Re: [PATCH v2 2/2] libiscsi: disallow binding an already-bound connection

[Mike Christie]

On 5/23/24 5:21 PM, Khazhismel Kumykov wrote:
> This fixes issue where misbehaving userspace initiator could bind the
> same connection multiple times, which would leak the old connection
> socket without cleaning it up.
>
> For iscsi_tcp, it calls iscsi_suspend_tx directly in stop_conn. Update
> this to iscsi_conn_unbind, which matches the lifecycle of other drivers,
> and clears the CONN_FLAG_BOUND.
>
> Suggested-by: Mike Christie <michael....@oracle.com>
> Signed-off-by: Khazhismel Kumykov <kha...@google.com>
> ---
> drivers/scsi/iscsi_tcp.c | 2 +-
> drivers/scsi/libiscsi.c | 6 ++++++
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
> index deb9252e02e6..1d93404515ae 100644
> --- a/drivers/scsi/iscsi_tcp.c
> +++ b/drivers/scsi/iscsi_tcp.c
> @@ -696,7 +696,7 @@ static void iscsi_sw_tcp_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
> wake_up_interruptible(sk_sleep(sock->sk));
>
> /* stop xmit side */
> - iscsi_suspend_tx(conn);
> + iscsi_conn_unbind(cls_conn, true);
>
> /* stop recv side and release socket */
> iscsi_sw_tcp_release_conn(conn);
> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> index 0fda8905eabd..0fb98eb53584 100644
> --- a/drivers/scsi/libiscsi.c
> +++ b/drivers/scsi/libiscsi.c
> @@ -3453,6 +3453,12 @@ int iscsi_conn_bind(struct iscsi_cls_session *cls_session,
> struct iscsi_conn *conn = cls_conn->dd_data;
>
> spin_lock_bh(&session->frwd_lock);
> + if (test_bit(ISCSI_CONN_FLAG_BOUND, &conn->flags)) {
> + spin_unlock_bh(&session->frwd_lock);
> + return -EBUSY;
> + }
> +

If some of the driver's bind_conn callout fails then it could leave the
ISCSI_CONN_FLAG_BOUND bit set, and this will fail on a retry.

It's ok to call iscsi_conn_bind at the end of the bind_conn callout
like how iscsi_tcp and cxgbi* do. So for iscsi_iser.c, be_iscsi.c,
bnx2i_iscsi.c, and qedi_iscsi.c you need to move their iscsi_conn_bind
to the end of their bind_conn callout.

You could also keep the the existing flow but add unwind/goto error
handling to those drivers, but I think just moving the iscsi_conn_bind
call to the end of the function is easier and it syncs all the drivers
behavior which is nice.