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 SECURITY_WRITABLE_HOOKS
  36         depends on SECURITY
  37         bool
  38         default n
  39
  40 config SECURITYFS
  41         bool "Enable the securityfs filesystem"
  42         help
  43           This will build the securityfs filesystem.  It is currently used by
  44           various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
  45
  46           If you are unsure how to answer this question, answer N.
  47
  48 config SECURITY_NETWORK
  49         bool "Socket and Networking Security Hooks"
  50         depends on SECURITY
  51         help
  52           This enables the socket and networking security hooks.
  53           If enabled, a security module can use these hooks to
  54           implement socket and networking access controls.
  55           If you are unsure how to answer this question, answer N.
  56
  57 config PAGE_TABLE_ISOLATION
  58         bool "Remove the kernel mapping in user mode"
  59         default y
  60         depends on (X86_64 || X86_PAE) && !UML
  61         help
  62           This feature reduces the number of hardware side channels by
  63           ensuring that the majority of kernel addresses are not mapped
  64           into userspace.
  65
  66           See Documentation/x86/pti.rst for more details.
  67
  68 config SECURITY_INFINIBAND
  69         bool "Infiniband Security Hooks"
  70         depends on SECURITY && INFINIBAND
  71         help
  72           This enables the Infiniband security hooks.
  73           If enabled, a security module can use these hooks to
  74           implement Infiniband access controls.
  75           If you are unsure how to answer this question, answer N.
  76
  77 config SECURITY_NETWORK_XFRM
  78         bool "XFRM (IPSec) Networking Security Hooks"
  79         depends on XFRM && SECURITY_NETWORK
  80         help
  81           This enables the XFRM (IPSec) networking security hooks.
  82           If enabled, a security module can use these hooks to
  83           implement per-packet access controls based on labels
  84           derived from IPSec policy.  Non-IPSec communications are
  85           designated as unlabelled, and only sockets authorized
  86           to communicate unlabelled data can send without using
  87           IPSec.
  88           If you are unsure how to answer this question, answer N.
  89
  90 config SECURITY_PATH
  91         bool "Security hooks for pathname based access control"
  92         depends on SECURITY
  93         help
  94           This enables the security hooks for pathname based access control.
  95           If enabled, a security module can use these hooks to
  96           implement pathname based access controls.
  97           If you are unsure how to answer this question, answer N.
  98
  99 config INTEL_TXT
 100         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
 101         depends on HAVE_INTEL_TXT
 102         help
 103           This option enables support for booting the kernel with the
 104           Trusted Boot (tboot) module. This will utilize
 105           Intel(R) Trusted Execution Technology to perform a measured launch
 106           of the kernel. If the system does not support Intel(R) TXT, this
 107           will have no effect.
 108
 109           Intel TXT will provide higher assurance of system configuration and
 110           initial state as well as data reset protection.  This is used to
 111           create a robust initial kernel measurement and verification, which
 112           helps to ensure that kernel security mechanisms are functioning
 113           correctly. This level of protection requires a root of trust outside
 114           of the kernel itself.
 115
 116           Intel TXT also helps solve real end user concerns about having
 117           confidence that their hardware is running the VMM or kernel that
 118           it was configured with, especially since they may be responsible for
 119           providing such assurances to VMs and services running on it.
 120
 121           See <http://www.intel.com/technology/security/> for more information
 122           about Intel(R) TXT.
 123           See <http://tboot.sourceforge.net> for more information about tboot.
 124           See Documentation/x86/intel_txt.rst for a description of how to enable
 125           Intel TXT support in a kernel boot.
 126
 127           If you are unsure as to whether this is required, answer N.
 128
 129 config LSM_MMAP_MIN_ADDR
 130         int "Low address space for LSM to protect from user allocation"
 131         depends on SECURITY && SECURITY_SELINUX
 132         default 32768 if ARM || (ARM64 && COMPAT)
 133         default 65536
 134         help
 135           This is the portion of low virtual memory which should be protected
 136           from userspace allocation.  Keeping a user from writing to low pages
 137           can help reduce the impact of kernel NULL pointer bugs.
 138
 139           For most ia64, ppc64 and x86 users with lots of address space
 140           a value of 65536 is reasonable and should cause no problems.
 141           On arm and other archs it should not be higher than 32768.
 142           Programs which use vm86 functionality or have some need to map
 143           this low address space will need the permission specific to the
 144           systems running LSM.
 145
 146 config HAVE_HARDENED_USERCOPY_ALLOCATOR
 147         bool
 148         help
 149           The heap allocator implements __check_heap_object() for
 150           validating memory ranges against heap object sizes in
 151           support of CONFIG_HARDENED_USERCOPY.
 152
 153 config HARDENED_USERCOPY
 154         bool "Harden memory copies between kernel and userspace"
 155         depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 156         imply STRICT_DEVMEM
 157         help
 158           This option checks for obviously wrong memory regions when
 159           copying memory to/from the kernel (via copy_to_user() and
 160           copy_from_user() functions) by rejecting memory ranges that
 161           are larger than the specified heap object, span multiple
 162           separately allocated pages, are not on the process stack,
 163           or are part of the kernel text. This kills entire classes
 164           of heap overflow exploits and similar kernel memory exposures.
