Commit message: net: sctp: inherit auth_capable on INIT collisions

Jason reported an oops caused by SCTP on his ARM machine with
SCTP authentication enabled:

Internal error: Oops: 17 [#1] ARM
CPU: 0 PID: 104 Comm: sctp-test Not tainted 3.13.0-68744-g3632f30c9b20-dirty #1
task: c6eefa40 ti: c6f52000 task.ti: c6f52000
PC is at sctp_auth_calculate_hmac+0xc4/0x10c
LR is at sg_init_table+0x20/0x38
pc : [<c024bb80>]    lr : [<c00f32dc>]    psr: 40000013
sp : c6f538e8  ip : 00000000  fp : c6f53924
r10: c6f50d80  r9 : 00000000  r8 : 00010000
r7 : 00000000  r6 : c7be4000  r5 : 00000000  r4 : c6f56254
r3 : c00c8170  r2 : 00000001  r1 : 00000008  r0 : c6f1e660
Flags: nZcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 0005397f  Table: 06f28000  DAC: 00000015
Process sctp-test (pid: 104, stack limit = 0xc6f521c0)
Stack: (0xc6f538e8 to 0xc6f54000)
[...]
Backtrace:
[<c024babc>] (sctp_auth_calculate_hmac+0x0/0x10c) from [<c0249af8>] (sctp_packet_transmit+0x33c/0x5c8)
[<c02497bc>] (sctp_packet_transmit+0x0/0x5c8) from [<c023e96c>] (sctp_outq_flush+0x7fc/0x844)
[<c023e170>] (sctp_outq_flush+0x0/0x844) from [<c023ef78>] (sctp_outq_uncork+0x24/0x28)
[<c023ef54>] (sctp_outq_uncork+0x0/0x28) from [<c0234364>] (sctp_side_effects+0x1134/0x1220)
[<c0233230>] (sctp_side_effects+0x0/0x1220) from [<c02330b0>] (sctp_do_sm+0xac/0xd4)
[<c0233004>] (sctp_do_sm+0x0/0xd4) from [<c023675c>] (sctp_assoc_bh_rcv+0x118/0x160)
[<c0236644>] (sctp_assoc_bh_rcv+0x0/0x160) from [<c023d5bc>] (sctp_inq_push+0x6c/0x74)
[<c023d550>] (sctp_inq_push+0x0/0x74) from [<c024a6b0>] (sctp_rcv+0x7d8/0x888)

While we already had various kind of bugs in that area
ec0223ec48a9 ("net: sctp: fix sctp_sf_do_5_1D_ce to verify if
we/peer is AUTH capable") and b14878ccb7fa ("net: sctp: cache
auth_enable per endpoint"), this one is a bit of a different
kind.

Giving a bit more background on why SCTP authentication is
needed can be found in RFC4895:

  SCTP uses 32-bit verification tags to protect itself against
  blind attackers. These values are not changed during the
  lifetime of an SCTP association.

  Looking at new SCTP extensions, there is the need to have a
  method of proving that an SCTP chunk(s) was really sent by
  the original peer that started the association and not by a
  malicious attacker.

To cause this bug, we're triggering an INIT collision between
peers; normal SCTP handshake where both sides intent to
authenticate packets contains RANDOM; CHUNKS; HMAC-ALGO
parameters that are being negotiated among peers:

  ---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ---------->
  <------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] ---------
  -------------------- COOKIE-ECHO -------------------->
  <-------------------- COOKIE-ACK ---------------------

RFC4895 says that each endpoint therefore knows its own random
number and the peer's random number *after* the association
has been established. The local and peer's random number along
with the shared key are then part of the secret used for
calculating the HMAC in the AUTH chunk.

Now, in our scenario, we have 2 threads with 1 non-blocking
SEQ_PACKET socket each, setting up common shared SCTP_AUTH_KEY
and SCTP_AUTH_ACTIVE_KEY properly, and each of them calling
sctp_bindx(3), listen(2) and connect(2) against each other,
thus the handshake looks similar to this, e.g.:

  ---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ---------->
  <------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] ---------
  <--------- INIT[RANDOM; CHUNKS; HMAC-ALGO] -----------
  -------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] -------->
  ...

Since such collisions can also happen with verification tags,
the RFC4895 for AUTH rather vaguely says under section 6.1:

  In case of INIT collision, the rules governing the handling
  of this Random Number follow the same pattern as those for
  the Verification Tag, as explained in Section 5.2.4 of
  RFC 2960 [5]. Therefore, each endpoint knows its own Random
  Number and the peer's Random Number after the association
  has been established.

In RFC2960, section 5.2.4, we're eventually hitting Action B:

  B) In this case, both sides may be attempting to start an
     association at about the same time but the peer endpoint
     started its INIT after responding to the local endpoint's
     INIT. Thus it may have picked a new Verification Tag not
     being aware of the previous Tag it had sent this endpoint.
     The endpoint should stay in or enter the ESTABLISHED
     state but it MUST update its peer's Verification Tag from
     the State Cookie, stop any init or cookie timers that may
     running and send a COOKIE ACK.

In other words, the handling of the Random parameter is the
same as behavior for the Verification Tag as described in
Action B of section 5.2.4.

Looking at the code, we exactly hit the sctp_sf_do_dupcook_b()
case which triggers an SCTP_CMD_UPDATE_ASSOC command to the
side effect interpreter, and in fact it properly copies over
peer_{random, hmacs, chunks} parameters from the newly created
association to update the existing one.

Also, the old asoc_shared_key is being released and based on
the new params, sctp_auth_asoc_init_active_key() updated.
However, the issue observed in this case is that the previous
asoc->peer.auth_capable was 0, and has *not* been updated, so
that instead of creating a new secret, we're doing an early
return from the function sctp_auth_asoc_init_active_key()
leaving asoc->asoc_shared_key as NULL. However, we now have to
authenticate chunks from the updated chunk list (e.g. COOKIE-ACK).

That in fact causes the server side when responding with ...

  <------------------ AUTH; COOKIE-ACK -----------------

... to trigger a NULL pointer dereference, since in
sctp_packet_transmit(), it discovers that an AUTH chunk is
being queued for xmit, and thus it calls sctp_auth_calculate_hmac().

