staging: fwserial: fix TIOCSSERIAL implementation

BugLink: https://bugs.launchpad.net/bugs/1929455
[ Upstream commit a7eaaa9d1032e68669bb479496087ba8fc155ab6 ]

TIOCSSERIAL is a horrid, underspecified, legacy interface which for most
serial devices is only useful for setting the close_delay and
closing_wait parameters.

A non-privileged user has only ever been able to set the since long
deprecated ASYNC_SPD flags and trying to change any other *supported*
feature should result in -EPERM being returned. Setting the current
values for any supported features should return success.

Fix the fwserial implementation which was returning -EPERM also for a
privileged user when trying to change certain unsupported parameters,
and instead return success consistently.

Fixes: 7355ba3445f2 ("staging: fwserial: Add TTY-over-Firewire serial driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407102334.32361-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
index 440d11423812587922eb99ce63d8edac54add5c8..2888b80a2c1a96418c5900bceb4dffa55ff1075f 100644 (file)
--- a/drivers/staging/fwserial/fwserial.c
+++ b/drivers/staging/fwserial/fwserial.c
@@ -1234,10 +1234,6 @@ static int set_serial_info(struct tty_struct *tty,
        struct fwtty_port *port = tty->driver_data;
        unsigned int cdelay;
 
-       if (ss->irq != 0 || ss->port != 0 || ss->custom_divisor != 0 ||
-           ss->baud_base != 400000000)
-               return -EPERM;
-
        cdelay = msecs_to_jiffies(ss->close_delay * 10);
 
        mutex_lock(&port->port.mutex);