1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Definitions for the UDP module.
8 *
9 * Version: @(#)udp.h 1.0.2 05/07/93
10 *
11 * Authors: Ross Biro
12 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 *
14 * Fixes:
15 * Alan Cox : Turned on udp checksums. I don't want to
16 * chase 'memory corruption' bugs that aren't!
17 */
18 #ifndef _UDP_H
19 #define _UDP_H
20
21 #include <linux/list.h>
22 #include <linux/bug.h>
23 #include <net/inet_sock.h>
24 #include <net/gso.h>
25 #include <net/sock.h>
26 #include <net/snmp.h>
27 #include <net/ip.h>
28 #include <linux/ipv6.h>
29 #include <linux/seq_file.h>
30 #include <linux/poll.h>
31 #include <linux/indirect_call_wrapper.h>
32
33 /**
34 * struct udp_skb_cb - UDP(-Lite) private variables
35 *
36 * @header: private variables used by IPv4/IPv6
37 * @cscov: checksum coverage length (UDP-Lite only)
38 * @partial_cov: if set indicates partial csum coverage
39 */
40 struct udp_skb_cb {
41 union {
42 struct inet_skb_parm h4;
43 #if IS_ENABLED(CONFIG_IPV6)
44 struct inet6_skb_parm h6;
45 #endif
46 } header;
47 __u16 cscov;
48 __u8 partial_cov;
49 };
50 #define UDP_SKB_CB(__skb) ((struct udp_skb_cb *)((__skb)->cb))
51
52 /**
53 * struct udp_hslot - UDP hash slot used by udp_table.hash/hash4
54 *
55 * @head: head of list of sockets
56 * @nulls_head: head of list of sockets, only used by hash4
57 * @count: number of sockets in 'head' list
58 * @lock: spinlock protecting changes to head/count
59 */
60 struct udp_hslot {
61 union {
62 struct hlist_head head;
63 /* hash4 uses hlist_nulls to avoid moving wrongly onto another
64 * hlist, because rehash() can happen with lookup().
65 */
66 struct hlist_nulls_head nulls_head;
67 };
68 int count;
69 spinlock_t lock;
70 } __aligned(2 * sizeof(long));
71
72 /**
73 * struct udp_hslot_main - UDP hash slot used by udp_table.hash2
74 *
75 * @hslot: basic hash slot
76 * @hash4_cnt: number of sockets in hslot4 of the same
77 * (local port, local address)
78 */
79 struct udp_hslot_main {
80 struct udp_hslot hslot; /* must be the first member */
81 #if !IS_ENABLED(CONFIG_BASE_SMALL)
82 u32 hash4_cnt;
83 #endif
84 } __aligned(2 * sizeof(long));
85 #define UDP_HSLOT_MAIN(__hslot) ((struct udp_hslot_main *)(__hslot))
86
87 /**
88 * struct udp_table - UDP table
89 *
90 * @hash: hash table, sockets are hashed on (local port)
91 * @hash2: hash table, sockets are hashed on (local port, local address)
92 * @hash4: hash table, connected sockets are hashed on
93 * (local port, local address, remote port, remote address)
94 * @mask: number of slots in hash tables, minus 1
95 * @log: log2(number of slots in hash table)
96 */
97 struct udp_table {
98 struct udp_hslot *hash;
99 struct udp_hslot_main *hash2;
100 #if !IS_ENABLED(CONFIG_BASE_SMALL)
101 struct udp_hslot *hash4;
102 #endif
103 unsigned int mask;
104 unsigned int log;
105 };
106 extern struct udp_table udp_table;
107 void udp_table_init(struct udp_table *, const char *);
udp_hashslot(struct udp_table * table,const struct net * net,unsigned int num)108 static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
109 const struct net *net,
110 unsigned int num)
111 {
112 return &table->hash[udp_hashfn(net, num, table->mask)];
113 }
114
115 /*
116 * For secondary hash, net_hash_mix() is performed before calling
117 * udp_hashslot2(), this explains difference with udp_hashslot()
