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Commit b0e9a2fe authored by Xin Long's avatar Xin Long Committed by David S. Miller
Browse files

sctp: add support for SCTP_REUSE_PORT sockopt 



This feature is actually already supported by sk->sk_reuse which can be
set by socket level opt SO_REUSEADDR. But it's not working exactly as
RFC6458 demands in section 8.1.27, like:

  - This option only supports one-to-one style SCTP sockets
  - This socket option must not be used after calling bind()
    or sctp_bindx().

Besides, SCTP_REUSE_PORT sockopt should be provided for user's programs.
Otherwise, the programs with SCTP_REUSE_PORT from other systems will not
work in linux.

To separate it from the socket level version, this patch adds 'reuse' in
sctp_sock and it works pretty much as sk->sk_reuse, but with some extra
setup limitations that are needed when it is being enabled.

"It should be noted that the behavior of the socket-level socket option
to reuse ports and/or addresses for SCTP sockets is unspecified", so it
leaves SO_REUSEADDR as is for the compatibility.

Note that the name SCTP_REUSE_PORT is somewhat confusing, as its
functionality is nearly identical to SO_REUSEADDR, but with some
extra restrictions. Here it uses 'reuse' in sctp_sock instead of
'reuseport'. As for sk->sk_reuseport support for SCTP, it will be
added in another patch.

Thanks to Neil to make this clear.

v1->v2:
  - add sctp_sk->reuse to separate it from the socket level version.
v2->v3:
  - improve changelog according to Marcelo's suggestion.

Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 23c94d63

include/net/sctp/structs.h

+1 −0
Original line number Diff line number Diff line
@@ -220,6 +220,7 @@ struct sctp_sock { 
	__u32 adaptation_ind;

	__u32 pd_point;

	__u16	nodelay:1,

		reuse:1,

		disable_fragments:1,

		v4mapped:1,

		frag_interleave:1,

include/uapi/linux/sctp.h

+1 −0
Original line number Diff line number Diff line
@@ -100,6 +100,7 @@ typedef __s32 sctp_assoc_t; 
#define SCTP_RECVNXTINFO	33

#define SCTP_DEFAULT_SNDINFO	34

#define SCTP_AUTH_DEACTIVATE_KEY	35

#define SCTP_REUSE_PORT		36



/* Internal Socket Options. Some of the sctp library functions are

 * implemented using these socket options.

net/sctp/socket.c

+55 −7
Original line number Diff line number Diff line
@@ -4170,6 +4170,28 @@ static int sctp_setsockopt_interleaving_supported(struct sock *sk, 
	return retval;

}



static int sctp_setsockopt_reuse_port(struct sock *sk, char __user *optval,

				      unsigned int optlen)

{

	int val;



	if (!sctp_style(sk, TCP))

		return -EOPNOTSUPP;



	if (sctp_sk(sk)->ep->base.bind_addr.port)

		return -EFAULT;



	if (optlen < sizeof(int))

		return -EINVAL;



	if (get_user(val, (int __user *)optval))

		return -EFAULT;



	sctp_sk(sk)->reuse = !!val;



	return 0;

}



/* API 6.2 setsockopt(), getsockopt()

 *

 * Applications use setsockopt() and getsockopt() to set or retrieve
@@ -4364,6 +4386,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname, 
		retval = sctp_setsockopt_interleaving_supported(sk, optval,

								optlen);

		break;

	case SCTP_REUSE_PORT:

		retval = sctp_setsockopt_reuse_port(sk, optval, optlen);

		break;

	default:

		retval = -ENOPROTOOPT;

		break;
@@ -7197,6 +7222,26 @@ static int sctp_getsockopt_interleaving_supported(struct sock *sk, int len, 
	return retval;

}



static int sctp_getsockopt_reuse_port(struct sock *sk, int len,

				      char __user *optval,

				      int __user *optlen)

{

	int val;



	if (len < sizeof(int))

		return -EINVAL;



	len = sizeof(int);

	val = sctp_sk(sk)->reuse;

	if (put_user(len, optlen))

		return -EFAULT;



	if (copy_to_user(optval, &val, len))

		return -EFAULT;



	return 0;

}



static int sctp_getsockopt(struct sock *sk, int level, int optname,

			   char __user *optval, int __user *optlen)

{
@@ -7392,6 +7437,9 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname, 
		retval = sctp_getsockopt_interleaving_supported(sk, len, optval,

								optlen);

		break;

	case SCTP_REUSE_PORT:

		retval = sctp_getsockopt_reuse_port(sk, len, optval, optlen);

		break;

	default:

		retval = -ENOPROTOOPT;

		break;
@@ -7429,6 +7477,7 @@ static struct sctp_bind_bucket *sctp_bucket_create( 


static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)

{

	bool reuse = (sk->sk_reuse || sctp_sk(sk)->reuse);

	struct sctp_bind_hashbucket *head; /* hash list */

	struct sctp_bind_bucket *pp;

	unsigned short snum;
@@ -7501,13 +7550,11 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr) 
		 * used by other socket (pp->owner not empty); that other

		 * socket is going to be sk2.

		 */

		int reuse = sk->sk_reuse;

		struct sock *sk2;



		pr_debug("%s: found a possible match\n", __func__);



		if (pp->fastreuse && sk->sk_reuse &&

			sk->sk_state != SCTP_SS_LISTENING)

		if (pp->fastreuse && reuse && sk->sk_state != SCTP_SS_LISTENING)

			goto success;



		/* Run through the list of sockets bound to the port
@@ -7525,7 +7572,7 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr) 
			ep2 = sctp_sk(sk2)->ep;



			if (sk == sk2 ||

			    (reuse && sk2->sk_reuse &&

			    (reuse && (sk2->sk_reuse || sctp_sk(sk2)->reuse) &&

			     sk2->sk_state != SCTP_SS_LISTENING))

				continue;
@@ -7549,12 +7596,12 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr) 
	 * SO_REUSEADDR on this socket -sk-).

	 */

	if (hlist_empty(&pp->owner)) {

		if (sk->sk_reuse && sk->sk_state != SCTP_SS_LISTENING)

		if (reuse && sk->sk_state != SCTP_SS_LISTENING)

			pp->fastreuse = 1;

		else

			pp->fastreuse = 0;

	} else if (pp->fastreuse &&

		(!sk->sk_reuse || sk->sk_state == SCTP_SS_LISTENING))

		   (!reuse || sk->sk_state == SCTP_SS_LISTENING))

		pp->fastreuse = 0;



	/* We are set, so fill up all the data in the hash table
@@ -7685,7 +7732,7 @@ int sctp_inet_listen(struct socket *sock, int backlog) 
		err = 0;

		sctp_unhash_endpoint(ep);

		sk->sk_state = SCTP_SS_CLOSED;

		if (sk->sk_reuse)

		if (sk->sk_reuse || sctp_sk(sk)->reuse)

			sctp_sk(sk)->bind_hash->fastreuse = 1;

		goto out;

	}
@@ -8550,6 +8597,7 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk, 
	newsk->sk_no_check_tx = sk->sk_no_check_tx;

	newsk->sk_no_check_rx = sk->sk_no_check_rx;

	newsk->sk_reuse = sk->sk_reuse;

	sctp_sk(newsk)->reuse = sp->reuse;



	newsk->sk_shutdown = sk->sk_shutdown;

	newsk->sk_destruct = sctp_destruct_sock;