RE: [PATCH net] sctp: return a one-to-one type socket when doing peeloff
From: Leppanen, Jere (Nokia - FI/Espoo) <hidden>
Date: 2020-03-03 18:38:42
Also in:
linux-sctp
On Mon, 2 Mar 2020, Xin Long wrote:
As it says in rfc6458#section-9.2: The application uses the sctp_peeloff() call to branch off an association into a separate socket. (Note that the semantics are somewhat changed from the traditional one-to-one style accept() call.) Note also that the new socket is a one-to-one style socket. Thus, it will be confined to operations allowed for a one-to-one style socket. Prior to this patch, sctp_peeloff() returned a one-to-many type socket, on which some operations are not allowed, like shutdown, as Jere reported. This patch is to change it to return a one-to-one type socket instead.
Thanks for looking into this. I like the patch, and it fixes my simple
test case.
But with this patch, peeled-off sockets are created by copying from a
one-to-many socket to a one-to-one socket. Are you sure that that's
not going to cause any problems? Is it possible that there was a
reason why peeloff wasn't implemented this way in the first place?
With this patch there's no way to create UDP_HIGH_BANDWIDTH style
sockets anymore, so the remaining references should probably be
cleaned up:
./net/sctp/socket.c:1886: if (!sctp_style(sk, UDP_HIGH_BANDWIDTH) && msg->msg_name) {
./net/sctp/socket.c:8522: if (sctp_style(sk, UDP_HIGH_BANDWIDTH))
./include/net/sctp/structs.h:144: SCTP_SOCKET_UDP_HIGH_BANDWIDTH,
This patch disables those checks. The first one ignores a destination
address given to sendmsg() with a peeled-off socket - I don't know
why. The second one prevents listen() on a peeled-off socket.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Leppanen, Jere (Nokia - FI/Espoo) <redacted>Reported-by: Jere Leppanen <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Xin Long <lucien.xin@gmail.com> --- net/sctp/socket.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 1b56fc4..2b55beb 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c@@ -88,8 +88,7 @@ static int sctp_send_asconf(struct sctp_association *asoc, static int sctp_do_bind(struct sock *, union sctp_addr *, int); static int sctp_autobind(struct sock *sk); static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, - struct sctp_association *assoc, - enum sctp_socket_type type); + struct sctp_association *assoc); static unsigned long sctp_memory_pressure; static atomic_long_t sctp_memory_allocated;@@ -4965,7 +4964,7 @@ static struct sock *sctp_accept(struct sock *sk, int flags, int *err, bool kern) /* Populate the fields of the newsk from the oldsk and migrate the * asoc to the newsk. */ - error = sctp_sock_migrate(sk, newsk, asoc, SCTP_SOCKET_TCP); + error = sctp_sock_migrate(sk, newsk, asoc); if (error) { sk_common_release(newsk); newsk = NULL;@@ -5711,7 +5710,7 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) return -EINVAL; /* Create a new socket. */ - err = sock_create(sk->sk_family, SOCK_SEQPACKET, IPPROTO_SCTP, &sock); + err = sock_create(sk->sk_family, SOCK_STREAM, IPPROTO_SCTP, &sock); if (err < 0) return err;@@ -5727,8 +5726,7 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) /* Populate the fields of the newsk from the oldsk and migrate the * asoc to the newsk. */ - err = sctp_sock_migrate(sk, sock->sk, asoc, - SCTP_SOCKET_UDP_HIGH_BANDWIDTH); + err = sctp_sock_migrate(sk, sock->sk, asoc); if (err) { sock_release(sock); sock = NULL;@@ -9453,8 +9451,7 @@ static inline void sctp_copy_descendant(struct sock *sk_to, * and its messages to the newsk. */ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, - struct sctp_association *assoc, - enum sctp_socket_type type) + struct sctp_association *assoc) { struct sctp_sock *oldsp = sctp_sk(oldsk); struct sctp_sock *newsp = sctp_sk(newsk);@@ -9562,7 +9559,7 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, * original UDP-style socket or created with the accept() call on a * TCP-style socket.. */ - newsp->type = type; + newsp->type = SCTP_SOCKET_TCP; /* Mark the new socket "in-use" by the user so that any packets * that may arrive on the association after we've moved it are-- 2.1.0