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Linux/net/ipv4/udp.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  4  *              operating system.  INET is implemented using the  BSD Socket
  5  *              interface as the means of communication with the user level.
  6  *
  7  *              The User Datagram Protocol (UDP).
  8  *
  9  * Authors:     Ross Biro
 10  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 11  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 12  *              Alan Cox, <alan@lxorguk.ukuu.org.uk>
 13  *              Hirokazu Takahashi, <taka@valinux.co.jp>
 14  *
 15  * Fixes:
 16  *              Alan Cox        :       verify_area() calls
 17  *              Alan Cox        :       stopped close while in use off icmp
 18  *                                      messages. Not a fix but a botch that
 19  *                                      for udp at least is 'valid'.
 20  *              Alan Cox        :       Fixed icmp handling properly
 21  *              Alan Cox        :       Correct error for oversized datagrams
 22  *              Alan Cox        :       Tidied select() semantics.
 23  *              Alan Cox        :       udp_err() fixed properly, also now
 24  *                                      select and read wake correctly on errors
 25  *              Alan Cox        :       udp_send verify_area moved to avoid mem leak
 26  *              Alan Cox        :       UDP can count its memory
 27  *              Alan Cox        :       send to an unknown connection causes
 28  *                                      an ECONNREFUSED off the icmp, but
 29  *                                      does NOT close.
 30  *              Alan Cox        :       Switched to new sk_buff handlers. No more backlog!
 31  *              Alan Cox        :       Using generic datagram code. Even smaller and the PEEK
 32  *                                      bug no longer crashes it.
 33  *              Fred Van Kempen :       Net2e support for sk->broadcast.
 34  *              Alan Cox        :       Uses skb_free_datagram
 35  *              Alan Cox        :       Added get/set sockopt support.
 36  *              Alan Cox        :       Broadcasting without option set returns EACCES.
 37  *              Alan Cox        :       No wakeup calls. Instead we now use the callbacks.
 38  *              Alan Cox        :       Use ip_tos and ip_ttl
 39  *              Alan Cox        :       SNMP Mibs
 40  *              Alan Cox        :       MSG_DONTROUTE, and 0.0.0.0 support.
 41  *              Matt Dillon     :       UDP length checks.
 42  *              Alan Cox        :       Smarter af_inet used properly.
 43  *              Alan Cox        :       Use new kernel side addressing.
 44  *              Alan Cox        :       Incorrect return on truncated datagram receive.
 45  *      Arnt Gulbrandsen        :       New udp_send and stuff
 46  *              Alan Cox        :       Cache last socket
 47  *              Alan Cox        :       Route cache
 48  *              Jon Peatfield   :       Minor efficiency fix to sendto().
 49  *              Mike Shaver     :       RFC1122 checks.
 50  *              Alan Cox        :       Nonblocking error fix.
 51  *      Willy Konynenberg       :       Transparent proxying support.
 52  *              Mike McLagan    :       Routing by source
 53  *              David S. Miller :       New socket lookup architecture.
 54  *                                      Last socket cache retained as it
 55  *                                      does have a high hit rate.
 56  *              Olaf Kirch      :       Don't linearise iovec on sendmsg.
 57  *              Andi Kleen      :       Some cleanups, cache destination entry
 58  *                                      for connect.
 59  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
 60  *              Melvin Smith    :       Check msg_name not msg_namelen in sendto(),
 61  *                                      return ENOTCONN for unconnected sockets (POSIX)
 62  *              Janos Farkas    :       don't deliver multi/broadcasts to a different
 63  *                                      bound-to-device socket
 64  *      Hirokazu Takahashi      :       HW checksumming for outgoing UDP
 65  *                                      datagrams.
 66  *      Hirokazu Takahashi      :       sendfile() on UDP works now.
 67  *              Arnaldo C. Melo :       convert /proc/net/udp to seq_file
 68  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
 69  *      Alexey Kuznetsov:               allow both IPv4 and IPv6 sockets to bind
 70  *                                      a single port at the same time.
 71  *      Derek Atkins <derek@ihtfp.com>: Add Encapulation Support
 72  *      James Chapman           :       Add L2TP encapsulation type.
 73  */
 74 
 75 #define pr_fmt(fmt) "UDP: " fmt
 76 
 77 #include <linux/uaccess.h>
 78 #include <asm/ioctls.h>
 79 #include <linux/memblock.h>
 80 #include <linux/highmem.h>
 81 #include <linux/swap.h>
 82 #include <linux/types.h>
 83 #include <linux/fcntl.h>
 84 #include <linux/module.h>
 85 #include <linux/socket.h>
 86 #include <linux/sockios.h>
 87 #include <linux/igmp.h>
 88 #include <linux/inetdevice.h>
 89 #include <linux/in.h>
 90 #include <linux/errno.h>
 91 #include <linux/timer.h>
 92 #include <linux/mm.h>
 93 #include <linux/inet.h>
 94 #include <linux/netdevice.h>
 95 #include <linux/slab.h>
 96 #include <net/tcp_states.h>
 97 #include <linux/skbuff.h>
 98 #include <linux/proc_fs.h>
 99 #include <linux/seq_file.h>
100 #include <net/net_namespace.h>
101 #include <net/icmp.h>
102 #include <net/inet_hashtables.h>
103 #include <net/ip_tunnels.h>
104 #include <net/route.h>
105 #include <net/checksum.h>
106 #include <net/xfrm.h>
107 #include <trace/events/udp.h>
108 #include <linux/static_key.h>
109 #include <trace/events/skb.h>
110 #include <net/busy_poll.h>
111 #include "udp_impl.h"
112 #include <net/sock_reuseport.h>
113 #include <net/addrconf.h>
114 #include <net/udp_tunnel.h>
115 
116 struct udp_table udp_table __read_mostly;
117 EXPORT_SYMBOL(udp_table);
118 
119 long sysctl_udp_mem[3] __read_mostly;
120 EXPORT_SYMBOL(sysctl_udp_mem);
121 
122 atomic_long_t udp_memory_allocated;
123 EXPORT_SYMBOL(udp_memory_allocated);
124 
125 #define MAX_UDP_PORTS 65536
126 #define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN)
127 
128 static int udp_lib_lport_inuse(struct net *net, __u16 num,
129                                const struct udp_hslot *hslot,
130                                unsigned long *bitmap,
131                                struct sock *sk, unsigned int log)
132 {
133         struct sock *sk2;
134         kuid_t uid = sock_i_uid(sk);
135 
136         sk_for_each(sk2, &hslot->head) {
137                 if (net_eq(sock_net(sk2), net) &&
138                     sk2 != sk &&
139                     (bitmap || udp_sk(sk2)->udp_port_hash == num) &&
140                     (!sk2->sk_reuse || !sk->sk_reuse) &&
141                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
142                      sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
143                     inet_rcv_saddr_equal(sk, sk2, true)) {
144                         if (sk2->sk_reuseport && sk->sk_reuseport &&
145                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
146                             uid_eq(uid, sock_i_uid(sk2))) {
147                                 if (!bitmap)
148                                         return 0;
149                         } else {
150                                 if (!bitmap)
151                                         return 1;
152                                 __set_bit(udp_sk(sk2)->udp_port_hash >> log,
153                                           bitmap);
154                         }
155                 }
156         }
157         return 0;
158 }
159 
160 /*
161  * Note: we still hold spinlock of primary hash chain, so no other writer
162  * can insert/delete a socket with local_port == num
163  */
164 static int udp_lib_lport_inuse2(struct net *net, __u16 num,
165                                 struct udp_hslot *hslot2,
166                                 struct sock *sk)
167 {
168         struct sock *sk2;
169         kuid_t uid = sock_i_uid(sk);
170         int res = 0;
171 
172         spin_lock(&hslot2->lock);
173         udp_portaddr_for_each_entry(sk2, &hslot2->head) {
174                 if (net_eq(sock_net(sk2), net) &&
175                     sk2 != sk &&
176                     (udp_sk(sk2)->udp_port_hash == num) &&
177                     (!sk2->sk_reuse || !sk->sk_reuse) &&
178                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
179                      sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
180                     inet_rcv_saddr_equal(sk, sk2, true)) {
181                         if (sk2->sk_reuseport && sk->sk_reuseport &&
182                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
183                             uid_eq(uid, sock_i_uid(sk2))) {
184                                 res = 0;
185                         } else {
186                                 res = 1;
187                         }
188                         break;
189                 }
190         }
191         spin_unlock(&hslot2->lock);
192         return res;
193 }
194 
195 static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot)
196 {
197         struct net *net = sock_net(sk);
198         kuid_t uid = sock_i_uid(sk);
199         struct sock *sk2;
200 
201         sk_for_each(sk2, &hslot->head) {
202                 if (net_eq(sock_net(sk2), net) &&
203                     sk2 != sk &&
204                     sk2->sk_family == sk->sk_family &&
205                     ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
206                     (udp_sk(sk2)->udp_port_hash == udp_sk(sk)->udp_port_hash) &&
207                     (sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
208                     sk2->sk_reuseport && uid_eq(uid, sock_i_uid(sk2)) &&
209                     inet_rcv_saddr_equal(sk, sk2, false)) {
210                         return reuseport_add_sock(sk, sk2,
211                                                   inet_rcv_saddr_any(sk));
212                 }
213         }
214 
215         return reuseport_alloc(sk, inet_rcv_saddr_any(sk));
216 }
217 
218 /**
219  *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
220  *
221  *  @sk:          socket struct in question
222  *  @snum:        port number to look up
223  *  @hash2_nulladdr: AF-dependent hash value in secondary hash chains,
224  *                   with NULL address
225  */
226 int udp_lib_get_port(struct sock *sk, unsigned short snum,
227                      unsigned int hash2_nulladdr)
228 {
229         struct udp_hslot *hslot, *hslot2;
230         struct udp_table *udptable = sk->sk_prot->h.udp_table;
231         int    error = 1;
232         struct net *net = sock_net(sk);
233 
234         if (!snum) {
235                 int low, high, remaining;
236                 unsigned int rand;
237                 unsigned short first, last;
238                 DECLARE_BITMAP(bitmap, PORTS_PER_CHAIN);
239 
240                 inet_get_local_port_range(net, &low, &high);
241                 remaining = (high - low) + 1;
242 
243                 rand = prandom_u32();
244                 first = reciprocal_scale(rand, remaining) + low;
245                 /*
246                  * force rand to be an odd multiple of UDP_HTABLE_SIZE
247                  */
248                 rand = (rand | 1) * (udptable->mask + 1);
249                 last = first + udptable->mask + 1;
250                 do {
251                         hslot = udp_hashslot(udptable, net, first);
252                         bitmap_zero(bitmap, PORTS_PER_CHAIN);
253                         spin_lock_bh(&hslot->lock);
254                         udp_lib_lport_inuse(net, snum, hslot, bitmap, sk,
255                                             udptable->log);
256 
257                         snum = first;
258                         /*
259                          * Iterate on all possible values of snum for this hash.
260                          * Using steps of an odd multiple of UDP_HTABLE_SIZE
261                          * give us randomization and full range coverage.
