xref: /openbmc/linux/include/net/sctp/sctp.h (revision 42bc47b3)
1 /* SCTP kernel implementation
2  * (C) Copyright IBM Corp. 2001, 2004
3  * Copyright (c) 1999-2000 Cisco, Inc.
4  * Copyright (c) 1999-2001 Motorola, Inc.
5  * Copyright (c) 2001-2003 Intel Corp.
6  *
7  * This file is part of the SCTP kernel implementation
8  *
9  * The base lksctp header.
10  *
11  * This SCTP implementation is free software;
12  * you can redistribute it and/or modify it under the terms of
13  * the GNU General Public License as published by
14  * the Free Software Foundation; either version 2, or (at your option)
15  * any later version.
16  *
17  * This SCTP implementation is distributed in the hope that it
18  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
19  *                 ************************
20  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
21  * See the GNU General Public License for more details.
22  *
23  * You should have received a copy of the GNU General Public License
24  * along with GNU CC; see the file COPYING.  If not, see
25  * <http://www.gnu.org/licenses/>.
26  *
27  * Please send any bug reports or fixes you make to the
28  * email address(es):
29  *    lksctp developers <linux-sctp@vger.kernel.org>
30  *
31  * Written or modified by:
32  *    La Monte H.P. Yarroll <piggy@acm.org>
33  *    Xingang Guo           <xingang.guo@intel.com>
34  *    Jon Grimm             <jgrimm@us.ibm.com>
35  *    Daisy Chang           <daisyc@us.ibm.com>
36  *    Sridhar Samudrala     <sri@us.ibm.com>
37  *    Ardelle Fan           <ardelle.fan@intel.com>
38  *    Ryan Layer            <rmlayer@us.ibm.com>
39  *    Kevin Gao             <kevin.gao@intel.com>
40  */
41 
42 #ifndef __net_sctp_h__
43 #define __net_sctp_h__
44 
45 /* Header Strategy.
46  *    Start getting some control over the header file depencies:
47  *       includes
48  *       constants
49  *       structs
50  *       prototypes
51  *       macros, externs, and inlines
52  *
53  *   Move test_frame specific items out of the kernel headers
54  *   and into the test frame headers.   This is not perfect in any sense
55  *   and will continue to evolve.
56  */
57 
58 #include <linux/types.h>
59 #include <linux/slab.h>
60 #include <linux/in.h>
61 #include <linux/tty.h>
62 #include <linux/proc_fs.h>
63 #include <linux/spinlock.h>
64 #include <linux/jiffies.h>
65 #include <linux/idr.h>
66 
67 #if IS_ENABLED(CONFIG_IPV6)
68 #include <net/ipv6.h>
69 #include <net/ip6_route.h>
70 #endif
71 
72 #include <linux/uaccess.h>
73 #include <asm/page.h>
74 #include <net/sock.h>
75 #include <net/snmp.h>
76 #include <net/sctp/structs.h>
77 #include <net/sctp/constants.h>
78 
79 #ifdef CONFIG_IP_SCTP_MODULE
80 #define SCTP_PROTOSW_FLAG 0
81 #else /* static! */
82 #define SCTP_PROTOSW_FLAG INET_PROTOSW_PERMANENT
83 #endif
84 
85 /* Round an int up to the next multiple of 4.  */
86 #define SCTP_PAD4(s) (((s)+3)&~3)
87 /* Truncate to the previous multiple of 4.  */
88 #define SCTP_TRUNC4(s) ((s)&~3)
89 
90 /*
91  * Function declarations.
