head(skb, UDP_SKB_CB(skb)->cscov));
 117 }
 118
 119 static inline int udp_lib_checksum_complete(struct sk_buff *skb)
 120 {
 121         return !skb_csum_unnecessary(skb) &&
 122                 __udp_lib_checksum_complete(skb);
 123 }
 124
 125 /**
 126  *      udp_csum_outgoing  -  compute UDPv4/v6 checksum over fragments
 127  *      @sk:    socket we are writing to
 128  *      @skb:   sk_buff containing the filled-in UDP header
 129  *              (checksum field must be zeroed out)
 130  */
 131 static inline __wsum udp_csum_outgoing(struct sock *sk, struct sk_buff *skb)
 132 {
 133         __wsum csum = csum_partial(skb_transport_header(skb),
 134                                    sizeof(struct udphdr), 0);
 135         skb_queue_walk(&sk->sk_write_queue, skb) {
 136                 csum = csum_add(csum, skb->csum);
 137         }
 138         return csum;
 139 }
 140
 141 static inline __wsum udp_csum(struct sk_buff *skb)
 142 {
 143         __wsum csum = csum_partial(skb_transport_header(skb),
 144                                    sizeof(struct udphdr), skb->csum);
 145
 146         for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next) {
 147                 csum = csum_add(csum, skb->csum);
 148         }
 149         return csum;
 150 }
 151
 152 static inline __sum16 udp_v4_check(int len, __be32 saddr,
 153                                    __be32 daddr, __wsum base)
 154 {
 155         return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base);
 156 }
 157
 158 void udp_set_csum(bool nocheck, struct sk_buff *skb,
 159                   __be32 saddr, __be32 daddr, int len);
 160
 161 static inline void udp_csum_pull_header(struct sk_buff *skb)
 162 {
 163         if (!skb->csum_valid && skb->ip_summed == CHECKSUM_NONE)
 164                 skb->csum = csum_partial(skb->data, sizeof(struct udphdr),
 165                                          skb->csum);
 166         skb_pull_rcsum(skb, sizeof(struct udphdr));
 167         UDP_SKB_CB(skb)->cscov -= sizeof(struct udphdr);
 168 }
 169
 170 typedef struct sock *(*udp_lookup_t)(struct sk_buff *skb, __be16 sport,
 171                                      __be16 dport);
 172
 173 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 174                                  struct udphdr *uh, udp_lookup_t lookup);
 175 int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup);
 176
 177 static inline struct udphdr *udp_gro_udphdr(struct sk_buff *skb)
 178 {
 179         struct udphdr *uh;
 180         unsigned int hlen, off;
 181
 182         off  = skb_gro_offset(skb);
 183         hlen = off + sizeof(*uh);
 184         uh   = skb_gro_header_fast(skb, off);
 185         if (skb_gro_header_hard(skb, hlen))
 186                 uh = skb_gro_header_slow(skb, hlen, off);
 187
 188         return uh;
 189 }
 190
 191 /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
 192 static inline int udp_lib_hash(struct sock *sk)
 193 {
 194         BUG();
 195         return 0;
 196 }
 197
 198 void udp_lib_unhash(struct sock *sk);
 199 void udp_lib_rehash(struct sock *sk, u16 new_hash);
 200
 201 static inline void udp_lib_close(struct sock *sk, long timeout)
 202 {
 203         sk_common_release(sk);
 204 }
 205
 206 int udp_lib_get_port(struct sock *sk, unsigned short snum,
 207                      unsigned int hash2_nulladdr);
 208
 209 u32 udp_flow_hashrnd(void);
 210
 211 static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb,
 212                                        int min, int max, bool use_eth)
 213 {
 214         u32 hash;
 215
 216         if (min >= max) {
 217                 /* Use default range */
 218                 inet_get_local_port_range(net, &min, &max);
 219         }
 220
 221         hash = skb_get_hash(skb);
 222         if (unlikely(!hash)) {
 223                 if (use_eth) {
 224                         /* Can't find a normal hash, caller has indicated an
 225                          * Ethernet packet so use that to compute a hash.
 226                          */
 227                         hash = jhash(skb->data, 2 * ETH_ALEN,
 228                                      (__force u32) skb->protocol);
 229                 } else {
 230                         /* Can't derive any sort of hash for the packet, set
 231                          * to some consistent random value.