262                          */
263                         do {
264                                 if (low <= snum && snum <= high &&
265                                     !test_bit(snum >> udptable->log, bitmap) &&
266                                     !inet_is_local_reserved_port(net, snum))
267                                         goto found;
268                                 snum += rand;
269                         } while (snum != first);
270                         spin_unlock_bh(&hslot->lock);
271                         cond_resched();
272                 } while (++first != last);
273                 goto fail;
274         } else {
275                 hslot = udp_hashslot(udptable, net, snum);
276                 spin_lock_bh(&hslot->lock);
277                 if (hslot->count > 10) {
278                         int exist;
279                         unsigned int slot2 = udp_sk(sk)->udp_portaddr_hash ^ snum;
280 
281                         slot2          &= udptable->mask;
282                         hash2_nulladdr &= udptable->mask;
283 
284                         hslot2 = udp_hashslot2(udptable, slot2);
285                         if (hslot->count < hslot2->count)
286                                 goto scan_primary_hash;
287 
288                         exist = udp_lib_lport_inuse2(net, snum, hslot2, sk);
289                         if (!exist && (hash2_nulladdr != slot2)) {
290                                 hslot2 = udp_hashslot2(udptable, hash2_nulladdr);
291                                 exist = udp_lib_lport_inuse2(net, snum, hslot2,
292                                                              sk);
293                         }
294                         if (exist)
295                                 goto fail_unlock;
296                         else
297                                 goto found;
298                 }
299 scan_primary_hash:
300                 if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, 0))
301                         goto fail_unlock;
302         }
303 found:
304         inet_sk(sk)->inet_num = snum;
305         udp_sk(sk)->udp_port_hash = snum;
306         udp_sk(sk)->udp_portaddr_hash ^= snum;
307         if (sk_unhashed(sk)) {
308                 if (sk->sk_reuseport &&
309                     udp_reuseport_add_sock(sk, hslot)) {
310                         inet_sk(sk)->inet_num = 0;
311                         udp_sk(sk)->udp_port_hash = 0;
312                         udp_sk(sk)->udp_portaddr_hash ^= snum;
313                         goto fail_unlock;
314                 }
315 
316                 sk_add_node_rcu(sk, &hslot->head);
317                 hslot->count++;
318                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
319 
320                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
321                 spin_lock(&hslot2->lock);
322                 if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
323                     sk->sk_family == AF_INET6)
324                         hlist_add_tail_rcu(&udp_sk(sk)->udp_portaddr_node,
325                                            &hslot2->head);
326                 else
327                         hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
328                                            &hslot2->head);
329                 hslot2->count++;
330                 spin_unlock(&hslot2->lock);
331         }
332         sock_set_flag(sk, SOCK_RCU_FREE);
333         error = 0;
334 fail_unlock:
335         spin_unlock_bh(&hslot->lock);
336 fail:
337         return error;
338 }
339 EXPORT_SYMBOL(udp_lib_get_port);
340 
341 int udp_v4_get_port(struct sock *sk, unsigned short snum)
342 {
343         unsigned int hash2_nulladdr =
344                 ipv4_portaddr_hash(sock_net(sk), htonl(INADDR_ANY), snum);
345         unsigned int hash2_partial =
346                 ipv4_portaddr_hash(sock_net(sk), inet_sk(sk)->inet_rcv_saddr, 0);
347 
348         /* precompute partial secondary hash */
349         udp_sk(sk)->udp_portaddr_hash = hash2_partial;
350         return udp_lib_get_port(sk, snum, hash2_nulladdr);
351 }
352 
353 static int compute_score(struct sock *sk, struct net *net,
354                          __be32 saddr, __be16 sport,
355                          __be32 daddr, unsigned short hnum,
356                          int dif, int sdif)
357 {
358         int score;
359         struct inet_sock *inet;
360         bool dev_match;
361 
362         if (!net_eq(sock_net(sk), net) ||
363             udp_sk(sk)->udp_port_hash != hnum ||
364             ipv6_only_sock(sk))
365                 return -1;
366 
367         if (sk->sk_rcv_saddr != daddr)
368                 return -1;
369 
370         score = (sk->sk_family == PF_INET) ? 2 : 1;
371 
372         inet = inet_sk(sk);
373         if (inet->inet_daddr) {
374                 if (inet->inet_daddr != saddr)
375                         return -1;
376                 score += 4;
377         }
378 
379         if (inet->inet_dport) {
380                 if (inet->inet_dport != sport)
381                         return -1;
382                 score += 4;
383         }
384 
385         dev_match = udp_sk_bound_dev_eq(net, sk->sk_bound_dev_if,
386                                         dif, sdif);
387         if (!dev_match)
388                 return -1;
389         score += 4;
390 
391         if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
392                 score++;
393         return score;
394 }
395 
396 static u32 udp_ehashfn(const struct net *net, const __be32 laddr,
397                        const __u16 lport, const __be32 faddr,
398                        const __be16 fport)
399 {
400         static u32 udp_ehash_secret __read_mostly;
401 
402         net_get_random_once(&udp_ehash_secret, sizeof(udp_ehash_secret));
403 
404         return __inet_ehashfn(laddr, lport, faddr, fport,
405                               udp_ehash_secret + net_hash_mix(net));
406 }
407 
408 /* called with rcu_read_lock() */
409 static struct sock *udp4_lib_lookup2(struct net *net,
410                                      __be32 saddr, __be16 sport,
411                                      __be32 daddr, unsigned int hnum,
412                                      int dif, int sdif,
413                                      struct udp_hslot *hslot2,
414                                      struct sk_buff *skb)
415 {
416         struct sock *sk, *result;
417         int score, badness;
418         u32 hash = 0;
419 
420         result = NULL;
421         badness = 0;
422         udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
423                 score = compute_score(sk, net, saddr, sport,
424                                       daddr, hnum, dif, sdif);
425                 if (score > badness) {
426                         if (sk->sk_reuseport &&
427                             sk->sk_state != TCP_ESTABLISHED) {
428                                 hash = udp_ehashfn(net, daddr, hnum,
429                                                    saddr, sport);
430                                 result = reuseport_select_sock(sk, hash, skb,
431                                                         sizeof(struct udphdr));
432                                 if (result && !reuseport_has_conns(sk, false))
433                                         return result;
434                         }
435                         badness = score;
436                         result = sk;
437                 }
438         }
439         return result;
440 }
441 
442 /* UDP is nearly always wildcards out the wazoo, it makes no sense to try
443  * harder than this. -DaveM
444  */
445 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
446                 __be16 sport, __be32 daddr, __be16 dport, int dif,
447                 int sdif, struct udp_table *udptable, struct sk_buff *skb)
448 {
449         struct sock *result;
450         unsigned short hnum = ntohs(dport);
451         unsigned int hash2, slot2;
452         struct udp_hslot *hslot2;
453 
454         hash2 = ipv4_portaddr_hash(net, daddr, hnum);
455         slot2 = hash2 & udptable->mask;
456         hslot2 = &udptable->hash2[slot2];
457 
458         result = udp4_lib_lookup2(net, saddr, sport,
459                                   daddr, hnum, dif, sdif,
460                                   hslot2, skb);
461         if (!result) {
462                 hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
463                 slot2 = hash2 & udptable->mask;
464                 hslot2 = &udptable->hash2[slot2];
465 
466                 result = udp4_lib_lookup2(net, saddr, sport,
467                                           htonl(INADDR_ANY), hnum, dif, sdif,
468                                           hslot2, skb);
469         }
470         if (IS_ERR(result))
471                 return NULL;
472         return result;
473 }
474 EXPORT_SYMBOL_GPL(__udp4_lib_lookup);
475 
476 static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
477                                                  __be16 sport, __be16 dport,
478                                                  struct udp_table *udptable)
479 {
480         const struct iphdr *iph = ip_hdr(skb);
481 
482         return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
483                                  iph->daddr, dport, inet_iif(skb),
484                                  inet_sdif(skb), udptable, skb);
485 }
486 
487 struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
488                                  __be16 sport, __be16 dport)
489 {
490         const struct iphdr *iph = ip_hdr(skb);
491 
492         return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
493                                  iph->daddr, dport, inet_iif(skb),
494                                  inet_sdif(skb), &udp_table, NULL);
495 }
496 EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
497 
498 /* Must be called under rcu_read_lock().
499  * Does increment socket refcount.
500  */
501 #if IS_ENABLED(CONFIG_NF_TPROXY_IPV4) || IS_ENABLED(CONFIG_NF_SOCKET_IPV4)
502 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
503                              __be32 daddr, __be16 dport, int dif)
504 {
505         struct sock *sk;
506 
507         sk = __udp4_lib_lookup(net, saddr, sport, daddr, dport,
508                                dif, 0, &udp_table, NULL);
509         if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
510                 sk = NULL;
511         return sk;
512 }
513 EXPORT_SYMBOL_GPL(udp4_lib_lookup);
514 #endif
515 
516 static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk,
517                                        __be16 loc_port, __be32 loc_addr,
518                                        __be16 rmt_port, __be32 rmt_addr,
519                                        int dif, int sdif, unsigned short hnum)
520 {
521         struct inet_sock *inet = inet_sk(sk);
522 
523         if (!net_eq(sock_net(sk), net) ||
524             udp_sk(sk)->udp_port_hash != hnum ||
525             (inet->inet_daddr && inet->inet_daddr != rmt_addr) ||
526             (inet->inet_dport != rmt_port && inet->inet_dport) ||
527             (inet->inet_rcv_saddr && inet->inet_rcv_saddr != loc_addr) ||
528             ipv6_only_sock(sk) ||
529             !udp_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
530                 return false;
531         if (!ip_mc_sf_allow(sk, loc_addr, rmt_addr, dif, sdif))
532                 return false;
533         return true;
534 }
535 
536 DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
537 void udp_encap_enable(void)
538 {
539         static_branch_inc(&udp_encap_needed_key);
540 }
541 EXPORT_SYMBOL(udp_encap_enable);
542 
543 /* Handler for tunnels with arbitrary destination ports: no socket lookup, go
544  * through error handlers in encapsulations looking for a match.
545  */
546 static int __udp4_lib_err_encap_no_sk(struct sk_buff *skb, u32 info)
547 {
548         int i;
549 
550         for (i = 0; i < MAX_IPTUN_ENCAP_OPS; i++) {
551                 int (*handler)(struct sk_buff *skb, u32 info);
552                 const struct ip_tunnel_encap_ops *encap;
553 
554                 encap = rcu_dereference(iptun_encaps[i]);
555                 if (!encap)
556                         continue;
557                 handler = encap->err_handler;
558                 if (handler && !handler(skb, info))
559                         return 0;
560         }
561 
562         return -ENOENT;
563 }
564 
565 /* Try to match ICMP errors to UDP tunnels by looking up a socket without
566  * reversing source and destination port: this will match tunnels that force the
567  * same destination port on both endpoints (e.g. VXLAN, GENEVE). Note that
568  * lwtunnels might actually break this assumption by being configured with
569  * different destination ports on endpoints, in this case we won't be able to
570  * trace ICMP messages back to them.
571  *
572  * If this doesn't match any socket, probe tunnels with arbitrary destination
573  * ports (e.g. FoU, GUE): there, the receiving socket is useless, as the port
574  * we've sent packets to won't necessarily match the local destination port.
575  *
576  * Then ask the tunnel implementation to match the error against a valid
577  * association.
578  *
579  * Return an error if we can't find a match, the socket if we need further
580  * processing, zero otherwise.
581  */
582 static struct sock *__udp4_lib_err_encap(struct net *net,
583                                          const struct iphdr *iph,
584                                          struct udphdr *uh,
585                                          struct udp_table *udptable,
586                                          struct sk_buff *skb, u32 info)
587 {
588         int network_offset, transport_offset;
589         struct sock *sk;
590 
591         network_offset = skb_network_offset(skb);
592         transport_offset = skb_transport_offset(skb);
593 
594         /* Network header needs to point to the outer IPv4 header inside ICMP */
595         skb_reset_network_header(skb);
596 
597         /* Transport header needs to point to the UDP header */
598         skb_set_transport_header(skb, iph->ihl << 2);
599 
600         sk = __udp4_lib_lookup(net, iph->daddr, uh->source,
601                                iph->saddr, uh->dest, skb->dev->ifindex, 0,
602                                udptable, NULL);
603         if (sk) {
604                 int (*lookup)(struct sock *sk, struct sk_buff *skb);
605                 struct udp_sock *up = udp_sk(sk);
606 
607                 lookup = READ_ONCE(up->encap_err_lookup);
608                 if (!lookup || lookup(sk, skb))
609                         sk = NULL;
610         }
611 
612         if (!sk)
613                 sk = ERR_PTR(__udp4_lib_err_encap_no_sk(skb, info));
614 
615         skb_set_transport_header(skb, transport_offset);
616         skb_set_network_header(skb, network_offset);
617 
618         return sk;
619 }
620 
621 /*
622  * This routine is called by the ICMP module when it gets some
623  * sort of error condition.  If err < 0 then the socket should
624  * be closed and the error returned to the user.  If err > 0
625  * it's just the icmp type << 8 | icmp code.
626  * Header points to the ip header of the error packet. We move
627  * on past this. Then (as it used to claim before adjustment)
628  * header points to the first 8 bytes of the udp header.  We need
629  * to find the appropriate port.
630  */
631 
632 int __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
633 {
634         struct inet_sock *inet;
635         const struct iphdr *iph = (const struct iphdr *)skb->data;
636         struct udphdr *uh = (struct udphdr *)(skb->data+(iph->ihl<<2));
637         const int type = icmp_hdr(skb)->type;
638         const int code = icmp_hdr(skb)->code;
639         bool tunnel = false;
640         struct sock *sk;
641         int harderr;
642         int err;
643         struct net *net = dev_net(skb->dev);
644 
645         sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
646                                iph->saddr, uh->source, skb->dev->ifindex,
647                                inet_sdif(skb), udptable, NULL);
648         if (!sk) {
649                 /* No socket for error: try tunnels before discarding */
650                 sk = ERR_PTR(-ENOENT);
651                 if (static_branch_unlikely(&udp_encap_needed_key)) {
652                         sk = __udp4_lib_err_encap(net, iph, uh, udptable, skb,
653                                                   info);
654                         if (!sk)
655                                 return 0;
656                 }
657 
658                 if (IS_ERR(sk)) {
659                         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
660                         return PTR_ERR(sk);
661                 }
662 
663                 tunnel = true;
664         }
665 
666         err = 0;
667         harderr = 0;
668         inet = inet_sk(sk);
669 
670         switch (type) {
671         default:
672         case ICMP_TIME_EXCEEDED:
673                 err = EHOSTUNREACH;
674                 break;
675         case ICMP_SOURCE_QUENCH:
676                 goto out;
677         case ICMP_PARAMETERPROB:
678                 err = EPROTO;
679                 harderr = 1;
680                 break;
681         case ICMP_DEST_UNREACH:
682                 if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
683                         ipv4_sk_update_pmtu(skb, sk, info);
684                         if (inet->pmtudisc != IP_PMTUDISC_DONT) {
685                                 err = EMSGSIZE;
686                                 harderr = 1;
687                                 break;
688                         }
689                         goto out;
690                 }
691                 err = EHOSTUNREACH;
692                 if (code <= NR_ICMP_UNREACH) {
693                         harderr = icmp_err_convert[code].fatal;
694                         err = icmp_err_convert[code].errno;
695                 }
696                 break;
697         case ICMP_REDIRECT:
698                 ipv4_sk_redirect(skb, sk);
699                 goto out;
700         }
701 
702         /*
703          *      RFC1122: OK.  Passes ICMP errors back to application, as per
704          *      4.1.3.3.
705          */
706         if (tunnel) {
707                 /* ...not for tunnels though: we don't have a sending socket */
708                 goto out;
709         }
710         if (!inet->recverr) {
711                 if (!harderr || sk->sk_state != TCP_ESTABLISHED)
712                         goto out;
713         } else
714                 ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1));
715 
716         sk->sk_err = err;
717         sk->sk_error_report(sk);
718 out:
719         return 0;
720 }
721 
722 int udp_err(struct sk_buff *skb, u32 info)
723 {
724         return __udp4_lib_err(skb, info, &udp_table);
725 }
726 
727 /*
728  * Throw away all pending data and cancel the corking. Socket is locked.
729  */
730 void udp_flush_pending_frames(struct sock *sk)
731 {
732         struct udp_sock *up = udp_sk(sk);
733 
734         if (up->pending) {
735                 up->len = 0;
736                 up->pending = 0;
737                 ip_flush_pending_frames(sk);
738         }
739 }
740 EXPORT_SYMBOL(udp_flush_pending_frames);
741 
742 /**
743  *      udp4_hwcsum  -  handle outgoing HW checksumming
744  *      @skb:   sk_buff containing the filled-in UDP header
745  *              (checksum field must be zeroed out)
746  *      @src:   source IP address
747  *      @dst:   destination IP address
748  */
749 void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst)
750 {
751         struct udphdr *uh = udp_hdr(skb);
752         int offset = skb_transport_offset(skb);
753         int len = skb->len - offset;
754         int hlen = len;
755         __wsum csum = 0;
756 
757         if (!skb_has_frag_list(skb)) {
758                 /*
759                  * Only one fragment on the socket.
