linux-kernel - [PATCH 4/4] media: uvcvideo: Introduce allow_privacy

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Message-Id: <20251117-uvcdynctrl-v1-4-aed70eadf3d8@chromium.org>
Date: Mon, 17 Nov 2025 20:14:19 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hansg@...nel.org>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-usb@...r.kernel.org, Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH 4/4] media: uvcvideo: Introduce allow_privacy_override

Some camera modules have XU controls that can configure the behaviour of
the privacy LED.

Block mapping of those controls, unless the module is configured with
a new parameter: allow_privacy_override.

Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_driver.c |  5 +++++
 drivers/media/usb/uvc/uvc_v4l2.c   | 32 ++++++++++++++++++++++++++++++++
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 include/linux/usb/uvc.h            |  4 ++++
 4 files changed, 42 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 71563d8f4bcf581694ccd4b665ff52b629caa0b6..d50c501121e6f774dfd6cfdb859279e0860d06a5 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -35,6 +35,7 @@ unsigned int uvc_hw_timestamps_param;
 static unsigned int uvc_quirks_param = -1;
 unsigned int uvc_dbg_param;
 unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
+bool uvc_allow_privacy_override_param;
 
 static struct usb_driver uvc_driver;
 
@@ -2473,6 +2474,10 @@ module_param_named(trace, uvc_dbg_param, uint, 0644);
 MODULE_PARM_DESC(trace, "Trace level bitmask");
 module_param_named(timeout, uvc_timeout_param, uint, 0644);
 MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
+module_param_named(allow_privacy_override, uvc_allow_privacy_override_param,
+		   bool, 0644);
+MODULE_PARM_DESC(allow_privacy_override,
+		 "Allow UVCIOC_CTRL_MAP ioctl map privacy related control");
 
 /* ------------------------------------------------------------------------
  * Driver initialization and cleanup
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 03c64b5698bf4331fed8437fa6e9c726a07450bd..e067b8f38500299fe6acc7e3b9770f7374748823 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -18,6 +18,7 @@
 #include <linux/mm.h>
 #include <linux/wait.h>
 #include <linux/atomic.h>
+#include <linux/usb/uvc.h>
 
 #include <media/v4l2-common.h>
 #include <media/v4l2-ctrls.h>
@@ -121,6 +122,32 @@ static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
 /* ------------------------------------------------------------------------
  * UVC ioctls
  */
+
+static bool uvc_is_privacy_mapping(struct uvc_xu_control_mapping *xmap)
+{
+	struct mapping {
+		u8 entity[16];
+		u8 selector;
+	} privacy_mappings[] = {
+		{
+			.entity = UVC_GUID_LOGITECH_USER_HW_CONTROL_V1,
+			.selector = 1,
+		},
+		{
+			.entity = UVC_GUID_LOGITECH_PERIPHERAL,
+			.selector = 9,
+		},
+	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(privacy_mappings); i++)
+		if (!memcmp(xmap->entity, privacy_mappings[i].entity, 16) &&
+		    xmap->selector == privacy_mappings[i].selector)
+			return true;
+
+	return false;
+}
+
 static int uvc_ioctl_xu_ctrl_map(struct uvc_video_chain *chain,
 				 struct uvc_xu_control_mapping *xmap)
 {
@@ -133,6 +160,11 @@ static int uvc_ioctl_xu_ctrl_map(struct uvc_video_chain *chain,
 		return -EINVAL;
 	}
 
+	if (uvc_is_privacy_mapping(xmap) && !uvc_allow_privacy_override_param) {
+		pr_warn_once("uvcvideo: Privacy related controls can only be mapped if param allow_privacy_override is true\n");
+		return -EINVAL;
+	}
+
 	map = kzalloc(sizeof(*map), GFP_KERNEL);
 	if (map == NULL)
 		return -ENOMEM;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 9a86d7f1f6ea022dace87614030bf0fde0d260f0..1895e4fe45e9c0246b7f0613dd2bc51f60b78759 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -662,6 +662,7 @@ extern unsigned int uvc_clock_param;
 extern unsigned int uvc_dbg_param;
 extern unsigned int uvc_timeout_param;
 extern unsigned int uvc_hw_timestamps_param;
+extern bool uvc_allow_privacy_override_param;
 
 #define uvc_dbg(_dev, flag, fmt, ...)					\
 do {									\
diff --git a/include/linux/usb/uvc.h b/include/linux/usb/uvc.h
index b939a01da11466747249c64c72a3ea40cd364a59..f2d6cf52427ce9c0a62a80ca3629c6e350fa02c8 100644
--- a/include/linux/usb/uvc.h
+++ b/include/linux/usb/uvc.h
@@ -41,6 +41,10 @@
 #define UVC_GUID_LOGITECH_PERIPHERAL \
 	{0x21, 0x2d, 0xe5, 0xff, 0x30, 0x80, 0x2c, 0x4e, \
 	 0x82, 0xd9, 0xf5, 0x87, 0xd0, 0x05, 0x40, 0xbd }
+#define UVC_GUID_LOGITECH_USER_HW_CONTROL_V1 \
+	{0x82, 0x06, 0x61, 0x63, 0x70, 0x50, 0xab, 0x49, \
+	 0xb8, 0xcc, 0xb3, 0x85, 0x5e, 0x8d, 0x22, 0x1f }
+
 
 /* https://learn.microsoft.com/en-us/windows-hardware/drivers/stream/uvc-extensions-1-5#222-extension-unit-controls */
 #define UVC_MSXU_CONTROL_FOCUS			0x01

-- 
2.52.0.rc1.455.g30608eb744-goog