What: /sys/fs/selinux/checkreqprot Date: April 2005 (predates git) KernelVersion: 2.6.12-rc2 (predates git) Contact: firstname.lastname@example.org Description: The selinuxfs "checkreqprot" node allows SELinux to be configured to check the protection requested by userspace for mmap/mprotect calls instead of the actual protection applied by the kernel. This was a compatibility mechanism for legacy userspace and for the READ_IMPLIES_EXEC personality flag. However, if set to 1, it weakens security by allowing mappings to be made executable without authorization by policy. The default value of checkreqprot at boot was changed starting in Linux v4.4 to 0 (i.e. check the actual protection), and Android and Linux distributions have been explicitly writing a "0" to /sys/fs/selinux/checkreqprot during initialization for some time. Support for setting checkreqprot to 1 will be removed no sooner than June 2021, at which point the kernel will always cease using checkreqprot internally and will always check the actual protections being applied upon mmap/mprotect calls. The checkreqprot selinuxfs node will remain for backward compatibility but will discard writes of the "0" value and will reject writes of the "1" value when this mechanism is removed.