Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 679 insertions, 0 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
new file mode 100644
index 000000000..a04999ee9
--- /dev/null
+++ b/include/net/sctp/sctp.h
@@ -0,0 +1,679 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* SCTP kernel implementation
+ * (C) Copyright IBM Corp. 2001, 2004
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 Intel Corp.
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * The base lksctp header.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    La Monte H.P. Yarroll <piggy@acm.org>
+ *    Xingang Guo           <xingang.guo@intel.com>
+ *    Jon Grimm             <jgrimm@us.ibm.com>
+ *    Daisy Chang           <daisyc@us.ibm.com>
+ *    Sridhar Samudrala     <sri@us.ibm.com>
+ *    Ardelle Fan           <ardelle.fan@intel.com>
+ *    Ryan Layer            <rmlayer@us.ibm.com>
+ *    Kevin Gao             <kevin.gao@intel.com> 
+ */
+
+#ifndef __net_sctp_h__
+#define __net_sctp_h__
+
+/* Header Strategy.
+ *    Start getting some control over the header file depencies:
+ *       includes
+ *       constants
+ *       structs
+ *       prototypes
+ *       macros, externs, and inlines
+ *
+ *   Move test_frame specific items out of the kernel headers
+ *   and into the test frame headers.   This is not perfect in any sense
+ *   and will continue to evolve.
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/in.h>
+#include <linux/tty.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/idr.h>
+
+#if IS_ENABLED(CONFIG_IPV6)
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#endif
+
+#include <linux/uaccess.h>
+#include <asm/page.h>
+#include <net/sock.h>
+#include <net/snmp.h>
+#include <net/sctp/structs.h>
+#include <net/sctp/constants.h>
+
+#ifdef CONFIG_IP_SCTP_MODULE
+#define SCTP_PROTOSW_FLAG 0
+#else /* static! */
+#define SCTP_PROTOSW_FLAG INET_PROTOSW_PERMANENT
+#endif
+
+/* Round an int up to the next multiple of 4.  */
+#define SCTP_PAD4(s) (((s)+3)&~3)
+/* Truncate to the previous multiple of 4.  */
+#define SCTP_TRUNC4(s) ((s)&~3)
+
+/*
+ * Function declarations.
+ */
+
+/*
+ * sctp/protocol.c
+ */
+int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *addr,
+			      enum sctp_scope, gfp_t gfp, int flags);
+struct sctp_pf *sctp_get_pf_specific(sa_family_t family);
+int sctp_register_pf(struct sctp_pf *, sa_family_t);
+void sctp_addr_wq_mgmt(struct net *, struct sctp_sockaddr_entry *, int);
+int sctp_udp_sock_start(struct net *net);
+void sctp_udp_sock_stop(struct net *net);
+
+/*
+ * sctp/socket.c
+ */
+int sctp_inet_connect(struct socket *sock, struct sockaddr *uaddr,
+		      int addr_len, int flags);
+int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+int sctp_inet_listen(struct socket *sock, int backlog);
+void sctp_write_space(struct sock *sk);
+void sctp_data_ready(struct sock *sk);
+__poll_t sctp_poll(struct file *file, struct socket *sock,
+		poll_table *wait);
+void sctp_sock_rfree(struct sk_buff *skb);
+void sctp_copy_sock(struct sock *newsk, struct sock *sk,
+		    struct sctp_association *asoc);
+extern struct percpu_counter sctp_sockets_allocated;
