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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/memblock.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 atomic_long_t udp_memory_allocated;
126 EXPORT_SYMBOL(udp_memory_allocated);
127 
128 #define MAX_UDP_PORTS 65536
129 #define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN)
130 
131 /* IPCB reference means this can not be used from early demux */
132 static bool udp_lib_exact_dif_match(struct net *net, struct sk_buff *skb)
133 {
134 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
135         if (!net->ipv4.sysctl_udp_l3mdev_accept &&
136             skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
137                 return true;
138 #endif
139         return false;
140 }
141 
142 static int udp_lib_lport_inuse(struct net *net, __u16 num,
143                                const struct udp_hslot *hslot,
144                                unsigned long *bitmap,
145                                struct sock *sk, unsigned int log)
146 {
147         struct sock *sk2;
148         kuid_t uid = sock_i_uid(sk);
149 
150         sk_for_each(sk2, &hslot->head) {
151                 if (net_eq(sock_net(sk2), net) &&
152                     sk2 != sk &&
153                     (bitmap || udp_sk(sk2)->udp_port_hash == num) &&
154                     (!sk2->sk_reuse || !sk->sk_reuse) &&
155                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
156                      sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
157                     inet_rcv_saddr_equal(sk, sk2, true)) {
158                         if (sk2->sk_reuseport && sk->sk_reuseport &&
159                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
160                             uid_eq(uid, sock_i_uid(sk2))) {
161                                 if (!bitmap)
162                                         return 0;
163                         } else {
164                                 if (!bitmap)
165                                         return 1;
166                                 __set_bit(udp_sk(sk2)->udp_port_hash >> log,
167                                           bitmap);
168                         }
169                 }
170         }
171         return 0;
172 }
173 
174 /*
175  * Note: we still hold spinlock of primary hash chain, so no other writer
176  * can insert/delete a socket with local_port == num
177  */
178 static int udp_lib_lport_inuse2(struct net *net, __u16 num,
179                                 struct udp_hslot *hslot2,
180                                 struct sock *sk)
181 {
182         struct sock *sk2;
183         kuid_t uid = sock_i_uid(sk);
184         int res = 0;
185 
186         spin_lock(&hslot2->lock);
187         udp_portaddr_for_each_entry(sk2, &hslot2->head) {
188                 if (net_eq(sock_net(sk2), net) &&
189                     sk2 != sk &&
190                     (udp_sk(sk2)->udp_port_hash == num) &&
191                     (!sk2->sk_reuse || !sk->sk_reuse) &&
192                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
193                      sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
194                     inet_rcv_saddr_equal(sk, sk2, true)) {
195                         if (sk2->sk_reuseport && sk->sk_reuseport &&
196                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
197                             uid_eq(uid, sock_i_uid(sk2))) {
198                                 res = 0;
199                         } else {
200                                 res = 1;
201                         }
202                         break;
203                 }
204         }
205         spin_unlock(&hslot2->lock);
206         return res;
207 }
208 
209 static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot)
210 {
211         struct net *net = sock_net(sk);
212         kuid_t uid = sock_i_uid(sk);
213         struct sock *sk2;
214 
215         sk_for_each(sk2, &hslot->head) {
216                 if (net_eq(sock_net(sk2), net) &&
217                     sk2 != sk &&
218                     sk2->sk_family == sk->sk_family &&
219                     ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
220                     (udp_sk(sk2)->udp_port_hash == udp_sk(sk)->udp_port_hash) &&
221                     (sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
222                     sk2->sk_reuseport && uid_eq(uid, sock_i_uid(sk2)) &&
223                     inet_rcv_saddr_equal(sk, sk2, false)) {
224                         return reuseport_add_sock(sk, sk2,
225                                                   inet_rcv_saddr_any(sk));
226                 }
227         }
228 
229         return reuseport_alloc(sk, inet_rcv_saddr_any(sk));
230 }
231 
232 /**
233  *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
234  *
235  *  @sk:          socket struct in question
236  *  @snum:        port number to look up
237  *  @hash2_nulladdr: AF-dependent hash value in secondary hash chains,
238  *                   with NULL address
239  */
240 int udp_lib_get_port(struct sock *sk, unsigned short snum,
241                      unsigned int hash2_nulladdr)
242 {
243         struct udp_hslot *hslot, *hslot2;
244         struct udp_table *udptable = sk->sk_prot->h.udp_table;
245         int    error = 1;
246         struct net *net = sock_net(sk);
247 
248         if (!snum) {
249                 int low, high, remaining;
250                 unsigned int rand;
251                 unsigned short first, last;
252                 DECLARE_BITMAP(bitmap, PORTS_PER_CHAIN);
253 
254                 inet_get_local_port_range(net, &low, &high);
255                 remaining = (high - low) + 1;
256 
257                 rand = prandom_u32();
258                 first = reciprocal_scale(rand, remaining) + low;
259                 /*
260                  * force rand to be an odd multiple of UDP_HTABLE_SIZE
261                  */
262                 rand = (rand | 1) * (udptable->mask + 1);
263                 last = first + udptable->mask + 1;
264                 do {
265                         hslot = udp_hashslot(udptable, net, first);
266                         bitmap_zero(bitmap, PORTS_PER_CHAIN);
267                         spin_lock_bh(&hslot->lock);
268                         udp_lib_lport_inuse(net, snum, hslot, bitmap, sk,
269                                             udptable->log);
270 
271                         snum = first;
272                         /*
273                          * Iterate on all possible values of snum for this hash.
274                          * Using steps of an odd multiple of UDP_HTABLE_SIZE
275                          * give us randomization and full range coverage.
276                          */
277                         do {
278                                 if (low <= snum && snum <= high &&
279                                     !test_bit(snum >> udptable->log, bitmap) &&
280                                     !inet_is_local_reserved_port(net, snum))
281                                         goto found;
282                                 snum += rand;
283                         } while (snum != first);
284                         spin_unlock_bh(&hslot->lock);
285                         cond_resched();
286                 } while (++first != last);
287                 goto fail;
288         } else {
289                 hslot = udp_hashslot(udptable, net, snum);
290                 spin_lock_bh(&hslot->lock);
291                 if (hslot->count > 10) {
292                         int exist;
293                         unsigned int slot2 = udp_sk(sk)->udp_portaddr_hash ^ snum;
294 
295                         slot2          &= udptable->mask;
296                         hash2_nulladdr &= udptable->mask;
297 
298                         hslot2 = udp_hashslot2(udptable, slot2);
299                         if (hslot->count < hslot2->count)
300                                 goto scan_primary_hash;
301 
302                         exist = udp_lib_lport_inuse2(net, snum, hslot2, sk);
303                         if (!exist && (hash2_nulladdr != slot2)) {
304                                 hslot2 = udp_hashslot2(udptable, hash2_nulladdr);
305                                 exist = udp_lib_lport_inuse2(net, snum, hslot2,
306                                                              sk);
307                         }
308                         if (exist)
309                                 goto fail_unlock;
310                         else
311                                 goto found;
312                 }
313 scan_primary_hash:
314                 if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, 0))
315                         goto fail_unlock;
316         }
317 found:
318         inet_sk(sk)->inet_num = snum;
319         udp_sk(sk)->udp_port_hash = snum;
320         udp_sk(sk)->udp_portaddr_hash ^= snum;
321         if (sk_unhashed(sk)) {
322                 if (sk->sk_reuseport &&
323                     udp_reuseport_add_sock(sk, hslot)) {
324                         inet_sk(sk)->inet_num = 0;
325                         udp_sk(sk)->udp_port_hash = 0;
326                         udp_sk(sk)->udp_portaddr_hash ^= snum;
327                         goto fail_unlock;
328                 }
329 
330                 sk_add_node_rcu(sk, &hslot->head);
331                 hslot->count++;
332                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
333 
334                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
335                 spin_lock(&hslot2->lock);
336                 if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
337                     sk->sk_family == AF_INET6)
338                         hlist_add_tail_rcu(&udp_sk(sk)->udp_portaddr_node,
339                                            &hslot2->head);
340                 else
341                         hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
342                                            &hslot2->head);
343                 hslot2->count++;
344                 spin_unlock(&hslot2->lock);
345         }
346         sock_set_flag(sk, SOCK_RCU_FREE);
347         error = 0;
348 fail_unlock:
349         spin_unlock_bh(&hslot->lock);
350 fail:
351         return error;
352 }
353 EXPORT_SYMBOL(udp_lib_get_port);
354 
355 int udp_v4_get_port(struct sock *sk, unsigned short snum)
356 {
357         unsigned int hash2_nulladdr =
358                 ipv4_portaddr_hash(sock_net(sk), htonl(INADDR_ANY), snum);
359         unsigned int hash2_partial =
360                 ipv4_portaddr_hash(sock_net(sk), inet_sk(sk)->inet_rcv_saddr, 0);
361 
362         /* precompute partial secondary hash */
363         udp_sk(sk)->udp_portaddr_hash = hash2_partial;
364         return udp_lib_get_port(sk, snum, hash2_nulladdr);
365 }
366 
367 static int compute_score(struct sock *sk, struct net *net,
368                          __be32 saddr, __be16 sport,
369                          __be32 daddr, unsigned short hnum,
370                          int dif, int sdif, bool exact_dif)
371 {
372         int score;
373         struct inet_sock *inet;
374 
375         if (!net_eq(sock_net(sk), net) ||
376             udp_sk(sk)->udp_port_hash != hnum ||
377             ipv6_only_sock(sk))
378                 return -1;
379 
380         score = (sk->sk_family == PF_INET) ? 2 : 1;
381         inet = inet_sk(sk);
382 
383         if (inet->inet_rcv_saddr) {
384                 if (inet->inet_rcv_saddr != daddr)
385                         return -1;
386                 score += 4;
387         }
388 
389         if (inet->inet_daddr) {
390                 if (inet->inet_daddr != saddr)
391                         return -1;
392                 score += 4;
393         }
394 
395         if (inet->inet_dport) {
396                 if (inet->inet_dport != sport)
397                         return -1;
398                 score += 4;
399         }
400 
401         if (sk->sk_bound_dev_if || exact_dif) {
402                 bool dev_match = (sk->sk_bound_dev_if == dif ||
403                                   sk->sk_bound_dev_if == sdif);
404 
405                 if (!dev_match)
406                         return -1;
407                 if (sk->sk_bound_dev_if)
408                         score += 4;
409         }
410 
411         if (sk->sk_incoming_cpu == raw_smp_processor_id())
412                 score++;
413         return score;
414 }
415 
416 static u32 udp_ehashfn(const struct net *net, const __be32 laddr,
417                        const __u16 lport, const __be32 faddr,
418                        const __be16 fport)
419 {
420         static u32 udp_ehash_secret __read_mostly;
421 
422         net_get_random_once(&udp_ehash_secret, sizeof(udp_ehash_secret));
423 
424         return __inet_ehashfn(laddr, lport, faddr, fport,
425                               udp_ehash_secret + net_hash_mix(net));
426 }
427 
428 /* called with rcu_read_lock() */
429 static struct sock *udp4_lib_lookup2(struct net *net,
430                                      __be32 saddr, __be16 sport,
431                                      __be32 daddr, unsigned int hnum,
432                                      int dif, int sdif, bool exact_dif,
433                                      struct udp_hslot *hslot2,
434                                      struct sk_buff *skb)
435 {
436         struct sock *sk, *result;
437         int score, badness;
438         u32 hash = 0;
439 
440         result = NULL;
441         badness = 0;
442         udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
443                 score = compute_score(sk, net, saddr, sport,
444                                       daddr, hnum, dif, sdif, exact_dif);
445                 if (score > badness) {
446                         if (sk->sk_reuseport) {
447                                 hash = udp_ehashfn(net, daddr, hnum,
448                                                    saddr, sport);
449                                 result = reuseport_select_sock(sk, hash, skb,
450                                                         sizeof(struct udphdr));
451                                 if (result)
452                                         return result;
453                         }
454                         badness = score;
455                         result = sk;
456                 }
457         }
458         return result;
459 }
460 
461 /* UDP is nearly always wildcards out the wazoo, it makes no sense to try
462  * harder than this. -DaveM
463  */
464 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
465                 __be16 sport, __be32 daddr, __be16 dport, int dif,
466                 int sdif, struct udp_table *udptable, struct sk_buff *skb)
467 {
468         struct sock *sk, *result;
469         unsigned short hnum = ntohs(dport);
470         unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
471         struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
472         bool exact_dif = udp_lib_exact_dif_match(net, skb);
473         int score, badness;
474         u32 hash = 0;
475 
476         if (hslot->count > 10) {
477                 hash2 = ipv4_portaddr_hash(net, daddr, hnum);
478                 slot2 = hash2 & udptable->mask;
479                 hslot2 = &udptable->hash2[slot2];
480                 if (hslot->count < hslot2->count)
481                         goto begin;
482 
483                 result = udp4_lib_lookup2(net, saddr, sport,
484                                           daddr, hnum, dif, sdif,
485                                           exact_dif, hslot2, skb);
486                 if (!result) {
487                         unsigned int old_slot2 = slot2;
488                         hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
489                         slot2 = hash2 & udptable->mask;
490                         /* avoid searching the same slot again. */
491                         if (unlikely(slot2 == old_slot2))
492                                 return result;
493 
494                         hslot2 = &udptable->hash2[slot2];
495                         if (hslot->count < hslot2->count)
496                                 goto begin;
497 
498                         result = udp4_lib_lookup2(net, saddr, sport,
499                                                   daddr, hnum, dif, sdif,
500                                                   exact_dif, hslot2, skb);
501                 }
502                 if (unlikely(IS_ERR(result)))
503                         return NULL;
504                 return result;
505         }
506 begin:
507         result = NULL;
508         badness = 0;
509         sk_for_each_rcu(sk, &hslot->head) {
510                 score = compute_score(sk, net, saddr, sport,
511                                       daddr, hnum, dif, sdif, exact_dif);
512                 if (score > badness) {
513                         if (sk->sk_reuseport) {
514                                 hash = udp_ehashfn(net, daddr, hnum,
515                                                    saddr, sport);
516                                 result = reuseport_select_sock(sk, hash, skb,
517                                                         sizeof(struct udphdr));
518                                 if (unlikely(IS_ERR(result)))
519                                         return NULL;
520                                 if (result)
521                                         return result;
522                         }
523                         result = sk;
524                         badness = score;
525                 }
526         }
527         return result;
528 }
529 EXPORT_SYMBOL_GPL(__udp4_lib_lookup);
530 
531 static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
532                                                  __be16 sport, __be16 dport,
533                                                  struct udp_table *udptable)
534 {
535         const struct iphdr *iph = ip_hdr(skb);
536 
537         return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
538                                  iph->daddr, dport, inet_iif(skb),
539                                  inet_sdif(skb), udptable, skb);
540 }
541 
542 struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
543                                  __be16 sport, __be16 dport)
544 {
545         return __udp4_lib_lookup_skb(skb, sport, dport, &udp_table);
546 }
547 EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
548 
549 /* Must be called under rcu_read_lock().
