[PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

[PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

[Fernando Eckhardt Valle]

Newer Thinkpads have a feature called MAC Address Pass-through.
This patch provides a sysfs interface that userspace can use
to get this auxiliary mac address.

Signed-off-by: Fernando Eckhardt Valle <fevalle@ipt.br>
---
Changes in v4:
- strscpy() in all string copies.
Changes in v3:
- Added null terminator to auxmac string when copying auxiliary
mac address value.
Changes in v2:
- Added documentation.
- All handling of the auxmac value is done in the _init function.
---
 .../admin-guide/laptops/thinkpad-acpi.rst     | 20 +++++
 drivers/platform/x86/thinkpad_acpi.c          | 79 +++++++++++++++++++
 2 files changed, 99 insertions(+)

diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
index e27a1c3f6..98d304010 100644
--- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
+++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
@@ -53,6 +53,7 @@ detailed description):
 	- Lap mode sensor
 	- Setting keyboard language
 	- WWAN Antenna type
+	- Auxmac
 
 A compatibility table by model and feature is maintained on the web
 site, http://ibm-acpi.sf.net/. I appreciate any success or failure
@@ -1511,6 +1512,25 @@ Currently 2 antenna types are supported as mentioned below:
 The property is read-only. If the platform doesn't have support the sysfs
 class is not created.
 
+Auxmac
+------
+
+sysfs: auxmac
+
+Some newer Thinkpads have a feature called MAC Address Pass-through. This
+feature is implemented by the system firmware to provide a system unique MAC,
+that can override a dock or USB ethernet dongle MAC, when connected to a
+network. This property enables user-space to easily determine the MAC address
+if the feature is enabled.
+
+The values of this auxiliary MAC are:
+
+        cat /sys/devices/platform/thinkpad_acpi/auxmac
+
+If the feature is disabled, the value will be 'disabled'.
+
+This property is read-only.
+
 Adaptive keyboard
 -----------------
 
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index d70c89d32..f430cc9ed 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -10785,6 +10785,80 @@ static struct ibm_struct dprc_driver_data = {
 	.name = "dprc",
 };
 
+/*
+ * Auxmac
+ *
+ * This auxiliary mac address is enabled in the bios through the
+ * MAC Address Pass-through feature. In most cases, there are three
+ * possibilities: Internal Mac, Second Mac, and disabled.
+ *
+ */
+
+#define AUXMAC_LEN 12
+#define AUXMAC_START 9
+#define AUXMAC_STRLEN 22
+#define AUXMAC_BEGIN_MARKER 8
+#define AUXMAC_END_MARKER 21
+
+static char auxmac[AUXMAC_LEN + 1];
+
+static int auxmac_init(struct ibm_init_struct *iibm)
+{
+	acpi_status status;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+
+	status = acpi_evaluate_object(NULL, "\\MACA", NULL, &buffer);
+
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	obj = buffer.pointer;
+
+	if (obj->type != ACPI_TYPE_STRING || obj->string.length != AUXMAC_STRLEN) {
+		pr_info("Invalid buffer for MAC address pass-through.\n");
+		strscpy(auxmac, "unavailable", AUXMAC_LEN);
+		goto auxmacinvalid;
+	}
+
+	if (obj->string.pointer[AUXMAC_BEGIN_MARKER] != '#' ||
+	    obj->string.pointer[AUXMAC_END_MARKER] != '#') {
+		pr_info("Invalid header for MAC address pass-through.\n");
+		strscpy(auxmac, "unavailable", AUXMAC_LEN);
+		goto auxmacinvalid;
+	}
+
+	if (strncmp(obj->string.pointer + AUXMAC_START, "XXXXXXXXXXXX", AUXMAC_LEN) != 0)
+		strscpy(auxmac, obj->string.pointer + AUXMAC_START, AUXMAC_LEN + 1);
+	else
+		strscpy(auxmac, "disabled", AUXMAC_START);
+
+auxmacinvalid:
+	kfree(obj);
+	return 0;
+}
+
+static struct ibm_struct auxmac_data = {
+	.name = "auxmac",
+};
+
+static ssize_t auxmac_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	return sysfs_emit(buf, "%s\n", auxmac);
+}
+static DEVICE_ATTR_RO(auxmac);
+
+static struct attribute *auxmac_attributes[] = {
+	&dev_attr_auxmac.attr,
+	NULL
+};
+
+static const struct attribute_group auxmac_attr_group = {
+	.attrs = auxmac_attributes,
+};
+
 /* --------------------------------------------------------------------- */
 
 static struct attribute *tpacpi_driver_attributes[] = {
@@ -10843,6 +10917,7 @@ static const struct attribute_group *tpacpi_groups[] = {
 	&proxsensor_attr_group,
 	&kbdlang_attr_group,
 	&dprc_attr_group,
+	&auxmac_attr_group,
 	NULL,
 };
 
