input.c 32.5 KB
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/* SCTP kernel implementation
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 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001-2003 International Business Machines, Corp.
 * Copyright (c) 2001 Intel Corp.
 * Copyright (c) 2001 Nokia, Inc.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 *
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 * This file is part of the SCTP kernel implementation
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 *
 * These functions handle all input from the IP layer into SCTP.
 *
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 * This SCTP implementation is free software;
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 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
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 * This SCTP implementation is distributed in the hope that it
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 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
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 * along with GNU CC; see the file COPYING.  If not, see
 * <http://www.gnu.org/licenses/>.
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 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
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 *    lksctp developers <linux-sctp@vger.kernel.org>
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 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Karl Knutson <karl@athena.chicago.il.us>
 *    Xingang Guo <xingang.guo@intel.com>
 *    Jon Grimm <jgrimm@us.ibm.com>
 *    Hui Huang <hui.huang@nokia.com>
 *    Daisy Chang <daisyc@us.ibm.com>
 *    Sridhar Samudrala <sri@us.ibm.com>
 *    Ardelle Fan <ardelle.fan@intel.com>
 */

#include <linux/types.h>
#include <linux/list.h> /* For struct list_head */
#include <linux/socket.h>
#include <linux/ip.h>
#include <linux/time.h> /* For struct timeval */
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#include <linux/slab.h>
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#include <net/ip.h>
#include <net/icmp.h>
#include <net/snmp.h>
#include <net/sock.h>
#include <net/xfrm.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
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#include <net/sctp/checksum.h>
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#include <net/net_namespace.h>
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/* Forward declarations for internal helpers. */
static int sctp_rcv_ootb(struct sk_buff *);
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static struct sctp_association *__sctp_rcv_lookup(struct net *net,
				      struct sk_buff *skb,
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				      const union sctp_addr *paddr,
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				      const union sctp_addr *laddr,
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				      struct sctp_transport **transportp);
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static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
						const union sctp_addr *laddr);
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static struct sctp_association *__sctp_lookup_association(
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					struct net *net,
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					const union sctp_addr *local,
					const union sctp_addr *peer,
					struct sctp_transport **pt);

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static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
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/* Calculate the SCTP checksum of an SCTP packet.  */
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static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
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{
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	struct sctphdr *sh = sctp_hdr(skb);
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	__le32 cmp = sh->checksum;
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	__le32 val = sctp_compute_cksum(skb, 0);
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	if (val != cmp) {
		/* CRC failure, dump it. */
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		__SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
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		return -1;
	}
	return 0;
}

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struct sctp_input_cb {
	union {
		struct inet_skb_parm	h4;
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#if IS_ENABLED(CONFIG_IPV6)
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		struct inet6_skb_parm	h6;
#endif
	} header;
	struct sctp_chunk *chunk;
};
#define SCTP_INPUT_CB(__skb)	((struct sctp_input_cb *)&((__skb)->cb[0]))

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/*
 * This is the routine which IP calls when receiving an SCTP packet.
 */
int sctp_rcv(struct sk_buff *skb)
{
	struct sock *sk;
	struct sctp_association *asoc;
	struct sctp_endpoint *ep = NULL;
	struct sctp_ep_common *rcvr;
	struct sctp_transport *transport = NULL;
	struct sctp_chunk *chunk;
	struct sctphdr *sh;
	union sctp_addr src;
	union sctp_addr dest;
	int family;
	struct sctp_af *af;
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	struct net *net = dev_net(skb->dev);
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	if (skb->pkt_type != PACKET_HOST)
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		goto discard_it;

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	__SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
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	if (skb_linearize(skb))
		goto discard_it;

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	sh = sctp_hdr(skb);
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	/* Pull up the IP and SCTP headers. */
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	__skb_pull(skb, skb_transport_offset(skb));
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	if (skb->len < sizeof(struct sctphdr))
		goto discard_it;
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	skb->csum_valid = 0; /* Previous value not applicable */
	if (skb_csum_unnecessary(skb))
		__skb_decr_checksum_unnecessary(skb);
	else if (!sctp_checksum_disable && sctp_rcv_checksum(net, skb) < 0)
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		goto discard_it;
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	skb->csum_valid = 1;
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	skb_pull(skb, sizeof(struct sctphdr));

	/* Make sure we at least have chunk headers worth of data left. */
	if (skb->len < sizeof(struct sctp_chunkhdr))
		goto discard_it;

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	family = ipver2af(ip_hdr(skb)->version);
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	af = sctp_get_af_specific(family);
	if (unlikely(!af))
		goto discard_it;

	/* Initialize local addresses for lookups. */
	af->from_skb(&src, skb, 1);
	af->from_skb(&dest, skb, 0);

