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Device drivers may decide to not load firmware when probed to avoid slowing down the boot process should the firmware filesystem not be available yet. In this case, the firmware loading request may be done when a device file associated with the driver is first accessed. The credentials of the userspace process accessing the device file may be used to validate access to the firmware files requested by the driver. Ensure that the kernel assumes the responsibility of reading the firmware. This was observed on Android for a graphic driver loading their firmware when the device file (e.g. /dev/mali0) was first opened by userspace (i.e. surfaceflinger). The security context of surfaceflinger was used to validate the access to the firmware file (e.g. /vendor/firmware/mali.bin). Because previous configurations were relying on the userspace fallback mechanism, the security context of the userspace daemon (i.e. ueventd) was consistently used to read firmware files. More devices are found to use the command line argument firmware_class.path which gives the kernel the opportunity to read the firmware directly, hence surfacing this misattribution. Signed-off-by: Thiébaud Weksteen <tweek@google.com> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Tested-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/r/20220422013215.2301793-1-tweek@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| builtin | ||
| fallback.c | ||
| fallback.h | ||
| fallback_platform.c | ||
| fallback_table.c | ||
| firmware.h | ||
| Kconfig | ||
| main.c | ||
| Makefile | ||