xref: /linux/include/net/sctp/sctp.h (revision 74f1af95820fc2ee580a775a3a17c416db30b38c)
1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* SCTP kernel implementation
3  * (C) Copyright IBM Corp. 2001, 2004
4  * Copyright (c) 1999-2000 Cisco, Inc.
5  * Copyright (c) 1999-2001 Motorola, Inc.
6  * Copyright (c) 2001-2003 Intel Corp.
7  *
8  * This file is part of the SCTP kernel implementation
9  *
10  * The base lksctp header.
11  *
12  * Please send any bug reports or fixes you make to the
13  * email address(es):
14  *    lksctp developers <linux-sctp@vger.kernel.org>
15  *
16  * Written or modified by:
17  *    La Monte H.P. Yarroll <piggy@acm.org>
18  *    Xingang Guo           <xingang.guo@intel.com>
19  *    Jon Grimm             <jgrimm@us.ibm.com>
20  *    Daisy Chang           <daisyc@us.ibm.com>
21  *    Sridhar Samudrala     <sri@us.ibm.com>
22  *    Ardelle Fan           <ardelle.fan@intel.com>
23  *    Ryan Layer            <rmlayer@us.ibm.com>
24  *    Kevin Gao             <kevin.gao@intel.com>
25  */
26 
27 #ifndef __net_sctp_h__
28 #define __net_sctp_h__
29 
30 /* Header Strategy.
31  *    Start getting some control over the header file dependencies:
32  *       includes
33  *       constants
34  *       structs
35  *       prototypes
36  *       macros, externs, and inlines
37  *
38  *   Move test_frame specific items out of the kernel headers
39  *   and into the test frame headers.   This is not perfect in any sense
40  *   and will continue to evolve.
41  */
42 
43 #include <linux/types.h>
44 #include <linux/slab.h>
45 #include <linux/in.h>
46 #include <linux/tty.h>
47 #include <linux/proc_fs.h>
48 #include <linux/spinlock.h>
49 #include <linux/jiffies.h>
50 #include <linux/idr.h>
51 
52 #if IS_ENABLED(CONFIG_IPV6)
53 #include <net/ipv6.h>
54 #include <net/ip6_route.h>
55 #endif
56 
57 #include <linux/uaccess.h>
58 #include <asm/page.h>
59 #include <net/sock.h>
60 #include <net/snmp.h>
61 #include <net/sctp/structs.h>
62 #include <net/sctp/constants.h>
63 
64 #ifdef CONFIG_IP_SCTP_MODULE
65 #define SCTP_PROTOSW_FLAG 0
66 #else /* static! */
67 #define SCTP_PROTOSW_FLAG INET_PROTOSW_PERMANENT
68 #endif
69 
70 /*
71  * Function declarations.
72  */
73 
74 /*
75  * sctp/protocol.c
76  */
77 int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *addr,
78 			      enum sctp_scope, gfp_t gfp, int flags);
79 struct sctp_pf *sctp_get_pf_specific(sa_family_t family);
80 int sctp_register_pf(struct sctp_pf *, sa_family_t);
81 void sctp_addr_wq_mgmt(struct net *, struct sctp_sockaddr_entry *, int);
82 int sctp_udp_sock_start(struct net *net);
83 void sctp_udp_sock_stop(struct net *net);
84 
85 /*
86  * sctp/socket.c
87  */
88 int sctp_inet_connect(struct socket *sock, struct sockaddr *uaddr,
89 		      int addr_len, int flags);
90 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb);
91 int sctp_inet_listen(struct socket *sock, int backlog);
92 void sctp_write_space(struct sock *sk);
93 void sctp_data_ready(struct sock *sk);
94 __poll_t sctp_poll(struct file *file, struct socket *sock,
95 		poll_table *wait);
96 void sctp_sock_rfree(struct sk_buff *skb);
97 void sctp_copy_sock(struct sock *newsk, struct sock *sk,
98 		    struct sctp_association *asoc);
99 extern struct percpu_counter sctp_sockets_allocated;
100 int sctp_asconf_mgmt(struct sctp_sock *, struct sctp_sockaddr_entry *);