	/* If the packet is to or from a non-unicast address,
	 * silently discard the packet.
	 *
	 * This is not clearly defined in the RFC except in section
	 * 8.4 - OOTB handling.  However, based on the book "Stream Control
	 * Transmission Protocol" 2.1, "It is important to note that the
	 * IP address of an SCTP transport address must be a routable
	 * unicast address.  In other words, IP multicast addresses and
	 * IP broadcast addresses cannot be used in an SCTP transport
	 * address."
	 */
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	if (!af->addr_valid(&src, NULL, skb) ||
	    !af->addr_valid(&dest, NULL, skb))
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		goto discard_it;

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	asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
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	if (!asoc)
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		ep = __sctp_rcv_lookup_endpoint(net, &dest);
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	/* Retrieve the common input handling substructure. */
	rcvr = asoc ? &asoc->base : &ep->base;
	sk = rcvr->sk;

	/*
	 * If a frame arrives on an interface and the receiving socket is
	 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
	 */
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	if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) {
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		if (asoc) {
			sctp_association_put(asoc);
			asoc = NULL;
		} else {
			sctp_endpoint_put(ep);
			ep = NULL;
		}
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		sk = net->sctp.ctl_sock;
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		ep = sctp_sk(sk)->ep;
		sctp_endpoint_hold(ep);
		rcvr = &ep->base;
	}

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	/*
	 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
	 * An SCTP packet is called an "out of the blue" (OOTB)
	 * packet if it is correctly formed, i.e., passed the
	 * receiver's checksum check, but the receiver is not
	 * able to identify the association to which this
	 * packet belongs.
	 */
	if (!asoc) {
		if (sctp_rcv_ootb(skb)) {
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			__SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
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			goto discard_release;
		}
	}

	if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
		goto discard_release;
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	nf_reset(skb);
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	if (sk_filter(sk, skb))
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		goto discard_release;
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	/* Create an SCTP packet structure. */
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	chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
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	if (!chunk)
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		goto discard_release;
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	SCTP_INPUT_CB(skb)->chunk = chunk;
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	/* Remember what endpoint is to handle this packet. */
	chunk->rcvr = rcvr;

	/* Remember the SCTP header. */
	chunk->sctp_hdr = sh;

	/* Set the source and destination addresses of the incoming chunk.  */
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	sctp_init_addrs(chunk, &src, &dest);
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	/* Remember where we came from.  */
	chunk->transport = transport;

	/* Acquire access to the sock lock. Note: We are safe from other
	 * bottom halves on this lock, but a user may be in the lock too,
	 * so check if it is busy.
	 */
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	bh_lock_sock(sk);
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	if (sk != rcvr->sk) {
		/* Our cached sk is different from the rcvr->sk.  This is
		 * because migrate()/accept() may have moved the association
		 * to a new socket and released all the sockets.  So now we
		 * are holding a lock on the old socket while the user may
		 * be doing something with the new socket.  Switch our veiw
		 * of the current sk.
		 */
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		bh_unlock_sock(sk);
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		sk = rcvr->sk;
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		bh_lock_sock(sk);
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	}

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	if (sock_owned_by_user(sk)) {
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		if (sctp_add_backlog(sk, skb)) {
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			bh_unlock_sock(sk);
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			sctp_chunk_free(chunk);
			skb = NULL; /* sctp_chunk_free already freed the skb */
			goto discard_release;
		}
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		__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG);
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	} else {
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		__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ);
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		sctp_inq_push(&chunk->rcvr->inqueue, chunk);
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	}
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	bh_unlock_sock(sk);
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	/* Release the asoc/ep ref we took in the lookup calls. */
	if (asoc)
		sctp_association_put(asoc);
	else
		sctp_endpoint_put(ep);
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	return 0;
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discard_it:
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	__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
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	kfree_skb(skb);
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	return 0;
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discard_release:
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	/* Release the asoc/ep ref we took in the lookup calls. */
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	if (asoc)
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		sctp_association_put(asoc);
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	else
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		sctp_endpoint_put(ep);

	goto discard_it;
}

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/* Process the backlog queue of the socket.  Every skb on
 * the backlog holds a ref on an association or endpoint.
 * We hold this ref throughout the state machine to make
 * sure that the structure we need is still around.
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 */
int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
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	struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
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	struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
	struct sctp_ep_common *rcvr = NULL;
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	int backloged = 0;
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	rcvr = chunk->rcvr;
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	/* If the rcvr is dead then the association or endpoint
	 * has been deleted and we can safely drop the chunk
	 * and refs that we are holding.
	 */
	if (rcvr->dead) {
		sctp_chunk_free(chunk);
		goto done;
	}

	if (unlikely(rcvr->sk != sk)) {
		/* In this case, the association moved from one socket to
		 * another.  We are currently sitting on the backlog of the
		 * old socket, so we need to move.
		 * However, since we are here in the process context we
		 * need to take make sure that the user doesn't own
		 * the new socket when we process the packet.
		 * If the new socket is user-owned, queue the chunk to the
		 * backlog of the new socket without dropping any refs.
		 * Otherwise, we can safely push the chunk on the inqueue.
		 */

		sk = rcvr->sk;
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		bh_lock_sock(sk);
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		if (sock_owned_by_user(sk)) {
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			if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
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				sctp_chunk_free(chunk);
			else
				backloged = 1;
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		} else
			sctp_inq_push(inqueue, chunk);

