Merge branch 'sctp-clean-up-sctp_sendmsg'

Xin Long says:

====================
sctp: clean up sctp_sendmsg

This cleanup mostly does three things:

 - extract some codes into functions to make sendmsg more readable.

 - tidy up some codes to avoid the unnecessary checks.

 - adjust some logic so that it will be easier to add the send flags
   and cmsgs features that I will post after this.

To make it easy to review and to check if the code is compatible with
before, this patchset is to do it step by step in 9 patches.

NOTE:
There will be a conflict when merging
Commit 2277c7cd ("sctp: Add LSM hooks") from selinux tree,
the solution is to:

1. remove all the lines in [B]:

    <<<<<<< HEAD
    [A]
    =======
    [B]
    >>>>>>> 2277c7cd... sctp: Add LSM hooks

2. and apply the following diff-output:

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 980621e..d6803c8 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1686,6 +1686,7 @@ static int sctp_sendmsg_new_asoc(struct sock *sk, __u16 sflags,
 	struct net *net = sock_net(sk);
 	struct sctp_association *asoc;
 	enum sctp_scope scope;
+	struct sctp_af *af;
 	int err = -EINVAL;

 	*tp = NULL;
@@ -1711,6 +1712,22 @@ static int sctp_sendmsg_new_asoc(struct sock *sk, __u16 sflags,

 	scope = sctp_scope(daddr);

+	/* Label connection socket for first association 1-to-many
+	 * style for client sequence socket()->sendmsg(). This
+	 * needs to be done before sctp_assoc_add_peer() as that will
+	 * set up the initial packet that needs to account for any
+	 * security ip options (CIPSO/CALIPSO) added to the packet.
+	 */
+	af = sctp_get_af_specific(daddr->sa.sa_family);
+	if (!af)
+		return -EINVAL;
+
+	err = security_sctp_bind_connect(sk, SCTP_SENDMSG_CONNECT,
+					 (struct sockaddr *)daddr,
+					 af->sockaddr_len);
+	if (err < 0)
+		return err;
+
 	asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
 	if (!asoc)
 		return -ENOMEM;
====================
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -1606,396 +1606,214 @@ static int sctp_error(struct sock *sk, int flags, int err)
 static int sctp_msghdr_parse(const struct msghdr *msg,
 			     struct sctp_cmsgs *cmsgs);
 
-static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
+static int sctp_sendmsg_parse(struct sock *sk, struct sctp_cmsgs *cmsgs,
+			      struct sctp_sndrcvinfo *srinfo,
+			      const struct msghdr *msg, size_t msg_len)
 {
-	struct net *net = sock_net(sk);
-	struct sctp_sock *sp;
-	struct sctp_endpoint *ep;
-	struct sctp_association *new_asoc = NULL, *asoc = NULL;
-	struct sctp_transport *transport, *chunk_tp;
-	struct sctp_chunk *chunk;
-	union sctp_addr to;
-	struct sockaddr *msg_name = NULL;
-	struct sctp_sndrcvinfo default_sinfo;
-	struct sctp_sndrcvinfo *sinfo;
-	struct sctp_initmsg *sinit;
-	sctp_assoc_t associd = 0;
-	struct sctp_cmsgs cmsgs = { NULL };
-	enum sctp_scope scope;
-	bool fill_sinfo_ttl = false, wait_connect = false;
-	struct sctp_datamsg *datamsg;
-	int msg_flags = msg->msg_flags;
-	__u16 sinfo_flags = 0;
-	long timeo;
+	__u16 sflags;
 	int err;
 
-	err = 0;
-	sp = sctp_sk(sk);
-	ep = sp->ep;
+	if (sctp_sstate(sk, LISTENING) && sctp_style(sk, TCP))
+		return -EPIPE;
 
-	pr_debug("%s: sk:%p, msg:%p, msg_len:%zu ep:%p\n", __func__, sk,
-		 msg, msg_len, ep);
+	if (msg_len > sk->sk_sndbuf)
+		return -EMSGSIZE;
 