101 struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int *);
102 
103 typedef int (*sctp_callback_t)(struct sctp_endpoint *, struct sctp_transport *, void *);
104 void sctp_transport_walk_start(struct rhashtable_iter *iter);
105 void sctp_transport_walk_stop(struct rhashtable_iter *iter);
106 struct sctp_transport *sctp_transport_get_next(struct net *net,
107 			struct rhashtable_iter *iter);
108 struct sctp_transport *sctp_transport_get_idx(struct net *net,
109 			struct rhashtable_iter *iter, int pos);
110 int sctp_transport_lookup_process(sctp_callback_t cb, struct net *net,
111 				  const union sctp_addr *laddr,
112 				  const union sctp_addr *paddr, void *p, int dif);
113 int sctp_transport_traverse_process(sctp_callback_t cb, sctp_callback_t cb_done,
114 				    struct net *net, int *pos, void *p);
115 int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), void *p);
116 int sctp_get_sctp_info(struct sock *sk, struct sctp_association *asoc,
117 		       struct sctp_info *info);
118 
119 /*
120  * sctp/primitive.c
121  */
122 int sctp_primitive_ASSOCIATE(struct net *, struct sctp_association *, void *arg);
123 int sctp_primitive_SHUTDOWN(struct net *, struct sctp_association *, void *arg);
124 int sctp_primitive_ABORT(struct net *, struct sctp_association *, void *arg);
125 int sctp_primitive_SEND(struct net *, struct sctp_association *, void *arg);
126 int sctp_primitive_REQUESTHEARTBEAT(struct net *, struct sctp_association *, void *arg);
127 int sctp_primitive_ASCONF(struct net *, struct sctp_association *, void *arg);
128 int sctp_primitive_RECONF(struct net *net, struct sctp_association *asoc,
129 			  void *arg);
130 
131 /*
132  * sctp/input.c
133  */
134 int sctp_rcv(struct sk_buff *skb);
135 int sctp_v4_err(struct sk_buff *skb, u32 info);
136 int sctp_hash_endpoint(struct sctp_endpoint *ep);
137 void sctp_unhash_endpoint(struct sctp_endpoint *);
138 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *,
139 			     struct sctphdr *, struct sctp_association **,
140 			     struct sctp_transport **);
141 void sctp_err_finish(struct sock *, struct sctp_transport *);
142 int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb);
143 int sctp_udp_v6_err(struct sock *sk, struct sk_buff *skb);
144 void sctp_icmp_frag_needed(struct sock *, struct sctp_association *,
145 			   struct sctp_transport *t, __u32 pmtu);
146 void sctp_icmp_redirect(struct sock *, struct sctp_transport *,
147 			struct sk_buff *);
148 void sctp_icmp_proto_unreachable(struct sock *sk,
149 				 struct sctp_association *asoc,
150 				 struct sctp_transport *t);
151 int sctp_transport_hashtable_init(void);
152 void sctp_transport_hashtable_destroy(void);
153 int sctp_hash_transport(struct sctp_transport *t);
154 void sctp_unhash_transport(struct sctp_transport *t);
155 struct sctp_transport *sctp_addrs_lookup_transport(
156 				struct net *net,
157 				const union sctp_addr *laddr,
158 				const union sctp_addr *paddr,
159 				int dif, int sdif);
160 struct sctp_transport *sctp_epaddr_lookup_transport(
161 				const struct sctp_endpoint *ep,
162 				const union sctp_addr *paddr);
163 bool sctp_sk_bound_dev_eq(struct net *net, int bound_dev_if, int dif, int sdif);
164 
165 /*
166  * sctp/proc.c
167  */
168 int __net_init sctp_proc_init(struct net *net);
169 
170 /*
171  * sctp/offload.c