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		bh_unlock_sock(sk);
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		/* If the chunk was backloged again, don't drop refs */
		if (backloged)
			return 0;
	} else {
		sctp_inq_push(inqueue, chunk);
	}

done:
	/* Release the refs we took in sctp_add_backlog */
	if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
		sctp_association_put(sctp_assoc(rcvr));
	else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
		sctp_endpoint_put(sctp_ep(rcvr));
	else
		BUG();

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	return 0;
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}

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static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
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{
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	struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
	struct sctp_ep_common *rcvr = chunk->rcvr;
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	int ret;
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	ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
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	if (!ret) {
		/* Hold the assoc/ep while hanging on the backlog queue.
		 * This way, we know structures we need will not disappear
		 * from us
		 */
		if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
			sctp_association_hold(sctp_assoc(rcvr));
		else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
			sctp_endpoint_hold(sctp_ep(rcvr));
		else
			BUG();
	}
	return ret;
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}

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/* Handle icmp frag needed error. */
void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
			   struct sctp_transport *t, __u32 pmtu)
{
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	if (!t || (t->pathmtu <= pmtu))
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		return;

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	if (sock_owned_by_user(sk)) {
		asoc->pmtu_pending = 1;
		t->pmtu_pending = 1;
		return;
	}

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	if (t->param_flags & SPP_PMTUD_ENABLE) {
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		/* Update transports view of the MTU */
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		sctp_transport_update_pmtu(sk, t, pmtu);
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		/* Update association pmtu. */
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		sctp_assoc_sync_pmtu(sk, asoc);
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	}
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	/* Retransmit with the new pmtu setting.
	 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
	 * Needed will never be sent, but if a message was sent before
	 * PMTU discovery was disabled that was larger than the PMTU, it
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	 * would not be fragmented, so it must be re-transmitted fragmented.
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	 */
	sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
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}

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void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
			struct sk_buff *skb)
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{
	struct dst_entry *dst;

	if (!t)
		return;
	dst = sctp_transport_dst_check(t);
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	if (dst)
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		dst->ops->redirect(dst, sk, skb);
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}

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/*
 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
 *
 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
 *        or a "Protocol Unreachable" treat this message as an abort
 *        with the T bit set.
 *
 * This function sends an event to the state machine, which will abort the
 * association.
 *
 */
void sctp_icmp_proto_unreachable(struct sock *sk,
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			   struct sctp_association *asoc,
			   struct sctp_transport *t)
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{
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	if (sock_owned_by_user(sk)) {
		if (timer_pending(&t->proto_unreach_timer))
			return;
		else {
			if (!mod_timer(&t->proto_unreach_timer,
						jiffies + (HZ/20)))
				sctp_association_hold(asoc);
		}
	} else {
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		struct net *net = sock_net(sk);

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		pr_debug("%s: unrecognized next header type "
			 "encountered!\n", __func__);

459
		if (del_timer(&t->proto_unreach_timer))
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			sctp_association_put(asoc);
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		sctp_do_sm(net, SCTP_EVENT_T_OTHER,
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			   SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
			   asoc->state, asoc->ep, asoc, t,
			   GFP_ATOMIC);
	}
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}

/* Common lookup code for icmp/icmpv6 error handler. */
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struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
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			     struct sctphdr *sctphdr,
			     struct sctp_association **app,
			     struct sctp_transport **tpp)
{
	union sctp_addr saddr;
	union sctp_addr daddr;
	struct sctp_af *af;
	struct sock *sk = NULL;
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	struct sctp_association *asoc;
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	struct sctp_transport *transport = NULL;
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	struct sctp_init_chunk *chunkhdr;
	__u32 vtag = ntohl(sctphdr->vtag);
	int len = skb->len - ((void *)sctphdr - (void *)skb->data);
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	*app = NULL; *tpp = NULL;
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	af = sctp_get_af_specific(family);
	if (unlikely(!af)) {
		return NULL;
	}

	/* Initialize local addresses for lookups. */
	af->from_skb(&saddr, skb, 1);
	af->from_skb(&daddr, skb, 0);