@@ -11414,6 +11489,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
 		.init = tpacpi_dprc_init,
 		.data = &dprc_driver_data,
 	},
+	{
+		.init = auxmac_init,
+		.data = &auxmac_data,
+	},
 };
 
 static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
-- 
2.25.1

Re: [PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

[Ilpo Järvinen]

On Thu, 21 Sep 2023, Fernando Eckhardt Valle wrote:

> Newer Thinkpads have a feature called MAC Address Pass-through.
> This patch provides a sysfs interface that userspace can use
> to get this auxiliary mac address.
> 
> Signed-off-by: Fernando Eckhardt Valle <fevalle@ipt.br>
> ---
> Changes in v4:
> - strscpy() in all string copies.
> Changes in v3:
> - Added null terminator to auxmac string when copying auxiliary
> mac address value.
> Changes in v2:
> - Added documentation.
> - All handling of the auxmac value is done in the _init function.
> ---
>  .../admin-guide/laptops/thinkpad-acpi.rst     | 20 +++++
>  drivers/platform/x86/thinkpad_acpi.c          | 79 +++++++++++++++++++
>  2 files changed, 99 insertions(+)
> 
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index e27a1c3f6..98d304010 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -53,6 +53,7 @@ detailed description):
>  	- Lap mode sensor
>  	- Setting keyboard language
>  	- WWAN Antenna type
> +	- Auxmac
>  
>  A compatibility table by model and feature is maintained on the web
>  site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1511,6 +1512,25 @@ Currently 2 antenna types are supported as mentioned below:
>  The property is read-only. If the platform doesn't have support the sysfs
>  class is not created.
>  
> +Auxmac
> +------
> +
> +sysfs: auxmac
> +
> +Some newer Thinkpads have a feature called MAC Address Pass-through. This
> +feature is implemented by the system firmware to provide a system unique MAC,
> +that can override a dock or USB ethernet dongle MAC, when connected to a
> +network. This property enables user-space to easily determine the MAC address
> +if the feature is enabled.
> +
> +The values of this auxiliary MAC are:
> +
> +        cat /sys/devices/platform/thinkpad_acpi/auxmac
> +
> +If the feature is disabled, the value will be 'disabled'.
> +
> +This property is read-only.
> +
>  Adaptive keyboard
>  -----------------
>  
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index d70c89d32..f430cc9ed 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -10785,6 +10785,80 @@ static struct ibm_struct dprc_driver_data = {
>  	.name = "dprc",
>  };
>  
> +/*
> + * Auxmac
> + *
> + * This auxiliary mac address is enabled in the bios through the
> + * MAC Address Pass-through feature. In most cases, there are three
> + * possibilities: Internal Mac, Second Mac, and disabled.
> + *
> + */
> +
> +#define AUXMAC_LEN 12
> +#define AUXMAC_START 9
> +#define AUXMAC_STRLEN 22
> +#define AUXMAC_BEGIN_MARKER 8
> +#define AUXMAC_END_MARKER 21
> +
> +static char auxmac[AUXMAC_LEN + 1];
> +
> +static int auxmac_init(struct ibm_init_struct *iibm)
> +{
> +	acpi_status status;
> +	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *obj;
> +
> +	status = acpi_evaluate_object(NULL, "\\MACA", NULL, &buffer);
> +
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	obj = buffer.pointer;
> +
> +	if (obj->type != ACPI_TYPE_STRING || obj->string.length != AUXMAC_STRLEN) {
> +		pr_info("Invalid buffer for MAC address pass-through.\n");
> +		strscpy(auxmac, "unavailable", AUXMAC_LEN);
> +		goto auxmacinvalid;
> +	}
> +
> +	if (obj->string.pointer[AUXMAC_BEGIN_MARKER] != '#' ||
> +	    obj->string.pointer[AUXMAC_END_MARKER] != '#') {
> +		pr_info("Invalid header for MAC address pass-through.\n");
> +		strscpy(auxmac, "unavailable", AUXMAC_LEN);
> +		goto auxmacinvalid;
> +	}
> +
> +	if (strncmp(obj->string.pointer + AUXMAC_START, "XXXXXXXXXXXX", AUXMAC_LEN) != 0)
> +		strscpy(auxmac, obj->string.pointer + AUXMAC_START, AUXMAC_LEN + 1);