172  */
173 int sctp_offload_init(void);
174 
175 /*
176  * sctp/stream_sched.c
177  */
178 void sctp_sched_ops_init(void);
179 
180 /*
181  * sctp/stream.c
182  */
183 int sctp_send_reset_streams(struct sctp_association *asoc,
184 			    struct sctp_reset_streams *params);
185 int sctp_send_reset_assoc(struct sctp_association *asoc);
186 int sctp_send_add_streams(struct sctp_association *asoc,
187 			  struct sctp_add_streams *params);
188 
189 /*
190  * Module global variables
191  */
192 
193  /*
194   * sctp/protocol.c
195   */
196 extern struct kmem_cache *sctp_chunk_cachep __read_mostly;
197 extern struct kmem_cache *sctp_bucket_cachep __read_mostly;
198 extern long sysctl_sctp_mem[3];
199 extern int sysctl_sctp_rmem[3];
200 extern int sysctl_sctp_wmem[3];
201 
202 /*
203  *  Section:  Macros, externs, and inlines
204  */
205 
206 /* SCTP SNMP MIB stats handlers */
207 #define SCTP_INC_STATS(net, field)	SNMP_INC_STATS((net)->sctp.sctp_statistics, field)
208 #define __SCTP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->sctp.sctp_statistics, field)
209 #define SCTP_DEC_STATS(net, field)	SNMP_DEC_STATS((net)->sctp.sctp_statistics, field)
210 
211 /* sctp mib definitions */
212 enum {
213 	SCTP_MIB_NUM = 0,
214 	SCTP_MIB_CURRESTAB,			/* CurrEstab */
215 	SCTP_MIB_ACTIVEESTABS,			/* ActiveEstabs */
216 	SCTP_MIB_PASSIVEESTABS,			/* PassiveEstabs */
217 	SCTP_MIB_ABORTEDS,			/* Aborteds */
218 	SCTP_MIB_SHUTDOWNS,			/* Shutdowns */
219 	SCTP_MIB_OUTOFBLUES,			/* OutOfBlues */
220 	SCTP_MIB_CHECKSUMERRORS,		/* ChecksumErrors */
221 	SCTP_MIB_OUTCTRLCHUNKS,			/* OutCtrlChunks */
222 	SCTP_MIB_OUTORDERCHUNKS,		/* OutOrderChunks */
223 	SCTP_MIB_OUTUNORDERCHUNKS,		/* OutUnorderChunks */
224 	SCTP_MIB_INCTRLCHUNKS,			/* InCtrlChunks */
225 	SCTP_MIB_INORDERCHUNKS,			/* InOrderChunks */
226 	SCTP_MIB_INUNORDERCHUNKS,		/* InUnorderChunks */
227 	SCTP_MIB_FRAGUSRMSGS,			/* FragUsrMsgs */
228 	SCTP_MIB_REASMUSRMSGS,			/* ReasmUsrMsgs */
229 	SCTP_MIB_OUTSCTPPACKS,			/* OutSCTPPacks */
230 	SCTP_MIB_INSCTPPACKS,			/* InSCTPPacks */
231 	SCTP_MIB_T1_INIT_EXPIREDS,
232 	SCTP_MIB_T1_COOKIE_EXPIREDS,
233 	SCTP_MIB_T2_SHUTDOWN_EXPIREDS,
234 	SCTP_MIB_T3_RTX_EXPIREDS,
235 	SCTP_MIB_T4_RTO_EXPIREDS,
236 	SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS,
237 	SCTP_MIB_DELAY_SACK_EXPIREDS,
238 	SCTP_MIB_AUTOCLOSE_EXPIREDS,
239 	SCTP_MIB_T1_RETRANSMITS,
240 	SCTP_MIB_T3_RETRANSMITS,
241 	SCTP_MIB_PMTUD_RETRANSMITS,
242 	SCTP_MIB_FAST_RETRANSMITS,
243 	SCTP_MIB_IN_PKT_SOFTIRQ,
244 	SCTP_MIB_IN_PKT_BACKLOG,
245 	SCTP_MIB_IN_PKT_DISCARDS,
246 	SCTP_MIB_IN_DATA_CHUNK_DISCARDS,
247 	__SCTP_MIB_MAX
248 };
249 
250 #define SCTP_MIB_MAX    __SCTP_MIB_MAX
251 struct sctp_mib {
252         unsigned long   mibs[SCTP_MIB_MAX];
253 };
254 
255 /* helper function to track stats about max rto and related transport */
256 static inline void sctp_max_rto(struct sctp_association *asoc,
257 				struct sctp_transport *trans)
258 {
259 	if (asoc->stats.max_obs_rto < (__u64)trans->rto) {
260 		asoc->stats.max_obs_rto = trans->rto;
261 		memset(&asoc->stats.obs_rto_ipaddr, 0,
262 			sizeof(struct sockaddr_storage));
263 		memcpy(&asoc->stats.obs_rto_ipaddr, &trans->ipaddr,
264 			trans->af_specific->sockaddr_len);
265 	}
266 }
267 
268 /*
269  * Macros for keeping a global reference of object allocations.