92  */
93 
94 /*
95  * sctp/protocol.c
96  */
97 int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *addr,
98 			      enum sctp_scope, gfp_t gfp, int flags);
99 struct sctp_pf *sctp_get_pf_specific(sa_family_t family);
100 int sctp_register_pf(struct sctp_pf *, sa_family_t);
101 void sctp_addr_wq_mgmt(struct net *, struct sctp_sockaddr_entry *, int);
102 
103 /*
104  * sctp/socket.c
105  */
106 int sctp_inet_connect(struct socket *sock, struct sockaddr *uaddr,
107 		      int addr_len, int flags);
108 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb);
109 int sctp_inet_listen(struct socket *sock, int backlog);
110 void sctp_write_space(struct sock *sk);
111 void sctp_data_ready(struct sock *sk);
112 __poll_t sctp_poll_mask(struct socket *sock, __poll_t events);
113 void sctp_sock_rfree(struct sk_buff *skb);
114 void sctp_copy_sock(struct sock *newsk, struct sock *sk,
115 		    struct sctp_association *asoc);
116 extern struct percpu_counter sctp_sockets_allocated;
117 int sctp_asconf_mgmt(struct sctp_sock *, struct sctp_sockaddr_entry *);
118 struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int, int *);
119 
120 void sctp_transport_walk_start(struct rhashtable_iter *iter);
121 void sctp_transport_walk_stop(struct rhashtable_iter *iter);
122 struct sctp_transport *sctp_transport_get_next(struct net *net,
123 			struct rhashtable_iter *iter);
124 struct sctp_transport *sctp_transport_get_idx(struct net *net,
125 			struct rhashtable_iter *iter, int pos);
126 int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *),
127 				  struct net *net,
128 				  const union sctp_addr *laddr,
129 				  const union sctp_addr *paddr, void *p);
130 int sctp_for_each_transport(int (*cb)(struct sctp_transport *, void *),
131 			    int (*cb_done)(struct sctp_transport *, void *),
132 			    struct net *net, int *pos, void *p);
133 int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), void *p);
134 int sctp_get_sctp_info(struct sock *sk, struct sctp_association *asoc,
135 		       struct sctp_info *info);
136 
137 /*
138  * sctp/primitive.c
139  */
140 int sctp_primitive_ASSOCIATE(struct net *, struct sctp_association *, void *arg);
141 int sctp_primitive_SHUTDOWN(struct net *, struct sctp_association *, void *arg);
142 int sctp_primitive_ABORT(struct net *, struct sctp_association *, void *arg);
143 int sctp_primitive_SEND(struct net *, struct sctp_association *, void *arg);
144 int sctp_primitive_REQUESTHEARTBEAT(struct net *, struct sctp_association *, void *arg);
145 int sctp_primitive_ASCONF(struct net *, struct sctp_association *, void *arg);
146 int sctp_primitive_RECONF(struct net *net, struct sctp_association *asoc,
147 			  void *arg);
148 
149 /*
150  * sctp/input.c
151  */
152 int sctp_rcv(struct sk_buff *skb);
153 void sctp_v4_err(struct sk_buff *skb, u32 info);