-	/* We cannot send a message over a TCP-style listening socket. */
-	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING)) {
-		err = -EPIPE;
-		goto out_nounlock;
-	}
-
-	/* Parse out the SCTP CMSGs.  */
-	err = sctp_msghdr_parse(msg, &cmsgs);
+	memset(cmsgs, 0, sizeof(*cmsgs));
+	err = sctp_msghdr_parse(msg, cmsgs);
 	if (err) {
 		pr_debug("%s: msghdr parse err:%x\n", __func__, err);
-		goto out_nounlock;
-	}
-
-	/* Fetch the destination address for this packet.  This
-	 * address only selects the association--it is not necessarily
-	 * the address we will send to.
-	 * For a peeled-off socket, msg_name is ignored.
-	 */
-	if (!sctp_style(sk, UDP_HIGH_BANDWIDTH) && msg->msg_name) {
-		int msg_namelen = msg->msg_namelen;
-
-		err = sctp_verify_addr(sk, (union sctp_addr *)msg->msg_name,
-				       msg_namelen);
-		if (err)
 		return err;
-
-		if (msg_namelen > sizeof(to))
-			msg_namelen = sizeof(to);
-		memcpy(&to, msg->msg_name, msg_namelen);
-		msg_name = msg->msg_name;
 	}
 
-	sinit = cmsgs.init;
-	if (cmsgs.sinfo != NULL) {
-		memset(&default_sinfo, 0, sizeof(default_sinfo));
-		default_sinfo.sinfo_stream = cmsgs.sinfo->snd_sid;
-		default_sinfo.sinfo_flags = cmsgs.sinfo->snd_flags;
-		default_sinfo.sinfo_ppid = cmsgs.sinfo->snd_ppid;
-		default_sinfo.sinfo_context = cmsgs.sinfo->snd_context;
-		default_sinfo.sinfo_assoc_id = cmsgs.sinfo->snd_assoc_id;
-
-		sinfo = &default_sinfo;
-		fill_sinfo_ttl = true;
-	} else {
-		sinfo = cmsgs.srinfo;
-	}
-	/* Did the user specify SNDINFO/SNDRCVINFO? */
-	if (sinfo) {
-		sinfo_flags = sinfo->sinfo_flags;
-		associd = sinfo->sinfo_assoc_id;
+	memset(srinfo, 0, sizeof(*srinfo));
+	if (cmsgs->srinfo) {
+		srinfo->sinfo_stream = cmsgs->srinfo->sinfo_stream;
+		srinfo->sinfo_flags = cmsgs->srinfo->sinfo_flags;
+		srinfo->sinfo_ppid = cmsgs->srinfo->sinfo_ppid;
+		srinfo->sinfo_context = cmsgs->srinfo->sinfo_context;
+		srinfo->sinfo_assoc_id = cmsgs->srinfo->sinfo_assoc_id;
+		srinfo->sinfo_timetolive = cmsgs->srinfo->sinfo_timetolive;
 	}
 
-	pr_debug("%s: msg_len:%zu, sinfo_flags:0x%x\n", __func__,
-		 msg_len, sinfo_flags);
-
-	/* SCTP_EOF or SCTP_ABORT cannot be set on a TCP-style socket. */
-	if (sctp_style(sk, TCP) && (sinfo_flags & (SCTP_EOF | SCTP_ABORT))) {
-		err = -EINVAL;
-		goto out_nounlock;
+	if (cmsgs->sinfo) {
+		srinfo->sinfo_stream = cmsgs->sinfo->snd_sid;
+		srinfo->sinfo_flags = cmsgs->sinfo->snd_flags;
+		srinfo->sinfo_ppid = cmsgs->sinfo->snd_ppid;
+		srinfo->sinfo_context = cmsgs->sinfo->snd_context;
+		srinfo->sinfo_assoc_id = cmsgs->sinfo->snd_assoc_id;
 	}
 
