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TOMOYO Linux Cross Reference
Linux/net/ipv4/udp.c

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  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  *              The User Datagram Protocol (UDP).
  7  *
  8  * Authors:     Ross Biro
  9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 10  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 11  *              Alan Cox, <alan@lxorguk.ukuu.org.uk>
 12  *              Hirokazu Takahashi, <taka@valinux.co.jp>
 13  *
 14  * Fixes:
 15  *              Alan Cox        :       verify_area() calls
 16  *              Alan Cox        :       stopped close while in use off icmp
 17  *                                      messages. Not a fix but a botch that
 18  *                                      for udp at least is 'valid'.
 19  *              Alan Cox        :       Fixed icmp handling properly
 20  *              Alan Cox        :       Correct error for oversized datagrams
 21  *              Alan Cox        :       Tidied select() semantics.
 22  *              Alan Cox        :       udp_err() fixed properly, also now
 23  *                                      select and read wake correctly on errors
 24  *              Alan Cox        :       udp_send verify_area moved to avoid mem leak
 25  *              Alan Cox        :       UDP can count its memory
 26  *              Alan Cox        :       send to an unknown connection causes
 27  *                                      an ECONNREFUSED off the icmp, but
 28  *                                      does NOT close.
 29  *              Alan Cox        :       Switched to new sk_buff handlers. No more backlog!
 30  *              Alan Cox        :       Using generic datagram code. Even smaller and the PEEK
 31  *                                      bug no longer crashes it.
 32  *              Fred Van Kempen :       Net2e support for sk->broadcast.
 33  *              Alan Cox        :       Uses skb_free_datagram
 34  *              Alan Cox        :       Added get/set sockopt support.
 35  *              Alan Cox        :       Broadcasting without option set returns EACCES.
 36  *              Alan Cox        :       No wakeup calls. Instead we now use the callbacks.
 37  *              Alan Cox        :       Use ip_tos and ip_ttl
 38  *              Alan Cox        :       SNMP Mibs
 39  *              Alan Cox        :       MSG_DONTROUTE, and 0.0.0.0 support.
 40  *              Matt Dillon     :       UDP length checks.
 41  *              Alan Cox        :       Smarter af_inet used properly.
 42  *              Alan Cox        :       Use new kernel side addressing.
 43  *              Alan Cox        :       Incorrect return on truncated datagram receive.
 44  *      Arnt Gulbrandsen        :       New udp_send and stuff
 45  *              Alan Cox        :       Cache last socket
 46  *              Alan Cox        :       Route cache
 47  *              Jon Peatfield   :       Minor efficiency fix to sendto().
 48  *              Mike Shaver     :       RFC1122 checks.
 49  *              Alan Cox        :       Nonblocking error fix.
 50  *      Willy Konynenberg       :       Transparent proxying support.
 51  *              Mike McLagan    :       Routing by source
 52  *              David S. Miller :       New socket lookup architecture.
 53  *                                      Last socket cache retained as it
 54  *                                      does have a high hit rate.
 55  *              Olaf Kirch      :       Don't linearise iovec on sendmsg.
 56  *              Andi Kleen      :       Some cleanups, cache destination entry
 57  *                                      for connect.
 58  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
 59  *              Melvin Smith    :       Check msg_name not msg_namelen in sendto(),
 60  *                                      return ENOTCONN for unconnected sockets (POSIX)
 61  *              Janos Farkas    :       don't deliver multi/broadcasts to a different
 62  *                                      bound-to-device socket
 63  *      Hirokazu Takahashi      :       HW checksumming for outgoing UDP
 64  *                                      datagrams.
 65  *      Hirokazu Takahashi      :       sendfile() on UDP works now.
 66  *              Arnaldo C. Melo :       convert /proc/net/udp to seq_file
 67  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
 68  *      Alexey Kuznetsov:               allow both IPv4 and IPv6 sockets to bind
 69  *                                      a single port at the same time.
 70  *      Derek Atkins <derek@ihtfp.com>: Add Encapulation Support
 71  *      James Chapman           :       Add L2TP encapsulation type.
 72  *
 73  *
 74  *              This program is free software; you can redistribute it and/or
 75  *              modify it under the terms of the GNU General Public License
 76  *              as published by the Free Software Foundation; either version
 77  *              2 of the License, or (at your option) any later version.
 78  */
 79 
 80 #define pr_fmt(fmt) "UDP: " fmt
 81 
 82 #include <linux/uaccess.h>
 83 #include <asm/ioctls.h>
 84 #include <linux/bootmem.h>
 85 #include <linux/highmem.h>
 86 #include <linux/swap.h>
 87 #include <linux/types.h>
 88 #include <linux/fcntl.h>
 89 #include <linux/module.h>
 90 #include <linux/socket.h>
 91 #include <linux/sockios.h>
 92 #include <linux/igmp.h>
 93 #include <linux/inetdevice.h>
 94 #include <linux/in.h>
 95 #include <linux/errno.h>
 96 #include <linux/timer.h>
 97 #include <linux/mm.h>
 98 #include <linux/inet.h>
 99 #include <linux/netdevice.h>
100 #include <linux/slab.h>
101 #include <net/tcp_states.h>
102 #include <linux/skbuff.h>
103 #include <linux/proc_fs.h>
104 #include <linux/seq_file.h>
105 #include <net/net_namespace.h>
106 #include <net/icmp.h>
107 #include <net/inet_hashtables.h>
108 #include <net/route.h>
109 #include <net/checksum.h>
110 #include <net/xfrm.h>
111 #include <trace/events/udp.h>
112 #include <linux/static_key.h>
113 #include <trace/events/skb.h>
114 #include <net/busy_poll.h>
115 #include "udp_impl.h"
116 #include <net/sock_reuseport.h>
117 #include <net/addrconf.h>
118 
119 struct udp_table udp_table __read_mostly;
120 EXPORT_SYMBOL(udp_table);
121 
122 long sysctl_udp_mem[3] __read_mostly;
123 EXPORT_SYMBOL(sysctl_udp_mem);
124 
125 int sysctl_udp_rmem_min __read_mostly;
126 EXPORT_SYMBOL(sysctl_udp_rmem_min);
127 
128 int sysctl_udp_wmem_min __read_mostly;
129 EXPORT_SYMBOL(sysctl_udp_wmem_min);
130 
131 atomic_long_t udp_memory_allocated;
132 EXPORT_SYMBOL(udp_memory_allocated);
133 
134 #define MAX_UDP_PORTS 65536
135 #define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN)
136 
137 /* IPCB reference means this can not be used from early demux */
138 static bool udp_lib_exact_dif_match(struct net *net, struct sk_buff *skb)
139 {
140 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
141         if (!net->ipv4.sysctl_udp_l3mdev_accept &&
142             skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
143                 return true;
144 #endif
145         return false;
146 }
147 
148 static int udp_lib_lport_inuse(struct net *net, __u16 num,
149                                const struct udp_hslot *hslot,
150                                unsigned long *bitmap,
151                                struct sock *sk, unsigned int log)
152 {
153         struct sock *sk2;
154         kuid_t uid = sock_i_uid(sk);
155 
156         sk_for_each(sk2, &hslot->head) {
157                 if (net_eq(sock_net(sk2), net) &&
158                     sk2 != sk &&
159                     (bitmap || udp_sk(sk2)->udp_port_hash == num) &&
160                     (!sk2->sk_reuse || !sk->sk_reuse) &&
161                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
162                      sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
163                     inet_rcv_saddr_equal(sk, sk2, true)) {
164                         if (sk2->sk_reuseport && sk->sk_reuseport &&
165                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
166                             uid_eq(uid, sock_i_uid(sk2))) {
167                                 if (!bitmap)
168                                         return 0;
169                         } else {
170                                 if (!bitmap)
171                                         return 1;
172                                 __set_bit(udp_sk(sk2)->udp_port_hash >> log,
173                                           bitmap);
174                         }
175                 }
176         }
177         return 0;
178 }
179 
180 /*
181  * Note: we still hold spinlock of primary hash chain, so no other writer
182  * can insert/delete a socket with local_port == num
183  */
184 static int udp_lib_lport_inuse2(struct net *net, __u16 num,
185                                 struct udp_hslot *hslot2,
186                                 struct sock *sk)
187 {
188         struct sock *sk2;
189         kuid_t uid = sock_i_uid(sk);
190         int res = 0;
191 
192         spin_lock(&hslot2->lock);
193         udp_portaddr_for_each_entry(sk2, &hslot2->head) {
194                 if (net_eq(sock_net(sk2), net) &&
195                     sk2 != sk &&
196                     (udp_sk(sk2)->udp_port_hash == num) &&
197                     (!sk2->sk_reuse || !sk->sk_reuse) &&
198                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
199                      sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
200                     inet_rcv_saddr_equal(sk, sk2, true)) {
201                         if (sk2->sk_reuseport && sk->sk_reuseport &&
202                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
203                             uid_eq(uid, sock_i_uid(sk2))) {
204                                 res = 0;
205                         } else {
206                                 res = 1;
207                         }
208                         break;
209                 }
210         }
211         spin_unlock(&hslot2->lock);
212         return res;
213 }
214 
215 static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot)
216 {
217         struct net *net = sock_net(sk);
218         kuid_t uid = sock_i_uid(sk);
219         struct sock *sk2;
220 
221         sk_for_each(sk2, &hslot->head) {
222                 if (net_eq(sock_net(sk2), net) &&
223                     sk2 != sk &&
224                     sk2->sk_family == sk->sk_family &&
225                     ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
226                     (udp_sk(sk2)->udp_port_hash == udp_sk(sk)->udp_port_hash) &&
227                     (sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
228                     sk2->sk_reuseport && uid_eq(uid, sock_i_uid(sk2)) &&
229                     inet_rcv_saddr_equal(sk, sk2, false)) {
230                         return reuseport_add_sock(sk, sk2);
231                 }
232         }
233 
234         return reuseport_alloc(sk);
235 }
236 
237 /**
238  *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
239  *
240  *  @sk:          socket struct in question
241  *  @snum:        port number to look up
242  *  @hash2_nulladdr: AF-dependent hash value in secondary hash chains,
243  *                   with NULL address
244  */
245 int udp_lib_get_port(struct sock *sk, unsigned short snum,
246                      unsigned int hash2_nulladdr)
247 {
248         struct udp_hslot *hslot, *hslot2;
249         struct udp_table *udptable = sk->sk_prot->h.udp_table;
250         int    error = 1;
251         struct net *net = sock_net(sk);
252 
253         if (!snum) {
254                 int low, high, remaining;
255                 unsigned int rand;
256                 unsigned short first, last;
257                 DECLARE_BITMAP(bitmap, PORTS_PER_CHAIN);
258 
259                 inet_get_local_port_range(net, &low, &high);
260                 remaining = (high - low) + 1;
261 
262                 rand = prandom_u32();
263                 first = reciprocal_scale(rand, remaining) + low;
264                 /*
265                  * force rand to be an odd multiple of UDP_HTABLE_SIZE
266                  */
267                 rand = (rand | 1) * (udptable->mask + 1);
268                 last = first + udptable->mask + 1;
269                 do {
270                         hslot = udp_hashslot(udptable, net, first);
271                         bitmap_zero(bitmap, PORTS_PER_CHAIN);
272                         spin_lock_bh(&hslot->lock);
273                         udp_lib_lport_inuse(net, snum, hslot, bitmap, sk,
274                                             udptable->log);
275 
276                         snum = first;
277                         /*
278                          * Iterate on all possible values of snum for this hash.
279                          * Using steps of an odd multiple of UDP_HTABLE_SIZE
280                          * give us randomization and full range coverage.