Since the asoc->active_key_id is still inherited from the
endpoint, and the same as encoded into the chunk, it uses
asoc->asoc_shared_key, which is still NULL, as an asoc_key
and dereferences it in ...

  crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len)

... causing an oops. All this happens because sctp_make_cookie_ack()
called with the *new* association has the peer.auth_capable=1
and therefore marks the chunk with auth=1 after checking
sctp_auth_send_cid(), but it is *actually* sent later on over
the then *updated* association's transport that didn't initialize
its shared key due to peer.auth_capable=0. Since control chunks
in that case are not sent by the temporary association which
are scheduled for deletion, they are issued for xmit via
SCTP_CMD_REPLY in the interpreter with the context of the
*updated* association. peer.auth_capable was 0 in the updated
association (which went from COOKIE_WAIT into ESTABLISHED state),
since all previous processing that performed sctp_process_init()
was being done on temporary associations, that we eventually
throw away each time.

The correct fix is to update to the new peer.auth_capable
value as well in the collision case via sctp_assoc_update(),
so that in case the collision migrated from 0 -> 1,
sctp_auth_asoc_init_active_key() can properly recalculate
the secret. This therefore fixes the observed server panic.

Fixes: 730fc3d05cd4 ("[SCTP]: Implete SCTP-AUTH parameter processing")
Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2014-5077
CWE: CWE-476
Vulnerability description: The sctp_assoc_update function in net/sctp/associola.c in the Linux kernel through 3.15.8, when SCTP authentication is enabled, allows remote attackers to cause a denial of service (NULL pointer dereference and OOPS) by starting to establish an association between two endpoints immediately after an exchange of INIT and INIT ACK chunks to establish an earlier association between these endpoints in the opposite direction.

Project: net
File: associola.c

void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
{
	struct sctp_chunk *ack;
	struct sctp_chunk *tmp;

	/* We can remove all the entries from the queue up to
	 * the "Peer-Sequence-Number".
	 */
	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
				transmitted_list) {
		if (ack->subh.addip_hdr->serial ==
				htonl(asoc->peer.addip_serial))
			break;

		list_del_init(&ack->transmitted_list);
		sctp_chunk_free(ack);
	}
}

Project: net
File: associola.c

static u8 sctp_trans_score(const struct sctp_transport *trans)
{
	return sctp_trans_state_to_prio_map[trans->state];
}

Project: net
File: associola.c

int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
					 struct sctp_cookie *cookie,
					 gfp_t gfp)
{
	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
	int var_size3 = cookie->raw_addr_list_len;
	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;

	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
				      asoc->ep->base.bind_addr.port, gfp);
}

Project: net
File: associola.c

void sctp_assoc_update_retran_path(struct sctp_association *asoc)
{
	struct sctp_transport *trans = asoc->peer.retran_path;
	struct sctp_transport *trans_next = NULL;

	/* We're done as we only have the one and only path. */
	if (asoc->peer.transport_count == 1)
		return;
	/* If active_path and retran_path are the same and active,
	 * then this is the only active path. Use it.
	 */
	if (asoc->peer.active_path == asoc->peer.retran_path &&
	    asoc->peer.active_path->state == SCTP_ACTIVE)
		return;

	/* Iterate from retran_path's successor back to retran_path. */
	for (trans = list_next_entry(trans, transports); 1;
	     trans = list_next_entry(trans, transports)) {
		/* Manually skip the head element. */
		if (&trans->transports == &asoc->peer.transport_addr_list)
			continue;
		if (trans->state == SCTP_UNCONFIRMED)
			continue;
		trans_next = sctp_trans_elect_best(trans, trans_next);
		/* Active is good enough for immediate return. */
		if (trans_next->state == SCTP_ACTIVE)
			break;
		/* We've reached the end, time to update path. */
		if (trans == asoc->peer.retran_path)
			break;
	}

	asoc->peer.retran_path = trans_next;

	pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
		 __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
}

Project: net
File: associola.c

void sctp_assoc_rm_peer(struct sctp_association *asoc,
			struct sctp_transport *peer)
{
	struct list_head	*pos;
	struct sctp_transport	*transport;

	pr_debug("%s: association:%p addr:%pISpc\n",
		 __func__, asoc, &peer->ipaddr.sa);

	/* If we are to remove the current retran_path, update it
	 * to the next peer before removing this peer from the list.
	 */
	if (asoc->peer.retran_path == peer)
		sctp_assoc_update_retran_path(asoc);

	/* Remove this peer from the list. */
	list_del_rcu(&peer->transports);

	/* Get the first transport of asoc. */
	pos = asoc->peer.transport_addr_list.next;
	transport = list_entry(pos, struct sctp_transport, transports);

	/* Update any entries that match the peer to be deleted. */
	if (asoc->peer.primary_path == peer)
		sctp_assoc_set_primary(asoc, transport);
	if (asoc->peer.active_path == peer)
		asoc->peer.active_path = transport;
	if (asoc->peer.retran_path == peer)
		asoc->peer.retran_path = transport;
	if (asoc->peer.last_data_from == peer)
		asoc->peer.last_data_from = transport;

	/* If we remove the transport an INIT was last sent to, set it to
	 * NULL. Combined with the update of the retran path above, this
	 * will cause the next INIT to be sent to the next available
	 * transport, maintaining the cycle.
	 */
	if (asoc->init_last_sent_to == peer)
		asoc->init_last_sent_to = NULL;

	/* If we remove the transport an SHUTDOWN was last sent to, set it
	 * to NULL. Combined with the update of the retran path above, this
	 * will cause the next SHUTDOWN to be sent to the next available
	 * transport, maintaining the cycle.
	 */
	if (asoc->shutdown_last_sent_to == peer)
		asoc->shutdown_last_sent_to = NULL;

	/* If we remove the transport an ASCONF was last sent to, set it to
	 * NULL.
	 */
	if (asoc->addip_last_asconf &&
	    asoc->addip_last_asconf->transport == peer)
		asoc->addip_last_asconf->transport = NULL;

