include/net/udp.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Definitions for the UDP module.
   8  *
   9  * Version:     @(#)udp.h       1.0.2   05/07/93
  10  *
  11  * Authors:     Ross Biro
  12  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  13  *
  14  * Fixes:
  15  *              Alan Cox        : Turned on udp checksums. I don't want to
  16  *                                chase 'memory corruption' bugs that aren't!
  17  */
  18 #ifndef _UDP_H
  19 #define _UDP_H
  20
  21 #include <linux/list.h>
  22 #include <linux/bug.h>
  23 #include <net/inet_sock.h>
  24 #include <net/gso.h>
  25 #include <net/sock.h>
  26 #include <net/snmp.h>
  27 #include <net/ip.h>
  28 #include <linux/ipv6.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/poll.h>
  31 #include <linux/indirect_call_wrapper.h>
  32
  33 /**
  34  *      struct udp_skb_cb  -  UDP(-Lite) private variables
  35  *
  36  *      @header:      private variables used by IPv4/IPv6
  37  *      @cscov:       checksum coverage length (UDP-Lite only)
  38  *      @partial_cov: if set indicates partial csum coverage
  39  */
  40 struct udp_skb_cb {
  41         union {
  42                 struct inet_skb_parm    h4;
  43 #if IS_ENABLED(CONFIG_IPV6)
  44                 struct inet6_skb_parm   h6;
  45 #endif
  46         } header;
  47         __u16           cscov;
  48         __u8            partial_cov;
  49 };
  50 #define UDP_SKB_CB(__skb)       ((struct udp_skb_cb *)((__skb)->cb))
  51
  52 /**
  53  *      struct udp_hslot - UDP hash slot used by udp_table.hash/hash4
  54  *
  55  *      @head:  head of list of sockets
  56  *      @nulls_head:    head of list of sockets, only used by hash4
  57  *      @count: number of sockets in 'head' list
  58  *      @lock:  spinlock protecting changes to head/count
  59  */
  60 struct udp_hslot {
  61         union {
  62                 struct hlist_head       head;
  63                 /* hash4 uses hlist_nulls to avoid moving wrongly onto another
  64                  * hlist, because rehash() can happen with lookup().
  65                  */
  66                 struct hlist_nulls_head nulls_head;
  67         };
  68         int                     count;
  69         spinlock_t              lock;
  70 } __aligned(2 * sizeof(long));
  71
  72 /**
  73  *      struct udp_hslot_main - UDP hash slot used by udp_table.hash2
  74  *
  75  *      @hslot: basic hash slot
  76  *      @hash4_cnt: number of sockets in hslot4 of the same
  77  *                  (local port, local address)
  78  */
  79 struct udp_hslot_main {
  80         struct udp_hslot        hslot; /* must be the first member */
  81 #if !IS_ENABLED(CONFIG_BASE_SMALL)
  82         u32                     hash4_cnt;
  83 #endif
  84 } __aligned(2 * sizeof(long));
  85 #define UDP_HSLOT_MAIN(__hslot) ((struct udp_hslot_main *)(__hslot))
  86
  87 /**
  88  *      struct udp_table - UDP table
  89  *
  90  *      @hash:  hash table, sockets are hashed on (local port)
  91  *      @hash2: hash table, sockets are hashed on (local port, local address)
  92  *      @hash4: hash table, connected sockets are hashed on
  93  *              (local port, local address, remote port, remote address)
  94  *      @mask:  number of slots in hash tables, minus 1
  95  *      @log:   log2(number of slots in hash table)
  96  */
  97 struct udp_table {
  98         struct udp_hslot        *hash;
  99         struct udp_hslot_main   *hash2;
 100 #if !IS_ENABLED(CONFIG_BASE_SMALL)
 101         struct udp_hslot        *hash4;
 102 #endif
 103         unsigned int            mask;
 104         unsigned int            log;