281                          */
282                         do {
283                                 if (low <= snum && snum <= high &&
284                                     !test_bit(snum >> udptable->log, bitmap) &&
285                                     !inet_is_local_reserved_port(net, snum))
286                                         goto found;
287                                 snum += rand;
288                         } while (snum != first);
289                         spin_unlock_bh(&hslot->lock);
290                         cond_resched();
291                 } while (++first != last);
292                 goto fail;
293         } else {
294                 hslot = udp_hashslot(udptable, net, snum);
295                 spin_lock_bh(&hslot->lock);
296                 if (hslot->count > 10) {
297                         int exist;
298                         unsigned int slot2 = udp_sk(sk)->udp_portaddr_hash ^ snum;
299 
300                         slot2          &= udptable->mask;
301                         hash2_nulladdr &= udptable->mask;
302 
303                         hslot2 = udp_hashslot2(udptable, slot2);
304                         if (hslot->count < hslot2->count)
305                                 goto scan_primary_hash;
306 
307                         exist = udp_lib_lport_inuse2(net, snum, hslot2, sk);
308                         if (!exist && (hash2_nulladdr != slot2)) {
309                                 hslot2 = udp_hashslot2(udptable, hash2_nulladdr);
310                                 exist = udp_lib_lport_inuse2(net, snum, hslot2,
311                                                              sk);
312                         }
313                         if (exist)
314                                 goto fail_unlock;
315                         else
316                                 goto found;
317                 }
318 scan_primary_hash:
319                 if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, 0))
320                         goto fail_unlock;
321         }
322 found:
323         inet_sk(sk)->inet_num = snum;
324         udp_sk(sk)->udp_port_hash = snum;
325         udp_sk(sk)->udp_portaddr_hash ^= snum;
326         if (sk_unhashed(sk)) {
327                 if (sk->sk_reuseport &&
328                     udp_reuseport_add_sock(sk, hslot)) {
329                         inet_sk(sk)->inet_num = 0;
330                         udp_sk(sk)->udp_port_hash = 0;
331                         udp_sk(sk)->udp_portaddr_hash ^= snum;
332                         goto fail_unlock;
333                 }
334 
335                 sk_add_node_rcu(sk, &hslot->head);
336                 hslot->count++;
337                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
338 
339                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
340                 spin_lock(&hslot2->lock);
341                 if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
342                     sk->sk_family == AF_INET6)
343                         hlist_add_tail_rcu(&udp_sk(sk)->udp_portaddr_node,
344                                            &hslot2->head);
345                 else
346                         hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
347                                            &hslot2->head);
348                 hslot2->count++;
349                 spin_unlock(&hslot2->lock);
350         }
351         sock_set_flag(sk, SOCK_RCU_FREE);
352         error = 0;
353 fail_unlock:
354         spin_unlock_bh(&hslot->lock);
355 fail:
356         return error;
357 }
358 EXPORT_SYMBOL(udp_lib_get_port);
359 
360 static u32 udp4_portaddr_hash(const struct net *net, __be32 saddr,
361                               unsigned int port)
362 {
363         return jhash_1word((__force u32)saddr, net_hash_mix(net)) ^ port;
364 }
365 
366 int udp_v4_get_port(struct sock *sk, unsigned short snum)
367 {
368         unsigned int hash2_nulladdr =
369                 udp4_portaddr_hash(sock_net(sk), htonl(INADDR_ANY), snum);
370         unsigned int hash2_partial =
371                 udp4_portaddr_hash(sock_net(sk), inet_sk(sk)->inet_rcv_saddr, 0);
372 
373         /* precompute partial secondary hash */
374         udp_sk(sk)->udp_portaddr_hash = hash2_partial;
375         return udp_lib_get_port(sk, snum, hash2_nulladdr);
376 }
377 
378 static int compute_score(struct sock *sk, struct net *net,
379                          __be32 saddr, __be16 sport,
380                          __be32 daddr, unsigned short hnum,
381                          int dif, int sdif, bool exact_dif)
382 {
383         int score;
384         struct inet_sock *inet;
385 
386         if (!net_eq(sock_net(sk), net) ||
387             udp_sk(sk)->udp_port_hash != hnum ||
388             ipv6_only_sock(sk))
389                 return -1;
390 
391         score = (sk->sk_family == PF_INET) ? 2 : 1;
392         inet = inet_sk(sk);
393 
394         if (inet->inet_rcv_saddr) {
395                 if (inet->inet_rcv_saddr != daddr)
396                         return -1;
397                 score += 4;
398         }
399 
400         if (inet->inet_daddr) {
401                 if (inet->inet_daddr != saddr)
402                         return -1;
403                 score += 4;
404         }
405 
406         if (inet->inet_dport) {
407                 if (inet->inet_dport != sport)
408                         return -1;
409                 score += 4;
410         }
411 
412         if (sk->sk_bound_dev_if || exact_dif) {
413                 bool dev_match = (sk->sk_bound_dev_if == dif ||
414                                   sk->sk_bound_dev_if == sdif);
415 
416                 if (exact_dif && !dev_match)
417                         return -1;
418                 if (sk->sk_bound_dev_if && dev_match)
419                         score += 4;
420         }
421 
422         if (sk->sk_incoming_cpu == raw_smp_processor_id())
423                 score++;
424         return score;
425 }
426 
427 static u32 udp_ehashfn(const struct net *net, const __be32 laddr,
428                        const __u16 lport, const __be32 faddr,
429                        const __be16 fport)
430 {
431         static u32 udp_ehash_secret __read_mostly;
432 
433         net_get_random_once(&udp_ehash_secret, sizeof(udp_ehash_secret));
434 
435         return __inet_ehashfn(laddr, lport, faddr, fport,
436                               udp_ehash_secret + net_hash_mix(net));
437 }
438 
439 /* called with rcu_read_lock() */
440 static struct sock *udp4_lib_lookup2(struct net *net,
441                                      __be32 saddr, __be16 sport,
442                                      __be32 daddr, unsigned int hnum,
443                                      int dif, int sdif, bool exact_dif,
444                                      struct udp_hslot *hslot2,
445                                      struct sk_buff *skb)
446 {
447         struct sock *sk, *result;
448         int score, badness, matches = 0, reuseport = 0;
449         u32 hash = 0;
450 
451         result = NULL;
452         badness = 0;
453         udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
454                 score = compute_score(sk, net, saddr, sport,
455                                       daddr, hnum, dif, sdif, exact_dif);
456                 if (score > badness) {
457                         reuseport = sk->sk_reuseport;
458                         if (reuseport) {
459                                 hash = udp_ehashfn(net, daddr, hnum,
460                                                    saddr, sport);
461                                 result = reuseport_select_sock(sk, hash, skb,
462                                                         sizeof(struct udphdr));
463                                 if (result)
464                                         return result;
465                                 matches = 1;
466                         }
467                         badness = score;
468                         result = sk;
469                 } else if (score == badness && reuseport) {
470                         matches++;
471                         if (reciprocal_scale(hash, matches) == 0)
472                                 result = sk;
473                         hash = next_pseudo_random32(hash);
474                 }
475         }
476         return result;
477 }
478 
479 /* UDP is nearly always wildcards out the wazoo, it makes no sense to try
480  * harder than this. -DaveM
481  */
482 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
483                 __be16 sport, __be32 daddr, __be16 dport, int dif,
484                 int sdif, struct udp_table *udptable, struct sk_buff *skb)
485 {
486         struct sock *sk, *result;
487         unsigned short hnum = ntohs(dport);
488         unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
489         struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
490         bool exact_dif = udp_lib_exact_dif_match(net, skb);
491         int score, badness, matches = 0, reuseport = 0;
492         u32 hash = 0;
493 
494         if (hslot->count > 10) {
495                 hash2 = udp4_portaddr_hash(net, daddr, hnum);
496                 slot2 = hash2 & udptable->mask;
497                 hslot2 = &udptable->hash2[slot2];
498                 if (hslot->count < hslot2->count)
499                         goto begin;
500 
501                 result = udp4_lib_lookup2(net, saddr, sport,
502                                           daddr, hnum, dif, sdif,
503                                           exact_dif, hslot2, skb);
504                 if (!result) {
505                         unsigned int old_slot2 = slot2;
506                         hash2 = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
507                         slot2 = hash2 & udptable->mask;
508                         /* avoid searching the same slot again. */
509                         if (unlikely(slot2 == old_slot2))
510                                 return result;
511 
512                         hslot2 = &udptable->hash2[slot2];
513                         if (hslot->count < hslot2->count)
514                                 goto begin;
515 
516                         result = udp4_lib_lookup2(net, saddr, sport,
517                                                   daddr, hnum, dif, sdif,
518                                                   exact_dif, hslot2, skb);
519                 }
520                 return result;
521         }
522 begin:
523         result = NULL;
524         badness = 0;
525         sk_for_each_rcu(sk, &hslot->head) {
526                 score = compute_score(sk, net, saddr, sport,
527                                       daddr, hnum, dif, sdif, exact_dif);
528                 if (score > badness) {
529                         reuseport = sk->sk_reuseport;
530                         if (reuseport) {
531                                 hash = udp_ehashfn(net, daddr, hnum,
532                                                    saddr, sport);
533                                 result = reuseport_select_sock(sk, hash, skb,
534                                                         sizeof(struct udphdr));
535                                 if (result)
536                                         return result;
537                                 matches = 1;
538                         }
539                         result = sk;
540                         badness = score;
541                 } else if (score == badness && reuseport) {
542                         matches++;
543                         if (reciprocal_scale(hash, matches) == 0)
544                                 result = sk;
545                         hash = next_pseudo_random32(hash);
546                 }
547         }
548         return result;
549 }
550 EXPORT_SYMBOL_GPL(__udp4_lib_lookup);
551 
552 static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
553                                                  __be16 sport, __be16 dport,
554                                                  struct udp_table *udptable)
555 {
556         const struct iphdr *iph = ip_hdr(skb);
557 
558         return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
559                                  iph->daddr, dport, inet_iif(skb),
560                                  inet_sdif(skb), udptable, skb);
561 }
562 
563 struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
564                                  __be16 sport, __be16 dport)
565 {
566         return __udp4_lib_lookup_skb(skb, sport, dport, &udp_table);
567 }
568 EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
569 
570 /* Must be called under rcu_read_lock().
571  * Does increment socket refcount.
572  */
573 #if IS_ENABLED(CONFIG_NETFILTER_XT_MATCH_SOCKET) || \
574     IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY) || \
575     IS_ENABLED(CONFIG_NF_SOCKET_IPV4)
576 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
577                              __be32 daddr, __be16 dport, int dif)
578 {
579         struct sock *sk;
580 
581         sk = __udp4_lib_lookup(net, saddr, sport, daddr, dport,
582                                dif, 0, &udp_table, NULL);
583         if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
584                 sk = NULL;
585         return sk;
586 }
587 EXPORT_SYMBOL_GPL(udp4_lib_lookup);
588 #endif
589 
590 static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk,
591                                        __be16 loc_port, __be32 loc_addr,
592                                        __be16 rmt_port, __be32 rmt_addr,
593                                        int dif, int sdif, unsigned short hnum)
594 {
595         struct inet_sock *inet = inet_sk(sk);
596 
597         if (!net_eq(sock_net(sk), net) ||
598             udp_sk(sk)->udp_port_hash != hnum ||
599             (inet->inet_daddr && inet->inet_daddr != rmt_addr) ||
600             (inet->inet_dport != rmt_port && inet->inet_dport) ||
601             (inet->inet_rcv_saddr && inet->inet_rcv_saddr != loc_addr) ||
602             ipv6_only_sock(sk) ||
603             (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif &&
604              sk->sk_bound_dev_if != sdif))
605                 return false;
606         if (!ip_mc_sf_allow(sk, loc_addr, rmt_addr, dif, sdif))
607                 return false;
608         return true;
609 }
610 
611 /*
612  * This routine is called by the ICMP module when it gets some
613  * sort of error condition.  If err < 0 then the socket should
614  * be closed and the error returned to the user.  If err > 0
615  * it's just the icmp type << 8 | icmp code.
616  * Header points to the ip header of the error packet. We move
617  * on past this. Then (as it used to claim before adjustment)
618  * header points to the first 8 bytes of the udp header.  We need
619  * to find the appropriate port.
620  */
621 
622 void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
623 {
624         struct inet_sock *inet;
625         const struct iphdr *iph = (const struct iphdr *)skb->data;
626         struct udphdr *uh = (struct udphdr *)(skb->data+(iph->ihl<<2));
627         const int type = icmp_hdr(skb)->type;
628         const int code = icmp_hdr(skb)->code;
629         struct sock *sk;
630         int harderr;
631         int err;
632         struct net *net = dev_net(skb->dev);
633 
634         sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
635                                iph->saddr, uh->source, skb->dev->ifindex, 0,
636                                udptable, NULL);
637         if (!sk) {
638                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
639                 return; /* No socket for error */
640         }
641 
642         err = 0;
643         harderr = 0;
644         inet = inet_sk(sk);
645 
646         switch (type) {
647         default:
648         case ICMP_TIME_EXCEEDED:
649                 err = EHOSTUNREACH;
650                 break;
651         case ICMP_SOURCE_QUENCH:
652                 goto out;
653         case ICMP_PARAMETERPROB:
654                 err = EPROTO;
655                 harderr = 1;
656                 break;
657         case ICMP_DEST_UNREACH:
658                 if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
659                         ipv4_sk_update_pmtu(skb, sk, info);
660                         if (inet->pmtudisc != IP_PMTUDISC_DONT) {
661                                 err = EMSGSIZE;
662                                 harderr = 1;
663                                 break;
664                         }
665                         goto out;
666                 }
667                 err = EHOSTUNREACH;
668                 if (code <= NR_ICMP_UNREACH) {
669                         harderr = icmp_err_convert[code].fatal;
670                         err = icmp_err_convert[code].errno;
671                 }
672                 break;
673         case ICMP_REDIRECT:
674                 ipv4_sk_redirect(skb, sk);
675                 goto out;
676         }
677 
678         /*
679          *      RFC1122: OK.  Passes ICMP errors back to application, as per
680          *      4.1.3.3.
681          */
682         if (!inet->recverr) {
683                 if (!harderr || sk->sk_state != TCP_ESTABLISHED)
684                         goto out;
685         } else
686                 ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1));
687 
688         sk->sk_err = err;
689         sk->sk_error_report(sk);
690 out:
691         return;
692 }
693 
694 void udp_err(struct sk_buff *skb, u32 info)
695 {
696         __udp4_lib_err(skb, info, &udp_table);
697 }
698 
699 /*
700  * Throw away all pending data and cancel the corking. Socket is locked.