+int sctp_asconf_mgmt(struct sctp_sock *, struct sctp_sockaddr_entry *);
+struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int *);
+
+typedef int (*sctp_callback_t)(struct sctp_endpoint *, struct sctp_transport *, void *);
+void sctp_transport_walk_start(struct rhashtable_iter *iter);
+void sctp_transport_walk_stop(struct rhashtable_iter *iter);
+struct sctp_transport *sctp_transport_get_next(struct net *net,
+			struct rhashtable_iter *iter);
+struct sctp_transport *sctp_transport_get_idx(struct net *net,
+			struct rhashtable_iter *iter, int pos);
+int sctp_transport_lookup_process(sctp_callback_t cb, struct net *net,
+				  const union sctp_addr *laddr,
+				  const union sctp_addr *paddr, void *p);
+int sctp_transport_traverse_process(sctp_callback_t cb, sctp_callback_t cb_done,
+				    struct net *net, int *pos, void *p);
+int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), void *p);
+int sctp_get_sctp_info(struct sock *sk, struct sctp_association *asoc,
+		       struct sctp_info *info);
+
+/*
+ * sctp/primitive.c
+ */
+int sctp_primitive_ASSOCIATE(struct net *, struct sctp_association *, void *arg);
+int sctp_primitive_SHUTDOWN(struct net *, struct sctp_association *, void *arg);
+int sctp_primitive_ABORT(struct net *, struct sctp_association *, void *arg);
+int sctp_primitive_SEND(struct net *, struct sctp_association *, void *arg);
+int sctp_primitive_REQUESTHEARTBEAT(struct net *, struct sctp_association *, void *arg);
+int sctp_primitive_ASCONF(struct net *, struct sctp_association *, void *arg);
+int sctp_primitive_RECONF(struct net *net, struct sctp_association *asoc,
+			  void *arg);
+
+/*
+ * sctp/input.c
+ */
+int sctp_rcv(struct sk_buff *skb);
+int sctp_v4_err(struct sk_buff *skb, u32 info);
+int sctp_hash_endpoint(struct sctp_endpoint *ep);
+void sctp_unhash_endpoint(struct sctp_endpoint *);
+struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *,
+			     struct sctphdr *, struct sctp_association **,
+			     struct sctp_transport **);
+void sctp_err_finish(struct sock *, struct sctp_transport *);
+int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb);
+int sctp_udp_v6_err(struct sock *sk, struct sk_buff *skb);
+void sctp_icmp_frag_needed(struct sock *, struct sctp_association *,
+			   struct sctp_transport *t, __u32 pmtu);
+void sctp_icmp_redirect(struct sock *, struct sctp_transport *,
+			struct sk_buff *);
+void sctp_icmp_proto_unreachable(struct sock *sk,
+				 struct sctp_association *asoc,
+				 struct sctp_transport *t);
+void sctp_backlog_migrate(struct sctp_association *assoc,
+			  struct sock *oldsk, struct sock *newsk);
+int sctp_transport_hashtable_init(void);
+void sctp_transport_hashtable_destroy(void);
+int sctp_hash_transport(struct sctp_transport *t);
+void sctp_unhash_transport(struct sctp_transport *t);
+struct sctp_transport *sctp_addrs_lookup_transport(
+				struct net *net,
+				const union sctp_addr *laddr,
+				const union sctp_addr *paddr);
+struct sctp_transport *sctp_epaddr_lookup_transport(
+				const struct sctp_endpoint *ep,
+				const union sctp_addr *paddr);
+
+/*
+ * sctp/proc.c
