| What: /sys/fs/selinux/checkreqprot |
| Date: April 2005 (predates git) |
| KernelVersion: 2.6.12-rc2 (predates git) |
| Contact: selinux@vger.kernel.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 in a future kernel release, 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. |