701  */
702 void udp_flush_pending_frames(struct sock *sk)
703 {
704         struct udp_sock *up = udp_sk(sk);
705 
706         if (up->pending) {
707                 up->len = 0;
708                 up->pending = 0;
709                 ip_flush_pending_frames(sk);
710         }
711 }
712 EXPORT_SYMBOL(udp_flush_pending_frames);
713 
714 /**
715  *      udp4_hwcsum  -  handle outgoing HW checksumming
716  *      @skb:   sk_buff containing the filled-in UDP header
717  *              (checksum field must be zeroed out)
718  *      @src:   source IP address
719  *      @dst:   destination IP address
720  */
721 void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst)
722 {
723         struct udphdr *uh = udp_hdr(skb);
724         int offset = skb_transport_offset(skb);
725         int len = skb->len - offset;
726         int hlen = len;
727         __wsum csum = 0;
728 
729         if (!skb_has_frag_list(skb)) {
730                 /*
731                  * Only one fragment on the socket.
732                  */
733                 skb->csum_start = skb_transport_header(skb) - skb->head;
734                 skb->csum_offset = offsetof(struct udphdr, check);
735                 uh->check = ~csum_tcpudp_magic(src, dst, len,
736                                                IPPROTO_UDP, 0);
737         } else {
738                 struct sk_buff *frags;
739 
740                 /*
741                  * HW-checksum won't work as there are two or more
742                  * fragments on the socket so that all csums of sk_buffs
743                  * should be together
744                  */
745                 skb_walk_frags(skb, frags) {
746                         csum = csum_add(csum, frags->csum);
747                         hlen -= frags->len;
748                 }
749 
750                 csum = skb_checksum(skb, offset, hlen, csum);
751                 skb->ip_summed = CHECKSUM_NONE;
752 
753                 uh->check = csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum);
754                 if (uh->check == 0)
755                         uh->check = CSUM_MANGLED_0;
756         }
757 }
758 EXPORT_SYMBOL_GPL(udp4_hwcsum);
759 
760 /* Function to set UDP checksum for an IPv4 UDP packet. This is intended
761  * for the simple case like when setting the checksum for a UDP tunnel.
762  */
763 void udp_set_csum(bool nocheck, struct sk_buff *skb,
764                   __be32 saddr, __be32 daddr, int len)
765 {
766         struct udphdr *uh = udp_hdr(skb);
767 
768         if (nocheck) {
769                 uh->check = 0;
770         } else if (skb_is_gso(skb)) {
771                 uh->check = ~udp_v4_check(len, saddr, daddr, 0);
772         } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
773                 uh->check = 0;
774                 uh->check = udp_v4_check(len, saddr, daddr, lco_csum(skb));
775                 if (uh->check == 0)
776                         uh->check = CSUM_MANGLED_0;
777         } else {
778                 skb->ip_summed = CHECKSUM_PARTIAL;
779                 skb->csum_start = skb_transport_header(skb) - skb->head;
780                 skb->csum_offset = offsetof(struct udphdr, check);
781                 uh->check = ~udp_v4_check(len, saddr, daddr, 0);
782         }
783 }
784 EXPORT_SYMBOL(udp_set_csum);
785 
786 static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4)
787 {
788         struct sock *sk = skb->sk;
789         struct inet_sock *inet = inet_sk(sk);
790         struct udphdr *uh;
791         int err = 0;
792         int is_udplite = IS_UDPLITE(sk);
793         int offset = skb_transport_offset(skb);
794         int len = skb->len - offset;
795         __wsum csum = 0;
796 
797         /*
798          * Create a UDP header
799          */
800         uh = udp_hdr(skb);
801         uh->source = inet->inet_sport;
802         uh->dest = fl4->fl4_dport;
803         uh->len = htons(len);
804         uh->check = 0;
805 
806         if (is_udplite)                                  /*     UDP-Lite      */
807                 csum = udplite_csum(skb);
808 
809         else if (sk->sk_no_check_tx) {                   /* UDP csum off */
810 
811                 skb->ip_summed = CHECKSUM_NONE;
812                 goto send;
813 
814         } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
815 
816                 udp4_hwcsum(skb, fl4->saddr, fl4->daddr);
817                 goto send;
818 
819         } else
820                 csum = udp_csum(skb);
821 
822         /* add protocol-dependent pseudo-header */
823         uh->check = csum_tcpudp_magic(fl4->saddr, fl4->daddr, len,
824                                       sk->sk_protocol, csum);
825         if (uh->check == 0)
826                 uh->check = CSUM_MANGLED_0;
827 
828 send:
829         err = ip_send_skb(sock_net(sk), skb);
830         if (err) {
831                 if (err == -ENOBUFS && !inet->recverr) {
832                         UDP_INC_STATS(sock_net(sk),
833                                       UDP_MIB_SNDBUFERRORS, is_udplite);
834                         err = 0;
835                 }
836         } else
837                 UDP_INC_STATS(sock_net(sk),
838                               UDP_MIB_OUTDATAGRAMS, is_udplite);
839         return err;
840 }
841 
842 /*
843  * Push out all pending data as one UDP datagram. Socket is locked.
844  */
845 int udp_push_pending_frames(struct sock *sk)
846 {
847         struct udp_sock  *up = udp_sk(sk);
848         struct inet_sock *inet = inet_sk(sk);
849         struct flowi4 *fl4 = &inet->cork.fl.u.ip4;
850         struct sk_buff *skb;
851         int err = 0;
852 
853         skb = ip_finish_skb(sk, fl4);
854         if (!skb)
855                 goto out;
856 
857         err = udp_send_skb(skb, fl4);
858 
859 out:
860         up->len = 0;
861         up->pending = 0;
862         return err;
863 }
864 EXPORT_SYMBOL(udp_push_pending_frames);
865 
866 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
867 {
868         struct inet_sock *inet = inet_sk(sk);
869         struct udp_sock *up = udp_sk(sk);
870         struct flowi4 fl4_stack;
871         struct flowi4 *fl4;
872         int ulen = len;
873         struct ipcm_cookie ipc;
874         struct rtable *rt = NULL;
875         int free = 0;
876         int connected = 0;
877         __be32 daddr, faddr, saddr;
878         __be16 dport;
879         u8  tos;
880         int err, is_udplite = IS_UDPLITE(sk);
881         int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
882         int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
883         struct sk_buff *skb;
884         struct ip_options_data opt_copy;
885 
886         if (len > 0xFFFF)
887                 return -EMSGSIZE;
888 
889         /*
890          *      Check the flags.
891          */
892 
893         if (msg->msg_flags & MSG_OOB) /* Mirror BSD error message compatibility */
894                 return -EOPNOTSUPP;
895 
896         ipc.opt = NULL;
897         ipc.tx_flags = 0;
898         ipc.ttl = 0;
899         ipc.tos = -1;
900 
901         getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag;
902 
903         fl4 = &inet->cork.fl.u.ip4;
904         if (up->pending) {
905                 /*
906                  * There are pending frames.
907                  * The socket lock must be held while it's corked.
908                  */
909                 lock_sock(sk);
910                 if (likely(up->pending)) {
911                         if (unlikely(up->pending != AF_INET)) {
912                                 release_sock(sk);
913                                 return -EINVAL;
914                         }
915                         goto do_append_data;
916                 }
917                 release_sock(sk);
918         }
919         ulen += sizeof(struct udphdr);
920 
921         /*
922          *      Get and verify the address.
923          */
924         if (msg->msg_name) {
925                 DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
926                 if (msg->msg_namelen < sizeof(*usin))
927                         return -EINVAL;
928                 if (usin->sin_family != AF_INET) {
929                         if (usin->sin_family != AF_UNSPEC)
930                                 return -EAFNOSUPPORT;
931                 }
932 
933                 daddr = usin->sin_addr.s_addr;
934                 dport = usin->sin_port;
935                 if (dport == 0)
936                         return -EINVAL;
937         } else {
938                 if (sk->sk_state != TCP_ESTABLISHED)
939                         return -EDESTADDRREQ;
940                 daddr = inet->inet_daddr;
941                 dport = inet->inet_dport;
942                 /* Open fast path for connected socket.
943                    Route will not be used, if at least one option is set.
944                  */
945                 connected = 1;
946         }
947 
948         ipc.sockc.tsflags = sk->sk_tsflags;
949         ipc.addr = inet->inet_saddr;
950         ipc.oif = sk->sk_bound_dev_if;
951 
952         if (msg->msg_controllen) {
953                 err = ip_cmsg_send(sk, msg, &ipc, sk->sk_family == AF_INET6);
954                 if (unlikely(err)) {
955                         kfree(ipc.opt);
956                         return err;
957                 }
958                 if (ipc.opt)
959                         free = 1;
960                 connected = 0;
961         }
962         if (!ipc.opt) {
963                 struct ip_options_rcu *inet_opt;
964 
965                 rcu_read_lock();
966                 inet_opt = rcu_dereference(inet->inet_opt);
967                 if (inet_opt) {
968                         memcpy(&opt_copy, inet_opt,
969                                sizeof(*inet_opt) + inet_opt->opt.optlen);
970                         ipc.opt = &opt_copy.opt;
971                 }
972                 rcu_read_unlock();
973         }
974 
975         saddr = ipc.addr;
976         ipc.addr = faddr = daddr;
977 
978         sock_tx_timestamp(sk, ipc.sockc.tsflags, &ipc.tx_flags);
979 
980         if (ipc.opt && ipc.opt->opt.srr) {
981                 if (!daddr)
982                         return -EINVAL;
983                 faddr = ipc.opt->opt.faddr;
984                 connected = 0;
985         }
986         tos = get_rttos(&ipc, inet);
987         if (sock_flag(sk, SOCK_LOCALROUTE) ||
988             (msg->msg_flags & MSG_DONTROUTE) ||
989             (ipc.opt && ipc.opt->opt.is_strictroute)) {
990                 tos |= RTO_ONLINK;
991                 connected = 0;
992         }
993 
994         if (ipv4_is_multicast(daddr)) {
995                 if (!ipc.oif)
996                         ipc.oif = inet->mc_index;
997                 if (!saddr)
998                         saddr = inet->mc_addr;
999                 connected = 0;
1000         } else if (!ipc.oif)
1001                 ipc.oif = inet->uc_index;
1002 
1003         if (connected)
1004                 rt = (struct rtable *)sk_dst_check(sk, 0);
1005 
1006         if (!rt) {
1007                 struct net *net = sock_net(sk);
1008                 __u8 flow_flags = inet_sk_flowi_flags(sk);
1009 
1010                 fl4 = &fl4_stack;
1011 
1012                 flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
1013                                    RT_SCOPE_UNIVERSE, sk->sk_protocol,
1014                                    flow_flags,
1015                                    faddr, saddr, dport, inet->inet_sport,
1016                                    sk->sk_uid);
1017 
1018                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
1019                 rt = ip_route_output_flow(net, fl4, sk);
1020                 if (IS_ERR(rt)) {
1021                         err = PTR_ERR(rt);
1022                         rt = NULL;
1023                         if (err == -ENETUNREACH)
1024                                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
1025                         goto out;
1026                 }
1027 
1028                 err = -EACCES;
1029                 if ((rt->rt_flags & RTCF_BROADCAST) &&
1030                     !sock_flag(sk, SOCK_BROADCAST))
1031                         goto out;
1032                 if (connected)
1033                         sk_dst_set(sk, dst_clone(&rt->dst));
1034         }
1035 
1036         if (msg->msg_flags&MSG_CONFIRM)
1037                 goto do_confirm;
1038 back_from_confirm:
1039 
1040         saddr = fl4->saddr;
1041         if (!ipc.addr)
1042                 daddr = ipc.addr = fl4->daddr;
1043 
1044         /* Lockless fast path for the non-corking case. */
1045         if (!corkreq) {
1046                 skb = ip_make_skb(sk, fl4, getfrag, msg, ulen,
1047                                   sizeof(struct udphdr), &ipc, &rt,
1048                                   msg->msg_flags);
1049                 err = PTR_ERR(skb);
1050                 if (!IS_ERR_OR_NULL(skb))
1051                         err = udp_send_skb(skb, fl4);
1052                 goto out;
1053         }
1054 
1055         lock_sock(sk);
1056         if (unlikely(up->pending)) {
1057                 /* The socket is already corked while preparing it. */
1058                 /* ... which is an evident application bug. --ANK */
1059                 release_sock(sk);
1060 
1061                 net_dbg_ratelimited("socket already corked\n");
1062                 err = -EINVAL;
1063                 goto out;
1064         }
1065         /*
1066          *      Now cork the socket to pend data.
