security/Kconfig

   1 #
   2 # Security configuration
   3 #
   4
   5 menu "Security options"
   6
   7 source security/keys/Kconfig
   8
   9 config SECURITY_DMESG_RESTRICT
  10         bool "Restrict unprivileged access to the kernel syslog"
  11         default n
  12         help
  13           This enforces restrictions on unprivileged users reading the kernel
  14           syslog via dmesg(8).
  15
  16           If this option is not selected, no restrictions will be enforced
  17           unless the dmesg_restrict sysctl is explicitly set to (1).
  18
  19           If you are unsure how to answer this question, answer N.
  20
  21 config SECURITY_PERF_EVENTS_RESTRICT
  22         bool "Restrict unprivileged use of performance events"
  23         depends on PERF_EVENTS
  24         help
  25           If you say Y here, the kernel.perf_event_paranoid sysctl
  26           will be set to 3 by default, and no unprivileged use of the
  27           perf_event_open syscall will be permitted unless it is
  28           changed.
  29
  30 config SECURITY
  31         bool "Enable different security models"
  32         depends on SYSFS
  33         depends on MULTIUSER
  34         help
  35           This allows you to choose different security modules to be
  36           configured into your kernel.
  37
  38           If this option is not selected, the default Linux security
  39           model will be used.
  40
  41           If you are unsure how to answer this question, answer N.
  42
  43 config SECURITY_WRITABLE_HOOKS
  44         depends on SECURITY
  45         bool
  46         default n
  47
  48 config SECURITY_STACKING
  49         bool "Security module stacking"
  50         depends on SECURITY
  51         help
  52           Allows multiple major security modules to be stacked.
  53           Modules are invoked in the order registered with a
  54           "bail on fail" policy, in which the infrastructure
  55           will stop processing once a denial is detected. Not
  56           all modules can be stacked. SELinux and Smack are
  57           known to be incompatible. User space components may
  58           have trouble identifying the security module providing
  59           data in some cases.
  60
  61           If you select this option you will have to select which
  62           of the stackable modules you wish to be active. The
  63           "Default security module" will be ignored. The boot line
  64           "security=" option can be used to specify that one of
  65           the modules identifed for stacking should be used instead
  66           of the entire stack.
  67
  68           If you are unsure how to answer this question, answer N.
  69
  70 config SECURITY_LSM_DEBUG
  71         bool "Enable debugging of the LSM infrastructure"
  72         depends on SECURITY
  73         help
  74           This allows you to choose debug messages related to
  75           security modules configured into your kernel. These
  76           messages may be helpful in determining how a security
  77           module is using security blobs.
  78
  79           If you are unsure how to answer this question, answer N.
  80
  81 config SECURITYFS
  82         bool "Enable the securityfs filesystem"
  83         help
  84           This will build the securityfs filesystem.  It is currently used by
  85           the TPM bios character driver and IMA, an integrity provider.  It is
  86           not used by SELinux or SMACK.
  87
  88           If you are unsure how to answer this question, answer N.
  89
  90 config SECURITY_NETWORK
  91         bool "Socket and Networking Security Hooks"
  92         depends on SECURITY
  93         help
  94           This enables the socket and networking security hooks.
  95           If enabled, a security module can use these hooks to
  96           implement socket and networking access controls.
  97           If you are unsure how to answer this question, answer N.
  98
  99 config SECURITY_INFINIBAND
 100         bool "Infiniband Security Hooks"
 101         depends on SECURITY && INFINIBAND
 102         help
 103           This enables the Infiniband security hooks.
 104           If enabled, a security module can use these hooks to
 105           implement Infiniband access controls.
 106           If you are unsure how to answer this question, answer N.
 107
 108 config SECURITY_NETWORK_XFRM
 109         bool "XFRM (IPSec) Networking Security Hooks"
 110         depends on XFRM && SECURITY_NETWORK
 111         help
 112           This enables the XFRM (IPSec) networking security hooks.
 113           If enabled, a security module can use these hooks to
 114           implement per-packet access controls based on labels
 115           derived from IPSec policy.  Non-IPSec communications are
 116           designated as unlabelled, and only sockets authorized
 117           to communicate unlabelled data can send without using
 118           IPSec.
 119           If you are unsure how to answer this question, answer N.
 120
 121 config SECURITY_PATH
 122         bool "Security hooks for pathname based access control"
 123         depends on SECURITY
 124         help
 125           This enables the security hooks for pathname based access control.
 126           If enabled, a security module can use these hooks to
 127           implement pathname based access controls.
 128           If you are unsure how to answer this question, answer N.
 129
 130 config INTEL_TXT
 131         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
 132         depends on HAVE_INTEL_TXT
 133         help
 134           This option enables support for booting the kernel with the
 135           Trusted Boot (tboot) module. This will utilize
 136           Intel(R) Trusted Execution Technology to perform a measured launch
 137           of the kernel. If the system does not support Intel(R) TXT, this
 138           will have no effect.
 139
 140           Intel TXT will provide higher assurance of system configuration and
 141           initial state as well as data reset protection.  This is used to
 142           create a robust initial kernel measurement and verification, which
 143           helps to ensure that kernel security mechanisms are functioning
 144           correctly. This level of protection requires a root of trust outside
 145           of the kernel itself.
 146
 147           Intel TXT also helps solve real end user concerns about having
 148           confidence that their hardware is running the VMM or kernel that
 149           it was configured with, especially since they may be responsible for
 150           providing such assurances to VMs and services running on it.
