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_PERF_EVENTS_RESTRICT
  23         bool "Restrict unprivileged use of performance events"
  24         depends on PERF_EVENTS
  25         help
  26           If you say Y here, the kernel.perf_event_paranoid sysctl
  27           will be set to 3 by default, and no unprivileged use of the
  28           perf_event_open syscall will be permitted unless it is
  29           changed.
  30
  31 config SECURITY
  32         bool "Enable different security models"
  33         depends on SYSFS
  34         depends on MULTIUSER
  35         help
  36           This allows you to choose different security modules to be
  37           configured into your kernel.
  38
  39           If this option is not selected, the default Linux security
  40           model will be used.
  41
  42           If you are unsure how to answer this question, answer N.
  43
  44 config SECURITY_WRITABLE_HOOKS
  45         depends on SECURITY
  46         bool
  47         default n
  48
  49 config SECURITYFS
  50         bool "Enable the securityfs filesystem"
  51         help
  52           This will build the securityfs filesystem.  It is currently used by
  53           various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
  54
  55           If you are unsure how to answer this question, answer N.
  56
  57 config SECURITY_NETWORK
  58         bool "Socket and Networking Security Hooks"
  59         depends on SECURITY
  60         help
  61           This enables the socket and networking security hooks.
  62           If enabled, a security module can use these hooks to
  63           implement socket and networking access controls.
  64           If you are unsure how to answer this question, answer N.
  65
  66 config SECURITY_INFINIBAND
  67         bool "Infiniband Security Hooks"
  68         depends on SECURITY && INFINIBAND
  69         help
  70           This enables the Infiniband security hooks.
  71           If enabled, a security module can use these hooks to
  72           implement Infiniband access controls.
  73           If you are unsure how to answer this question, answer N.
  74
  75 config SECURITY_NETWORK_XFRM
  76         bool "XFRM (IPSec) Networking Security Hooks"
  77         depends on XFRM && SECURITY_NETWORK
  78         help
  79           This enables the XFRM (IPSec) networking security hooks.
  80           If enabled, a security module can use these hooks to
  81           implement per-packet access controls based on labels
  82           derived from IPSec policy.  Non-IPSec communications are
  83           designated as unlabelled, and only sockets authorized
  84           to communicate unlabelled data can send without using
  85           IPSec.
  86           If you are unsure how to answer this question, answer N.
  87
  88 config SECURITY_PATH
  89         bool "Security hooks for pathname based access control"
  90         depends on SECURITY
  91         help
  92           This enables the security hooks for pathname based access control.
  93           If enabled, a security module can use these hooks to
  94           implement pathname based access controls.
  95           If you are unsure how to answer this question, answer N.
  96
  97 config INTEL_TXT
  98         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
  99         depends on HAVE_INTEL_TXT
 100         help
 101           This option enables support for booting the kernel with the
 102           Trusted Boot (tboot) module. This will utilize
 103           Intel(R) Trusted Execution Technology to perform a measured launch
 104           of the kernel. If the system does not support Intel(R) TXT, this
 105           will have no effect.
 106
 107           Intel TXT will provide higher assurance of system configuration and
 108           initial state as well as data reset protection.  This is used to
 109           create a robust initial kernel measurement and verification, which
 110           helps to ensure that kernel security mechanisms are functioning
 111           correctly. This level of protection requires a root of trust outside
 112           of the kernel itself.
 113
 114           Intel TXT also helps solve real end user concerns about having
 115           confidence that their hardware is running the VMM or kernel that
 116           it was configured with, especially since they may be responsible for
 117           providing such assurances to VMs and services running on it.
 118
 119           See <https://www.intel.com/technology/security/> for more information
 120           about Intel(R) TXT.
 121           See <http://tboot.sourceforge.net> for more information about tboot.
 122           See Documentation/x86/intel_txt.rst for a description of how to enable
 123           Intel TXT support in a kernel boot.
 124
 125           If you are unsure as to whether this is required, answer N.
 126
 127 config LSM_MMAP_MIN_ADDR
 128         int "Low address space for LSM to protect from user allocation"
 129         depends on SECURITY && SECURITY_SELINUX
 130         default 32768 if ARM || (ARM64 && COMPAT)
 131         default 65536
 132         help
 133           This is the portion of low virtual memory which should be protected
 134           from userspace allocation.  Keeping a user from writing to low pages
 135           can help reduce the impact of kernel NULL pointer bugs.
 136
 137           For most ia64, ppc64 and x86 users with lots of address space
 138           a value of 65536 is reasonable and should cause no problems.
 139           On arm and other archs it should not be higher than 32768.
 140           Programs which use vm86 functionality or have some need to map
 141           this low address space will need the permission specific to the
 142           systems running LSM.
 143
 144 config HAVE_HARDENED_USERCOPY_ALLOCATOR
 145         bool
 146         help
 147           The heap allocator implements __check_heap_object() for
 148           validating memory ranges against heap object sizes in
 149           support of CONFIG_HARDENED_USERCOPY.
 150
 151 config HARDENED_USERCOPY
 152         bool "Harden memory copies between kernel and userspace"
 153         depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 154         imply STRICT_DEVMEM
 155         help
 156           This option checks for obviously wrong memory regions when
 157           copying memory to/from the kernel (via copy_to_user() and
 158           copy_from_user() functions) by rejecting memory ranges that
 159           are larger than the specified heap object, span multiple
 160           separately allocated pages, are not on the process stack,
 161           or are part of the kernel text. This kills entire classes
 162           of heap overflow exploits and similar kernel memory exposures.