Okay, I wasn't expecting this change as this relies on the nul termination 
by strscpy() since the original buffer does not have one but the # 
character there. But I guess it isn't harmful either.

> +	else
> +		strscpy(auxmac, "disabled", AUXMAC_START);

AUXMAC_START is an offset ??? It should be AUXMAC_LEN.

> +
> +auxmacinvalid:
> +	kfree(obj);
> +	return 0;

I only now realized there are two gotos to auxmacinvalid. Therefore, I'd 
do this instead:

free:
	kfree(obj);
	return 0;
auxmacinvalid:
	strscpy(auxmac, "unavailable", AUXMAC_LEN);
	goto free;

I'm sorry about my incorrect suggestion the last time.

> +}
> +
> +static struct ibm_struct auxmac_data = {
> +	.name = "auxmac",
> +};
> +
> +static ssize_t auxmac_show(struct device *dev,
> +			   struct device_attribute *attr,
> +			   char *buf)
> +{
> +	return sysfs_emit(buf, "%s\n", auxmac);
> +}
> +static DEVICE_ATTR_RO(auxmac);
> +
> +static struct attribute *auxmac_attributes[] = {
> +	&dev_attr_auxmac.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group auxmac_attr_group = {
> +	.attrs = auxmac_attributes,
> +};
> +
>  /* --------------------------------------------------------------------- */
>  
>  static struct attribute *tpacpi_driver_attributes[] = {
> @@ -10843,6 +10917,7 @@ static const struct attribute_group *tpacpi_groups[] = {
>  	&proxsensor_attr_group,
>  	&kbdlang_attr_group,
>  	&dprc_attr_group,
> +	&auxmac_attr_group,
>  	NULL,
>  };
>  
> @@ -11414,6 +11489,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
>  		.init = tpacpi_dprc_init,
>  		.data = &dprc_driver_data,
>  	},
> +	{
> +		.init = auxmac_init,
> +		.data = &auxmac_data,
> +	},
>  };
>  
>  static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
> 

-- 
 i.

Re: [PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

[Fernando Eckhardt Valle (FIPT)]

Hi Ilpo,
Thanks for the feedback again!

> Okay, I wasn't expecting this change as this relies on the nul termination
> by strscpy() since the original buffer does not have one but the #
> character there. But I guess it isn't harmful either.
Yes, precisely because strscpy() put the 'nul terminator' I thought it would be ok. In the tests I did, everything always worked fine too.

>  AUXMAC_START is an offset ??? It should be AUXMAC_LEN.
I thought that since the string 'disabled' has length 8, then I would use AUXMAC_START which is defined as 9 , because that way strscpy would copy the 8 characters of 'disabled' + the nul terminator. Wouldn't that be correct? Or would it be better to use AUXMAC_LEN which is defined to 12?

> I only now realized there are two gotos to auxmacinvalid. Therefore, I'd
> do this instead:
2 'goto'... I agree.

Fernando

________________________________________
From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Sent: Friday, September 22, 2023 5:51 AM
To: Fernando Eckhardt Valle (FIPT)
Cc: Hans de Goede; Mark Pearson; corbet@lwn.net; hmh@hmh.eng.br; markgross@kernel.org; linux-doc@vger.kernel.org; LKML; ibm-acpi-devel@lists.sourceforge.net; platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

On Thu, 21 Sep 2023, Fernando Eckhardt Valle wrote:

> Newer Thinkpads have a feature called MAC Address Pass-through.
> This patch provides a sysfs interface that userspace can use
> to get this auxiliary mac address.
>
> Signed-off-by: Fernando Eckhardt Valle <fevalle@ipt.br>
> ---
> Changes in v4:
> - strscpy() in all string copies.
> Changes in v3:
> - Added null terminator to auxmac string when copying auxiliary
> mac address value.
> Changes in v2:
> - Added documentation.
> - All handling of the auxmac value is done in the _init function.
> ---
>  .../admin-guide/laptops/thinkpad-acpi.rst     | 20 +++++
>  drivers/platform/x86/thinkpad_acpi.c          | 79 +++++++++++++++++++
>  2 files changed, 99 insertions(+)
>
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index e27a1c3f6..98d304010 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -53,6 +53,7 @@ detailed description):
>       - Lap mode sensor
>       - Setting keyboard language
>       - WWAN Antenna type
> +     - Auxmac
>
>  A compatibility table by model and feature is maintained on the web
>  site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1511,6 +1512,25 @@ Currently 2 antenna types are supported as mentioned below:
>  The property is read-only. If the platform doesn't have support the sysfs
>  class is not created.
>
> +Auxmac
> +------
> +
> +sysfs: auxmac
> +
> +Some newer Thinkpads have a feature called MAC Address Pass-through. This
> +feature is implemented by the system firmware to provide a system unique MAC,
> +that can override a dock or USB ethernet dongle MAC, when connected to a
> +network. This property enables user-space to easily determine the MAC address
> +if the feature is enabled.
> +
> +The values of this auxiliary MAC are:
> +
> +        cat /sys/devices/platform/thinkpad_acpi/auxmac
> +
> +If the feature is disabled, the value will be 'disabled'.
> +
> +This property is read-only.
> +
>  Adaptive keyboard
>  -----------------
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index d70c89d32..f430cc9ed 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -10785,6 +10785,80 @@ static struct ibm_struct dprc_driver_data = {
>       .name = "dprc",
>  };
>
> +/*
> + * Auxmac
> + *
> + * This auxiliary mac address is enabled in the bios through the
> + * MAC Address Pass-through feature. In most cases, there are three
> + * possibilities: Internal Mac, Second Mac, and disabled.
> + *
> + */
> +
> +#define AUXMAC_LEN 12
> +#define AUXMAC_START 9
> +#define AUXMAC_STRLEN 22
> +#define AUXMAC_BEGIN_MARKER 8
> +#define AUXMAC_END_MARKER 21
> +
> +static char auxmac[AUXMAC_LEN + 1];
> +
> +static int auxmac_init(struct ibm_init_struct *iibm)
> +{
> +     acpi_status status;
> +     struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> +     union acpi_object *obj;
> +
> +     status = acpi_evaluate_object(NULL, "\\MACA", NULL, &buffer);
> +
> +     if (ACPI_FAILURE(status))
> +             return -ENODEV;
> +
> +     obj = buffer.pointer;
> +
> +     if (obj->type != ACPI_TYPE_STRING || obj->string.length != AUXMAC_STRLEN) {
> +             pr_info("Invalid buffer for MAC address pass-through.\n");
> +             strscpy(auxmac, "unavailable", AUXMAC_LEN);
> +             goto auxmacinvalid;
> +     }
> +
> +     if (obj->string.pointer[AUXMAC_BEGIN_MARKER] != '#' ||
> +         obj->string.pointer[AUXMAC_END_MARKER] != '#') {
> +             pr_info("Invalid header for MAC address pass-through.\n");
> +             strscpy(auxmac, "unavailable", AUXMAC_LEN);
> +             goto auxmacinvalid;
> +     }
> +
> +     if (strncmp(obj->string.pointer + AUXMAC_START, "XXXXXXXXXXXX", AUXMAC_LEN) != 0)
> +             strscpy(auxmac, obj->string.pointer + AUXMAC_START, AUXMAC_LEN + 1);

Okay, I wasn't expecting this change as this relies on the nul termination
by strscpy() since the original buffer does not have one but the #
character there. But I guess it isn't harmful either.

> +     else
> +             strscpy(auxmac, "disabled", AUXMAC_START);

AUXMAC_START is an offset ??? It should be AUXMAC_LEN.

> +
> +auxmacinvalid:
> +     kfree(obj);
> +     return 0;

I only now realized there are two gotos to auxmacinvalid. Therefore, I'd
do this instead:

free:
        kfree(obj);
        return 0;
auxmacinvalid:
        strscpy(auxmac, "unavailable", AUXMAC_LEN);
        goto free;

I'm sorry about my incorrect suggestion the last time.