	/* Look for an association that matches the incoming ICMP error
	 * packet.
	 */
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	asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
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	if (!asoc)
		return NULL;
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	sk = asoc->base.sk;
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	/* RFC 4960, Appendix C. ICMP Handling
	 *
	 * ICMP6) An implementation MUST validate that the Verification Tag
	 * contained in the ICMP message matches the Verification Tag of
	 * the peer.  If the Verification Tag is not 0 and does NOT
	 * match, discard the ICMP message.  If it is 0 and the ICMP
	 * message contains enough bytes to verify that the chunk type is
	 * an INIT chunk and that the Initiate Tag matches the tag of the
	 * peer, continue with ICMP7.  If the ICMP message is too short
	 * or the chunk type or the Initiate Tag does not match, silently
	 * discard the packet.
	 */
	if (vtag == 0) {
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		chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
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		if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
			  + sizeof(__be32) ||
		    chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
		    ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
			goto out;
		}
	} else if (vtag != asoc->c.peer_vtag) {
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		goto out;
	}
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	bh_lock_sock(sk);
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	/* If too many ICMPs get dropped on busy
	 * servers this needs to be solved differently.
	 */
	if (sock_owned_by_user(sk))
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		__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
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	*app = asoc;
	*tpp = transport;
	return sk;

out:
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	sctp_association_put(asoc);
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	return NULL;
}

/* Common cleanup code for icmp/icmpv6 error handler. */
547
void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
L
Linus Torvalds 已提交
548
{
549
	bh_unlock_sock(sk);
550
	sctp_association_put(asoc);
L
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551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569
}

/*
 * This routine is called by the ICMP module when it gets some
 * sort of error condition.  If err < 0 then the socket should
 * be closed and the error returned to the user.  If err > 0
 * it's just the icmp type << 8 | icmp code.  After adjustment
 * header points to the first 8 bytes of the sctp header.  We need
 * to find the appropriate port.
 *
 * The locking strategy used here is very "optimistic". When
 * someone else accesses the socket the ICMP is just dropped
 * and for some paths there is no check at all.
 * A more general error queue to queue errors for later handling
 * is probably better.
 *
 */
void sctp_v4_err(struct sk_buff *skb, __u32 info)
{
570
	const struct iphdr *iph = (const struct iphdr *)skb->data;
571
	const int ihlen = iph->ihl * 4;
572 573
	const int type = icmp_hdr(skb)->type;
	const int code = icmp_hdr(skb)->code;
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Linus Torvalds 已提交
574
	struct sock *sk;
575
	struct sctp_association *asoc = NULL;
L
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576 577
	struct sctp_transport *transport;
	struct inet_sock *inet;
578
	__u16 saveip, savesctp;
L
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579
	int err;
580
	struct net *net = dev_net(skb->dev);
L
Linus Torvalds 已提交
581 582

	/* Fix up skb to look at the embedded net header. */
583 584
	saveip = skb->network_header;
	savesctp = skb->transport_header;
585
	skb_reset_network_header(skb);
586
	skb_set_transport_header(skb, ihlen);
587
	sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
588
	/* Put back, the original values. */
589 590
	skb->network_header = saveip;
	skb->transport_header = savesctp;
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591
	if (!sk) {
E
Eric Dumazet 已提交
592
		__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
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593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608
		return;
	}
	/* Warning:  The sock lock is held.  Remember to call
	 * sctp_err_finish!
	 */

	switch (type) {
	case ICMP_PARAMETERPROB:
		err = EPROTO;
		break;
	case ICMP_DEST_UNREACH:
		if (code > NR_ICMP_UNREACH)
			goto out_unlock;

		/* PMTU discovery (RFC1191) */
		if (ICMP_FRAG_NEEDED == code) {
609 610
			sctp_icmp_frag_needed(sk, asoc, transport,
					      WORD_TRUNC(info));
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Linus Torvalds 已提交
611
			goto out_unlock;
612
		} else {
L
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613
			if (ICMP_PROT_UNREACH == code) {
614
				sctp_icmp_proto_unreachable(sk, asoc,
L
Linus Torvalds 已提交
615 616 617 618 619 620 621 622 623 624 625 626 627 628 629
							    transport);
				goto out_unlock;
			}
		}
		err = icmp_err_convert[code].errno;
		break;
	case ICMP_TIME_EXCEEDED:
		/* Ignore any time exceeded errors due to fragment reassembly
		 * timeouts.
		 */
		if (ICMP_EXC_FRAGTIME == code)
			goto out_unlock;

		err = EHOSTUNREACH;
		break;
630 631
	case ICMP_REDIRECT:
		sctp_icmp_redirect(sk, transport, skb);
632
		/* Fall through to out_unlock. */
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633 634 635 636 637 638 639 640 641 642 643 644 645
	default:
		goto out_unlock;
	}

	inet = inet_sk(sk);
	if (!sock_owned_by_user(sk) && inet->recverr) {
		sk->sk_err = err;
		sk->sk_error_report(sk);
	} else {  /* Only an error on timeout */
		sk->sk_err_soft = err;
	}

out_unlock:
646
	sctp_err_finish(sk, asoc);
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647 648 649 650 651 652 653 654 655 656 657 658 659 660
}

/*
 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 *
 * This function scans all the chunks in the OOTB packet to determine if
 * the packet should be discarded right away.  If a response might be needed
 * for this packet, or, if further processing is possible, the packet will
 * be queued to a proper inqueue for the next phase of handling.
 *
 * Output:
 * Return 0 - If further processing is needed.
 * Return 1 - If the packet can be discarded right away.
 */
661
static int sctp_rcv_ootb(struct sk_buff *skb)
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Linus Torvalds 已提交
662 663 664 665 666 667 668
{
	sctp_chunkhdr_t *ch;
	__u8 *ch_end;

	ch = (sctp_chunkhdr_t *) skb->data;

	/* Scan through all the chunks in the packet.  */
669 670 671 672 673 674
	do {
		/* Break out if chunk length is less then minimal. */
		if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
			break;

		ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
675
		if (ch_end > skb_tail_pointer(skb))
676
			break;
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677 678 679 680 681 682 683 684 685 686 687 688 689 690 691

		/* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
		 * receiver MUST silently discard the OOTB packet and take no
		 * further action.
		 */
		if (SCTP_CID_ABORT == ch->type)
			goto discard;

		/* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
		 * chunk, the receiver should silently discard the packet
		 * and take no further action.
		 */
		if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
			goto discard;

692 693 694 695 696 697 698 699
		/* RFC 4460, 2.11.2
		 * This will discard packets with INIT chunk bundled as
		 * subsequent chunks in the packet.  When INIT is first,
		 * the normal INIT processing will discard the chunk.
		 */
		if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
			goto discard;

L
Linus Torvalds 已提交
700
		ch = (sctp_chunkhdr_t *) ch_end;
701
	} while (ch_end < skb_tail_pointer(skb));
L
Linus Torvalds 已提交
702 703 704 705 706 707 708 709 710 711

	return 0;

discard:
	return 1;
}

/* Insert endpoint into the hash table.  */
static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
{
712
	struct net *net = sock_net(ep->base.sk);
L
Linus Torvalds 已提交
713 714 715 716 717
	struct sctp_ep_common *epb;
	struct sctp_hashbucket *head;

	epb = &ep->base;

718
	epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
L
Linus Torvalds 已提交
719 720
	head = &sctp_ep_hashtable[epb->hashent];

721
	write_lock(&head->lock);
722
	hlist_add_head(&epb->node, &head->chain);
723
	write_unlock(&head->lock);
L
Linus Torvalds 已提交
724 725 726 727 728
}

/* Add an endpoint to the hash. Local BH-safe. */
void sctp_hash_endpoint(struct sctp_endpoint *ep)
{
729
	local_bh_disable();
L
Linus Torvalds 已提交
730
	__sctp_hash_endpoint(ep);
731
	local_bh_enable();
L
Linus Torvalds 已提交
732 733 734 735 736
}

/* Remove endpoint from the hash table.  */
static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
{
737
	struct net *net = sock_net(ep->base.sk);
L
Linus Torvalds 已提交
738 739 740 741 742
	struct sctp_hashbucket *head;
	struct sctp_ep_common *epb;

	epb = &ep->base;

743
	epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
L
Linus Torvalds 已提交
744 745 746

	head = &sctp_ep_hashtable[epb->hashent];

747
	write_lock(&head->lock);
748
	hlist_del_init(&epb->node);
749
	write_unlock(&head->lock);
L
Linus Torvalds 已提交
750 751 752 753 754
}

/* Remove endpoint from the hash.  Local BH-safe. */
void sctp_unhash_endpoint(struct sctp_endpoint *ep)
{
755
	local_bh_disable();
L
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756
	__sctp_unhash_endpoint(ep);
757
	local_bh_enable();
L
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758 759 760
}

/* Look up an endpoint. */
761 762
static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
						const union sctp_addr *laddr)
L
Linus Torvalds 已提交
763 764 765 766 767 768
{
	struct sctp_hashbucket *head;
	struct sctp_ep_common *epb;
	struct sctp_endpoint *ep;
	int hash;

769
	hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
L
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770 771
	head = &sctp_ep_hashtable[hash];
	read_lock(&head->lock);
772
	sctp_for_each_hentry(epb, &head->chain) {
L
Linus Torvalds 已提交
773
		ep = sctp_ep(epb);
774
		if (sctp_endpoint_is_match(ep, net, laddr))
L
Linus Torvalds 已提交
775 776 777
			goto hit;
	}