760                  */
761                 skb->csum_start = skb_transport_header(skb) - skb->head;
762                 skb->csum_offset = offsetof(struct udphdr, check);
763                 uh->check = ~csum_tcpudp_magic(src, dst, len,
764                                                IPPROTO_UDP, 0);
765         } else {
766                 struct sk_buff *frags;
767 
768                 /*
769                  * HW-checksum won't work as there are two or more
770                  * fragments on the socket so that all csums of sk_buffs
771                  * should be together
772                  */
773                 skb_walk_frags(skb, frags) {
774                         csum = csum_add(csum, frags->csum);
775                         hlen -= frags->len;
776                 }
777 
778                 csum = skb_checksum(skb, offset, hlen, csum);
779                 skb->ip_summed = CHECKSUM_NONE;
780 
781                 uh->check = csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum);
782                 if (uh->check == 0)
783                         uh->check = CSUM_MANGLED_0;
784         }
785 }
786 EXPORT_SYMBOL_GPL(udp4_hwcsum);
787 
788 /* Function to set UDP checksum for an IPv4 UDP packet. This is intended
789  * for the simple case like when setting the checksum for a UDP tunnel.
790  */
791 void udp_set_csum(bool nocheck, struct sk_buff *skb,
792                   __be32 saddr, __be32 daddr, int len)
793 {
794         struct udphdr *uh = udp_hdr(skb);
795 
796         if (nocheck) {
797                 uh->check = 0;
798         } else if (skb_is_gso(skb)) {
799                 uh->check = ~udp_v4_check(len, saddr, daddr, 0);
800         } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
801                 uh->check = 0;
802                 uh->check = udp_v4_check(len, saddr, daddr, lco_csum(skb));
803                 if (uh->check == 0)
804                         uh->check = CSUM_MANGLED_0;
805         } else {
806                 skb->ip_summed = CHECKSUM_PARTIAL;
807                 skb->csum_start = skb_transport_header(skb) - skb->head;
808                 skb->csum_offset = offsetof(struct udphdr, check);
809                 uh->check = ~udp_v4_check(len, saddr, daddr, 0);
810         }
811 }
812 EXPORT_SYMBOL(udp_set_csum);
813 
814 static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
815                         struct inet_cork *cork)
816 {
817         struct sock *sk = skb->sk;
818         struct inet_sock *inet = inet_sk(sk);
819         struct udphdr *uh;
820         int err = 0;
821         int is_udplite = IS_UDPLITE(sk);
822         int offset = skb_transport_offset(skb);
823         int len = skb->len - offset;
824         int datalen = len - sizeof(*uh);
825         __wsum csum = 0;
826 
827         /*
828          * Create a UDP header
829          */
830         uh = udp_hdr(skb);
831         uh->source = inet->inet_sport;
832         uh->dest = fl4->fl4_dport;
833         uh->len = htons(len);
834         uh->check = 0;
835 
836         if (cork->gso_size) {
837                 const int hlen = skb_network_header_len(skb) +
838                                  sizeof(struct udphdr);
839 
840                 if (hlen + cork->gso_size > cork->fragsize) {
841                         kfree_skb(skb);
842                         return -EINVAL;
843                 }
844                 if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
845                         kfree_skb(skb);
846                         return -EINVAL;
847                 }
848                 if (sk->sk_no_check_tx) {
849                         kfree_skb(skb);
850                         return -EINVAL;
851                 }
852                 if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
853                     dst_xfrm(skb_dst(skb))) {
854                         kfree_skb(skb);
855                         return -EIO;
856                 }
857 
858                 if (datalen > cork->gso_size) {
859                         skb_shinfo(skb)->gso_size = cork->gso_size;
860                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP_L4;
861                         skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(datalen,
862                                                                  cork->gso_size);
863                 }
864                 goto csum_partial;
865         }
866 
867         if (is_udplite)                                  /*     UDP-Lite      */
868                 csum = udplite_csum(skb);
869 
870         else if (sk->sk_no_check_tx) {                   /* UDP csum off */
871 
872                 skb->ip_summed = CHECKSUM_NONE;
873                 goto send;
874 
875         } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
876 csum_partial:
877 
878                 udp4_hwcsum(skb, fl4->saddr, fl4->daddr);
879                 goto send;
880 
881         } else
882                 csum = udp_csum(skb);
883 
884         /* add protocol-dependent pseudo-header */
885         uh->check = csum_tcpudp_magic(fl4->saddr, fl4->daddr, len,
886                                       sk->sk_protocol, csum);
887         if (uh->check == 0)
888                 uh->check = CSUM_MANGLED_0;
889 
890 send:
891         err = ip_send_skb(sock_net(sk), skb);
892         if (err) {
893                 if (err == -ENOBUFS && !inet->recverr) {
894                         UDP_INC_STATS(sock_net(sk),
895                                       UDP_MIB_SNDBUFERRORS, is_udplite);
896                         err = 0;
897                 }
898         } else
899                 UDP_INC_STATS(sock_net(sk),
900                               UDP_MIB_OUTDATAGRAMS, is_udplite);
901         return err;
902 }
903 
904 /*
905  * Push out all pending data as one UDP datagram. Socket is locked.
906  */
907 int udp_push_pending_frames(struct sock *sk)
908 {
909         struct udp_sock  *up = udp_sk(sk);
910         struct inet_sock *inet = inet_sk(sk);
911         struct flowi4 *fl4 = &inet->cork.fl.u.ip4;
912         struct sk_buff *skb;
913         int err = 0;
914 
915         skb = ip_finish_skb(sk, fl4);
916         if (!skb)
917                 goto out;
918 
919         err = udp_send_skb(skb, fl4, &inet->cork.base);
920 
921 out:
922         up->len = 0;
923         up->pending = 0;
924         return err;
925 }
926 EXPORT_SYMBOL(udp_push_pending_frames);
927 
928 static int __udp_cmsg_send(struct cmsghdr *cmsg, u16 *gso_size)
929 {
930         switch (cmsg->cmsg_type) {
931         case UDP_SEGMENT:
932                 if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u16)))
933                         return -EINVAL;
934                 *gso_size = *(__u16 *)CMSG_DATA(cmsg);
935                 return 0;
936         default:
937                 return -EINVAL;
938         }
939 }
940 
941 int udp_cmsg_send(struct sock *sk, struct msghdr *msg, u16 *gso_size)
942 {
943         struct cmsghdr *cmsg;
944         bool need_ip = false;
945         int err;
946 
947         for_each_cmsghdr(cmsg, msg) {
948                 if (!CMSG_OK(msg, cmsg))
949                         return -EINVAL;
950 
951                 if (cmsg->cmsg_level != SOL_UDP) {
952                         need_ip = true;
953                         continue;
954                 }
955 
956                 err = __udp_cmsg_send(cmsg, gso_size);
957                 if (err)
958                         return err;
959         }
960 
961         return need_ip;
962 }
963 EXPORT_SYMBOL_GPL(udp_cmsg_send);
964 
965 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
966 {
967         struct inet_sock *inet = inet_sk(sk);
968         struct udp_sock *up = udp_sk(sk);
969         DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
970         struct flowi4 fl4_stack;
971         struct flowi4 *fl4;
972         int ulen = len;
973         struct ipcm_cookie ipc;
974         struct rtable *rt = NULL;
975         int free = 0;
976         int connected = 0;
977         __be32 daddr, faddr, saddr;
978         __be16 dport;
979         u8  tos;
980         int err, is_udplite = IS_UDPLITE(sk);
981         int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
982         int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
983         struct sk_buff *skb;
984         struct ip_options_data opt_copy;
985 
986         if (len > 0xFFFF)
987                 return -EMSGSIZE;
988 
989         /*
990          *      Check the flags.
991          */
992 
993         if (msg->msg_flags & MSG_OOB) /* Mirror BSD error message compatibility */
994                 return -EOPNOTSUPP;
995 
996         getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag;
997 
998         fl4 = &inet->cork.fl.u.ip4;
999         if (up->pending) {
1000                 /*
1001                  * There are pending frames.
1002                  * The socket lock must be held while it's corked.
1003                  */
1004                 lock_sock(sk);
1005                 if (likely(up->pending)) {
1006                         if (unlikely(up->pending != AF_INET)) {
1007                                 release_sock(sk);
1008                                 return -EINVAL;
1009                         }
1010                         goto do_append_data;
1011                 }
1012                 release_sock(sk);
1013         }
1014         ulen += sizeof(struct udphdr);
1015 
1016         /*
1017          *      Get and verify the address.
1018          */
1019         if (usin) {
1020                 if (msg->msg_namelen < sizeof(*usin))
1021                         return -EINVAL;
1022                 if (usin->sin_family != AF_INET) {
1023                         if (usin->sin_family != AF_UNSPEC)
1024                                 return -EAFNOSUPPORT;
1025                 }
1026 
1027                 daddr = usin->sin_addr.s_addr;
1028                 dport = usin->sin_port;
1029                 if (dport == 0)
1030                         return -EINVAL;
1031         } else {
1032                 if (sk->sk_state != TCP_ESTABLISHED)
1033                         return -EDESTADDRREQ;
1034                 daddr = inet->inet_daddr;
1035                 dport = inet->inet_dport;
1036                 /* Open fast path for connected socket.
1037                    Route will not be used, if at least one option is set.
1038                  */
1039                 connected = 1;
1040         }
1041 
1042         ipcm_init_sk(&ipc, inet);
1043         ipc.gso_size = up->gso_size;
1044 
1045         if (msg->msg_controllen) {
1046                 err = udp_cmsg_send(sk, msg, &ipc.gso_size);
1047                 if (err > 0)
1048                         err = ip_cmsg_send(sk, msg, &ipc,
1049                                            sk->sk_family == AF_INET6);
1050                 if (unlikely(err < 0)) {
1051                         kfree(ipc.opt);
1052                         return err;
1053                 }
1054                 if (ipc.opt)
1055                         free = 1;
1056                 connected = 0;
1057         }
1058         if (!ipc.opt) {
1059                 struct ip_options_rcu *inet_opt;
1060 
1061                 rcu_read_lock();
1062                 inet_opt = rcu_dereference(inet->inet_opt);
1063                 if (inet_opt) {
1064                         memcpy(&opt_copy, inet_opt,
1065                                sizeof(*inet_opt) + inet_opt->opt.optlen);
1066                         ipc.opt = &opt_copy.opt;
1067                 }
1068                 rcu_read_unlock();
1069         }
1070 
1071         if (cgroup_bpf_enabled && !connected) {
1072                 err = BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk,
1073                                             (struct sockaddr *)usin, &ipc.addr);
1074                 if (err)
1075                         goto out_free;
1076                 if (usin) {
1077                         if (usin->sin_port == 0) {
1078                                 /* BPF program set invalid port. Reject it. */
1079                                 err = -EINVAL;
1080                                 goto out_free;
1081                         }
1082                         daddr = usin->sin_addr.s_addr;
1083                         dport = usin->sin_port;
1084                 }
1085         }
1086 
1087         saddr = ipc.addr;
1088         ipc.addr = faddr = daddr;
1089 
1090         if (ipc.opt && ipc.opt->opt.srr) {
1091                 if (!daddr) {
1092                         err = -EINVAL;
1093                         goto out_free;
1094                 }
1095                 faddr = ipc.opt->opt.faddr;
1096                 connected = 0;
1097         }
1098         tos = get_rttos(&ipc, inet);
1099         if (sock_flag(sk, SOCK_LOCALROUTE) ||
1100             (msg->msg_flags & MSG_DONTROUTE) ||
1101             (ipc.opt && ipc.opt->opt.is_strictroute)) {
1102                 tos |= RTO_ONLINK;
1103                 connected = 0;
1104         }
1105 
1106         if (ipv4_is_multicast(daddr)) {
1107                 if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
1108                         ipc.oif = inet->mc_index;
1109                 if (!saddr)
1110                         saddr = inet->mc_addr;
1111                 connected = 0;
1112         } else if (!ipc.oif) {
1113                 ipc.oif = inet->uc_index;
1114         } else if (ipv4_is_lbcast(daddr) && inet->uc_index) {
1115                 /* oif is set, packet is to local broadcast and
1116                  * and uc_index is set. oif is most likely set
1117                  * by sk_bound_dev_if. If uc_index != oif check if the
1118                  * oif is an L3 master and uc_index is an L3 slave.
1119                  * If so, we want to allow the send using the uc_index.
1120                  */
1121                 if (ipc.oif != inet->uc_index &&
1122                     ipc.oif == l3mdev_master_ifindex_by_index(sock_net(sk),
1123                                                               inet->uc_index)) {
1124                         ipc.oif = inet->uc_index;
1125                 }
1126         }
1127 
1128         if (connected)
1129                 rt = (struct rtable *)sk_dst_check(sk, 0);
1130 
1131         if (!rt) {
1132                 struct net *net = sock_net(sk);
1133                 __u8 flow_flags = inet_sk_flowi_flags(sk);
1134 
1135                 fl4 = &fl4_stack;
1136 
1137                 flowi4_init_output(fl4, ipc.oif, ipc.sockc.mark, tos,
1138                                    RT_SCOPE_UNIVERSE, sk->sk_protocol,
1139                                    flow_flags,
1140                                    faddr, saddr, dport, inet->inet_sport,
1141                                    sk->sk_uid);
1142 
1143                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
1144                 rt = ip_route_output_flow(net, fl4, sk);
1145                 if (IS_ERR(rt)) {
1146                         err = PTR_ERR(rt);
1147                         rt = NULL;
1148                         if (err == -ENETUNREACH)
1149                                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
1150                         goto out;
1151                 }
1152 
1153                 err = -EACCES;
1154                 if ((rt->rt_flags & RTCF_BROADCAST) &&
1155                     !sock_flag(sk, SOCK_BROADCAST))
1156                         goto out;
1157                 if (connected)
1158                         sk_dst_set(sk, dst_clone(&rt->dst));
1159         }
1160 
1161         if (msg->msg_flags&MSG_CONFIRM)
1162                 goto do_confirm;
1163 back_from_confirm:
1164 
1165         saddr = fl4->saddr;
1166         if (!ipc.addr)
1167                 daddr = ipc.addr = fl4->daddr;
1168 
1169         /* Lockless fast path for the non-corking case. */
1170         if (!corkreq) {
1171                 struct inet_cork cork;
1172 
1173                 skb = ip_make_skb(sk, fl4, getfrag, msg, ulen,
1174                                   sizeof(struct udphdr), &ipc, &rt,
1175                                   &cork, msg->msg_flags);
1176                 err = PTR_ERR(skb);
1177                 if (!IS_ERR_OR_NULL(skb))
1178                         err = udp_send_skb(skb, fl4, &cork);
1179                 goto out;
1180         }
1181 
1182         lock_sock(sk);
1183         if (unlikely(up->pending)) {
1184                 /* The socket is already corked while preparing it. */
1185                 /* ... which is an evident application bug. --ANK */
1186                 release_sock(sk);
1187 
1188                 net_dbg_ratelimited("socket already corked\n");
1189                 err = -EINVAL;
1190                 goto out;
1191         }
1192         /*
1193          *      Now cork the socket to pend data.