 105 };
 106 extern struct udp_table udp_table;
 107 void udp_table_init(struct udp_table *, const char *);
 108 static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
 109                                              const struct net *net,
 110                                              unsigned int num)
 111 {
 112         return &table->hash[udp_hashfn(net, num, table->mask)];
 113 }
 114
 115 /*
 116  * For secondary hash, net_hash_mix() is performed before calling
 117  * udp_hashslot2(), this explains difference with udp_hashslot()
 118  */
 119 static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
 120                                               unsigned int hash)
 121 {
 122         return &table->hash2[hash & table->mask].hslot;
 123 }
 124
 125 #if IS_ENABLED(CONFIG_BASE_SMALL)
 126 static inline void udp_table_hash4_init(struct udp_table *table)
 127 {
 128 }
 129
 130 static inline struct udp_hslot *udp_hashslot4(struct udp_table *table,
 131                                               unsigned int hash)
 132 {
 133         BUILD_BUG();
 134         return NULL;
 135 }
 136
 137 static inline bool udp_hashed4(const struct sock *sk)
 138 {
 139         return false;
 140 }
 141
 142 static inline unsigned int udp_hash4_slot_size(void)
 143 {
 144         return 0;
 145 }
 146
 147 static inline bool udp_has_hash4(const struct udp_hslot *hslot2)
 148 {
 149         return false;
 150 }
 151
 152 static inline void udp_hash4_inc(struct udp_hslot *hslot2)
 153 {
 154 }
 155
 156 static inline void udp_hash4_dec(struct udp_hslot *hslot2)
 157 {
 158 }
 159 #else /* !CONFIG_BASE_SMALL */
 160
 161 /* Must be called with table->hash2 initialized */
 162 static inline void udp_table_hash4_init(struct udp_table *table)
 163 {
 164         table->hash4 = (void *)(table->hash2 + (table->mask + 1));
 165         for (int i = 0; i <= table->mask; i++) {
 166                 table->hash2[i].hash4_cnt = 0;
 167
 168                 INIT_HLIST_NULLS_HEAD(&table->hash4[i].nulls_head, i);
 169                 table->hash4[i].count = 0;
 170                 spin_lock_init(&table->hash4[i].lock);
 171         }
 172 }
 173
 174 static inline struct udp_hslot *udp_hashslot4(struct udp_table *table,
 175                                               unsigned int hash)
 176 {
 177         return &table->hash4[hash & table->mask];
 178 }
 179
 180 static inline bool udp_hashed4(const struct sock *sk)
 181 {
 182         return !hlist_nulls_unhashed(&udp_sk(sk)->udp_lrpa_node);
 183 }
 184
 185 static inline unsigned int udp_hash4_slot_size(void)
 186 {
 187         return sizeof(struct udp_hslot);
 188 }
 189
 190 static inline bool udp_has_hash4(const struct udp_hslot *hslot2)
 191 {
 192         return UDP_HSLOT_MAIN(hslot2)->hash4_cnt;
 193 }
 194
 195 static inline void udp_hash4_inc(struct udp_hslot *hslot2)
 196 {
 197         UDP_HSLOT_MAIN(hslot2)->hash4_cnt++;
 198 }
 199
 200 static inline void udp_hash4_dec(struct udp_hslot *hslot2)
 201 {
 202         UDP_HSLOT_MAIN(hslot2)->hash4_cnt--;
 203 }
 204 #endif /* CONFIG_BASE_SMALL */
 205
 206 extern struct proto udp_prot;
 207
 208 extern atomic_long_t udp_memory_allocated;
 209 DECLARE_PER_CPU(int, udp_memory_per_cpu_fw_alloc);
 210
 211 /* sysctl variables for udp */
 212 extern long sysctl_udp_mem[3];
 213 extern int sysctl_udp_rmem_min;
 214 extern int sysctl_udp_wmem_min;
 215
 216 struct sk_buff;
 217
 218 /*
 219  *      Generic checksumming routines for UDP(-Lite) v4 and v6
 220  */
 221 static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
 222 {
 223         return (UDP_SKB_CB(skb)->cscov == skb->len ?