550  * Does increment socket refcount.
551  */
552 #if IS_ENABLED(CONFIG_NF_TPROXY_IPV4) || IS_ENABLED(CONFIG_NF_SOCKET_IPV4)
553 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
554                              __be32 daddr, __be16 dport, int dif)
555 {
556         struct sock *sk;
557 
558         sk = __udp4_lib_lookup(net, saddr, sport, daddr, dport,
559                                dif, 0, &udp_table, NULL);
560         if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
561                 sk = NULL;
562         return sk;
563 }
564 EXPORT_SYMBOL_GPL(udp4_lib_lookup);
565 #endif
566 
567 static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk,
568                                        __be16 loc_port, __be32 loc_addr,
569                                        __be16 rmt_port, __be32 rmt_addr,
570                                        int dif, int sdif, unsigned short hnum)
571 {
572         struct inet_sock *inet = inet_sk(sk);
573 
574         if (!net_eq(sock_net(sk), net) ||
575             udp_sk(sk)->udp_port_hash != hnum ||
576             (inet->inet_daddr && inet->inet_daddr != rmt_addr) ||
577             (inet->inet_dport != rmt_port && inet->inet_dport) ||
578             (inet->inet_rcv_saddr && inet->inet_rcv_saddr != loc_addr) ||
579             ipv6_only_sock(sk) ||
580             (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif &&
581              sk->sk_bound_dev_if != sdif))
582                 return false;
583         if (!ip_mc_sf_allow(sk, loc_addr, rmt_addr, dif, sdif))
584                 return false;
585         return true;
586 }
587 
588 /*
589  * This routine is called by the ICMP module when it gets some
590  * sort of error condition.  If err < 0 then the socket should
591  * be closed and the error returned to the user.  If err > 0
592  * it's just the icmp type << 8 | icmp code.
593  * Header points to the ip header of the error packet. We move
594  * on past this. Then (as it used to claim before adjustment)
595  * header points to the first 8 bytes of the udp header.  We need
596  * to find the appropriate port.
597  */
598 
599 void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
600 {
601         struct inet_sock *inet;
602         const struct iphdr *iph = (const struct iphdr *)skb->data;
603         struct udphdr *uh = (struct udphdr *)(skb->data+(iph->ihl<<2));
604         const int type = icmp_hdr(skb)->type;
605         const int code = icmp_hdr(skb)->code;
606         struct sock *sk;
607         int harderr;
608         int err;
609         struct net *net = dev_net(skb->dev);
610 
611         sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
612                                iph->saddr, uh->source, skb->dev->ifindex,
613                                inet_sdif(skb), udptable, NULL);
614         if (!sk) {
615                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
616                 return; /* No socket for error */
617         }
618 
619         err = 0;
620         harderr = 0;
621         inet = inet_sk(sk);
622 
623         switch (type) {
624         default:
625         case ICMP_TIME_EXCEEDED:
626                 err = EHOSTUNREACH;
627                 break;
628         case ICMP_SOURCE_QUENCH:
629                 goto out;
630         case ICMP_PARAMETERPROB:
631                 err = EPROTO;
632                 harderr = 1;
633                 break;
634         case ICMP_DEST_UNREACH:
635                 if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
636                         ipv4_sk_update_pmtu(skb, sk, info);
637                         if (inet->pmtudisc != IP_PMTUDISC_DONT) {
638                                 err = EMSGSIZE;
639                                 harderr = 1;
640                                 break;
641                         }
642                         goto out;
643                 }
644                 err = EHOSTUNREACH;
645                 if (code <= NR_ICMP_UNREACH) {
646                         harderr = icmp_err_convert[code].fatal;
647                         err = icmp_err_convert[code].errno;
648                 }
649                 break;
650         case ICMP_REDIRECT:
651                 ipv4_sk_redirect(skb, sk);
652                 goto out;
653         }
654 
655         /*
656          *      RFC1122: OK.  Passes ICMP errors back to application, as per
657          *      4.1.3.3.
658          */
659         if (!inet->recverr) {
660                 if (!harderr || sk->sk_state != TCP_ESTABLISHED)
661                         goto out;
662         } else
663                 ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1));
664 
665         sk->sk_err = err;
666         sk->sk_error_report(sk);
667 out:
668         return;
669 }
670 
671 void udp_err(struct sk_buff *skb, u32 info)
672 {
673         __udp4_lib_err(skb, info, &udp_table);
674 }
675 
676 /*
677  * Throw away all pending data and cancel the corking. Socket is locked.
678  */
679 void udp_flush_pending_frames(struct sock *sk)
680 {
681         struct udp_sock *up = udp_sk(sk);
682 
683         if (up->pending) {
684                 up->len = 0;
685                 up->pending = 0;
686                 ip_flush_pending_frames(sk);
687         }
688 }
689 EXPORT_SYMBOL(udp_flush_pending_frames);
690 
691 /**
692  *      udp4_hwcsum  -  handle outgoing HW checksumming
693  *      @skb:   sk_buff containing the filled-in UDP header
694  *              (checksum field must be zeroed out)
695  *      @src:   source IP address
696  *      @dst:   destination IP address
697  */
698 void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst)
699 {
700         struct udphdr *uh = udp_hdr(skb);
701         int offset = skb_transport_offset(skb);
702         int len = skb->len - offset;
703         int hlen = len;
704         __wsum csum = 0;
705 
706         if (!skb_has_frag_list(skb)) {
707                 /*
708                  * Only one fragment on the socket.
709                  */
710                 skb->csum_start = skb_transport_header(skb) - skb->head;
711                 skb->csum_offset = offsetof(struct udphdr, check);
712                 uh->check = ~csum_tcpudp_magic(src, dst, len,
713                                                IPPROTO_UDP, 0);
714         } else {
715                 struct sk_buff *frags;
716 
717                 /*
718                  * HW-checksum won't work as there are two or more
719                  * fragments on the socket so that all csums of sk_buffs
720                  * should be together
721                  */
722                 skb_walk_frags(skb, frags) {
723                         csum = csum_add(csum, frags->csum);
724                         hlen -= frags->len;
725                 }
726 
727                 csum = skb_checksum(skb, offset, hlen, csum);
728                 skb->ip_summed = CHECKSUM_NONE;
729 
730                 uh->check = csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum);
731                 if (uh->check == 0)
732                         uh->check = CSUM_MANGLED_0;
733         }
734 }
735 EXPORT_SYMBOL_GPL(udp4_hwcsum);
736 
737 /* Function to set UDP checksum for an IPv4 UDP packet. This is intended
738  * for the simple case like when setting the checksum for a UDP tunnel.
739  */
740 void udp_set_csum(bool nocheck, struct sk_buff *skb,
741                   __be32 saddr, __be32 daddr, int len)
742 {
743         struct udphdr *uh = udp_hdr(skb);
744 
745         if (nocheck) {
746                 uh->check = 0;
747         } else if (skb_is_gso(skb)) {
748                 uh->check = ~udp_v4_check(len, saddr, daddr, 0);
749         } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
750                 uh->check = 0;
751                 uh->check = udp_v4_check(len, saddr, daddr, lco_csum(skb));
752                 if (uh->check == 0)
753                         uh->check = CSUM_MANGLED_0;
754         } else {
755                 skb->ip_summed = CHECKSUM_PARTIAL;
756                 skb->csum_start = skb_transport_header(skb) - skb->head;
757                 skb->csum_offset = offsetof(struct udphdr, check);
758                 uh->check = ~udp_v4_check(len, saddr, daddr, 0);
759         }
760 }
761 EXPORT_SYMBOL(udp_set_csum);
762 
763 static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
764                         struct inet_cork *cork)
765 {
766         struct sock *sk = skb->sk;
767         struct inet_sock *inet = inet_sk(sk);
768         struct udphdr *uh;
769         int err = 0;
770         int is_udplite = IS_UDPLITE(sk);
771         int offset = skb_transport_offset(skb);
772         int len = skb->len - offset;
773         __wsum csum = 0;
774 
775         /*
776          * Create a UDP header
777          */
778         uh = udp_hdr(skb);
779         uh->source = inet->inet_sport;
780         uh->dest = fl4->fl4_dport;
781         uh->len = htons(len);
782         uh->check = 0;
783 
784         if (cork->gso_size) {
785                 const int hlen = skb_network_header_len(skb) +
786                                  sizeof(struct udphdr);
787 
788                 if (hlen + cork->gso_size > cork->fragsize) {
789                         kfree_skb(skb);
790                         return -EINVAL;
791                 }
792                 if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
793                         kfree_skb(skb);
794                         return -EINVAL;
795                 }
796                 if (sk->sk_no_check_tx) {
797                         kfree_skb(skb);
798                         return -EINVAL;
799                 }
800                 if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
801                     dst_xfrm(skb_dst(skb))) {
802                         kfree_skb(skb);
803                         return -EIO;
804                 }
805 
806                 skb_shinfo(skb)->gso_size = cork->gso_size;
807                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP_L4;
808                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(len - sizeof(uh),
809                                                          cork->gso_size);
810                 goto csum_partial;
811         }
812 
813         if (is_udplite)                                  /*     UDP-Lite      */
814                 csum = udplite_csum(skb);
815 
816         else if (sk->sk_no_check_tx) {                   /* UDP csum off */
817 
818                 skb->ip_summed = CHECKSUM_NONE;
819                 goto send;
820 
821         } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
822 csum_partial:
823 
824                 udp4_hwcsum(skb, fl4->saddr, fl4->daddr);
825                 goto send;
826 
827         } else
828                 csum = udp_csum(skb);
829 
830         /* add protocol-dependent pseudo-header */
831         uh->check = csum_tcpudp_magic(fl4->saddr, fl4->daddr, len,
832                                       sk->sk_protocol, csum);
833         if (uh->check == 0)
834                 uh->check = CSUM_MANGLED_0;
835 
836 send:
837         err = ip_send_skb(sock_net(sk), skb);
838         if (err) {
839                 if (err == -ENOBUFS && !inet->recverr) {
840                         UDP_INC_STATS(sock_net(sk),
841                                       UDP_MIB_SNDBUFERRORS, is_udplite);
842                         err = 0;
843                 }
844         } else
845                 UDP_INC_STATS(sock_net(sk),
846                               UDP_MIB_OUTDATAGRAMS, is_udplite);
847         return err;
848 }
849 
850 /*
851  * Push out all pending data as one UDP datagram. Socket is locked.