+ */
+int __net_init sctp_proc_init(struct net *net);
+
+/*
+ * sctp/offload.c
+ */
+int sctp_offload_init(void);
+
+/*
+ * sctp/stream_sched.c
+ */
+void sctp_sched_ops_init(void);
+
+/*
+ * sctp/stream.c
+ */
+int sctp_send_reset_streams(struct sctp_association *asoc,
+			    struct sctp_reset_streams *params);
+int sctp_send_reset_assoc(struct sctp_association *asoc);
+int sctp_send_add_streams(struct sctp_association *asoc,
+			  struct sctp_add_streams *params);
+
+/*
+ * Module global variables
+ */
+
+ /*
+  * sctp/protocol.c
+  */
+extern struct kmem_cache *sctp_chunk_cachep __read_mostly;
+extern struct kmem_cache *sctp_bucket_cachep __read_mostly;
+extern long sysctl_sctp_mem[3];
+extern int sysctl_sctp_rmem[3];
+extern int sysctl_sctp_wmem[3];
+
+/*
+ *  Section:  Macros, externs, and inlines
+ */
+
+/* SCTP SNMP MIB stats handlers */
+#define SCTP_INC_STATS(net, field)	SNMP_INC_STATS((net)->sctp.sctp_statistics, field)
+#define __SCTP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->sctp.sctp_statistics, field)
+#define SCTP_DEC_STATS(net, field)	SNMP_DEC_STATS((net)->sctp.sctp_statistics, field)
+
+/* sctp mib definitions */
+enum {
+	SCTP_MIB_NUM = 0,
+	SCTP_MIB_CURRESTAB,			/* CurrEstab */
+	SCTP_MIB_ACTIVEESTABS,			/* ActiveEstabs */
+	SCTP_MIB_PASSIVEESTABS,			/* PassiveEstabs */
+	SCTP_MIB_ABORTEDS,			/* Aborteds */
+	SCTP_MIB_SHUTDOWNS,			/* Shutdowns */
+	SCTP_MIB_OUTOFBLUES,			/* OutOfBlues */
+	SCTP_MIB_CHECKSUMERRORS,		/* ChecksumErrors */
+	SCTP_MIB_OUTCTRLCHUNKS,			/* OutCtrlChunks */
+	SCTP_MIB_OUTORDERCHUNKS,		/* OutOrderChunks */
+	SCTP_MIB_OUTUNORDERCHUNKS,		/* OutUnorderChunks */
+	SCTP_MIB_INCTRLCHUNKS,			/* InCtrlChunks */
+	SCTP_MIB_INORDERCHUNKS,			/* InOrderChunks */
+	SCTP_MIB_INUNORDERCHUNKS,		/* InUnorderChunks */
+	SCTP_MIB_FRAGUSRMSGS,			/* FragUsrMsgs */
+	SCTP_MIB_REASMUSRMSGS,			/* ReasmUsrMsgs */
+	SCTP_MIB_OUTSCTPPACKS,			/* OutSCTPPacks */
+	SCTP_MIB_INSCTPPACKS,			/* InSCTPPacks */
+	SCTP_MIB_T1_INIT_EXPIREDS,
+	SCTP_MIB_T1_COOKIE_EXPIREDS,
+	SCTP_MIB_T2_SHUTDOWN_EXPIREDS,
+	SCTP_MIB_T3_RTX_EXPIREDS,
+	SCTP_MIB_T4_RTO_EXPIREDS,
+	SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS,
+	SCTP_MIB_DELAY_SACK_EXPIREDS,
+	SCTP_MIB_AUTOCLOSE_EXPIREDS,
+	SCTP_MIB_T1_RETRANSMITS,
+	SCTP_MIB_T3_RETRANSMITS,
+	SCTP_MIB_PMTUD_RETRANSMITS,
+	SCTP_MIB_FAST_RETRANSMITS,
+	SCTP_MIB_IN_PKT_SOFTIRQ,
+	SCTP_MIB_IN_PKT_BACKLOG,
+	SCTP_MIB_IN_PKT_DISCARDS,
+	SCTP_MIB_IN_DATA_CHUNK_DISCARDS,
+	__SCTP_MIB_MAX
+};
+
+#define SCTP_MIB_MAX    __SCTP_MIB_MAX
+struct sctp_mib {
+        unsigned long   mibs[SCTP_MIB_MAX];
+};
+
+/* helper function to track stats about max rto and related transport */
+static inline void sctp_max_rto(struct sctp_association *asoc,
+				struct sctp_transport *trans)
+{
+	if (asoc->stats.max_obs_rto < (__u64)trans->rto) {
+		asoc->stats.max_obs_rto = trans->rto;
+		memset(&asoc->stats.obs_rto_ipaddr, 0,
+			sizeof(struct sockaddr_storage));
+		memcpy(&asoc->stats.obs_rto_ipaddr, &trans->ipaddr,
+			trans->af_specific->sockaddr_len);
+	}
+}
+
+/*
+ * Macros for keeping a global reference of object allocations.
