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Date: Thu, 9 Nov 2017 17:33:17 +0000 From: David Howells <dhowells@...hat.com> To: linux-security-module@...r.kernel.org Cc: gnomes@...rguk.ukuu.org.uk, linux-efi@...r.kernel.org, dhowells@...hat.com, linux-kernel@...r.kernel.org, jforbes@...hat.com Subject: [PATCH 21/30] 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 <gregkh@...uxfoundation.org> Signed-off-by: David Howells <dhowells@...hat.com> cc: Jiri Slaby <jslaby@...e.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 3a14cccbd7ff..41f0922ad842 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("Using TIOCSSERIAL to change device addresses, irqs and dma channels")) { + retval = -EPERM; + goto exit; + } + if (!capable(CAP_SYS_ADMIN)) { retval = -EPERM; if (change_irq || change_port ||
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