text: /* SCTP kernel implementation
   * Copyright (c) 1999-2000 Cisco, Inc.
   * Copyright (c) 1999-2001 Motorola, Inc.
   * Copyright (c) 2001-2002 International Business Machines, Corp.
   * Copyright (c) 2001 Intel Corp.
   * Copyright (c) 2001 Nokia, Inc.
   * Copyright (c) 2001 La Monte H.P. Yarroll
   *
   * This file is part of the SCTP kernel implementation
   *
   * This abstraction represents an SCTP endpoint.
   *
   * The SCTP implementation is free software;
   * 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.
   *
   * The SCTP implementation is distributed in the hope that it
   * 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
   * along with GNU CC; see the file COPYING.  If not, see
   * <http://www.gnu.org/licenses/>.
   *
   * Please send any bug reports or fixes you make to the
   * email address(es):
   *    lksctp developers <linux-sctp@vger.kernel.org>
   *
   * Written or modified by:
   *    La Monte H.P. Yarroll <piggy@acm.org>
   *    Karl Knutson <karl@athena.chicago.il.us>
   *    Jon Grimm <jgrimm@austin.ibm.com>
   *    Daisy Chang <daisyc@us.ibm.com>
   *    Dajiang Zhang <dajiang.zhang@nokia.com>
   */
  
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/in.h>
  #include <linux/random.h>	/* get_random_bytes() */
  #include <linux/crypto.h>
  #include <net/sock.h>
  #include <net/ipv6.h>
  #include <net/sctp/sctp.h>
  #include <net/sctp/sm.h>
  
  /* Forward declarations for internal helpers. */
  static void sctp_endpoint_bh_rcv(struct work_struct *work);
  
  /*
   * Initialize the base fields of the endpoint structure.
   */
  static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep,
  						struct sock *sk,
  						gfp_t gfp)
  {
  	struct net *net = sock_net(sk);
  	struct sctp_hmac_algo_param *auth_hmacs = NULL;
  	struct sctp_chunks_param *auth_chunks = NULL;
  	struct sctp_shared_key *null_key;
  	int err;
  
  	ep->digest = kzalloc(SCTP_SIGNATURE_SIZE, gfp);
  	if (!ep->digest)
  		return NULL;
  
  	ep->auth_enable = net->sctp.auth_enable;
  	if (ep->auth_enable) {
  		/* Allocate space for HMACS and CHUNKS authentication
  		 * variables.  There are arrays that we encode directly
  		 * into parameters to make the rest of the operations easier.
  		 */
  		auth_hmacs = kzalloc(sizeof(sctp_hmac_algo_param_t) +
  				sizeof(__u16) * SCTP_AUTH_NUM_HMACS, gfp);
  		if (!auth_hmacs)
  			goto nomem;
  
  		auth_chunks = kzalloc(sizeof(sctp_chunks_param_t) +
  					SCTP_NUM_CHUNK_TYPES, gfp);
  		if (!auth_chunks)
  			goto nomem;
  
  		/* Initialize the HMACS parameter.
  		 * SCTP-AUTH: Section 3.3
  		 *    Every endpoint supporting SCTP chunk authentication MUST
  		 *    support the HMAC based on the SHA-1 algorithm.
  		 */
  		auth_hmacs->param_hdr.type = SCTP_PARAM_HMAC_ALGO;
  		auth_hmacs->param_hdr.length =
  					htons(sizeof(sctp_paramhdr_t) + 2);
  		auth_hmacs->hmac_ids[0] = htons(SCTP_AUTH_HMAC_ID_SHA1);
  
  		/* Initialize the CHUNKS parameter */
  		auth_chunks->param_hdr.type = SCTP_PARAM_CHUNKS;
  		auth_chunks->param_hdr.length = htons(sizeof(sctp_paramhdr_t));
  
  		/* If the Add-IP functionality is enabled, we must
  		 * authenticate, ASCONF and ASCONF-ACK chunks
  		 */
  		if (net->sctp.addip_enable) {
  			auth_chunks->chunks[0] = SCTP_CID_ASCONF;
  			auth_chunks->chunks[1] = SCTP_CID_ASCONF_ACK;
  			auth_chunks->param_hdr.length =
  					htons(sizeof(sctp_paramhdr_t) + 2);
  		}
  	}
  