	/* If we have something on the transmitted list, we have to
	 * save it off.  The best place is the active path.
	 */
	if (!list_empty(&peer->transmitted)) {
		struct sctp_transport *active = asoc->peer.active_path;
		struct sctp_chunk *ch;

		/* Reset the transport of each chunk on this list */
		list_for_each_entry(ch, &peer->transmitted,
					transmitted_list) {
			ch->transport = NULL;
			ch->rtt_in_progress = 0;
		}

		list_splice_tail_init(&peer->transmitted,
					&active->transmitted);

		/* Start a T3 timer here in case it wasn't running so
		 * that these migrated packets have a chance to get
		 * retransmitted.
		 */
		if (!timer_pending(&active->T3_rtx_timer))
			if (!mod_timer(&active->T3_rtx_timer,
					jiffies + active->rto))
				sctp_transport_hold(active);
	}

	asoc->peer.transport_count--;

	sctp_transport_free(peer);
}

Project: net
File: associola.c

struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
{
	if (!asoc->need_ecne)
		return NULL;

	/* Send ECNE if needed.
	 * Not being able to allocate a chunk here is not deadly.
	 */
	return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
}

Project: net
File: associola.c

void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
				     struct sctp_transport *primary)
{
	struct sctp_transport	*temp;
	struct sctp_transport	*t;

	list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
				 transports) {
		/* if the current transport is not the primary one, delete it */
		if (t != primary)
			sctp_assoc_rm_peer(asoc, t);
	}
}

Project: net
File: associola.c

struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
					     __u32 tsn)
{
	struct sctp_transport *active;
	struct sctp_transport *match;
	struct sctp_transport *transport;
	struct sctp_chunk *chunk;
	__be32 key = htonl(tsn);

	match = NULL;

	/*
	 * FIXME: In general, find a more efficient data structure for
	 * searching.
	 */

	/*
	 * The general strategy is to search each transport's transmitted
	 * list.   Return which transport this TSN lives on.
	 *
	 * Let's be hopeful and check the active_path first.
	 * Another optimization would be to know if there is only one
	 * outbound path and not have to look for the TSN at all.
	 *
	 */

	active = asoc->peer.active_path;

	list_for_each_entry(chunk, &active->transmitted,
			transmitted_list) {

		if (key == chunk->subh.data_hdr->tsn) {
			match = active;
			goto out;
		}
	}

	/* If not found, go search all the other transports. */
	list_for_each_entry(transport, &asoc->peer.transport_addr_list,
			transports) {

		if (transport == active)
			continue;
		list_for_each_entry(chunk, &transport->transmitted,
				transmitted_list) {
			if (key == chunk->subh.data_hdr->tsn) {
				match = transport;
				goto out;
			}
		}
	}
out:
	return match;
}

Project: net
File: associola.c

static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
{
	struct sctp_chunk *asconf;
	struct sctp_chunk *tmp;

	list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
		list_del_init(&asconf->list);
		sctp_chunk_free(asconf);
	}
}

Project: net
File: associola.c

struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
					 const struct sock *sk,
					 sctp_scope_t scope,
					 gfp_t gfp)
{
	struct sctp_association *asoc;

	asoc = kzalloc(sizeof(*asoc), gfp);
	if (!asoc)
		goto fail;

	if (!sctp_association_init(asoc, ep, sk, scope, gfp))
		goto fail_init;

	SCTP_DBG_OBJCNT_INC(assoc);

	pr_debug("Created asoc %p\n", asoc);

	return asoc;

fail_init:
	kfree(asoc);
fail:
	return NULL;
}

Project: net
File: associola.c

int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
			    const union sctp_addr *laddr)
{
	int found = 0;

	if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
	    sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
				 sctp_sk(asoc->base.sk)))
		found = 1;

	return found;
}

Project: net
File: associola.c

static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
					  const struct sctp_endpoint *ep,
					  const struct sock *sk,
					  sctp_scope_t scope,
					  gfp_t gfp)
{
	struct net *net = sock_net(sk);
	struct sctp_sock *sp;
	int i;
	sctp_paramhdr_t *p;
	int err;

	/* Retrieve the SCTP per socket area.  */
	sp = sctp_sk((struct sock *)sk);

	/* Discarding const is appropriate here.  */
	asoc->ep = (struct sctp_endpoint *)ep;
	asoc->base.sk = (struct sock *)sk;

	sctp_endpoint_hold(asoc->ep);
	sock_hold(asoc->base.sk);

	/* Initialize the common base substructure.  */
	asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;

	/* Initialize the object handling fields.  */
	atomic_set(&asoc->base.refcnt, 1);

	/* Initialize the bind addr area.  */
	sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);

	asoc->state = SCTP_STATE_CLOSED;
	asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
	asoc->user_frag = sp->user_frag;

	/* Set the association max_retrans and RTO values from the
	 * socket values.
	 */
	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
	asoc->pf_retrans  = net->sctp.pf_retrans;

	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
	asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);

	/* Initialize the association's heartbeat interval based on the
	 * sock configured value.
	 */
	asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);

	/* Initialize path max retrans value. */
	asoc->pathmaxrxt = sp->pathmaxrxt;

	/* Initialize default path MTU. */
	asoc->pathmtu = sp->pathmtu;

	/* Set association default SACK delay */
	asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
	asoc->sackfreq = sp->sackfreq;

	/* Set the association default flags controlling
	 * Heartbeat, SACK delay, and Path MTU Discovery.
	 */
	asoc->param_flags = sp->param_flags;

	/* Initialize the maximum number of new data packets that can be sent
	 * in a burst.
	 */
	asoc->max_burst = sp->max_burst;

	/* initialize association timers */
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;

	/* sctpimpguide Section 2.12.2
	 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
	 * recommended value of 5 times 'RTO.Max'.
	 */
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
		= 5 * asoc->rto_max;

	asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;

	/* Initializes the timers */
	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
		setup_timer(&asoc->timers[i], sctp_timer_events[i],
				(unsigned long)asoc);

	/* Pull default initialization values from the sock options.
	 * Note: This assumes that the values have already been
	 * validated in the sock.
	 */
	asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
	asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
	asoc->max_init_attempts	= sp->initmsg.sinit_max_attempts;

	asoc->max_init_timeo =
		 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);