852  */
853 int udp_push_pending_frames(struct sock *sk)
854 {
855         struct udp_sock  *up = udp_sk(sk);
856         struct inet_sock *inet = inet_sk(sk);
857         struct flowi4 *fl4 = &inet->cork.fl.u.ip4;
858         struct sk_buff *skb;
859         int err = 0;
860 
861         skb = ip_finish_skb(sk, fl4);
862         if (!skb)
863                 goto out;
864 
865         err = udp_send_skb(skb, fl4, &inet->cork.base);
866 
867 out:
868         up->len = 0;
869         up->pending = 0;
870         return err;
871 }
872 EXPORT_SYMBOL(udp_push_pending_frames);
873 
874 static int __udp_cmsg_send(struct cmsghdr *cmsg, u16 *gso_size)
875 {
876         switch (cmsg->cmsg_type) {
877         case UDP_SEGMENT:
878                 if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u16)))
879                         return -EINVAL;
880                 *gso_size = *(__u16 *)CMSG_DATA(cmsg);
881                 return 0;
882         default:
883                 return -EINVAL;
884         }
885 }
886 
887 int udp_cmsg_send(struct sock *sk, struct msghdr *msg, u16 *gso_size)
888 {
889         struct cmsghdr *cmsg;
890         bool need_ip = false;
891         int err;
892 
893         for_each_cmsghdr(cmsg, msg) {
894                 if (!CMSG_OK(msg, cmsg))
895                         return -EINVAL;
896 
897                 if (cmsg->cmsg_level != SOL_UDP) {
898                         need_ip = true;
899                         continue;
900                 }
901 
902                 err = __udp_cmsg_send(cmsg, gso_size);
903                 if (err)
904                         return err;
905         }
906 
907         return need_ip;
908 }
909 EXPORT_SYMBOL_GPL(udp_cmsg_send);
910 
911 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
912 {
913         struct inet_sock *inet = inet_sk(sk);
914         struct udp_sock *up = udp_sk(sk);
915         DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
916         struct flowi4 fl4_stack;
917         struct flowi4 *fl4;
918         int ulen = len;
919         struct ipcm_cookie ipc;
920         struct rtable *rt = NULL;
921         int free = 0;
922         int connected = 0;
923         __be32 daddr, faddr, saddr;
924         __be16 dport;
925         u8  tos;
926         int err, is_udplite = IS_UDPLITE(sk);
927         int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
928         int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
929         struct sk_buff *skb;
930         struct ip_options_data opt_copy;
931 
932         if (len > 0xFFFF)
933                 return -EMSGSIZE;
934 
935         /*
936          *      Check the flags.
937          */
938 
939         if (msg->msg_flags & MSG_OOB) /* Mirror BSD error message compatibility */
940                 return -EOPNOTSUPP;
941 
942         getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag;
943 
944         fl4 = &inet->cork.fl.u.ip4;
945         if (up->pending) {
946                 /*
947                  * There are pending frames.
948                  * The socket lock must be held while it's corked.
949                  */
950                 lock_sock(sk);
951                 if (likely(up->pending)) {
952                         if (unlikely(up->pending != AF_INET)) {
953                                 release_sock(sk);
954                                 return -EINVAL;
955                         }
956                         goto do_append_data;
957                 }
958                 release_sock(sk);
959         }
960         ulen += sizeof(struct udphdr);
961 
962         /*
963          *      Get and verify the address.
964          */
965         if (usin) {
966                 if (msg->msg_namelen < sizeof(*usin))
967                         return -EINVAL;
968                 if (usin->sin_family != AF_INET) {
969                         if (usin->sin_family != AF_UNSPEC)
970                                 return -EAFNOSUPPORT;
971                 }
972 
973                 daddr = usin->sin_addr.s_addr;
974                 dport = usin->sin_port;
975                 if (dport == 0)
976                         return -EINVAL;
977         } else {
978                 if (sk->sk_state != TCP_ESTABLISHED)
979                         return -EDESTADDRREQ;
980                 daddr = inet->inet_daddr;
981                 dport = inet->inet_dport;
982                 /* Open fast path for connected socket.
983                    Route will not be used, if at least one option is set.
984                  */
985                 connected = 1;
986         }
987 
988         ipcm_init_sk(&ipc, inet);
989         ipc.gso_size = up->gso_size;
990 
991         if (msg->msg_controllen) {
992                 err = udp_cmsg_send(sk, msg, &ipc.gso_size);
993                 if (err > 0)
994                         err = ip_cmsg_send(sk, msg, &ipc,
995                                            sk->sk_family == AF_INET6);
996                 if (unlikely(err < 0)) {
997                         kfree(ipc.opt);
998                         return err;
999                 }
1000                 if (ipc.opt)
1001                         free = 1;
1002                 connected = 0;
1003         }
1004         if (!ipc.opt) {
1005                 struct ip_options_rcu *inet_opt;
1006 
1007                 rcu_read_lock();
1008                 inet_opt = rcu_dereference(inet->inet_opt);
1009                 if (inet_opt) {
1010                         memcpy(&opt_copy, inet_opt,
1011                                sizeof(*inet_opt) + inet_opt->opt.optlen);
1012                         ipc.opt = &opt_copy.opt;
1013                 }
1014                 rcu_read_unlock();
1015         }
1016 
1017         if (cgroup_bpf_enabled && !connected) {
1018                 err = BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk,
1019                                             (struct sockaddr *)usin, &ipc.addr);
1020                 if (err)
1021                         goto out_free;
1022                 if (usin) {
1023                         if (usin->sin_port == 0) {
1024                                 /* BPF program set invalid port. Reject it. */
1025                                 err = -EINVAL;
1026                                 goto out_free;
1027                         }
1028                         daddr = usin->sin_addr.s_addr;
1029                         dport = usin->sin_port;
1030                 }
1031         }
1032 
1033         saddr = ipc.addr;
1034         ipc.addr = faddr = daddr;
1035 
1036         if (ipc.opt && ipc.opt->opt.srr) {
1037                 if (!daddr) {
1038                         err = -EINVAL;
1039                         goto out_free;
1040                 }
1041                 faddr = ipc.opt->opt.faddr;
1042                 connected = 0;
1043         }
1044         tos = get_rttos(&ipc, inet);
1045         if (sock_flag(sk, SOCK_LOCALROUTE) ||
1046             (msg->msg_flags & MSG_DONTROUTE) ||
1047             (ipc.opt && ipc.opt->opt.is_strictroute)) {
1048                 tos |= RTO_ONLINK;
1049                 connected = 0;
1050         }
1051 
1052         if (ipv4_is_multicast(daddr)) {
1053                 if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
1054                         ipc.oif = inet->mc_index;
1055                 if (!saddr)
1056                         saddr = inet->mc_addr;
1057                 connected = 0;
1058         } else if (!ipc.oif) {
1059                 ipc.oif = inet->uc_index;
1060         } else if (ipv4_is_lbcast(daddr) && inet->uc_index) {
1061                 /* oif is set, packet is to local broadcast and
1062                  * and uc_index is set. oif is most likely set
1063                  * by sk_bound_dev_if. If uc_index != oif check if the
1064                  * oif is an L3 master and uc_index is an L3 slave.
1065                  * If so, we want to allow the send using the uc_index.
1066                  */
1067                 if (ipc.oif != inet->uc_index &&
1068                     ipc.oif == l3mdev_master_ifindex_by_index(sock_net(sk),
1069                                                               inet->uc_index)) {
1070                         ipc.oif = inet->uc_index;
1071                 }
1072         }
1073 
1074         if (connected)
1075                 rt = (struct rtable *)sk_dst_check(sk, 0);
1076 
1077         if (!rt) {
1078                 struct net *net = sock_net(sk);
1079                 __u8 flow_flags = inet_sk_flowi_flags(sk);
1080 
1081                 fl4 = &fl4_stack;
1082 
1083                 flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
1084                                    RT_SCOPE_UNIVERSE, sk->sk_protocol,
1085                                    flow_flags,
1086                                    faddr, saddr, dport, inet->inet_sport,
1087                                    sk->sk_uid);
1088 
1089                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
1090                 rt = ip_route_output_flow(net, fl4, sk);
1091                 if (IS_ERR(rt)) {
1092                         err = PTR_ERR(rt);
1093                         rt = NULL;
1094                         if (err == -ENETUNREACH)
1095                                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
1096                         goto out;
1097                 }
1098 
1099                 err = -EACCES;
1100                 if ((rt->rt_flags & RTCF_BROADCAST) &&
1101                     !sock_flag(sk, SOCK_BROADCAST))
1102                         goto out;
1103                 if (connected)
1104                         sk_dst_set(sk, dst_clone(&rt->dst));
1105         }
1106 
1107         if (msg->msg_flags&MSG_CONFIRM)
1108                 goto do_confirm;
1109 back_from_confirm:
1110 
1111         saddr = fl4->saddr;
1112         if (!ipc.addr)
1113                 daddr = ipc.addr = fl4->daddr;
1114 
1115         /* Lockless fast path for the non-corking case. */
1116         if (!corkreq) {
1117                 struct inet_cork cork;
1118 
1119                 skb = ip_make_skb(sk, fl4, getfrag, msg, ulen,
1120                                   sizeof(struct udphdr), &ipc, &rt,
1121                                   &cork, msg->msg_flags);
1122                 err = PTR_ERR(skb);
1123                 if (!IS_ERR_OR_NULL(skb))
1124                         err = udp_send_skb(skb, fl4, &cork);
1125                 goto out;
1126         }
1127 
1128         lock_sock(sk);
1129         if (unlikely(up->pending)) {
1130                 /* The socket is already corked while preparing it. */
1131                 /* ... which is an evident application bug. --ANK */
1132                 release_sock(sk);
1133 
1134                 net_dbg_ratelimited("socket already corked\n");
1135                 err = -EINVAL;
1136                 goto out;
1137         }
1138         /*
1139          *      Now cork the socket to pend data.
1140          */
1141         fl4 = &inet->cork.fl.u.ip4;
1142         fl4->daddr = daddr;
1143         fl4->saddr = saddr;
1144         fl4->fl4_dport = dport;
1145         fl4->fl4_sport = inet->inet_sport;
1146         up->pending = AF_INET;
1147 
1148 do_append_data:
1149         up->len += ulen;
1150         err = ip_append_data(sk, fl4, getfrag, msg, ulen,
1151                              sizeof(struct udphdr), &ipc, &rt,
1152                              corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
1153         if (err)
1154                 udp_flush_pending_frames(sk);
1155         else if (!corkreq)
1156                 err = udp_push_pending_frames(sk);
1157         else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
1158                 up->pending = 0;
1159         release_sock(sk);
1160 
1161 out:
1162         ip_rt_put(rt);
1163 out_free:
1164         if (free)
1165                 kfree(ipc.opt);
1166         if (!err)
1167                 return len;
1168         /*
1169          * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
1170          * ENOBUFS might not be good (it's not tunable per se), but otherwise
1171          * we don't have a good statistic (IpOutDiscards but it can be too many
1172          * things).  We could add another new stat but at least for now that
1173          * seems like overkill.
1174          */
1175         if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
1176                 UDP_INC_STATS(sock_net(sk),
1177                               UDP_MIB_SNDBUFERRORS, is_udplite);
1178         }
1179         return err;
1180 
1181 do_confirm:
1182         if (msg->msg_flags & MSG_PROBE)
1183                 dst_confirm_neigh(&rt->dst, &fl4->daddr);
1184         if (!(msg->msg_flags&MSG_PROBE) || len)
1185                 goto back_from_confirm;
1186         err = 0;
1187         goto out;
1188 }
1189 EXPORT_SYMBOL(udp_sendmsg);
1190 
1191 int udp_sendpage(struct sock *sk, struct page *page, int offset,
1192                  size_t size, int flags)
1193 {
1194         struct inet_sock *inet = inet_sk(sk);
1195         struct udp_sock *up = udp_sk(sk);
1196         int ret;
1197 
1198         if (flags & MSG_SENDPAGE_NOTLAST)
1199                 flags |= MSG_MORE;
1200 
1201         if (!up->pending) {
1202                 struct msghdr msg = {   .msg_flags = flags|MSG_MORE };
1203 
1204                 /* Call udp_sendmsg to specify destination address which
1205                  * sendpage interface can't pass.
1206                  * This will succeed only when the socket is connected.