  	/* Initialize the base structure. */
  	/* What type of endpoint are we?  */
  	ep->base.type = SCTP_EP_TYPE_SOCKET;
  
  	/* Initialize the basic object fields. */
  	atomic_set(&ep->base.refcnt, 1);
  	ep->base.dead = false;
  
  	/* Create an input queue.  */
  	sctp_inq_init(&ep->base.inqueue);
  
  	/* Set its top-half handler */
  	sctp_inq_set_th_handler(&ep->base.inqueue, sctp_endpoint_bh_rcv);
  
  	/* Initialize the bind addr area */
  	sctp_bind_addr_init(&ep->base.bind_addr, 0);
  
  	/* Create the lists of associations.  */
  	INIT_LIST_HEAD(&ep->asocs);
  
  	/* Use SCTP specific send buffer space queues.  */
  	ep->sndbuf_policy = net->sctp.sndbuf_policy;
  
  	sk->sk_data_ready = sctp_data_ready;
  	sk->sk_write_space = sctp_write_space;
  	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
  
  	/* Get the receive buffer policy for this endpoint */
  	ep->rcvbuf_policy = net->sctp.rcvbuf_policy;
  
  	/* Initialize the secret key used with cookie. */
  	get_random_bytes(ep->secret_key, sizeof(ep->secret_key));
  
  	/* SCTP-AUTH extensions*/
  	INIT_LIST_HEAD(&ep->endpoint_shared_keys);
  	null_key = sctp_auth_shkey_create(0, gfp);
  	if (!null_key)
  		goto nomem;
  
  	list_add(&null_key->key_list, &ep->endpoint_shared_keys);
  
  	/* Allocate and initialize transorms arrays for supported HMACs. */
  	err = sctp_auth_init_hmacs(ep, gfp);
  	if (err)
  		goto nomem_hmacs;
  
  	/* Add the null key to the endpoint shared keys list and
  	 * set the hmcas and chunks pointers.
  	 */
  	ep->auth_hmacs_list = auth_hmacs;
  	ep->auth_chunk_list = auth_chunks;
  
  	/* Remember who we are attached to.  */
  	ep->base.sk = sk;
  	sock_hold(ep->base.sk);
  
  	return ep;
  
  nomem_hmacs:
  	sctp_auth_destroy_keys(&ep->endpoint_shared_keys);
  nomem:
  	/* Free all allocations */
  	kfree(auth_hmacs);
  	kfree(auth_chunks);
  	kfree(ep->digest);
  	return NULL;
  
  }
  
  /* Create a sctp_endpoint with all that boring stuff initialized.
   * Returns NULL if there isn't enough memory.
   */
  struct sctp_endpoint *sctp_endpoint_new(struct sock *sk, gfp_t gfp)
  {
  	struct sctp_endpoint *ep;
  
  	/* Build a local endpoint. */
  	ep = kzalloc(sizeof(*ep), gfp);
  	if (!ep)
  		goto fail;
  
  	if (!sctp_endpoint_init(ep, sk, gfp))
  		goto fail_init;
  
  	SCTP_DBG_OBJCNT_INC(ep);
  	return ep;
  
  fail_init:
  	kfree(ep);
  fail:
  	return NULL;
  }
  
  /* Add an association to an endpoint.  */
  void sctp_endpoint_add_asoc(struct sctp_endpoint *ep,
  			    struct sctp_association *asoc)
  {
  	struct sock *sk = ep->base.sk;
  
  	/* If this is a temporary association, don't bother
  	 * since we'll be removing it shortly and don't
  	 * want anyone to find it anyway.
  	 */
  	if (asoc->temp)
  		return;
  
  	/* Now just add it to our list of asocs */
  	list_add_tail(&asoc->asocs, &ep->asocs);
  
  	/* Increment the backlog value for a TCP-style listening socket. */
  	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
  		sk->sk_ack_backlog++;
  }
  
  /* Free the endpoint structure.  Delay cleanup until
   * all users have released their reference count on this structure.
   */
  void sctp_endpoint_free(struct sctp_endpoint *ep)
  {
  	ep->base.dead = true;
  
  	ep->base.sk->sk_state = SCTP_SS_CLOSED;
  