118 */
udp_hashslot2(struct udp_table * table,unsigned int hash)119 static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
120 unsigned int hash)
121 {
122 return &table->hash2[hash & table->mask].hslot;
123 }
124
125 #if IS_ENABLED(CONFIG_BASE_SMALL)
udp_table_hash4_init(struct udp_table * table)126 static inline void udp_table_hash4_init(struct udp_table *table)
127 {
128 }
129
udp_hashslot4(struct udp_table * table,unsigned int hash)130 static inline struct udp_hslot *udp_hashslot4(struct udp_table *table,
131 unsigned int hash)
132 {
133 BUILD_BUG();
134 return NULL;
135 }
136
udp_hashed4(const struct sock * sk)137 static inline bool udp_hashed4(const struct sock *sk)
138 {
139 return false;
140 }
141
udp_hash4_slot_size(void)142 static inline unsigned int udp_hash4_slot_size(void)
143 {
144 return 0;
145 }
146
udp_has_hash4(const struct udp_hslot * hslot2)147 static inline bool udp_has_hash4(const struct udp_hslot *hslot2)
148 {
149 return false;
150 }
151
udp_hash4_inc(struct udp_hslot * hslot2)152 static inline void udp_hash4_inc(struct udp_hslot *hslot2)
153 {
154 }
155
udp_hash4_dec(struct udp_hslot * hslot2)156 static inline void udp_hash4_dec(struct udp_hslot *hslot2)
157 {
158 }
159 #else /* !CONFIG_BASE_SMALL */
160
161 /* Must be called with table->hash2 initialized */
udp_table_hash4_init(struct udp_table * table)162 static inline void udp_table_hash4_init(struct udp_table *table)
163 {
164 table->hash4 = (void *)(table->hash2 + (table->mask + 1));
165 for (int i = 0; i <= table->mask; i++) {
166 table->hash2[i].hash4_cnt = 0;
167
168 INIT_HLIST_NULLS_HEAD(&table->hash4[i].nulls_head, i);
169 table->hash4[i].count = 0;
170 spin_lock_init(&table->hash4[i].lock);
171 }
172 }
173
udp_hashslot4(struct udp_table * table,unsigned int hash)174 static inline struct udp_hslot *udp_hashslot4(struct udp_table *table,
175 unsigned int hash)
176 {
177 return &table->hash4[hash & table->mask];
178 }
179
udp_hashed4(const struct sock * sk)180 static inline bool udp_hashed4(const struct sock *sk)
181 {
182 return !hlist_nulls_unhashed(&udp_sk(sk)->udp_lrpa_node);
183 }
184
udp_hash4_slot_size(void)185 static inline unsigned int udp_hash4_slot_size(void)
186 {
187 return sizeof(struct udp_hslot);
188 }
189
udp_has_hash4(const struct udp_hslot * hslot2)190 static inline bool udp_has_hash4(const struct udp_hslot *hslot2)
191 {
192 return UDP_HSLOT_MAIN(hslot2)->hash4_cnt;
193 }
194
udp_hash4_inc(struct udp_hslot * hslot2)195 static inline void udp_hash4_inc(struct udp_hslot *hslot2)
196 {
197 UDP_HSLOT_MAIN(hslot2)->hash4_cnt++;
198 }
199
udp_hash4_dec(struct udp_hslot * hslot2)200 static inline void udp_hash4_dec(struct udp_hslot *hslot2)
201 {
202 UDP_HSLOT_MAIN(hslot2)->hash4_cnt--;
203 }
204 #endif /* CONFIG_BASE_SMALL */
205
206 extern struct proto udp_prot;
207
208 extern atomic_long_t udp_memory_allocated;
209 DECLARE_PER_CPU(int, udp_memory_per_cpu_fw_alloc);
210
211 /* sysctl variables for udp */
212 extern long sysctl_udp_mem[3];
213 extern int sysctl_udp_rmem_min;
214 extern int sysctl_udp_wmem_min;
215
216 struct sk_buff;
217
218 /*
219 * Generic checksumming routines for UDP(-Lite) v4 and v6
220 */
__udp_lib_checksum_complete(struct sk_buff * skb)221 static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
222 {
223 return (UDP_SKB_CB(skb)->cscov == skb->len ?