1207                  */
1208                 ret = udp_sendmsg(sk, &msg, 0);
1209                 if (ret < 0)
1210                         return ret;
1211         }
1212 
1213         lock_sock(sk);
1214 
1215         if (unlikely(!up->pending)) {
1216                 release_sock(sk);
1217 
1218                 net_dbg_ratelimited("cork failed\n");
1219                 return -EINVAL;
1220         }
1221 
1222         ret = ip_append_page(sk, &inet->cork.fl.u.ip4,
1223                              page, offset, size, flags);
1224         if (ret == -EOPNOTSUPP) {
1225                 release_sock(sk);
1226                 return sock_no_sendpage(sk->sk_socket, page, offset,
1227                                         size, flags);
1228         }
1229         if (ret < 0) {
1230                 udp_flush_pending_frames(sk);
1231                 goto out;
1232         }
1233 
1234         up->len += size;
1235         if (!(up->corkflag || (flags&MSG_MORE)))
1236                 ret = udp_push_pending_frames(sk);
1237         if (!ret)
1238                 ret = size;
1239 out:
1240         release_sock(sk);
1241         return ret;
1242 }
1243 
1244 #define UDP_SKB_IS_STATELESS 0x80000000
1245 
1246 static void udp_set_dev_scratch(struct sk_buff *skb)
1247 {
1248         struct udp_dev_scratch *scratch = udp_skb_scratch(skb);
1249 
1250         BUILD_BUG_ON(sizeof(struct udp_dev_scratch) > sizeof(long));
1251         scratch->_tsize_state = skb->truesize;
1252 #if BITS_PER_LONG == 64
1253         scratch->len = skb->len;
1254         scratch->csum_unnecessary = !!skb_csum_unnecessary(skb);
1255         scratch->is_linear = !skb_is_nonlinear(skb);
1256 #endif
1257         /* all head states execept sp (dst, sk, nf) are always cleared by
1258          * udp_rcv() and we need to preserve secpath, if present, to eventually
1259          * process IP_CMSG_PASSSEC at recvmsg() time
1260          */
1261         if (likely(!skb_sec_path(skb)))
1262                 scratch->_tsize_state |= UDP_SKB_IS_STATELESS;
1263 }
1264 
1265 static int udp_skb_truesize(struct sk_buff *skb)
1266 {
1267         return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS;
1268 }
1269 
1270 static bool udp_skb_has_head_state(struct sk_buff *skb)
1271 {
1272         return !(udp_skb_scratch(skb)->_tsize_state & UDP_SKB_IS_STATELESS);
1273 }
1274 
1275 /* fully reclaim rmem/fwd memory allocated for skb */
1276 static void udp_rmem_release(struct sock *sk, int size, int partial,
1277                              bool rx_queue_lock_held)
1278 {
1279         struct udp_sock *up = udp_sk(sk);
1280         struct sk_buff_head *sk_queue;
1281         int amt;
1282 
1283         if (likely(partial)) {
1284                 up->forward_deficit += size;
1285                 size = up->forward_deficit;
1286                 if (size < (sk->sk_rcvbuf >> 2))
1287                         return;
1288         } else {
1289                 size += up->forward_deficit;
1290         }
1291         up->forward_deficit = 0;
1292 
1293         /* acquire the sk_receive_queue for fwd allocated memory scheduling,
1294          * if the called don't held it already
1295          */
1296         sk_queue = &sk->sk_receive_queue;
1297         if (!rx_queue_lock_held)
1298                 spin_lock(&sk_queue->lock);
1299 
1300 
1301         sk->sk_forward_alloc += size;
1302         amt = (sk->sk_forward_alloc - partial) & ~(SK_MEM_QUANTUM - 1);
1303         sk->sk_forward_alloc -= amt;
1304 
1305         if (amt)
1306                 __sk_mem_reduce_allocated(sk, amt >> SK_MEM_QUANTUM_SHIFT);
1307 
1308         atomic_sub(size, &sk->sk_rmem_alloc);
1309 
1310         /* this can save us from acquiring the rx queue lock on next receive */
1311         skb_queue_splice_tail_init(sk_queue, &up->reader_queue);
1312 
1313         if (!rx_queue_lock_held)
1314                 spin_unlock(&sk_queue->lock);
1315 }
1316 
1317 /* Note: called with reader_queue.lock held.
1318  * Instead of using skb->truesize here, find a copy of it in skb->dev_scratch
1319  * This avoids a cache line miss while receive_queue lock is held.
1320  * Look at __udp_enqueue_schedule_skb() to find where this copy is done.
1321  */
1322 void udp_skb_destructor(struct sock *sk, struct sk_buff *skb)
1323 {
1324         prefetch(&skb->data);
1325         udp_rmem_release(sk, udp_skb_truesize(skb), 1, false);
1326 }
1327 EXPORT_SYMBOL(udp_skb_destructor);
1328 
1329 /* as above, but the caller held the rx queue lock, too */
1330 static void udp_skb_dtor_locked(struct sock *sk, struct sk_buff *skb)
1331 {
1332         prefetch(&skb->data);
1333         udp_rmem_release(sk, udp_skb_truesize(skb), 1, true);
1334 }
1335 
1336 /* Idea of busylocks is to let producers grab an extra spinlock
1337  * to relieve pressure on the receive_queue spinlock shared by consumer.
1338  * Under flood, this means that only one producer can be in line
1339  * trying to acquire the receive_queue spinlock.
1340  * These busylock can be allocated on a per cpu manner, instead of a
1341  * per socket one (that would consume a cache line per socket)
1342  */
1343 static int udp_busylocks_log __read_mostly;
1344 static spinlock_t *udp_busylocks __read_mostly;
1345 
1346 static spinlock_t *busylock_acquire(void *ptr)
1347 {
1348         spinlock_t *busy;
1349 
1350         busy = udp_busylocks + hash_ptr(ptr, udp_busylocks_log);
1351         spin_lock(busy);
1352         return busy;
1353 }
1354 
1355 static void busylock_release(spinlock_t *busy)
1356 {
1357         if (busy)
1358                 spin_unlock(busy);
1359 }
1360 
1361 int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
1362 {
1363         struct sk_buff_head *list = &sk->sk_receive_queue;
1364         int rmem, delta, amt, err = -ENOMEM;
1365         spinlock_t *busy = NULL;
1366         int size;
1367 
1368         /* try to avoid the costly atomic add/sub pair when the receive
1369          * queue is full; always allow at least a packet
1370          */
1371         rmem = atomic_read(&sk->sk_rmem_alloc);
1372         if (rmem > sk->sk_rcvbuf)
1373                 goto drop;
1374 
1375         /* Under mem pressure, it might be helpful to help udp_recvmsg()
1376          * having linear skbs :
1377          * - Reduce memory overhead and thus increase receive queue capacity
1378          * - Less cache line misses at copyout() time
1379          * - Less work at consume_skb() (less alien page frag freeing)
1380          */
1381         if (rmem > (sk->sk_rcvbuf >> 1)) {
1382                 skb_condense(skb);
1383 
1384                 busy = busylock_acquire(sk);
1385         }
1386         size = skb->truesize;
1387         udp_set_dev_scratch(skb);
1388 
1389         /* we drop only if the receive buf is full and the receive
1390          * queue contains some other skb
1391          */
1392         rmem = atomic_add_return(size, &sk->sk_rmem_alloc);
1393         if (rmem > (size + sk->sk_rcvbuf))
1394                 goto uncharge_drop;
1395 
1396         spin_lock(&list->lock);
1397         if (size >= sk->sk_forward_alloc) {
1398                 amt = sk_mem_pages(size);
1399                 delta = amt << SK_MEM_QUANTUM_SHIFT;
1400                 if (!__sk_mem_raise_allocated(sk, delta, amt, SK_MEM_RECV)) {
1401                         err = -ENOBUFS;
1402                         spin_unlock(&list->lock);
1403                         goto uncharge_drop;
1404                 }
1405 
1406                 sk->sk_forward_alloc += delta;
1407         }
1408 
1409         sk->sk_forward_alloc -= size;
1410 
1411         /* no need to setup a destructor, we will explicitly release the
1412          * forward allocated memory on dequeue
1413          */
1414         sock_skb_set_dropcount(sk, skb);
1415 
1416         __skb_queue_tail(list, skb);
1417         spin_unlock(&list->lock);
1418 
1419         if (!sock_flag(sk, SOCK_DEAD))
1420                 sk->sk_data_ready(sk);
1421 
1422         busylock_release(busy);
1423         return 0;
1424 
1425 uncharge_drop:
1426         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
1427 
1428 drop:
1429         atomic_inc(&sk->sk_drops);
1430         busylock_release(busy);
1431         return err;
1432 }
1433 EXPORT_SYMBOL_GPL(__udp_enqueue_schedule_skb);
1434 
1435 void udp_destruct_sock(struct sock *sk)
1436 {
1437         /* reclaim completely the forward allocated memory */
1438         struct udp_sock *up = udp_sk(sk);
1439         unsigned int total = 0;
1440         struct sk_buff *skb;
1441 
1442         skb_queue_splice_tail_init(&sk->sk_receive_queue, &up->reader_queue);
1443         while ((skb = __skb_dequeue(&up->reader_queue)) != NULL) {
1444                 total += skb->truesize;
1445                 kfree_skb(skb);
1446         }
1447         udp_rmem_release(sk, total, 0, true);
1448 
1449         inet_sock_destruct(sk);
1450 }
1451 EXPORT_SYMBOL_GPL(udp_destruct_sock);
1452 
1453 int udp_init_sock(struct sock *sk)
1454 {
1455         skb_queue_head_init(&udp_sk(sk)->reader_queue);
1456         sk->sk_destruct = udp_destruct_sock;
1457         return 0;
1458 }
1459 EXPORT_SYMBOL_GPL(udp_init_sock);
1460 
1461 void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
1462 {
1463         if (unlikely(READ_ONCE(sk->sk_peek_off) >= 0)) {
1464                 bool slow = lock_sock_fast(sk);
1465 
1466                 sk_peek_offset_bwd(sk, len);
1467                 unlock_sock_fast(sk, slow);
1468         }
1469 
1470         if (!skb_unref(skb))
1471                 return;
1472 
1473         /* In the more common cases we cleared the head states previously,
1474          * see __udp_queue_rcv_skb().
1475          */
1476         if (unlikely(udp_skb_has_head_state(skb)))
1477                 skb_release_head_state(skb);
1478         __consume_stateless_skb(skb);
1479 }
1480 EXPORT_SYMBOL_GPL(skb_consume_udp);
1481 
1482 static struct sk_buff *__first_packet_length(struct sock *sk,
1483                                              struct sk_buff_head *rcvq,
1484                                              int *total)
1485 {
1486         struct sk_buff *skb;
1487 
1488         while ((skb = skb_peek(rcvq)) != NULL) {
1489                 if (udp_lib_checksum_complete(skb)) {
1490                         __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS,
1491                                         IS_UDPLITE(sk));
1492                         __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS,
1493                                         IS_UDPLITE(sk));
1494                         atomic_inc(&sk->sk_drops);
1495                         __skb_unlink(skb, rcvq);
1496                         *total += skb->truesize;
1497                         kfree_skb(skb);
1498                 } else {
1499                         /* the csum related bits could be changed, refresh
1500                          * the scratch area
1501                          */
1502                         udp_set_dev_scratch(skb);
1503                         break;
1504                 }
1505         }
1506         return skb;
1507 }
1508 
1509 /**
1510  *      first_packet_length     - return length of first packet in receive queue
1511  *      @sk: socket
1512  *
1513  *      Drops all bad checksum frames, until a valid one is found.
1514  *      Returns the length of found skb, or -1 if none is found.