 232                          */
 233                         hash = udp_flow_hashrnd();
 234                 }
 235         }
 236
 237         /* Since this is being sent on the wire obfuscate hash a bit
 238          * to minimize possbility that any useful information to an
 239          * attacker is leaked. Only upper 16 bits are relevant in the
 240          * computation for 16 bit port value.
 241          */
 242         hash ^= hash << 16;
 243
 244         return htons((((u64) hash * (max - min)) >> 32) + min);
 245 }
 246
 247 static inline int udp_rqueue_get(struct sock *sk)
 248 {
 249         return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
 250 }
 251
 252 /* net/ipv4/udp.c */
 253 void udp_destruct_sock(struct sock *sk);
 254 void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
 255 int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb);
 256 void udp_skb_destructor(struct sock *sk, struct sk_buff *skb);
 257 struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
 258                                int noblock, int *peeked, int *off, int *err);
 259 static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
 260                                            int noblock, int *err)
 261 {
 262         int peeked, off = 0;
 263
 264         return __skb_recv_udp(sk, flags, noblock, &peeked, &off, err);
 265 }
 266
 267 int udp_v4_early_demux(struct sk_buff *skb);
 268 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst);
 269 int udp_get_port(struct sock *sk, unsigned short snum,
 270                  int (*saddr_cmp)(const struct sock *,
 271                                   const struct sock *));
 272 void udp_err(struct sk_buff *, u32);
 273 int udp_abort(struct sock *sk, int err);
 274 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
 275 int udp_push_pending_frames(struct sock *sk);
 276 void udp_flush_pending_frames(struct sock *sk);
 277 void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst);
 278 int udp_rcv(struct sk_buff *skb);
 279 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 280 int udp_init_sock(struct sock *sk);
 281 int __udp_disconnect(struct sock *sk, int flags);
 282 int udp_disconnect(struct sock *sk, int flags);
 283 unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait);
 284 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 285                                        netdev_features_t features,
 286                                        bool is_ipv6);
 287 int udp_lib_getsockopt(struct sock *sk, int level, int optname,
 288                        char __user *optval, int __user *optlen);
 289 int udp_lib_setsockopt(struct sock *sk, int level, int optname,
 290                        char __user *optval, unsigned int optlen,
 291                        int (*push_pending_frames)(struct sock *));
 292 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 293                              __be32 daddr, __be16 dport, int dif);
 294 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 295                                __be32 daddr, __be16 dport, int dif, int sdif,
 296                                struct udp_table *tbl, struct sk_buff *skb);
 297 struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
 298                                  __be16 sport, __be16 dport);
 299 struct sock *udp6_lib_lookup(struct net *net,
 300                              const struct in6_addr *saddr, __be16 sport,
 301                              const struct in6_addr *daddr, __be16 dport,
 302                              int dif);
 303 struct sock *__udp6_lib_lookup(struct net *net,
 304                                const struct in6_addr *saddr, __be16 sport,
 305                                const struct in6_addr *daddr, __be16 dport,
 306                                int dif, int sdif, struct udp_table *tbl,
 307                                struct sk_buff *skb);
 308 struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
 309                                  __be16 sport, __be16 dport);
 310
 311 /* UDP uses skb->dev_scratch to cache as much information as possible and avoid
 312  * possibly multiple cache miss on dequeue()
 313  */
 314 struct udp_dev_scratch {
 315         /* skb->truesize and the stateless bit are embedded in a single field;
 316          * do not use a bitfield since the compiler emits better/smaller code
 317          * this way
 318          */
 319         u32 _tsize_state;
 320
 321 #if BITS_PER_LONG == 64
 322         /* len and the bit needed to compute skb_csum_unnecessary
 323          * will be on cold cache lines at recvmsg time.
 324          * skb->len can be stored on 16 bits since the udp header has been
 325          * already validated and pulled.
