sctp.h

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