1515  */
1516 static int first_packet_length(struct sock *sk)
1517 {
1518         struct sk_buff_head *rcvq = &udp_sk(sk)->reader_queue;
1519         struct sk_buff_head *sk_queue = &sk->sk_receive_queue;
1520         struct sk_buff *skb;
1521         int total = 0;
1522         int res;
1523 
1524         spin_lock_bh(&rcvq->lock);
1525         skb = __first_packet_length(sk, rcvq, &total);
1526         if (!skb && !skb_queue_empty(sk_queue)) {
1527                 spin_lock(&sk_queue->lock);
1528                 skb_queue_splice_tail_init(sk_queue, rcvq);
1529                 spin_unlock(&sk_queue->lock);
1530 
1531                 skb = __first_packet_length(sk, rcvq, &total);
1532         }
1533         res = skb ? skb->len : -1;
1534         if (total)
1535                 udp_rmem_release(sk, total, 1, false);
1536         spin_unlock_bh(&rcvq->lock);
1537         return res;
1538 }
1539 
1540 /*
1541  *      IOCTL requests applicable to the UDP protocol
1542  */
1543 
1544 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
1545 {
1546         switch (cmd) {
1547         case SIOCOUTQ:
1548         {
1549                 int amount = sk_wmem_alloc_get(sk);
1550 
1551                 return put_user(amount, (int __user *)arg);
1552         }
1553 
1554         case SIOCINQ:
1555         {
1556                 int amount = max_t(int, 0, first_packet_length(sk));
1557 
1558                 return put_user(amount, (int __user *)arg);
1559         }
1560 
1561         default:
1562                 return -ENOIOCTLCMD;
1563         }
1564 
1565         return 0;
1566 }
1567 EXPORT_SYMBOL(udp_ioctl);
1568 
1569 struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
1570                                int noblock, int *peeked, int *off, int *err)
1571 {
1572         struct sk_buff_head *sk_queue = &sk->sk_receive_queue;
1573         struct sk_buff_head *queue;
1574         struct sk_buff *last;
1575         long timeo;
1576         int error;
1577 
1578         queue = &udp_sk(sk)->reader_queue;
1579         flags |= noblock ? MSG_DONTWAIT : 0;
1580         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1581         do {
1582                 struct sk_buff *skb;
1583 
1584                 error = sock_error(sk);
1585                 if (error)
1586                         break;
1587 
1588                 error = -EAGAIN;
1589                 *peeked = 0;
1590                 do {
1591                         spin_lock_bh(&queue->lock);
1592                         skb = __skb_try_recv_from_queue(sk, queue, flags,
1593                                                         udp_skb_destructor,
1594                                                         peeked, off, err,
1595                                                         &last);
1596                         if (skb) {
1597                                 spin_unlock_bh(&queue->lock);
1598                                 return skb;
1599                         }
1600 
1601                         if (skb_queue_empty(sk_queue)) {
1602                                 spin_unlock_bh(&queue->lock);
1603                                 goto busy_check;
1604                         }
1605 
1606                         /* refill the reader queue and walk it again
1607                          * keep both queues locked to avoid re-acquiring
1608                          * the sk_receive_queue lock if fwd memory scheduling
1609                          * is needed.
1610                          */
1611                         spin_lock(&sk_queue->lock);
1612                         skb_queue_splice_tail_init(sk_queue, queue);
1613 
1614                         skb = __skb_try_recv_from_queue(sk, queue, flags,
1615                                                         udp_skb_dtor_locked,
1616                                                         peeked, off, err,
1617                                                         &last);
1618                         spin_unlock(&sk_queue->lock);
1619                         spin_unlock_bh(&queue->lock);
1620                         if (skb)
1621                                 return skb;
1622 
1623 busy_check:
1624                         if (!sk_can_busy_loop(sk))
1625                                 break;
1626 
1627                         sk_busy_loop(sk, flags & MSG_DONTWAIT);
1628                 } while (!skb_queue_empty(sk_queue));
1629 
1630                 /* sk_queue is empty, reader_queue may contain peeked packets */
1631         } while (timeo &&
1632                  !__skb_wait_for_more_packets(sk, &error, &timeo,
1633                                               (struct sk_buff *)sk_queue));
1634 
1635         *err = error;
1636         return NULL;
1637 }
1638 EXPORT_SYMBOL(__skb_recv_udp);
1639 
1640 /*
1641  *      This should be easy, if there is something there we
1642  *      return it, otherwise we block.
1643  */
1644 
1645 int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
1646                 int flags, int *addr_len)
1647 {
1648         struct inet_sock *inet = inet_sk(sk);
1649         DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
1650         struct sk_buff *skb;
1651         unsigned int ulen, copied;
1652         int peeked, peeking, off;
1653         int err;
1654         int is_udplite = IS_UDPLITE(sk);
1655         bool checksum_valid = false;
1656 
1657         if (flags & MSG_ERRQUEUE)
1658                 return ip_recv_error(sk, msg, len, addr_len);
1659 
1660 try_again:
1661         peeking = flags & MSG_PEEK;
1662         off = sk_peek_offset(sk, flags);
1663         skb = __skb_recv_udp(sk, flags, noblock, &peeked, &off, &err);
1664         if (!skb)
1665                 return err;
1666         if (ccs_socket_post_recvmsg_permission(sk, skb, flags))
1667                 return -EAGAIN; /* Hope less harmful than -EPERM. */
1668 
1669         ulen = udp_skb_len(skb);
1670         copied = len;
1671         if (copied > ulen - off)
1672                 copied = ulen - off;
1673         else if (copied < ulen)
1674                 msg->msg_flags |= MSG_TRUNC;
1675 
1676         /*
1677          * If checksum is needed at all, try to do it while copying the
1678          * data.  If the data is truncated, or if we only want a partial
1679          * coverage checksum (UDP-Lite), do it before the copy.
1680          */
1681 
1682         if (copied < ulen || peeking ||
1683             (is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
1684                 checksum_valid = udp_skb_csum_unnecessary(skb) ||
1685                                 !__udp_lib_checksum_complete(skb);
1686                 if (!checksum_valid)
1687                         goto csum_copy_err;
1688         }
1689 
1690         if (checksum_valid || udp_skb_csum_unnecessary(skb)) {
1691                 if (udp_skb_is_linear(skb))
1692                         err = copy_linear_skb(skb, copied, off, &msg->msg_iter);
1693                 else
1694                         err = skb_copy_datagram_msg(skb, off, msg, copied);
1695         } else {
1696                 err = skb_copy_and_csum_datagram_msg(skb, off, msg);
1697 
1698                 if (err == -EINVAL)
1699                         goto csum_copy_err;
1700         }
1701 
1702         if (unlikely(err)) {
1703                 if (!peeked) {
1704                         atomic_inc(&sk->sk_drops);
1705                         UDP_INC_STATS(sock_net(sk),
1706                                       UDP_MIB_INERRORS, is_udplite);
1707                 }
1708                 kfree_skb(skb);
1709                 return err;
1710         }
1711 
1712         if (!peeked)
1713                 UDP_INC_STATS(sock_net(sk),
1714                               UDP_MIB_INDATAGRAMS, is_udplite);
1715 
1716         sock_recv_ts_and_drops(msg, sk, skb);
1717 
1718         /* Copy the address. */
1719         if (sin) {
1720                 sin->sin_family = AF_INET;
1721                 sin->sin_port = udp_hdr(skb)->source;
1722                 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
1723                 memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
1724                 *addr_len = sizeof(*sin);
1725         }
1726         if (inet->cmsg_flags)
1727                 ip_cmsg_recv_offset(msg, sk, skb, sizeof(struct udphdr), off);
1728 
1729         err = copied;
1730         if (flags & MSG_TRUNC)
1731                 err = ulen;
1732 
1733         skb_consume_udp(sk, skb, peeking ? -err : err);
1734         return err;
1735 
1736 csum_copy_err:
1737         if (!__sk_queue_drop_skb(sk, &udp_sk(sk)->reader_queue, skb, flags,
1738                                  udp_skb_destructor)) {
1739                 UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
1740                 UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1741         }
1742         kfree_skb(skb);
1743 
1744         /* starting over for a new packet, but check if we need to yield */
1745         cond_resched();
1746         msg->msg_flags &= ~MSG_TRUNC;
1747         goto try_again;
1748 }
1749 
1750 int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
1751 {
1752         /* This check is replicated from __ip4_datagram_connect() and
1753          * intended to prevent BPF program called below from accessing bytes
1754          * that are out of the bound specified by user in addr_len.
1755          */
1756         if (addr_len < sizeof(struct sockaddr_in))
1757                 return -EINVAL;
1758 
1759         return BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr);
1760 }
1761 EXPORT_SYMBOL(udp_pre_connect);
1762 
1763 int __udp_disconnect(struct sock *sk, int flags)
1764 {
1765         struct inet_sock *inet = inet_sk(sk);
1766         /*
1767          *      1003.1g - break association.
1768          */
1769 
1770         sk->sk_state = TCP_CLOSE;
1771         inet->inet_daddr = 0;
1772         inet->inet_dport = 0;
1773         sock_rps_reset_rxhash(sk);
1774         sk->sk_bound_dev_if = 0;
1775         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1776                 inet_reset_saddr(sk);
1777 
1778         if (!(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) {
1779                 sk->sk_prot->unhash(sk);
1780                 inet->inet_sport = 0;
1781         }
1782         sk_dst_reset(sk);
1783         return 0;
1784 }
1785 EXPORT_SYMBOL(__udp_disconnect);
1786 
1787 int udp_disconnect(struct sock *sk, int flags)
1788 {
1789         lock_sock(sk);
1790         __udp_disconnect(sk, flags);
1791         release_sock(sk);
1792         return 0;
1793 }
1794 EXPORT_SYMBOL(udp_disconnect);
1795 
1796 void udp_lib_unhash(struct sock *sk)
1797 {
1798         if (sk_hashed(sk)) {
1799                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
1800                 struct udp_hslot *hslot, *hslot2;
1801 
1802                 hslot  = udp_hashslot(udptable, sock_net(sk),
1803                                       udp_sk(sk)->udp_port_hash);
1804                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
1805 
1806                 spin_lock_bh(&hslot->lock);
1807                 if (rcu_access_pointer(sk->sk_reuseport_cb))
1808                         reuseport_detach_sock(sk);
1809                 if (sk_del_node_init_rcu(sk)) {
1810                         hslot->count--;
1811                         inet_sk(sk)->inet_num = 0;
1812                         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
1813 
1814                         spin_lock(&hslot2->lock);
1815                         hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
1816                         hslot2->count--;
1817                         spin_unlock(&hslot2->lock);
1818                 }
1819                 spin_unlock_bh(&hslot->lock);
1820         }
1821 }
1822 EXPORT_SYMBOL(udp_lib_unhash);
1823 
1824 /*
1825  * inet_rcv_saddr was changed, we must rehash secondary hash
1826  */
1827 void udp_lib_rehash(struct sock *sk, u16 newhash)
1828 {
1829         if (sk_hashed(sk)) {
1830                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
1831                 struct udp_hslot *hslot, *hslot2, *nhslot2;
1832 
1833                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
1834                 nhslot2 = udp_hashslot2(udptable, newhash);
1835                 udp_sk(sk)->udp_portaddr_hash = newhash;
1836 
1837                 if (hslot2 != nhslot2 ||
1838                     rcu_access_pointer(sk->sk_reuseport_cb)) {
1839                         hslot = udp_hashslot(udptable, sock_net(sk),
1840                                              udp_sk(sk)->udp_port_hash);
1841                         /* we must lock primary chain too */
1842                         spin_lock_bh(&hslot->lock);
1843                         if (rcu_access_pointer(sk->sk_reuseport_cb))
1844                                 reuseport_detach_sock(sk);
1845 
1846                         if (hslot2 != nhslot2) {
1847                                 spin_lock(&hslot2->lock);
1848                                 hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
1849                                 hslot2->count--;
1850                                 spin_unlock(&hslot2->lock);
1851 
1852                                 spin_lock(&nhslot2->lock);
1853                                 hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
1854                                                          &nhslot2->head);
1855                                 nhslot2->count++;
1856                                 spin_unlock(&nhslot2->lock);
1857                         }
1858 
1859                         spin_unlock_bh(&hslot->lock);
1860                 }
1861         }
1862 }
1863 EXPORT_SYMBOL(udp_lib_rehash);
1864 
1865 static void udp_v4_rehash(struct sock *sk)
1866 {
1867         u16 new_hash = ipv4_portaddr_hash(sock_net(sk),
1868                                           inet_sk(sk)->inet_rcv_saddr,
1869                                           inet_sk(sk)->inet_num);
1870         udp_lib_rehash(sk, new_hash);
1871 }
1872 
1873 static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
1874 {
1875         int rc;
1876 
1877         if (inet_sk(sk)->inet_daddr) {
1878                 sock_rps_save_rxhash(sk, skb);
1879                 sk_mark_napi_id(sk, skb);
1880                 sk_incoming_cpu_update(sk);
1881         } else {
1882                 sk_mark_napi_id_once(sk, skb);
1883         }
1884 
1885         rc = __udp_enqueue_schedule_skb(sk, skb);
1886         if (rc < 0) {
1887                 int is_udplite = IS_UDPLITE(sk);
1888 
1889                 /* Note that an ENOMEM error is charged twice */
1890                 if (rc == -ENOMEM)
1891                         UDP_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS,
1892                                         is_udplite);
1893                 UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1894                 kfree_skb(skb);
1895                 trace_udp_fail_queue_rcv_skb(rc, sk);
1896                 return -1;
1897         }
1898 
1899         return 0;
1900 }
1901 
1902 DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
1903 void udp_encap_enable(void)
1904 {
1905         static_branch_enable(&udp_encap_needed_key);
1906 }
1907 EXPORT_SYMBOL(udp_encap_enable);
1908 
1909 /* returns:
1910  *  -1: error
1911  *   0: success
1912  *  >0: "udp encap" protocol resubmission
1913  *
1914  * Note that in the success and error cases, the skb is assumed to
1915  * have either been requeued or freed.