	/* Set the local window size for receive.
	 * This is also the rcvbuf space per association.
	 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
	 * 1500 bytes in one SCTP packet.
	 */
	if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
		asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
	else
		asoc->rwnd = sk->sk_rcvbuf/2;

	asoc->a_rwnd = asoc->rwnd;

	/* Use my own max window until I learn something better.  */
	asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;

	/* Initialize the receive memory counter */
	atomic_set(&asoc->rmem_alloc, 0);

	init_waitqueue_head(&asoc->wait);

	asoc->c.my_vtag = sctp_generate_tag(ep);
	asoc->c.my_port = ep->base.bind_addr.port;

	asoc->c.initial_tsn = sctp_generate_tsn(ep);

	asoc->next_tsn = asoc->c.initial_tsn;

	asoc->ctsn_ack_point = asoc->next_tsn - 1;
	asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
	asoc->highest_sacked = asoc->ctsn_ack_point;
	asoc->last_cwr_tsn = asoc->ctsn_ack_point;

	/* ADDIP Section 4.1 Asconf Chunk Procedures
	 *
	 * When an endpoint has an ASCONF signaled change to be sent to the
	 * remote endpoint it should do the following:
	 * ...
	 * A2) a serial number should be assigned to the chunk. The serial
	 * number SHOULD be a monotonically increasing number. The serial
	 * numbers SHOULD be initialized at the start of the
	 * association to the same value as the initial TSN.
	 */
	asoc->addip_serial = asoc->c.initial_tsn;

	INIT_LIST_HEAD(&asoc->addip_chunk_list);
	INIT_LIST_HEAD(&asoc->asconf_ack_list);

	/* Make an empty list of remote transport addresses.  */
	INIT_LIST_HEAD(&asoc->peer.transport_addr_list);

	/* RFC 2960 5.1 Normal Establishment of an Association
	 *
	 * After the reception of the first data chunk in an
	 * association the endpoint must immediately respond with a
	 * sack to acknowledge the data chunk.  Subsequent
	 * acknowledgements should be done as described in Section
	 * 6.2.
	 *
	 * [We implement this by telling a new association that it
	 * already received one packet.]
	 */
	asoc->peer.sack_needed = 1;
	asoc->peer.sack_generation = 1;

	/* Assume that the peer will tell us if he recognizes ASCONF
	 * as part of INIT exchange.
	 * The sctp_addip_noauth option is there for backward compatibility
	 * and will revert old behavior.
	 */
	if (net->sctp.addip_noauth)
		asoc->peer.asconf_capable = 1;

	/* Create an input queue.  */
	sctp_inq_init(&asoc->base.inqueue);
	sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);

	/* Create an output queue.  */
	sctp_outq_init(asoc, &asoc->outqueue);

	if (!sctp_ulpq_init(&asoc->ulpq, asoc))
		goto fail_init;

	/* Assume that peer would support both address types unless we are
	 * told otherwise.
	 */
	asoc->peer.ipv4_address = 1;
	if (asoc->base.sk->sk_family == PF_INET6)
		asoc->peer.ipv6_address = 1;
	INIT_LIST_HEAD(&asoc->asocs);

	asoc->default_stream = sp->default_stream;
	asoc->default_ppid = sp->default_ppid;
	asoc->default_flags = sp->default_flags;
	asoc->default_context = sp->default_context;
	asoc->default_timetolive = sp->default_timetolive;
	asoc->default_rcv_context = sp->default_rcv_context;

	/* AUTH related initializations */
	INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
	err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
	if (err)
		goto fail_init;

	asoc->active_key_id = ep->active_key_id;

	/* Save the hmacs and chunks list into this association */
	if (ep->auth_hmacs_list)
		memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
			ntohs(ep->auth_hmacs_list->param_hdr.length));
	if (ep->auth_chunk_list)
		memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
			ntohs(ep->auth_chunk_list->param_hdr.length));

	/* Get the AUTH random number for this association */
	p = (sctp_paramhdr_t *)asoc->c.auth_random;
	p->type = SCTP_PARAM_RANDOM;
	p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
	get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);

	return asoc;

fail_init:
	sock_put(asoc->base.sk);
	sctp_endpoint_put(asoc->ep);
	return NULL;
}

Project: net
File: associola.c

static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
{
	struct net *net = sock_net(asoc->base.sk);
	switch (asoc->state) {
	case SCTP_STATE_ESTABLISHED:
	case SCTP_STATE_SHUTDOWN_PENDING:
	case SCTP_STATE_SHUTDOWN_RECEIVED:
	case SCTP_STATE_SHUTDOWN_SENT:
		if ((asoc->rwnd > asoc->a_rwnd) &&
		    ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
			   (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
			   asoc->pathmtu)))
			return true;
		break;
	default:
		break;
	}
	return false;
}

Project: net
File: associola.c

static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
						   struct sctp_transport *trans2)
{
	if (trans1->error_count > trans2->error_count) {
		return trans2;
	} else if (trans1->error_count == trans2->error_count &&
		   ktime_after(trans2->last_time_heard,
			       trans1->last_time_heard)) {
		return trans2;
	} else {
		return trans1;
	}
}

Project: net
File: associola.c

sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
				  struct sctp_transport *last_sent_to)
{
	/* If this is the first time packet is sent, use the active path,
	 * else use the retran path. If the last packet was sent over the
	 * retran path, update the retran path and use it.
	 */
	if (last_sent_to == NULL) {
		return asoc->peer.active_path;
	} else {
		if (last_sent_to == asoc->peer.retran_path)
			sctp_assoc_update_retran_path(asoc);

		return asoc->peer.retran_path;
	}
}

Project: net
File: associola.c

static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
{
	struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
	struct sctp_transport *trans_pf = NULL;