1194          */
1195         fl4 = &inet->cork.fl.u.ip4;
1196         fl4->daddr = daddr;
1197         fl4->saddr = saddr;
1198         fl4->fl4_dport = dport;
1199         fl4->fl4_sport = inet->inet_sport;
1200         up->pending = AF_INET;
1201 
1202 do_append_data:
1203         up->len += ulen;
1204         err = ip_append_data(sk, fl4, getfrag, msg, ulen,
1205                              sizeof(struct udphdr), &ipc, &rt,
1206                              corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
1207         if (err)
1208                 udp_flush_pending_frames(sk);
1209         else if (!corkreq)
1210                 err = udp_push_pending_frames(sk);
1211         else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
1212                 up->pending = 0;
1213         release_sock(sk);
1214 
1215 out:
1216         ip_rt_put(rt);
1217 out_free:
1218         if (free)
1219                 kfree(ipc.opt);
1220         if (!err)
1221                 return len;
1222         /*
1223          * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
1224          * ENOBUFS might not be good (it's not tunable per se), but otherwise
1225          * we don't have a good statistic (IpOutDiscards but it can be too many
1226          * things).  We could add another new stat but at least for now that
1227          * seems like overkill.
1228          */
1229         if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
1230                 UDP_INC_STATS(sock_net(sk),
1231                               UDP_MIB_SNDBUFERRORS, is_udplite);
1232         }
1233         return err;
1234 
1235 do_confirm:
1236         if (msg->msg_flags & MSG_PROBE)
1237                 dst_confirm_neigh(&rt->dst, &fl4->daddr);
1238         if (!(msg->msg_flags&MSG_PROBE) || len)
1239                 goto back_from_confirm;
1240         err = 0;
1241         goto out;
1242 }
1243 EXPORT_SYMBOL(udp_sendmsg);
1244 
1245 int udp_sendpage(struct sock *sk, struct page *page, int offset,
1246                  size_t size, int flags)
1247 {
1248         struct inet_sock *inet = inet_sk(sk);
1249         struct udp_sock *up = udp_sk(sk);
1250         int ret;
1251 
1252         if (flags & MSG_SENDPAGE_NOTLAST)
1253                 flags |= MSG_MORE;
1254 
1255         if (!up->pending) {
1256                 struct msghdr msg = {   .msg_flags = flags|MSG_MORE };
1257 
1258                 /* Call udp_sendmsg to specify destination address which
1259                  * sendpage interface can't pass.
1260                  * This will succeed only when the socket is connected.
1261                  */
1262                 ret = udp_sendmsg(sk, &msg, 0);
1263                 if (ret < 0)
1264                         return ret;
1265         }
1266 
1267         lock_sock(sk);
1268 
1269         if (unlikely(!up->pending)) {
1270                 release_sock(sk);
1271 
1272                 net_dbg_ratelimited("cork failed\n");
1273                 return -EINVAL;
1274         }
1275 
1276         ret = ip_append_page(sk, &inet->cork.fl.u.ip4,
1277                              page, offset, size, flags);
1278         if (ret == -EOPNOTSUPP) {
1279                 release_sock(sk);
1280                 return sock_no_sendpage(sk->sk_socket, page, offset,
1281                                         size, flags);
1282         }
1283         if (ret < 0) {
1284                 udp_flush_pending_frames(sk);
1285                 goto out;
1286         }
1287 
1288         up->len += size;
1289         if (!(up->corkflag || (flags&MSG_MORE)))
1290                 ret = udp_push_pending_frames(sk);
1291         if (!ret)
1292                 ret = size;
1293 out:
1294         release_sock(sk);
1295         return ret;
1296 }
1297 
1298 #define UDP_SKB_IS_STATELESS 0x80000000
1299 
1300 /* all head states (dst, sk, nf conntrack) except skb extensions are
1301  * cleared by udp_rcv().
1302  *
1303  * We need to preserve secpath, if present, to eventually process
1304  * IP_CMSG_PASSSEC at recvmsg() time.
1305  *
1306  * Other extensions can be cleared.
1307  */
1308 static bool udp_try_make_stateless(struct sk_buff *skb)
1309 {
1310         if (!skb_has_extensions(skb))
1311                 return true;
1312 
1313         if (!secpath_exists(skb)) {
1314                 skb_ext_reset(skb);
1315                 return true;
1316         }
1317 
1318         return false;
1319 }
1320 
1321 static void udp_set_dev_scratch(struct sk_buff *skb)
1322 {
1323         struct udp_dev_scratch *scratch = udp_skb_scratch(skb);
1324 
1325         BUILD_BUG_ON(sizeof(struct udp_dev_scratch) > sizeof(long));
1326         scratch->_tsize_state = skb->truesize;
1327 #if BITS_PER_LONG == 64
1328         scratch->len = skb->len;
1329         scratch->csum_unnecessary = !!skb_csum_unnecessary(skb);
1330         scratch->is_linear = !skb_is_nonlinear(skb);
1331 #endif
1332         if (udp_try_make_stateless(skb))
1333                 scratch->_tsize_state |= UDP_SKB_IS_STATELESS;
1334 }
1335 
1336 static void udp_skb_csum_unnecessary_set(struct sk_buff *skb)
1337 {
1338         /* We come here after udp_lib_checksum_complete() returned 0.
1339          * This means that __skb_checksum_complete() might have
1340          * set skb->csum_valid to 1.
1341          * On 64bit platforms, we can set csum_unnecessary
1342          * to true, but only if the skb is not shared.
1343          */
1344 #if BITS_PER_LONG == 64
1345         if (!skb_shared(skb))
1346                 udp_skb_scratch(skb)->csum_unnecessary = true;
1347 #endif
1348 }
1349 
1350 static int udp_skb_truesize(struct sk_buff *skb)
1351 {
1352         return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS;
1353 }
1354 
1355 static bool udp_skb_has_head_state(struct sk_buff *skb)
1356 {
1357         return !(udp_skb_scratch(skb)->_tsize_state & UDP_SKB_IS_STATELESS);
1358 }
1359 
1360 /* fully reclaim rmem/fwd memory allocated for skb */
1361 static void udp_rmem_release(struct sock *sk, int size, int partial,
1362                              bool rx_queue_lock_held)
1363 {
1364         struct udp_sock *up = udp_sk(sk);
1365         struct sk_buff_head *sk_queue;
1366         int amt;
1367 
1368         if (likely(partial)) {
1369                 up->forward_deficit += size;
1370                 size = up->forward_deficit;
1371                 if (size < (sk->sk_rcvbuf >> 2) &&
1372                     !skb_queue_empty(&up->reader_queue))
1373                         return;
1374         } else {
1375                 size += up->forward_deficit;
1376         }
1377         up->forward_deficit = 0;
1378 
1379         /* acquire the sk_receive_queue for fwd allocated memory scheduling,
1380          * if the called don't held it already
1381          */
1382         sk_queue = &sk->sk_receive_queue;
1383         if (!rx_queue_lock_held)
1384                 spin_lock(&sk_queue->lock);
1385 
1386 
1387         sk->sk_forward_alloc += size;
1388         amt = (sk->sk_forward_alloc - partial) & ~(SK_MEM_QUANTUM - 1);
1389         sk->sk_forward_alloc -= amt;
1390 
1391         if (amt)
1392                 __sk_mem_reduce_allocated(sk, amt >> SK_MEM_QUANTUM_SHIFT);
1393 
1394         atomic_sub(size, &sk->sk_rmem_alloc);
1395 
1396         /* this can save us from acquiring the rx queue lock on next receive */
1397         skb_queue_splice_tail_init(sk_queue, &up->reader_queue);
1398 
1399         if (!rx_queue_lock_held)
1400                 spin_unlock(&sk_queue->lock);
1401 }
1402 
1403 /* Note: called with reader_queue.lock held.
1404  * Instead of using skb->truesize here, find a copy of it in skb->dev_scratch
1405  * This avoids a cache line miss while receive_queue lock is held.
1406  * Look at __udp_enqueue_schedule_skb() to find where this copy is done.
1407  */
1408 void udp_skb_destructor(struct sock *sk, struct sk_buff *skb)
1409 {
1410         prefetch(&skb->data);
1411         udp_rmem_release(sk, udp_skb_truesize(skb), 1, false);
1412 }
1413 EXPORT_SYMBOL(udp_skb_destructor);
1414 
1415 /* as above, but the caller held the rx queue lock, too */
1416 static void udp_skb_dtor_locked(struct sock *sk, struct sk_buff *skb)
1417 {
1418         prefetch(&skb->data);
1419         udp_rmem_release(sk, udp_skb_truesize(skb), 1, true);
1420 }
1421 
1422 /* Idea of busylocks is to let producers grab an extra spinlock
1423  * to relieve pressure on the receive_queue spinlock shared by consumer.
1424  * Under flood, this means that only one producer can be in line
1425  * trying to acquire the receive_queue spinlock.
1426  * These busylock can be allocated on a per cpu manner, instead of a
1427  * per socket one (that would consume a cache line per socket)
1428  */
1429 static int udp_busylocks_log __read_mostly;
1430 static spinlock_t *udp_busylocks __read_mostly;
1431 
1432 static spinlock_t *busylock_acquire(void *ptr)
1433 {
1434         spinlock_t *busy;
1435 
1436         busy = udp_busylocks + hash_ptr(ptr, udp_busylocks_log);
1437         spin_lock(busy);
1438         return busy;
1439 }
1440 
1441 static void busylock_release(spinlock_t *busy)
1442 {
1443         if (busy)
1444                 spin_unlock(busy);
1445 }
1446 
1447 int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
1448 {
1449         struct sk_buff_head *list = &sk->sk_receive_queue;
1450         int rmem, delta, amt, err = -ENOMEM;
1451         spinlock_t *busy = NULL;
1452         int size;
1453 
1454         /* try to avoid the costly atomic add/sub pair when the receive
1455          * queue is full; always allow at least a packet
1456          */
1457         rmem = atomic_read(&sk->sk_rmem_alloc);
1458         if (rmem > sk->sk_rcvbuf)
1459                 goto drop;
1460 
1461         /* Under mem pressure, it might be helpful to help udp_recvmsg()
1462          * having linear skbs :
1463          * - Reduce memory overhead and thus increase receive queue capacity
1464          * - Less cache line misses at copyout() time
1465          * - Less work at consume_skb() (less alien page frag freeing)
1466          */
1467         if (rmem > (sk->sk_rcvbuf >> 1)) {
1468                 skb_condense(skb);
1469 
1470                 busy = busylock_acquire(sk);
1471         }
1472         size = skb->truesize;
1473         udp_set_dev_scratch(skb);
1474 
1475         /* we drop only if the receive buf is full and the receive
1476          * queue contains some other skb
1477          */
1478         rmem = atomic_add_return(size, &sk->sk_rmem_alloc);
1479         if (rmem > (size + (unsigned int)sk->sk_rcvbuf))
1480                 goto uncharge_drop;
1481 
1482         spin_lock(&list->lock);
1483         if (size >= sk->sk_forward_alloc) {
1484                 amt = sk_mem_pages(size);
1485                 delta = amt << SK_MEM_QUANTUM_SHIFT;
1486                 if (!__sk_mem_raise_allocated(sk, delta, amt, SK_MEM_RECV)) {
1487                         err = -ENOBUFS;
1488                         spin_unlock(&list->lock);
1489                         goto uncharge_drop;
1490                 }
1491 
1492                 sk->sk_forward_alloc += delta;
1493         }
1494 
1495         sk->sk_forward_alloc -= size;
1496 
1497         /* no need to setup a destructor, we will explicitly release the
1498          * forward allocated memory on dequeue
1499          */
1500         sock_skb_set_dropcount(sk, skb);
1501 
1502         __skb_queue_tail(list, skb);
1503         spin_unlock(&list->lock);
1504 
1505         if (!sock_flag(sk, SOCK_DEAD))
1506                 sk->sk_data_ready(sk);
1507 
1508         busylock_release(busy);
1509         return 0;
1510 
1511 uncharge_drop:
1512         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
1513 
1514 drop:
1515         atomic_inc(&sk->sk_drops);
1516         busylock_release(busy);
1517         return err;
1518 }
1519 EXPORT_SYMBOL_GPL(__udp_enqueue_schedule_skb);
1520 
1521 void udp_destruct_sock(struct sock *sk)
1522 {
1523         /* reclaim completely the forward allocated memory */
1524         struct udp_sock *up = udp_sk(sk);
1525         unsigned int total = 0;
1526         struct sk_buff *skb;
1527 
1528         skb_queue_splice_tail_init(&sk->sk_receive_queue, &up->reader_queue);
1529         while ((skb = __skb_dequeue(&up->reader_queue)) != NULL) {
1530                 total += skb->truesize;
1531                 kfree_skb(skb);
1532         }
1533         udp_rmem_release(sk, total, 0, true);
1534 
1535         inet_sock_destruct(sk);
1536 }
1537 EXPORT_SYMBOL_GPL(udp_destruct_sock);
1538 
1539 int udp_init_sock(struct sock *sk)
1540 {
1541         skb_queue_head_init(&udp_sk(sk)->reader_queue);
1542         sk->sk_destruct = udp_destruct_sock;
1543         return 0;
1544 }
1545 EXPORT_SYMBOL_GPL(udp_init_sock);
1546 
1547 void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
1548 {
1549         if (unlikely(READ_ONCE(sk->sk_peek_off) >= 0)) {
1550                 bool slow = lock_sock_fast(sk);
1551 
1552                 sk_peek_offset_bwd(sk, len);
1553                 unlock_sock_fast(sk, slow);
1554         }
1555 
1556         if (!skb_unref(skb))
1557                 return;
1558 
1559         /* In the more common cases we cleared the head states previously,
1560          * see __udp_queue_rcv_skb().