154 void sctp_hash_endpoint(struct sctp_endpoint *);
155 void sctp_unhash_endpoint(struct sctp_endpoint *);
156 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *,
157 			     struct sctphdr *, struct sctp_association **,
158 			     struct sctp_transport **);
159 void sctp_err_finish(struct sock *, struct sctp_transport *);
160 void sctp_icmp_frag_needed(struct sock *, struct sctp_association *,
161 			   struct sctp_transport *t, __u32 pmtu);
162 void sctp_icmp_redirect(struct sock *, struct sctp_transport *,
163 			struct sk_buff *);
164 void sctp_icmp_proto_unreachable(struct sock *sk,
165 				 struct sctp_association *asoc,
166 				 struct sctp_transport *t);
167 void sctp_backlog_migrate(struct sctp_association *assoc,
168 			  struct sock *oldsk, struct sock *newsk);
169 int sctp_transport_hashtable_init(void);
170 void sctp_transport_hashtable_destroy(void);
171 int sctp_hash_transport(struct sctp_transport *t);
172 void sctp_unhash_transport(struct sctp_transport *t);
173 struct sctp_transport *sctp_addrs_lookup_transport(
174 				struct net *net,
175 				const union sctp_addr *laddr,
176 				const union sctp_addr *paddr);
177 struct sctp_transport *sctp_epaddr_lookup_transport(
178 				const struct sctp_endpoint *ep,
179 				const union sctp_addr *paddr);
180 
181 /*
182  * sctp/proc.c
183  */
184 int __net_init sctp_proc_init(struct net *net);
185 
186 /*
187  * sctp/offload.c
188  */
189 int sctp_offload_init(void);
190 
191 /*
192  * sctp/stream_sched.c
193  */
194 void sctp_sched_ops_init(void);
195 
196 /*
197  * sctp/stream.c
198  */
199 int sctp_send_reset_streams(struct sctp_association *asoc,
200 			    struct sctp_reset_streams *params);
201 int sctp_send_reset_assoc(struct sctp_association *asoc);
202 int sctp_send_add_streams(struct sctp_association *asoc,
203 			  struct sctp_add_streams *params);
204 
205 /*
206  * Module global variables
207  */
208 
209  /*
210   * sctp/protocol.c
211   */
212 extern struct kmem_cache *sctp_chunk_cachep __read_mostly;
213 extern struct kmem_cache *sctp_bucket_cachep __read_mostly;
214 extern long sysctl_sctp_mem[3];
215 extern int sysctl_sctp_rmem[3];
216 extern int sysctl_sctp_wmem[3];
217 
218 /*
219  *  Section:  Macros, externs, and inlines
220  */
221 
222 /* SCTP SNMP MIB stats handlers */
223 #define SCTP_INC_STATS(net, field)	SNMP_INC_STATS((net)->sctp.sctp_statistics, field)
224 #define __SCTP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->sctp.sctp_statistics, field)
225 #define SCTP_DEC_STATS(net, field)	SNMP_DEC_STATS((net)->sctp.sctp_statistics, field)
226 
227 /* sctp mib definitions */
228 enum {
229 	SCTP_MIB_NUM = 0,
230 	SCTP_MIB_CURRESTAB,			/* CurrEstab */
231 	SCTP_MIB_ACTIVEESTABS,			/* ActiveEstabs */
232 	SCTP_MIB_PASSIVEESTABS,			/* PassiveEstabs */
233 	SCTP_MIB_ABORTEDS,			/* Aborteds */