778
	ep = sctp_sk(net->sctp.ctl_sock)->ep;
L
Linus Torvalds 已提交
779 780 781 782 783 784 785

hit:
	sctp_endpoint_hold(ep);
	read_unlock(&head->lock);
	return ep;
}

786 787
/* rhashtable for transport */
struct sctp_hash_cmp_arg {
788
	const struct sctp_endpoint	*ep;
789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805
	const union sctp_addr		*laddr;
	const union sctp_addr		*paddr;
	const struct net		*net;
};

static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
				const void *ptr)
{
	const struct sctp_hash_cmp_arg *x = arg->key;
	const struct sctp_transport *t = ptr;
	struct sctp_association *asoc = t->asoc;
	const struct net *net = x->net;

	if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
		return 1;
	if (!net_eq(sock_net(asoc->base.sk), net))
		return 1;
806 807 808 809 810 811 812 813 814 815
	if (x->ep) {
		if (x->ep != asoc->ep)
			return 1;
	} else {
		if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
			return 1;
		if (!sctp_bind_addr_match(&asoc->base.bind_addr,
					  x->laddr, sctp_sk(asoc->base.sk)))
			return 1;
	}
816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841

	return 0;
}

static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
{
	const struct sctp_transport *t = data;
	const union sctp_addr *paddr = &t->ipaddr;
	const struct net *net = sock_net(t->asoc->base.sk);
	u16 lport = htons(t->asoc->base.bind_addr.port);
	u32 addr;

	if (paddr->sa.sa_family == AF_INET6)
		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
	else
		addr = paddr->v4.sin_addr.s_addr;

	return  jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 |
			     (__force __u32)lport, net_hash_mix(net), seed);
}

static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed)
{
	const struct sctp_hash_cmp_arg *x = data;
	const union sctp_addr *paddr = x->paddr;
	const struct net *net = x->net;
842
	u16 lport;
843 844
	u32 addr;

845 846
	lport = x->ep ? htons(x->ep->base.bind_addr.port) :
			x->laddr->v4.sin_port;
847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877
	if (paddr->sa.sa_family == AF_INET6)
		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
	else
		addr = paddr->v4.sin_addr.s_addr;

	return  jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 |
			     (__force __u32)lport, net_hash_mix(net), seed);
}

static const struct rhashtable_params sctp_hash_params = {
	.head_offset		= offsetof(struct sctp_transport, node),
	.hashfn			= sctp_hash_key,
	.obj_hashfn		= sctp_hash_obj,
	.obj_cmpfn		= sctp_hash_cmp,
	.automatic_shrinking	= true,
};

int sctp_transport_hashtable_init(void)
{
	return rhashtable_init(&sctp_transport_hashtable, &sctp_hash_params);
}

void sctp_transport_hashtable_destroy(void)
{
	rhashtable_destroy(&sctp_transport_hashtable);
}

void sctp_hash_transport(struct sctp_transport *t)
{
	struct sctp_hash_cmp_arg arg;

878 879 880
	if (t->asoc->temp)
		return;

881
	arg.ep = t->asoc->ep;
882 883 884 885 886 887 888 889 890 891 892
	arg.paddr = &t->ipaddr;
	arg.net   = sock_net(t->asoc->base.sk);

reinsert:
	if (rhashtable_lookup_insert_key(&sctp_transport_hashtable, &arg,
					 &t->node, sctp_hash_params) == -EBUSY)
		goto reinsert;
}

void sctp_unhash_transport(struct sctp_transport *t)
{
893 894 895
	if (t->asoc->temp)
		return;

896 897 898 899 900 901 902 903 904 905
	rhashtable_remove_fast(&sctp_transport_hashtable, &t->node,
			       sctp_hash_params);
}

struct sctp_transport *sctp_addrs_lookup_transport(
				struct net *net,
				const union sctp_addr *laddr,
				const union sctp_addr *paddr)
{
	struct sctp_hash_cmp_arg arg = {
906
		.ep    = NULL,
907 908 909 910 911 912 913 914 915 916 917 918 919 920
		.laddr = laddr,
		.paddr = paddr,
		.net   = net,
	};

	return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
				      sctp_hash_params);
}

struct sctp_transport *sctp_epaddr_lookup_transport(
				const struct sctp_endpoint *ep,
				const union sctp_addr *paddr)
{
	struct net *net = sock_net(ep->base.sk);
921 922 923 924 925
	struct sctp_hash_cmp_arg arg = {
		.ep    = ep,
		.paddr = paddr,
		.net   = net,
	};
926

927 928
	return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
				      sctp_hash_params);
929 930
}

L
Linus Torvalds 已提交
931 932
/* Look up an association. */
static struct sctp_association *__sctp_lookup_association(
933
					struct net *net,
L
Linus Torvalds 已提交
934 935 936 937
					const union sctp_addr *local,
					const union sctp_addr *peer,
					struct sctp_transport **pt)
{
938
	struct sctp_transport *t;
939
	struct sctp_association *asoc = NULL;
L
Linus Torvalds 已提交
940