1067          */
1068         fl4 = &inet->cork.fl.u.ip4;
1069         fl4->daddr = daddr;
1070         fl4->saddr = saddr;
1071         fl4->fl4_dport = dport;
1072         fl4->fl4_sport = inet->inet_sport;
1073         up->pending = AF_INET;
1074 
1075 do_append_data:
1076         up->len += ulen;
1077         err = ip_append_data(sk, fl4, getfrag, msg, ulen,
1078                              sizeof(struct udphdr), &ipc, &rt,
1079                              corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
1080         if (err)
1081                 udp_flush_pending_frames(sk);
1082         else if (!corkreq)
1083                 err = udp_push_pending_frames(sk);
1084         else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
1085                 up->pending = 0;
1086         release_sock(sk);
1087 
1088 out:
1089         ip_rt_put(rt);
1090         if (free)
1091                 kfree(ipc.opt);
1092         if (!err)
1093                 return len;
1094         /*
1095          * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
1096          * ENOBUFS might not be good (it's not tunable per se), but otherwise
1097          * we don't have a good statistic (IpOutDiscards but it can be too many
1098          * things).  We could add another new stat but at least for now that
1099          * seems like overkill.
1100          */
1101         if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
1102                 UDP_INC_STATS(sock_net(sk),
1103                               UDP_MIB_SNDBUFERRORS, is_udplite);
1104         }
1105         return err;
1106 
1107 do_confirm:
1108         if (msg->msg_flags & MSG_PROBE)
1109                 dst_confirm_neigh(&rt->dst, &fl4->daddr);
1110         if (!(msg->msg_flags&MSG_PROBE) || len)
1111                 goto back_from_confirm;
1112         err = 0;
1113         goto out;
1114 }
1115 EXPORT_SYMBOL(udp_sendmsg);
1116 
1117 int udp_sendpage(struct sock *sk, struct page *page, int offset,
1118                  size_t size, int flags)
1119 {
1120         struct inet_sock *inet = inet_sk(sk);
1121         struct udp_sock *up = udp_sk(sk);
1122         int ret;
1123 
1124         if (flags & MSG_SENDPAGE_NOTLAST)
1125                 flags |= MSG_MORE;
1126 
1127         if (!up->pending) {
1128                 struct msghdr msg = {   .msg_flags = flags|MSG_MORE };
1129 
1130                 /* Call udp_sendmsg to specify destination address which
1131                  * sendpage interface can't pass.
1132                  * This will succeed only when the socket is connected.
1133                  */
1134                 ret = udp_sendmsg(sk, &msg, 0);
1135                 if (ret < 0)
1136                         return ret;
1137         }
1138 
1139         lock_sock(sk);
1140 
1141         if (unlikely(!up->pending)) {
1142                 release_sock(sk);
1143 
1144                 net_dbg_ratelimited("cork failed\n");
1145                 return -EINVAL;
1146         }
1147 
1148         ret = ip_append_page(sk, &inet->cork.fl.u.ip4,
1149                              page, offset, size, flags);
1150         if (ret == -EOPNOTSUPP) {
1151                 release_sock(sk);
1152                 return sock_no_sendpage(sk->sk_socket, page, offset,
1153                                         size, flags);
1154         }
1155         if (ret < 0) {
1156                 udp_flush_pending_frames(sk);
1157                 goto out;
1158         }
1159 
1160         up->len += size;
1161         if (!(up->corkflag || (flags&MSG_MORE)))
1162                 ret = udp_push_pending_frames(sk);
1163         if (!ret)
1164                 ret = size;
1165 out:
1166         release_sock(sk);
1167         return ret;
1168 }
1169 
1170 #define UDP_SKB_IS_STATELESS 0x80000000
1171 
1172 static void udp_set_dev_scratch(struct sk_buff *skb)
1173 {
1174         struct udp_dev_scratch *scratch = udp_skb_scratch(skb);
1175 
1176         BUILD_BUG_ON(sizeof(struct udp_dev_scratch) > sizeof(long));
1177         scratch->_tsize_state = skb->truesize;
1178 #if BITS_PER_LONG == 64
1179         scratch->len = skb->len;
1180         scratch->csum_unnecessary = !!skb_csum_unnecessary(skb);
1181         scratch->is_linear = !skb_is_nonlinear(skb);
1182 #endif
1183         /* all head states execept sp (dst, sk, nf) are always cleared by
1184          * udp_rcv() and we need to preserve secpath, if present, to eventually
1185          * process IP_CMSG_PASSSEC at recvmsg() time
1186          */
1187         if (likely(!skb_sec_path(skb)))
1188                 scratch->_tsize_state |= UDP_SKB_IS_STATELESS;
1189 }
1190 
1191 static int udp_skb_truesize(struct sk_buff *skb)
1192 {
1193         return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS;
1194 }
1195 
1196 static bool udp_skb_has_head_state(struct sk_buff *skb)
1197 {
1198         return !(udp_skb_scratch(skb)->_tsize_state & UDP_SKB_IS_STATELESS);
1199 }
1200 
1201 /* fully reclaim rmem/fwd memory allocated for skb */
1202 static void udp_rmem_release(struct sock *sk, int size, int partial,
1203                              bool rx_queue_lock_held)
1204 {
1205         struct udp_sock *up = udp_sk(sk);
1206         struct sk_buff_head *sk_queue;
1207         int amt;
1208 
1209         if (likely(partial)) {
1210                 up->forward_deficit += size;
1211                 size = up->forward_deficit;
1212                 if (size < (sk->sk_rcvbuf >> 2))
1213                         return;
1214         } else {
1215                 size += up->forward_deficit;
1216         }
1217         up->forward_deficit = 0;
1218 
1219         /* acquire the sk_receive_queue for fwd allocated memory scheduling,
1220          * if the called don't held it already
1221          */
1222         sk_queue = &sk->sk_receive_queue;
1223         if (!rx_queue_lock_held)
1224                 spin_lock(&sk_queue->lock);
1225 
1226 
1227         sk->sk_forward_alloc += size;
1228         amt = (sk->sk_forward_alloc - partial) & ~(SK_MEM_QUANTUM - 1);
1229         sk->sk_forward_alloc -= amt;
1230 
1231         if (amt)
1232                 __sk_mem_reduce_allocated(sk, amt >> SK_MEM_QUANTUM_SHIFT);
1233 
1234         atomic_sub(size, &sk->sk_rmem_alloc);
1235 
1236         /* this can save us from acquiring the rx queue lock on next receive */
1237         skb_queue_splice_tail_init(sk_queue, &up->reader_queue);
1238 
1239         if (!rx_queue_lock_held)
1240                 spin_unlock(&sk_queue->lock);
1241 }
1242 
1243 /* Note: called with reader_queue.lock held.
1244  * Instead of using skb->truesize here, find a copy of it in skb->dev_scratch
1245  * This avoids a cache line miss while receive_queue lock is held.
1246  * Look at __udp_enqueue_schedule_skb() to find where this copy is done.
1247  */
1248 void udp_skb_destructor(struct sock *sk, struct sk_buff *skb)
1249 {
1250         prefetch(&skb->data);
1251         udp_rmem_release(sk, udp_skb_truesize(skb), 1, false);
1252 }
1253 EXPORT_SYMBOL(udp_skb_destructor);
1254 
1255 /* as above, but the caller held the rx queue lock, too */
1256 static void udp_skb_dtor_locked(struct sock *sk, struct sk_buff *skb)
1257 {
1258         prefetch(&skb->data);
1259         udp_rmem_release(sk, udp_skb_truesize(skb), 1, true);
1260 }
1261 
1262 /* Idea of busylocks is to let producers grab an extra spinlock
1263  * to relieve pressure on the receive_queue spinlock shared by consumer.
1264  * Under flood, this means that only one producer can be in line
1265  * trying to acquire the receive_queue spinlock.
1266  * These busylock can be allocated on a per cpu manner, instead of a
1267  * per socket one (that would consume a cache line per socket)
1268  */
1269 static int udp_busylocks_log __read_mostly;
1270 static spinlock_t *udp_busylocks __read_mostly;
1271 
1272 static spinlock_t *busylock_acquire(void *ptr)
1273 {
1274         spinlock_t *busy;
1275 
1276         busy = udp_busylocks + hash_ptr(ptr, udp_busylocks_log);
1277         spin_lock(busy);
1278         return busy;
1279 }
1280 
1281 static void busylock_release(spinlock_t *busy)
1282 {
1283         if (busy)
1284                 spin_unlock(busy);
1285 }
1286 
1287 int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
1288 {
1289         struct sk_buff_head *list = &sk->sk_receive_queue;
1290         int rmem, delta, amt, err = -ENOMEM;
1291         spinlock_t *busy = NULL;
1292         int size;
1293 
1294         /* try to avoid the costly atomic add/sub pair when the receive
1295          * queue is full; always allow at least a packet
1296          */
1297         rmem = atomic_read(&sk->sk_rmem_alloc);
1298         if (rmem > sk->sk_rcvbuf)
1299                 goto drop;
1300 
1301         /* Under mem pressure, it might be helpful to help udp_recvmsg()
1302          * having linear skbs :
1303          * - Reduce memory overhead and thus increase receive queue capacity
1304          * - Less cache line misses at copyout() time
1305          * - Less work at consume_skb() (less alien page frag freeing)
1306          */
1307         if (rmem > (sk->sk_rcvbuf >> 1)) {
1308                 skb_condense(skb);
1309 
1310                 busy = busylock_acquire(sk);
1311         }
1312         size = skb->truesize;
1313         udp_set_dev_scratch(skb);
1314 
1315         /* we drop only if the receive buf is full and the receive
1316          * queue contains some other skb
1317          */
1318         rmem = atomic_add_return(size, &sk->sk_rmem_alloc);
1319         if (rmem > (size + sk->sk_rcvbuf))
1320                 goto uncharge_drop;
1321 
1322         spin_lock(&list->lock);
1323         if (size >= sk->sk_forward_alloc) {
1324                 amt = sk_mem_pages(size);
1325                 delta = amt << SK_MEM_QUANTUM_SHIFT;
1326                 if (!__sk_mem_raise_allocated(sk, delta, amt, SK_MEM_RECV)) {
1327                         err = -ENOBUFS;
1328                         spin_unlock(&list->lock);
1329                         goto uncharge_drop;
1330                 }
1331 
1332                 sk->sk_forward_alloc += delta;
1333         }
1334 
1335         sk->sk_forward_alloc -= size;
1336 
1337         /* no need to setup a destructor, we will explicitly release the
1338          * forward allocated memory on dequeue
1339          */
1340         sock_skb_set_dropcount(sk, skb);
1341 
1342         __skb_queue_tail(list, skb);
1343         spin_unlock(&list->lock);
1344 
1345         if (!sock_flag(sk, SOCK_DEAD))
1346                 sk->sk_data_ready(sk);
1347 
1348         busylock_release(busy);
1349         return 0;
1350 
1351 uncharge_drop:
1352         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
1353 
1354 drop:
1355         atomic_inc(&sk->sk_drops);
1356         busylock_release(busy);
1357         return err;
1358 }
1359 EXPORT_SYMBOL_GPL(__udp_enqueue_schedule_skb);
1360 
1361 void udp_destruct_sock(struct sock *sk)
1362 {
1363         /* reclaim completely the forward allocated memory */
1364         struct udp_sock *up = udp_sk(sk);
1365         unsigned int total = 0;
1366         struct sk_buff *skb;
1367 
1368         skb_queue_splice_tail_init(&sk->sk_receive_queue, &up->reader_queue);
1369         while ((skb = __skb_dequeue(&up->reader_queue)) != NULL) {
1370                 total += skb->truesize;
1371                 kfree_skb(skb);
1372         }
1373         udp_rmem_release(sk, total, 0, true);
1374 
1375         inet_sock_destruct(sk);
1376 }
1377 EXPORT_SYMBOL_GPL(udp_destruct_sock);
1378 
1379 int udp_init_sock(struct sock *sk)
1380 {
1381         skb_queue_head_init(&udp_sk(sk)->reader_queue);
1382         sk->sk_destruct = udp_destruct_sock;
1383         return 0;
1384 }
1385 EXPORT_SYMBOL_GPL(udp_init_sock);
1386 
1387 void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
1388 {
1389         if (unlikely(READ_ONCE(sk->sk_peek_off) >= 0)) {
1390                 bool slow = lock_sock_fast(sk);
1391 
1392                 sk_peek_offset_bwd(sk, len);
1393                 unlock_sock_fast(sk, slow);
1394         }
1395 
1396         if (!skb_unref(skb))
1397                 return;
1398 
1399         /* In the more common cases we cleared the head states previously,
1400          * see __udp_queue_rcv_skb().