1916  */
1917 static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
1918 {
1919         struct udp_sock *up = udp_sk(sk);
1920         int is_udplite = IS_UDPLITE(sk);
1921 
1922         /*
1923          *      Charge it to the socket, dropping if the queue is full.
1924          */
1925         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1926                 goto drop;
1927         nf_reset(skb);
1928 
1929         if (static_branch_unlikely(&udp_encap_needed_key) && up->encap_type) {
1930                 int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
1931 
1932                 /*
1933                  * This is an encapsulation socket so pass the skb to
1934                  * the socket's udp_encap_rcv() hook. Otherwise, just
1935                  * fall through and pass this up the UDP socket.
1936                  * up->encap_rcv() returns the following value:
1937                  * =0 if skb was successfully passed to the encap
1938                  *    handler or was discarded by it.
1939                  * >0 if skb should be passed on to UDP.
1940                  * <0 if skb should be resubmitted as proto -N
1941                  */
1942 
1943                 /* if we're overly short, let UDP handle it */
1944                 encap_rcv = READ_ONCE(up->encap_rcv);
1945                 if (encap_rcv) {
1946                         int ret;
1947 
1948                         /* Verify checksum before giving to encap */
1949                         if (udp_lib_checksum_complete(skb))
1950                                 goto csum_error;
1951 
1952                         ret = encap_rcv(sk, skb);
1953                         if (ret <= 0) {
1954                                 __UDP_INC_STATS(sock_net(sk),
1955                                                 UDP_MIB_INDATAGRAMS,
1956                                                 is_udplite);
1957                                 return -ret;
1958                         }
1959                 }
1960 
1961                 /* FALLTHROUGH -- it's a UDP Packet */
1962         }
1963 
1964         /*
1965          *      UDP-Lite specific tests, ignored on UDP sockets
1966          */
1967         if ((is_udplite & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
1968 
1969                 /*
1970                  * MIB statistics other than incrementing the error count are
1971                  * disabled for the following two types of errors: these depend
1972                  * on the application settings, not on the functioning of the
1973                  * protocol stack as such.
1974                  *
1975                  * RFC 3828 here recommends (sec 3.3): "There should also be a
1976                  * way ... to ... at least let the receiving application block
1977                  * delivery of packets with coverage values less than a value
1978                  * provided by the application."
1979                  */
1980                 if (up->pcrlen == 0) {          /* full coverage was set  */
1981                         net_dbg_ratelimited("UDPLite: partial coverage %d while full coverage %d requested\n",
1982                                             UDP_SKB_CB(skb)->cscov, skb->len);
1983                         goto drop;
1984                 }
1985                 /* The next case involves violating the min. coverage requested
1986                  * by the receiver. This is subtle: if receiver wants x and x is
1987                  * greater than the buffersize/MTU then receiver will complain
1988                  * that it wants x while sender emits packets of smaller size y.
1989                  * Therefore the above ...()->partial_cov statement is essential.
1990                  */
1991                 if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
1992                         net_dbg_ratelimited("UDPLite: coverage %d too small, need min %d\n",
1993                                             UDP_SKB_CB(skb)->cscov, up->pcrlen);
1994                         goto drop;
1995                 }
1996         }
1997 
1998         prefetch(&sk->sk_rmem_alloc);
1999         if (rcu_access_pointer(sk->sk_filter) &&
2000             udp_lib_checksum_complete(skb))
2001                         goto csum_error;
2002 
2003         if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr)))
2004                 goto drop;
2005 
2006         udp_csum_pull_header(skb);
2007 
2008         ipv4_pktinfo_prepare(sk, skb);
2009         return __udp_queue_rcv_skb(sk, skb);
2010 
2011 csum_error:
2012         __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
2013 drop:
2014         __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
2015         atomic_inc(&sk->sk_drops);
2016         kfree_skb(skb);
2017         return -1;
2018 }
2019 
2020 /* For TCP sockets, sk_rx_dst is protected by socket lock
2021  * For UDP, we use xchg() to guard against concurrent changes.
2022  */
2023 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
2024 {
2025         struct dst_entry *old;
2026 
2027         if (dst_hold_safe(dst)) {
2028                 old = xchg(&sk->sk_rx_dst, dst);
2029                 dst_release(old);
2030                 return old != dst;
2031         }
2032         return false;
2033 }
2034 EXPORT_SYMBOL(udp_sk_rx_dst_set);
2035 
2036 /*
2037  *      Multicasts and broadcasts go to each listener.
2038  *
2039  *      Note: called only from the BH handler context.
2040  */
2041 static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
2042                                     struct udphdr  *uh,
2043                                     __be32 saddr, __be32 daddr,
2044                                     struct udp_table *udptable,
2045                                     int proto)
2046 {
2047         struct sock *sk, *first = NULL;
2048         unsigned short hnum = ntohs(uh->dest);
2049         struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum);
2050         unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
2051         unsigned int offset = offsetof(typeof(*sk), sk_node);
2052         int dif = skb->dev->ifindex;
2053         int sdif = inet_sdif(skb);
2054         struct hlist_node *node;
2055         struct sk_buff *nskb;
2056 
2057         if (use_hash2) {
2058                 hash2_any = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum) &
2059                             udptable->mask;
2060                 hash2 = ipv4_portaddr_hash(net, daddr, hnum) & udptable->mask;
2061 start_lookup:
2062                 hslot = &udptable->hash2[hash2];
2063                 offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node);
2064         }
2065 
2066         sk_for_each_entry_offset_rcu(sk, node, &hslot->head, offset) {
2067                 if (!__udp_is_mcast_sock(net, sk, uh->dest, daddr,
2068                                          uh->source, saddr, dif, sdif, hnum))
2069                         continue;
2070 
2071                 if (!first) {
2072                         first = sk;
2073                         continue;
2074                 }
2075                 nskb = skb_clone(skb, GFP_ATOMIC);
2076 
2077                 if (unlikely(!nskb)) {
2078                         atomic_inc(&sk->sk_drops);
2079                         __UDP_INC_STATS(net, UDP_MIB_RCVBUFERRORS,
2080                                         IS_UDPLITE(sk));
2081                         __UDP_INC_STATS(net, UDP_MIB_INERRORS,
2082                                         IS_UDPLITE(sk));
2083                         continue;
2084                 }
2085                 if (udp_queue_rcv_skb(sk, nskb) > 0)
2086                         consume_skb(nskb);
2087         }
2088 
2089         /* Also lookup *:port if we are using hash2 and haven't done so yet. */
2090         if (use_hash2 && hash2 != hash2_any) {
2091                 hash2 = hash2_any;
2092                 goto start_lookup;
2093         }
2094 
2095         if (first) {
2096                 if (udp_queue_rcv_skb(first, skb) > 0)
2097                         consume_skb(skb);
2098         } else {
2099                 kfree_skb(skb);
2100                 __UDP_INC_STATS(net, UDP_MIB_IGNOREDMULTI,
2101                                 proto == IPPROTO_UDPLITE);
2102         }
2103         return 0;
2104 }
2105 
2106 /* Initialize UDP checksum. If exited with zero value (success),
2107  * CHECKSUM_UNNECESSARY means, that no more checks are required.
2108  * Otherwise, csum completion requires chacksumming packet body,
2109  * including udp header and folding it to skb->csum.
2110  */
2111 static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,
2112                                  int proto)
2113 {
2114         int err;
2115 
2116         UDP_SKB_CB(skb)->partial_cov = 0;
2117         UDP_SKB_CB(skb)->cscov = skb->len;
2118 
2119         if (proto == IPPROTO_UDPLITE) {
2120                 err = udplite_checksum_init(skb, uh);
2121                 if (err)
2122                         return err;
2123 
2124                 if (UDP_SKB_CB(skb)->partial_cov) {
2125                         skb->csum = inet_compute_pseudo(skb, proto);
2126                         return 0;
2127                 }
2128         }
2129 
2130         /* Note, we are only interested in != 0 or == 0, thus the
2131          * force to int.
2132          */
2133         err = (__force int)skb_checksum_init_zero_check(skb, proto, uh->check,
2134                                                         inet_compute_pseudo);
2135         if (err)
2136                 return err;
2137 
2138         if (skb->ip_summed == CHECKSUM_COMPLETE && !skb->csum_valid) {
2139                 /* If SW calculated the value, we know it's bad */
2140                 if (skb->csum_complete_sw)
2141                         return 1;
2142 
2143                 /* HW says the value is bad. Let's validate that.
2144                  * skb->csum is no longer the full packet checksum,
2145                  * so don't treat it as such.
2146                  */
2147                 skb_checksum_complete_unset(skb);
2148         }
2149 
2150         return 0;
2151 }
2152 
2153 /* wrapper for udp_queue_rcv_skb tacking care of csum conversion and
2154  * return code conversion for ip layer consumption
2155  */
2156 static int udp_unicast_rcv_skb(struct sock *sk, struct sk_buff *skb,
2157                                struct udphdr *uh)
2158 {
2159         int ret;
2160 
2161         if (inet_get_convert_csum(sk) && uh->check && !IS_UDPLITE(sk))
2162                 skb_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
2163                                          inet_compute_pseudo);
2164 
2165         ret = udp_queue_rcv_skb(sk, skb);
2166 
2167         /* a return value > 0 means to resubmit the input, but
2168          * it wants the return to be -protocol, or 0
2169          */
2170         if (ret > 0)
2171                 return -ret;
2172         return 0;
2173 }
2174 
2175 /*
2176  *      All we need to do is get the socket, and then do a checksum.
2177  */
2178 
2179 int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
2180                    int proto)
2181 {
2182         struct sock *sk;
2183         struct udphdr *uh;
2184         unsigned short ulen;
2185         struct rtable *rt = skb_rtable(skb);
2186         __be32 saddr, daddr;
2187         struct net *net = dev_net(skb->dev);
2188 
2189         /*
2190          *  Validate the packet.
2191          */
2192         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
2193                 goto drop;              /* No space for header. */
2194 
2195         uh   = udp_hdr(skb);
2196         ulen = ntohs(uh->len);
2197         saddr = ip_hdr(skb)->saddr;
2198         daddr = ip_hdr(skb)->daddr;
2199 
2200         if (ulen > skb->len)
2201                 goto short_packet;
2202 
2203         if (proto == IPPROTO_UDP) {
2204                 /* UDP validates ulen. */
2205                 if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen))
2206                         goto short_packet;
2207                 uh = udp_hdr(skb);
2208         }
2209 
2210         if (udp4_csum_init(skb, uh, proto))
2211                 goto csum_error;
2212 
2213         sk = skb_steal_sock(skb);
2214         if (sk) {
2215                 struct dst_entry *dst = skb_dst(skb);
2216                 int ret;
2217 
2218                 if (unlikely(sk->sk_rx_dst != dst))
2219                         udp_sk_rx_dst_set(sk, dst);
2220 
2221                 ret = udp_unicast_rcv_skb(sk, skb, uh);
2222                 sock_put(sk);
2223                 return ret;
2224         }
2225 
2226         if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
2227                 return __udp4_lib_mcast_deliver(net, skb, uh,
2228                                                 saddr, daddr, udptable, proto);
2229 
2230         sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
2231         if (sk)
2232                 return udp_unicast_rcv_skb(sk, skb, uh);
2233 
2234         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
2235                 goto drop;
2236         nf_reset(skb);
2237 
2238         /* No socket. Drop packet silently, if checksum is wrong */
2239         if (udp_lib_checksum_complete(skb))
2240                 goto csum_error;
2241 
2242         __UDP_INC_STATS(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
2243         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
2244 
2245         /*
2246          * Hmm.  We got an UDP packet to a port to which we
2247          * don't wanna listen.  Ignore it.
2248          */
2249         kfree_skb(skb);
2250         return 0;
2251 
2252 short_packet:
2253         net_dbg_ratelimited("UDP%s: short packet: From %pI4:%u %d/%d to %pI4:%u\n",
2254                             proto == IPPROTO_UDPLITE ? "Lite" : "",
2255                             &saddr, ntohs(uh->source),
2256                             ulen, skb->len,
2257                             &daddr, ntohs(uh->dest));
2258         goto drop;
2259 
2260 csum_error:
2261         /*
2262          * RFC1122: OK.  Discards the bad packet silently (as far as
2263          * the network is concerned, anyway) as per 4.1.3.4 (MUST).
2264          */
2265         net_dbg_ratelimited("UDP%s: bad checksum. From %pI4:%u to %pI4:%u ulen %d\n",
2266                             proto == IPPROTO_UDPLITE ? "Lite" : "",
2267                             &saddr, ntohs(uh->source), &daddr, ntohs(uh->dest),
2268                             ulen);
2269         __UDP_INC_STATS(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE);
2270 drop:
2271         __UDP_INC_STATS(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
2272         kfree_skb(skb);
2273         return 0;
2274 }
2275 
2276 /* We can only early demux multicast if there is a single matching socket.