 224                 __skb_checksum_complete(skb) :
 225                 __skb_checksum_complete_head(skb, UDP_SKB_CB(skb)->cscov));
 226 }
 227
 228 static inline int udp_lib_checksum_complete(struct sk_buff *skb)
 229 {
 230         return !skb_csum_unnecessary(skb) &&
 231                 __udp_lib_checksum_complete(skb);
 232 }
 233
 234 /**
 235  *      udp_csum_outgoing  -  compute UDPv4/v6 checksum over fragments
 236  *      @sk:    socket we are writing to
 237  *      @skb:   sk_buff containing the filled-in UDP header
 238  *              (checksum field must be zeroed out)
 239  */
 240 static inline __wsum udp_csum_outgoing(struct sock *sk, struct sk_buff *skb)
 241 {
 242         __wsum csum = csum_partial(skb_transport_header(skb),
 243                                    sizeof(struct udphdr), 0);
 244         skb_queue_walk(&sk->sk_write_queue, skb) {
 245                 csum = csum_add(csum, skb->csum);
 246         }
 247         return csum;
 248 }
 249
 250 static inline __wsum udp_csum(struct sk_buff *skb)
 251 {
 252         __wsum csum = csum_partial(skb_transport_header(skb),
 253                                    sizeof(struct udphdr), skb->csum);
 254
 255         for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next) {
 256                 csum = csum_add(csum, skb->csum);
 257         }
 258         return csum;
 259 }
 260
 261 static inline __sum16 udp_v4_check(int len, __be32 saddr,
 262                                    __be32 daddr, __wsum base)
 263 {
 264         return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base);
 265 }
 266
 267 void udp_set_csum(bool nocheck, struct sk_buff *skb,
 268                   __be32 saddr, __be32 daddr, int len);
 269
 270 static inline void udp_csum_pull_header(struct sk_buff *skb)
 271 {
 272         if (!skb->csum_valid && skb->ip_summed == CHECKSUM_NONE)
 273                 skb->csum = csum_partial(skb->data, sizeof(struct udphdr),
 274                                          skb->csum);
 275         skb_pull_rcsum(skb, sizeof(struct udphdr));
 276         UDP_SKB_CB(skb)->cscov -= sizeof(struct udphdr);
 277 }
 278
 279 typedef struct sock *(*udp_lookup_t)(const struct sk_buff *skb, __be16 sport,
 280                                      __be16 dport);
 281
 282 void udp_v6_early_demux(struct sk_buff *skb);
 283 INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));
 284
 285 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
 286                                   netdev_features_t features, bool is_ipv6);
 287
 288 static inline void udp_lib_init_sock(struct sock *sk)
 289 {
 290         struct udp_sock *up = udp_sk(sk);
 291
 292         skb_queue_head_init(&up->reader_queue);
 293         up->forward_threshold = sk->sk_rcvbuf >> 2;
 294         set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
 295 }
 296
 297 /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
 298 static inline int udp_lib_hash(struct sock *sk)
 299 {
 300         BUG();
 301         return 0;
 302 }
 303
 304 void udp_lib_unhash(struct sock *sk);
 305 void udp_lib_rehash(struct sock *sk, u16 new_hash, u16 new_hash4);
 306 u32 udp_ehashfn(const struct net *net, const __be32 laddr, const __u16 lport,
 307                 const __be32 faddr, const __be16 fport);
 308
 309 static inline void udp_lib_close(struct sock *sk, long timeout)
 310 {
 311         sk_common_release(sk);
 312 }
 313
 314 /* hash4 routines shared between UDPv4/6 */
 315 #if IS_ENABLED(CONFIG_BASE_SMALL)
 316 static inline void udp_lib_hash4(struct sock *sk, u16 hash)
 317 {
 318 }
 319
 320 static inline void udp4_hash4(struct sock *sk)
 321 {
 322 }
 323 #else /* !CONFIG_BASE_SMALL */
 324 void udp_lib_hash4(struct sock *sk, u16 hash);
 325 void udp4_hash4(struct sock *sk);
 326 #endif /* CONFIG_BASE_SMALL */
 327
 328 int udp_lib_get_port(struct sock *sk, unsigned short snum,
 329                      unsigned int hash2_nulladdr);
 330
 331 u32 udp_flow_hashrnd(void);
 332
 333 static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb,
 334                                        int min, int max, bool use_eth)
 335 {
 336         u32 hash;
 337
 338         if (min >= max) {
 339                 /* Use default range */
 340                 inet_get_local_port_range(net, &min, &max);
 341         }
 342
 343         hash = skb_get_hash(skb);
 344         if (unlikely(!hash)) {
 345                 if (use_eth) {
 346                         /* Can't find a normal hash, caller has indicated an
 347                          * Ethernet packet so use that to compute a hash.