234 	SCTP_MIB_SHUTDOWNS,			/* Shutdowns */
235 	SCTP_MIB_OUTOFBLUES,			/* OutOfBlues */
236 	SCTP_MIB_CHECKSUMERRORS,		/* ChecksumErrors */
237 	SCTP_MIB_OUTCTRLCHUNKS,			/* OutCtrlChunks */
238 	SCTP_MIB_OUTORDERCHUNKS,		/* OutOrderChunks */
239 	SCTP_MIB_OUTUNORDERCHUNKS,		/* OutUnorderChunks */
240 	SCTP_MIB_INCTRLCHUNKS,			/* InCtrlChunks */
241 	SCTP_MIB_INORDERCHUNKS,			/* InOrderChunks */
242 	SCTP_MIB_INUNORDERCHUNKS,		/* InUnorderChunks */
243 	SCTP_MIB_FRAGUSRMSGS,			/* FragUsrMsgs */
244 	SCTP_MIB_REASMUSRMSGS,			/* ReasmUsrMsgs */
245 	SCTP_MIB_OUTSCTPPACKS,			/* OutSCTPPacks */
246 	SCTP_MIB_INSCTPPACKS,			/* InSCTPPacks */
247 	SCTP_MIB_T1_INIT_EXPIREDS,
248 	SCTP_MIB_T1_COOKIE_EXPIREDS,
249 	SCTP_MIB_T2_SHUTDOWN_EXPIREDS,
250 	SCTP_MIB_T3_RTX_EXPIREDS,
251 	SCTP_MIB_T4_RTO_EXPIREDS,
252 	SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS,
253 	SCTP_MIB_DELAY_SACK_EXPIREDS,
254 	SCTP_MIB_AUTOCLOSE_EXPIREDS,
255 	SCTP_MIB_T1_RETRANSMITS,
256 	SCTP_MIB_T3_RETRANSMITS,
257 	SCTP_MIB_PMTUD_RETRANSMITS,
258 	SCTP_MIB_FAST_RETRANSMITS,
259 	SCTP_MIB_IN_PKT_SOFTIRQ,
260 	SCTP_MIB_IN_PKT_BACKLOG,
261 	SCTP_MIB_IN_PKT_DISCARDS,
262 	SCTP_MIB_IN_DATA_CHUNK_DISCARDS,
263 	__SCTP_MIB_MAX
264 };
265 
266 #define SCTP_MIB_MAX    __SCTP_MIB_MAX
267 struct sctp_mib {
268         unsigned long   mibs[SCTP_MIB_MAX];
269 };
270 
271 /* helper function to track stats about max rto and related transport */
272 static inline void sctp_max_rto(struct sctp_association *asoc,
273 				struct sctp_transport *trans)
274 {
275 	if (asoc->stats.max_obs_rto < (__u64)trans->rto) {
276 		asoc->stats.max_obs_rto = trans->rto;
277 		memset(&asoc->stats.obs_rto_ipaddr, 0,
278 			sizeof(struct sockaddr_storage));
279 		memcpy(&asoc->stats.obs_rto_ipaddr, &trans->ipaddr,
280 			trans->af_specific->sockaddr_len);
281 	}
282 }
283 
284 /*
285  * Macros for keeping a global reference of object allocations.
286  */
287 #ifdef CONFIG_SCTP_DBG_OBJCNT
288 
289 extern atomic_t sctp_dbg_objcnt_sock;
290 extern atomic_t sctp_dbg_objcnt_ep;
291 extern atomic_t sctp_dbg_objcnt_assoc;
292 extern atomic_t sctp_dbg_objcnt_transport;
293 extern atomic_t sctp_dbg_objcnt_chunk;
294 extern atomic_t sctp_dbg_objcnt_bind_addr;
295 extern atomic_t sctp_dbg_objcnt_bind_bucket;
296 extern atomic_t sctp_dbg_objcnt_addr;
297 extern atomic_t sctp_dbg_objcnt_datamsg;
298 extern atomic_t sctp_dbg_objcnt_keys;
299 
300 /* Macros to atomically increment/decrement objcnt counters.  */
301 #define SCTP_DBG_OBJCNT_INC(name) \
302 atomic_inc(&sctp_dbg_objcnt_## name)
303 #define SCTP_DBG_OBJCNT_DEC(name) \
304 atomic_dec(&sctp_dbg_objcnt_## name)
305 #define SCTP_DBG_OBJCNT(name) \
306 atomic_t sctp_dbg_objcnt_## name = ATOMIC_INIT(0)
307 
308 /* Macro to help create new entries in in the global array of
309  * objcnt counters.
