1What: /sys/fs/selinux/checkreqprot 2Date: April 2005 (predates git) 3KernelVersion: 2.6.12-rc2 (predates git) 4Contact: selinux@vger.kernel.org 5Description: 6 7 REMOVAL UPDATE: The SELinux checkreqprot functionality was removed in 8 March 2023, the original deprecation notice is shown below. 9 10 The selinuxfs "checkreqprot" node allows SELinux to be configured 11 to check the protection requested by userspace for mmap/mprotect 12 calls instead of the actual protection applied by the kernel. 13 This was a compatibility mechanism for legacy userspace and 14 for the READ_IMPLIES_EXEC personality flag. However, if set to 15 1, it weakens security by allowing mappings to be made executable 16 without authorization by policy. The default value of checkreqprot 17 at boot was changed starting in Linux v4.4 to 0 (i.e. check the 18 actual protection), and Android and Linux distributions have been 19 explicitly writing a "0" to /sys/fs/selinux/checkreqprot during 20 initialization for some time. Support for setting checkreqprot to 1 21 will be removed no sooner than June 2021, at which point the kernel 22 will always cease using checkreqprot internally and will always 23 check the actual protections being applied upon mmap/mprotect calls. 24 The checkreqprot selinuxfs node will remain for backward compatibility 25 but will discard writes of the "0" value and will reject writes of the 26 "1" value when this mechanism is removed. 27