1401          */
1402         if (unlikely(udp_skb_has_head_state(skb)))
1403                 skb_release_head_state(skb);
1404         __consume_stateless_skb(skb);
1405 }
1406 EXPORT_SYMBOL_GPL(skb_consume_udp);
1407 
1408 static struct sk_buff *__first_packet_length(struct sock *sk,
1409                                              struct sk_buff_head *rcvq,
1410                                              int *total)
1411 {
1412         struct sk_buff *skb;
1413 
1414         while ((skb = skb_peek(rcvq)) != NULL) {
1415                 if (udp_lib_checksum_complete(skb)) {
1416                         __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS,
1417                                         IS_UDPLITE(sk));
1418                         __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS,
1419                                         IS_UDPLITE(sk));
1420                         atomic_inc(&sk->sk_drops);
1421                         __skb_unlink(skb, rcvq);
1422                         *total += skb->truesize;
1423                         kfree_skb(skb);
1424                 } else {
1425                         /* the csum related bits could be changed, refresh
1426                          * the scratch area
1427                          */
1428                         udp_set_dev_scratch(skb);
1429                         break;
1430                 }
1431         }
1432         return skb;
1433 }
1434 
1435 /**
1436  *      first_packet_length     - return length of first packet in receive queue
1437  *      @sk: socket
1438  *
1439  *      Drops all bad checksum frames, until a valid one is found.
1440  *      Returns the length of found skb, or -1 if none is found.
1441  */
1442 static int first_packet_length(struct sock *sk)
1443 {
1444         struct sk_buff_head *rcvq = &udp_sk(sk)->reader_queue;
1445         struct sk_buff_head *sk_queue = &sk->sk_receive_queue;
1446         struct sk_buff *skb;
1447         int total = 0;
1448         int res;
1449 
1450         spin_lock_bh(&rcvq->lock);
1451         skb = __first_packet_length(sk, rcvq, &total);
1452         if (!skb && !skb_queue_empty(sk_queue)) {
1453                 spin_lock(&sk_queue->lock);
1454                 skb_queue_splice_tail_init(sk_queue, rcvq);
1455                 spin_unlock(&sk_queue->lock);
1456 
1457                 skb = __first_packet_length(sk, rcvq, &total);
1458         }
1459         res = skb ? skb->len : -1;
1460         if (total)
1461                 udp_rmem_release(sk, total, 1, false);
1462         spin_unlock_bh(&rcvq->lock);
1463         return res;
1464 }
1465 
1466 /*
1467  *      IOCTL requests applicable to the UDP protocol
1468  */
1469 
1470 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
1471 {
1472         switch (cmd) {
1473         case SIOCOUTQ:
1474         {
1475                 int amount = sk_wmem_alloc_get(sk);
1476 
1477                 return put_user(amount, (int __user *)arg);
1478         }
1479 
1480         case SIOCINQ:
1481         {
1482                 int amount = max_t(int, 0, first_packet_length(sk));
1483 
1484                 return put_user(amount, (int __user *)arg);
1485         }
1486 
1487         default:
1488                 return -ENOIOCTLCMD;
1489         }
1490 
1491         return 0;
1492 }
1493 EXPORT_SYMBOL(udp_ioctl);
1494 
1495 struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
1496                                int noblock, int *peeked, int *off, int *err)
1497 {
1498         struct sk_buff_head *sk_queue = &sk->sk_receive_queue;
1499         struct sk_buff_head *queue;
1500         struct sk_buff *last;
1501         long timeo;
1502         int error;
1503 
1504         queue = &udp_sk(sk)->reader_queue;
1505         flags |= noblock ? MSG_DONTWAIT : 0;
1506         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1507         do {
1508                 struct sk_buff *skb;
1509 
1510                 error = sock_error(sk);
1511                 if (error)
1512                         break;
1513 
1514                 error = -EAGAIN;
1515                 *peeked = 0;
1516                 do {
1517                         spin_lock_bh(&queue->lock);
1518                         skb = __skb_try_recv_from_queue(sk, queue, flags,
1519                                                         udp_skb_destructor,
1520                                                         peeked, off, err,
1521                                                         &last);
1522                         if (skb) {
1523                                 spin_unlock_bh(&queue->lock);
1524                                 return skb;
1525                         }
1526 
1527                         if (skb_queue_empty(sk_queue)) {
1528                                 spin_unlock_bh(&queue->lock);
1529                                 goto busy_check;
1530                         }
1531 
1532                         /* refill the reader queue and walk it again
1533                          * keep both queues locked to avoid re-acquiring
1534                          * the sk_receive_queue lock if fwd memory scheduling
1535                          * is needed.
1536                          */
1537                         spin_lock(&sk_queue->lock);
1538                         skb_queue_splice_tail_init(sk_queue, queue);
1539 
1540                         skb = __skb_try_recv_from_queue(sk, queue, flags,
1541                                                         udp_skb_dtor_locked,
1542                                                         peeked, off, err,
1543                                                         &last);
1544                         spin_unlock(&sk_queue->lock);
1545                         spin_unlock_bh(&queue->lock);
1546                         if (skb)
1547                                 return skb;
1548 
1549 busy_check:
1550                         if (!sk_can_busy_loop(sk))
1551                                 break;
1552 
1553                         sk_busy_loop(sk, flags & MSG_DONTWAIT);
1554                 } while (!skb_queue_empty(sk_queue));
1555 
1556                 /* sk_queue is empty, reader_queue may contain peeked packets */
1557         } while (timeo &&
1558                  !__skb_wait_for_more_packets(sk, &error, &timeo,
1559                                               (struct sk_buff *)sk_queue));
1560 
1561         *err = error;
1562         return NULL;
1563 }
1564 EXPORT_SYMBOL_GPL(__skb_recv_udp);
1565 
1566 /*
1567  *      This should be easy, if there is something there we
1568  *      return it, otherwise we block.
1569  */
1570 
1571 int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
1572                 int flags, int *addr_len)
1573 {
1574         struct inet_sock *inet = inet_sk(sk);
1575         DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
1576         struct sk_buff *skb;
1577         unsigned int ulen, copied;
1578         int peeked, peeking, off;
1579         int err;
1580         int is_udplite = IS_UDPLITE(sk);
1581         bool checksum_valid = false;
1582 
1583         if (flags & MSG_ERRQUEUE)
1584                 return ip_recv_error(sk, msg, len, addr_len);
1585 
1586 try_again:
1587         peeking = flags & MSG_PEEK;
1588         off = sk_peek_offset(sk, flags);
1589         skb = __skb_recv_udp(sk, flags, noblock, &peeked, &off, &err);
1590         if (!skb)
1591                 return err;
1592         if (ccs_socket_post_recvmsg_permission(sk, skb, flags))
1593                 return -EAGAIN; /* Hope less harmful than -EPERM. */
1594 
1595         ulen = udp_skb_len(skb);
1596         copied = len;
1597         if (copied > ulen - off)
1598                 copied = ulen - off;
1599         else if (copied < ulen)
1600                 msg->msg_flags |= MSG_TRUNC;
1601 
1602         /*
1603          * If checksum is needed at all, try to do it while copying the
1604          * data.  If the data is truncated, or if we only want a partial
1605          * coverage checksum (UDP-Lite), do it before the copy.
1606          */
1607 
1608         if (copied < ulen || peeking ||
1609             (is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
1610                 checksum_valid = udp_skb_csum_unnecessary(skb) ||
1611                                 !__udp_lib_checksum_complete(skb);
1612                 if (!checksum_valid)
1613                         goto csum_copy_err;
1614         }
1615 
1616         if (checksum_valid || udp_skb_csum_unnecessary(skb)) {
1617                 if (udp_skb_is_linear(skb))
1618                         err = copy_linear_skb(skb, copied, off, &msg->msg_iter);
1619                 else
1620                         err = skb_copy_datagram_msg(skb, off, msg, copied);
1621         } else {
1622                 err = skb_copy_and_csum_datagram_msg(skb, off, msg);
1623 
1624                 if (err == -EINVAL)
1625                         goto csum_copy_err;
1626         }
1627 
1628         if (unlikely(err)) {
1629                 if (!peeked) {
1630                         atomic_inc(&sk->sk_drops);
1631                         UDP_INC_STATS(sock_net(sk),
1632                                       UDP_MIB_INERRORS, is_udplite);
1633                 }
1634                 kfree_skb(skb);
1635                 return err;
1636         }
1637 
1638         if (!peeked)
1639                 UDP_INC_STATS(sock_net(sk),
1640                               UDP_MIB_INDATAGRAMS, is_udplite);
1641 
1642         sock_recv_ts_and_drops(msg, sk, skb);
1643 
1644         /* Copy the address. */
1645         if (sin) {
1646                 sin->sin_family = AF_INET;
1647                 sin->sin_port = udp_hdr(skb)->source;
1648                 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
1649                 memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
1650                 *addr_len = sizeof(*sin);
1651         }
1652         if (inet->cmsg_flags)
1653                 ip_cmsg_recv_offset(msg, sk, skb, sizeof(struct udphdr), off);
1654 
1655         err = copied;
1656         if (flags & MSG_TRUNC)
1657                 err = ulen;
1658 
1659         skb_consume_udp(sk, skb, peeking ? -err : err);
1660         return err;
1661 
1662 csum_copy_err:
1663         if (!__sk_queue_drop_skb(sk, &udp_sk(sk)->reader_queue, skb, flags,
1664                                  udp_skb_destructor)) {
1665                 UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
1666                 UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1667         }
1668         kfree_skb(skb);
1669 
1670         /* starting over for a new packet, but check if we need to yield */
1671         cond_resched();
1672         msg->msg_flags &= ~MSG_TRUNC;
1673         goto try_again;
1674 }
1675 
1676 int __udp_disconnect(struct sock *sk, int flags)
1677 {
1678         struct inet_sock *inet = inet_sk(sk);
1679         /*
1680          *      1003.1g - break association.
1681          */
1682 
1683         sk->sk_state = TCP_CLOSE;
1684         inet->inet_daddr = 0;
1685         inet->inet_dport = 0;
1686         sock_rps_reset_rxhash(sk);
1687         sk->sk_bound_dev_if = 0;
1688         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1689                 inet_reset_saddr(sk);
1690 
1691         if (!(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) {
1692                 sk->sk_prot->unhash(sk);
1693                 inet->inet_sport = 0;
1694         }
1695         sk_dst_reset(sk);
1696         return 0;
1697 }
1698 EXPORT_SYMBOL(__udp_disconnect);
1699 
1700 int udp_disconnect(struct sock *sk, int flags)
1701 {
1702         lock_sock(sk);
1703         __udp_disconnect(sk, flags);
1704         release_sock(sk);
1705         return 0;
1706 }
1707 EXPORT_SYMBOL(udp_disconnect);
1708 
1709 void udp_lib_unhash(struct sock *sk)
1710 {
1711         if (sk_hashed(sk)) {
1712                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
1713                 struct udp_hslot *hslot, *hslot2;
1714 
1715                 hslot  = udp_hashslot(udptable, sock_net(sk),
1716                                       udp_sk(sk)->udp_port_hash);
1717                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
1718 
1719                 spin_lock_bh(&hslot->lock);
1720                 if (rcu_access_pointer(sk->sk_reuseport_cb))
1721                         reuseport_detach_sock(sk);
1722                 if (sk_del_node_init_rcu(sk)) {
1723                         hslot->count--;
1724                         inet_sk(sk)->inet_num = 0;
1725                         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
1726 
1727                         spin_lock(&hslot2->lock);
1728                         hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
1729                         hslot2->count--;
1730                         spin_unlock(&hslot2->lock);
1731                 }
1732                 spin_unlock_bh(&hslot->lock);
1733         }
1734 }
1735 EXPORT_SYMBOL(udp_lib_unhash);
1736 
1737 /*
1738  * inet_rcv_saddr was changed, we must rehash secondary hash
1739  */
1740 void udp_lib_rehash(struct sock *sk, u16 newhash)
1741 {
1742         if (sk_hashed(sk)) {
1743                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
1744                 struct udp_hslot *hslot, *hslot2, *nhslot2;
1745 
1746                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
1747                 nhslot2 = udp_hashslot2(udptable, newhash);
1748                 udp_sk(sk)->udp_portaddr_hash = newhash;
1749 
1750                 if (hslot2 != nhslot2 ||
1751                     rcu_access_pointer(sk->sk_reuseport_cb)) {
1752                         hslot = udp_hashslot(udptable, sock_net(sk),
1753                                              udp_sk(sk)->udp_port_hash);
1754                         /* we must lock primary chain too */
1755                         spin_lock_bh(&hslot->lock);
1756                         if (rcu_access_pointer(sk->sk_reuseport_cb))
1757                                 reuseport_detach_sock(sk);
1758 
1759                         if (hslot2 != nhslot2) {
1760                                 spin_lock(&hslot2->lock);
1761                                 hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
1762                                 hslot2->count--;
1763                                 spin_unlock(&hslot2->lock);
1764 
1765                                 spin_lock(&nhslot2->lock);
1766                                 hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
1767                                                          &nhslot2->head);
1768                                 nhslot2->count++;
1769                                 spin_unlock(&nhslot2->lock);
1770                         }
1771 
1772                         spin_unlock_bh(&hslot->lock);
1773                 }
1774         }
1775 }
1776 EXPORT_SYMBOL(udp_lib_rehash);
1777 
1778 static void udp_v4_rehash(struct sock *sk)
1779 {
1780         u16 new_hash = udp4_portaddr_hash(sock_net(sk),
1781                                           inet_sk(sk)->inet_rcv_saddr,
1782                                           inet_sk(sk)->inet_num);
1783         udp_lib_rehash(sk, new_hash);
1784 }
1785 
1786 static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
1787 {
1788         int rc;
1789 
1790         if (inet_sk(sk)->inet_daddr) {
1791                 sock_rps_save_rxhash(sk, skb);
1792                 sk_mark_napi_id(sk, skb);
1793                 sk_incoming_cpu_update(sk);
1794         } else {
1795                 sk_mark_napi_id_once(sk, skb);
1796         }
1797 
1798         rc = __udp_enqueue_schedule_skb(sk, skb);
1799         if (rc < 0) {
1800                 int is_udplite = IS_UDPLITE(sk);
1801 
1802                 /* Note that an ENOMEM error is charged twice */
1803                 if (rc == -ENOMEM)
1804                         UDP_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS,
1805                                         is_udplite);
1806                 UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1807                 kfree_skb(skb);
1808                 trace_udp_fail_queue_rcv_skb(rc, sk);
1809                 return -1;
1810         }
1811 
1812         return 0;
1813 }
1814 
1815 static struct static_key udp_encap_needed __read_mostly;
1816 void udp_encap_enable(void)
1817 {
1818         static_key_enable(&udp_encap_needed);
1819 }
1820 EXPORT_SYMBOL(udp_encap_enable);
1821 
1822 /* returns:
1823  *  -1: error
1824  *   0: success
1825  *  >0: "udp encap" protocol resubmission
1826  *
1827  * Note that in the success and error cases, the skb is assumed to
1828  * have either been requeued or freed.
1829  */
1830 static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
1831 {
1832         struct udp_sock *up = udp_sk(sk);
1833         int is_udplite = IS_UDPLITE(sk);
1834 
1835         /*
1836          *      Charge it to the socket, dropping if the queue is full.
1837          */
1838         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1839                 goto drop;
1840         nf_reset(skb);
1841 
1842         if (static_key_false(&udp_encap_needed) && up->encap_type) {
1843                 int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
1844 
1845                 /*
1846                  * This is an encapsulation socket so pass the skb to
1847                  * the socket's udp_encap_rcv() hook. Otherwise, just
1848                  * fall through and pass this up the UDP socket.
1849                  * up->encap_rcv() returns the following value:
1850                  * =0 if skb was successfully passed to the encap
1851                  *    handler or was discarded by it.
1852                  * >0 if skb should be passed on to UDP.
1853                  * <0 if skb should be resubmitted as proto -N
1854                  */
1855 
1856                 /* if we're overly short, let UDP handle it */
1857                 encap_rcv = READ_ONCE(up->encap_rcv);
1858                 if (encap_rcv) {
1859                         int ret;
1860 
1861                         /* Verify checksum before giving to encap */
1862                         if (udp_lib_checksum_complete(skb))
1863                                 goto csum_error;
1864 
1865                         ret = encap_rcv(sk, skb);
1866                         if (ret <= 0) {
1867                                 __UDP_INC_STATS(sock_net(sk),
1868                                                 UDP_MIB_INDATAGRAMS,
1869                                                 is_udplite);
1870                                 return -ret;
1871                         }
1872                 }
1873 
1874                 /* FALLTHROUGH -- it's a UDP Packet */
1875         }
1876 
1877         /*
1878          *      UDP-Lite specific tests, ignored on UDP sockets
1879          */
1880         if ((is_udplite & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
1881 
1882                 /*
1883                  * MIB statistics other than incrementing the error count are
1884                  * disabled for the following two types of errors: these depend
1885                  * on the application settings, not on the functioning of the
1886                  * protocol stack as such.
1887                  *
1888                  * RFC 3828 here recommends (sec 3.3): "There should also be a
1889                  * way ... to ... at least let the receiving application block
1890                  * delivery of packets with coverage values less than a value
1891                  * provided by the application."
1892                  */
1893                 if (up->pcrlen == 0) {          /* full coverage was set  */
1894                         net_dbg_ratelimited("UDPLite: partial coverage %d while full coverage %d requested\n",
1895                                             UDP_SKB_CB(skb)->cscov, skb->len);
1896                         goto drop;
1897                 }
1898                 /* The next case involves violating the min. coverage requested
1899                  * by the receiver. This is subtle: if receiver wants x and x is
1900                  * greater than the buffersize/MTU then receiver will complain
1901                  * that it wants x while sender emits packets of smaller size y.
1902                  * Therefore the above ...()->partial_cov statement is essential.
1903                  */
1904                 if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
1905                         net_dbg_ratelimited("UDPLite: coverage %d too small, need min %d\n",
1906                                             UDP_SKB_CB(skb)->cscov, up->pcrlen);
1907                         goto drop;
1908                 }
1909         }
1910 
1911         prefetch(&sk->sk_rmem_alloc);
1912         if (rcu_access_pointer(sk->sk_filter) &&
1913             udp_lib_checksum_complete(skb))
1914                         goto csum_error;
1915 
1916         if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr)))
1917                 goto drop;
1918 
1919         udp_csum_pull_header(skb);
1920 
1921         ipv4_pktinfo_prepare(sk, skb);
1922         return __udp_queue_rcv_skb(sk, skb);
1923 
1924 csum_error:
1925         __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
1926 drop:
1927         __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1928         atomic_inc(&sk->sk_drops);
1929         kfree_skb(skb);
1930         return -1;
1931 }
1932 
1933 /* For TCP sockets, sk_rx_dst is protected by socket lock
1934  * For UDP, we use xchg() to guard against concurrent changes.
1935  */
1936 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
1937 {
1938         struct dst_entry *old;
1939 
1940         if (dst_hold_safe(dst)) {
1941                 old = xchg(&sk->sk_rx_dst, dst);
1942                 dst_release(old);
1943                 return old != dst;
1944         }
1945         return false;
1946 }
1947 EXPORT_SYMBOL(udp_sk_rx_dst_set);
1948 
1949 /*
1950  *      Multicasts and broadcasts go to each listener.
1951  *
1952  *      Note: called only from the BH handler context.
1953  */
1954 static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
1955                                     struct udphdr  *uh,
1956                                     __be32 saddr, __be32 daddr,
1957                                     struct udp_table *udptable,
1958                                     int proto)
1959 {
1960         struct sock *sk, *first = NULL;
1961         unsigned short hnum = ntohs(uh->dest);
1962         struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum);
1963         unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
1964         unsigned int offset = offsetof(typeof(*sk), sk_node);
1965         int dif = skb->dev->ifindex;
1966         int sdif = inet_sdif(skb);
1967         struct hlist_node *node;
1968         struct sk_buff *nskb;
1969 
1970         if (use_hash2) {
1971                 hash2_any = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum) &
1972                             udptable->mask;
1973                 hash2 = udp4_portaddr_hash(net, daddr, hnum) & udptable->mask;
1974 start_lookup:
1975                 hslot = &udptable->hash2[hash2];
1976                 offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node);
1977         }
1978 
1979         sk_for_each_entry_offset_rcu(sk, node, &hslot->head, offset) {
1980                 if (!__udp_is_mcast_sock(net, sk, uh->dest, daddr,
1981                                          uh->source, saddr, dif, sdif, hnum))
1982                         continue;
1983 
1984                 if (!first) {
1985                         first = sk;
1986                         continue;
1987                 }
1988                 nskb = skb_clone(skb, GFP_ATOMIC);
1989 
1990                 if (unlikely(!nskb)) {
1991                         atomic_inc(&sk->sk_drops);
1992                         __UDP_INC_STATS(net, UDP_MIB_RCVBUFERRORS,
1993                                         IS_UDPLITE(sk));
1994                         __UDP_INC_STATS(net, UDP_MIB_INERRORS,
1995                                         IS_UDPLITE(sk));
1996                         continue;
1997                 }
1998                 if (udp_queue_rcv_skb(sk, nskb) > 0)
1999                         consume_skb(nskb);
2000         }
2001 
2002         /* Also lookup *:port if we are using hash2 and haven't done so yet. */
2003         if (use_hash2 && hash2 != hash2_any) {
2004                 hash2 = hash2_any;
2005                 goto start_lookup;
2006         }
2007 
2008         if (first) {
2009                 if (udp_queue_rcv_skb(first, skb) > 0)
2010                         consume_skb(skb);
2011         } else {
2012                 kfree_skb(skb);
2013                 __UDP_INC_STATS(net, UDP_MIB_IGNOREDMULTI,
2014                                 proto == IPPROTO_UDPLITE);
2015         }
2016         return 0;
2017 }
2018 
2019 /* Initialize UDP checksum. If exited with zero value (success),
2020  * CHECKSUM_UNNECESSARY means, that no more checks are required.
2021  * Otherwise, csum completion requires chacksumming packet body,
2022  * including udp header and folding it to skb->csum.
2023  */
2024 static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,
2025                                  int proto)
2026 {
2027         int err;
2028 
2029         UDP_SKB_CB(skb)->partial_cov = 0;
2030         UDP_SKB_CB(skb)->cscov = skb->len;
2031 
2032         if (proto == IPPROTO_UDPLITE) {
2033                 err = udplite_checksum_init(skb, uh);
2034                 if (err)
2035                         return err;
2036 
2037                 if (UDP_SKB_CB(skb)->partial_cov) {
2038                         skb->csum = inet_compute_pseudo(skb, proto);
2039                         return 0;
2040                 }
2041         }
2042 
2043         /* Note, we are only interested in != 0 or == 0, thus the
2044          * force to int.
2045          */
2046         return (__force int)skb_checksum_init_zero_check(skb, proto, uh->check,
2047                                                          inet_compute_pseudo);
2048 }
2049 
2050 /*
2051  *      All we need to do is get the socket, and then do a checksum.
2052  */
2053 
2054 int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
2055                    int proto)
2056 {
2057         struct sock *sk;
2058         struct udphdr *uh;
2059         unsigned short ulen;
2060         struct rtable *rt = skb_rtable(skb);
2061         __be32 saddr, daddr;
2062         struct net *net = dev_net(skb->dev);
2063 
2064         /*
2065          *  Validate the packet.
2066          */
2067         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
2068                 goto drop;              /* No space for header. */
2069 
2070         uh   = udp_hdr(skb);
2071         ulen = ntohs(uh->len);
2072         saddr = ip_hdr(skb)->saddr;
2073         daddr = ip_hdr(skb)->daddr;
2074 
2075         if (ulen > skb->len)
2076                 goto short_packet;
2077 
2078         if (proto == IPPROTO_UDP) {
2079                 /* UDP validates ulen. */
2080                 if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen))
2081                         goto short_packet;
2082                 uh = udp_hdr(skb);
2083         }
2084 
2085         if (udp4_csum_init(skb, uh, proto))
2086                 goto csum_error;
2087 
2088         sk = skb_steal_sock(skb);
2089         if (sk) {
2090                 struct dst_entry *dst = skb_dst(skb);
2091                 int ret;
2092 
2093                 if (unlikely(sk->sk_rx_dst != dst))
2094                         udp_sk_rx_dst_set(sk, dst);
2095 
2096                 ret = udp_queue_rcv_skb(sk, skb);
2097                 sock_put(sk);
2098                 /* a return value > 0 means to resubmit the input, but
2099                  * it wants the return to be -protocol, or 0
2100                  */
2101                 if (ret > 0)
2102                         return -ret;
2103                 return 0;
2104         }
2105 
2106         if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
2107                 return __udp4_lib_mcast_deliver(net, skb, uh,
2108                                                 saddr, daddr, udptable, proto);
2109 
2110         sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
2111         if (sk) {
2112                 int ret;
2113 
2114                 if (inet_get_convert_csum(sk) && uh->check && !IS_UDPLITE(sk))
2115                         skb_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
2116                                                  inet_compute_pseudo);
2117 
2118                 ret = udp_queue_rcv_skb(sk, skb);
2119 
2120                 /* a return value > 0 means to resubmit the input, but
2121                  * it wants the return to be -protocol, or 0
2122                  */
2123                 if (ret > 0)
2124                         return -ret;
2125                 return 0;
2126         }
2127 
2128         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
2129                 goto drop;
2130         nf_reset(skb);
2131 
2132         /* No socket. Drop packet silently, if checksum is wrong */
2133         if (udp_lib_checksum_complete(skb))
2134                 goto csum_error;
2135 
2136         __UDP_INC_STATS(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
2137         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
2138 
2139         /*
2140          * Hmm.  We got an UDP packet to a port to which we
2141          * don't wanna listen.  Ignore it.
2142          */
2143         kfree_skb(skb);
2144         return 0;
2145 
2146 short_packet:
2147         net_dbg_ratelimited("UDP%s: short packet: From %pI4:%u %d/%d to %pI4:%u\n",
2148                             proto == IPPROTO_UDPLITE ? "Lite" : "",
2149                             &saddr, ntohs(uh->source),
2150                             ulen, skb->len,
2151                             &daddr, ntohs(uh->dest));
2152         goto drop;
2153 
2154 csum_error:
2155         /*
2156          * RFC1122: OK.  Discards the bad packet silently (as far as
2157          * the network is concerned, anyway) as per 4.1.3.4 (MUST).