310  */
311 #define SCTP_DBG_OBJCNT_ENTRY(name) \
312 {.label= #name, .counter= &sctp_dbg_objcnt_## name}
313 
314 void sctp_dbg_objcnt_init(struct net *);
315 
316 #else
317 
318 #define SCTP_DBG_OBJCNT_INC(name)
319 #define SCTP_DBG_OBJCNT_DEC(name)
320 
321 static inline void sctp_dbg_objcnt_init(struct net *net) { return; }
322 
323 #endif /* CONFIG_SCTP_DBG_OBJCOUNT */
324 
325 #if defined CONFIG_SYSCTL
326 void sctp_sysctl_register(void);
327 void sctp_sysctl_unregister(void);
328 int sctp_sysctl_net_register(struct net *net);
329 void sctp_sysctl_net_unregister(struct net *net);
330 #else
331 static inline void sctp_sysctl_register(void) { return; }
332 static inline void sctp_sysctl_unregister(void) { return; }
333 static inline int sctp_sysctl_net_register(struct net *net) { return 0; }
334 static inline void sctp_sysctl_net_unregister(struct net *net) { return; }
335 #endif
336 
337 /* Size of Supported Address Parameter for 'x' address types. */
338 #define SCTP_SAT_LEN(x) (sizeof(struct sctp_paramhdr) + (x) * sizeof(__u16))
339 
340 #if IS_ENABLED(CONFIG_IPV6)
341 
342 void sctp_v6_pf_init(void);
343 void sctp_v6_pf_exit(void);
344 int sctp_v6_protosw_init(void);
345 void sctp_v6_protosw_exit(void);
346 int sctp_v6_add_protocol(void);
347 void sctp_v6_del_protocol(void);
348 
349 #else /* #ifdef defined(CONFIG_IPV6) */
350 
351 static inline void sctp_v6_pf_init(void) { return; }
352 static inline void sctp_v6_pf_exit(void) { return; }
353 static inline int sctp_v6_protosw_init(void) { return 0; }
354 static inline void sctp_v6_protosw_exit(void) { return; }
355 static inline int sctp_v6_add_protocol(void) { return 0; }
356 static inline void sctp_v6_del_protocol(void) { return; }
357 
358 #endif /* #if defined(CONFIG_IPV6) */
359 
360 
361 /* Map an association to an assoc_id. */
362 static inline sctp_assoc_t sctp_assoc2id(const struct sctp_association *asoc)
363 {
364 	return asoc ? asoc->assoc_id : 0;
365 }
366 
367 static inline enum sctp_sstat_state
368 sctp_assoc_to_state(const struct sctp_association *asoc)
369 {
370 	/* SCTP's uapi always had SCTP_EMPTY(=0) as a dummy state, but we
371 	 * got rid of it in kernel space. Therefore SCTP_CLOSED et al
372 	 * start at =1 in user space, but actually as =0 in kernel space.
373 	 * Now that we can not break user space and SCTP_EMPTY is exposed
374 	 * there, we need to fix it up with an ugly offset not to break
375 	 * applications. :(
376 	 */
377 	return asoc->state + 1;
378 }
379 
380 /* Look up the association by its id.  */
381 struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id);
382 
383 int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp);
384 
385 /* A macro to walk a list of skbs.  */
386 #define sctp_skb_for_each(pos, head, tmp) \
387 	skb_queue_walk_safe(head, pos, tmp)
388 
389 /**
390  *	sctp_list_dequeue - remove from the head of the queue
391  *	@list: list to dequeue from
392  *
393  *	Remove the head of the list. The head item is
394  *	returned or %NULL if the list is empty.
395  */
396 
397 static inline struct list_head *sctp_list_dequeue(struct list_head *list)
398 {
399 	struct list_head *result = NULL;
400 
401 	if (!list_empty(list)) {
402 		result = list->next;
403 		list_del_init(result);
404 	}
405 	return result;
406 }
407 
408 /* SCTP version of skb_set_owner_r.  We need this one because
409  * of the way we have to do receive buffer accounting on bundled
410  * chunks.
411  */
412 static inline void sctp_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
413 {
414 	struct sctp_ulpevent *event = sctp_skb2event(skb);
415 
416 	skb_orphan(skb);
417 	skb->sk = sk;
418 	skb->destructor = sctp_sock_rfree;
419 	atomic_add(event->rmem_len, &sk->sk_rmem_alloc);
420 	/*
421 	 * This mimics the behavior of skb_set_owner_r
422 	 */
423 	sk->sk_forward_alloc -= event->rmem_len;
424 }
425 
426 /* Tests if the list has one and only one entry. */
427 static inline int sctp_list_single_entry(struct list_head *head)
428 {
429 	return (head->next != head) && (head->next == head->prev);
430 }
431 
432 static inline bool sctp_chunk_pending(const struct sctp_chunk *chunk)
433 {
434 	return !list_empty(&chunk->list);
435 }
436 
437 /* Walk through a list of TLV parameters.  Don't trust the
438  * individual parameter lengths and instead depend on
439  * the chunk length to indicate when to stop.  Make sure
440  * there is room for a param header too.
