[PATCH 32/38] Annotate hardware config module parameters in drivers/video/

[PATCH 32/38] Annotate hardware config module parameters in drivers/video/

[David Howells]

When the kernel is running in secure boot mode, we lock down the kernel to
prevent userspace from modifying the running kernel image.  Whilst this
includes prohibiting access to things like /dev/mem, it must also prevent
access by means of configuring driver modules in such a way as to cause a
device to access or modify the kernel image.

To this end, annotate module_param* statements that refer to hardware
configuration and indicate for future reference what type of parameter they
specify.  The parameter parser in the core sees this information and can
skip such parameters with an error message if the kernel is locked down.
The module initialisation then runs as normal, but just sees whatever the
default values for those parameters is.

Note that we do still need to do the module initialisation because some
drivers have viable defaults set in case parameters aren't specified and
some drivers support automatic configuration (e.g. PNP or PCI) in addition
to manually coded parameters.

This patch annotates drivers in drivers/video/.

Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jaya Kumar <jayalk@intworks.biz>
cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
cc: linux-fbdev@vger.kernel.org
---

 drivers/video/fbdev/arcfb.c |    8 ++++----
 drivers/video/fbdev/n411.c  |    6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/video/fbdev/arcfb.c b/drivers/video/fbdev/arcfb.c
index 1928cb2b5386..7e87d0d61658 100644
--- a/drivers/video/fbdev/arcfb.c
+++ b/drivers/video/fbdev/arcfb.c
@@ -645,17 +645,17 @@ module_param(nosplash, uint, 0);
 MODULE_PARM_DESC(nosplash, "Disable doing the splash screen");
 module_param(arcfb_enable, uint, 0);
 MODULE_PARM_DESC(arcfb_enable, "Enable communication with Arc board");
-module_param(dio_addr, ulong, 0);
+module_param_hw(dio_addr, ulong, ioport, 0);
 MODULE_PARM_DESC(dio_addr, "IO address for data, eg: 0x480");
-module_param(cio_addr, ulong, 0);
+module_param_hw(cio_addr, ulong, ioport, 0);
 MODULE_PARM_DESC(cio_addr, "IO address for control, eg: 0x400");
-module_param(c2io_addr, ulong, 0);
+module_param_hw(c2io_addr, ulong, ioport, 0);
 MODULE_PARM_DESC(c2io_addr, "IO address for secondary control, eg: 0x408");
 module_param(splashval, ulong, 0);
 MODULE_PARM_DESC(splashval, "Splash pattern: 0xFF is black, 0x00 is green");
 module_param(tuhold, ulong, 0);
 MODULE_PARM_DESC(tuhold, "Time to hold between strobing data to Arc board");
-module_param(irq, uint, 0);
+module_param_hw(irq, uint, irq, 0);
 MODULE_PARM_DESC(irq, "IRQ for the Arc board");
 
 module_init(arcfb_init);
diff --git a/drivers/video/fbdev/n411.c b/drivers/video/fbdev/n411.c
index 053deacad7cc..a3677313396e 100644
--- a/drivers/video/fbdev/n411.c
+++ b/drivers/video/fbdev/n411.c
@@ -193,11 +193,11 @@ module_exit(n411_exit);
 
 module_param(nosplash, uint, 0);
 MODULE_PARM_DESC(nosplash, "Disable doing the splash screen");
-module_param(dio_addr, ulong, 0);
+module_param_hw(dio_addr, ulong, ioport, 0);
 MODULE_PARM_DESC(dio_addr, "IO address for data, eg: 0x480");
-module_param(cio_addr, ulong, 0);
+module_param_hw(cio_addr, ulong, ioport, 0);
 MODULE_PARM_DESC(cio_addr, "IO address for control, eg: 0x400");
-module_param(c2io_addr, ulong, 0);
+module_param_hw(c2io_addr, ulong, ioport, 0);
 MODULE_PARM_DESC(c2io_addr, "IO address for secondary control, eg: 0x408");
 module_param(splashval, ulong, 0);
 MODULE_PARM_DESC(splashval, "Splash pattern: 0x00 is black, 0x01 is white");

Re: [PATCH 32/38] Annotate hardware config module parameters in drivers/video/

[Bartlomiej Zolnierkiewicz]

On Wednesday, April 05, 2017 06:01:34 PM David Howells wrote:
> When the kernel is running in secure boot mode, we lock down the kernel to
> prevent userspace from modifying the running kernel image.  Whilst this
> includes prohibiting access to things like /dev/mem, it must also prevent
> access by means of configuring driver modules in such a way as to cause a
> device to access or modify the kernel image.
> 
> To this end, annotate module_param* statements that refer to hardware
> configuration and indicate for future reference what type of parameter they
> specify.  The parameter parser in the core sees this information and can
> skip such parameters with an error message if the kernel is locked down.
> The module initialisation then runs as normal, but just sees whatever the
> default values for those parameters is.
> 
> Note that we do still need to do the module initialisation because some
> drivers have viable defaults set in case parameters aren't specified and
> some drivers support automatic configuration (e.g. PNP or PCI) in addition
> to manually coded parameters.
> 
> This patch annotates drivers in drivers/video/.
> 
> Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Jaya Kumar <jayalk@intworks.biz>
> cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> cc: linux-fbdev@vger.kernel.org

Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics