security/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 #
   3 # Security configuration
   4 #
   5
   6 menu "Security options"
   7
   8 source "security/keys/Kconfig"
   9
  10 config SECURITY_DMESG_RESTRICT
  11         bool "Restrict unprivileged access to the kernel syslog"
  12         default n
  13         help
  14           This enforces restrictions on unprivileged users reading the kernel
  15           syslog via dmesg(8).
  16
  17           If this option is not selected, no restrictions will be enforced
  18           unless the dmesg_restrict sysctl is explicitly set to (1).
  19
  20           If you are unsure how to answer this question, answer N.
  21
  22 config SECURITY
  23         bool "Enable different security models"
  24         depends on SYSFS
  25         depends on MULTIUSER
  26         help
  27           This allows you to choose different security modules to be
  28           configured into your kernel.
  29
  30           If this option is not selected, the default Linux security
  31           model will be used.
  32
  33           If you are unsure how to answer this question, answer N.
  34
  35 config SECURITYFS
  36         bool "Enable the securityfs filesystem"
  37         help
  38           This will build the securityfs filesystem.  It is currently used by
  39           various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
  40
  41           If you are unsure how to answer this question, answer N.
  42
  43 config SECURITY_NETWORK
  44         bool "Socket and Networking Security Hooks"
  45         depends on SECURITY
  46         help
  47           This enables the socket and networking security hooks.
  48           If enabled, a security module can use these hooks to
  49           implement socket and networking access controls.
  50           If you are unsure how to answer this question, answer N.
  51
  52 config SECURITY_INFINIBAND
  53         bool "Infiniband Security Hooks"
  54         depends on SECURITY && INFINIBAND
  55         help
  56           This enables the Infiniband security hooks.
  57           If enabled, a security module can use these hooks to
  58           implement Infiniband access controls.
  59           If you are unsure how to answer this question, answer N.
  60
  61 config SECURITY_NETWORK_XFRM
  62         bool "XFRM (IPSec) Networking Security Hooks"
  63         depends on XFRM && SECURITY_NETWORK
  64         help
  65           This enables the XFRM (IPSec) networking security hooks.
  66           If enabled, a security module can use these hooks to
  67           implement per-packet access controls based on labels
  68           derived from IPSec policy.  Non-IPSec communications are
  69           designated as unlabelled, and only sockets authorized
  70           to communicate unlabelled data can send without using
  71           IPSec.
  72           If you are unsure how to answer this question, answer N.
  73
  74 config SECURITY_PATH
  75         bool "Security hooks for pathname based access control"
  76         depends on SECURITY
  77         help
  78           This enables the security hooks for pathname based access control.
  79           If enabled, a security module can use these hooks to
  80           implement pathname based access controls.
  81           If you are unsure how to answer this question, answer N.
  82
  83 config INTEL_TXT
  84         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
  85         depends on HAVE_INTEL_TXT
  86         help
  87           This option enables support for booting the kernel with the
  88           Trusted Boot (tboot) module. This will utilize
  89           Intel(R) Trusted Execution Technology to perform a measured launch
  90           of the kernel. If the system does not support Intel(R) TXT, this
  91           will have no effect.
  92
  93           Intel TXT will provide higher assurance of system configuration and
  94           initial state as well as data reset protection.  This is used to
  95           create a robust initial kernel measurement and verification, which
  96           helps to ensure that kernel security mechanisms are functioning
  97           correctly. This level of protection requires a root of trust outside
  98           of the kernel itself.
  99
 100           Intel TXT also helps solve real end user concerns about having
 101           confidence that their hardware is running the VMM or kernel that
 102           it was configured with, especially since they may be responsible for
 103           providing such assurances to VMs and services running on it.
 104
 105           See <https://www.intel.com/technology/security/> for more information
 106           about Intel(R) TXT.
 107           See <http://tboot.sourceforge.net> for more information about tboot.
 108           See Documentation/arch/x86/intel_txt.rst for a description of how to enable
 109           Intel TXT support in a kernel boot.
 110
 111           If you are unsure as to whether this is required, answer N.
 112
 113 config LSM_MMAP_MIN_ADDR
 114         int "Low address space for LSM to protect from user allocation"
 115         depends on SECURITY && SECURITY_SELINUX
 116         default 32768 if ARM || (ARM64 && COMPAT)
 117         default 65536
 118         help
 119           This is the portion of low virtual memory which should be protected
 120           from userspace allocation.  Keeping a user from writing to low pages
 121           can help reduce the impact of kernel NULL pointer bugs.
 122
 123           For most ia64, ppc64 and x86 users with lots of address space
 124           a value of 65536 is reasonable and should cause no problems.
 125           On arm and other archs it should not be higher than 32768.
 126           Programs which use vm86 functionality or have some need to map
 127           this low address space will need the permission specific to the
 128           systems running LSM.