-	/* If SCTP_EOF is set, no data can be sent. Disallow sending zero
-	 * length messages when SCTP_EOF|SCTP_ABORT is not set.
-	 * If SCTP_ABORT is set, the message length could be non zero with
-	 * the msg_iov set to the user abort reason.
-	 */
-	if (((sinfo_flags & SCTP_EOF) && (msg_len > 0)) ||
-	    (!(sinfo_flags & (SCTP_EOF|SCTP_ABORT)) && (msg_len == 0))) {
-		err = -EINVAL;
-		goto out_nounlock;
-	}
-
-	/* If SCTP_ADDR_OVER is set, there must be an address
-	 * specified in msg_name.
-	 */
-	if ((sinfo_flags & SCTP_ADDR_OVER) && (!msg->msg_name)) {
-		err = -EINVAL;
-		goto out_nounlock;
-	}
-
-	transport = NULL;
-
-	pr_debug("%s: about to look up association\n", __func__);
-
-	lock_sock(sk);
-
-	/* If a msg_name has been specified, assume this is to be used.  */
-	if (msg_name) {
-		/* Look for a matching association on the endpoint. */
-		asoc = sctp_endpoint_lookup_assoc(ep, &to, &transport);
-
-		/* If we could not find a matching association on the
-		 * endpoint, make sure that it is not a TCP-style
-		 * socket that already has an association or there is
-		 * no peeled-off association on another socket.
-		 */
-		if (!asoc &&
-		    ((sctp_style(sk, TCP) &&
-		      (sctp_sstate(sk, ESTABLISHED) ||
-		       sctp_sstate(sk, CLOSING))) ||
-		     sctp_endpoint_is_peeled_off(ep, &to))) {
-			err = -EADDRNOTAVAIL;
-			goto out_unlock;
-		}
-	} else {
-		asoc = sctp_id2assoc(sk, associd);
-		if (!asoc) {
-			err = -EPIPE;
-			goto out_unlock;
-		}
-	}
-
-	if (asoc) {
-		pr_debug("%s: just looked up association:%p\n", __func__, asoc);
+	sflags = srinfo->sinfo_flags;
+	if (!sflags && msg_len)
+		return 0;
 
-		/* We cannot send a message on a TCP-style SCTP_SS_ESTABLISHED
-		 * socket that has an association in CLOSED state. This can
-		 * happen when an accepted socket has an association that is
-		 * already CLOSED.
-		 */
-		if (sctp_state(asoc, CLOSED) && sctp_style(sk, TCP)) {
-			err = -EPIPE;
-			goto out_unlock;
-		}
+	if (sctp_style(sk, TCP) && (sflags & (SCTP_EOF | SCTP_ABORT)))
+		return -EINVAL;
 
-		if (sinfo_flags & SCTP_EOF) {
-			pr_debug("%s: shutting down association:%p\n",
-				 __func__, asoc);
+	if (((sflags & SCTP_EOF) && msg_len > 0) ||
+	    (!(sflags & (SCTP_EOF | SCTP_ABORT)) && msg_len == 0))
+		return -EINVAL;
 
-			sctp_primitive_SHUTDOWN(net, asoc, NULL);
-			err = 0;
-			goto out_unlock;
-		}
-		if (sinfo_flags & SCTP_ABORT) {
+	if ((sflags & SCTP_ADDR_OVER) && !msg->msg_name)
+		return -EINVAL;
 
-			chunk = sctp_make_abort_user(asoc, msg, msg_len);
-			if (!chunk) {
-				err = -ENOMEM;
-				goto out_unlock;
-			}
+	return 0;
+}
 
-			pr_debug("%s: aborting association:%p\n",
-				 __func__, asoc);
+static int sctp_sendmsg_new_asoc(struct sock *sk, __u16 sflags,
+				 struct sctp_cmsgs *cmsgs,
+				 union sctp_addr *daddr,
+				 struct sctp_transport **tp)
+{
+	struct sctp_endpoint *ep = sctp_sk(sk)->ep;
+	struct net *net = sock_net(sk);
+	struct sctp_association *asoc;
+	enum sctp_scope scope;
+	int err = -EINVAL;
 
-			sctp_primitive_ABORT(net, asoc, chunk);
-			err = 0;
-			goto out_unlock;
-		}
-	}
+	*tp = NULL;
 
-	/* Do we need to create the association?  */
-	if (!asoc) {
-		pr_debug("%s: there is no association yet\n", __func__);
+	if (sflags & (SCTP_EOF | SCTP_ABORT))
+		return -EINVAL;
 
-		if (sinfo_flags & (SCTP_EOF | SCTP_ABORT)) {
-			err = -EINVAL;
-			goto out_unlock;
-		}
+	if (sctp_style(sk, TCP) && (sctp_sstate(sk, ESTABLISHED) ||
+				    sctp_sstate(sk, CLOSING)))
+		return -EADDRNOTAVAIL;
 