 348                          */
 349                         hash = jhash(skb->data, 2 * ETH_ALEN,
 350                                      (__force u32) skb->protocol);
 351                 } else {
 352                         /* Can't derive any sort of hash for the packet, set
 353                          * to some consistent random value.
 354                          */
 355                         hash = udp_flow_hashrnd();
 356                 }
 357         }
 358
 359         /* Since this is being sent on the wire obfuscate hash a bit
 360          * to minimize possibility that any useful information to an
 361          * attacker is leaked. Only upper 16 bits are relevant in the
 362          * computation for 16 bit port value.
 363          */
 364         hash ^= hash << 16;
 365
 366         return htons((((u64) hash * (max - min)) >> 32) + min);
 367 }
 368
 369 static inline int udp_rqueue_get(struct sock *sk)
 370 {
 371         return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
 372 }
 373
 374 static inline bool udp_sk_bound_dev_eq(const struct net *net, int bound_dev_if,
 375                                        int dif, int sdif)
 376 {
 377 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 378         return inet_bound_dev_eq(!!READ_ONCE(net->ipv4.sysctl_udp_l3mdev_accept),
 379                                  bound_dev_if, dif, sdif);
 380 #else
 381         return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
 382 #endif
 383 }
 384
 385 /* net/ipv4/udp.c */
 386 void udp_destruct_common(struct sock *sk);
 387 void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
 388 int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb);
 389 void udp_skb_destructor(struct sock *sk, struct sk_buff *skb);
 390 struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags, int *off,
 391                                int *err);
 392 static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
 393                                            int *err)
 394 {
 395         int off = 0;
 396
 397         return __skb_recv_udp(sk, flags, &off, err);
 398 }
 399
 400 int udp_v4_early_demux(struct sk_buff *skb);
 401 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst);
 402 int udp_err(struct sk_buff *, u32);
 403 int udp_abort(struct sock *sk, int err);
 404 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
 405 void udp_splice_eof(struct socket *sock);
 406 int udp_push_pending_frames(struct sock *sk);
 407 void udp_flush_pending_frames(struct sock *sk);
 408 int udp_cmsg_send(struct sock *sk, struct msghdr *msg, u16 *gso_size);
 409 void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst);
 410 int udp_rcv(struct sk_buff *skb);
 411 int udp_ioctl(struct sock *sk, int cmd, int *karg);
 412 int udp_init_sock(struct sock *sk);
 413 int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 414 int __udp_disconnect(struct sock *sk, int flags);
 415 int udp_disconnect(struct sock *sk, int flags);
 416 __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait);
 417 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 418                                        netdev_features_t features,
 419                                        bool is_ipv6);
 420 int udp_lib_getsockopt(struct sock *sk, int level, int optname,
 421                        char __user *optval, int __user *optlen);
 422 int udp_lib_setsockopt(struct sock *sk, int level, int optname,
 423                        sockptr_t optval, unsigned int optlen,
 424                        int (*push_pending_frames)(struct sock *));
 425 struct sock *udp4_lib_lookup(const struct net *net, __be32 saddr, __be16 sport,
 426                              __be32 daddr, __be16 dport, int dif);
 427 struct sock *__udp4_lib_lookup(const struct net *net, __be32 saddr,
 428                                __be16 sport,
 429                                __be32 daddr, __be16 dport, int dif, int sdif,
 430                                struct udp_table *tbl, struct sk_buff *skb);
 431 struct sock *udp4_lib_lookup_skb(const struct sk_buff *skb,
 432                                  __be16 sport, __be16 dport);
 433 struct sock *udp6_lib_lookup(const struct net *net,
 434                              const struct in6_addr *saddr, __be16 sport,
 435                              const struct in6_addr *daddr, __be16 dport,
 436                              int dif);
 437 struct sock *__udp6_lib_lookup(const struct net *net,
 438                                const struct in6_addr *saddr, __be16 sport,
 439                                const struct in6_addr *daddr, __be16 dport,
 440                                int dif, int sdif, struct udp_table *tbl,
 441                                struct sk_buff *skb);
 442 struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
 443                                  __be16 sport, __be16 dport);
 444 int udp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
 445
 446 /* UDP uses skb->dev_scratch to cache as much information as possible and avoid
 447  * possibly multiple cache miss on dequeue()
 448  */
 449 struct udp_dev_scratch {
 450         /* skb->truesize and the stateless bit are embedded in a single field;
 451          * do not use a bitfield since the compiler emits better/smaller code
 452          * this way
 453          */
 454         u32 _tsize_state;
 455
 456 #if BITS_PER_LONG == 64
 457         /* len and the bit needed to compute skb_csum_unnecessary
 458          * will be on cold cache lines at recvmsg time.