+ */
+#ifdef CONFIG_SCTP_DBG_OBJCNT
+
+extern atomic_t sctp_dbg_objcnt_sock;
+extern atomic_t sctp_dbg_objcnt_ep;
+extern atomic_t sctp_dbg_objcnt_assoc;
+extern atomic_t sctp_dbg_objcnt_transport;
+extern atomic_t sctp_dbg_objcnt_chunk;
+extern atomic_t sctp_dbg_objcnt_bind_addr;
+extern atomic_t sctp_dbg_objcnt_bind_bucket;
+extern atomic_t sctp_dbg_objcnt_addr;
+extern atomic_t sctp_dbg_objcnt_datamsg;
+extern atomic_t sctp_dbg_objcnt_keys;
+
+/* Macros to atomically increment/decrement objcnt counters.  */
+#define SCTP_DBG_OBJCNT_INC(name) \
+atomic_inc(&sctp_dbg_objcnt_## name)
+#define SCTP_DBG_OBJCNT_DEC(name) \
+atomic_dec(&sctp_dbg_objcnt_## name)
+#define SCTP_DBG_OBJCNT(name) \
+atomic_t sctp_dbg_objcnt_## name = ATOMIC_INIT(0)
+
+/* Macro to help create new entries in the global array of
+ * objcnt counters.
+ */
+#define SCTP_DBG_OBJCNT_ENTRY(name) \
+{.label= #name, .counter= &sctp_dbg_objcnt_## name}
+
+void sctp_dbg_objcnt_init(struct net *);
+
+#else
+
+#define SCTP_DBG_OBJCNT_INC(name)
+#define SCTP_DBG_OBJCNT_DEC(name)
+
+static inline void sctp_dbg_objcnt_init(struct net *net) { return; }
+
+#endif /* CONFIG_SCTP_DBG_OBJCOUNT */
+
+#if defined CONFIG_SYSCTL
+void sctp_sysctl_register(void);
+void sctp_sysctl_unregister(void);
+int sctp_sysctl_net_register(struct net *net);
+void sctp_sysctl_net_unregister(struct net *net);
+#else
+static inline void sctp_sysctl_register(void) { return; }
+static inline void sctp_sysctl_unregister(void) { return; }
+static inline int sctp_sysctl_net_register(struct net *net) { return 0; }
+static inline void sctp_sysctl_net_unregister(struct net *net) { return; }
+#endif
+
+/* Size of Supported Address Parameter for 'x' address types. */
+#define SCTP_SAT_LEN(x) (sizeof(struct sctp_paramhdr) + (x) * sizeof(__u16))
+
+#if IS_ENABLED(CONFIG_IPV6)
+
+void sctp_v6_pf_init(void);
+void sctp_v6_pf_exit(void);
+int sctp_v6_protosw_init(void);
+void sctp_v6_protosw_exit(void);
+int sctp_v6_add_protocol(void);
+void sctp_v6_del_protocol(void);
+
+#else /* #ifdef defined(CONFIG_IPV6) */
+
+static inline void sctp_v6_pf_init(void) { return; }
+static inline void sctp_v6_pf_exit(void) { return; }
+static inline int sctp_v6_protosw_init(void) { return 0; }
+static inline void sctp_v6_protosw_exit(void) { return; }
+static inline int sctp_v6_add_protocol(void) { return 0; }
+static inline void sctp_v6_del_protocol(void) { return; }
+
+#endif /* #if defined(CONFIG_IPV6) */
+
+
+/* Map an association to an assoc_id. */
+static inline sctp_assoc_t sctp_assoc2id(const struct sctp_association *asoc)
+{
+	return asoc ? asoc->assoc_id : 0;
+}
+
+static inline enum sctp_sstat_state
+sctp_assoc_to_state(const struct sctp_association *asoc)
+{
+	/* SCTP's uapi always had SCTP_EMPTY(=0) as a dummy state, but we
+	 * got rid of it in kernel space. Therefore SCTP_CLOSED et al
+	 * start at =1 in user space, but actually as =0 in kernel space.