-		/* Check for invalid stream against the stream counts,
-		 * either the default or the user specified stream counts.
-		 */
-		if (sinfo) {
-			if (!sinit || !sinit->sinit_num_ostreams) {
-				/* Check against the defaults. */
-				if (sinfo->sinfo_stream >=
-				    sp->initmsg.sinit_num_ostreams) {
-					err = -EINVAL;
-					goto out_unlock;
-				}
-			} else {
-				/* Check against the requested.  */
-				if (sinfo->sinfo_stream >=
-				    sinit->sinit_num_ostreams) {
-					err = -EINVAL;
-					goto out_unlock;
-				}
-			}
-		}
+	if (sctp_endpoint_is_peeled_off(ep, daddr))
+		return -EADDRNOTAVAIL;
 
-		/*
-		 * API 3.1.2 bind() - UDP Style Syntax
-		 * If a bind() or sctp_bindx() is not called prior to a
-		 * sendmsg() call that initiates a new association, the
-		 * system picks an ephemeral port and will choose an address
-		 * set equivalent to binding with a wildcard address.
-		 */
 	if (!ep->base.bind_addr.port) {
-			if (sctp_autobind(sk)) {
-				err = -EAGAIN;
-				goto out_unlock;
-			}
+		if (sctp_autobind(sk))
+			return -EAGAIN;
 	} else {
-			/*
-			 * If an unprivileged user inherits a one-to-many
-			 * style socket with open associations on a privileged
-			 * port, it MAY be permitted to accept new associations,
-			 * but it SHOULD NOT be permitted to open new
-			 * associations.
-			 */
 		if (ep->base.bind_addr.port < inet_prot_sock(net) &&
-			    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) {
-				err = -EACCES;
-				goto out_unlock;
-			}
+		    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE))
+			return -EACCES;
 	}
 
-		scope = sctp_scope(&to);
-		new_asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
-		if (!new_asoc) {
-			err = -ENOMEM;
-			goto out_unlock;
-		}
-		asoc = new_asoc;
-		err = sctp_assoc_set_bind_addr_from_ep(asoc, scope, GFP_KERNEL);
-		if (err < 0) {
+	scope = sctp_scope(daddr);
+
+	asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
+	if (!asoc)
+		return -ENOMEM;
+
+	if (sctp_assoc_set_bind_addr_from_ep(asoc, scope, GFP_KERNEL) < 0) {
 		err = -ENOMEM;
-			goto out_free;
+		goto free;
 	}
 
-		/* If the SCTP_INIT ancillary data is specified, set all
-		 * the association init values accordingly.
-		 */
-		if (sinit) {
-			if (sinit->sinit_num_ostreams) {
-				__u16 outcnt = sinit->sinit_num_ostreams;
+	if (cmsgs->init) {
+		struct sctp_initmsg *init = cmsgs->init;
+
+		if (init->sinit_num_ostreams) {
+			__u16 outcnt = init->sinit_num_ostreams;
 
 			asoc->c.sinit_num_ostreams = outcnt;
-				/* outcnt has been changed, so re-init stream */
+			/* outcnt has been changed, need to re-init stream */
 			err = sctp_stream_init(&asoc->stream, outcnt, 0,
 					       GFP_KERNEL);
 			if (err)
-					goto out_free;
-			}
-			if (sinit->sinit_max_instreams) {
-				asoc->c.sinit_max_instreams =
-					sinit->sinit_max_instreams;
+				goto free;
 		}
-			if (sinit->sinit_max_attempts) {
-				asoc->max_init_attempts
-					= sinit->sinit_max_attempts;
-			}
-			if (sinit->sinit_max_init_timeo) {
+
+		if (init->sinit_max_instreams)
+			asoc->c.sinit_max_instreams = init->sinit_max_instreams;
+
+		if (init->sinit_max_attempts)
+			asoc->max_init_attempts = init->sinit_max_attempts;
+
+		if (init->sinit_max_init_timeo)
 			asoc->max_init_timeo =
-				 msecs_to_jiffies(sinit->sinit_max_init_timeo);
-			}
+				msecs_to_jiffies(init->sinit_max_init_timeo);
 	}
 