 326          */
 327         u16 len;
 328         bool is_linear;
 329         bool csum_unnecessary;
 330 #endif
 331 };
 332
 333 static inline struct udp_dev_scratch *udp_skb_scratch(struct sk_buff *skb)
 334 {
 335         return (struct udp_dev_scratch *)&skb->dev_scratch;
 336 }
 337
 338 #if BITS_PER_LONG == 64
 339 static inline unsigned int udp_skb_len(struct sk_buff *skb)
 340 {
 341         return udp_skb_scratch(skb)->len;
 342 }
 343
 344 static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
 345 {
 346         return udp_skb_scratch(skb)->csum_unnecessary;
 347 }
 348
 349 static inline bool udp_skb_is_linear(struct sk_buff *skb)
 350 {
 351         return udp_skb_scratch(skb)->is_linear;
 352 }
 353
 354 #else
 355 static inline unsigned int udp_skb_len(struct sk_buff *skb)
 356 {
 357         return skb->len;
 358 }
 359
 360 static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
 361 {
 362         return skb_csum_unnecessary(skb);
 363 }
 364
 365 static inline bool udp_skb_is_linear(struct sk_buff *skb)
 366 {
 367         return !skb_is_nonlinear(skb);
 368 }
 369 #endif
 370
 371 static inline int copy_linear_skb(struct sk_buff *skb, int len, int off,
 372                                   struct iov_iter *to)
 373 {
 374         int n;
 375
 376         n = copy_to_iter(skb->data + off, len, to);
 377         if (n == len)
 378                 return 0;
 379
 380         iov_iter_revert(to, n);
 381         return -EFAULT;
 382 }
 383
 384 /*
 385  *      SNMP statistics for UDP and UDP-Lite
 386  */
 387 #define UDP_INC_STATS(net, field, is_udplite)                 do { \
 388         if (is_udplite) SNMP_INC_STATS((net)->mib.udplite_statistics, field);       \
 389         else            SNMP_INC_STATS((net)->mib.udp_statistics, field);  }  while(0)
 390 #define __UDP_INC_STATS(net, field, is_udplite)               do { \
 391         if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_statistics, field);         \
 392         else            __SNMP_INC_STATS((net)->mib.udp_statistics, field);    }  while(0)
 393
 394 #define __UDP6_INC_STATS(net, field, is_udplite)            do { \
 395         if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);\
 396         else            __SNMP_INC_STATS((net)->mib.udp_stats_in6, field);  \
 397 } while(0)
 398 #define UDP6_INC_STATS(net, field, __lite)                  do { \
 399         if (__lite) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);  \
 400         else        SNMP_INC_STATS((net)->mib.udp_stats_in6, field);      \
 401 } while(0)
 402
 403 #if IS_ENABLED(CONFIG_IPV6)
 404 #define __UDPX_INC_STATS(sk, field)                                     \
 405 do {                                                                    \
 406         if ((sk)->sk_family == AF_INET)                                 \
 407                 __UDP_INC_STATS(sock_net(sk), field, 0);                \
 408         else                                                            \
 409                 __UDP6_INC_STATS(sock_net(sk), field, 0);               \
 410 } while (0)
 411 #else
 412 #define __UDPX_INC_STATS(sk, field) __UDP_INC_STATS(sock_net(sk), field, 0)
 413 #endif
 414
 415 /* /proc */
 416 int udp_seq_open(struct inode *inode, struct file *file);
 417
 418 struct udp_seq_afinfo {
 419         char                            *name;
 420         sa_family_t                     family;
 421         struct udp_table                *udp_table;
 422         const struct file_operations    *seq_fops;
 423         struct seq_operations           seq_ops;
 424 };
 425
 426 struct udp_iter_state {
 427         struct seq_net_private  p;
 428         sa_family_t             family;
 429         int                     bucket;
 430         struct udp_table        *udp_table;
 431 };
 432
 433 #ifdef CONFIG_PROC_FS
 434 int udp_proc_register(struct net *net, struct udp_seq_afinfo *afinfo);
 435 void udp_proc_unregister(struct net *net, struct udp_seq_afinfo *afinfo);
 436
 437 int udp4_proc_init(void);
 438 void udp4_proc_exit(void);
 439 #endif
 440
 441 int udpv4_offload_init(void);
 442
 443 void udp_init(void);
 444
 445 void udp_encap_enable(void);
 446 #if IS_ENABLED(CONFIG_IPV6)
 447 void udpv6_encap_enable(void);
 448 #endif
 449
 450 #endif  /* _UDP_H */