270  */
271 #ifdef CONFIG_SCTP_DBG_OBJCNT
272 
273 extern atomic_t sctp_dbg_objcnt_sock;
274 extern atomic_t sctp_dbg_objcnt_ep;
275 extern atomic_t sctp_dbg_objcnt_assoc;
276 extern atomic_t sctp_dbg_objcnt_transport;
277 extern atomic_t sctp_dbg_objcnt_chunk;
278 extern atomic_t sctp_dbg_objcnt_bind_addr;
279 extern atomic_t sctp_dbg_objcnt_bind_bucket;
280 extern atomic_t sctp_dbg_objcnt_addr;
281 extern atomic_t sctp_dbg_objcnt_datamsg;
282 extern atomic_t sctp_dbg_objcnt_keys;
283 
284 /* Macros to atomically increment/decrement objcnt counters.  */
285 #define SCTP_DBG_OBJCNT_INC(name) \
286 atomic_inc(&sctp_dbg_objcnt_## name)
287 #define SCTP_DBG_OBJCNT_DEC(name) \
288 atomic_dec(&sctp_dbg_objcnt_## name)
289 #define SCTP_DBG_OBJCNT(name) \
290 atomic_t sctp_dbg_objcnt_## name = ATOMIC_INIT(0)
291 
292 /* Macro to help create new entries in the global array of
293  * objcnt counters.
294  */
295 #define SCTP_DBG_OBJCNT_ENTRY(name) \
296 {.label= #name, .counter= &sctp_dbg_objcnt_## name}
297 
298 void sctp_dbg_objcnt_init(struct net *);
299 
300 #else
301 
302 #define SCTP_DBG_OBJCNT_INC(name)
303 #define SCTP_DBG_OBJCNT_DEC(name)
304 
305 static inline void sctp_dbg_objcnt_init(struct net *net) { return; }
306 
307 #endif /* CONFIG_SCTP_DBG_OBJCOUNT */
308 
309 #if defined CONFIG_SYSCTL
310 void sctp_sysctl_register(void);
311 void sctp_sysctl_unregister(void);
312 int sctp_sysctl_net_register(struct net *net);
313 void sctp_sysctl_net_unregister(struct net *net);
314 #else
315 static inline void sctp_sysctl_register(void) { return; }
316 static inline void sctp_sysctl_unregister(void) { return; }
317 static inline int sctp_sysctl_net_register(struct net *net) { return 0; }
318 static inline void sctp_sysctl_net_unregister(struct net *net) { return; }
319 #endif
320 
321 /* Size of Supported Address Parameter for 'x' address types. */
322 #define SCTP_SAT_LEN(x) (sizeof(struct sctp_paramhdr) + (x) * sizeof(__u16))
323 
324 #if IS_ENABLED(CONFIG_IPV6)
325 
326 void sctp_v6_pf_init(void);
327 void sctp_v6_pf_exit(void);
328 int sctp_v6_protosw_init(void);
329 void sctp_v6_protosw_exit(void);
330 int sctp_v6_add_protocol(void);
331 void sctp_v6_del_protocol(void);
332 
333 #else /* #ifdef defined(CONFIG_IPV6) */
334 
335 static inline void sctp_v6_pf_init(void) { return; }
336 static inline void sctp_v6_pf_exit(void) { return; }
337 static inline int sctp_v6_protosw_init(void) { return 0; }
338 static inline void sctp_v6_protosw_exit(void) { return; }
339 static inline int sctp_v6_add_protocol(void) { return 0; }
340 static inline void sctp_v6_del_protocol(void) { return; }
341 
342 #endif /* #if defined(CONFIG_IPV6) */
343 
344 
345 /* Map an association to an assoc_id. */
346 static inline sctp_assoc_t sctp_assoc2id(const struct sctp_association *asoc)
347 {
348 	return asoc ? asoc->assoc_id : 0;
349 }
350 
351 static inline enum sctp_sstat_state
352 sctp_assoc_to_state(const struct sctp_association *asoc)
353 {
354 	/* SCTP's uapi always had SCTP_EMPTY(=0) as a dummy state, but we
355 	 * got rid of it in kernel space. Therefore SCTP_CLOSED et al
356 	 * start at =1 in user space, but actually as =0 in kernel space.