-		/* Prime the peer's transport structures.  */
-		transport = sctp_assoc_add_peer(asoc, &to, GFP_KERNEL, SCTP_UNKNOWN);
-		if (!transport) {
+	*tp = sctp_assoc_add_peer(asoc, daddr, GFP_KERNEL, SCTP_UNKNOWN);
+	if (!*tp) {
 		err = -ENOMEM;
-			goto out_free;
-		}
+		goto free;
 	}
 
-	/* ASSERT: we have a valid association at this point.  */
-	pr_debug("%s: we have a valid association\n", __func__);
+	return 0;
 
-	if (!sinfo) {
-		/* If the user didn't specify SNDINFO/SNDRCVINFO, make up
-		 * one with some defaults.
-		 */
-		memset(&default_sinfo, 0, sizeof(default_sinfo));
-		default_sinfo.sinfo_stream = asoc->default_stream;
-		default_sinfo.sinfo_flags = asoc->default_flags;
-		default_sinfo.sinfo_ppid = asoc->default_ppid;
-		default_sinfo.sinfo_context = asoc->default_context;
-		default_sinfo.sinfo_timetolive = asoc->default_timetolive;
-		default_sinfo.sinfo_assoc_id = sctp_assoc2id(asoc);
+free:
+	sctp_association_free(asoc);
+	return err;
+}
 
-		sinfo = &default_sinfo;
-	} else if (fill_sinfo_ttl) {
-		/* In case SNDINFO was specified, we still need to fill
-		 * it with a default ttl from the assoc here.
-		 */
-		sinfo->sinfo_timetolive = asoc->default_timetolive;
-	}
+static int sctp_sendmsg_check_sflags(struct sctp_association *asoc,
+				     __u16 sflags, struct msghdr *msg,
+				     size_t msg_len)
+{
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
 
-	/* API 7.1.7, the sndbuf size per association bounds the
-	 * maximum size of data that can be sent in a single send call.
-	 */
-	if (msg_len > sk->sk_sndbuf) {
-		err = -EMSGSIZE;
-		goto out_free;
+	if (sctp_state(asoc, CLOSED) && sctp_style(sk, TCP))
+		return -EPIPE;
+
+	if (sflags & SCTP_EOF) {
+		pr_debug("%s: shutting down association:%p\n", __func__, asoc);
+		sctp_primitive_SHUTDOWN(net, asoc, NULL);
+
+		return 0;
 	}
 
-	if (asoc->pmtu_pending)
-		sctp_assoc_pending_pmtu(asoc);
+	if (sflags & SCTP_ABORT) {
+		struct sctp_chunk *chunk;
 
-	/* If fragmentation is disabled and the message length exceeds the
-	 * association fragmentation point, return EMSGSIZE.  The I-D
-	 * does not specify what this error is, but this looks like
-	 * a great fit.
-	 */
-	if (sctp_sk(sk)->disable_fragments && (msg_len > asoc->frag_point)) {
-		err = -EMSGSIZE;
-		goto out_free;
+		chunk = sctp_make_abort_user(asoc, msg, msg_len);
+		if (!chunk)
+			return -ENOMEM;
+
+		pr_debug("%s: aborting association:%p\n", __func__, asoc);
+		sctp_primitive_ABORT(net, asoc, chunk);
+
+		return 0;
 	}
 
-	/* Check for invalid stream. */
+	return 1;
+}
+
+static int sctp_sendmsg_to_asoc(struct sctp_association *asoc,
+				struct msghdr *msg, size_t msg_len,
+				struct sctp_transport *transport,
+				struct sctp_sndrcvinfo *sinfo)
+{
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+	struct sctp_datamsg *datamsg;
+	bool wait_connect = false;
+	struct sctp_chunk *chunk;
+	long timeo;
+	int err;
+
 	if (sinfo->sinfo_stream >= asoc->stream.outcnt) {
 		err = -EINVAL;
-		goto out_free;
+		goto err;
 	}
 
-	/* Allocate sctp_stream_out_ext if not already done */
 	if (unlikely(!asoc->stream.out[sinfo->sinfo_stream].ext)) {
 		err = sctp_stream_init_ext(&asoc->stream, sinfo->sinfo_stream);
 		if (err)
-			goto out_free;
+			goto err;
 	}
 
