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e9c38f9fc2
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 2a35d196c1 ("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>
117 lines
4.5 KiB
Text
117 lines
4.5 KiB
Text
# SPDX-License-Identifier: GPL-2.0-only
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config SECURITY_SELINUX
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bool "NSA SELinux Support"
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depends on SECURITY_NETWORK && AUDIT && NET && INET
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select NETWORK_SECMARK
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default n
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help
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This selects NSA Security-Enhanced Linux (SELinux).
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You will also need a policy configuration and a labeled filesystem.
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If you are unsure how to answer this question, answer N.
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config SECURITY_SELINUX_BOOTPARAM
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bool "NSA SELinux boot parameter"
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depends on SECURITY_SELINUX
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default n
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help
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This option adds a kernel parameter 'selinux', which allows SELinux
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to be disabled at boot. If this option is selected, SELinux
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functionality can be disabled with selinux=0 on the kernel
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command line. The purpose of this option is to allow a single
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kernel image to be distributed with SELinux built in, but not
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necessarily enabled.
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If you are unsure how to answer this question, answer N.
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config SECURITY_SELINUX_DISABLE
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bool "NSA SELinux runtime disable"
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depends on SECURITY_SELINUX
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select SECURITY_WRITABLE_HOOKS
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default n
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help
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This option enables writing to a selinuxfs node 'disable', which
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allows SELinux to be disabled at runtime prior to the policy load.
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SELinux will then remain disabled until the next boot.
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This option is similar to the selinux=0 boot parameter, but is to
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support runtime disabling of SELinux, e.g. from /sbin/init, for
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portability across platforms where boot parameters are difficult
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to employ.
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NOTE: selecting this option will disable the '__ro_after_init'
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kernel hardening feature for security hooks. Please consider
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using the selinux=0 boot parameter instead of enabling this
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option.
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WARNING: this option is deprecated and will be removed in a future
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kernel release.
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If you are unsure how to answer this question, answer N.
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config SECURITY_SELINUX_DEVELOP
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bool "NSA SELinux Development Support"
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depends on SECURITY_SELINUX
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default y
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help
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This enables the development support option of NSA SELinux,
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which is useful for experimenting with SELinux and developing
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policies. If unsure, say Y. With this option enabled, the
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kernel will start in permissive mode (log everything, deny nothing)
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unless you specify enforcing=1 on the kernel command line. You
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can interactively toggle the kernel between enforcing mode and
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permissive mode (if permitted by the policy) via
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/sys/fs/selinux/enforce.
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config SECURITY_SELINUX_AVC_STATS
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bool "NSA SELinux AVC Statistics"
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depends on SECURITY_SELINUX
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default y
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help
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This option collects access vector cache statistics to
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/sys/fs/selinux/avc/cache_stats, which may be monitored via
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tools such as avcstat.
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config SECURITY_SELINUX_CHECKREQPROT_VALUE
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int "NSA SELinux checkreqprot default value"
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depends on SECURITY_SELINUX
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range 0 1
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default 0
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help
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This option sets the default value for the 'checkreqprot' flag
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that determines whether SELinux checks the protection requested
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by the application or the protection that will be applied by the
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kernel (including any implied execute for read-implies-exec) for
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mmap and mprotect calls. If this option is set to 0 (zero),
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SELinux will default to checking the protection that will be applied
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by the kernel. If this option is set to 1 (one), SELinux will
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default to checking the protection requested by the application.
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The checkreqprot flag may be changed from the default via the
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'checkreqprot=' boot parameter. It may also be changed at runtime
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via /sys/fs/selinux/checkreqprot if authorized by policy.
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WARNING: this option is deprecated and will be removed in a future
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kernel release.
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If you are unsure how to answer this question, answer 0.
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config SECURITY_SELINUX_SIDTAB_HASH_BITS
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int "NSA SELinux sidtab hashtable size"
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depends on SECURITY_SELINUX
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range 8 13
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default 9
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help
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This option sets the number of buckets used in the sidtab hashtable
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to 2^SECURITY_SELINUX_SIDTAB_HASH_BITS buckets. The number of hash
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collisions may be viewed at /sys/fs/selinux/ss/sidtab_hash_stats. If
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chain lengths are high (e.g. > 20) then selecting a higher value here
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will ensure that lookups times are short and stable.
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config SECURITY_SELINUX_SID2STR_CACHE_SIZE
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int "NSA SELinux SID to context string translation cache size"
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depends on SECURITY_SELINUX
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default 256
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help
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This option defines the size of the internal SID -> context string
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cache, which improves the performance of context to string
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conversion. Setting this option to 0 disables the cache completely.
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If unsure, keep the default value.
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