> +}
> +
> +static struct ibm_struct auxmac_data = {
> +     .name = "auxmac",
> +};
> +
> +static ssize_t auxmac_show(struct device *dev,
> +                        struct device_attribute *attr,
> +                        char *buf)
> +{
> +     return sysfs_emit(buf, "%s\n", auxmac);
> +}
> +static DEVICE_ATTR_RO(auxmac);
> +
> +static struct attribute *auxmac_attributes[] = {
> +     &dev_attr_auxmac.attr,
> +     NULL
> +};
> +
> +static const struct attribute_group auxmac_attr_group = {
> +     .attrs = auxmac_attributes,
> +};
> +
>  /* --------------------------------------------------------------------- */
>
>  static struct attribute *tpacpi_driver_attributes[] = {
> @@ -10843,6 +10917,7 @@ static const struct attribute_group *tpacpi_groups[] = {
>       &proxsensor_attr_group,
>       &kbdlang_attr_group,
>       &dprc_attr_group,
> +     &auxmac_attr_group,
>       NULL,
>  };
>
> @@ -11414,6 +11489,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
>               .init = tpacpi_dprc_init,
>               .data = &dprc_driver_data,
>       },
> +     {
> +             .init = auxmac_init,
> +             .data = &auxmac_data,
> +     },
>  };
>
>  static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
>

--
 i.

Re: [PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

[Ilpo Järvinen]

On Fri, 22 Sep 2023, Fernando Eckhardt Valle (FIPT) wrote:

> Thanks for the feedback again!
> 
> > Okay, I wasn't expecting this change as this relies on the nul termination
> > by strscpy() since the original buffer does not have one but the #
> > character there. But I guess it isn't harmful either.
> Yes, precisely because strscpy() put the 'nul terminator' I thought it 
> would be ok. In the tests I did, everything always worked fine too.

It was a bit unorthodox way to take advantage of the way strscpy() works
but like I said, doesn't look harmful.

> >  AUXMAC_START is an offset ??? It should be AUXMAC_LEN.
>
> I thought that since the string 'disabled' has length 8, then I would 
> use AUXMAC_START which is defined as 9 , because that way strscpy would 
> copy the 8 characters of 'disabled' + the nul terminator. Wouldn't that 
> be correct? Or would it be better to use AUXMAC_LEN which is defined to 
> 12? 

strscpy() is takes the size of the destination:

 * @size: Size of destination buffer

...so please use AUXMAC_LEN.

In anycase, "disabled" as the source is itself nul-terminated so strscpy() 
won't copy beyond its length.


-- 
 i.

Re: [PATCH v4] platform/x86: thinkpad_acpi: sysfs interface to auxmac

[Hans de Goede]

