From: David Howells Date: Wed, 5 Apr 2017 16:40:31 +0000 (+0100) Subject: Lock down TIOCSSERIAL X-Git-Tag: archive/raspbian/4.15.4-1+rpi1~38 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=5ca7fe4fa6f578ad47d98a6c873962d2a2a97b13;p=linux.git Lock down TIOCSSERIAL 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 Signed-off-by: David Howells Gbp-Pq: Topic features/all/lockdown Gbp-Pq: Name 0060-Lock-down-TIOCSSERIAL.patch --- diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 3a14cccbd7f..86edfb49043 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -842,6 +842,12 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, new_flags = (__force upf_t)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 ||