357 	 * Now that we can not break user space and SCTP_EMPTY is exposed
358 	 * there, we need to fix it up with an ugly offset not to break
359 	 * applications. :(
360 	 */
361 	return asoc->state + 1;
362 }
363 
364 /* Look up the association by its id.  */
365 struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id);
366 
367 /* A macro to walk a list of skbs.  */
368 #define sctp_skb_for_each(pos, head, tmp) \
369 	skb_queue_walk_safe(head, pos, tmp)
370 
371 /**
372  *	sctp_list_dequeue - remove from the head of the queue
373  *	@list: list to dequeue from
374  *
375  *	Remove the head of the list. The head item is
376  *	returned or %NULL if the list is empty.
377  */
378 
379 static inline struct list_head *sctp_list_dequeue(struct list_head *list)
380 {
381 	struct list_head *result = NULL;
382 
383 	if (!list_empty(list)) {
384 		result = list->next;
385 		list_del_init(result);
386 	}
387 	return result;
388 }
389 
390 /* SCTP version of skb_set_owner_r.  We need this one because
391  * of the way we have to do receive buffer accounting on bundled
392  * chunks.
393  */
394 static inline void sctp_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
395 {
396 	struct sctp_ulpevent *event = sctp_skb2event(skb);
397 
398 	skb_orphan(skb);
399 	skb->sk = sk;
400 	skb->destructor = sctp_sock_rfree;
401 	atomic_add(event->rmem_len, &sk->sk_rmem_alloc);
402 	/*
403 	 * This mimics the behavior of skb_set_owner_r
404 	 */
405 	sk_mem_charge(sk, event->rmem_len);
406 }
407 
408 /* Tests if the list has one and only one entry. */
409 static inline int sctp_list_single_entry(struct list_head *head)
410 {
411 	return list_is_singular(head);
412 }
413 
414 static inline bool sctp_chunk_pending(const struct sctp_chunk *chunk)
415 {
416 	return !list_empty(&chunk->list);
417 }
418 
419 /* Walk through a list of TLV parameters.  Don't trust the
420  * individual parameter lengths and instead depend on
421  * the chunk length to indicate when to stop.  Make sure
422  * there is room for a param header too.
423  */
424 #define sctp_walk_params(pos, chunk)\
425 _sctp_walk_params((pos), (chunk), ntohs((chunk)->chunk_hdr.length))
426 
427 #define _sctp_walk_params(pos, chunk, end)\
428 for (pos.v = (u8 *)(chunk + 1);\
429      (pos.v + offsetof(struct sctp_paramhdr, length) + sizeof(pos.p->length) <=\
430       (void *)chunk + end) &&\
431      pos.v <= (void *)chunk + end - ntohs(pos.p->length) &&\
432      ntohs(pos.p->length) >= sizeof(struct sctp_paramhdr);\
433      pos.v += SCTP_PAD4(ntohs(pos.p->length)))
434 
435 #define sctp_walk_errors(err, chunk_hdr)\
436 _sctp_walk_errors((err), (chunk_hdr), ntohs((chunk_hdr)->length))
437 
438 #define _sctp_walk_errors(err, chunk_hdr, end)\
439 for (err = (struct sctp_errhdr *)((void *)chunk_hdr + \
440 	    sizeof(struct sctp_chunkhdr));\
441      ((void *)err + offsetof(struct sctp_errhdr, length) + sizeof(err->length) <=\
442       (void *)chunk_hdr + end) &&\
443      (void *)err <= (void *)chunk_hdr + end - ntohs(err->length) &&\
444      ntohs(err->length) >= sizeof(struct sctp_errhdr); \
445      err = (struct sctp_errhdr *)((void *)err + SCTP_PAD4(ntohs(err->length))))
446 
447 #define sctp_walk_fwdtsn(pos, chunk)\
448 _sctp_walk_fwdtsn((pos), (chunk), ntohs((chunk)->chunk_hdr->length) - sizeof(struct sctp_fwdtsn_chunk))
449 
450 #define _sctp_walk_fwdtsn(pos, chunk, end)\
