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 PAGE_TABLE_ISOLATION
  67         bool "Remove the kernel mapping in user mode"
  68         default y
  69         depends on (X86_64 || X86_PAE) && !UML
  70         help
  71           This feature reduces the number of hardware side channels by
  72           ensuring that the majority of kernel addresses are not mapped
  73           into userspace.
  74
  75           See Documentation/x86/pti.rst for more details.
  76
  77 config SECURITY_INFINIBAND
  78         bool "Infiniband Security Hooks"
  79         depends on SECURITY && INFINIBAND
  80         help
  81           This enables the Infiniband security hooks.
  82           If enabled, a security module can use these hooks to
  83           implement Infiniband access controls.
  84           If you are unsure how to answer this question, answer N.
  85
  86 config SECURITY_NETWORK_XFRM
  87         bool "XFRM (IPSec) Networking Security Hooks"
  88         depends on XFRM && SECURITY_NETWORK
  89         help
  90           This enables the XFRM (IPSec) networking security hooks.
  91           If enabled, a security module can use these hooks to
  92           implement per-packet access controls based on labels
  93           derived from IPSec policy.  Non-IPSec communications are
  94           designated as unlabelled, and only sockets authorized
  95           to communicate unlabelled data can send without using
  96           IPSec.
  97           If you are unsure how to answer this question, answer N.
  98
  99 config SECURITY_PATH
 100         bool "Security hooks for pathname based access control"
 101         depends on SECURITY
 102         help
 103           This enables the security hooks for pathname based access control.
 104           If enabled, a security module can use these hooks to
 105           implement pathname based access controls.
 106           If you are unsure how to answer this question, answer N.
 107
 108 config INTEL_TXT
 109         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
 110         depends on HAVE_INTEL_TXT
 111         help
 112           This option enables support for booting the kernel with the
 113           Trusted Boot (tboot) module. This will utilize
 114           Intel(R) Trusted Execution Technology to perform a measured launch
 115           of the kernel. If the system does not support Intel(R) TXT, this
 116           will have no effect.
 117
 118           Intel TXT will provide higher assurance of system configuration and
 119           initial state as well as data reset protection.  This is used to
 120           create a robust initial kernel measurement and verification, which
 121           helps to ensure that kernel security mechanisms are functioning
 122           correctly. This level of protection requires a root of trust outside
 123           of the kernel itself.
 124
 125           Intel TXT also helps solve real end user concerns about having
 126           confidence that their hardware is running the VMM or kernel that
 127           it was configured with, especially since they may be responsible for
 128           providing such assurances to VMs and services running on it.
 129
 130           See <https://www.intel.com/technology/security/> for more information
 131           about Intel(R) TXT.
 132           See <http://tboot.sourceforge.net> for more information about tboot.
 133           See Documentation/x86/intel_txt.rst for a description of how to enable
 134           Intel TXT support in a kernel boot.
 135
 136           If you are unsure as to whether this is required, answer N.
 137
 138 config LSM_MMAP_MIN_ADDR
 139         int "Low address space for LSM to protect from user allocation"
 140         depends on SECURITY && SECURITY_SELINUX
 141         default 32768 if ARM || (ARM64 && COMPAT)
 142         default 65536
 143         help
 144           This is the portion of low virtual memory which should be protected
 145           from userspace allocation.  Keeping a user from writing to low pages
 146           can help reduce the impact of kernel NULL pointer bugs.
 147
 148           For most ia64, ppc64 and x86 users with lots of address space
 149           a value of 65536 is reasonable and should cause no problems.
 150           On arm and other archs it should not be higher than 32768.
 151           Programs which use vm86 functionality or have some need to map
 152           this low address space will need the permission specific to the
 153           systems running LSM.
 154
 155 config HAVE_HARDENED_USERCOPY_ALLOCATOR
 156         bool
 157         help
 158           The heap allocator implements __check_heap_object() for
 159           validating memory ranges against heap object sizes in
 160           support of CONFIG_HARDENED_USERCOPY.
 161
 162 config HARDENED_USERCOPY
 163         bool "Harden memory copies between kernel and userspace"
 164         depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 165         imply STRICT_DEVMEM
 166         help
 167           This option checks for obviously wrong memory regions when
 168           copying memory to/from the kernel (via copy_to_user() and
 169           copy_from_user() functions) by rejecting memory ranges that
 170           are larger than the specified heap object, span multiple
 171           separately allocated pages, are not on the process stack,
 172           or are part of the kernel text. This kills entire classes
 173           of heap overflow exploits and similar kernel memory exposures.
 174
 175 config HARDENED_USERCOPY_FALLBACK
 176         bool "Allow usercopy whitelist violations to fallback to object size"
 177         depends on HARDENED_USERCOPY
 178         default y
 179         help
 180           This is a temporary option that allows missing usercopy whitelists
 181           to be discovered via a WARN() to the kernel log, instead of
 182           rejecting the copy, falling back to non-whitelisted hardened
 183           usercopy that checks the slab allocation size instead of the
 184           whitelist size. This option will be removed once it seems like
 185           all missing usercopy whitelists have been identified and fixed.
