diff options
| author | Stephen Smalley <sds@tycho.nsa.gov> | 2020-01-08 11:24:47 -0500 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2020-02-10 10:49:01 -0500 |
| commit | e9c38f9fc2ccd31befe1bb1605b69213483a15b7 (patch) | |
| tree | 281e142f528909787ffc92dab94acfc0593d9474 /Documentation | |
| parent | 4b36cb773a8153417a080f8025d522322f915aea (diff) | |
Documentation,selinux: deprecate setting checkreqprot to 1
Deprecate setting the SELinux checkreqprot tunable to 1 via kernel
parameter or /sys/fs/selinux/checkreqprot. Setting it to 0 is left
intact for compatibility since Android and some Linux distributions
do so for security and treat an inability to set it as a fatal error.
Eventually setting it to 0 will become a no-op and the kernel will
stop using checkreqprot's value internally altogether.
checkreqprot was originally introduced as a compatibility mechanism
for legacy userspace and 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
for the SECURITY_SELINUX_CHECKREQPROT_VALUE config option was changed
from 1 to 0 in commit 2a35d196c160e3 ("selinux: change
CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE default") and both Android
and Linux distributions began explicitly setting
/sys/fs/selinux/checkreqprot to 0 some time ago.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/obsolete/sysfs-selinux-checkreqprot | 23 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 1 |
2 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/ABI/obsolete/sysfs-selinux-checkreqprot b/Documentation/ABI/obsolete/sysfs-selinux-checkreqprot new file mode 100644 index 000000000000..49ed9c8fd1e5 --- /dev/null +++ b/Documentation/ABI/obsolete/sysfs-selinux-checkreqprot @@ -0,0 +1,23 @@ +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. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index dbc22d684627..ff1428d69b2d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -518,6 +518,7 @@ Default value is set via a kernel config option. Value can be changed at runtime via /sys/fs/selinux/checkreqprot. + Setting checkreqprot to 1 is deprecated. cio_ignore= [S390] See Documentation/s390/common_io.rst for details. |