xref: /openbmc/linux/security/Kconfig (revision dd0859dc)

#
# Security configuration
#

menu "Security options"

source security/keys/Kconfig

config SECURITY_DMESG_RESTRICT
	bool "Restrict unprivileged access to the kernel syslog"
	default n
	help
	  This enforces restrictions on unprivileged users reading the kernel
	  syslog via dmesg(8).

	  If this option is not selected, no restrictions will be enforced
	  unless the dmesg_restrict sysctl is explicitly set to (1).

	  If you are unsure how to answer this question, answer N.

config SECURITY
	bool "Enable different security models"
	depends on SYSFS
	depends on MULTIUSER
	help
	  This allows you to choose different security modules to be
	  configured into your kernel.

	  If this option is not selected, the default Linux security
	  model will be used.

	  If you are unsure how to answer this question, answer N.

config SECURITY_WRITABLE_HOOKS
	depends on SECURITY
	bool
	default n

config SECURITYFS
	bool "Enable the securityfs filesystem"
	help
	  This will build the securityfs filesystem.  It is currently used by
	  the TPM bios character driver and IMA, an integrity provider.  It is
	  not used by SELinux or SMACK.

	  If you are unsure how to answer this question, answer N.

config SECURITY_NETWORK
	bool "Socket and Networking Security Hooks"
	depends on SECURITY
	help
	  This enables the socket and networking security hooks.
	  If enabled, a security module can use these hooks to
	  implement socket and networking access controls.
	  If you are unsure how to answer this question, answer N.

config SECURITY_NETWORK_XFRM
	bool "XFRM (IPSec) Networking Security Hooks"
	depends on XFRM && SECURITY_NETWORK
	help
	  This enables the XFRM (IPSec) networking security hooks.
	  If enabled, a security module can use these hooks to
	  implement per-packet access controls based on labels
	  derived from IPSec policy.  Non-IPSec communications are
	  designated as unlabelled, and only sockets authorized
	  to communicate unlabelled data can send without using
	  IPSec.
	  If you are unsure how to answer this question, answer N.

config SECURITY_PATH
	bool "Security hooks for pathname based access control"
	depends on SECURITY
	help
	  This enables the security hooks for pathname based access control.
	  If enabled, a security module can use these hooks to
	  implement pathname based access controls.
	  If you are unsure how to answer this question, answer N.

config INTEL_TXT
	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
	depends on HAVE_INTEL_TXT
	help
	  This option enables support for booting the kernel with the
	  Trusted Boot (tboot) module. This will utilize
	  Intel(R) Trusted Execution Technology to perform a measured launch
	  of the kernel. If the system does not support Intel(R) TXT, this
	  will have no effect.

	  Intel TXT will provide higher assurance of system configuration and
	  initial state as well as data reset protection.  This is used to
	  create a robust initial kernel measurement and verification, which
	  helps to ensure that kernel security mechanisms are functioning
	  correctly. This level of protection requires a root of trust outside
	  of the kernel itself.

	  Intel TXT also helps solve real end user concerns about having
	  confidence that their hardware is running the VMM or kernel that
	  it was configured with, especially since they may be responsible for
	  providing such assurances to VMs and services running on it.

	  See <http://www.intel.com/technology/security/> for more information
	  about Intel(R) TXT.
	  See <http://tboot.sourceforge.net> for more information about tboot.
	  See Documentation/intel_txt.txt for a description of how to enable
	  Intel TXT support in a kernel boot.

	  If you are unsure as to whether this is required, answer N.

config LSM_MMAP_MIN_ADDR
	int "Low address space for LSM to protect from user allocation"
	depends on SECURITY && SECURITY_SELINUX
	default 32768 if ARM || (ARM64 && COMPAT)
	default 65536
	help
	  This is the portion of low virtual memory which should be protected
	  from userspace allocation.  Keeping a user from writing to low pages
	  can help reduce the impact of kernel NULL pointer bugs.