1561          */
1562         if (unlikely(udp_skb_has_head_state(skb)))
1563                 skb_release_head_state(skb);
1564         __consume_stateless_skb(skb);
1565 }
1566 EXPORT_SYMBOL_GPL(skb_consume_udp);
1567 
1568 static struct sk_buff *__first_packet_length(struct sock *sk,
1569                                              struct sk_buff_head *rcvq,
1570                                              int *total)
1571 {
1572         struct sk_buff *skb;
1573 
1574         while ((skb = skb_peek(rcvq)) != NULL) {
1575                 if (udp_lib_checksum_complete(skb)) {
1576                         __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS,
1577                                         IS_UDPLITE(sk));
1578                         __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS,
1579                                         IS_UDPLITE(sk));
1580                         atomic_inc(&sk->sk_drops);
1581                         __skb_unlink(skb, rcvq);
1582                         *total += skb->truesize;
1583                         kfree_skb(skb);
1584                 } else {
1585                         udp_skb_csum_unnecessary_set(skb);
1586                         break;
1587                 }
1588         }
1589         return skb;
1590 }
1591 
1592 /**
1593  *      first_packet_length     - return length of first packet in receive queue
1594  *      @sk: socket
1595  *
1596  *      Drops all bad checksum frames, until a valid one is found.
1597  *      Returns the length of found skb, or -1 if none is found.
1598  */
1599 static int first_packet_length(struct sock *sk)
1600 {
1601         struct sk_buff_head *rcvq = &udp_sk(sk)->reader_queue;
1602         struct sk_buff_head *sk_queue = &sk->sk_receive_queue;
1603         struct sk_buff *skb;
1604         int total = 0;
1605         int res;
1606 
1607         spin_lock_bh(&rcvq->lock);
1608         skb = __first_packet_length(sk, rcvq, &total);
1609         if (!skb && !skb_queue_empty_lockless(sk_queue)) {
1610                 spin_lock(&sk_queue->lock);
1611                 skb_queue_splice_tail_init(sk_queue, rcvq);
1612                 spin_unlock(&sk_queue->lock);
1613 
1614                 skb = __first_packet_length(sk, rcvq, &total);
1615         }
1616         res = skb ? skb->len : -1;
1617         if (total)
1618                 udp_rmem_release(sk, total, 1, false);
1619         spin_unlock_bh(&rcvq->lock);
1620         return res;
1621 }
1622 
1623 /*
1624  *      IOCTL requests applicable to the UDP protocol
1625  */
1626 
1627 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
1628 {
1629         switch (cmd) {
1630         case SIOCOUTQ:
1631         {
1632                 int amount = sk_wmem_alloc_get(sk);
1633 
1634                 return put_user(amount, (int __user *)arg);
1635         }
1636 
1637         case SIOCINQ:
1638         {
1639                 int amount = max_t(int, 0, first_packet_length(sk));
1640 
1641                 return put_user(amount, (int __user *)arg);
1642         }
1643 
1644         default:
1645                 return -ENOIOCTLCMD;
1646         }
1647 
1648         return 0;
1649 }
1650 EXPORT_SYMBOL(udp_ioctl);
1651 
1652 struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
1653                                int noblock, int *off, int *err)
1654 {
1655         struct sk_buff_head *sk_queue = &sk->sk_receive_queue;
1656         struct sk_buff_head *queue;
1657         struct sk_buff *last;
1658         long timeo;
1659         int error;
1660 
1661         queue = &udp_sk(sk)->reader_queue;
1662         flags |= noblock ? MSG_DONTWAIT : 0;
1663         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1664         do {
1665                 struct sk_buff *skb;
1666 
1667                 error = sock_error(sk);
1668                 if (error)
1669                         break;
1670 
1671                 error = -EAGAIN;
1672                 do {
1673                         spin_lock_bh(&queue->lock);
1674                         skb = __skb_try_recv_from_queue(sk, queue, flags,
1675                                                         udp_skb_destructor,
1676                                                         off, err, &last);
1677                         if (skb) {
1678                                 spin_unlock_bh(&queue->lock);
1679                                 return skb;
1680                         }
1681 
1682                         if (skb_queue_empty_lockless(sk_queue)) {
1683                                 spin_unlock_bh(&queue->lock);
1684                                 goto busy_check;
1685                         }
1686 
1687                         /* refill the reader queue and walk it again
1688                          * keep both queues locked to avoid re-acquiring
1689                          * the sk_receive_queue lock if fwd memory scheduling
1690                          * is needed.
1691                          */
1692                         spin_lock(&sk_queue->lock);
1693                         skb_queue_splice_tail_init(sk_queue, queue);
1694 
1695                         skb = __skb_try_recv_from_queue(sk, queue, flags,
1696                                                         udp_skb_dtor_locked,
1697                                                         off, err, &last);
1698                         spin_unlock(&sk_queue->lock);
1699                         spin_unlock_bh(&queue->lock);
1700                         if (skb)
1701                                 return skb;
1702 
1703 busy_check:
1704                         if (!sk_can_busy_loop(sk))
1705                                 break;
1706 
1707                         sk_busy_loop(sk, flags & MSG_DONTWAIT);
1708                 } while (!skb_queue_empty_lockless(sk_queue));
1709 
1710                 /* sk_queue is empty, reader_queue may contain peeked packets */
1711         } while (timeo &&
1712                  !__skb_wait_for_more_packets(sk, &sk->sk_receive_queue,
1713                                               &error, &timeo,
1714                                               (struct sk_buff *)sk_queue));
1715 
1716         *err = error;
1717         return NULL;
1718 }
1719 EXPORT_SYMBOL(__skb_recv_udp);
1720 
1721 /*
1722  *      This should be easy, if there is something there we
1723  *      return it, otherwise we block.
1724  */
1725 
1726 int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
1727                 int flags, int *addr_len)
1728 {
1729         struct inet_sock *inet = inet_sk(sk);
1730         DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
1731         struct sk_buff *skb;
1732         unsigned int ulen, copied;
1733         int off, err, peeking = flags & MSG_PEEK;
1734         int is_udplite = IS_UDPLITE(sk);
1735         bool checksum_valid = false;
1736 
1737         if (flags & MSG_ERRQUEUE)
1738                 return ip_recv_error(sk, msg, len, addr_len);
1739 
1740 try_again:
1741         off = sk_peek_offset(sk, flags);
1742         skb = __skb_recv_udp(sk, flags, noblock, &off, &err);
1743         if (!skb)
1744                 return err;
1745         if (ccs_socket_post_recvmsg_permission(sk, skb, flags))
1746                 return -EAGAIN; /* Hope less harmful than -EPERM. */
1747 
1748         ulen = udp_skb_len(skb);
1749         copied = len;
1750         if (copied > ulen - off)
1751                 copied = ulen - off;
1752         else if (copied < ulen)
1753                 msg->msg_flags |= MSG_TRUNC;
1754 
1755         /*
1756          * If checksum is needed at all, try to do it while copying the
1757          * data.  If the data is truncated, or if we only want a partial
1758          * coverage checksum (UDP-Lite), do it before the copy.
1759          */
1760 
1761         if (copied < ulen || peeking ||
1762             (is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
1763                 checksum_valid = udp_skb_csum_unnecessary(skb) ||
1764                                 !__udp_lib_checksum_complete(skb);
1765                 if (!checksum_valid)
1766                         goto csum_copy_err;
1767         }
1768 
1769         if (checksum_valid || udp_skb_csum_unnecessary(skb)) {
1770                 if (udp_skb_is_linear(skb))
1771                         err = copy_linear_skb(skb, copied, off, &msg->msg_iter);
1772                 else
1773                         err = skb_copy_datagram_msg(skb, off, msg, copied);
1774         } else {
1775                 err = skb_copy_and_csum_datagram_msg(skb, off, msg);
1776 
1777                 if (err == -EINVAL)
1778                         goto csum_copy_err;
1779         }
1780 
1781         if (unlikely(err)) {
1782                 if (!peeking) {
1783                         atomic_inc(&sk->sk_drops);
1784                         UDP_INC_STATS(sock_net(sk),
1785                                       UDP_MIB_INERRORS, is_udplite);
1786                 }
1787                 kfree_skb(skb);
1788                 return err;
1789         }
1790 
1791         if (!peeking)
1792                 UDP_INC_STATS(sock_net(sk),
1793                               UDP_MIB_INDATAGRAMS, is_udplite);
1794 
1795         sock_recv_ts_and_drops(msg, sk, skb);
1796 
1797         /* Copy the address. */
1798         if (sin) {
1799                 sin->sin_family = AF_INET;
1800                 sin->sin_port = udp_hdr(skb)->source;
1801                 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
1802                 memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
1803                 *addr_len = sizeof(*sin);
1804 
1805                 if (cgroup_bpf_enabled)
1806                         BPF_CGROUP_RUN_PROG_UDP4_RECVMSG_LOCK(sk,
1807                                                         (struct sockaddr *)sin);
1808         }
1809 
1810         if (udp_sk(sk)->gro_enabled)
1811                 udp_cmsg_recv(msg, sk, skb);
1812 
1813         if (inet->cmsg_flags)
1814                 ip_cmsg_recv_offset(msg, sk, skb, sizeof(struct udphdr), off);
1815 
1816         err = copied;
1817         if (flags & MSG_TRUNC)
1818                 err = ulen;
1819 
1820         skb_consume_udp(sk, skb, peeking ? -err : err);
1821         return err;
1822 
1823 csum_copy_err:
1824         if (!__sk_queue_drop_skb(sk, &udp_sk(sk)->reader_queue, skb, flags,
1825                                  udp_skb_destructor)) {
1826                 UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
1827                 UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1828         }
1829         kfree_skb(skb);
1830 
1831         /* starting over for a new packet, but check if we need to yield */
1832         cond_resched();
1833         msg->msg_flags &= ~MSG_TRUNC;
1834         goto try_again;
1835 }
1836 
1837 int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
1838 {
1839         /* This check is replicated from __ip4_datagram_connect() and
1840          * intended to prevent BPF program called below from accessing bytes
1841          * that are out of the bound specified by user in addr_len.
1842          */
1843         if (addr_len < sizeof(struct sockaddr_in))
1844                 return -EINVAL;
1845 
1846         return BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr);
1847 }
1848 EXPORT_SYMBOL(udp_pre_connect);
1849 
1850 int __udp_disconnect(struct sock *sk, int flags)
1851 {
1852         struct inet_sock *inet = inet_sk(sk);
1853         /*
1854          *      1003.1g - break association.
1855          */
1856 
1857         sk->sk_state = TCP_CLOSE;
1858         inet->inet_daddr = 0;
1859         inet->inet_dport = 0;
1860         sock_rps_reset_rxhash(sk);
1861         sk->sk_bound_dev_if = 0;
1862         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK)) {
1863                 inet_reset_saddr(sk);
1864                 if (sk->sk_prot->rehash &&
1865                     (sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1866                         sk->sk_prot->rehash(sk);
1867         }
1868 
1869         if (!(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) {
1870                 sk->sk_prot->unhash(sk);
1871                 inet->inet_sport = 0;
1872         }
1873         sk_dst_reset(sk);
1874         return 0;
1875 }
1876 EXPORT_SYMBOL(__udp_disconnect);
1877 
1878 int udp_disconnect(struct sock *sk, int flags)
1879 {
1880         lock_sock(sk);
1881         __udp_disconnect(sk, flags);
1882         release_sock(sk);
1883         return 0;
1884 }
1885 EXPORT_SYMBOL(udp_disconnect);
1886 
1887 void udp_lib_unhash(struct sock *sk)
1888 {
1889         if (sk_hashed(sk)) {
1890                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
1891                 struct udp_hslot *hslot, *hslot2;
1892 
1893                 hslot  = udp_hashslot(udptable, sock_net(sk),
1894                                       udp_sk(sk)->udp_port_hash);
1895                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
1896 
1897                 spin_lock_bh(&hslot->lock);
1898                 if (rcu_access_pointer(sk->sk_reuseport_cb))
1899                         reuseport_detach_sock(sk);
1900                 if (sk_del_node_init_rcu(sk)) {
1901                         hslot->count--;
1902                         inet_sk(sk)->inet_num = 0;
1903                         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
1904 
1905                         spin_lock(&hslot2->lock);
1906                         hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
1907                         hslot2->count--;
1908                         spin_unlock(&hslot2->lock);
1909                 }
1910                 spin_unlock_bh(&hslot->lock);
1911         }
1912 }
1913 EXPORT_SYMBOL(udp_lib_unhash);
1914 
1915 /*
1916  * inet_rcv_saddr was changed, we must rehash secondary hash
1917  */
1918 void udp_lib_rehash(struct sock *sk, u16 newhash)
1919 {
1920         if (sk_hashed(sk)) {
1921                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
1922                 struct udp_hslot *hslot, *hslot2, *nhslot2;
1923 
1924                 hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
1925                 nhslot2 = udp_hashslot2(udptable, newhash);
1926                 udp_sk(sk)->udp_portaddr_hash = newhash;
1927 
1928                 if (hslot2 != nhslot2 ||
1929                     rcu_access_pointer(sk->sk_reuseport_cb)) {
1930                         hslot = udp_hashslot(udptable, sock_net(sk),
1931                                              udp_sk(sk)->udp_port_hash);
1932                         /* we must lock primary chain too */
1933                         spin_lock_bh(&hslot->lock);
1934                         if (rcu_access_pointer(sk->sk_reuseport_cb))
1935                                 reuseport_detach_sock(sk);
1936 
1937                         if (hslot2 != nhslot2) {
1938                                 spin_lock(&hslot2->lock);
1939                                 hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
1940                                 hslot2->count--;
1941                                 spin_unlock(&hslot2->lock);
1942 
1943                                 spin_lock(&nhslot2->lock);
1944                                 hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
1945                                                          &nhslot2->head);
1946                                 nhslot2->count++;
1947                                 spin_unlock(&nhslot2->lock);
1948                         }
1949 
1950                         spin_unlock_bh(&hslot->lock);
1951                 }
1952         }
1953 }
1954 EXPORT_SYMBOL(udp_lib_rehash);
1955 
1956 void udp_v4_rehash(struct sock *sk)
1957 {
1958         u16 new_hash = ipv4_portaddr_hash(sock_net(sk),
1959                                           inet_sk(sk)->inet_rcv_saddr,
1960                                           inet_sk(sk)->inet_num);
1961         udp_lib_rehash(sk, new_hash);
1962 }
1963 
1964 static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
1965 {
1966         int rc;
1967 
1968         if (inet_sk(sk)->inet_daddr) {
1969                 sock_rps_save_rxhash(sk, skb);
1970                 sk_mark_napi_id(sk, skb);
1971                 sk_incoming_cpu_update(sk);
1972         } else {
1973                 sk_mark_napi_id_once(sk, skb);
1974         }
1975 
1976         rc = __udp_enqueue_schedule_skb(sk, skb);
1977         if (rc < 0) {
1978                 int is_udplite = IS_UDPLITE(sk);
1979 
1980                 /* Note that an ENOMEM error is charged twice */
1981                 if (rc == -ENOMEM)
1982                         UDP_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS,
1983                                         is_udplite);
1984                 UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
1985                 kfree_skb(skb);
1986                 trace_udp_fail_queue_rcv_skb(rc, sk);
1987                 return -1;
1988         }
1989 
1990         return 0;
1991 }
1992 
1993 /* returns:
1994  *  -1: error
1995  *   0: success
1996  *  >0: "udp encap" protocol resubmission
1997  *
1998  * Note that in the success and error cases, the skb is assumed to
1999  * have either been requeued or freed.