Hi,

On 9/21/23 16:36, Fernando Eckhardt Valle wrote:
> Newer Thinkpads have a feature called MAC Address Pass-through.
> This patch provides a sysfs interface that userspace can use
> to get this auxiliary mac address.
> 
> Signed-off-by: Fernando Eckhardt Valle <fevalle@ipt.br>
> ---
> Changes in v4:
> - strscpy() in all string copies.
> Changes in v3:
> - Added null terminator to auxmac string when copying auxiliary
> mac address value.
> Changes in v2:
> - Added documentation.
> - All handling of the auxmac value is done in the _init function.
> ---
>  .../admin-guide/laptops/thinkpad-acpi.rst     | 20 +++++
>  drivers/platform/x86/thinkpad_acpi.c          | 79 +++++++++++++++++++
>  2 files changed, 99 insertions(+)
> 
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index e27a1c3f6..98d304010 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -53,6 +53,7 @@ detailed description):
>  	- Lap mode sensor
>  	- Setting keyboard language
>  	- WWAN Antenna type
> +	- Auxmac
>  
>  A compatibility table by model and feature is maintained on the web
>  site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1511,6 +1512,25 @@ Currently 2 antenna types are supported as mentioned below:
>  The property is read-only. If the platform doesn't have support the sysfs
>  class is not created.
>  
> +Auxmac
> +------
> +
> +sysfs: auxmac
> +
> +Some newer Thinkpads have a feature called MAC Address Pass-through. This
> +feature is implemented by the system firmware to provide a system unique MAC,
> +that can override a dock or USB ethernet dongle MAC, when connected to a
> +network. This property enables user-space to easily determine the MAC address
> +if the feature is enabled.
> +
> +The values of this auxiliary MAC are:
> +
> +        cat /sys/devices/platform/thinkpad_acpi/auxmac
> +
> +If the feature is disabled, the value will be 'disabled'.
> +
> +This property is read-only.
> +
>  Adaptive keyboard
>  -----------------
>  
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index d70c89d32..f430cc9ed 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -10785,6 +10785,80 @@ static struct ibm_struct dprc_driver_data = {
>  	.name = "dprc",
>  };
>  
> +/*
> + * Auxmac
> + *
> + * This auxiliary mac address is enabled in the bios through the
> + * MAC Address Pass-through feature. In most cases, there are three
> + * possibilities: Internal Mac, Second Mac, and disabled.
> + *
> + */
> +
> +#define AUXMAC_LEN 12
> +#define AUXMAC_START 9
> +#define AUXMAC_STRLEN 22
> +#define AUXMAC_BEGIN_MARKER 8
> +#define AUXMAC_END_MARKER 21
> +
> +static char auxmac[AUXMAC_LEN + 1];
> +
> +static int auxmac_init(struct ibm_init_struct *iibm)
> +{
> +	acpi_status status;
> +	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *obj;
> +
> +	status = acpi_evaluate_object(NULL, "\\MACA", NULL, &buffer);
> +
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	obj = buffer.pointer;
> +
> +	if (obj->type != ACPI_TYPE_STRING || obj->string.length != AUXMAC_STRLEN) {
> +		pr_info("Invalid buffer for MAC address pass-through.\n");
> +		strscpy(auxmac, "unavailable", AUXMAC_LEN);

Please use sizeof(auxmac) as last parameter to strscpy() here.

> +		goto auxmacinvalid;
> +	}
> +
> +	if (obj->string.pointer[AUXMAC_BEGIN_MARKER] != '#' ||
> +	    obj->string.pointer[AUXMAC_END_MARKER] != '#') {
> +		pr_info("Invalid header for MAC address pass-through.\n");
> +		strscpy(auxmac, "unavailable", AUXMAC_LEN);

Please use sizeof(auxmac) as last parameter to strscpy() here.


> +		goto auxmacinvalid;
> +	}
> +
> +	if (strncmp(obj->string.pointer + AUXMAC_START, "XXXXXXXXXXXX", AUXMAC_LEN) != 0)
> +		strscpy(auxmac, obj->string.pointer + AUXMAC_START, AUXMAC_LEN + 1);

Please use sizeof(auxmac) as last parameter to strscpy() here.

> +	else
> +		strscpy(auxmac, "disabled", AUXMAC_START);

Please use sizeof(auxmac) as last parameter to strscpy() here.

(using AUXMAC_START here really makes no sense at all)

Regards,

Hans



> +
> +auxmacinvalid:
> +	kfree(obj);
> +	return 0;
> +}
> +
> +static struct ibm_struct auxmac_data = {
> +	.name = "auxmac",
> +};
> +
> +static ssize_t auxmac_show(struct device *dev,
> +			   struct device_attribute *attr,
> +			   char *buf)
> +{
> +	return sysfs_emit(buf, "%s\n", auxmac);
> +}
> +static DEVICE_ATTR_RO(auxmac);
> +
> +static struct attribute *auxmac_attributes[] = {
> +	&dev_attr_auxmac.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group auxmac_attr_group = {
> +	.attrs = auxmac_attributes,
> +};
> +
>  /* --------------------------------------------------------------------- */
>  
>  static struct attribute *tpacpi_driver_attributes[] = {
> @@ -10843,6 +10917,7 @@ static const struct attribute_group *tpacpi_groups[] = {
>  	&proxsensor_attr_group,
>  	&kbdlang_attr_group,
>  	&dprc_attr_group,
> +	&auxmac_attr_group,
>  	NULL,
>  };
>  
> @@ -11414,6 +11489,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
>  		.init = tpacpi_dprc_init,
>  		.data = &dprc_driver_data,
>  	},
> +	{
> +		.init = auxmac_init,
> +		.data = &auxmac_data,
> +	},
>  };
>  
>  static int __init set_ibm_param(const char *val, const struct kernel_param *kp)