941
	t = sctp_addrs_lookup_transport(net, local, peer);
942 943
	if (!t || !sctp_transport_hold(t))
		goto out;
L
Linus Torvalds 已提交
944

945 946
	asoc = t->asoc;
	sctp_association_hold(asoc);
947
	*pt = t;
L
Linus Torvalds 已提交
948

949 950 951 952
	sctp_transport_put(t);

out:
	return asoc;
L
Linus Torvalds 已提交
953 954
}

955
/* Look up an association. protected by RCU read lock */
956
static
957 958
struct sctp_association *sctp_lookup_association(struct net *net,
						 const union sctp_addr *laddr,
L
Linus Torvalds 已提交
959
						 const union sctp_addr *paddr,
960
						 struct sctp_transport **transportp)
L
Linus Torvalds 已提交
961 962 963
{
	struct sctp_association *asoc;

964
	rcu_read_lock();
965
	asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
966
	rcu_read_unlock();
L
Linus Torvalds 已提交
967 968 969 970 971

	return asoc;
}

/* Is there an association matching the given local and peer addresses? */
972 973
int sctp_has_association(struct net *net,
			 const union sctp_addr *laddr,
L
Linus Torvalds 已提交
974 975 976 977 978
			 const union sctp_addr *paddr)
{
	struct sctp_association *asoc;
	struct sctp_transport *transport;

979
	if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
L
Linus Torvalds 已提交
980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004
		sctp_association_put(asoc);
		return 1;
	}

	return 0;
}

/*
 * SCTP Implementors Guide, 2.18 Handling of address
 * parameters within the INIT or INIT-ACK.
 *
 * D) When searching for a matching TCB upon reception of an INIT
 *    or INIT-ACK chunk the receiver SHOULD use not only the
 *    source address of the packet (containing the INIT or
 *    INIT-ACK) but the receiver SHOULD also use all valid
 *    address parameters contained within the chunk.
 *
 * 2.18.3 Solution description
 *
 * This new text clearly specifies to an implementor the need
 * to look within the INIT or INIT-ACK. Any implementation that
 * does not do this, may not be able to establish associations
 * in certain circumstances.
 *
 */
1005 1006
static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
	struct sk_buff *skb,
L
Linus Torvalds 已提交
1007 1008 1009 1010 1011
	const union sctp_addr *laddr, struct sctp_transport **transportp)
{
	struct sctp_association *asoc;
	union sctp_addr addr;
	union sctp_addr *paddr = &addr;
1012
	struct sctphdr *sh = sctp_hdr(skb);
L
Linus Torvalds 已提交
1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043
	union sctp_params params;
	sctp_init_chunk_t *init;
	struct sctp_transport *transport;
	struct sctp_af *af;

	/*
	 * This code will NOT touch anything inside the chunk--it is
	 * strictly READ-ONLY.
	 *
	 * RFC 2960 3  SCTP packet Format
	 *
	 * Multiple chunks can be bundled into one SCTP packet up to
	 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
	 * COMPLETE chunks.  These chunks MUST NOT be bundled with any
	 * other chunk in a packet.  See Section 6.10 for more details
	 * on chunk bundling.
	 */

	/* Find the start of the TLVs and the end of the chunk.  This is
	 * the region we search for address parameters.
	 */
	init = (sctp_init_chunk_t *)skb->data;

	/* Walk the parameters looking for embedded addresses. */
	sctp_walk_params(params, init, init_hdr.params) {

		/* Note: Ignoring hostname addresses. */
		af = sctp_get_af_specific(param_type2af(params.p->type));
		if (!af)
			continue;

1044
		af->from_addr_param(paddr, params.addr, sh->source, 0);
L
Linus Torvalds 已提交
1045

1046
		asoc = __sctp_lookup_association(net, laddr, paddr, &transport);
L
Linus Torvalds 已提交
1047 1048 1049 1050 1051 1052 1053
		if (asoc)
			return asoc;
	}

	return NULL;
}

1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068
/* ADD-IP, Section 5.2
 * When an endpoint receives an ASCONF Chunk from the remote peer
 * special procedures may be needed to identify the association the
 * ASCONF Chunk is associated with. To properly find the association
 * the following procedures SHOULD be followed:
 *
 * D2) If the association is not found, use the address found in the
 * Address Parameter TLV combined with the port number found in the
 * SCTP common header. If found proceed to rule D4.
 *
 * D2-ext) If more than one ASCONF Chunks are packed together, use the
 * address found in the ASCONF Address Parameter TLV of each of the
 * subsequent ASCONF Chunks. If found, proceed to rule D4.
 */
static struct sctp_association *__sctp_rcv_asconf_lookup(
1069
					struct net *net,
1070 1071
					sctp_chunkhdr_t *ch,
					const union sctp_addr *laddr,
1072
					__be16 peer_port,
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
					struct sctp_transport **transportp)
{
	sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
	struct sctp_af *af;
	union sctp_addr_param *param;
	union sctp_addr paddr;

