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