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Message-Id: <20251119-uvcdynctrl-v2-5-0359ffb98c9e@chromium.org>
Date: Wed, 19 Nov 2025 19:37:14 +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 v2 5/6] media: uvcvideo: Introduce allow_privacy_override
param
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.
This is just an interim solution. Based on the users feedback, we will
either put the privacy controls behind a CONFIG option, or completely
block them.
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
drivers/media/usb/uvc/uvc_ctrl.c | 38 ++++++++++++++++++++++++++++++++++++++
drivers/media/usb/uvc/uvc_driver.c | 20 ++++++++++++++++++++
drivers/media/usb/uvc/uvc_v4l2.c | 7 +++++++
drivers/media/usb/uvc/uvcvideo.h | 2 ++
include/linux/usb/uvc.h | 4 ++++
5 files changed, 71 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 57ce486f22bbc404a1f127539eb2d12373431631..d9cbb942f798dc7138608982a5d3e3ef9f8141f6 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -2951,6 +2951,35 @@ static int uvc_ctrl_init_xu_ctrl(struct uvc_device *dev,
return ret;
}
+bool uvc_ctrl_is_privacy_control(u8 entity[16], u8 selector)
+{
+ /*
+ * This list is not exhaustive, it is a best effort to block access to
+ * non documented controls that can affect user's privacy.
+ */
+ struct privacy_control {
+ u8 entity[16];
+ u8 selector;
+ } privacy_control[] = {
+ {
+ .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_control); i++)
+ if (!memcmp(entity, privacy_control[i].entity, 16) &&
+ selector == privacy_control[i].selector)
+ return true;
+
+ return false;
+}
+
int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
struct uvc_xu_control_query *xqry)
{
@@ -2995,6 +3024,15 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
return -ENOENT;
}
+ if (uvc_ctrl_is_privacy_control(entity->guid, xqry->selector) &&
+ !uvc_allow_privacy_override_param) {
+ dev_warn_once(&chain->dev->intf->dev,
+ "Privacy related controls can only be accessed if param allow_privacy_override is true\n");
+ uvc_dbg(chain->dev, CONTROL, "Blocking access to privacy related Control %pUl/%u\n",
+ entity->guid, xqry->selector);
+ return -EACCES;
+ }
+
if (mutex_lock_interruptible(&chain->ctrl_mutex))
return -ERESTARTSYS;
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 71563d8f4bcf581694ccd4b665ff52b629caa0b6..c292bf8b6f57e9fdacee726285f5b46e638fd317 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;
@@ -2474,6 +2475,25 @@ MODULE_PARM_DESC(trace, "Trace level bitmask");
module_param_named(timeout, uvc_timeout_param, uint, 0644);
MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
+static int param_set_privacy(const char *val, const struct kernel_param *kp)
+{
+ pr_warn_once("uvcvideo: " DEPRECATED
+ "allow_privacy_override parameter will be eventually removed.\n");
+ return param_set_bool(val, kp);
+}
+
+static const struct kernel_param_ops param_ops_privacy = {
+ .set = param_set_privacy,
+ .get = param_get_bool,
+};
+
+param_check_bool(allow_privacy_override, &uvc_allow_privacy_override_param);
+module_param_cb(allow_privacy_override, ¶m_ops_privacy,
+ &uvc_allow_privacy_override_param, 0644);
+__MODULE_PARM_TYPE(allow_privacy_override, "bool");
+MODULE_PARM_DESC(allow_privacy_override,
+ "Allow access to privacy related controls");
+
/* ------------------------------------------------------------------------
* Driver initialization and cleanup
*/
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 03c64b5698bf4331fed8437fa6e9c726a07450bd..510cf47c86a62ba7fe3c7fa51be82c996cf37f9f 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -133,6 +133,13 @@ static int uvc_ioctl_xu_ctrl_map(struct uvc_video_chain *chain,
return -EINVAL;
}
+ if (uvc_ctrl_is_privacy_control(xmap->entity, xmap->selector) &&
+ !uvc_allow_privacy_override_param) {
+ dev_warn_once(&chain->dev->intf->dev,
+ "Privacy related controls can only be mapped if param allow_privacy_override is true\n");
+ return -EACCES;
+ }
+
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..4b1a70e3100bbf2180411a865a89952a81d0f0a4 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 { \
@@ -792,6 +793,7 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
struct uvc_xu_control_query *xqry);
void uvc_ctrl_cleanup_fh(struct uvc_fh *handle);
+bool uvc_ctrl_is_privacy_control(u8 entity[16], u8 selector);
/* Utility functions */
struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts,
diff --git a/include/linux/usb/uvc.h b/include/linux/usb/uvc.h
index dea23aabbad48270c807463c1a7e1c0d1b79fc1f..70c2a7d2523611418aba363328f76667d379b571 100644
--- a/include/linux/usb/uvc.h
+++ b/include/linux/usb/uvc.h
@@ -49,6 +49,10 @@
#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
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