+	 * Now that we can not break user space and SCTP_EMPTY is exposed
+	 * there, we need to fix it up with an ugly offset not to break
+	 * applications. :(
+	 */
+	return asoc->state + 1;
+}
+
+/* Look up the association by its id.  */
+struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id);
+
+int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp);
+
+/* A macro to walk a list of skbs.  */
+#define sctp_skb_for_each(pos, head, tmp) \
+	skb_queue_walk_safe(head, pos, tmp)
+
+/**
+ *	sctp_list_dequeue - remove from the head of the queue
+ *	@list: list to dequeue from
+ *
+ *	Remove the head of the list. The head item is
+ *	returned or %NULL if the list is empty.
+ */
+
+static inline struct list_head *sctp_list_dequeue(struct list_head *list)
+{
+	struct list_head *result = NULL;
+
+	if (!list_empty(list)) {
+		result = list->next;
+		list_del_init(result);
+	}
+	return result;
+}
+
+/* SCTP version of skb_set_owner_r.  We need this one because
+ * of the way we have to do receive buffer accounting on bundled
+ * chunks.
+ */
+static inline void sctp_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
+{
+	struct sctp_ulpevent *event = sctp_skb2event(skb);
+
+	skb_orphan(skb);
+	skb->sk = sk;
+	skb->destructor = sctp_sock_rfree;
+	atomic_add(event->rmem_len, &sk->sk_rmem_alloc);
+	/*
+	 * This mimics the behavior of skb_set_owner_r
+	 */
+	sk_mem_charge(sk, event->rmem_len);
+}
+
+/* Tests if the list has one and only one entry. */
+static inline int sctp_list_single_entry(struct list_head *head)
+{
+	return list_is_singular(head);
+}
+
+static inline bool sctp_chunk_pending(const struct sctp_chunk *chunk)
+{
+	return !list_empty(&chunk->list);
+}
+
+/* Walk through a list of TLV parameters.  Don't trust the
+ * individual parameter lengths and instead depend on
+ * the chunk length to indicate when to stop.  Make sure
+ * there is room for a param header too.
+ */
+#define sctp_walk_params(pos, chunk, member)\
+_sctp_walk_params((pos), (chunk), ntohs((chunk)->chunk_hdr.length), member)
+
+#define _sctp_walk_params(pos, chunk, end, member)\
+for (pos.v = chunk->member;\
+     (pos.v + offsetof(struct sctp_paramhdr, length) + sizeof(pos.p->length) <=\
+      (void *)chunk + end) &&\
+     pos.v <= (void *)chunk + end - ntohs(pos.p->length) &&\
+     ntohs(pos.p->length) >= sizeof(struct sctp_paramhdr);\
+     pos.v += SCTP_PAD4(ntohs(pos.p->length)))
+
+#define sctp_walk_errors(err, chunk_hdr)\
+_sctp_walk_errors((err), (chunk_hdr), ntohs((chunk_hdr)->length))
+
+#define _sctp_walk_errors(err, chunk_hdr, end)\
+for (err = (struct sctp_errhdr *)((void *)chunk_hdr + \
+	    sizeof(struct sctp_chunkhdr));\
+     ((void *)err + offsetof(struct sctp_errhdr, length) + sizeof(err->length) <=\
+      (void *)chunk_hdr + end) &&\
+     (void *)err <= (void *)chunk_hdr + end - ntohs(err->length) &&\
+     ntohs(err->length) >= sizeof(struct sctp_errhdr); \
+     err = (struct sctp_errhdr *)((void *)err + SCTP_PAD4(ntohs(err->length))))
+
+#define sctp_walk_fwdtsn(pos, chunk)\
+_sctp_walk_fwdtsn((pos), (chunk), ntohs((chunk)->chunk_hdr->length) - sizeof(struct sctp_fwdtsn_chunk))