 186           Booting with "slab_common.usercopy_fallback=Y/N" can change
 187           this setting.
 188
 189 config HARDENED_USERCOPY_PAGESPAN
 190         bool "Refuse to copy allocations that span multiple pages"
 191         depends on HARDENED_USERCOPY
 192         depends on EXPERT
 193         help
 194           When a multi-page allocation is done without __GFP_COMP,
 195           hardened usercopy will reject attempts to copy it. There are,
 196           however, several cases of this in the kernel that have not all
 197           been removed. This config is intended to be used only while
 198           trying to find such users.
 199
 200 config FORTIFY_SOURCE
 201         bool "Harden common str/mem functions against buffer overflows"
 202         depends on ARCH_HAS_FORTIFY_SOURCE
 203         # https://bugs.llvm.org/show_bug.cgi?id=50322
 204         # https://bugs.llvm.org/show_bug.cgi?id=41459
 205         depends on !CC_IS_CLANG
 206         help
 207           Detect overflows of buffers in common string and memory functions
 208           where the compiler can determine and validate the buffer sizes.
 209
 210 config STATIC_USERMODEHELPER
 211         bool "Force all usermode helper calls through a single binary"
 212         help
 213           By default, the kernel can call many different userspace
 214           binary programs through the "usermode helper" kernel
 215           interface.  Some of these binaries are statically defined
 216           either in the kernel code itself, or as a kernel configuration
 217           option.  However, some of these are dynamically created at
 218           runtime, or can be modified after the kernel has started up.
 219           To provide an additional layer of security, route all of these
 220           calls through a single executable that can not have its name
 221           changed.
 222
 223           Note, it is up to this single binary to then call the relevant
 224           "real" usermode helper binary, based on the first argument
 225           passed to it.  If desired, this program can filter and pick
 226           and choose what real programs are called.
 227
 228           If you wish for all usermode helper programs are to be
 229           disabled, choose this option and then set
 230           STATIC_USERMODEHELPER_PATH to an empty string.
 231
 232 config STATIC_USERMODEHELPER_PATH
 233         string "Path to the static usermode helper binary"
 234         depends on STATIC_USERMODEHELPER
 235         default "/sbin/usermode-helper"
 236         help
 237           The binary called by the kernel when any usermode helper
 238           program is wish to be run.  The "real" application's name will
 239           be in the first argument passed to this program on the command
 240           line.
 241
 242           If you wish for all usermode helper programs to be disabled,
 243           specify an empty string here (i.e. "").
 244
 245 source "security/selinux/Kconfig"
 246 source "security/smack/Kconfig"
 247 source "security/tomoyo/Kconfig"
 248 source "security/apparmor/Kconfig"
 249 source "security/loadpin/Kconfig"
 250 source "security/yama/Kconfig"
 251 source "security/safesetid/Kconfig"
 252 source "security/lockdown/Kconfig"
 253 source "security/landlock/Kconfig"
 254
 255 source "security/integrity/Kconfig"
 256
 257 choice
 258         prompt "First legacy 'major LSM' to be initialized"
 259         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 260         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 261         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 262         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 263         default DEFAULT_SECURITY_DAC
 264
 265         help
 266           This choice is there only for converting CONFIG_DEFAULT_SECURITY
 267           in old kernel configs to CONFIG_LSM in new kernel configs. Don't
 268           change this choice unless you are creating a fresh kernel config,
 269           for this choice will be ignored after CONFIG_LSM has been set.
 270
 271           Selects the legacy "major security module" that will be
 272           initialized first. Overridden by non-default CONFIG_LSM.
 273
 274         config DEFAULT_SECURITY_SELINUX
 275                 bool "SELinux" if SECURITY_SELINUX=y
 276
 277         config DEFAULT_SECURITY_SMACK
 278                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 279
 280         config DEFAULT_SECURITY_TOMOYO
 281                 bool "TOMOYO" if SECURITY_TOMOYO=y
 282
 283         config DEFAULT_SECURITY_APPARMOR
 284                 bool "AppArmor" if SECURITY_APPARMOR=y
 285
 286         config DEFAULT_SECURITY_DAC
 287                 bool "Unix Discretionary Access Controls"
 288
 289 endchoice
 290
 291 config LSM
 292         string "Ordered list of enabled LSMs"
 293         default "landlock,lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
 294         default "landlock,lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
 295         default "landlock,lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
 296         default "landlock,lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
 297         default "landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
 298         help
 299           A comma-separated list of LSMs, in initialization order.
 300           Any LSMs left off this list will be ignored. This can be
 301           controlled at boot with the "lsm=" parameter.
 302
 303           If unsure, leave this as the default.
 304
 305 source "security/Kconfig.hardening"
 306
 307 endmenu
 308