	  For most ia64, ppc64 and x86 users with lots of address space
	  a value of 65536 is reasonable and should cause no problems.
	  On arm and other archs it should not be higher than 32768.
	  Programs which use vm86 functionality or have some need to map
	  this low address space will need the permission specific to the
	  systems running LSM.

config HAVE_HARDENED_USERCOPY_ALLOCATOR
	bool
	help
	  The heap allocator implements __check_heap_object() for
	  validating memory ranges against heap object sizes in
	  support of CONFIG_HARDENED_USERCOPY.

config HAVE_ARCH_HARDENED_USERCOPY
	bool
	help
	  The architecture supports CONFIG_HARDENED_USERCOPY by
	  calling check_object_size() just before performing the
	  userspace copies in the low level implementation of
	  copy_to_user() and copy_from_user().

config HARDENED_USERCOPY
	bool "Harden memory copies between kernel and userspace"
	depends on HAVE_ARCH_HARDENED_USERCOPY
	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
	select BUG
	help
	  This option checks for obviously wrong memory regions when
	  copying memory to/from the kernel (via copy_to_user() and
	  copy_from_user() functions) by rejecting memory ranges that
	  are larger than the specified heap object, span multiple
	  separately allocates pages, are not on the process stack,
	  or are part of the kernel text. This kills entire classes
	  of heap overflow exploits and similar kernel memory exposures.

config HARDENED_USERCOPY_PAGESPAN
	bool "Refuse to copy allocations that span multiple pages"
	depends on HARDENED_USERCOPY
	depends on EXPERT
	help
	  When a multi-page allocation is done without __GFP_COMP,
	  hardened usercopy will reject attempts to copy it. There are,
	  however, several cases of this in the kernel that have not all
	  been removed. This config is intended to be used only while
	  trying to find such users.

config STATIC_USERMODEHELPER
	bool "Force all usermode helper calls through a single binary"
	help
	  By default, the kernel can call many different userspace
	  binary programs through the "usermode helper" kernel
	  interface.  Some of these binaries are statically defined
	  either in the kernel code itself, or as a kernel configuration
	  option.  However, some of these are dynamically created at
	  runtime, or can be modified after the kernel has started up.
	  To provide an additional layer of security, route all of these
	  calls through a single executable that can not have its name
	  changed.

	  Note, it is up to this single binary to then call the relevant
	  "real" usermode helper binary, based on the first argument
	  passed to it.  If desired, this program can filter and pick
	  and choose what real programs are called.

	  If you wish for all usermode helper programs are to be
	  disabled, choose this option and then set
	  STATIC_USERMODEHELPER_PATH to an empty string.

config STATIC_USERMODEHELPER_PATH
	string "Path to the static usermode helper binary"
	depends on STATIC_USERMODEHELPER
	default "/sbin/usermode-helper"
	help
	  The binary called by the kernel when any usermode helper
	  program is wish to be run.  The "real" application's name will
	  be in the first argument passed to this program on the command
	  line.

	  If you wish for all usermode helper programs to be disabled,
	  specify an empty string here (i.e. "").

source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig
source security/apparmor/Kconfig
source security/loadpin/Kconfig
source security/yama/Kconfig

source security/integrity/Kconfig

choice
	prompt "Default security module"
	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
	default DEFAULT_SECURITY_DAC

	help
	  Select the security module that will be used by default if the
	  kernel parameter security= is not specified.

	config DEFAULT_SECURITY_SELINUX
		bool "SELinux" if SECURITY_SELINUX=y

	config DEFAULT_SECURITY_SMACK
		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y

	config DEFAULT_SECURITY_TOMOYO
		bool "TOMOYO" if SECURITY_TOMOYO=y

	config DEFAULT_SECURITY_APPARMOR
		bool "AppArmor" if SECURITY_APPARMOR=y

	config DEFAULT_SECURITY_DAC
		bool "Unix Discretionary Access Controls"

endchoice

config DEFAULT_SECURITY
	string
	default "selinux" if DEFAULT_SECURITY_SELINUX
	default "smack" if DEFAULT_SECURITY_SMACK
	default "tomoyo" if DEFAULT_SECURITY_TOMOYO
	default "apparmor" if DEFAULT_SECURITY_APPARMOR
	default "" if DEFAULT_SECURITY_DAC

endmenu