	/* Look for the two most recently used active transports. */
	list_for_each_entry(trans, &asoc->peer.transport_addr_list,
			    transports) {
		/* Skip uninteresting transports. */
		if (trans->state == SCTP_INACTIVE ||
		    trans->state == SCTP_UNCONFIRMED)
			continue;
		/* Keep track of the best PF transport from our
		 * list in case we don't find an active one.
		 */
		if (trans->state == SCTP_PF) {
			trans_pf = sctp_trans_elect_best(trans, trans_pf);
			continue;
		}
		/* For active transports, pick the most recent ones. */
		if (trans_pri == NULL ||
		    ktime_after(trans->last_time_heard,
				trans_pri->last_time_heard)) {
			trans_sec = trans_pri;
			trans_pri = trans;
		} else if (trans_sec == NULL ||
			   ktime_after(trans->last_time_heard,
				       trans_sec->last_time_heard)) {
			trans_sec = trans;
		}
	}

	/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
	 *
	 * By default, an endpoint should always transmit to the primary
	 * path, unless the SCTP user explicitly specifies the
	 * destination transport address (and possibly source transport
	 * address) to use. [If the primary is active but not most recent,
	 * bump the most recently used transport.]
	 */
	if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
	     asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
	     asoc->peer.primary_path != trans_pri) {
		trans_sec = trans_pri;
		trans_pri = asoc->peer.primary_path;
	}

	/* We did not find anything useful for a possible retransmission
	 * path; either primary path that we found is the the same as
	 * the current one, or we didn't generally find an active one.
	 */
	if (trans_sec == NULL)
		trans_sec = trans_pri;

	/* If we failed to find a usable transport, just camp on the
	 * primary or retran, even if they are inactive, if possible
	 * pick a PF iff it's the better choice.
	 */
	if (trans_pri == NULL) {
		trans_pri = sctp_trans_elect_best(asoc->peer.primary_path,
						  asoc->peer.retran_path);
		trans_pri = sctp_trans_elect_best(trans_pri, trans_pf);
		trans_sec = asoc->peer.primary_path;
	}

	/* Set the active and retran transports. */
	asoc->peer.active_path = trans_pri;
	asoc->peer.retran_path = trans_sec;
}

Project: net
File: associola.c

void sctp_association_free(struct sctp_association *asoc)
{
	struct sock *sk = asoc->base.sk;
	struct sctp_transport *transport;
	struct list_head *pos, *temp;
	int i;

	/* Only real associations count against the endpoint, so
	 * don't bother for if this is a temporary association.
	 */
	if (!list_empty(&asoc->asocs)) {
		list_del(&asoc->asocs);

		/* Decrement the backlog value for a TCP-style listening
		 * socket.
		 */
		if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
			sk->sk_ack_backlog--;
	}

	/* Mark as dead, so other users can know this structure is
	 * going away.
	 */
	asoc->base.dead = true;

	/* Dispose of any data lying around in the outqueue. */
	sctp_outq_free(&asoc->outqueue);

	/* Dispose of any pending messages for the upper layer. */
	sctp_ulpq_free(&asoc->ulpq);

	/* Dispose of any pending chunks on the inqueue. */
	sctp_inq_free(&asoc->base.inqueue);

	sctp_tsnmap_free(&asoc->peer.tsn_map);

	/* Free ssnmap storage. */
	sctp_ssnmap_free(asoc->ssnmap);

	/* Clean up the bound address list. */
	sctp_bind_addr_free(&asoc->base.bind_addr);

	/* Do we need to go through all of our timers and
	 * delete them?   To be safe we will try to delete all, but we
	 * should be able to go through and make a guess based
	 * on our state.
	 */
	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
		if (del_timer(&asoc->timers[i]))
			sctp_association_put(asoc);
	}

	/* Free peer's cached cookie. */
	kfree(asoc->peer.cookie);
	kfree(asoc->peer.peer_random);
	kfree(asoc->peer.peer_chunks);
	kfree(asoc->peer.peer_hmacs);

	/* Release the transport structures. */
	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
		transport = list_entry(pos, struct sctp_transport, transports);
		list_del_rcu(pos);
		sctp_transport_free(transport);
	}

	asoc->peer.transport_count = 0;

	sctp_asconf_queue_teardown(asoc);

	/* Free pending address space being deleted */
	if (asoc->asconf_addr_del_pending != NULL)
		kfree(asoc->asconf_addr_del_pending);

	/* AUTH - Free the endpoint shared keys */
	sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);

	/* AUTH - Free the association shared key */
	sctp_auth_key_put(asoc->asoc_shared_key);

	sctp_association_put(asoc);
}

Project: net
File: associola.c

void sctp_assoc_set_primary(struct sctp_association *asoc,
			    struct sctp_transport *transport)
{
	int changeover = 0;

	/* it's a changeover only if we already have a primary path
	 * that we are changing
	 */
	if (asoc->peer.primary_path != NULL &&
	    asoc->peer.primary_path != transport)
		changeover = 1 ;

	asoc->peer.primary_path = transport;

	/* Set a default msg_name for events. */
	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
	       sizeof(union sctp_addr));

	/* If the primary path is changing, assume that the
	 * user wants to use this new path.
	 */
	if ((transport->state == SCTP_ACTIVE) ||
	    (transport->state == SCTP_UNKNOWN))
		asoc->peer.active_path = transport;

	/*
	 * SFR-CACC algorithm:
	 * Upon the receipt of a request to change the primary
	 * destination address, on the data structure for the new
	 * primary destination, the sender MUST do the following:
	 *
	 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
	 * to this destination address earlier. The sender MUST set
	 * CYCLING_CHANGEOVER to indicate that this switch is a
	 * double switch to the same destination address.
	 *
	 * Really, only bother is we have data queued or outstanding on
	 * the association.
	 */
	if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
		return;

	if (transport->cacc.changeover_active)
		transport->cacc.cycling_changeover = changeover;

	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
	 * a changeover has occurred.
	 */
	transport->cacc.changeover_active = changeover;

	/* 3) The sender MUST store the next TSN to be sent in
	 * next_tsn_at_change.
	 */
	transport->cacc.next_tsn_at_change = asoc->next_tsn;
}