224 __skb_checksum_complete(skb) :
225 __skb_checksum_complete_head(skb, UDP_SKB_CB(skb)->cscov));
226 }
227
udp_lib_checksum_complete(struct sk_buff * skb)228 static inline int udp_lib_checksum_complete(struct sk_buff *skb)
229 {
230 return !skb_csum_unnecessary(skb) &&
231 __udp_lib_checksum_complete(skb);
232 }
233
234 /**
235 * udp_csum_outgoing - compute UDPv4/v6 checksum over fragments
236 * @sk: socket we are writing to
237 * @skb: sk_buff containing the filled-in UDP header
238 * (checksum field must be zeroed out)
239 */
udp_csum_outgoing(struct sock * sk,struct sk_buff * skb)240 static inline __wsum udp_csum_outgoing(struct sock *sk, struct sk_buff *skb)
241 {
242 __wsum csum = csum_partial(skb_transport_header(skb),
243 sizeof(struct udphdr), 0);
244 skb_queue_walk(&sk->sk_write_queue, skb) {
245 csum = csum_add(csum, skb->csum);
246 }
247 return csum;
248 }
249
udp_csum(struct sk_buff * skb)250 static inline __wsum udp_csum(struct sk_buff *skb)
251 {
252 __wsum csum = csum_partial(skb_transport_header(skb),
253 sizeof(struct udphdr), skb->csum);
254
255 for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next) {
256 csum = csum_add(csum, skb->csum);
257 }
258 return csum;
259 }
260
udp_v4_check(int len,__be32 saddr,__be32 daddr,__wsum base)261 static inline __sum16 udp_v4_check(int len, __be32 saddr,
262 __be32 daddr, __wsum base)
263 {
264 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base);
265 }
266
267 void udp_set_csum(bool nocheck, struct sk_buff *skb,
268 __be32 saddr, __be32 daddr, int len);
269
udp_csum_pull_header(struct sk_buff * skb)270 static inline void udp_csum_pull_header(struct sk_buff *skb)
271 {
272 if (!skb->csum_valid && skb->ip_summed == CHECKSUM_NONE)
273 skb->csum = csum_partial(skb->data, sizeof(struct udphdr),
274 skb->csum);
275 skb_pull_rcsum(skb, sizeof(struct udphdr));
276 UDP_SKB_CB(skb)->cscov -= sizeof(struct udphdr);
277 }
278
279 typedef struct sock *(*udp_lookup_t)(const struct sk_buff *skb, __be16 sport,
280 __be16 dport);
281
282 void udp_v6_early_demux(struct sk_buff *skb);
283 INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));
284
285 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
286 netdev_features_t features, bool is_ipv6);
287
udp_lib_init_sock(struct sock * sk)288 static inline void udp_lib_init_sock(struct sock *sk)
289 {
290 struct udp_sock *up = udp_sk(sk);
291
292 skb_queue_head_init(&up->reader_queue);
293 up->forward_threshold = sk->sk_rcvbuf >> 2;
294 set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
295 }
296
297 /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
udp_lib_hash(struct sock * sk)298 static inline int udp_lib_hash(struct sock *sk)
299 {
300 BUG();
301 return 0;
302 }
303
304 void udp_lib_unhash(struct sock *sk);
305 void udp_lib_rehash(struct sock *sk, u16 new_hash, u16 new_hash4);
306 u32 udp_ehashfn(const struct net *net, const __be32 laddr, const __u16 lport,
307 const __be32 faddr, const __be16 fport);
308
udp_lib_close(struct sock * sk,long timeout)309 static inline void udp_lib_close(struct sock *sk, long timeout)
310 {
311 sk_common_release(sk);
312 }
313
314 /* hash4 routines shared between UDPv4/6 */
315 #if IS_ENABLED(CONFIG_BASE_SMALL)
udp_lib_hash4(struct sock * sk,u16 hash)316 static inline void udp_lib_hash4(struct sock *sk, u16 hash)
317 {
318 }
319
udp4_hash4(struct sock * sk)320 static inline void udp4_hash4(struct sock *sk)
321 {
322 }
323 #else /* !CONFIG_BASE_SMALL */
324 void udp_lib_hash4(struct sock *sk, u16 hash);
325 void udp4_hash4(struct sock *sk);
326 #endif /* CONFIG_BASE_SMALL */
327
328 int udp_lib_get_port(struct sock *sk, unsigned short snum,
329 unsigned int hash2_nulladdr);
330
331 u32 udp_flow_hashrnd(void);
332
udp_flow_src_port(struct net * net,struct sk_buff * skb,int min,int max,bool use_eth)333 static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb,
334 int min, int max, bool use_eth)
335 {
336 u32 hash;
337
338 if (min >= max) {
339 /* Use default range */
340 inet_get_local_port_range(net, &min, &max);
341 }
342
343 hash = skb_get_hash(skb);
344 if (unlikely(!hash)) {
345 if (use_eth) {
346 /* Can't find a normal hash, caller has indicated an
347 * Ethernet packet so use that to compute a hash.