2000  */
2001 static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
2002 {
2003         struct udp_sock *up = udp_sk(sk);
2004         int is_udplite = IS_UDPLITE(sk);
2005 
2006         /*
2007          *      Charge it to the socket, dropping if the queue is full.
2008          */
2009         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
2010                 goto drop;
2011         nf_reset_ct(skb);
2012 
2013         if (static_branch_unlikely(&udp_encap_needed_key) && up->encap_type) {
2014                 int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
2015 
2016                 /*
2017                  * This is an encapsulation socket so pass the skb to
2018                  * the socket's udp_encap_rcv() hook. Otherwise, just
2019                  * fall through and pass this up the UDP socket.
2020                  * up->encap_rcv() returns the following value:
2021                  * =0 if skb was successfully passed to the encap
2022                  *    handler or was discarded by it.
2023                  * >0 if skb should be passed on to UDP.
2024                  * <0 if skb should be resubmitted as proto -N
2025                  */
2026 
2027                 /* if we're overly short, let UDP handle it */
2028                 encap_rcv = READ_ONCE(up->encap_rcv);
2029                 if (encap_rcv) {
2030                         int ret;
2031 
2032                         /* Verify checksum before giving to encap */
2033                         if (udp_lib_checksum_complete(skb))
2034                                 goto csum_error;
2035 
2036                         ret = encap_rcv(sk, skb);
2037                         if (ret <= 0) {
2038                                 __UDP_INC_STATS(sock_net(sk),
2039                                                 UDP_MIB_INDATAGRAMS,
2040                                                 is_udplite);
2041                                 return -ret;
2042                         }
2043                 }
2044 
2045                 /* FALLTHROUGH -- it's a UDP Packet */
2046         }
2047 
2048         /*
2049          *      UDP-Lite specific tests, ignored on UDP sockets
2050          */
2051         if ((is_udplite & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
2052 
2053                 /*
2054                  * MIB statistics other than incrementing the error count are
2055                  * disabled for the following two types of errors: these depend
2056                  * on the application settings, not on the functioning of the
2057                  * protocol stack as such.
2058                  *
2059                  * RFC 3828 here recommends (sec 3.3): "There should also be a
2060                  * way ... to ... at least let the receiving application block
2061                  * delivery of packets with coverage values less than a value
2062                  * provided by the application."
2063                  */
2064                 if (up->pcrlen == 0) {          /* full coverage was set  */
2065                         net_dbg_ratelimited("UDPLite: partial coverage %d while full coverage %d requested\n",
2066                                             UDP_SKB_CB(skb)->cscov, skb->len);
2067                         goto drop;
2068                 }
2069                 /* The next case involves violating the min. coverage requested
2070                  * by the receiver. This is subtle: if receiver wants x and x is
2071                  * greater than the buffersize/MTU then receiver will complain
2072                  * that it wants x while sender emits packets of smaller size y.
2073                  * Therefore the above ...()->partial_cov statement is essential.
2074                  */
2075                 if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
2076                         net_dbg_ratelimited("UDPLite: coverage %d too small, need min %d\n",
2077                                             UDP_SKB_CB(skb)->cscov, up->pcrlen);
2078                         goto drop;
2079                 }
2080         }
2081 
2082         prefetch(&sk->sk_rmem_alloc);
2083         if (rcu_access_pointer(sk->sk_filter) &&
2084             udp_lib_checksum_complete(skb))
2085                         goto csum_error;
2086 
2087         if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr)))
2088                 goto drop;
2089 
2090         udp_csum_pull_header(skb);
2091 
2092         ipv4_pktinfo_prepare(sk, skb);
2093         return __udp_queue_rcv_skb(sk, skb);
2094 
2095 csum_error:
2096         __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
2097 drop:
2098         __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
2099         atomic_inc(&sk->sk_drops);
2100         kfree_skb(skb);
2101         return -1;
2102 }
2103 
2104 static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
2105 {
2106         struct sk_buff *next, *segs;
2107         int ret;
2108 
2109         if (likely(!udp_unexpected_gso(sk, skb)))
2110                 return udp_queue_rcv_one_skb(sk, skb);
2111 
2112         BUILD_BUG_ON(sizeof(struct udp_skb_cb) > SKB_SGO_CB_OFFSET);
2113         __skb_push(skb, -skb_mac_offset(skb));
2114         segs = udp_rcv_segment(sk, skb, true);
2115         skb_list_walk_safe(segs, skb, next) {
2116                 __skb_pull(skb, skb_transport_offset(skb));
2117                 ret = udp_queue_rcv_one_skb(sk, skb);
2118                 if (ret > 0)
2119                         ip_protocol_deliver_rcu(dev_net(skb->dev), skb, -ret);
2120         }
2121         return 0;
2122 }
2123 
2124 /* For TCP sockets, sk_rx_dst is protected by socket lock
2125  * For UDP, we use xchg() to guard against concurrent changes.
2126  */
2127 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
2128 {
2129         struct dst_entry *old;
2130 
2131         if (dst_hold_safe(dst)) {
2132                 old = xchg(&sk->sk_rx_dst, dst);
2133                 dst_release(old);
2134                 return old != dst;
2135         }
2136         return false;
2137 }
2138 EXPORT_SYMBOL(udp_sk_rx_dst_set);
2139 
2140 /*
2141  *      Multicasts and broadcasts go to each listener.
2142  *
2143  *      Note: called only from the BH handler context.
2144  */
2145 static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
2146                                     struct udphdr  *uh,
2147                                     __be32 saddr, __be32 daddr,
2148                                     struct udp_table *udptable,
2149                                     int proto)
2150 {
2151         struct sock *sk, *first = NULL;
2152         unsigned short hnum = ntohs(uh->dest);
2153         struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum);
2154         unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
2155         unsigned int offset = offsetof(typeof(*sk), sk_node);
2156         int dif = skb->dev->ifindex;
2157         int sdif = inet_sdif(skb);
2158         struct hlist_node *node;
2159         struct sk_buff *nskb;
2160 
2161         if (use_hash2) {
2162                 hash2_any = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum) &
2163                             udptable->mask;
2164                 hash2 = ipv4_portaddr_hash(net, daddr, hnum) & udptable->mask;
2165 start_lookup:
2166                 hslot = &udptable->hash2[hash2];
2167                 offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node);
2168         }
2169 
2170         sk_for_each_entry_offset_rcu(sk, node, &hslot->head, offset) {
2171                 if (!__udp_is_mcast_sock(net, sk, uh->dest, daddr,
2172                                          uh->source, saddr, dif, sdif, hnum))
2173                         continue;
2174 
2175                 if (!first) {
2176                         first = sk;
2177                         continue;
2178                 }
2179                 nskb = skb_clone(skb, GFP_ATOMIC);
2180 
2181                 if (unlikely(!nskb)) {
2182                         atomic_inc(&sk->sk_drops);
2183                         __UDP_INC_STATS(net, UDP_MIB_RCVBUFERRORS,
2184                                         IS_UDPLITE(sk));
2185                         __UDP_INC_STATS(net, UDP_MIB_INERRORS,
2186                                         IS_UDPLITE(sk));
2187                         continue;
2188                 }
2189                 if (udp_queue_rcv_skb(sk, nskb) > 0)
2190                         consume_skb(nskb);
2191         }
2192 
2193         /* Also lookup *:port if we are using hash2 and haven't done so yet. */
2194         if (use_hash2 && hash2 != hash2_any) {
2195                 hash2 = hash2_any;
2196                 goto start_lookup;
2197         }
2198 
2199         if (first) {
2200                 if (udp_queue_rcv_skb(first, skb) > 0)
2201                         consume_skb(skb);
2202         } else {
2203                 kfree_skb(skb);
2204                 __UDP_INC_STATS(net, UDP_MIB_IGNOREDMULTI,
2205                                 proto == IPPROTO_UDPLITE);
2206         }
2207         return 0;
2208 }
2209 
2210 /* Initialize UDP checksum. If exited with zero value (success),
2211  * CHECKSUM_UNNECESSARY means, that no more checks are required.
2212  * Otherwise, csum completion requires checksumming packet body,
2213  * including udp header and folding it to skb->csum.
2214  */
2215 static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,
2216                                  int proto)
2217 {
2218         int err;
2219 
2220         UDP_SKB_CB(skb)->partial_cov = 0;
2221         UDP_SKB_CB(skb)->cscov = skb->len;
2222 
2223         if (proto == IPPROTO_UDPLITE) {
2224                 err = udplite_checksum_init(skb, uh);
2225                 if (err)
2226                         return err;
2227 
2228                 if (UDP_SKB_CB(skb)->partial_cov) {
2229                         skb->csum = inet_compute_pseudo(skb, proto);
2230                         return 0;
2231                 }
2232         }
2233 
2234         /* Note, we are only interested in != 0 or == 0, thus the
2235          * force to int.
2236          */
2237         err = (__force int)skb_checksum_init_zero_check(skb, proto, uh->check,
2238                                                         inet_compute_pseudo);
2239         if (err)
2240                 return err;
2241 
2242         if (skb->ip_summed == CHECKSUM_COMPLETE && !skb->csum_valid) {
2243                 /* If SW calculated the value, we know it's bad */
2244                 if (skb->csum_complete_sw)
2245                         return 1;
2246 
2247                 /* HW says the value is bad. Let's validate that.
2248                  * skb->csum is no longer the full packet checksum,
2249                  * so don't treat it as such.
2250                  */
2251                 skb_checksum_complete_unset(skb);
2252         }
2253 
2254         return 0;
2255 }
2256 
2257 /* wrapper for udp_queue_rcv_skb tacking care of csum conversion and
2258  * return code conversion for ip layer consumption
2259  */
2260 static int udp_unicast_rcv_skb(struct sock *sk, struct sk_buff *skb,
2261                                struct udphdr *uh)
2262 {
2263         int ret;
2264 
2265         if (inet_get_convert_csum(sk) && uh->check && !IS_UDPLITE(sk))
2266                 skb_checksum_try_convert(skb, IPPROTO_UDP, inet_compute_pseudo);
2267 
2268         ret = udp_queue_rcv_skb(sk, skb);
2269 
2270         /* a return value > 0 means to resubmit the input, but
2271          * it wants the return to be -protocol, or 0
2272          */
2273         if (ret > 0)
2274                 return -ret;
2275         return 0;
2276 }
2277 
2278 /*
2279  *      All we need to do is get the socket, and then do a checksum.
2280  */
2281 
2282 int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
2283                    int proto)
2284 {
2285         struct sock *sk;
2286         struct udphdr *uh;
2287         unsigned short ulen;
2288         struct rtable *rt = skb_rtable(skb);
2289         __be32 saddr, daddr;
2290         struct net *net = dev_net(skb->dev);
2291 
2292         /*
2293          *  Validate the packet.