-	if (sctp_wspace(asoc) < msg_len)
-		sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc));
-
-	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
-	if (!sctp_wspace(asoc)) {
-		/* sk can be changed by peel off when waiting for buf. */
-		err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
-		if (err) {
-			if (err == -ESRCH) {
-				/* asoc is already dead. */
-				new_asoc = NULL;
-				err = -EPIPE;
-			}
-			goto out_free;
-		}
-	}
-
-	/* If an address is passed with the sendto/sendmsg call, it is used
-	 * to override the primary destination address in the TCP model, or
-	 * when SCTP_ADDR_OVER flag is set in the UDP model.
-	 */
-	if ((sctp_style(sk, TCP) && msg_name) ||
-	    (sinfo_flags & SCTP_ADDR_OVER)) {
-		chunk_tp = sctp_assoc_lookup_paddr(asoc, &to);
-		if (!chunk_tp) {
-			err = -EINVAL;
-			goto out_free;
+	if (sctp_sk(sk)->disable_fragments && msg_len > asoc->frag_point) {
+		err = -EMSGSIZE;
+		goto err;
 	}
-	} else
-		chunk_tp = NULL;
 
-	/* Auto-connect, if we aren't connected already. */
 	if (sctp_state(asoc, CLOSED)) {
 		err = sctp_primitive_ASSOCIATE(net, asoc, NULL);
-		if (err < 0)
-			goto out_free;
+		if (err)
+			goto err;
 
-		/* If stream interleave is enabled, wait_connect has to be
-		 * done earlier than data enqueue, as it needs to make data
-		 * or idata according to asoc->intl_enable which is set
-		 * after connection is done.
-		 */
-		if (sctp_sk(asoc->base.sk)->strm_interleave) {
+		if (sctp_sk(sk)->strm_interleave) {
 			timeo = sock_sndtimeo(sk, 0);
 			err = sctp_wait_for_connect(asoc, &timeo);
 			if (err)
-				goto out_unlock;
+				goto err;
 		} else {
 			wait_connect = true;
 		}
@@ -2003,73 +1821,165 @@ static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
 		pr_debug("%s: we associated primitively\n", __func__);
 	}
 
-	/* Break the message into multiple chunks of maximum size. */
+	if (asoc->pmtu_pending)
+		sctp_assoc_pending_pmtu(asoc);
+
+	if (sctp_wspace(asoc) < msg_len)
+		sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc));
+
+	if (!sctp_wspace(asoc)) {
+		timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
+		err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
+		if (err)
+			goto err;
+	}
+
 	datamsg = sctp_datamsg_from_user(asoc, sinfo, &msg->msg_iter);
 	if (IS_ERR(datamsg)) {
 		err = PTR_ERR(datamsg);
-		goto out_free;
+		goto err;
 	}
+
 	asoc->force_delay = !!(msg->msg_flags & MSG_MORE);
 
-	/* Now send the (possibly) fragmented message. */
 	list_for_each_entry(chunk, &datamsg->chunks, frag_list) {
 		sctp_chunk_hold(chunk);
-
-		/* Do accounting for the write space.  */
 		sctp_set_owner_w(chunk);
-
-		chunk->transport = chunk_tp;
+		chunk->transport = transport;
 	}
 
-	/* Send it to the lower layers.  Note:  all chunks
-	 * must either fail or succeed.   The lower layer
-	 * works that way today.  Keep it that way or this
-	 * breaks.
-	 */
 	err = sctp_primitive_SEND(net, asoc, datamsg);
-	/* Did the lower layer accept the chunk? */
 	if (err) {
 		sctp_datamsg_free(datamsg);
-		goto out_free;
+		goto err;
 	}
 
 	pr_debug("%s: we sent primitively\n", __func__);
 
 	sctp_datamsg_put(datamsg);
-	err = msg_len;
 
 	if (unlikely(wait_connect)) {
-		timeo = sock_sndtimeo(sk, msg_flags & MSG_DONTWAIT);
+		timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 		sctp_wait_for_connect(asoc, &timeo);
 	}
 
-	/* If we are already past ASSOCIATE, the lower
-	 * layers are responsible for association cleanup.
-	 */
-	goto out_unlock;
+	err = msg_len;
 
-out_free:
-	if (new_asoc)
-		sctp_association_free(asoc);
-out_unlock:
-	release_sock(sk);
+err:
+	return err;
+}
 