 165
 166 config HARDENED_USERCOPY_FALLBACK
 167         bool "Allow usercopy whitelist violations to fallback to object size"
 168         depends on HARDENED_USERCOPY
 169         default y
 170         help
 171           This is a temporary option that allows missing usercopy whitelists
 172           to be discovered via a WARN() to the kernel log, instead of
 173           rejecting the copy, falling back to non-whitelisted hardened
 174           usercopy that checks the slab allocation size instead of the
 175           whitelist size. This option will be removed once it seems like
 176           all missing usercopy whitelists have been identified and fixed.
 177           Booting with "slab_common.usercopy_fallback=Y/N" can change
 178           this setting.
 179
 180 config HARDENED_USERCOPY_PAGESPAN
 181         bool "Refuse to copy allocations that span multiple pages"
 182         depends on HARDENED_USERCOPY
 183         depends on EXPERT
 184         help
 185           When a multi-page allocation is done without __GFP_COMP,
 186           hardened usercopy will reject attempts to copy it. There are,
 187           however, several cases of this in the kernel that have not all
 188           been removed. This config is intended to be used only while
 189           trying to find such users.
 190
 191 config FORTIFY_SOURCE
 192         bool "Harden common str/mem functions against buffer overflows"
 193         depends on ARCH_HAS_FORTIFY_SOURCE
 194         help
 195           Detect overflows of buffers in common string and memory functions
 196           where the compiler can determine and validate the buffer sizes.
 197
 198 config STATIC_USERMODEHELPER
 199         bool "Force all usermode helper calls through a single binary"
 200         help
 201           By default, the kernel can call many different userspace
 202           binary programs through the "usermode helper" kernel
 203           interface.  Some of these binaries are statically defined
 204           either in the kernel code itself, or as a kernel configuration
 205           option.  However, some of these are dynamically created at
 206           runtime, or can be modified after the kernel has started up.
 207           To provide an additional layer of security, route all of these
 208           calls through a single executable that can not have its name
 209           changed.
 210
 211           Note, it is up to this single binary to then call the relevant
 212           "real" usermode helper binary, based on the first argument
 213           passed to it.  If desired, this program can filter and pick
 214           and choose what real programs are called.
 215
 216           If you wish for all usermode helper programs are to be
 217           disabled, choose this option and then set
 218           STATIC_USERMODEHELPER_PATH to an empty string.
 219
 220 config STATIC_USERMODEHELPER_PATH
 221         string "Path to the static usermode helper binary"
 222         depends on STATIC_USERMODEHELPER
 223         default "/sbin/usermode-helper"
 224         help
 225           The binary called by the kernel when any usermode helper
 226           program is wish to be run.  The "real" application's name will
 227           be in the first argument passed to this program on the command
 228           line.
 229
 230           If you wish for all usermode helper programs to be disabled,
 231           specify an empty string here (i.e. "").
 232
 233 source "security/selinux/Kconfig"
 234 source "security/smack/Kconfig"
 235 source "security/tomoyo/Kconfig"
 236 source "security/apparmor/Kconfig"
 237 source "security/loadpin/Kconfig"
 238 source "security/yama/Kconfig"
 239 source "security/safesetid/Kconfig"
 240
 241 source "security/integrity/Kconfig"
 242
 243 choice
 244         prompt "First legacy 'major LSM' to be initialized"
 245         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 246         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 247         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 248         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 249         default DEFAULT_SECURITY_DAC
 250
 251         help
 252           This choice is there only for converting CONFIG_DEFAULT_SECURITY
 253           in old kernel configs to CONFIG_LSM in new kernel configs. Don't
 254           change this choice unless you are creating a fresh kernel config,
 255           for this choice will be ignored after CONFIG_LSM has been set.
 256
 257           Selects the legacy "major security module" that will be
 258           initialized first. Overridden by non-default CONFIG_LSM.
 259
 260         config DEFAULT_SECURITY_SELINUX
 261                 bool "SELinux" if SECURITY_SELINUX=y
 262
 263         config DEFAULT_SECURITY_SMACK
 264                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 265
 266         config DEFAULT_SECURITY_TOMOYO
 267                 bool "TOMOYO" if SECURITY_TOMOYO=y
 268
 269         config DEFAULT_SECURITY_APPARMOR
 270                 bool "AppArmor" if SECURITY_APPARMOR=y
 271
 272         config DEFAULT_SECURITY_DAC
 273                 bool "Unix Discretionary Access Controls"
 274
 275 endchoice
 276
 277 config LSM
 278         string "Ordered list of enabled LSMs"
 279         default "yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK
 280         default "yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR
 281         default "yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
 282         default "yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC
 283         default "yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
 284         help
 285           A comma-separated list of LSMs, in initialization order.
 286           Any LSMs left off this list will be ignored. This can be
 287           controlled at boot with the "lsm=" parameter.
 288
 289           If unsure, leave this as the default.
 290
 291 source "security/Kconfig.hardening"
 292
 293 endmenu
 294