linux-kernel - Re: [PATCH 34/39] Annotate hardware config module parameters in drivers/watchdog/

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Date:   Thu, 1 Dec 2016 04:58:54 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     David Howells <dhowells@...hat.com>, linux-kernel@...r.kernel.org
Cc:     gnomes@...rguk.ukuu.org.uk, linux-watchdog@...r.kernel.org,
        minyard@....org, Zwane Mwaikambo <zwanem@...il.com>,
        linux-security-module@...r.kernel.org,
        Wim Van Sebroeck <wim@...ana.be>, keyrings@...r.kernel.org
Subject: Re: [PATCH 34/39] Annotate hardware config module parameters in
 drivers/watchdog/

On 12/01/2016 04:34 AM, 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/watchdog/.
>
> Suggested-by: One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: Wim Van Sebroeck <wim@...ana.be>
> cc: Zwane Mwaikambo <zwanem@...il.com>
> cc: linux-watchdog@...r.kernel.org

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>
>  drivers/watchdog/cpu5wdt.c     |    2 +-
>  drivers/watchdog/eurotechwdt.c |    4 ++--
>  drivers/watchdog/pc87413_wdt.c |    2 +-
>  drivers/watchdog/sc1200wdt.c   |    2 +-
>  drivers/watchdog/wdt.c         |    4 ++--
>  5 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/watchdog/cpu5wdt.c b/drivers/watchdog/cpu5wdt.c
> index 6d03e8e30f8b..6c3f78e45c26 100644
> --- a/drivers/watchdog/cpu5wdt.c
> +++ b/drivers/watchdog/cpu5wdt.c
> @@ -289,7 +289,7 @@ MODULE_DESCRIPTION("sma cpu5 watchdog driver");
>  MODULE_SUPPORTED_DEVICE("sma cpu5 watchdog");
>  MODULE_LICENSE("GPL");
>
> -module_param(port, int, 0);
> +module_param_hw(port, int, ioport, 0);
>  MODULE_PARM_DESC(port, "base address of watchdog card, default is 0x91");
>
>  module_param(verbose, int, 0);
> diff --git a/drivers/watchdog/eurotechwdt.c b/drivers/watchdog/eurotechwdt.c
> index 23ee53240c4c..38e96712264f 100644
> --- a/drivers/watchdog/eurotechwdt.c
> +++ b/drivers/watchdog/eurotechwdt.c
> @@ -97,9 +97,9 @@ MODULE_PARM_DESC(nowayout,
>  #define WDT_TIMER_CFG		0xf3
>
>
> -module_param(io, int, 0);
> +module_param_hw(io, int, ioport, 0);
>  MODULE_PARM_DESC(io, "Eurotech WDT io port (default=0x3f0)");
> -module_param(irq, int, 0);
> +module_param_hw(irq, int, irq, 0);
>  MODULE_PARM_DESC(irq, "Eurotech WDT irq (default=10)");
>  module_param(ev, charp, 0);
>  MODULE_PARM_DESC(ev, "Eurotech WDT event type (default is `int')");
> diff --git a/drivers/watchdog/pc87413_wdt.c b/drivers/watchdog/pc87413_wdt.c
> index 9f15dd9435d1..06a892e36a8d 100644
> --- a/drivers/watchdog/pc87413_wdt.c
> +++ b/drivers/watchdog/pc87413_wdt.c
> @@ -579,7 +579,7 @@ MODULE_AUTHOR("Marcus Junker <junker@...uras.de>");
>  MODULE_DESCRIPTION("PC87413 WDT driver");
>  MODULE_LICENSE("GPL");
>
> -module_param(io, int, 0);
> +module_param_hw(io, int, ioport, 0);
>  MODULE_PARM_DESC(io, MODNAME " I/O port (default: "
>  					__MODULE_STRING(IO_DEFAULT) ").");
>
> diff --git a/drivers/watchdog/sc1200wdt.c b/drivers/watchdog/sc1200wdt.c
> index 131193a7acdf..b34d3d5ba632 100644
> --- a/drivers/watchdog/sc1200wdt.c
> +++ b/drivers/watchdog/sc1200wdt.c
> @@ -88,7 +88,7 @@ MODULE_PARM_DESC(isapnp,
>  	"When set to 0 driver ISA PnP support will be disabled");
>  #endif
>
> -module_param(io, int, 0);
> +module_param_hw(io, int, ioport, 0);
>  MODULE_PARM_DESC(io, "io port");
>  module_param(timeout, int, 0);
>  MODULE_PARM_DESC(timeout, "range is 0-255 minutes, default is 1");
> diff --git a/drivers/watchdog/wdt.c b/drivers/watchdog/wdt.c
> index e0206b5b7d89..e481fbbc4ae7 100644
> --- a/drivers/watchdog/wdt.c
> +++ b/drivers/watchdog/wdt.c
> @@ -78,9 +78,9 @@ static int irq = 11;
>
>  static DEFINE_SPINLOCK(wdt_lock);
>
> -module_param(io, int, 0);
> +module_param_hw(io, int, ioport, 0);
>  MODULE_PARM_DESC(io, "WDT io port (default=0x240)");
> -module_param(irq, int, 0);
> +module_param_hw(irq, int, irq, 0);
>  MODULE_PARM_DESC(irq, "WDT irq (default=11)");
>
>  /* Support for the Fan Tachometer on the WDT501-P */
>
> --
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