2158          */
2159         net_dbg_ratelimited("UDP%s: bad checksum. From %pI4:%u to %pI4:%u ulen %d\n",
2160                             proto == IPPROTO_UDPLITE ? "Lite" : "",
2161                             &saddr, ntohs(uh->source), &daddr, ntohs(uh->dest),
2162                             ulen);
2163         __UDP_INC_STATS(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE);
2164 drop:
2165         __UDP_INC_STATS(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
2166         kfree_skb(skb);
2167         return 0;
2168 }
2169 
2170 /* We can only early demux multicast if there is a single matching socket.
2171  * If more than one socket found returns NULL
2172  */
2173 static struct sock *__udp4_lib_mcast_demux_lookup(struct net *net,
2174                                                   __be16 loc_port, __be32 loc_addr,
2175                                                   __be16 rmt_port, __be32 rmt_addr,
2176                                                   int dif, int sdif)
2177 {
2178         struct sock *sk, *result;
2179         unsigned short hnum = ntohs(loc_port);
2180         unsigned int slot = udp_hashfn(net, hnum, udp_table.mask);
2181         struct udp_hslot *hslot = &udp_table.hash[slot];
2182 
2183         /* Do not bother scanning a too big list */
2184         if (hslot->count > 10)
2185                 return NULL;
2186 
2187         result = NULL;
2188         sk_for_each_rcu(sk, &hslot->head) {
2189                 if (__udp_is_mcast_sock(net, sk, loc_port, loc_addr,
2190                                         rmt_port, rmt_addr, dif, sdif, hnum)) {
2191                         if (result)
2192                                 return NULL;
2193                         result = sk;
2194                 }
2195         }
2196 
2197         return result;
2198 }
2199 
2200 /* For unicast we should only early demux connected sockets or we can
2201  * break forwarding setups.  The chains here can be long so only check
2202  * if the first socket is an exact match and if not move on.
2203  */
2204 static struct sock *__udp4_lib_demux_lookup(struct net *net,
2205                                             __be16 loc_port, __be32 loc_addr,
2206                                             __be16 rmt_port, __be32 rmt_addr,
2207                                             int dif, int sdif)
2208 {
2209         unsigned short hnum = ntohs(loc_port);
2210         unsigned int hash2 = udp4_portaddr_hash(net, loc_addr, hnum);
2211         unsigned int slot2 = hash2 & udp_table.mask;
2212         struct udp_hslot *hslot2 = &udp_table.hash2[slot2];
2213         INET_ADDR_COOKIE(acookie, rmt_addr, loc_addr);
2214         const __portpair ports = INET_COMBINED_PORTS(rmt_port, hnum);
2215         struct sock *sk;
2216 
2217         udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
2218                 if (INET_MATCH(sk, net, acookie, rmt_addr,
2219                                loc_addr, ports, dif, sdif))
2220                         return sk;
2221                 /* Only check first socket in chain */
2222                 break;
2223         }
2224         return NULL;
2225 }
2226 
2227 int udp_v4_early_demux(struct sk_buff *skb)
2228 {
2229         struct net *net = dev_net(skb->dev);
2230         struct in_device *in_dev = NULL;
2231         const struct iphdr *iph;
2232         const struct udphdr *uh;
2233         struct sock *sk = NULL;
2234         struct dst_entry *dst;
2235         int dif = skb->dev->ifindex;
2236         int sdif = inet_sdif(skb);
2237         int ours;
2238 
2239         /* validate the packet */
2240         if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr)))
2241                 return 0;
2242 
2243         iph = ip_hdr(skb);
2244         uh = udp_hdr(skb);
2245 
2246         if (skb->pkt_type == PACKET_MULTICAST) {
2247                 in_dev = __in_dev_get_rcu(skb->dev);
2248 
2249                 if (!in_dev)
2250                         return 0;
2251 
2252                 ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
2253                                        iph->protocol);
2254                 if (!ours)
2255                         return 0;
2256 
2257                 sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr,
2258                                                    uh->source, iph->saddr,
2259                                                    dif, sdif);
2260         } else if (skb->pkt_type == PACKET_HOST) {
2261                 sk = __udp4_lib_demux_lookup(net, uh->dest, iph->daddr,
2262                                              uh->source, iph->saddr, dif, sdif);
2263         }
2264 
2265         if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
2266                 return 0;
2267 
2268         skb->sk = sk;
2269         skb->destructor = sock_efree;
2270         dst = READ_ONCE(sk->sk_rx_dst);
2271 
2272         if (dst)
2273                 dst = dst_check(dst, 0);
2274         if (dst) {
2275                 u32 itag = 0;
2276 
2277                 /* set noref for now.
2278                  * any place which wants to hold dst has to call
2279                  * dst_hold_safe()
2280                  */
2281                 skb_dst_set_noref(skb, dst);
2282 
2283                 /* for unconnected multicast sockets we need to validate
2284                  * the source on each packet
2285                  */
2286                 if (!inet_sk(sk)->inet_daddr && in_dev)
2287                         return ip_mc_validate_source(skb, iph->daddr,
2288                                                      iph->saddr, iph->tos,
2289                                                      skb->dev, in_dev, &itag);
2290         }
2291         return 0;
2292 }
2293 
2294 int udp_rcv(struct sk_buff *skb)
2295 {
2296         return __udp4_lib_rcv(skb, &udp_table, IPPROTO_UDP);
2297 }
2298 
2299 void udp_destroy_sock(struct sock *sk)
2300 {
2301         struct udp_sock *up = udp_sk(sk);
2302         bool slow = lock_sock_fast(sk);
2303         udp_flush_pending_frames(sk);
2304         unlock_sock_fast(sk, slow);
2305         if (static_key_false(&udp_encap_needed) && up->encap_type) {
2306                 void (*encap_destroy)(struct sock *sk);
2307                 encap_destroy = READ_ONCE(up->encap_destroy);
2308                 if (encap_destroy)
2309                         encap_destroy(sk);
2310         }
2311 }
2312 
2313 /*
2314  *      Socket option code for UDP
2315  */
2316 int udp_lib_setsockopt(struct sock *sk, int level, int optname,
2317                        char __user *optval, unsigned int optlen,
2318                        int (*push_pending_frames)(struct sock *))
2319 {
2320         struct udp_sock *up = udp_sk(sk);
2321         int val, valbool;
2322         int err = 0;
2323         int is_udplite = IS_UDPLITE(sk);
2324 
2325         if (optlen < sizeof(int))
2326                 return -EINVAL;
2327 
2328         if (get_user(val, (int __user *)optval))
2329                 return -EFAULT;
2330 
2331         valbool = val ? 1 : 0;
2332 
2333         switch (optname) {
2334         case UDP_CORK:
2335                 if (val != 0) {
2336                         up->corkflag = 1;
2337                 } else {
2338                         up->corkflag = 0;
2339                         lock_sock(sk);
2340                         push_pending_frames(sk);
2341                         release_sock(sk);
2342                 }
2343                 break;
2344 
2345         case UDP_ENCAP:
2346                 switch (val) {
2347                 case 0:
2348                 case UDP_ENCAP_ESPINUDP:
2349                 case UDP_ENCAP_ESPINUDP_NON_IKE:
2350                         up->encap_rcv = xfrm4_udp_encap_rcv;
2351                         /* FALLTHROUGH */
2352                 case UDP_ENCAP_L2TPINUDP:
2353                         up->encap_type = val;
2354                         udp_encap_enable();
2355                         break;
2356                 default:
2357                         err = -ENOPROTOOPT;
2358                         break;
2359                 }
2360                 break;
2361 
2362         case UDP_NO_CHECK6_TX:
2363                 up->no_check6_tx = valbool;
2364                 break;
2365 
2366         case UDP_NO_CHECK6_RX:
2367                 up->no_check6_rx = valbool;
2368                 break;
2369 
2370         /*
2371          *      UDP-Lite's partial checksum coverage (RFC 3828).
2372          */
2373         /* The sender sets actual checksum coverage length via this option.
2374          * The case coverage > packet length is handled by send module. */
2375         case UDPLITE_SEND_CSCOV:
2376                 if (!is_udplite)         /* Disable the option on UDP sockets */
2377                         return -ENOPROTOOPT;
2378                 if (val != 0 && val < 8) /* Illegal coverage: use default (8) */
2379                         val = 8;
2380                 else if (val > USHRT_MAX)
2381                         val = USHRT_MAX;
2382                 up->pcslen = val;
2383                 up->pcflag |= UDPLITE_SEND_CC;
2384                 break;
2385 
2386         /* The receiver specifies a minimum checksum coverage value. To make
2387          * sense, this should be set to at least 8 (as done below). If zero is
2388          * used, this again means full checksum coverage.                     */
2389         case UDPLITE_RECV_CSCOV:
2390                 if (!is_udplite)         /* Disable the option on UDP sockets */
2391                         return -ENOPROTOOPT;
2392                 if (val != 0 && val < 8) /* Avoid silly minimal values.       */
2393                         val = 8;
2394                 else if (val > USHRT_MAX)
2395                         val = USHRT_MAX;
2396                 up->pcrlen = val;
2397                 up->pcflag |= UDPLITE_RECV_CC;
2398                 break;
2399 
2400         default:
2401                 err = -ENOPROTOOPT;
2402                 break;
2403         }
2404 
2405         return err;
2406 }
2407 EXPORT_SYMBOL(udp_lib_setsockopt);
2408 
2409 int udp_setsockopt(struct sock *sk, int level, int optname,
2410                    char __user *optval, unsigned int optlen)
2411 {
2412         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2413                 return udp_lib_setsockopt(sk, level, optname, optval, optlen,
2414                                           udp_push_pending_frames);
2415         return ip_setsockopt(sk, level, optname, optval, optlen);
2416 }
2417 
2418 #ifdef CONFIG_COMPAT
2419 int compat_udp_setsockopt(struct sock *sk, int level, int optname,
2420                           char __user *optval, unsigned int optlen)
2421 {
2422         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2423                 return udp_lib_setsockopt(sk, level, optname, optval, optlen,
2424                                           udp_push_pending_frames);
2425         return compat_ip_setsockopt(sk, level, optname, optval, optlen);
2426 }
2427 #endif
2428 
2429 int udp_lib_getsockopt(struct sock *sk, int level, int optname,
2430                        char __user *optval, int __user *optlen)
2431 {
2432         struct udp_sock *up = udp_sk(sk);
2433         int val, len;
2434 
2435         if (get_user(len, optlen))
2436                 return -EFAULT;
2437 
2438         len = min_t(unsigned int, len, sizeof(int));
2439 
2440         if (len < 0)
2441                 return -EINVAL;
2442 
2443         switch (optname) {
2444         case UDP_CORK:
2445                 val = up->corkflag;
2446                 break;
2447 
2448         case UDP_ENCAP:
2449                 val = up->encap_type;
2450                 break;
2451 
2452         case UDP_NO_CHECK6_TX:
2453                 val = up->no_check6_tx;
2454                 break;
2455 
2456         case UDP_NO_CHECK6_RX:
2457                 val = up->no_check6_rx;
2458                 break;
2459 
2460         /* The following two cannot be changed on UDP sockets, the return is
2461          * always 0 (which corresponds to the full checksum coverage of UDP). */
2462         case UDPLITE_SEND_CSCOV:
2463                 val = up->pcslen;
2464                 break;
2465 
2466         case UDPLITE_RECV_CSCOV:
2467                 val = up->pcrlen;
2468                 break;
2469 
2470         default:
2471                 return -ENOPROTOOPT;
2472         }
2473 
2474         if (put_user(len, optlen))
2475                 return -EFAULT;
2476         if (copy_to_user(optval, &val, len))
2477                 return -EFAULT;
2478         return 0;
2479 }
2480 EXPORT_SYMBOL(udp_lib_getsockopt);
2481 
2482 int udp_getsockopt(struct sock *sk, int level, int optname,
2483                    char __user *optval, int __user *optlen)
2484 {
2485         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2486                 return udp_lib_getsockopt(sk, level, optname, optval, optlen);
2487         return ip_getsockopt(sk, level, optname, optval, optlen);
2488 }
2489 
2490 #ifdef CONFIG_COMPAT
2491 int compat_udp_getsockopt(struct sock *sk, int level, int optname,
2492                                  char __user *optval, int __user *optlen)
2493 {
2494         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2495                 return udp_lib_getsockopt(sk, level, optname, optval, optlen);
2496         return compat_ip_getsockopt(sk, level, optname, optval, optlen);
2497 }
2498 #endif
2499 /**
2500  *      udp_poll - wait for a UDP event.
2501  *      @file - file struct
2502  *      @sock - socket
2503  *      @wait - poll table
2504  *
2505  *      This is same as datagram poll, except for the special case of
2506  *      blocking sockets. If application is using a blocking fd
2507  *      and a packet with checksum error is in the queue;
2508  *      then it could get return from select indicating data available
2509  *      but then block when reading it. Add special case code
2510  *      to work around these arguably broken applications.