348 */
349 hash = jhash(skb->data, 2 * ETH_ALEN,
350 (__force u32) skb->protocol);
351 } else {
352 /* Can't derive any sort of hash for the packet, set
353 * to some consistent random value.
354 */
355 hash = udp_flow_hashrnd();
356 }
357 }
358
359 /* Since this is being sent on the wire obfuscate hash a bit
360 * to minimize possibility that any useful information to an
361 * attacker is leaked. Only upper 16 bits are relevant in the
362 * computation for 16 bit port value.
363 */
364 hash ^= hash << 16;
365
366 return htons((((u64) hash * (max - min)) >> 32) + min);
367 }
368
udp_rqueue_get(struct sock * sk)369 static inline int udp_rqueue_get(struct sock *sk)
370 {
371 return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
372 }
373
udp_sk_bound_dev_eq(const struct net * net,int bound_dev_if,int dif,int sdif)374 static inline bool udp_sk_bound_dev_eq(const struct net *net, int bound_dev_if,
375 int dif, int sdif)
376 {
377 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
378 return inet_bound_dev_eq(!!READ_ONCE(net->ipv4.sysctl_udp_l3mdev_accept),
379 bound_dev_if, dif, sdif);
380 #else
381 return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
382 #endif
383 }
384
385 /* net/ipv4/udp.c */
386 void udp_destruct_common(struct sock *sk);
387 void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
388 int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb);
389 void udp_skb_destructor(struct sock *sk, struct sk_buff *skb);
390 struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags, int *off,
391 int *err);
skb_recv_udp(struct sock * sk,unsigned int flags,int * err)392 static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
393 int *err)
394 {
395 int off = 0;
396
397 return __skb_recv_udp(sk, flags, &off, err);
398 }
399
400 int udp_v4_early_demux(struct sk_buff *skb);
401 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst);
402 int udp_err(struct sk_buff *, u32);
403 int udp_abort(struct sock *sk, int err);
404 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
405 void udp_splice_eof(struct socket *sock);
406 int udp_push_pending_frames(struct sock *sk);
407 void udp_flush_pending_frames(struct sock *sk);
408 int udp_cmsg_send(struct sock *sk, struct msghdr *msg, u16 *gso_size);
409 void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst);
410 int udp_rcv(struct sk_buff *skb);
411 int udp_ioctl(struct sock *sk, int cmd, int *karg);
412 int udp_init_sock(struct sock *sk);
413 int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
414 int __udp_disconnect(struct sock *sk, int flags);
415 int udp_disconnect(struct sock *sk, int flags);
416 __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait);
417 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
418 netdev_features_t features,
419 bool is_ipv6);
420 int udp_lib_getsockopt(struct sock *sk, int level, int optname,
421 char __user *optval, int __user *optlen);
422 int udp_lib_setsockopt(struct sock *sk, int level, int optname,
423 sockptr_t optval, unsigned int optlen,
424 int (*push_pending_frames)(struct sock *));
425 struct sock *udp4_lib_lookup(const struct net *net, __be32 saddr, __be16 sport,
426 __be32 daddr, __be16 dport, int dif);
427 struct sock *__udp4_lib_lookup(const struct net *net, __be32 saddr,
428 __be16 sport,
429 __be32 daddr, __be16 dport, int dif, int sdif,
430 struct udp_table *tbl, struct sk_buff *skb);
431 struct sock *udp4_lib_lookup_skb(const struct sk_buff *skb,
432 __be16 sport, __be16 dport);
433 struct sock *udp6_lib_lookup(const struct net *net,
434 const struct in6_addr *saddr, __be16 sport,
435 const struct in6_addr *daddr, __be16 dport,
436 int dif);
437 struct sock *__udp6_lib_lookup(const struct net *net,
438 const struct in6_addr *saddr, __be16 sport,
439 const struct in6_addr *daddr, __be16 dport,
440 int dif, int sdif, struct udp_table *tbl,
441 struct sk_buff *skb);
442 struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
443 __be16 sport, __be16 dport);
444 int udp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
445
446 /* UDP uses skb->dev_scratch to cache as much information as possible and avoid
447 * possibly multiple cache miss on dequeue()
448 */
449 struct udp_dev_scratch {
450 /* skb->truesize and the stateless bit are embedded in a single field;
451 * do not use a bitfield since the compiler emits better/smaller code
452 * this way
453 */
454 u32 _tsize_state;
455
456 #if BITS_PER_LONG == 64
457 /* len and the bit needed to compute skb_csum_unnecessary
458 * will be on cold cache lines at recvmsg time.