+
+#define _sctp_walk_fwdtsn(pos, chunk, end)\
+for (pos = chunk->subh.fwdtsn_hdr->skip;\
+     (void *)pos <= (void *)chunk->subh.fwdtsn_hdr->skip + end - sizeof(struct sctp_fwdtsn_skip);\
+     pos++)
+
+/* External references. */
+
+extern struct proto sctp_prot;
+extern struct proto sctpv6_prot;
+void sctp_put_port(struct sock *sk);
+
+extern struct idr sctp_assocs_id;
+extern spinlock_t sctp_assocs_id_lock;
+
+/* Static inline functions. */
+
+/* Convert from an IP version number to an Address Family symbol.  */
+static inline int ipver2af(__u8 ipver)
+{
+	switch (ipver) {
+	case 4:
+	        return  AF_INET;
+	case 6:
+		return AF_INET6;
+	default:
+		return 0;
+	}
+}
+
+/* Convert from an address parameter type to an address family.  */
+static inline int param_type2af(__be16 type)
+{
+	switch (type) {
+	case SCTP_PARAM_IPV4_ADDRESS:
+	        return  AF_INET;
+	case SCTP_PARAM_IPV6_ADDRESS:
+		return AF_INET6;
+	default:
+		return 0;
+	}
+}
+
+/* Warning: The following hash functions assume a power of two 'size'. */
+/* This is the hash function for the SCTP port hash table. */
+static inline int sctp_phashfn(struct net *net, __u16 lport)
+{
+	return (net_hash_mix(net) + lport) & (sctp_port_hashsize - 1);
+}
+
+/* This is the hash function for the endpoint hash table. */
+static inline int sctp_ep_hashfn(struct net *net, __u16 lport)
+{
+	return (net_hash_mix(net) + lport) & (sctp_ep_hashsize - 1);
+}
+
+#define sctp_for_each_hentry(ep, head) \
+	hlist_for_each_entry(ep, head, node)
+
+/* Is a socket of this style? */
+#define sctp_style(sk, style) __sctp_style((sk), (SCTP_SOCKET_##style))
+static inline int __sctp_style(const struct sock *sk,
+			       enum sctp_socket_type style)
+{
+	return sctp_sk(sk)->type == style;
+}
+
+/* Is the association in this state? */
+#define sctp_state(asoc, state) __sctp_state((asoc), (SCTP_STATE_##state))
+static inline int __sctp_state(const struct sctp_association *asoc,
+			       enum sctp_state state)
+{
+	return asoc->state == state;
+}
+
+/* Is the socket in this state? */
+#define sctp_sstate(sk, state) __sctp_sstate((sk), (SCTP_SS_##state))
+static inline int __sctp_sstate(const struct sock *sk,
+				enum sctp_sock_state state)
+{
+	return sk->sk_state == state;
+}
+
+/* Map v4-mapped v6 address back to v4 address */
+static inline void sctp_v6_map_v4(union sctp_addr *addr)
+{
+	addr->v4.sin_family = AF_INET;
+	addr->v4.sin_port = addr->v6.sin6_port;
+	addr->v4.sin_addr.s_addr = addr->v6.sin6_addr.s6_addr32[3];
+}
+
+/* Map v4 address to v4-mapped v6 address */
+static inline void sctp_v4_map_v6(union sctp_addr *addr)
+{
+	__be16 port;
+
+	port = addr->v4.sin_port;
+	addr->v6.sin6_addr.s6_addr32[3] = addr->v4.sin_addr.s_addr;
+	addr->v6.sin6_port = port;
+	addr->v6.sin6_family = AF_INET6;
+	addr->v6.sin6_flowinfo = 0;
+	addr->v6.sin6_scope_id = 0;
+	addr->v6.sin6_addr.s6_addr32[0] = 0;
+	addr->v6.sin6_addr.s6_addr32[1] = 0;
+	addr->v6.sin6_addr.s6_addr32[2] = htonl(0x0000ffff);
+}
+
+/* The cookie is always 0 since this is how it's used in the
+ * pmtu code.