2277  * If more than one socket found returns NULL
2278  */
2279 static struct sock *__udp4_lib_mcast_demux_lookup(struct net *net,
2280                                                   __be16 loc_port, __be32 loc_addr,
2281                                                   __be16 rmt_port, __be32 rmt_addr,
2282                                                   int dif, int sdif)
2283 {
2284         struct sock *sk, *result;
2285         unsigned short hnum = ntohs(loc_port);
2286         unsigned int slot = udp_hashfn(net, hnum, udp_table.mask);
2287         struct udp_hslot *hslot = &udp_table.hash[slot];
2288 
2289         /* Do not bother scanning a too big list */
2290         if (hslot->count > 10)
2291                 return NULL;
2292 
2293         result = NULL;
2294         sk_for_each_rcu(sk, &hslot->head) {
2295                 if (__udp_is_mcast_sock(net, sk, loc_port, loc_addr,
2296                                         rmt_port, rmt_addr, dif, sdif, hnum)) {
2297                         if (result)
2298                                 return NULL;
2299                         result = sk;
2300                 }
2301         }
2302 
2303         return result;
2304 }
2305 
2306 /* For unicast we should only early demux connected sockets or we can
2307  * break forwarding setups.  The chains here can be long so only check
2308  * if the first socket is an exact match and if not move on.
2309  */
2310 static struct sock *__udp4_lib_demux_lookup(struct net *net,
2311                                             __be16 loc_port, __be32 loc_addr,
2312                                             __be16 rmt_port, __be32 rmt_addr,
2313                                             int dif, int sdif)
2314 {
2315         unsigned short hnum = ntohs(loc_port);
2316         unsigned int hash2 = ipv4_portaddr_hash(net, loc_addr, hnum);
2317         unsigned int slot2 = hash2 & udp_table.mask;
2318         struct udp_hslot *hslot2 = &udp_table.hash2[slot2];
2319         INET_ADDR_COOKIE(acookie, rmt_addr, loc_addr);
2320         const __portpair ports = INET_COMBINED_PORTS(rmt_port, hnum);
2321         struct sock *sk;
2322 
2323         udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
2324                 if (INET_MATCH(sk, net, acookie, rmt_addr,
2325                                loc_addr, ports, dif, sdif))
2326                         return sk;
2327                 /* Only check first socket in chain */
2328                 break;
2329         }
2330         return NULL;
2331 }
2332 
2333 int udp_v4_early_demux(struct sk_buff *skb)
2334 {
2335         struct net *net = dev_net(skb->dev);
2336         struct in_device *in_dev = NULL;
2337         const struct iphdr *iph;
2338         const struct udphdr *uh;
2339         struct sock *sk = NULL;
2340         struct dst_entry *dst;
2341         int dif = skb->dev->ifindex;
2342         int sdif = inet_sdif(skb);
2343         int ours;
2344 
2345         /* validate the packet */
2346         if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr)))
2347                 return 0;
2348 
2349         iph = ip_hdr(skb);
2350         uh = udp_hdr(skb);
2351 
2352         if (skb->pkt_type == PACKET_MULTICAST) {
2353                 in_dev = __in_dev_get_rcu(skb->dev);
2354 
2355                 if (!in_dev)
2356                         return 0;
2357 
2358                 ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
2359                                        iph->protocol);
2360                 if (!ours)
2361                         return 0;
2362 
2363                 sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr,
2364                                                    uh->source, iph->saddr,
2365                                                    dif, sdif);
2366         } else if (skb->pkt_type == PACKET_HOST) {
2367                 sk = __udp4_lib_demux_lookup(net, uh->dest, iph->daddr,
2368                                              uh->source, iph->saddr, dif, sdif);
2369         }
2370 
2371         if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
2372                 return 0;
2373 
2374         skb->sk = sk;
2375         skb->destructor = sock_efree;
2376         dst = READ_ONCE(sk->sk_rx_dst);
2377 
2378         if (dst)
2379                 dst = dst_check(dst, 0);
2380         if (dst) {
2381                 u32 itag = 0;
2382 
2383                 /* set noref for now.
2384                  * any place which wants to hold dst has to call
2385                  * dst_hold_safe()
2386                  */
2387                 skb_dst_set_noref(skb, dst);
2388 
2389                 /* for unconnected multicast sockets we need to validate
2390                  * the source on each packet
2391                  */
2392                 if (!inet_sk(sk)->inet_daddr && in_dev)
2393                         return ip_mc_validate_source(skb, iph->daddr,
2394                                                      iph->saddr, iph->tos,
2395                                                      skb->dev, in_dev, &itag);
2396         }
2397         return 0;
2398 }
2399 
2400 int udp_rcv(struct sk_buff *skb)
2401 {
2402         return __udp4_lib_rcv(skb, &udp_table, IPPROTO_UDP);
2403 }
2404 
2405 void udp_destroy_sock(struct sock *sk)
2406 {
2407         struct udp_sock *up = udp_sk(sk);
2408         bool slow = lock_sock_fast(sk);
2409         udp_flush_pending_frames(sk);
2410         unlock_sock_fast(sk, slow);
2411         if (static_branch_unlikely(&udp_encap_needed_key) && up->encap_type) {
2412                 void (*encap_destroy)(struct sock *sk);
2413                 encap_destroy = READ_ONCE(up->encap_destroy);
2414                 if (encap_destroy)
2415                         encap_destroy(sk);
2416         }
2417 }
2418 
2419 /*
2420  *      Socket option code for UDP
2421  */
2422 int udp_lib_setsockopt(struct sock *sk, int level, int optname,
2423                        char __user *optval, unsigned int optlen,
2424                        int (*push_pending_frames)(struct sock *))
2425 {
2426         struct udp_sock *up = udp_sk(sk);
2427         int val, valbool;
2428         int err = 0;
2429         int is_udplite = IS_UDPLITE(sk);
2430 
2431         if (optlen < sizeof(int))
2432                 return -EINVAL;
2433 
2434         if (get_user(val, (int __user *)optval))
2435                 return -EFAULT;
2436 
2437         valbool = val ? 1 : 0;
2438 
2439         switch (optname) {
2440         case UDP_CORK:
2441                 if (val != 0) {
2442                         up->corkflag = 1;
2443                 } else {
2444                         up->corkflag = 0;
2445                         lock_sock(sk);
2446                         push_pending_frames(sk);
2447                         release_sock(sk);
2448                 }
2449                 break;
2450 
2451         case UDP_ENCAP:
2452                 switch (val) {
2453                 case 0:
2454                 case UDP_ENCAP_ESPINUDP:
2455                 case UDP_ENCAP_ESPINUDP_NON_IKE:
2456                         up->encap_rcv = xfrm4_udp_encap_rcv;
2457                         /* FALLTHROUGH */
2458                 case UDP_ENCAP_L2TPINUDP:
2459                         up->encap_type = val;
2460                         udp_encap_enable();
2461                         break;
2462                 default:
2463                         err = -ENOPROTOOPT;
2464                         break;
2465                 }
2466                 break;
2467 
2468         case UDP_NO_CHECK6_TX:
2469                 up->no_check6_tx = valbool;
2470                 break;
2471 
2472         case UDP_NO_CHECK6_RX:
2473                 up->no_check6_rx = valbool;
2474                 break;
2475 
2476         case UDP_SEGMENT:
2477                 if (val < 0 || val > USHRT_MAX)
2478                         return -EINVAL;
2479                 up->gso_size = val;
2480                 break;
2481 
2482         /*
2483          *      UDP-Lite's partial checksum coverage (RFC 3828).
2484          */
2485         /* The sender sets actual checksum coverage length via this option.
2486          * The case coverage > packet length is handled by send module. */
2487         case UDPLITE_SEND_CSCOV:
2488                 if (!is_udplite)         /* Disable the option on UDP sockets */
2489                         return -ENOPROTOOPT;
2490                 if (val != 0 && val < 8) /* Illegal coverage: use default (8) */
2491                         val = 8;
2492                 else if (val > USHRT_MAX)
2493                         val = USHRT_MAX;
2494                 up->pcslen = val;
2495                 up->pcflag |= UDPLITE_SEND_CC;
2496                 break;
2497 
2498         /* The receiver specifies a minimum checksum coverage value. To make
2499          * sense, this should be set to at least 8 (as done below). If zero is
2500          * used, this again means full checksum coverage.                     */
2501         case UDPLITE_RECV_CSCOV:
2502                 if (!is_udplite)         /* Disable the option on UDP sockets */
2503                         return -ENOPROTOOPT;
2504                 if (val != 0 && val < 8) /* Avoid silly minimal values.       */
2505                         val = 8;
2506                 else if (val > USHRT_MAX)
2507                         val = USHRT_MAX;
2508                 up->pcrlen = val;
2509                 up->pcflag |= UDPLITE_RECV_CC;
2510                 break;
2511 
2512         default:
2513                 err = -ENOPROTOOPT;
2514                 break;
2515         }
2516 
2517         return err;
2518 }
2519 EXPORT_SYMBOL(udp_lib_setsockopt);
2520 
2521 int udp_setsockopt(struct sock *sk, int level, int optname,
2522                    char __user *optval, unsigned int optlen)
2523 {
2524         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2525                 return udp_lib_setsockopt(sk, level, optname, optval, optlen,
2526                                           udp_push_pending_frames);
2527         return ip_setsockopt(sk, level, optname, optval, optlen);
2528 }
2529 
2530 #ifdef CONFIG_COMPAT
2531 int compat_udp_setsockopt(struct sock *sk, int level, int optname,
2532                           char __user *optval, unsigned int optlen)
2533 {
2534         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2535                 return udp_lib_setsockopt(sk, level, optname, optval, optlen,
2536                                           udp_push_pending_frames);
2537         return compat_ip_setsockopt(sk, level, optname, optval, optlen);
2538 }
2539 #endif
2540 
2541 int udp_lib_getsockopt(struct sock *sk, int level, int optname,
2542                        char __user *optval, int __user *optlen)
2543 {
2544         struct udp_sock *up = udp_sk(sk);
2545         int val, len;
2546 
2547         if (get_user(len, optlen))
2548                 return -EFAULT;
2549 
2550         len = min_t(unsigned int, len, sizeof(int));
2551 
2552         if (len < 0)
2553                 return -EINVAL;
2554 
2555         switch (optname) {
2556         case UDP_CORK:
2557                 val = up->corkflag;
2558                 break;
2559 
2560         case UDP_ENCAP:
2561                 val = up->encap_type;
2562                 break;
2563 
2564         case UDP_NO_CHECK6_TX:
2565                 val = up->no_check6_tx;
2566                 break;
2567 
2568         case UDP_NO_CHECK6_RX:
2569                 val = up->no_check6_rx;
2570                 break;
2571 
2572         case UDP_SEGMENT:
2573                 val = up->gso_size;
2574                 break;
2575 
2576         /* The following two cannot be changed on UDP sockets, the return is
2577          * always 0 (which corresponds to the full checksum coverage of UDP). */
2578         case UDPLITE_SEND_CSCOV:
2579                 val = up->pcslen;
2580                 break;
2581 
2582         case UDPLITE_RECV_CSCOV:
2583                 val = up->pcrlen;
2584                 break;
2585 
2586         default:
2587                 return -ENOPROTOOPT;
2588         }
2589 
2590         if (put_user(len, optlen))
2591                 return -EFAULT;
2592         if (copy_to_user(optval, &val, len))
2593                 return -EFAULT;
2594         return 0;
2595 }
2596 EXPORT_SYMBOL(udp_lib_getsockopt);
2597 
2598 int udp_getsockopt(struct sock *sk, int level, int optname,
2599                    char __user *optval, int __user *optlen)
2600 {
2601         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2602                 return udp_lib_getsockopt(sk, level, optname, optval, optlen);
2603         return ip_getsockopt(sk, level, optname, optval, optlen);
2604 }
2605 
2606 #ifdef CONFIG_COMPAT
2607 int compat_udp_getsockopt(struct sock *sk, int level, int optname,
2608                                  char __user *optval, int __user *optlen)
2609 {
2610         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2611                 return udp_lib_getsockopt(sk, level, optname, optval, optlen);
2612         return compat_ip_getsockopt(sk, level, optname, optval, optlen);
2613 }
2614 #endif
2615 /**
2616  *      udp_poll - wait for a UDP event.
2617  *      @file - file struct
2618  *      @sock - socket
2619  *      @wait - poll table
2620  *
2621  *      This is same as datagram poll, except for the special case of
2622  *      blocking sockets. If application is using a blocking fd
2623  *      and a packet with checksum error is in the queue;
2624  *      then it could get return from select indicating data available
2625  *      but then block when reading it. Add special case code
2626  *      to work around these arguably broken applications.