2294          */
2295         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
2296                 goto drop;              /* No space for header. */
2297 
2298         uh   = udp_hdr(skb);
2299         ulen = ntohs(uh->len);
2300         saddr = ip_hdr(skb)->saddr;
2301         daddr = ip_hdr(skb)->daddr;
2302 
2303         if (ulen > skb->len)
2304                 goto short_packet;
2305 
2306         if (proto == IPPROTO_UDP) {
2307                 /* UDP validates ulen. */
2308                 if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen))
2309                         goto short_packet;
2310                 uh = udp_hdr(skb);
2311         }
2312 
2313         if (udp4_csum_init(skb, uh, proto))
2314                 goto csum_error;
2315 
2316         sk = skb_steal_sock(skb);
2317         if (sk) {
2318                 struct dst_entry *dst = skb_dst(skb);
2319                 int ret;
2320 
2321                 if (unlikely(sk->sk_rx_dst != dst))
2322                         udp_sk_rx_dst_set(sk, dst);
2323 
2324                 ret = udp_unicast_rcv_skb(sk, skb, uh);
2325                 sock_put(sk);
2326                 return ret;
2327         }
2328 
2329         if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
2330                 return __udp4_lib_mcast_deliver(net, skb, uh,
2331                                                 saddr, daddr, udptable, proto);
2332 
2333         sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
2334         if (sk)
2335                 return udp_unicast_rcv_skb(sk, skb, uh);
2336 
2337         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
2338                 goto drop;
2339         nf_reset_ct(skb);
2340 
2341         /* No socket. Drop packet silently, if checksum is wrong */
2342         if (udp_lib_checksum_complete(skb))
2343                 goto csum_error;
2344 
2345         __UDP_INC_STATS(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
2346         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
2347 
2348         /*
2349          * Hmm.  We got an UDP packet to a port to which we
2350          * don't wanna listen.  Ignore it.
2351          */
2352         kfree_skb(skb);
2353         return 0;
2354 
2355 short_packet:
2356         net_dbg_ratelimited("UDP%s: short packet: From %pI4:%u %d/%d to %pI4:%u\n",
2357                             proto == IPPROTO_UDPLITE ? "Lite" : "",
2358                             &saddr, ntohs(uh->source),
2359                             ulen, skb->len,
2360                             &daddr, ntohs(uh->dest));
2361         goto drop;
2362 
2363 csum_error:
2364         /*
2365          * RFC1122: OK.  Discards the bad packet silently (as far as
2366          * the network is concerned, anyway) as per 4.1.3.4 (MUST).
2367          */
2368         net_dbg_ratelimited("UDP%s: bad checksum. From %pI4:%u to %pI4:%u ulen %d\n",
2369                             proto == IPPROTO_UDPLITE ? "Lite" : "",
2370                             &saddr, ntohs(uh->source), &daddr, ntohs(uh->dest),
2371                             ulen);
2372         __UDP_INC_STATS(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE);
2373 drop:
2374         __UDP_INC_STATS(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
2375         kfree_skb(skb);
2376         return 0;
2377 }
2378 
2379 /* We can only early demux multicast if there is a single matching socket.
2380  * If more than one socket found returns NULL
2381  */
2382 static struct sock *__udp4_lib_mcast_demux_lookup(struct net *net,
2383                                                   __be16 loc_port, __be32 loc_addr,
2384                                                   __be16 rmt_port, __be32 rmt_addr,
2385                                                   int dif, int sdif)
2386 {
2387         struct sock *sk, *result;
2388         unsigned short hnum = ntohs(loc_port);
2389         unsigned int slot = udp_hashfn(net, hnum, udp_table.mask);
2390         struct udp_hslot *hslot = &udp_table.hash[slot];
2391 
2392         /* Do not bother scanning a too big list */
2393         if (hslot->count > 10)
2394                 return NULL;
2395 
2396         result = NULL;
2397         sk_for_each_rcu(sk, &hslot->head) {
2398                 if (__udp_is_mcast_sock(net, sk, loc_port, loc_addr,
2399                                         rmt_port, rmt_addr, dif, sdif, hnum)) {
2400                         if (result)
2401                                 return NULL;
2402                         result = sk;
2403                 }
2404         }
2405 
2406         return result;
2407 }
2408 
2409 /* For unicast we should only early demux connected sockets or we can
2410  * break forwarding setups.  The chains here can be long so only check
2411  * if the first socket is an exact match and if not move on.
2412  */
2413 static struct sock *__udp4_lib_demux_lookup(struct net *net,
2414                                             __be16 loc_port, __be32 loc_addr,
2415                                             __be16 rmt_port, __be32 rmt_addr,
2416                                             int dif, int sdif)
2417 {
2418         unsigned short hnum = ntohs(loc_port);
2419         unsigned int hash2 = ipv4_portaddr_hash(net, loc_addr, hnum);
2420         unsigned int slot2 = hash2 & udp_table.mask;
2421         struct udp_hslot *hslot2 = &udp_table.hash2[slot2];
2422         INET_ADDR_COOKIE(acookie, rmt_addr, loc_addr);
2423         const __portpair ports = INET_COMBINED_PORTS(rmt_port, hnum);
2424         struct sock *sk;
2425 
2426         udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
2427                 if (INET_MATCH(sk, net, acookie, rmt_addr,
2428                                loc_addr, ports, dif, sdif))
2429                         return sk;
2430                 /* Only check first socket in chain */
2431                 break;
2432         }
2433         return NULL;
2434 }
2435 
2436 int udp_v4_early_demux(struct sk_buff *skb)
2437 {
2438         struct net *net = dev_net(skb->dev);
2439         struct in_device *in_dev = NULL;
2440         const struct iphdr *iph;
2441         const struct udphdr *uh;
2442         struct sock *sk = NULL;
2443         struct dst_entry *dst;
2444         int dif = skb->dev->ifindex;
2445         int sdif = inet_sdif(skb);
2446         int ours;
2447 
2448         /* validate the packet */
2449         if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr)))
2450                 return 0;
2451 
2452         iph = ip_hdr(skb);
2453         uh = udp_hdr(skb);
2454 
2455         if (skb->pkt_type == PACKET_MULTICAST) {
2456                 in_dev = __in_dev_get_rcu(skb->dev);
2457 
2458                 if (!in_dev)
2459                         return 0;
2460 
2461                 ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
2462                                        iph->protocol);
2463                 if (!ours)
2464                         return 0;
2465 
2466                 sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr,
2467                                                    uh->source, iph->saddr,
2468                                                    dif, sdif);
2469         } else if (skb->pkt_type == PACKET_HOST) {
2470                 sk = __udp4_lib_demux_lookup(net, uh->dest, iph->daddr,
2471                                              uh->source, iph->saddr, dif, sdif);
2472         }
2473 
2474         if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
2475                 return 0;
2476 
2477         skb->sk = sk;
2478         skb->destructor = sock_efree;
2479         dst = READ_ONCE(sk->sk_rx_dst);
2480 
2481         if (dst)
2482                 dst = dst_check(dst, 0);
2483         if (dst) {
2484                 u32 itag = 0;
2485 
2486                 /* set noref for now.
2487                  * any place which wants to hold dst has to call
2488                  * dst_hold_safe()
2489                  */
2490                 skb_dst_set_noref(skb, dst);
2491 
2492                 /* for unconnected multicast sockets we need to validate
2493                  * the source on each packet
2494                  */
2495                 if (!inet_sk(sk)->inet_daddr && in_dev)
2496                         return ip_mc_validate_source(skb, iph->daddr,
2497                                                      iph->saddr, iph->tos,
2498                                                      skb->dev, in_dev, &itag);
2499         }
2500         return 0;
2501 }
2502 
2503 int udp_rcv(struct sk_buff *skb)
2504 {
2505         return __udp4_lib_rcv(skb, &udp_table, IPPROTO_UDP);
2506 }
2507 
2508 void udp_destroy_sock(struct sock *sk)
2509 {
2510         struct udp_sock *up = udp_sk(sk);
2511         bool slow = lock_sock_fast(sk);
2512         udp_flush_pending_frames(sk);
2513         unlock_sock_fast(sk, slow);
2514         if (static_branch_unlikely(&udp_encap_needed_key)) {
2515                 if (up->encap_type) {
2516                         void (*encap_destroy)(struct sock *sk);
2517                         encap_destroy = READ_ONCE(up->encap_destroy);
2518                         if (encap_destroy)
2519                                 encap_destroy(sk);
2520                 }
2521                 if (up->encap_enabled)
2522                         static_branch_dec(&udp_encap_needed_key);
2523         }
2524 }
2525 
2526 /*
2527  *      Socket option code for UDP
2528  */
2529 int udp_lib_setsockopt(struct sock *sk, int level, int optname,
2530                        char __user *optval, unsigned int optlen,
2531                        int (*push_pending_frames)(struct sock *))
2532 {
2533         struct udp_sock *up = udp_sk(sk);
2534         int val, valbool;
2535         int err = 0;
2536         int is_udplite = IS_UDPLITE(sk);
2537 
2538         if (optlen < sizeof(int))
2539                 return -EINVAL;
2540 
2541         if (get_user(val, (int __user *)optval))
2542                 return -EFAULT;
2543 
2544         valbool = val ? 1 : 0;
2545 
2546         switch (optname) {
2547         case UDP_CORK:
2548                 if (val != 0) {
2549                         up->corkflag = 1;
2550                 } else {
2551                         up->corkflag = 0;
2552                         lock_sock(sk);
2553                         push_pending_frames(sk);
2554                         release_sock(sk);
2555                 }
2556                 break;
2557 
2558         case UDP_ENCAP:
2559                 switch (val) {
2560                 case 0:
2561 #ifdef CONFIG_XFRM
2562                 case UDP_ENCAP_ESPINUDP:
2563                 case UDP_ENCAP_ESPINUDP_NON_IKE:
2564                         up->encap_rcv = xfrm4_udp_encap_rcv;
2565 #endif
2566                         /* FALLTHROUGH */
2567                 case UDP_ENCAP_L2TPINUDP:
2568                         up->encap_type = val;
2569                         lock_sock(sk);
2570                         udp_tunnel_encap_enable(sk->sk_socket);
2571                         release_sock(sk);
2572                         break;
2573                 default:
2574                         err = -ENOPROTOOPT;
2575                         break;
2576                 }
2577                 break;
2578 
2579         case UDP_NO_CHECK6_TX:
2580                 up->no_check6_tx = valbool;
2581                 break;
2582 
2583         case UDP_NO_CHECK6_RX:
2584                 up->no_check6_rx = valbool;
2585                 break;
2586 
2587         case UDP_SEGMENT:
2588                 if (val < 0 || val > USHRT_MAX)
2589                         return -EINVAL;
2590                 up->gso_size = val;
2591                 break;
2592 
2593         case UDP_GRO:
2594                 lock_sock(sk);
2595                 if (valbool)
2596                         udp_tunnel_encap_enable(sk->sk_socket);
2597                 up->gro_enabled = valbool;
2598                 release_sock(sk);
2599                 break;
2600 
2601         /*
2602          *      UDP-Lite's partial checksum coverage (RFC 3828).
2603          */
2604         /* The sender sets actual checksum coverage length via this option.
2605          * The case coverage > packet length is handled by send module. */
2606         case UDPLITE_SEND_CSCOV:
2607                 if (!is_udplite)         /* Disable the option on UDP sockets */
2608                         return -ENOPROTOOPT;
2609                 if (val != 0 && val < 8) /* Illegal coverage: use default (8) */
2610                         val = 8;
2611                 else if (val > USHRT_MAX)
2612                         val = USHRT_MAX;
2613                 up->pcslen = val;
2614                 up->pcflag |= UDPLITE_SEND_CC;
2615                 break;
2616 
2617         /* The receiver specifies a minimum checksum coverage value. To make
2618          * sense, this should be set to at least 8 (as done below). If zero is
2619          * used, this again means full checksum coverage.                     */
2620         case UDPLITE_RECV_CSCOV:
2621                 if (!is_udplite)         /* Disable the option on UDP sockets */
2622                         return -ENOPROTOOPT;
2623                 if (val != 0 && val < 8) /* Avoid silly minimal values.       */
2624                         val = 8;
2625                 else if (val > USHRT_MAX)
2626                         val = USHRT_MAX;
2627                 up->pcrlen = val;
2628                 up->pcflag |= UDPLITE_RECV_CC;
2629                 break;
2630 
2631         default:
2632                 err = -ENOPROTOOPT;
2633                 break;
2634         }
2635 
2636         return err;
2637 }
2638 EXPORT_SYMBOL(udp_lib_setsockopt);
2639 
2640 int udp_setsockopt(struct sock *sk, int level, int optname,
2641                    char __user *optval, unsigned int optlen)
2642 {
2643         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2644                 return udp_lib_setsockopt(sk, level, optname, optval, optlen,
2645                                           udp_push_pending_frames);
2646         return ip_setsockopt(sk, level, optname, optval, optlen);
2647 }
2648 
2649 #ifdef CONFIG_COMPAT
2650 int compat_udp_setsockopt(struct sock *sk, int level, int optname,
2651                           char __user *optval, unsigned int optlen)
2652 {
2653         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2654                 return udp_lib_setsockopt(sk, level, optname, optval, optlen,
2655                                           udp_push_pending_frames);
2656         return compat_ip_setsockopt(sk, level, optname, optval, optlen);
2657 }
2658 #endif
2659 
2660 int udp_lib_getsockopt(struct sock *sk, int level, int optname,
2661                        char __user *optval, int __user *optlen)
2662 {
2663         struct udp_sock *up = udp_sk(sk);
2664         int val, len;
2665 
2666         if (get_user(len, optlen))
2667                 return -EFAULT;
2668 
2669         len = min_t(unsigned int, len, sizeof(int));
2670 
2671         if (len < 0)
2672                 return -EINVAL;
2673 
2674         switch (optname) {
2675         case UDP_CORK:
2676                 val = up->corkflag;
2677                 break;
2678 
2679         case UDP_ENCAP:
2680                 val = up->encap_type;
2681                 break;
2682 
2683         case UDP_NO_CHECK6_TX:
2684                 val = up->no_check6_tx;
2685                 break;
2686 
2687         case UDP_NO_CHECK6_RX:
2688                 val = up->no_check6_rx;
2689                 break;
2690 
2691         case UDP_SEGMENT:
2692                 val = up->gso_size;
2693                 break;
2694 
2695         /* The following two cannot be changed on UDP sockets, the return is
2696          * always 0 (which corresponds to the full checksum coverage of UDP). */
2697         case UDPLITE_SEND_CSCOV:
2698                 val = up->pcslen;
2699                 break;
2700 
2701         case UDPLITE_RECV_CSCOV:
2702                 val = up->pcrlen;
2703                 break;
2704 
2705         default:
2706                 return -ENOPROTOOPT;
2707         }
2708 
2709         if (put_user(len, optlen))
2710                 return -EFAULT;
2711         if (copy_to_user(optval, &val, len))
2712                 return -EFAULT;
2713         return 0;
2714 }
2715 EXPORT_SYMBOL(udp_lib_getsockopt);
2716 
2717 int udp_getsockopt(struct sock *sk, int level, int optname,
2718                    char __user *optval, int __user *optlen)
2719 {
2720         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2721                 return udp_lib_getsockopt(sk, level, optname, optval, optlen);
2722         return ip_getsockopt(sk, level, optname, optval, optlen);
2723 }
2724 
2725 #ifdef CONFIG_COMPAT
2726 int compat_udp_getsockopt(struct sock *sk, int level, int optname,
2727                                  char __user *optval, int __user *optlen)
2728 {
2729         if (level == SOL_UDP  ||  level == SOL_UDPLITE)
2730                 return udp_lib_getsockopt(sk, level, optname, optval, optlen);
2731         return compat_ip_getsockopt(sk, level, optname, optval, optlen);
2732 }
2733 #endif
2734 /**
2735  *      udp_poll - wait for a UDP event.
