# SPDX-License-Identifier: GPL-2.0-only
#
# 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
various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
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_INFINIBAND
bool "Infiniband Security Hooks"
depends on SECURITY && INFINIBAND
help
This enables the Infiniband security hooks.
If enabled, a security module can use these hooks to
implement Infiniband 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 for more information
about Intel(R) TXT.
See for more information about tboot.
See Documentation/x86/intel_txt.rst 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 HARDENED_USERCOPY
bool "Harden memory copies between kernel and userspace"
depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
imply STRICT_DEVMEM
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 allocated 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_FALLBACK
bool "Allow usercopy whitelist violations to fallback to object size"
depends on HARDENED_USERCOPY
default y
help
This is a temporary option that allows missing usercopy whitelists
to be discovered via a WARN() to the kernel log, instead of
rejecting the copy, falling back to non-whitelisted hardened
usercopy that checks the slab allocation size instead of the
whitelist size. This option will be removed once it seems like
all missing usercopy whitelists have been identified and fixed.
Booting with "slab_common.usercopy_fallback=Y/N" can change
this setting.
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 FORTIFY_SOURCE
bool "Harden common str/mem functions against buffer overflows"
depends on ARCH_HAS_FORTIFY_SOURCE
# https://bugs.llvm.org/show_bug.cgi?id=50322
# https://bugs.llvm.org/show_bug.cgi?id=41459
depends on !CC_IS_CLANG
help
Detect overflows of buffers in common string and memory functions
where the compiler can determine and validate the buffer sizes.
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/safesetid/Kconfig"
source "security/lockdown/Kconfig"
source "security/hookmanager/Kconfig"
source "security/integrity/Kconfig"
choice
prompt "First legacy 'major LSM' to be initialized"
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
This choice is there only for converting CONFIG_DEFAULT_SECURITY
in old kernel configs to CONFIG_LSM in new kernel configs. Don't
change this choice unless you are creating a fresh kernel config,
for this choice will be ignored after CONFIG_LSM has been set.
Selects the legacy "major security module" that will be
initialized first. Overridden by non-default CONFIG_LSM.
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 LSM
string "Ordered list of enabled LSMs"
default "lockdown,yama,hookmanager,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
default "lockdown,yama,hookmanager,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
default "lockdown,yama,hookmanager,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
default "lockdown,yama,hookmanager,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
default "lockdown,yama,hookmanager,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
help
A comma-separated list of LSMs, in initialization order.
Any LSMs left off this list will be ignored. This can be
controlled at boot with the "lsm=" parameter.
If unsure, leave this as the default.
source "security/Kconfig.hardening"
endmenu