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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
commitf4cdf7ca9a1fdcca413157df19753f388a5a224e (patch)
tree60a31895b2446cd7fa27514e8c2843534a0de0da /Documentation/usb/usbdevfs-drop-permissions.c
downloadlinux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz
linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ...
Diffstat (limited to 'Documentation/usb/usbdevfs-drop-permissions.c')
-rw-r--r--Documentation/usb/usbdevfs-drop-permissions.c120
1 files changed, 120 insertions, 0 deletions
diff --git a/Documentation/usb/usbdevfs-drop-permissions.c b/Documentation/usb/usbdevfs-drop-permissions.c
new file mode 100644
index 000000000..6b8da6ef0
--- /dev/null
+++ b/Documentation/usb/usbdevfs-drop-permissions.c
@@ -0,0 +1,120 @@
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <inttypes.h>
+#include <unistd.h>
+
+#include <linux/usbdevice_fs.h>
+
+/* For building without an updated set of headers */
+#ifndef USBDEVFS_DROP_PRIVILEGES
+#define USBDEVFS_DROP_PRIVILEGES _IOW('U', 30, __u32)
+#define USBDEVFS_CAP_DROP_PRIVILEGES 0x40
+#endif
+
+void drop_privileges(int fd, uint32_t mask)
+{
+ int res;
+
+ res = ioctl(fd, USBDEVFS_DROP_PRIVILEGES, &mask);
+ if (res)
+ printf("ERROR: USBDEVFS_DROP_PRIVILEGES returned %d\n", res);
+ else
+ printf("OK: privileges dropped!\n");
+}
+
+void reset_device(int fd)
+{
+ int res;
+
+ res = ioctl(fd, USBDEVFS_RESET);
+ if (!res)
+ printf("OK: USBDEVFS_RESET succeeded\n");
+ else
+ printf("ERROR: reset failed! (%d - %s)\n",
+ -res, strerror(-res));
+}
+
+void claim_some_intf(int fd)
+{
+ int i, res;
+
+ for (i = 0; i < 4; i++) {
+ res = ioctl(fd, USBDEVFS_CLAIMINTERFACE, &i);
+ if (!res)
+ printf("OK: claimed if %d\n", i);
+ else
+ printf("ERROR claiming if %d (%d - %s)\n",
+ i, -res, strerror(-res));
+ }
+}
+
+int main(int argc, char *argv[])
+{
+ uint32_t mask, caps;
+ int c, fd;
+
+ fd = open(argv[1], O_RDWR);
+ if (fd < 0) {
+ printf("Failed to open file\n");
+ goto err_fd;
+ }
+
+ /*
+ * check if dropping privileges is supported,
+ * bail on systems where the capability is not present
+ */
+ ioctl(fd, USBDEVFS_GET_CAPABILITIES, &caps);
+ if (!(caps & USBDEVFS_CAP_DROP_PRIVILEGES)) {
+ printf("DROP_PRIVILEGES not supported\n");
+ goto err;
+ }
+
+ /*
+ * Drop privileges but keep the ability to claim all
+ * free interfaces (i.e., those not used by kernel drivers)
+ */
+ drop_privileges(fd, -1U);
+
+ printf("Available options:\n"
+ "[0] Exit now\n"
+ "[1] Reset device. Should fail if device is in use\n"
+ "[2] Claim 4 interfaces. Should succeed where not in use\n"
+ "[3] Narrow interface permission mask\n"
+ "Which option shall I run?: ");
+
+ while (scanf("%d", &c) == 1) {
+ switch (c) {
+ case 0:
+ goto exit;
+ case 1:
+ reset_device(fd);
+ break;
+ case 2:
+ claim_some_intf(fd);
+ break;
+ case 3:
+ printf("Insert new mask: ");
+ scanf("%x", &mask);
+ drop_privileges(fd, mask);
+ break;
+ default:
+ printf("I don't recognize that\n");
+ }
+
+ printf("Which test shall I run next?: ");
+ }
+
+exit:
+ close(fd);
+ return 0;
+
+err:
+ close(fd);
+err_fd:
+ return 1;
+}