2511  */
2512 unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
2513 {
2514         unsigned int mask = datagram_poll(file, sock, wait);
2515         struct sock *sk = sock->sk;
2516 
2517         if (!skb_queue_empty(&udp_sk(sk)->reader_queue))
2518                 mask |= POLLIN | POLLRDNORM;
2519 
2520         sock_rps_record_flow(sk);
2521 
2522         /* Check for false positives due to checksum errors */
2523         if ((mask & POLLRDNORM) && !(file->f_flags & O_NONBLOCK) &&
2524             !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1)
2525                 mask &= ~(POLLIN | POLLRDNORM);
2526 
2527         return mask;
2528 
2529 }
2530 EXPORT_SYMBOL(udp_poll);
2531 
2532 int udp_abort(struct sock *sk, int err)
2533 {
2534         lock_sock(sk);
2535 
2536         sk->sk_err = err;
2537         sk->sk_error_report(sk);
2538         __udp_disconnect(sk, 0);
2539 
2540         release_sock(sk);
2541 
2542         return 0;
2543 }
2544 EXPORT_SYMBOL_GPL(udp_abort);
2545 
2546 struct proto udp_prot = {
2547         .name              = "UDP",
2548         .owner             = THIS_MODULE,
2549         .close             = udp_lib_close,
2550         .connect           = ip4_datagram_connect,
2551         .disconnect        = udp_disconnect,
2552         .ioctl             = udp_ioctl,
2553         .init              = udp_init_sock,
2554         .destroy           = udp_destroy_sock,
2555         .setsockopt        = udp_setsockopt,
2556         .getsockopt        = udp_getsockopt,
2557         .sendmsg           = udp_sendmsg,
2558         .recvmsg           = udp_recvmsg,
2559         .sendpage          = udp_sendpage,
2560         .release_cb        = ip4_datagram_release_cb,
2561         .hash              = udp_lib_hash,
2562         .unhash            = udp_lib_unhash,
2563         .rehash            = udp_v4_rehash,
2564         .get_port          = udp_v4_get_port,
2565         .memory_allocated  = &udp_memory_allocated,
2566         .sysctl_mem        = sysctl_udp_mem,
2567         .sysctl_wmem       = &sysctl_udp_wmem_min,
2568         .sysctl_rmem       = &sysctl_udp_rmem_min,
2569         .obj_size          = sizeof(struct udp_sock),
2570         .h.udp_table       = &udp_table,
2571 #ifdef CONFIG_COMPAT
2572         .compat_setsockopt = compat_udp_setsockopt,
2573         .compat_getsockopt = compat_udp_getsockopt,
2574 #endif
2575         .diag_destroy      = udp_abort,
2576 };
2577 EXPORT_SYMBOL(udp_prot);
2578 
2579 /* ------------------------------------------------------------------------ */
2580 #ifdef CONFIG_PROC_FS
2581 
2582 static struct sock *udp_get_first(struct seq_file *seq, int start)
2583 {
2584         struct sock *sk;
2585         struct udp_iter_state *state = seq->private;
2586         struct net *net = seq_file_net(seq);
2587 
2588         for (state->bucket = start; state->bucket <= state->udp_table->mask;
2589              ++state->bucket) {
2590                 struct udp_hslot *hslot = &state->udp_table->hash[state->bucket];
2591 
2592                 if (hlist_empty(&hslot->head))
2593                         continue;
2594 
2595                 spin_lock_bh(&hslot->lock);
2596                 sk_for_each(sk, &hslot->head) {
2597                         if (!net_eq(sock_net(sk), net))
2598                                 continue;
2599                         if (sk->sk_family == state->family)
2600                                 goto found;
2601                 }
2602                 spin_unlock_bh(&hslot->lock);
2603         }
2604         sk = NULL;
2605 found:
2606         return sk;
2607 }
2608 
2609 static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
2610 {
2611         struct udp_iter_state *state = seq->private;
2612         struct net *net = seq_file_net(seq);
2613 
2614         do {
2615                 sk = sk_next(sk);
2616         } while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != state->family));
2617 
2618         if (!sk) {
2619                 if (state->bucket <= state->udp_table->mask)
2620                         spin_unlock_bh(&state->udp_table->hash[state->bucket].lock);
2621                 return udp_get_first(seq, state->bucket + 1);
2622         }
2623         return sk;
2624 }
2625 
2626 static struct sock *udp_get_idx(struct seq_file *seq, loff_t pos)
2627 {
2628         struct sock *sk = udp_get_first(seq, 0);
2629 
2630         if (sk)
2631                 while (pos && (sk = udp_get_next(seq, sk)) != NULL)
2632                         --pos;
2633         return pos ? NULL : sk;
2634 }
2635 
2636 static void *udp_seq_start(struct seq_file *seq, loff_t *pos)
2637 {
2638         struct udp_iter_state *state = seq->private;
2639         state->bucket = MAX_UDP_PORTS;
2640 
2641         return *pos ? udp_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
2642 }
2643 
2644 static void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2645 {
2646         struct sock *sk;
2647 
2648         if (v == SEQ_START_TOKEN)
2649                 sk = udp_get_idx(seq, 0);
2650         else
2651                 sk = udp_get_next(seq, v);
2652 
2653         ++*pos;
2654         return sk;
2655 }
2656 
2657 static void udp_seq_stop(struct seq_file *seq, void *v)
2658 {
2659         struct udp_iter_state *state = seq->private;
2660 
2661         if (state->bucket <= state->udp_table->mask)
2662                 spin_unlock_bh(&state->udp_table->hash[state->bucket].lock);
2663 }
2664 
2665 int udp_seq_open(struct inode *inode, struct file *file)
2666 {
2667         struct udp_seq_afinfo *afinfo = PDE_DATA(inode);
2668         struct udp_iter_state *s;
2669         int err;
2670 
2671         err = seq_open_net(inode, file, &afinfo->seq_ops,
2672                            sizeof(struct udp_iter_state));
2673         if (err < 0)
2674                 return err;
2675 
2676         s = ((struct seq_file *)file->private_data)->private;
2677         s->family               = afinfo->family;
2678         s->udp_table            = afinfo->udp_table;
2679         return err;
2680 }
2681 EXPORT_SYMBOL(udp_seq_open);
2682 
2683 /* ------------------------------------------------------------------------ */
2684 int udp_proc_register(struct net *net, struct udp_seq_afinfo *afinfo)
2685 {
2686         struct proc_dir_entry *p;
2687         int rc = 0;
2688 
2689         afinfo->seq_ops.start           = udp_seq_start;
2690         afinfo->seq_ops.next            = udp_seq_next;
2691         afinfo->seq_ops.stop            = udp_seq_stop;
2692 
2693         p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2694                              afinfo->seq_fops, afinfo);
2695         if (!p)
2696                 rc = -ENOMEM;
2697         return rc;
2698 }
2699 EXPORT_SYMBOL(udp_proc_register);
2700 
2701 void udp_proc_unregister(struct net *net, struct udp_seq_afinfo *afinfo)
2702 {
2703         remove_proc_entry(afinfo->name, net->proc_net);
2704 }
2705 EXPORT_SYMBOL(udp_proc_unregister);
2706 
2707 /* ------------------------------------------------------------------------ */
2708 static void udp4_format_sock(struct sock *sp, struct seq_file *f,
2709                 int bucket)
2710 {
2711         struct inet_sock *inet = inet_sk(sp);
2712         __be32 dest = inet->inet_daddr;
2713         __be32 src  = inet->inet_rcv_saddr;
2714         __u16 destp       = ntohs(inet->inet_dport);
2715         __u16 srcp        = ntohs(inet->inet_sport);
2716 
2717         seq_printf(f, "%5d: %08X:%04X %08X:%04X"
2718                 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
2719                 bucket, src, srcp, dest, destp, sp->sk_state,
2720                 sk_wmem_alloc_get(sp),
2721                 sk_rmem_alloc_get(sp),
2722                 0, 0L, 0,
2723                 from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
2724                 0, sock_i_ino(sp),
2725                 refcount_read(&sp->sk_refcnt), sp,
2726                 atomic_read(&sp->sk_drops));
2727 }
2728 
2729 int udp4_seq_show(struct seq_file *seq, void *v)
2730 {
2731         seq_setwidth(seq, 127);
2732         if (v == SEQ_START_TOKEN)
2733                 seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
2734                            "rx_queue tr tm->when retrnsmt   uid  timeout "
2735                            "inode ref pointer drops");
2736         else {
2737                 struct udp_iter_state *state = seq->private;
2738 
2739                 udp4_format_sock(v, seq, state->bucket);
2740         }
2741         seq_pad(seq, '\n');
2742         return 0;
2743 }
2744 
2745 static const struct file_operations udp_afinfo_seq_fops = {
2746         .owner    = THIS_MODULE,
2747         .open     = udp_seq_open,
2748         .read     = seq_read,
2749         .llseek   = seq_lseek,
2750         .release  = seq_release_net
2751 };
2752 
2753 /* ------------------------------------------------------------------------ */
2754 static struct udp_seq_afinfo udp4_seq_afinfo = {
2755         .name           = "udp",
2756         .family         = AF_INET,
2757         .udp_table      = &udp_table,
2758         .seq_fops       = &udp_afinfo_seq_fops,
2759         .seq_ops        = {
2760                 .show           = udp4_seq_show,
2761         },
2762 };
2763 
2764 static int __net_init udp4_proc_init_net(struct net *net)
2765 {
2766         return udp_proc_register(net, &udp4_seq_afinfo);
2767 }
2768 
2769 static void __net_exit udp4_proc_exit_net(struct net *net)
2770 {
2771         udp_proc_unregister(net, &udp4_seq_afinfo);
2772 }
2773 
2774 static struct pernet_operations udp4_net_ops = {
2775         .init = udp4_proc_init_net,
2776         .exit = udp4_proc_exit_net,
2777 };
2778 
2779 int __init udp4_proc_init(void)
2780 {
2781         return register_pernet_subsys(&udp4_net_ops);
2782 }
2783 
2784 void udp4_proc_exit(void)
2785 {
2786         unregister_pernet_subsys(&udp4_net_ops);
2787 }
2788 #endif /* CONFIG_PROC_FS */
2789 
2790 static __initdata unsigned long uhash_entries;
2791 static int __init set_uhash_entries(char *str)
2792 {
2793         ssize_t ret;
2794 
2795         if (!str)
2796                 return 0;
2797 
2798         ret = kstrtoul(str, 0, &uhash_entries);
2799         if (ret)
2800                 return 0;
2801 
2802         if (uhash_entries && uhash_entries < UDP_HTABLE_SIZE_MIN)
2803                 uhash_entries = UDP_HTABLE_SIZE_MIN;
2804         return 1;
2805 }
2806 __setup("uhash_entries=", set_uhash_entries);
2807 
2808 void __init udp_table_init(struct udp_table *table, const char *name)
2809 {
2810         unsigned int i;
2811 
2812         table->hash = alloc_large_system_hash(name,
2813                                               2 * sizeof(struct udp_hslot),
2814                                               uhash_entries,
2815                                               21, /* one slot per 2 MB */
2816                                               0,
2817                                               &table->log,
2818                                               &table->mask,
2819                                               UDP_HTABLE_SIZE_MIN,
2820                                               64 * 1024);
2821 
2822         table->hash2 = table->hash + (table->mask + 1);
2823         for (i = 0; i <= table->mask; i++) {
2824                 INIT_HLIST_HEAD(&table->hash[i].head);
2825                 table->hash[i].count = 0;
2826                 spin_lock_init(&table->hash[i].lock);
2827         }
2828         for (i = 0; i <= table->mask; i++) {
2829                 INIT_HLIST_HEAD(&table->hash2[i].head);
2830                 table->hash2[i].count = 0;
2831                 spin_lock_init(&table->hash2[i].lock);
2832         }
2833 }
2834 
2835 u32 udp_flow_hashrnd(void)
2836 {
2837         static u32 hashrnd __read_mostly;
2838 
2839         net_get_random_once(&hashrnd, sizeof(hashrnd));
2840 
2841         return hashrnd;
2842 }
2843 EXPORT_SYMBOL(udp_flow_hashrnd);
2844 
2845 void __init udp_init(void)
2846 {
2847         unsigned long limit;
2848         unsigned int i;
2849 
2850         udp_table_init(&udp_table, "UDP");
2851         limit = nr_free_buffer_pages() / 8;
2852         limit = max(limit, 128UL);
2853         sysctl_udp_mem[0] = limit / 4 * 3;
2854         sysctl_udp_mem[1] = limit;
2855         sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2;
2856 
2857         sysctl_udp_rmem_min = SK_MEM_QUANTUM;
2858         sysctl_udp_wmem_min = SK_MEM_QUANTUM;
2859 
2860         /* 16 spinlocks per cpu */
2861         udp_busylocks_log = ilog2(nr_cpu_ids) + 4;
2862         udp_busylocks = kmalloc(sizeof(spinlock_t) << udp_busylocks_log,
2863                                 GFP_KERNEL);
2864         if (!udp_busylocks)
2865                 panic("UDP: failed to alloc udp_busylocks\n");
2866         for (i = 0; i < (1U << udp_busylocks_log); i++)
2867                 spin_lock_init(udp_busylocks + i);
2868 }
2869 

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