 129
 130 config HARDENED_USERCOPY
 131         bool "Harden memory copies between kernel and userspace"
 132         imply STRICT_DEVMEM
 133         help
 134           This option checks for obviously wrong memory regions when
 135           copying memory to/from the kernel (via copy_to_user() and
 136           copy_from_user() functions) by rejecting memory ranges that
 137           are larger than the specified heap object, span multiple
 138           separately allocated pages, are not on the process stack,
 139           or are part of the kernel text. This prevents entire classes
 140           of heap overflow exploits and similar kernel memory exposures.
 141
 142 config FORTIFY_SOURCE
 143         bool "Harden common str/mem functions against buffer overflows"
 144         depends on ARCH_HAS_FORTIFY_SOURCE
 145         # https://github.com/llvm/llvm-project/issues/53645
 146         depends on !CC_IS_CLANG || !X86_32
 147         help
 148           Detect overflows of buffers in common string and memory functions
 149           where the compiler can determine and validate the buffer sizes.
 150
 151 config STATIC_USERMODEHELPER
 152         bool "Force all usermode helper calls through a single binary"
 153         help
 154           By default, the kernel can call many different userspace
 155           binary programs through the "usermode helper" kernel
 156           interface.  Some of these binaries are statically defined
 157           either in the kernel code itself, or as a kernel configuration
 158           option.  However, some of these are dynamically created at
 159           runtime, or can be modified after the kernel has started up.
 160           To provide an additional layer of security, route all of these
 161           calls through a single executable that can not have its name
 162           changed.
 163
 164           Note, it is up to this single binary to then call the relevant
 165           "real" usermode helper binary, based on the first argument
 166           passed to it.  If desired, this program can filter and pick
 167           and choose what real programs are called.
 168
 169           If you wish for all usermode helper programs are to be
 170           disabled, choose this option and then set
 171           STATIC_USERMODEHELPER_PATH to an empty string.
 172
 173 config STATIC_USERMODEHELPER_PATH
 174         string "Path to the static usermode helper binary"
 175         depends on STATIC_USERMODEHELPER
 176         default "/sbin/usermode-helper"
 177         help
 178           The binary called by the kernel when any usermode helper
 179           program is wish to be run.  The "real" application's name will
 180           be in the first argument passed to this program on the command
 181           line.
 182
 183           If you wish for all usermode helper programs to be disabled,
 184           specify an empty string here (i.e. "").
 185
 186 source "security/selinux/Kconfig"
 187 source "security/smack/Kconfig"
 188 source "security/tomoyo/Kconfig"
 189 source "security/apparmor/Kconfig"
 190 source "security/loadpin/Kconfig"
 191 source "security/yama/Kconfig"
 192 source "security/safesetid/Kconfig"
 193 source "security/lockdown/Kconfig"
 194 source "security/landlock/Kconfig"
 195
 196 source "security/integrity/Kconfig"
 197
 198 choice
 199         prompt "First legacy 'major LSM' to be initialized"
 200         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 201         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 202         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 203         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 204         default DEFAULT_SECURITY_DAC
 205
 206         help
 207           This choice is there only for converting CONFIG_DEFAULT_SECURITY
 208           in old kernel configs to CONFIG_LSM in new kernel configs. Don't
 209           change this choice unless you are creating a fresh kernel config,
 210           for this choice will be ignored after CONFIG_LSM has been set.
 211
 212           Selects the legacy "major security module" that will be
 213           initialized first. Overridden by non-default CONFIG_LSM.
 214
 215         config DEFAULT_SECURITY_SELINUX
 216                 bool "SELinux" if SECURITY_SELINUX=y
 217
 218         config DEFAULT_SECURITY_SMACK
 219                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 220
 221         config DEFAULT_SECURITY_TOMOYO
 222                 bool "TOMOYO" if SECURITY_TOMOYO=y
 223
 224         config DEFAULT_SECURITY_APPARMOR
 225                 bool "AppArmor" if SECURITY_APPARMOR=y
 226
 227         config DEFAULT_SECURITY_DAC
 228                 bool "Unix Discretionary Access Controls"
 229
 230 endchoice
 231
 232 config LSM
 233         string "Ordered list of enabled LSMs"
 234         default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
 235         default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
 236         default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
 237         default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
 238         default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
 239         help
 240           A comma-separated list of LSMs, in initialization order.
 241           Any LSMs left off this list, except for those with order
 242           LSM_ORDER_FIRST and LSM_ORDER_LAST, which are always enabled
 243           if selected in the kernel configuration, will be ignored.
 244           This can be controlled at boot with the "lsm=" parameter.
 245
 246           If unsure, leave this as the default.
 247
 248 source "security/Kconfig.hardening"
 249
 250 endmenu
 251