Project: net
File: associola.c

struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
					   struct net *net,
					   const union sctp_addr *laddr,
					   const union sctp_addr *paddr)
{
	struct sctp_transport *transport;

	if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
	    (htons(asoc->peer.port) == paddr->v4.sin_port) &&
	    net_eq(sock_net(asoc->base.sk), net)) {
		transport = sctp_assoc_lookup_paddr(asoc, paddr);
		if (!transport)
			goto out;

		if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
					 sctp_sk(asoc->base.sk)))
			goto out;
	}
	transport = NULL;

out:
	return transport;
}

Project: net
File: associola.c

void sctp_assoc_control_transport(struct sctp_association *asoc,
				  struct sctp_transport *transport,
				  sctp_transport_cmd_t command,
				  sctp_sn_error_t error)
{
	struct sctp_ulpevent *event;
	struct sockaddr_storage addr;
	int spc_state = 0;
	bool ulp_notify = true;

	/* Record the transition on the transport.  */
	switch (command) {
	case SCTP_TRANSPORT_UP:
		/* If we are moving from UNCONFIRMED state due
		 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
		 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
		 */
		if (SCTP_UNCONFIRMED == transport->state &&
		    SCTP_HEARTBEAT_SUCCESS == error)
			spc_state = SCTP_ADDR_CONFIRMED;
		else
			spc_state = SCTP_ADDR_AVAILABLE;
		/* Don't inform ULP about transition from PF to
		 * active state and set cwnd to 1 MTU, see SCTP
		 * Quick failover draft section 5.1, point 5
		 */
		if (transport->state == SCTP_PF) {
			ulp_notify = false;
			transport->cwnd = asoc->pathmtu;
		}
		transport->state = SCTP_ACTIVE;
		break;

	case SCTP_TRANSPORT_DOWN:
		/* If the transport was never confirmed, do not transition it
		 * to inactive state.  Also, release the cached route since
		 * there may be a better route next time.
		 */
		if (transport->state != SCTP_UNCONFIRMED)
			transport->state = SCTP_INACTIVE;
		else {
			dst_release(transport->dst);
			transport->dst = NULL;
		}

		spc_state = SCTP_ADDR_UNREACHABLE;
		break;

	case SCTP_TRANSPORT_PF:
		transport->state = SCTP_PF;
		ulp_notify = false;
		break;

	default:
		return;
	}

	/* Generate and send a SCTP_PEER_ADDR_CHANGE notification
	 * to the user.
	 */
	if (ulp_notify) {
		memset(&addr, 0, sizeof(struct sockaddr_storage));
		memcpy(&addr, &transport->ipaddr,
		       transport->af_specific->sockaddr_len);

		event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
					0, spc_state, error, GFP_ATOMIC);
		if (event)
			sctp_ulpq_tail_event(&asoc->ulpq, event);
	}

	/* Select new active and retran paths. */
	sctp_select_active_and_retran_path(asoc);
}

Project: net
File: associola.c

void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
{
	int rx_count;
	int over = 0;

	if (unlikely(!asoc->rwnd || asoc->rwnd_over))
		pr_debug("%s: association:%p has asoc->rwnd:%u, "
			 "asoc->rwnd_over:%u!\n", __func__, asoc,
			 asoc->rwnd, asoc->rwnd_over);

	if (asoc->ep->rcvbuf_policy)
		rx_count = atomic_read(&asoc->rmem_alloc);
	else
		rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);

	/* If we've reached or overflowed our receive buffer, announce
	 * a 0 rwnd if rwnd would still be positive.  Store the
	 * the potential pressure overflow so that the window can be restored
	 * back to original value.
	 */
	if (rx_count >= asoc->base.sk->sk_rcvbuf)
		over = 1;

	if (asoc->rwnd >= len) {
		asoc->rwnd -= len;
		if (over) {
			asoc->rwnd_press += asoc->rwnd;
			asoc->rwnd = 0;
		}
	} else {
		asoc->rwnd_over = len - asoc->rwnd;
		asoc->rwnd = 0;
	}

	pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
		 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
		 asoc->rwnd_press);
}

Project: net
File: associola.c

void sctp_asconf_queue_teardown(struct sctp_association *asoc)
{
	/* Free any cached ASCONF_ACK chunk. */
	sctp_assoc_free_asconf_acks(asoc);

	/* Free the ASCONF queue. */
	sctp_assoc_free_asconf_queue(asoc);

	/* Free any cached ASCONF chunk. */
	if (asoc->addip_last_asconf)
		sctp_chunk_free(asoc->addip_last_asconf);
}

Project: net
File: associola.c

void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
{
	struct sctp_sock *newsp = sctp_sk(newsk);
	struct sock *oldsk = assoc->base.sk;

	/* Delete the association from the old endpoint's list of
	 * associations.
	 */
	list_del_init(&assoc->asocs);

	/* Decrement the backlog value for a TCP-style socket. */
	if (sctp_style(oldsk, TCP))
		oldsk->sk_ack_backlog--;

	/* Release references to the old endpoint and the sock.  */
	sctp_endpoint_put(assoc->ep);
	sock_put(assoc->base.sk);

	/* Get a reference to the new endpoint.  */
	assoc->ep = newsp->ep;
	sctp_endpoint_hold(assoc->ep);

	/* Get a reference to the new sock.  */
	assoc->base.sk = newsk;
	sock_hold(assoc->base.sk);

	/* Add the association to the new endpoint's list of associations.  */
	sctp_endpoint_add_asoc(newsp->ep, assoc);
}

Project: net
File: associola.c

int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
{
	bool preload = !!(gfp & __GFP_WAIT);
	int ret;

	/* If the id is already assigned, keep it. */
	if (asoc->assoc_id)
		return 0;

	if (preload)
		idr_preload(gfp);
	spin_lock_bh(&sctp_assocs_id_lock);
	/* 0 is not a valid assoc_id, must be >= 1 */
	ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, 1, 0, GFP_NOWAIT);
	spin_unlock_bh(&sctp_assocs_id_lock);
	if (preload)
		idr_preload_end();
	if (ret < 0)
		return ret;

	asoc->assoc_id = (sctp_assoc_t)ret;
	return 0;
}

Project: net
File: associola.c

void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
{
	struct sctp_chunk *sack;
	struct timer_list *timer;

	if (asoc->rwnd_over) {
		if (asoc->rwnd_over >= len) {
			asoc->rwnd_over -= len;
		} else {
			asoc->rwnd += (len - asoc->rwnd_over);
			asoc->rwnd_over = 0;
		}
	} else {
		asoc->rwnd += len;
	}