441  */
442 #define sctp_walk_params(pos, chunk, member)\
443 _sctp_walk_params((pos), (chunk), ntohs((chunk)->chunk_hdr.length), member)
444 
445 #define _sctp_walk_params(pos, chunk, end, member)\
446 for (pos.v = chunk->member;\
447      (pos.v + offsetof(struct sctp_paramhdr, length) + sizeof(pos.p->length) <=\
448       (void *)chunk + end) &&\
449      pos.v <= (void *)chunk + end - ntohs(pos.p->length) &&\
450      ntohs(pos.p->length) >= sizeof(struct sctp_paramhdr);\
451      pos.v += SCTP_PAD4(ntohs(pos.p->length)))
452 
453 #define sctp_walk_errors(err, chunk_hdr)\
454 _sctp_walk_errors((err), (chunk_hdr), ntohs((chunk_hdr)->length))
455 
456 #define _sctp_walk_errors(err, chunk_hdr, end)\
457 for (err = (struct sctp_errhdr *)((void *)chunk_hdr + \
458 	    sizeof(struct sctp_chunkhdr));\
459      ((void *)err + offsetof(struct sctp_errhdr, length) + sizeof(err->length) <=\
460       (void *)chunk_hdr + end) &&\
461      (void *)err <= (void *)chunk_hdr + end - ntohs(err->length) &&\
462      ntohs(err->length) >= sizeof(struct sctp_errhdr); \
463      err = (struct sctp_errhdr *)((void *)err + SCTP_PAD4(ntohs(err->length))))
464 
465 #define sctp_walk_fwdtsn(pos, chunk)\
466 _sctp_walk_fwdtsn((pos), (chunk), ntohs((chunk)->chunk_hdr->length) - sizeof(struct sctp_fwdtsn_chunk))
467 
468 #define _sctp_walk_fwdtsn(pos, chunk, end)\
469 for (pos = chunk->subh.fwdtsn_hdr->skip;\
470      (void *)pos <= (void *)chunk->subh.fwdtsn_hdr->skip + end - sizeof(struct sctp_fwdtsn_skip);\
471      pos++)
472 
473 /* External references. */
474 
475 extern struct proto sctp_prot;
476 extern struct proto sctpv6_prot;
477 void sctp_put_port(struct sock *sk);
478 
479 extern struct idr sctp_assocs_id;
480 extern spinlock_t sctp_assocs_id_lock;
481 
482 /* Static inline functions. */
483 
484 /* Convert from an IP version number to an Address Family symbol.  */
485 static inline int ipver2af(__u8 ipver)
486 {
487 	switch (ipver) {
488 	case 4:
489 	        return  AF_INET;
490 	case 6:
491 		return AF_INET6;
492 	default:
493 		return 0;
494 	}
495 }
496 
497 /* Convert from an address parameter type to an address family.  */
498 static inline int param_type2af(__be16 type)
499 {
500 	switch (type) {
501 	case SCTP_PARAM_IPV4_ADDRESS:
502 	        return  AF_INET;
503 	case SCTP_PARAM_IPV6_ADDRESS:
504 		return AF_INET6;
505 	default:
506 		return 0;
507 	}
508 }
509 
510 /* Warning: The following hash functions assume a power of two 'size'. */
511 /* This is the hash function for the SCTP port hash table. */
512 static inline int sctp_phashfn(struct net *net, __u16 lport)
513 {
514 	return (net_hash_mix(net) + lport) & (sctp_port_hashsize - 1);
515 }
516 
517 /* This is the hash function for the endpoint hash table. */
518 static inline int sctp_ep_hashfn(struct net *net, __u16 lport)
