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# 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_PERF_EVENTS_RESTRICT bool "Restrict unprivileged use of performance events" depends on PERF_EVENTS help If you say Y here, the kernel.perf_event_paranoid sysctl will be set to 3 by default, and no unprivileged use of the perf_event_open syscall will be permitted unless it is changed. choice prompt "Allow /proc/pid/mem access override" default PROC_MEM_ALWAYS_FORCE help Traditionally /proc/pid/mem allows users to override memory permissions for users like ptrace, assuming they have ptrace capability. This allows people to limit that - either never override, or require actual active ptrace attachment. Defaults to the traditional behavior (for now) config PROC_MEM_ALWAYS_FORCE bool "Traditional /proc/pid/mem behavior" help This allows /proc/pid/mem accesses to override memory mapping permissions if you have ptrace access rights. config PROC_MEM_FORCE_PTRACE bool "Require active ptrace() use for access override" help This allows /proc/pid/mem accesses to override memory mapping permissions for active ptracers like gdb. config PROC_MEM_NO_FORCE bool "Never" help Never override memory mapping permissions endchoice 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 PAGE_TABLE_ISOLATION bool "Remove the kernel mapping in user mode" default y depends on (X86_64 || X86_PAE) && !UML help This feature reduces the number of hardware side channels by ensuring that the majority of kernel addresses are not mapped into userspace. See Documentation/x86/pti.rst for more details. 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 <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/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/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,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR default "lockdown,yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO default "lockdown,yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor" 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