2627  */
2628 __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait)
2629 {
2630         __poll_t mask = datagram_poll(file, sock, wait);
2631         struct sock *sk = sock->sk;
2632 
2633         if (!skb_queue_empty(&udp_sk(sk)->reader_queue))
2634                 mask |= EPOLLIN | EPOLLRDNORM;
2635 
2636         /* Check for false positives due to checksum errors */
2637         if ((mask & EPOLLRDNORM) && !(file->f_flags & O_NONBLOCK) &&
2638             !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1)
2639                 mask &= ~(EPOLLIN | EPOLLRDNORM);
2640 
2641         return mask;
2642 
2643 }
2644 EXPORT_SYMBOL(udp_poll);
2645 
2646 int udp_abort(struct sock *sk, int err)
2647 {
2648         lock_sock(sk);
2649 
2650         sk->sk_err = err;
2651         sk->sk_error_report(sk);
2652         __udp_disconnect(sk, 0);
2653 
2654         release_sock(sk);
2655 
2656         return 0;
2657 }
2658 EXPORT_SYMBOL_GPL(udp_abort);
2659 
2660 struct proto udp_prot = {
2661         .name                   = "UDP",
2662         .owner                  = THIS_MODULE,
2663         .close                  = udp_lib_close,
2664         .pre_connect            = udp_pre_connect,
2665         .connect                = ip4_datagram_connect,
2666         .disconnect             = udp_disconnect,
2667         .ioctl                  = udp_ioctl,
2668         .init                   = udp_init_sock,
2669         .destroy                = udp_destroy_sock,
2670         .setsockopt             = udp_setsockopt,
2671         .getsockopt             = udp_getsockopt,
2672         .sendmsg                = udp_sendmsg,
2673         .recvmsg                = udp_recvmsg,
2674         .sendpage               = udp_sendpage,
2675         .release_cb             = ip4_datagram_release_cb,
2676         .hash                   = udp_lib_hash,
2677         .unhash                 = udp_lib_unhash,
2678         .rehash                 = udp_v4_rehash,
2679         .get_port               = udp_v4_get_port,
2680         .memory_allocated       = &udp_memory_allocated,
2681         .sysctl_mem             = sysctl_udp_mem,
2682         .sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
2683         .sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
2684         .obj_size               = sizeof(struct udp_sock),
2685         .h.udp_table            = &udp_table,
2686 #ifdef CONFIG_COMPAT
2687         .compat_setsockopt      = compat_udp_setsockopt,
2688         .compat_getsockopt      = compat_udp_getsockopt,
2689 #endif
2690         .diag_destroy           = udp_abort,
2691 };
2692 EXPORT_SYMBOL(udp_prot);
2693 
2694 /* ------------------------------------------------------------------------ */
2695 #ifdef CONFIG_PROC_FS
2696 
2697 static struct sock *udp_get_first(struct seq_file *seq, int start)
2698 {
2699         struct sock *sk;
2700         struct udp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file));
2701         struct udp_iter_state *state = seq->private;
2702         struct net *net = seq_file_net(seq);
2703 
2704         for (state->bucket = start; state->bucket <= afinfo->udp_table->mask;
2705              ++state->bucket) {
2706                 struct udp_hslot *hslot = &afinfo->udp_table->hash[state->bucket];
2707 
2708                 if (hlist_empty(&hslot->head))
2709                         continue;
2710 
2711                 spin_lock_bh(&hslot->lock);
2712                 sk_for_each(sk, &hslot->head) {
2713                         if (!net_eq(sock_net(sk), net))
2714                                 continue;
2715                         if (sk->sk_family == afinfo->family)
2716                                 goto found;
2717                 }
2718                 spin_unlock_bh(&hslot->lock);
2719         }
2720         sk = NULL;
2721 found:
2722         return sk;
2723 }
2724 
2725 static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
2726 {
2727         struct udp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file));
2728         struct udp_iter_state *state = seq->private;
2729         struct net *net = seq_file_net(seq);
2730 
2731         do {
2732                 sk = sk_next(sk);
2733         } while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != afinfo->family));
2734 
2735         if (!sk) {
2736                 if (state->bucket <= afinfo->udp_table->mask)
2737                         spin_unlock_bh(&afinfo->udp_table->hash[state->bucket].lock);
2738                 return udp_get_first(seq, state->bucket + 1);
2739         }
2740         return sk;
2741 }
2742 
2743 static struct sock *udp_get_idx(struct seq_file *seq, loff_t pos)
2744 {
2745         struct sock *sk = udp_get_first(seq, 0);
2746 
2747         if (sk)
2748                 while (pos && (sk = udp_get_next(seq, sk)) != NULL)
2749                         --pos;
2750         return pos ? NULL : sk;
2751 }
2752 
2753 void *udp_seq_start(struct seq_file *seq, loff_t *pos)
2754 {
2755         struct udp_iter_state *state = seq->private;
2756         state->bucket = MAX_UDP_PORTS;
2757 
2758         return *pos ? udp_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
2759 }
2760 EXPORT_SYMBOL(udp_seq_start);
2761 
2762 void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2763 {
2764         struct sock *sk;
2765 
2766         if (v == SEQ_START_TOKEN)
2767                 sk = udp_get_idx(seq, 0);
2768         else
2769                 sk = udp_get_next(seq, v);
2770 
2771         ++*pos;
2772         return sk;
2773 }
2774 EXPORT_SYMBOL(udp_seq_next);
2775 
2776 void udp_seq_stop(struct seq_file *seq, void *v)
2777 {
2778         struct udp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file));
2779         struct udp_iter_state *state = seq->private;
2780 
2781         if (state->bucket <= afinfo->udp_table->mask)
2782                 spin_unlock_bh(&afinfo->udp_table->hash[state->bucket].lock);
2783 }
2784 EXPORT_SYMBOL(udp_seq_stop);
2785 
2786 /* ------------------------------------------------------------------------ */
2787 static void udp4_format_sock(struct sock *sp, struct seq_file *f,
2788                 int bucket)
2789 {
2790         struct inet_sock *inet = inet_sk(sp);
2791         __be32 dest = inet->inet_daddr;
2792         __be32 src  = inet->inet_rcv_saddr;
2793         __u16 destp       = ntohs(inet->inet_dport);
2794         __u16 srcp        = ntohs(inet->inet_sport);
2795 
2796         seq_printf(f, "%5d: %08X:%04X %08X:%04X"
2797                 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
2798                 bucket, src, srcp, dest, destp, sp->sk_state,
2799                 sk_wmem_alloc_get(sp),
2800                 udp_rqueue_get(sp),
2801                 0, 0L, 0,
2802                 from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
2803                 0, sock_i_ino(sp),
2804                 refcount_read(&sp->sk_refcnt), sp,
2805                 atomic_read(&sp->sk_drops));
2806 }
2807 
2808 int udp4_seq_show(struct seq_file *seq, void *v)
2809 {
2810         seq_setwidth(seq, 127);
2811         if (v == SEQ_START_TOKEN)
2812                 seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
2813                            "rx_queue tr tm->when retrnsmt   uid  timeout "
2814                            "inode ref pointer drops");
2815         else {
2816                 struct udp_iter_state *state = seq->private;
2817 
2818                 udp4_format_sock(v, seq, state->bucket);
2819         }
2820         seq_pad(seq, '\n');
2821         return 0;
2822 }
2823 
2824 const struct seq_operations udp_seq_ops = {
2825         .start          = udp_seq_start,
2826         .next           = udp_seq_next,
2827         .stop           = udp_seq_stop,
2828         .show           = udp4_seq_show,
2829 };
2830 EXPORT_SYMBOL(udp_seq_ops);
2831 
2832 static struct udp_seq_afinfo udp4_seq_afinfo = {
2833         .family         = AF_INET,
2834         .udp_table      = &udp_table,
2835 };
2836 
2837 static int __net_init udp4_proc_init_net(struct net *net)
2838 {
2839         if (!proc_create_net_data("udp", 0444, net->proc_net, &udp_seq_ops,
2840                         sizeof(struct udp_iter_state), &udp4_seq_afinfo))
2841                 return -ENOMEM;
2842         return 0;
2843 }
2844 
2845 static void __net_exit udp4_proc_exit_net(struct net *net)
2846 {
2847         remove_proc_entry("udp", net->proc_net);
2848 }
2849 
2850 static struct pernet_operations udp4_net_ops = {
2851         .init = udp4_proc_init_net,
2852         .exit = udp4_proc_exit_net,
2853 };
2854 
2855 int __init udp4_proc_init(void)
2856 {
2857         return register_pernet_subsys(&udp4_net_ops);
2858 }
2859 
2860 void udp4_proc_exit(void)
2861 {
2862         unregister_pernet_subsys(&udp4_net_ops);
2863 }
2864 #endif /* CONFIG_PROC_FS */
2865 
2866 static __initdata unsigned long uhash_entries;
2867 static int __init set_uhash_entries(char *str)
2868 {
2869         ssize_t ret;
2870 
2871         if (!str)
2872                 return 0;
2873 
2874         ret = kstrtoul(str, 0, &uhash_entries);
2875         if (ret)
2876                 return 0;
2877 
2878         if (uhash_entries && uhash_entries < UDP_HTABLE_SIZE_MIN)
2879                 uhash_entries = UDP_HTABLE_SIZE_MIN;
2880         return 1;
2881 }
2882 __setup("uhash_entries=", set_uhash_entries);
2883 
2884 void __init udp_table_init(struct udp_table *table, const char *name)
2885 {
2886         unsigned int i;
2887 
2888         table->hash = alloc_large_system_hash(name,
2889                                               2 * sizeof(struct udp_hslot),
2890                                               uhash_entries,
2891                                               21, /* one slot per 2 MB */
2892                                               0,
2893                                               &table->log,
2894                                               &table->mask,
2895                                               UDP_HTABLE_SIZE_MIN,
2896                                               64 * 1024);
2897 
2898         table->hash2 = table->hash + (table->mask + 1);
2899         for (i = 0; i <= table->mask; i++) {
2900                 INIT_HLIST_HEAD(&table->hash[i].head);
2901                 table->hash[i].count = 0;
2902                 spin_lock_init(&table->hash[i].lock);
2903         }
2904         for (i = 0; i <= table->mask; i++) {
2905                 INIT_HLIST_HEAD(&table->hash2[i].head);
2906                 table->hash2[i].count = 0;
2907                 spin_lock_init(&table->hash2[i].lock);
2908         }
2909 }
2910 
2911 u32 udp_flow_hashrnd(void)
2912 {
2913         static u32 hashrnd __read_mostly;
2914 
2915         net_get_random_once(&hashrnd, sizeof(hashrnd));
2916 
2917         return hashrnd;
2918 }
2919 EXPORT_SYMBOL(udp_flow_hashrnd);
2920 
2921 static void __udp_sysctl_init(struct net *net)
2922 {
2923         net->ipv4.sysctl_udp_rmem_min = SK_MEM_QUANTUM;
2924         net->ipv4.sysctl_udp_wmem_min = SK_MEM_QUANTUM;
2925 
2926 #ifdef CONFIG_NET_L3_MASTER_DEV
2927         net->ipv4.sysctl_udp_l3mdev_accept = 0;
2928 #endif
2929 }
2930 
2931 static int __net_init udp_sysctl_init(struct net *net)
2932 {
2933         __udp_sysctl_init(net);
2934         return 0;
2935 }
2936 
2937 static struct pernet_operations __net_initdata udp_sysctl_ops = {
2938         .init   = udp_sysctl_init,
2939 };
2940 
2941 void __init udp_init(void)
2942 {
2943         unsigned long limit;
2944         unsigned int i;
2945 
2946         udp_table_init(&udp_table, "UDP");
2947         limit = nr_free_buffer_pages() / 8;
2948         limit = max(limit, 128UL);
2949         sysctl_udp_mem[0] = limit / 4 * 3;
2950         sysctl_udp_mem[1] = limit;
2951         sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2;
2952 
2953         __udp_sysctl_init(&init_net);
2954 
2955         /* 16 spinlocks per cpu */
2956         udp_busylocks_log = ilog2(nr_cpu_ids) + 4;
2957         udp_busylocks = kmalloc(sizeof(spinlock_t) << udp_busylocks_log,
2958                                 GFP_KERNEL);
2959         if (!udp_busylocks)
2960                 panic("UDP: failed to alloc udp_busylocks\n");
2961         for (i = 0; i < (1U << udp_busylocks_log); i++)
2962                 spin_lock_init(udp_busylocks + i);
2963 
2964         if (register_pernet_subsys(&udp_sysctl_ops))
2965                 panic("UDP: failed to init sysctl parameters.\n");
2966 }
2967 

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