459 * skb->len can be stored on 16 bits since the udp header has been
460 * already validated and pulled.
461 */
462 u16 len;
463 bool is_linear;
464 bool csum_unnecessary;
465 #endif
466 };
467
udp_skb_scratch(struct sk_buff * skb)468 static inline struct udp_dev_scratch *udp_skb_scratch(struct sk_buff *skb)
469 {
470 return (struct udp_dev_scratch *)&skb->dev_scratch;
471 }
472
473 #if BITS_PER_LONG == 64
udp_skb_len(struct sk_buff * skb)474 static inline unsigned int udp_skb_len(struct sk_buff *skb)
475 {
476 return udp_skb_scratch(skb)->len;
477 }
478
udp_skb_csum_unnecessary(struct sk_buff * skb)479 static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
480 {
481 return udp_skb_scratch(skb)->csum_unnecessary;
482 }
483
udp_skb_is_linear(struct sk_buff * skb)484 static inline bool udp_skb_is_linear(struct sk_buff *skb)
485 {
486 return udp_skb_scratch(skb)->is_linear;
487 }
488
489 #else
udp_skb_len(struct sk_buff * skb)490 static inline unsigned int udp_skb_len(struct sk_buff *skb)
491 {
492 return skb->len;
493 }
494
udp_skb_csum_unnecessary(struct sk_buff * skb)495 static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
496 {
497 return skb_csum_unnecessary(skb);
498 }
499
udp_skb_is_linear(struct sk_buff * skb)500 static inline bool udp_skb_is_linear(struct sk_buff *skb)
501 {
502 return !skb_is_nonlinear(skb);
503 }
504 #endif
505
copy_linear_skb(struct sk_buff * skb,int len,int off,struct iov_iter * to)506 static inline int copy_linear_skb(struct sk_buff *skb, int len, int off,
507 struct iov_iter *to)
508 {
509 return copy_to_iter_full(skb->data + off, len, to) ? 0 : -EFAULT;
510 }
511
512 /*
513 * SNMP statistics for UDP and UDP-Lite
514 */
515 #define UDP_INC_STATS(net, field, is_udplite) do { \
516 if (is_udplite) SNMP_INC_STATS((net)->mib.udplite_statistics, field); \
517 else SNMP_INC_STATS((net)->mib.udp_statistics, field); } while(0)
518 #define __UDP_INC_STATS(net, field, is_udplite) do { \
519 if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_statistics, field); \
520 else __SNMP_INC_STATS((net)->mib.udp_statistics, field); } while(0)
521
522 #define __UDP6_INC_STATS(net, field, is_udplite) do { \
523 if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);\
524 else __SNMP_INC_STATS((net)->mib.udp_stats_in6, field); \
525 } while(0)
526 #define UDP6_INC_STATS(net, field, __lite) do { \
527 if (__lite) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field); \
528 else SNMP_INC_STATS((net)->mib.udp_stats_in6, field); \
529 } while(0)
530
531 #if IS_ENABLED(CONFIG_IPV6)
532 #define __UDPX_MIB(sk, ipv4) \
533 ({ \
534 ipv4 ? (IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics : \
535 sock_net(sk)->mib.udp_statistics) : \
536 (IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_stats_in6 : \
537 sock_net(sk)->mib.udp_stats_in6); \
538 })
539 #else
540 #define __UDPX_MIB(sk, ipv4) \
541 ({ \
542 IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics : \
543 sock_net(sk)->mib.udp_statistics; \
544 })
545 #endif
546
547 #define __UDPX_INC_STATS(sk, field) \
548 __SNMP_INC_STATS(__UDPX_MIB(sk, (sk)->sk_family == AF_INET), field)
549
550 #ifdef CONFIG_PROC_FS
551 struct udp_seq_afinfo {
552 sa_family_t family;
553 struct udp_table *udp_table;
554 };
555
556 struct udp_iter_state {
557 struct seq_net_private p;
558 int bucket;
559 };
560
