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 kind of confusing, it is identical
to SO_REUSEADDR with some extra restriction, so 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.
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
include/net/sctp/structs.h | 1 +
include/uapi/linux/sctp.h | 1 +
net/sctp/socket.c | 62 ++++++++++++++++++++++++++++++++++++++++------
3 files changed, 57 insertions(+), 7 deletions(-)
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index dbe1b91..5764a3d 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -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,
diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
index b64d583..c02986a 100644
--- a/include/uapi/linux/sctp.h
+++ b/include/uapi/linux/sctp.h
@@ -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.
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index d20f7ad..d71d224 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4169,6 +4169,28 @@ 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
@@ -4363,6 +4385,9 @@ 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;
@@ -7196,6 +7221,26 @@ 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)
{
@@ -7391,6 +7436,9 @@ 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;
@@ -7428,6 +7476,7 @@ 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;
@@ -7500,13 +7549,11 @@ 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
@@ -7524,7 +7571,7 @@ 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;
@@ -7548,12 +7595,12 @@ 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
@@ -7684,7 +7731,7 @@ 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;
}
@@ -8549,6 +8596,7 @@ 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;
--
2.1.0
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