-out_nounlock:
-	return sctp_error(sk, msg_flags, err);
+static union sctp_addr *sctp_sendmsg_get_daddr(struct sock *sk,
+					       const struct msghdr *msg,
+					       struct sctp_cmsgs *cmsgs)
+{
+	union sctp_addr *daddr = NULL;
+	int err;
 
-#if 0
-do_sock_err:
-	if (msg_len)
-		err = msg_len;
-	else
-		err = sock_error(sk);
+	if (!sctp_style(sk, UDP_HIGH_BANDWIDTH) && msg->msg_name) {
+		int len = msg->msg_namelen;
+
+		if (len > sizeof(*daddr))
+			len = sizeof(*daddr);
+
+		daddr = (union sctp_addr *)msg->msg_name;
+
+		err = sctp_verify_addr(sk, daddr, len);
+		if (err)
+			return ERR_PTR(err);
+	}
+
+	return daddr;
+}
+
+static void sctp_sendmsg_update_sinfo(struct sctp_association *asoc,
+				      struct sctp_sndrcvinfo *sinfo,
+				      struct sctp_cmsgs *cmsgs)
+{
+	if (!cmsgs->srinfo && !cmsgs->sinfo) {
+		sinfo->sinfo_stream = asoc->default_stream;
+		sinfo->sinfo_ppid = asoc->default_ppid;
+		sinfo->sinfo_context = asoc->default_context;
+		sinfo->sinfo_assoc_id = sctp_assoc2id(asoc);
+	}
+
+	if (!cmsgs->srinfo)
+		sinfo->sinfo_timetolive = asoc->default_timetolive;
+}
+
+static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
+{
+	struct sctp_endpoint *ep = sctp_sk(sk)->ep;
+	struct sctp_transport *transport = NULL;
+	struct sctp_sndrcvinfo _sinfo, *sinfo;
+	struct sctp_association *asoc;
+	struct sctp_cmsgs cmsgs;
+	union sctp_addr *daddr;
+	bool new = false;
+	__u16 sflags;
+	int err;
+
+	/* Parse and get snd_info */
+	err = sctp_sendmsg_parse(sk, &cmsgs, &_sinfo, msg, msg_len);
+	if (err)
 		goto out;
 
-do_interrupted:
-	if (msg_len)
-		err = msg_len;
+	sinfo  = &_sinfo;
+	sflags = sinfo->sinfo_flags;
+
+	/* Get daddr from msg */
+	daddr = sctp_sendmsg_get_daddr(sk, msg, &cmsgs);
+	if (IS_ERR(daddr)) {
+		err = PTR_ERR(daddr);
 		goto out;
-#endif /* 0 */
+	}
+
+	lock_sock(sk);
+
+	/* Get and check or create asoc */
+	if (daddr) {
+		asoc = sctp_endpoint_lookup_assoc(ep, daddr, &transport);
+		if (asoc) {
+			err = sctp_sendmsg_check_sflags(asoc, sflags, msg,
+							msg_len);
+			if (err <= 0)
+				goto out_unlock;
+		} else {
+			err = sctp_sendmsg_new_asoc(sk, sflags, &cmsgs, daddr,
+						    &transport);
+			if (err)
+				goto out_unlock;
+
+			asoc = transport->asoc;
+			new = true;
+		}
+
+		if (!sctp_style(sk, TCP) && !(sflags & SCTP_ADDR_OVER))
+			transport = NULL;
+	} else {
+		asoc = sctp_id2assoc(sk, sinfo->sinfo_assoc_id);
+		if (!asoc) {
+			err = -EPIPE;
+			goto out_unlock;
+		}
+
+		err = sctp_sendmsg_check_sflags(asoc, sflags, msg, msg_len);
+		if (err <= 0)
+			goto out_unlock;
+	}
+
+	/* Update snd_info with the asoc */
+	sctp_sendmsg_update_sinfo(asoc, sinfo, &cmsgs);
+
+	/* Send msg to the asoc */
+	err = sctp_sendmsg_to_asoc(asoc, msg, msg_len, transport, sinfo);
+	if (err < 0 && err != -ESRCH && new)
+		sctp_association_free(asoc);
+
+out_unlock:
+	release_sock(sk);
+out:
+	return sctp_error(sk, msg->msg_flags, err);
 }
 
 /* This is an extended version of skb_pull() that removes the data from the