+ */
+static inline struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t)
+{
+	if (t->dst && !dst_check(t->dst, t->dst_cookie))
+		sctp_transport_dst_release(t);
+
+	return t->dst;
+}
+
+/* Calculate max payload size given a MTU, or the total overhead if
+ * given MTU is zero
+ */
+static inline __u32 __sctp_mtu_payload(const struct sctp_sock *sp,
+				       const struct sctp_transport *t,
+				       __u32 mtu, __u32 extra)
+{
+	__u32 overhead = sizeof(struct sctphdr) + extra;
+
+	if (sp) {
+		overhead += sp->pf->af->net_header_len;
+		if (sp->udp_port && (!t || t->encap_port))
+			overhead += sizeof(struct udphdr);
+	} else {
+		overhead += sizeof(struct ipv6hdr);
+	}
+
+	if (WARN_ON_ONCE(mtu && mtu <= overhead))
+		mtu = overhead;
+
+	return mtu ? mtu - overhead : overhead;
+}
+
+static inline __u32 sctp_mtu_payload(const struct sctp_sock *sp,
+				     __u32 mtu, __u32 extra)
+{
+	return __sctp_mtu_payload(sp, NULL, mtu, extra);
+}
+
+static inline __u32 sctp_dst_mtu(const struct dst_entry *dst)
+{
+	return SCTP_TRUNC4(max_t(__u32, dst_mtu(dst),
+				 SCTP_DEFAULT_MINSEGMENT));
+}
+
+static inline bool sctp_transport_pmtu_check(struct sctp_transport *t)
+{
+	__u32 pmtu = sctp_dst_mtu(t->dst);
+
+	if (t->pathmtu == pmtu)
+		return true;
+
+	t->pathmtu = pmtu;
+
+	return false;
+}
+
+static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize)
+{
+	return sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, datasize);
+}
+
+static inline int sctp_transport_pl_hlen(struct sctp_transport *t)
+{
+	return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0) -
+	       sizeof(struct sctphdr);
+}
+
+static inline void sctp_transport_pl_reset(struct sctp_transport *t)
+{
+	if (t->probe_interval && (t->param_flags & SPP_PMTUD_ENABLE) &&
+	    (t->state == SCTP_ACTIVE || t->state == SCTP_UNKNOWN)) {
+		if (t->pl.state == SCTP_PL_DISABLED) {
+			t->pl.state = SCTP_PL_BASE;
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pl.probe_size = SCTP_BASE_PLPMTU;
+			sctp_transport_reset_probe_timer(t);
+		}
+	} else {
+		if (t->pl.state != SCTP_PL_DISABLED) {
+			if (del_timer(&t->probe_timer))
+				sctp_transport_put(t);
+			t->pl.state = SCTP_PL_DISABLED;
+		}
+	}
+}
+
+static inline void sctp_transport_pl_update(struct sctp_transport *t)
+{
+	if (t->pl.state == SCTP_PL_DISABLED)
+		return;
+
+	t->pl.state = SCTP_PL_BASE;
+	t->pl.pmtu = SCTP_BASE_PLPMTU;
+	t->pl.probe_size = SCTP_BASE_PLPMTU;
+	sctp_transport_reset_probe_timer(t);
+}
+
+static inline bool sctp_transport_pl_enabled(struct sctp_transport *t)
+{
+	return t->pl.state != SCTP_PL_DISABLED;
+}
+
+static inline bool sctp_newsk_ready(const struct sock *sk)
+{
+	return sock_flag(sk, SOCK_DEAD) || sk->sk_socket;
+}
+
+static inline void sctp_sock_set_nodelay(struct sock *sk)
+{
+	lock_sock(sk);
+	sctp_sk(sk)->nodelay = true;
+	release_sock(sk);
+}
+
+#endif /* __net_sctp_h__ */