	/* If we had window pressure, start recovering it
	 * once our rwnd had reached the accumulated pressure
	 * threshold.  The idea is to recover slowly, but up
	 * to the initial advertised window.
	 */
	if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
		int change = min(asoc->pathmtu, asoc->rwnd_press);
		asoc->rwnd += change;
		asoc->rwnd_press -= change;
	}

	pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
		 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
		 asoc->a_rwnd);

	/* Send a window update SACK if the rwnd has increased by at least the
	 * minimum of the association's PMTU and half of the receive buffer.
	 * The algorithm used is similar to the one described in
	 * Section 4.2.3.3 of RFC 1122.
	 */
	if (sctp_peer_needs_update(asoc)) {
		asoc->a_rwnd = asoc->rwnd;

		pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
			 "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
			 asoc->a_rwnd);

		sack = sctp_make_sack(asoc);
		if (!sack)
			return;

		asoc->peer.sack_needed = 0;

		sctp_outq_tail(&asoc->outqueue, sack);

		/* Stop the SACK timer.  */
		timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
		if (del_timer(timer))
			sctp_association_put(asoc);
	}
}

Project: net
File: associola.c

static void sctp_association_destroy(struct sctp_association *asoc)
{
	if (unlikely(!asoc->base.dead)) {
		WARN(1, "Attempt to destroy undead association %p!\n", asoc);
		return;
	}

	sctp_endpoint_put(asoc->ep);
	sock_put(asoc->base.sk);

	if (asoc->assoc_id != 0) {
		spin_lock_bh(&sctp_assocs_id_lock);
		idr_remove(&sctp_assocs_id, asoc->assoc_id);
		spin_unlock_bh(&sctp_assocs_id_lock);
	}

	WARN_ON(atomic_read(&asoc->rmem_alloc));

	kfree(asoc);
	SCTP_DBG_OBJCNT_DEC(assoc);
}

Project: net
File: associola.c

void sctp_association_hold(struct sctp_association *asoc)
{
	atomic_inc(&asoc->base.refcnt);
}

Project: net
File: associola.c

void sctp_association_put(struct sctp_association *asoc)
{
	if (atomic_dec_and_test(&asoc->base.refcnt))
		sctp_association_destroy(asoc);
}

Project: net
File: associola.c

__u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
{
	/* From Section 1.6 Serial Number Arithmetic:
	 * Transmission Sequence Numbers wrap around when they reach
	 * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
	 * after transmitting TSN = 2*32 - 1 is TSN = 0.
	 */
	__u32 retval = asoc->next_tsn;
	asoc->next_tsn++;
	asoc->unack_data++;

	return retval;
}

Project: net
File: associola.c

void sctp_assoc_sync_pmtu(struct sock *sk, struct sctp_association *asoc)
{
	struct sctp_transport *t;
	__u32 pmtu = 0;

	if (!asoc)
		return;

	/* Get the lowest pmtu of all the transports. */
	list_for_each_entry(t, &asoc->peer.transport_addr_list,
				transports) {
		if (t->pmtu_pending && t->dst) {
			sctp_transport_update_pmtu(sk, t, dst_mtu(t->dst));
			t->pmtu_pending = 0;
		}
		if (!pmtu || (t->pathmtu < pmtu))
			pmtu = t->pathmtu;
	}

	if (pmtu) {
		asoc->pathmtu = pmtu;
		asoc->frag_point = sctp_frag_point(asoc, pmtu);
	}

	pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
		 asoc->pathmtu, asoc->frag_point);
}

Project: net
File: associola.c

static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
{
	struct sctp_chunk *ack;
	struct sctp_chunk *tmp;

	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
				transmitted_list) {
		list_del_init(&ack->transmitted_list);
		sctp_chunk_free(ack);
	}
}

Project: net
File: associola.c

struct sctp_transport *sctp_assoc_lookup_paddr(
					const struct sctp_association *asoc,
					const union sctp_addr *address)
{
	struct sctp_transport *t;

	/* Cycle through all transports searching for a peer address. */

	list_for_each_entry(t, &asoc->peer.transport_addr_list,
			transports) {
		if (sctp_cmp_addr_exact(address, &t->ipaddr))
			return t;
	}

	return NULL;
}

Project: net
File: associola.c

struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
					   const union sctp_addr *addr,
					   const gfp_t gfp,
					   const int peer_state)
{
	struct net *net = sock_net(asoc->base.sk);
	struct sctp_transport *peer;
	struct sctp_sock *sp;
	unsigned short port;

	sp = sctp_sk(asoc->base.sk);

	/* AF_INET and AF_INET6 share common port field. */
	port = ntohs(addr->v4.sin_port);

	pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
		 asoc, &addr->sa, peer_state);

	/* Set the port if it has not been set yet.  */
	if (0 == asoc->peer.port)
		asoc->peer.port = port;

	/* Check to see if this is a duplicate. */
	peer = sctp_assoc_lookup_paddr(asoc, addr);
	if (peer) {
		/* An UNKNOWN state is only set on transports added by
		 * user in sctp_connectx() call.  Such transports should be
		 * considered CONFIRMED per RFC 4960, Section 5.4.
		 */
		if (peer->state == SCTP_UNKNOWN) {
			peer->state = SCTP_ACTIVE;
		}
		return peer;
	}

	peer = sctp_transport_new(net, addr, gfp);
	if (!peer)
		return NULL;

	sctp_transport_set_owner(peer, asoc);

	/* Initialize the peer's heartbeat interval based on the
	 * association configured value.
	 */
	peer->hbinterval = asoc->hbinterval;

	/* Set the path max_retrans.  */
	peer->pathmaxrxt = asoc->pathmaxrxt;

	/* And the partial failure retrans threshold */
	peer->pf_retrans = asoc->pf_retrans;

	/* Initialize the peer's SACK delay timeout based on the
	 * association configured value.
	 */
	peer->sackdelay = asoc->sackdelay;
	peer->sackfreq = asoc->sackfreq;