451 for (pos = (void *)(chunk->subh.fwdtsn_hdr + 1);\
452      (void *)pos <= (void *)(chunk->subh.fwdtsn_hdr + 1) + end - sizeof(struct sctp_fwdtsn_skip);\
453      pos++)
454 
455 /* External references. */
456 
457 extern struct proto sctp_prot;
458 extern struct proto sctpv6_prot;
459 void sctp_put_port(struct sock *sk);
460 
461 extern struct idr sctp_assocs_id;
462 extern spinlock_t sctp_assocs_id_lock;
463 
464 /* Static inline functions. */
465 
466 /* Convert from an IP version number to an Address Family symbol.  */
467 static inline int ipver2af(__u8 ipver)
468 {
469 	switch (ipver) {
470 	case 4:
471 	        return  AF_INET;
472 	case 6:
473 		return AF_INET6;
474 	default:
475 		return 0;
476 	}
477 }
478 
479 /* Convert from an address parameter type to an address family.  */
480 static inline int param_type2af(__be16 type)
481 {
482 	switch (type) {
483 	case SCTP_PARAM_IPV4_ADDRESS:
484 	        return  AF_INET;
485 	case SCTP_PARAM_IPV6_ADDRESS:
486 		return AF_INET6;
487 	default:
488 		return 0;
489 	}
490 }
491 
492 /* Warning: The following hash functions assume a power of two 'size'. */
493 /* This is the hash function for the SCTP port hash table. */
494 static inline int sctp_phashfn(struct net *net, __u16 lport)
495 {
496 	return (net_hash_mix(net) + lport) & (sctp_port_hashsize - 1);
497 }
498 
499 /* This is the hash function for the endpoint hash table. */
500 static inline int sctp_ep_hashfn(struct net *net, __u16 lport)
501 {
502 	return (net_hash_mix(net) + lport) & (sctp_ep_hashsize - 1);
503 }
504 
505 #define sctp_for_each_hentry(ep, head) \
506 	hlist_for_each_entry(ep, head, node)
507 
508 /* Is a socket of this style? */
509 #define sctp_style(sk, style) __sctp_style((sk), (SCTP_SOCKET_##style))
510 static inline int __sctp_style(const struct sock *sk,
511 			       enum sctp_socket_type style)
512 {
513 	return sctp_sk(sk)->type == style;
514 }
515 
516 /* Is the association in this state? */
517 #define sctp_state(asoc, state) __sctp_state((asoc), (SCTP_STATE_##state))
518 static inline int __sctp_state(const struct sctp_association *asoc,
519 			       enum sctp_state state)
520 {
521 	return asoc->state == state;
522 }
523 
524 /* Is the socket in this state? */
525 #define sctp_sstate(sk, state) __sctp_sstate((sk), (SCTP_SS_##state))
526 static inline int __sctp_sstate(const struct sock *sk,
527 				enum sctp_sock_state state)
528 {
529 	return sk->sk_state == state;
530 }
531 
532 /* Map v4-mapped v6 address back to v4 address */
533 static inline void sctp_v6_map_v4(union sctp_addr *addr)
534 {
535 	addr->v4.sin_family = AF_INET;
536 	addr->v4.sin_port = addr->v6.sin6_port;
537 	addr->v4.sin_addr.s_addr = addr->v6.sin6_addr.s6_addr32[3];
538 }
539 
540 /* Map v4 address to v4-mapped v6 address */
541 static inline void sctp_v4_map_v6(union sctp_addr *addr)
542 {
543 	__be16 port;
544 
545 	port = addr->v4.sin_port;
546 	addr->v6.sin6_addr.s6_addr32[3] = addr->v4.sin_addr.s_addr;
547 	addr->v6.sin6_port = port;
548 	addr->v6.sin6_family = AF_INET6;
549 	addr->v6.sin6_flowinfo = 0;
550 	addr->v6.sin6_scope_id = 0;
551 	addr->v6.sin6_addr.s6_addr32[0] = 0;
552 	addr->v6.sin6_addr.s6_addr32[1] = 0;
553 	addr->v6.sin6_addr.s6_addr32[2] = htonl(0x0000ffff);
554 }
555 
556 /* The cookie is always 0 since this is how it's used in the
557  * pmtu code.