 163
 164 config HARDENED_USERCOPY_FALLBACK
 165         bool "Allow usercopy whitelist violations to fallback to object size"
 166         depends on HARDENED_USERCOPY
 167         default y
 168         help
 169           This is a temporary option that allows missing usercopy whitelists
 170           to be discovered via a WARN() to the kernel log, instead of
 171           rejecting the copy, falling back to non-whitelisted hardened
 172           usercopy that checks the slab allocation size instead of the
 173           whitelist size. This option will be removed once it seems like
 174           all missing usercopy whitelists have been identified and fixed.
 175           Booting with "slab_common.usercopy_fallback=Y/N" can change
 176           this setting.
 177
 178 config HARDENED_USERCOPY_PAGESPAN
 179         bool "Refuse to copy allocations that span multiple pages"
 180         depends on HARDENED_USERCOPY
 181         depends on EXPERT
 182         help
 183           When a multi-page allocation is done without __GFP_COMP,
 184           hardened usercopy will reject attempts to copy it. There are,
 185           however, several cases of this in the kernel that have not all
 186           been removed. This config is intended to be used only while
 187           trying to find such users.
 188
 189 config FORTIFY_SOURCE
 190         bool "Harden common str/mem functions against buffer overflows"
 191         depends on ARCH_HAS_FORTIFY_SOURCE
 192         # https://bugs.llvm.org/show_bug.cgi?id=50322
 193         # https://bugs.llvm.org/show_bug.cgi?id=41459
 194         depends on !CC_IS_CLANG
 195         help
 196           Detect overflows of buffers in common string and memory functions
 197           where the compiler can determine and validate the buffer sizes.
 198
 199 config STATIC_USERMODEHELPER
 200         bool "Force all usermode helper calls through a single binary"
 201         help
 202           By default, the kernel can call many different userspace
 203           binary programs through the "usermode helper" kernel
 204           interface.  Some of these binaries are statically defined
 205           either in the kernel code itself, or as a kernel configuration
 206           option.  However, some of these are dynamically created at
 207           runtime, or can be modified after the kernel has started up.
 208           To provide an additional layer of security, route all of these
 209           calls through a single executable that can not have its name
 210           changed.
 211
 212           Note, it is up to this single binary to then call the relevant
 213           "real" usermode helper binary, based on the first argument
 214           passed to it.  If desired, this program can filter and pick
 215           and choose what real programs are called.
 216
 217           If you wish for all usermode helper programs are to be
 218           disabled, choose this option and then set
 219           STATIC_USERMODEHELPER_PATH to an empty string.
 220
 221 config STATIC_USERMODEHELPER_PATH
 222         string "Path to the static usermode helper binary"
 223         depends on STATIC_USERMODEHELPER
 224         default "/sbin/usermode-helper"
 225         help
 226           The binary called by the kernel when any usermode helper
 227           program is wish to be run.  The "real" application's name will
 228           be in the first argument passed to this program on the command
 229           line.
 230
 231           If you wish for all usermode helper programs to be disabled,
 232           specify an empty string here (i.e. "").
 233
 234 source "security/selinux/Kconfig"
 235 source "security/smack/Kconfig"
 236 source "security/tomoyo/Kconfig"
 237 source "security/apparmor/Kconfig"
 238 source "security/loadpin/Kconfig"
 239 source "security/yama/Kconfig"
 240 source "security/safesetid/Kconfig"
 241 source "security/lockdown/Kconfig"
 242 source "security/landlock/Kconfig"
 243
 244 source "security/integrity/Kconfig"
 245
 246 choice
 247         prompt "First legacy 'major LSM' to be initialized"
 248         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 249         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 250         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 251         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 252         default DEFAULT_SECURITY_DAC
 253
 254         help
 255           This choice is there only for converting CONFIG_DEFAULT_SECURITY
 256           in old kernel configs to CONFIG_LSM in new kernel configs. Don't
 257           change this choice unless you are creating a fresh kernel config,
 258           for this choice will be ignored after CONFIG_LSM has been set.
 259
 260           Selects the legacy "major security module" that will be
 261           initialized first. Overridden by non-default CONFIG_LSM.
 262
 263         config DEFAULT_SECURITY_SELINUX
 264                 bool "SELinux" if SECURITY_SELINUX=y
 265
 266         config DEFAULT_SECURITY_SMACK
 267                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 268
 269         config DEFAULT_SECURITY_TOMOYO
 270                 bool "TOMOYO" if SECURITY_TOMOYO=y
 271
 272         config DEFAULT_SECURITY_APPARMOR
 273                 bool "AppArmor" if SECURITY_APPARMOR=y
 274
 275         config DEFAULT_SECURITY_DAC
 276                 bool "Unix Discretionary Access Controls"
 277
 278 endchoice
 279
 280 config LSM
 281         string "Ordered list of enabled LSMs"
 282         default "landlock,lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
 283         default "landlock,lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
 284         default "landlock,lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
 285         default "landlock,lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
 286         default "landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
 287         help
 288           A comma-separated list of LSMs, in initialization order.
 289           Any LSMs left off this list will be ignored. This can be
 290           controlled at boot with the "lsm=" parameter.
 291
 292           If unsure, leave this as the default.
 293
 294 source "security/Kconfig.hardening"
 295
 296 endmenu
 297