Commit 45122ca2 authored by Thomas Graf's avatar Thomas Graf Committed by David S. Miller
Browse files

sctp: Add RCU protection to assoc->transport_addr_list 



peer.transport_addr_list is currently only protected by sk_sock
which is inpractical to acquire for procfs dumping purposes.

This patch adds RCU protection allowing for the procfs readers to
enter RCU read-side critical sections.

Modification of the list continues to be serialized via sk_lock.

V2: Use list_del_rcu() in sctp_association_free() to be safe
    Skip transports marked dead when dumping for procfs

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarThomas Graf <tgraf@suug.ch>
Acked-by: default avatarVlad Yasevich <vyasevich@gmail.com>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0b0fe913

include/net/sctp/structs.h

+2 −0
Original line number Diff line number Diff line
@@ -949,6 +949,8 @@ struct sctp_transport { 


	/* 64-bit random number sent with heartbeat. */

	__u64 hb_nonce;



	struct rcu_head rcu;

};



struct sctp_transport *sctp_transport_new(struct net *, const union sctp_addr *,

net/sctp/associola.c

+3 −3
Original line number Diff line number Diff line
@@ -448,7 +448,7 @@ void sctp_association_free(struct sctp_association *asoc) 
	/* 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(pos);

		list_del_rcu(pos);

		sctp_transport_free(transport);

	}
@@ -568,7 +568,7 @@ void sctp_assoc_rm_peer(struct sctp_association *asoc, 
		sctp_assoc_update_retran_path(asoc);



	/* Remove this peer from the list. */

	list_del(&peer->transports);

	list_del_rcu(&peer->transports);



	/* Get the first transport of asoc. */

	pos = asoc->peer.transport_addr_list.next;
@@ -769,7 +769,7 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc, 
	peer->state = peer_state;



	/* Attach the remote transport to our asoc.  */

	list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);

	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.  */

net/sctp/proc.c

+12 −2
Original line number Diff line number Diff line
@@ -162,15 +162,20 @@ static void sctp_seq_dump_remote_addrs(struct seq_file *seq, struct sctp_associa 
	struct sctp_af *af;



	primary = &assoc->peer.primary_addr;

	list_for_each_entry(transport, &assoc->peer.transport_addr_list,

	rcu_read_lock();

	list_for_each_entry_rcu(transport, &assoc->peer.transport_addr_list,

			transports) {

		addr = &transport->ipaddr;

		if (transport->dead)

			continue;



		af = sctp_get_af_specific(addr->sa.sa_family);

		if (af->cmp_addr(addr, primary)) {

			seq_printf(seq, "*");

		}

		af->seq_dump_addr(seq, addr);

	}

	rcu_read_unlock();

}



static void * sctp_eps_seq_start(struct seq_file *seq, loff_t *pos)
@@ -441,12 +446,16 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, void *v) 
	head = &sctp_assoc_hashtable[hash];

	sctp_local_bh_disable();

	read_lock(&head->lock);

	rcu_read_lock();

	sctp_for_each_hentry(epb, node, &head->chain) {

		if (!net_eq(sock_net(epb->sk), seq_file_net(seq)))

			continue;

		assoc = sctp_assoc(epb);

		list_for_each_entry(tsp, &assoc->peer.transport_addr_list,

		list_for_each_entry_rcu(tsp, &assoc->peer.transport_addr_list,

					transports) {

			if (tsp->dead)

				continue;



			/*

			 * The remote address (ADDR)

			 */
@@ -492,6 +501,7 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, void *v) 
		}

	}



	rcu_read_unlock();

	read_unlock(&head->lock);

	sctp_local_bh_enable();

net/sctp/transport.c

+13 −5
Original line number Diff line number Diff line
@@ -163,13 +163,11 @@ void sctp_transport_free(struct sctp_transport *transport) 
	sctp_transport_put(transport);

}



/* Destroy the transport data structure.

 * Assumes there are no more users of this structure.

 */

static void sctp_transport_destroy(struct sctp_transport *transport)

static void sctp_transport_destroy_rcu(struct rcu_head *head)

{

	SCTP_ASSERT(transport->dead, "Transport is not dead", return);

	struct sctp_transport *transport;



	transport = container_of(head, struct sctp_transport, rcu);

	if (transport->asoc)

		sctp_association_put(transport->asoc);
@@ -180,6 +178,16 @@ static void sctp_transport_destroy(struct sctp_transport *transport) 
	SCTP_DBG_OBJCNT_DEC(transport);

}



/* Destroy the transport data structure.

 * Assumes there are no more users of this structure.

 */

static void sctp_transport_destroy(struct sctp_transport *transport)

{

	SCTP_ASSERT(transport->dead, "Transport is not dead", return);



	call_rcu(&transport->rcu, sctp_transport_destroy_rcu);

}



/* Start T3_rtx timer if it is not already running and update the heartbeat

 * timer.  This routine is called every time a DATA chunk is sent.

 */

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