	/* Skip over the ADDIP header and find the Address parameter */
	param = (union sctp_addr_param *)(asconf + 1);

1083
	af = sctp_get_af_specific(param_type2af(param->p.type));
1084 1085 1086 1087 1088
	if (unlikely(!af))
		return NULL;

	af->from_addr_param(&paddr, param, peer_port, 0);

1089
	return __sctp_lookup_association(net, laddr, &paddr, transportp);
1090 1091 1092
}


1093 1094 1095 1096 1097 1098 1099
/* SCTP-AUTH, Section 6.3:
*    If the receiver does not find a STCB for a packet containing an AUTH
*    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
*    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
*    association.
*
* This means that any chunks that can help us identify the association need
L
Lucas De Marchi 已提交
1100
* to be looked at to find this association.
1101
*/
1102 1103
static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
				      struct sk_buff *skb,
1104 1105 1106
				      const union sctp_addr *laddr,
				      struct sctp_transport **transportp)
{
1107 1108 1109 1110 1111 1112 1113 1114
	struct sctp_association *asoc = NULL;
	sctp_chunkhdr_t *ch;
	int have_auth = 0;
	unsigned int chunk_num = 1;
	__u8 *ch_end;

	/* Walk through the chunks looking for AUTH or ASCONF chunks
	 * to help us find the association.
1115
	 */
1116 1117 1118 1119 1120 1121 1122 1123 1124 1125
	ch = (sctp_chunkhdr_t *) skb->data;
	do {
		/* Break out if chunk length is less then minimal. */
		if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
			break;

		ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
		if (ch_end > skb_tail_pointer(skb))
			break;

1126
		switch (ch->type) {
1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150
		case SCTP_CID_AUTH:
			have_auth = chunk_num;
			break;

		case SCTP_CID_COOKIE_ECHO:
			/* If a packet arrives containing an AUTH chunk as
			 * a first chunk, a COOKIE-ECHO chunk as the second
			 * chunk, and possibly more chunks after them, and
			 * the receiver does not have an STCB for that
			 * packet, then authentication is based on
			 * the contents of the COOKIE- ECHO chunk.
			 */
			if (have_auth == 1 && chunk_num == 2)
				return NULL;
			break;

		case SCTP_CID_ASCONF:
			if (have_auth || net->sctp.addip_noauth)
				asoc = __sctp_rcv_asconf_lookup(
						net, ch, laddr,
						sctp_hdr(skb)->source,
						transportp);
		default:
			break;
1151 1152 1153 1154 1155 1156 1157 1158 1159 1160
		}

		if (asoc)
			break;

		ch = (sctp_chunkhdr_t *) ch_end;
		chunk_num++;
	} while (ch_end < skb_tail_pointer(skb));

	return asoc;
1161 1162 1163 1164 1165 1166 1167 1168
}

/*
 * There are circumstances when we need to look inside the SCTP packet
 * for information to help us find the association.   Examples
 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
 * chunks.
 */
1169 1170
static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
				      struct sk_buff *skb,
1171 1172 1173 1174 1175 1176 1177
				      const union sctp_addr *laddr,
				      struct sctp_transport **transportp)
{
	sctp_chunkhdr_t *ch;

	ch = (sctp_chunkhdr_t *) skb->data;

1178 1179 1180 1181 1182 1183 1184 1185
	/* The code below will attempt to walk the chunk and extract
	 * parameter information.  Before we do that, we need to verify
	 * that the chunk length doesn't cause overflow.  Otherwise, we'll
	 * walk off the end.
	 */
	if (WORD_ROUND(ntohs(ch->length)) > skb->len)
		return NULL;

1186
	/* If this is INIT/INIT-ACK look inside the chunk too. */
1187
	if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1188
		return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1189

1190
	return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1191 1192
}

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/* Lookup an association for an inbound skb. */
1194 1195
static struct sctp_association *__sctp_rcv_lookup(struct net *net,
				      struct sk_buff *skb,
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				      const union sctp_addr *paddr,
				      const union sctp_addr *laddr,
				      struct sctp_transport **transportp)
{
	struct sctp_association *asoc;

1202
	asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
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	/* Further lookup for INIT/INIT-ACK packets.
	 * SCTP Implementors Guide, 2.18 Handling of address
	 * parameters within the INIT or INIT-ACK.
	 */
	if (!asoc)
1209
		asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
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	return asoc;
}