  	/* Unlink this endpoint, so we can't find it again! */
  	sctp_unhash_endpoint(ep);
  
  	sctp_endpoint_put(ep);
  }
  
  /* Final destructor for endpoint.  */
  static void sctp_endpoint_destroy(struct sctp_endpoint *ep)
  {
  	struct sock *sk;
  
  	if (unlikely(!ep->base.dead)) {
  		WARN(1, "Attempt to destroy undead endpoint %p!\n", ep);
  		return;
  	}
  
  	/* Free the digest buffer */
  	kfree(ep->digest);
  
  	/* SCTP-AUTH: Free up AUTH releated data such as shared keys
  	 * chunks and hmacs arrays that were allocated
  	 */
  	sctp_auth_destroy_keys(&ep->endpoint_shared_keys);
  	kfree(ep->auth_hmacs_list);
  	kfree(ep->auth_chunk_list);
  
  	/* AUTH - Free any allocated HMAC transform containers */
  	sctp_auth_destroy_hmacs(ep->auth_hmacs);
  
  	/* Cleanup. */
  	sctp_inq_free(&ep->base.inqueue);
  	sctp_bind_addr_free(&ep->base.bind_addr);
  
  	memset(ep->secret_key, 0, sizeof(ep->secret_key));
  
  	/* Give up our hold on the sock. */
  	sk = ep->base.sk;
  	if (sk != NULL) {
  		/* Remove and free the port */
  		if (sctp_sk(sk)->bind_hash)
  			sctp_put_port(sk);
  
  		sock_put(sk);
  	}
  
  	kfree(ep);
  	SCTP_DBG_OBJCNT_DEC(ep);
  }
  
  /* Hold a reference to an endpoint. */
  void sctp_endpoint_hold(struct sctp_endpoint *ep)
  {
  	atomic_inc(&ep->base.refcnt);
  }
  
  /* Release a reference to an endpoint and clean up if there are
   * no more references.
   */
  void sctp_endpoint_put(struct sctp_endpoint *ep)
  {
  	if (atomic_dec_and_test(&ep->base.refcnt))
  		sctp_endpoint_destroy(ep);
  }
  
  /* Is this the endpoint we are looking for?  */
  struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep,
  					       struct net *net,
  					       const union sctp_addr *laddr)
  {
  	struct sctp_endpoint *retval = NULL;
  
  	if ((htons(ep->base.bind_addr.port) == laddr->v4.sin_port) &&
  	    net_eq(sock_net(ep->base.sk), net)) {
  		if (sctp_bind_addr_match(&ep->base.bind_addr, laddr,
  					 sctp_sk(ep->base.sk)))
  			retval = ep;
  	}
  
  	return retval;
  }
  
  /* Find the association that goes with this chunk.
   * We do a linear search of the associations for this endpoint.
   * We return the matching transport address too.
   */
  static struct sctp_association *__sctp_endpoint_lookup_assoc(
  	const struct sctp_endpoint *ep,
  	const union sctp_addr *paddr,
  	struct sctp_transport **transport)
  {
  	struct sctp_association *asoc = NULL;
  	struct sctp_association *tmp;
  	struct sctp_transport *t = NULL;
  	struct sctp_hashbucket *head;
  	struct sctp_ep_common *epb;
  	int hash;
  	int rport;
  
  	*transport = NULL;
  
  	/* If the local port is not set, there can't be any associations
  	 * on this endpoint.
  	 */
  	if (!ep->base.bind_addr.port)
  		goto out;
  
  	rport = ntohs(paddr->v4.sin_port);
  
  	hash = sctp_assoc_hashfn(sock_net(ep->base.sk), ep->base.bind_addr.port,
  				 rport);
  	head = &sctp_assoc_hashtable[hash];
  	read_lock(&head->lock);
  	sctp_for_each_hentry(epb, &head->chain) {
  		tmp = sctp_assoc(epb);
  		if (tmp->ep != ep || rport != tmp->peer.port)
  			continue;
  
  		t = sctp_assoc_lookup_paddr(tmp, paddr);
  		if (t) {
  			asoc = tmp;
  			*transport = t;
  			break;
  		}
  	}
  	read_unlock(&head->lock);
  out:
  	return asoc;
  }
  