519 {
520 	return (net_hash_mix(net) + lport) & (sctp_ep_hashsize - 1);
521 }
522 
523 #define sctp_for_each_hentry(epb, head) \
524 	hlist_for_each_entry(epb, head, node)
525 
526 /* Is a socket of this style? */
527 #define sctp_style(sk, style) __sctp_style((sk), (SCTP_SOCKET_##style))
528 static inline int __sctp_style(const struct sock *sk,
529 			       enum sctp_socket_type style)
530 {
531 	return sctp_sk(sk)->type == style;
532 }
533 
534 /* Is the association in this state? */
535 #define sctp_state(asoc, state) __sctp_state((asoc), (SCTP_STATE_##state))
536 static inline int __sctp_state(const struct sctp_association *asoc,
537 			       enum sctp_state state)
538 {
539 	return asoc->state == state;
540 }
541 
542 /* Is the socket in this state? */
543 #define sctp_sstate(sk, state) __sctp_sstate((sk), (SCTP_SS_##state))
544 static inline int __sctp_sstate(const struct sock *sk,
545 				enum sctp_sock_state state)
546 {
547 	return sk->sk_state == state;
548 }
549 
550 /* Map v4-mapped v6 address back to v4 address */
551 static inline void sctp_v6_map_v4(union sctp_addr *addr)
552 {
553 	addr->v4.sin_family = AF_INET;
554 	addr->v4.sin_port = addr->v6.sin6_port;
555 	addr->v4.sin_addr.s_addr = addr->v6.sin6_addr.s6_addr32[3];
556 }
557 
558 /* Map v4 address to v4-mapped v6 address */
559 static inline void sctp_v4_map_v6(union sctp_addr *addr)
560 {
561 	__be16 port;
562 
563 	port = addr->v4.sin_port;
564 	addr->v6.sin6_addr.s6_addr32[3] = addr->v4.sin_addr.s_addr;
565 	addr->v6.sin6_port = port;
566 	addr->v6.sin6_family = AF_INET6;
567 	addr->v6.sin6_flowinfo = 0;
568 	addr->v6.sin6_scope_id = 0;
569 	addr->v6.sin6_addr.s6_addr32[0] = 0;
570 	addr->v6.sin6_addr.s6_addr32[1] = 0;
571 	addr->v6.sin6_addr.s6_addr32[2] = htonl(0x0000ffff);
572 }
573 
574 /* The cookie is always 0 since this is how it's used in the
575  * pmtu code.
576  */
577 static inline struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t)
578 {
579 	if (t->dst && !dst_check(t->dst, t->dst_cookie))
580 		sctp_transport_dst_release(t);
581 
582 	return t->dst;
583 }
584 
585 /* Calculate max payload size given a MTU, or the total overhead if
586  * given MTU is zero
587  */
588 static inline __u32 sctp_mtu_payload(const struct sctp_sock *sp,
589 				     __u32 mtu, __u32 extra)
590 {
591 	__u32 overhead = sizeof(struct sctphdr) + extra;
592 
593 	if (sp)
594 		overhead += sp->pf->af->net_header_len;
595 	else
596 		overhead += sizeof(struct ipv6hdr);
597 
598 	if (WARN_ON_ONCE(mtu && mtu <= overhead))
599 		mtu = overhead;
600 
601 	return mtu ? mtu - overhead : overhead;
602 }
603 
604 static inline __u32 sctp_dst_mtu(const struct dst_entry *dst)
605 {
606 	return SCTP_TRUNC4(max_t(__u32, dst_mtu(dst),
607 				 SCTP_DEFAULT_MINSEGMENT));
608 }
609 
610 #endif /* __net_sctp_h__ */
611