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	The selinuxfs "checkreqprot" node allows SELinux to be configured
8	to check the protection requested by userspace for mmap/mprotect
9	calls instead of the actual protection applied by the kernel.
10	This was a compatibility mechanism for legacy userspace and
11	for the READ_IMPLIES_EXEC personality flag.  However, if set to
12	1, it weakens security by allowing mappings to be made executable
13	without authorization by policy.  The default value of checkreqprot
14	at boot was changed starting in Linux v4.4 to 0 (i.e. check the
15	actual protection), and Android and Linux distributions have been
16	explicitly writing a "0" to /sys/fs/selinux/checkreqprot during
17	initialization for some time.  Support for setting checkreqprot to 1
18	will be	removed no sooner than June 2021, at which point the kernel
19	will always cease using checkreqprot internally and will always
20	check the actual protections being applied upon mmap/mprotect calls.
21	The checkreqprot selinuxfs node will remain for backward compatibility
22	but will discard writes of the "0" value and will reject writes of the
23	"1" value when this mechanism is removed.
24