 459          * skb->len can be stored on 16 bits since the udp header has been
 460          * already validated and pulled.
 461          */
 462         u16 len;
 463         bool is_linear;
 464         bool csum_unnecessary;
 465 #endif
 466 };
 467
 468 static inline struct udp_dev_scratch *udp_skb_scratch(struct sk_buff *skb)
 469 {
 470         return (struct udp_dev_scratch *)&skb->dev_scratch;
 471 }
 472
 473 #if BITS_PER_LONG == 64
 474 static inline unsigned int udp_skb_len(struct sk_buff *skb)
 475 {
 476         return udp_skb_scratch(skb)->len;
 477 }
 478
 479 static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
 480 {
 481         return udp_skb_scratch(skb)->csum_unnecessary;
 482 }
 483
 484 static inline bool udp_skb_is_linear(struct sk_buff *skb)
 485 {
 486         return udp_skb_scratch(skb)->is_linear;
 487 }
 488
 489 #else
 490 static inline unsigned int udp_skb_len(struct sk_buff *skb)
 491 {
 492         return skb->len;
 493 }
 494
 495 static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
 496 {
 497         return skb_csum_unnecessary(skb);
 498 }
 499
 500 static inline bool udp_skb_is_linear(struct sk_buff *skb)
 501 {
 502         return !skb_is_nonlinear(skb);
 503 }
 504 #endif
 505
 506 static inline int copy_linear_skb(struct sk_buff *skb, int len, int off,
 507                                   struct iov_iter *to)
 508 {
 509         return copy_to_iter_full(skb->data + off, len, to) ? 0 : -EFAULT;
 510 }
 511
 512 /*
 513  *      SNMP statistics for UDP and UDP-Lite
 514  */
 515 #define UDP_INC_STATS(net, field, is_udplite)                 do { \
 516         if (is_udplite) SNMP_INC_STATS((net)->mib.udplite_statistics, field);       \
 517         else            SNMP_INC_STATS((net)->mib.udp_statistics, field);  }  while(0)
 518 #define __UDP_INC_STATS(net, field, is_udplite)               do { \
 519         if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_statistics, field);         \
 520         else            __SNMP_INC_STATS((net)->mib.udp_statistics, field);    }  while(0)
 521
 522 #define __UDP6_INC_STATS(net, field, is_udplite)            do { \
 523         if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);\
 524         else            __SNMP_INC_STATS((net)->mib.udp_stats_in6, field);  \
 525 } while(0)
 526 #define UDP6_INC_STATS(net, field, __lite)                  do { \
 527         if (__lite) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);  \
 528         else        SNMP_INC_STATS((net)->mib.udp_stats_in6, field);      \
 529 } while(0)
 530
 531 #if IS_ENABLED(CONFIG_IPV6)
 532 #define __UDPX_MIB(sk, ipv4)                                            \
 533 ({                                                                      \
 534         ipv4 ? (IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics : \
 535                                  sock_net(sk)->mib.udp_statistics) :    \
 536                 (IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_stats_in6 : \
 537                                  sock_net(sk)->mib.udp_stats_in6);      \
 538 })
 539 #else
 540 #define __UDPX_MIB(sk, ipv4)                                            \
 541 ({                                                                      \
 542         IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics :         \
 543                          sock_net(sk)->mib.udp_statistics;              \
 544 })
 545 #endif
 546
 547 #define __UDPX_INC_STATS(sk, field) \
 548         __SNMP_INC_STATS(__UDPX_MIB(sk, (sk)->sk_family == AF_INET), field)
 549
 550 #ifdef CONFIG_PROC_FS
 551 struct udp_seq_afinfo {
 552         sa_family_t                     family;
 553         struct udp_table                *udp_table;
 554 };
 555
 556 struct udp_iter_state {
 557         struct seq_net_private  p;
 558         int                     bucket;