  /* Lookup association on an endpoint based on a peer address.  BH-safe.  */
  struct sctp_association *sctp_endpoint_lookup_assoc(
  	const struct sctp_endpoint *ep,
  	const union sctp_addr *paddr,
  	struct sctp_transport **transport)
  {
  	struct sctp_association *asoc;
  
  	local_bh_disable();
  	asoc = __sctp_endpoint_lookup_assoc(ep, paddr, transport);
  	local_bh_enable();
  
  	return asoc;
  }
  
  /* Look for any peeled off association from the endpoint that matches the
   * given peer address.
   */
  int sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,
  				const union sctp_addr *paddr)
  {
  	struct sctp_sockaddr_entry *addr;
  	struct sctp_bind_addr *bp;
  	struct net *net = sock_net(ep->base.sk);
  
  	bp = &ep->base.bind_addr;
  	/* This function is called with the socket lock held,
  	 * so the address_list can not change.
  	 */
  	list_for_each_entry(addr, &bp->address_list, list) {
  		if (sctp_has_association(net, &addr->a, paddr))
  			return 1;
  	}
  
  	return 0;
  }
  
  /* Do delayed input processing.  This is scheduled by sctp_rcv().
   * This may be called on BH or task time.
   */
  static void sctp_endpoint_bh_rcv(struct work_struct *work)
  {
  	struct sctp_endpoint *ep =
  		container_of(work, struct sctp_endpoint,
  			     base.inqueue.immediate);
  	struct sctp_association *asoc;
  	struct sock *sk;
  	struct net *net;
  	struct sctp_transport *transport;
  	struct sctp_chunk *chunk;
  	struct sctp_inq *inqueue;
  	sctp_subtype_t subtype;
  	sctp_state_t state;
  	int error = 0;
  	int first_time = 1;	/* is this the first time through the loop */
  
  	if (ep->base.dead)
  		return;
  
  	asoc = NULL;
  	inqueue = &ep->base.inqueue;
  	sk = ep->base.sk;
  	net = sock_net(sk);
  
  	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
  		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
  
  		/* If the first chunk in the packet is AUTH, do special
  		 * processing specified in Section 6.3 of SCTP-AUTH spec
  		 */
  		if (first_time && (subtype.chunk == SCTP_CID_AUTH)) {
  			struct sctp_chunkhdr *next_hdr;
  
  			next_hdr = sctp_inq_peek(inqueue);
  			if (!next_hdr)
  				goto normal;
  
  			/* If the next chunk is COOKIE-ECHO, skip the AUTH
  			 * chunk while saving a pointer to it so we can do
  			 * Authentication later (during cookie-echo
  			 * processing).
  			 */
  			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
  				chunk->auth_chunk = skb_clone(chunk->skb,
  								GFP_ATOMIC);
  				chunk->auth = 1;
  				continue;
  			}
  		}
  normal:
  		/* We might have grown an association since last we
  		 * looked, so try again.
  		 *
  		 * This happens when we've just processed our
  		 * COOKIE-ECHO chunk.
  		 */
  		if (NULL == chunk->asoc) {
  			asoc = sctp_endpoint_lookup_assoc(ep,
  							  sctp_source(chunk),
  							  &transport);
  			chunk->asoc = asoc;
  			chunk->transport = transport;
  		}
  
  		state = asoc ? asoc->state : SCTP_STATE_CLOSED;
  		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 (asoc && sctp_chunk_is_data(chunk))
  			asoc->peer.last_data_from = chunk->transport;
  		else {
  			SCTP_INC_STATS(sock_net(ep->base.sk), SCTP_MIB_INCTRLCHUNKS);
  			if (asoc)
  				asoc->stats.ictrlchunks++;
  		}
  
  		if (chunk->transport)
  			chunk->transport->last_time_heard = ktime_get();
  
  		error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype, state,
  				   ep, asoc, chunk, GFP_ATOMIC);
  
  		if (error && chunk)
  			chunk->pdiscard = 1;
  
  		/* Check to see if the endpoint is freed in response to
  		 * the incoming chunk. If so, get out of the while loop.
  		 */
  		if (!sctp_sk(sk)->ep)
  			break;
  
  		if (first_time)
  			first_time = 0;
  	}
  }
  