558  */
559 static inline struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t)
560 {
561 	if (t->dst && !dst_check(t->dst, t->dst_cookie))
562 		sctp_transport_dst_release(t);
563 
564 	return t->dst;
565 }
566 
567 /* Calculate max payload size given a MTU, or the total overhead if
568  * given MTU is zero
569  */
570 static inline __u32 __sctp_mtu_payload(const struct sctp_sock *sp,
571 				       const struct sctp_transport *t,
572 				       __u32 mtu, __u32 extra)
573 {
574 	__u32 overhead = sizeof(struct sctphdr) + extra;
575 
576 	if (sp) {
577 		overhead += sp->pf->af->net_header_len;
578 		if (sp->udp_port && (!t || t->encap_port))
579 			overhead += sizeof(struct udphdr);
580 	} else {
581 		overhead += sizeof(struct ipv6hdr);
582 	}
583 
584 	if (WARN_ON_ONCE(mtu && mtu <= overhead))
585 		mtu = overhead;
586 
587 	return mtu ? mtu - overhead : overhead;
588 }
589 
590 static inline __u32 sctp_mtu_payload(const struct sctp_sock *sp,
591 				     __u32 mtu, __u32 extra)
592 {
593 	return __sctp_mtu_payload(sp, NULL, mtu, extra);
594 }
595 
596 static inline __u32 sctp_dst_mtu(const struct dst_entry *dst)
597 {
598 	return SCTP_TRUNC4(max_t(__u32, dst_mtu(dst),
599 				 SCTP_DEFAULT_MINSEGMENT));
600 }
601 
602 static inline bool sctp_transport_pmtu_check(struct sctp_transport *t)
603 {
604 	__u32 pmtu = sctp_dst_mtu(t->dst);
605 
606 	if (t->pathmtu == pmtu)
607 		return true;
608 
609 	t->pathmtu = pmtu;
610 
611 	return false;
612 }
613 
614 static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize)
615 {
616 	return sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, datasize);
617 }
618 
619 static inline int sctp_transport_pl_hlen(struct sctp_transport *t)
620 {
621 	return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0) -
622 	       sizeof(struct sctphdr);
623 }
624 
625 static inline void sctp_transport_pl_reset(struct sctp_transport *t)
626 {
627 	if (t->probe_interval && (t->param_flags & SPP_PMTUD_ENABLE) &&
628 	    (t->state == SCTP_ACTIVE || t->state == SCTP_UNKNOWN)) {
629 		if (t->pl.state == SCTP_PL_DISABLED) {
630 			t->pl.state = SCTP_PL_BASE;
631 			t->pl.pmtu = SCTP_BASE_PLPMTU;
632 			t->pl.probe_size = SCTP_BASE_PLPMTU;
633 			sctp_transport_reset_probe_timer(t);
634 		}
635 	} else {
636 		if (t->pl.state != SCTP_PL_DISABLED) {
637 			if (timer_delete(&t->probe_timer))
638 				sctp_transport_put(t);
639 			t->pl.state = SCTP_PL_DISABLED;
640 		}
641 	}
642 }
643 
644 static inline void sctp_transport_pl_update(struct sctp_transport *t)
645 {
646 	if (t->pl.state == SCTP_PL_DISABLED)
647 		return;
648 
649 	t->pl.state = SCTP_PL_BASE;
650 	t->pl.pmtu = SCTP_BASE_PLPMTU;
651 	t->pl.probe_size = SCTP_BASE_PLPMTU;
652 	sctp_transport_reset_probe_timer(t);
653 }
654 
655 static inline bool sctp_transport_pl_enabled(struct sctp_transport *t)
656 {
657 	return t->pl.state != SCTP_PL_DISABLED;
658 }
659 
660 static inline bool sctp_newsk_ready(const struct sock *sk)
661 {
662 	return sock_flag(sk, SOCK_DEAD) || sk->sk_socket;
663 }
664 
665 static inline void sctp_sock_set_nodelay(struct sock *sk)
666 {
667 	lock_sock(sk);
668 	sctp_sk(sk)->nodelay = true;
669 	release_sock(sk);
670 }
671 
672 #endif /* __net_sctp_h__ */
673