2736  *      @file - file struct
2737  *      @sock - socket
2738  *      @wait - poll table
2739  *
2740  *      This is same as datagram poll, except for the special case of
2741  *      blocking sockets. If application is using a blocking fd
2742  *      and a packet with checksum error is in the queue;
2743  *      then it could get return from select indicating data available
2744  *      but then block when reading it. Add special case code
2745  *      to work around these arguably broken applications.
2746  */
2747 __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait)
2748 {
2749         __poll_t mask = datagram_poll(file, sock, wait);
2750         struct sock *sk = sock->sk;
2751 
2752         if (!skb_queue_empty_lockless(&udp_sk(sk)->reader_queue))
2753                 mask |= EPOLLIN | EPOLLRDNORM;
2754 
2755         /* Check for false positives due to checksum errors */
2756         if ((mask & EPOLLRDNORM) && !(file->f_flags & O_NONBLOCK) &&
2757             !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1)
2758                 mask &= ~(EPOLLIN | EPOLLRDNORM);
2759 
2760         return mask;
2761 
2762 }
2763 EXPORT_SYMBOL(udp_poll);
2764 
2765 int udp_abort(struct sock *sk, int err)
2766 {
2767         lock_sock(sk);
2768 
2769         sk->sk_err = err;
2770         sk->sk_error_report(sk);
2771         __udp_disconnect(sk, 0);
2772 
2773         release_sock(sk);
2774 
2775         return 0;
2776 }
2777 EXPORT_SYMBOL_GPL(udp_abort);
2778 
2779 struct proto udp_prot = {
2780         .name                   = "UDP",
2781         .owner                  = THIS_MODULE,
2782         .close                  = udp_lib_close,
2783         .pre_connect            = udp_pre_connect,
2784         .connect                = ip4_datagram_connect,
2785         .disconnect             = udp_disconnect,
2786         .ioctl                  = udp_ioctl,
2787         .init                   = udp_init_sock,
2788         .destroy                = udp_destroy_sock,
2789         .setsockopt             = udp_setsockopt,
2790         .getsockopt             = udp_getsockopt,
2791         .sendmsg                = udp_sendmsg,
2792         .recvmsg                = udp_recvmsg,
2793         .sendpage               = udp_sendpage,
2794         .release_cb             = ip4_datagram_release_cb,
2795         .hash                   = udp_lib_hash,
2796         .unhash                 = udp_lib_unhash,
2797         .rehash                 = udp_v4_rehash,
2798         .get_port               = udp_v4_get_port,
2799         .memory_allocated       = &udp_memory_allocated,
2800         .sysctl_mem             = sysctl_udp_mem,
2801         .sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
2802         .sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
2803         .obj_size               = sizeof(struct udp_sock),
2804         .h.udp_table            = &udp_table,
2805 #ifdef CONFIG_COMPAT
2806         .compat_setsockopt      = compat_udp_setsockopt,
2807         .compat_getsockopt      = compat_udp_getsockopt,
2808 #endif
2809         .diag_destroy           = udp_abort,
2810 };
2811 EXPORT_SYMBOL(udp_prot);
2812 
2813 /* ------------------------------------------------------------------------ */
2814 #ifdef CONFIG_PROC_FS
2815 
2816 static struct sock *udp_get_first(struct seq_file *seq, int start)
2817 {
2818         struct sock *sk;
2819         struct udp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file));
2820         struct udp_iter_state *state = seq->private;
2821         struct net *net = seq_file_net(seq);
2822 
2823         for (state->bucket = start; state->bucket <= afinfo->udp_table->mask;
2824              ++state->bucket) {
2825                 struct udp_hslot *hslot = &afinfo->udp_table->hash[state->bucket];
2826 
2827                 if (hlist_empty(&hslot->head))
2828                         continue;
2829 
2830                 spin_lock_bh(&hslot->lock);
2831                 sk_for_each(sk, &hslot->head) {
2832                         if (!net_eq(sock_net(sk), net))
2833                                 continue;
2834                         if (sk->sk_family == afinfo->family)
2835                                 goto found;
2836                 }
2837                 spin_unlock_bh(&hslot->lock);
2838         }
2839         sk = NULL;
2840 found:
2841         return sk;
2842 }
2843 
2844 static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
2845 {
2846         struct udp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file));
2847         struct udp_iter_state *state = seq->private;
2848         struct net *net = seq_file_net(seq);
2849 
2850         do {
2851                 sk = sk_next(sk);
2852         } while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != afinfo->family));
2853 
2854         if (!sk) {
2855                 if (state->bucket <= afinfo->udp_table->mask)
2856                         spin_unlock_bh(&afinfo->udp_table->hash[state->bucket].lock);
2857                 return udp_get_first(seq, state->bucket + 1);
2858         }
2859         return sk;
2860 }
2861 
2862 static struct sock *udp_get_idx(struct seq_file *seq, loff_t pos)
2863 {
2864         struct sock *sk = udp_get_first(seq, 0);
2865 
2866         if (sk)
2867                 while (pos && (sk = udp_get_next(seq, sk)) != NULL)
2868                         --pos;
2869         return pos ? NULL : sk;
2870 }
2871 
2872 void *udp_seq_start(struct seq_file *seq, loff_t *pos)
2873 {
2874         struct udp_iter_state *state = seq->private;
2875         state->bucket = MAX_UDP_PORTS;
2876 
2877         return *pos ? udp_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
2878 }
2879 EXPORT_SYMBOL(udp_seq_start);
2880 
2881 void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2882 {
2883         struct sock *sk;
2884 
2885         if (v == SEQ_START_TOKEN)
2886                 sk = udp_get_idx(seq, 0);
2887         else
2888                 sk = udp_get_next(seq, v);
2889 
2890         ++*pos;
2891         return sk;
2892 }
2893 EXPORT_SYMBOL(udp_seq_next);
2894 
2895 void udp_seq_stop(struct seq_file *seq, void *v)
2896 {
2897         struct udp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file));
2898         struct udp_iter_state *state = seq->private;
2899 
2900         if (state->bucket <= afinfo->udp_table->mask)
2901                 spin_unlock_bh(&afinfo->udp_table->hash[state->bucket].lock);
2902 }
2903 EXPORT_SYMBOL(udp_seq_stop);
2904 
2905 /* ------------------------------------------------------------------------ */
2906 static void udp4_format_sock(struct sock *sp, struct seq_file *f,
2907                 int bucket)
2908 {
2909         struct inet_sock *inet = inet_sk(sp);
2910         __be32 dest = inet->inet_daddr;
2911         __be32 src  = inet->inet_rcv_saddr;
2912         __u16 destp       = ntohs(inet->inet_dport);
2913         __u16 srcp        = ntohs(inet->inet_sport);
2914 
2915         seq_printf(f, "%5d: %08X:%04X %08X:%04X"
2916                 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %u",
2917                 bucket, src, srcp, dest, destp, sp->sk_state,
2918                 sk_wmem_alloc_get(sp),
2919                 udp_rqueue_get(sp),
2920                 0, 0L, 0,
2921                 from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
2922                 0, sock_i_ino(sp),
2923                 refcount_read(&sp->sk_refcnt), sp,
2924                 atomic_read(&sp->sk_drops));
2925 }
2926 
2927 int udp4_seq_show(struct seq_file *seq, void *v)
2928 {
2929         seq_setwidth(seq, 127);
2930         if (v == SEQ_START_TOKEN)
2931                 seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
2932                            "rx_queue tr tm->when retrnsmt   uid  timeout "
2933                            "inode ref pointer drops");
2934         else {
2935                 struct udp_iter_state *state = seq->private;
2936 
2937                 udp4_format_sock(v, seq, state->bucket);
2938         }
2939         seq_pad(seq, '\n');
2940         return 0;
2941 }
2942 
2943 const struct seq_operations udp_seq_ops = {
2944         .start          = udp_seq_start,
2945         .next           = udp_seq_next,
2946         .stop           = udp_seq_stop,
2947         .show           = udp4_seq_show,
2948 };
2949 EXPORT_SYMBOL(udp_seq_ops);
2950 
2951 static struct udp_seq_afinfo udp4_seq_afinfo = {
2952         .family         = AF_INET,
2953         .udp_table      = &udp_table,
2954 };
2955 
2956 static int __net_init udp4_proc_init_net(struct net *net)
2957 {
2958         if (!proc_create_net_data("udp", 0444, net->proc_net, &udp_seq_ops,
2959                         sizeof(struct udp_iter_state), &udp4_seq_afinfo))
2960                 return -ENOMEM;
2961         return 0;
2962 }
2963 
2964 static void __net_exit udp4_proc_exit_net(struct net *net)
2965 {
2966         remove_proc_entry("udp", net->proc_net);
2967 }
2968 
2969 static struct pernet_operations udp4_net_ops = {
2970         .init = udp4_proc_init_net,
2971         .exit = udp4_proc_exit_net,
2972 };
2973 
2974 int __init udp4_proc_init(void)
2975 {
2976         return register_pernet_subsys(&udp4_net_ops);
2977 }
2978 
2979 void udp4_proc_exit(void)
2980 {
2981         unregister_pernet_subsys(&udp4_net_ops);
2982 }
2983 #endif /* CONFIG_PROC_FS */
2984 
2985 static __initdata unsigned long uhash_entries;
2986 static int __init set_uhash_entries(char *str)
2987 {
2988         ssize_t ret;
2989 
2990         if (!str)
2991                 return 0;
2992 
2993         ret = kstrtoul(str, 0, &uhash_entries);
2994         if (ret)
2995                 return 0;
2996 
2997         if (uhash_entries && uhash_entries < UDP_HTABLE_SIZE_MIN)
2998                 uhash_entries = UDP_HTABLE_SIZE_MIN;
2999         return 1;
3000 }
3001 __setup("uhash_entries=", set_uhash_entries);
3002 
3003 void __init udp_table_init(struct udp_table *table, const char *name)
3004 {
3005         unsigned int i;
3006 
3007         table->hash = alloc_large_system_hash(name,
3008                                               2 * sizeof(struct udp_hslot),
3009                                               uhash_entries,
3010                                               21, /* one slot per 2 MB */
3011                                               0,
3012                                               &table->log,
3013                                               &table->mask,
3014                                               UDP_HTABLE_SIZE_MIN,
3015                                               64 * 1024);
3016 
3017         table->hash2 = table->hash + (table->mask + 1);
3018         for (i = 0; i <= table->mask; i++) {
3019                 INIT_HLIST_HEAD(&table->hash[i].head);
3020                 table->hash[i].count = 0;
3021                 spin_lock_init(&table->hash[i].lock);
3022         }
3023         for (i = 0; i <= table->mask; i++) {
3024                 INIT_HLIST_HEAD(&table->hash2[i].head);
3025                 table->hash2[i].count = 0;
3026                 spin_lock_init(&table->hash2[i].lock);
3027         }
3028 }
3029 
3030 u32 udp_flow_hashrnd(void)
3031 {
3032         static u32 hashrnd __read_mostly;
3033 
3034         net_get_random_once(&hashrnd, sizeof(hashrnd));
3035 
3036         return hashrnd;
3037 }
3038 EXPORT_SYMBOL(udp_flow_hashrnd);
3039 
3040 static void __udp_sysctl_init(struct net *net)
3041 {
3042         net->ipv4.sysctl_udp_rmem_min = SK_MEM_QUANTUM;
3043         net->ipv4.sysctl_udp_wmem_min = SK_MEM_QUANTUM;
3044 
3045 #ifdef CONFIG_NET_L3_MASTER_DEV
3046         net->ipv4.sysctl_udp_l3mdev_accept = 0;
3047 #endif
3048 }
3049 
3050 static int __net_init udp_sysctl_init(struct net *net)
3051 {
3052         __udp_sysctl_init(net);
3053         return 0;
3054 }
3055 
3056 static struct pernet_operations __net_initdata udp_sysctl_ops = {
3057         .init   = udp_sysctl_init,
3058 };
3059 
3060 void __init udp_init(void)
3061 {
3062         unsigned long limit;
3063         unsigned int i;
3064 
3065         udp_table_init(&udp_table, "UDP");
3066         limit = nr_free_buffer_pages() / 8;
3067         limit = max(limit, 128UL);
3068         sysctl_udp_mem[0] = limit / 4 * 3;
3069         sysctl_udp_mem[1] = limit;
3070         sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2;
3071 
3072         __udp_sysctl_init(&init_net);
3073 
3074         /* 16 spinlocks per cpu */
3075         udp_busylocks_log = ilog2(nr_cpu_ids) + 4;
3076         udp_busylocks = kmalloc(sizeof(spinlock_t) << udp_busylocks_log,
3077                                 GFP_KERNEL);
3078         if (!udp_busylocks)
3079                 panic("UDP: failed to alloc udp_busylocks\n");
3080         for (i = 0; i < (1U << udp_busylocks_log); i++)
3081                 spin_lock_init(udp_busylocks + i);
3082 
3083         if (register_pernet_subsys(&udp_sysctl_ops))
3084                 panic("UDP: failed to init sysctl parameters.\n");
3085 }
3086 

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