	/* Enable/disable heartbeat, SACK delay, and path MTU discovery
	 * based on association setting.
	 */
	peer->param_flags = asoc->param_flags;

	sctp_transport_route(peer, NULL, sp);

	/* Initialize the pmtu of the transport. */
	if (peer->param_flags & SPP_PMTUD_DISABLE) {
		if (asoc->pathmtu)
			peer->pathmtu = asoc->pathmtu;
		else
			peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
	}

	/* If this is the first transport addr on this association,
	 * initialize the association PMTU to the peer's PMTU.
	 * If not and the current association PMTU is higher than the new
	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
	 */
	if (asoc->pathmtu)
		asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
	else
		asoc->pathmtu = peer->pathmtu;

	pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
		 asoc->pathmtu);

	peer->pmtu_pending = 0;

	asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);

	/* The asoc->peer.port might not be meaningful yet, but
	 * initialize the packet structure anyway.
	 */
	sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
			 asoc->peer.port);

	/* 7.2.1 Slow-Start
	 *
	 * o The initial cwnd before DATA transmission or after a sufficiently
	 *   long idle period MUST be set to
	 *      min(4*MTU, max(2*MTU, 4380 bytes))
	 *
	 * o The initial value of ssthresh MAY be arbitrarily high
	 *   (for example, implementations MAY use the size of the
	 *   receiver advertised window).
	 */
	peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));

	/* At this point, we may not have the receiver's advertised window,
	 * so initialize ssthresh to the default value and it will be set
	 * later when we process the INIT.
	 */
	peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;

	peer->partial_bytes_acked = 0;
	peer->flight_size = 0;
	peer->burst_limited = 0;

	/* Set the transport's RTO.initial value */
	peer->rto = asoc->rto_initial;
	sctp_max_rto(asoc, peer);

	/* Set the peer's active state. */
	peer->state = peer_state;

	/* Attach the remote transport to our asoc.  */
	list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
	asoc->peer.transport_count++;

	/* If we do not yet have a primary path, set one.  */
	if (!asoc->peer.primary_path) {
		sctp_assoc_set_primary(asoc, peer);
		asoc->peer.retran_path = peer;
	}

	if (asoc->peer.active_path == asoc->peer.retran_path &&
	    peer->state != SCTP_UNCONFIRMED) {
		asoc->peer.retran_path = peer;
	}

	return peer;
}

Project: net
File: associola.c

int sctp_cmp_addr_exact(const union sctp_addr *ss1,
			const union sctp_addr *ss2)
{
	struct sctp_af *af;

	af = sctp_get_af_specific(ss1->sa.sa_family);
	if (unlikely(!af))
		return 0;

	return af->cmp_addr(ss1, ss2);
}

Project: net
File: associola.c

void sctp_assoc_del_peer(struct sctp_association *asoc,
			 const union sctp_addr *addr)
{
	struct list_head	*pos;
	struct list_head	*temp;
	struct sctp_transport	*transport;

	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
		transport = list_entry(pos, struct sctp_transport, transports);
		if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
			/* Do book keeping for removing the peer and free it. */
			sctp_assoc_rm_peer(asoc, transport);
			break;
		}
	}
}

Project: net
File: associola.c

int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
				     sctp_scope_t scope, gfp_t gfp)
{
	int flags;

	/* Use scoping rules to determine the subset of addresses from
	 * the endpoint.
	 */
	flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
	if (asoc->peer.ipv4_address)
		flags |= SCTP_ADDR4_PEERSUPP;
	if (asoc->peer.ipv6_address)
		flags |= SCTP_ADDR6_PEERSUPP;

	return sctp_bind_addr_copy(sock_net(asoc->base.sk),
				   &asoc->base.bind_addr,
				   &asoc->ep->base.bind_addr,
				   scope, gfp, flags);
}

Project: net
File: associola.c

static void sctp_assoc_bh_rcv(struct work_struct *work)
{
	struct sctp_association *asoc =
		container_of(work, struct sctp_association,
			     base.inqueue.immediate);
	struct net *net = sock_net(asoc->base.sk);
	struct sctp_endpoint *ep;
	struct sctp_chunk *chunk;
	struct sctp_inq *inqueue;
	int state;
	sctp_subtype_t subtype;
	int error = 0;

	/* The association should be held so we should be safe. */
	ep = asoc->ep;

	inqueue = &asoc->base.inqueue;
	sctp_association_hold(asoc);
	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
		state = asoc->state;
		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);

		/* SCTP-AUTH, Section 6.3:
		 *    The receiver has a list of chunk types which it expects
		 *    to be received only after an AUTH-chunk.  This list has
		 *    been sent to the peer during the association setup.  It
		 *    MUST silently discard these chunks if they are not placed
		 *    after an AUTH chunk in the packet.
		 */
		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
			continue;

		/* Remember where the last DATA chunk came from so we
		 * know where to send the SACK.
		 */
		if (sctp_chunk_is_data(chunk))
			asoc->peer.last_data_from = chunk->transport;
		else {
			SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
			asoc->stats.ictrlchunks++;
			if (chunk->chunk_hdr->type == SCTP_CID_SACK)
				asoc->stats.isacks++;
		}

		if (chunk->transport)
			chunk->transport->last_time_heard = ktime_get();

		/* Run through the state machine. */
		error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
				   state, ep, asoc, chunk, GFP_ATOMIC);

		/* Check to see if the association is freed in response to
		 * the incoming chunk.  If so, get out of the while loop.
		 */
		if (asoc->base.dead)
			break;

		/* If there is an error on chunk, discard this packet. */
		if (error && chunk)
			chunk->pdiscard = 1;
	}
	sctp_association_put(asoc);
}

Project: net
File: associola.c

static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
						    struct sctp_transport *best)
{
	u8 score_curr, score_best;

	if (best == NULL)
		return curr;

	score_curr = sctp_trans_score(curr);
	score_best = sctp_trans_score(best);

	/* First, try a score-based selection if both transport states
	 * differ. If we're in a tie, lets try to make a more clever
	 * decision here based on error counts and last time heard.
	 */
	if (score_curr > score_best)
		return curr;
	else if (score_curr == score_best)
		return sctp_trans_elect_tie(curr, best);
	else
		return best;
}