| Subject | [PATCH 23/24] Lock down TIOCSSERIAL | From | David Howells <> | Date | Wed, 05 Apr 2017 21:17:55 +0100 |
| |
Lock down TIOCSSERIAL as that can be used to change the ioport and irq settings on a serial port. This only appears to be an issue for the serial drivers that use the core serial code. All other drivers seem to either ignore attempts to change port/irq or give an error.
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: David Howells <dhowells@redhat.com> cc: Jiri Slaby <jslaby@suse.com> ---
drivers/tty/serial/serial_core.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 3fe56894974a..4181b0004de9 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -821,6 +821,12 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, new_flags = new_info->flags; old_custom_divisor = uport->custom_divisor; + if ((change_port || change_irq) && kernel_is_locked_down()) { + pr_err("Using TIOCSSERIAL to change device addresses, irqs and dma channels is not permitted when the kernel is locked down\n"); + retval = -EPERM; + goto exit; + } + if (!capable(CAP_SYS_ADMIN)) { retval = -EPERM; if (change_irq || change_port ||
|