561 void *udp_seq_start(struct seq_file *seq, loff_t *pos);
562 void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
563 void udp_seq_stop(struct seq_file *seq, void *v);
564
565 extern const struct seq_operations udp_seq_ops;
566 extern const struct seq_operations udp6_seq_ops;
567
568 int udp4_proc_init(void);
569 void udp4_proc_exit(void);
570 #endif /* CONFIG_PROC_FS */
571
572 int udpv4_offload_init(void);
573
574 void udp_init(void);
575
576 DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
577 void udp_encap_enable(void);
578 void udp_encap_disable(void);
579 #if IS_ENABLED(CONFIG_IPV6)
580 DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
581 void udpv6_encap_enable(void);
582 #endif
583
udp_rcv_segment(struct sock * sk,struct sk_buff * skb,bool ipv4)584 static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
585 struct sk_buff *skb, bool ipv4)
586 {
587 netdev_features_t features = NETIF_F_SG;
588 struct sk_buff *segs;
589
590 /* Avoid csum recalculation by skb_segment unless userspace explicitly
591 * asks for the final checksum values
592 */
593 if (!inet_get_convert_csum(sk))
594 features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
595
596 /* UDP segmentation expects packets of type CHECKSUM_PARTIAL or
597 * CHECKSUM_NONE in __udp_gso_segment. UDP GRO indeed builds partial
598 * packets in udp_gro_complete_segment. As does UDP GSO, verified by
599 * udp_send_skb. But when those packets are looped in dev_loopback_xmit
600 * their ip_summed CHECKSUM_NONE is changed to CHECKSUM_UNNECESSARY.
601 * Reset in this specific case, where PARTIAL is both correct and
602 * required.
603 */
604 if (skb->pkt_type == PACKET_LOOPBACK)
605 skb->ip_summed = CHECKSUM_PARTIAL;
606
607 /* the GSO CB lays after the UDP one, no need to save and restore any
608 * CB fragment
609 */
610 segs = __skb_gso_segment(skb, features, false);
611 if (IS_ERR_OR_NULL(segs)) {
612 int segs_nr = skb_shinfo(skb)->gso_segs;
613
614 atomic_add(segs_nr, &sk->sk_drops);
615 SNMP_ADD_STATS(__UDPX_MIB(sk, ipv4), UDP_MIB_INERRORS, segs_nr);
616 kfree_skb(skb);
617 return NULL;
618 }
619
620 consume_skb(skb);
621 return segs;
622 }
623
udp_post_segment_fix_csum(struct sk_buff * skb)624 static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
625 {
626 /* UDP-lite can't land here - no GRO */
627 WARN_ON_ONCE(UDP_SKB_CB(skb)->partial_cov);
628
629 /* UDP packets generated with UDP_SEGMENT and traversing:
630 *
631 * UDP tunnel(xmit) -> veth (segmentation) -> veth (gro) -> UDP tunnel (rx)
632 *
633 * can reach an UDP socket with CHECKSUM_NONE, because
634 * __iptunnel_pull_header() converts CHECKSUM_PARTIAL into NONE.
635 * SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST packets with no UDP tunnel will
636 * have a valid checksum, as the GRO engine validates the UDP csum
637 * before the aggregation and nobody strips such info in between.
638 * Instead of adding another check in the tunnel fastpath, we can force
639 * a valid csum after the segmentation.
640 * Additionally fixup the UDP CB.
641 */
642 UDP_SKB_CB(skb)->cscov = skb->len;
643 if (skb->ip_summed == CHECKSUM_NONE && !skb->csum_valid)
644 skb->csum_valid = 1;
645 }
646
647 #ifdef CONFIG_BPF_SYSCALL
648 struct sk_psock;
649 int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
650 #endif
651
652 #endif /* _UDP_H */
653