 559 };
 560
 561 void *udp_seq_start(struct seq_file *seq, loff_t *pos);
 562 void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
 563 void udp_seq_stop(struct seq_file *seq, void *v);
 564
 565 extern const struct seq_operations udp_seq_ops;
 566 extern const struct seq_operations udp6_seq_ops;
 567
 568 int udp4_proc_init(void);
 569 void udp4_proc_exit(void);
 570 #endif /* CONFIG_PROC_FS */
 571
 572 int udpv4_offload_init(void);
 573
 574 void udp_init(void);
 575
 576 DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
 577 void udp_encap_enable(void);
 578 void udp_encap_disable(void);
 579 #if IS_ENABLED(CONFIG_IPV6)
 580 DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
 581 void udpv6_encap_enable(void);
 582 #endif
 583
 584 static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
 585                                               struct sk_buff *skb, bool ipv4)
 586 {
 587         netdev_features_t features = NETIF_F_SG;
 588         struct sk_buff *segs;
 589
 590         /* Avoid csum recalculation by skb_segment unless userspace explicitly
 591          * asks for the final checksum values
 592          */
 593         if (!inet_get_convert_csum(sk))
 594                 features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
 595
 596         /* UDP segmentation expects packets of type CHECKSUM_PARTIAL or
 597          * CHECKSUM_NONE in __udp_gso_segment. UDP GRO indeed builds partial
 598          * packets in udp_gro_complete_segment. As does UDP GSO, verified by
 599          * udp_send_skb. But when those packets are looped in dev_loopback_xmit
 600          * their ip_summed CHECKSUM_NONE is changed to CHECKSUM_UNNECESSARY.
 601          * Reset in this specific case, where PARTIAL is both correct and
 602          * required.
 603          */
 604         if (skb->pkt_type == PACKET_LOOPBACK)
 605                 skb->ip_summed = CHECKSUM_PARTIAL;
 606
 607         /* the GSO CB lays after the UDP one, no need to save and restore any
 608          * CB fragment
 609          */
 610         segs = __skb_gso_segment(skb, features, false);
 611         if (IS_ERR_OR_NULL(segs)) {
 612                 int segs_nr = skb_shinfo(skb)->gso_segs;
 613
 614                 atomic_add(segs_nr, &sk->sk_drops);
 615                 SNMP_ADD_STATS(__UDPX_MIB(sk, ipv4), UDP_MIB_INERRORS, segs_nr);
 616                 kfree_skb(skb);
 617                 return NULL;
 618         }
 619
 620         consume_skb(skb);
 621         return segs;
 622 }
 623
 624 static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
 625 {
 626         /* UDP-lite can't land here - no GRO */
 627         WARN_ON_ONCE(UDP_SKB_CB(skb)->partial_cov);
 628
 629         /* UDP packets generated with UDP_SEGMENT and traversing:
 630          *
 631          * UDP tunnel(xmit) -> veth (segmentation) -> veth (gro) -> UDP tunnel (rx)
 632          *
 633          * can reach an UDP socket with CHECKSUM_NONE, because
 634          * __iptunnel_pull_header() converts CHECKSUM_PARTIAL into NONE.
 635          * SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST packets with no UDP tunnel will
 636          * have a valid checksum, as the GRO engine validates the UDP csum
 637          * before the aggregation and nobody strips such info in between.
 638          * Instead of adding another check in the tunnel fastpath, we can force
 639          * a valid csum after the segmentation.
 640          * Additionally fixup the UDP CB.
 641          */
 642         UDP_SKB_CB(skb)->cscov = skb->len;
 643         if (skb->ip_summed == CHECKSUM_NONE && !skb->csum_valid)
 644                 skb->csum_valid = 1;
 645 }
 646
 647 #ifdef CONFIG_BPF_SYSCALL
 648 struct sk_psock;
 649 int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
 650 #endif
 651
 652 #endif  /* _UDP_H */