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: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2018-06-28 15:31:00 +08:00 committed by David S. Miller
parent 23c94d63a7
commit b0e9a2fe3f
3 changed files with 57 additions and 7 deletions

View File

@ -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,

View File

@ -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.

View File

@ -4170,6 +4170,28 @@ out:
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 @@ out:
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 @@ pp_found:
* 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 @@ pp_found:
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 @@ pp_not_found:
* 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;