 151
 152           See <http://www.intel.com/technology/security/> for more information
 153           about Intel(R) TXT.
 154           See <http://tboot.sourceforge.net> for more information about tboot.
 155           See Documentation/intel_txt.txt for a description of how to enable
 156           Intel TXT support in a kernel boot.
 157
 158           If you are unsure as to whether this is required, answer N.
 159
 160 config LSM_MMAP_MIN_ADDR
 161         int "Low address space for LSM to protect from user allocation"
 162         depends on SECURITY && SECURITY_SELINUX
 163         default 32768 if ARM || (ARM64 && COMPAT)
 164         default 65536
 165         help
 166           This is the portion of low virtual memory which should be protected
 167           from userspace allocation.  Keeping a user from writing to low pages
 168           can help reduce the impact of kernel NULL pointer bugs.
 169
 170           For most ia64, ppc64 and x86 users with lots of address space
 171           a value of 65536 is reasonable and should cause no problems.
 172           On arm and other archs it should not be higher than 32768.
 173           Programs which use vm86 functionality or have some need to map
 174           this low address space will need the permission specific to the
 175           systems running LSM.
 176
 177 config HAVE_HARDENED_USERCOPY_ALLOCATOR
 178         bool
 179         help
 180           The heap allocator implements __check_heap_object() for
 181           validating memory ranges against heap object sizes in
 182           support of CONFIG_HARDENED_USERCOPY.
 183
 184 config HARDENED_USERCOPY
 185         bool "Harden memory copies between kernel and userspace"
 186         depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 187         select BUG
 188         help
 189           This option checks for obviously wrong memory regions when
 190           copying memory to/from the kernel (via copy_to_user() and
 191           copy_from_user() functions) by rejecting memory ranges that
 192           are larger than the specified heap object, span multiple
 193           separately allocated pages, are not on the process stack,
 194           or are part of the kernel text. This kills entire classes
 195           of heap overflow exploits and similar kernel memory exposures.
 196
 197 config HARDENED_USERCOPY_PAGESPAN
 198         bool "Refuse to copy allocations that span multiple pages"
 199         depends on HARDENED_USERCOPY
 200         depends on EXPERT
 201         help
 202           When a multi-page allocation is done without __GFP_COMP,
 203           hardened usercopy will reject attempts to copy it. There are,
 204           however, several cases of this in the kernel that have not all
 205           been removed. This config is intended to be used only while
 206           trying to find such users.
 207
 208 config FORTIFY_SOURCE
 209         bool "Harden common str/mem functions against buffer overflows"
 210         depends on ARCH_HAS_FORTIFY_SOURCE
 211         help
 212           Detect overflows of buffers in common string and memory functions
 213           where the compiler can determine and validate the buffer sizes.
 214
 215 config STATIC_USERMODEHELPER
 216         bool "Force all usermode helper calls through a single binary"
 217         help
 218           By default, the kernel can call many different userspace
 219           binary programs through the "usermode helper" kernel
 220           interface.  Some of these binaries are statically defined
 221           either in the kernel code itself, or as a kernel configuration
 222           option.  However, some of these are dynamically created at
 223           runtime, or can be modified after the kernel has started up.
 224           To provide an additional layer of security, route all of these
 225           calls through a single executable that can not have its name
 226           changed.
 227
 228           Note, it is up to this single binary to then call the relevant
 229           "real" usermode helper binary, based on the first argument
 230           passed to it.  If desired, this program can filter and pick
 231           and choose what real programs are called.
 232
 233           If you wish for all usermode helper programs are to be
 234           disabled, choose this option and then set
 235           STATIC_USERMODEHELPER_PATH to an empty string.
 236
 237 config STATIC_USERMODEHELPER_PATH
 238         string "Path to the static usermode helper binary"
 239         depends on STATIC_USERMODEHELPER
 240         default "/sbin/usermode-helper"
 241         help
 242           The binary called by the kernel when any usermode helper
 243           program is wish to be run.  The "real" application's name will
 244           be in the first argument passed to this program on the command
 245           line.
 246
 247           If you wish for all usermode helper programs to be disabled,
 248           specify an empty string here (i.e. "").
 249
 250 config LOCK_DOWN_KERNEL
 251         bool "Allow the kernel to be 'locked down'"
 252         help
 253           Allow the kernel to be locked down under certain circumstances, for
 254           instance if UEFI secure boot is enabled.  Locking down the kernel
 255           turns off various features that might otherwise allow access to the
 256           kernel image (eg. setting MSR registers).
 257
 258 config ALLOW_LOCKDOWN_LIFT
 259         bool
 260         help
 261           Allow the lockdown on a kernel to be lifted, thereby restoring the
 262           ability of userspace to access the kernel image (eg. by SysRq+x under
 263           x86).
 264
 265 source security/selinux/Kconfig
 266 source security/smack/Kconfig
 267 source security/tomoyo/Kconfig
 268 source security/apparmor/Kconfig
 269 source security/loadpin/Kconfig
 270 source security/yama/Kconfig
 271
 272 source security/integrity/Kconfig
 273
 274 menu "Security Module Selection"
 275         visible if !SECURITY_STACKING
 276
 277 choice
 278         prompt "Default security module"
 279         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 280         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 281         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 282         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 283         default DEFAULT_SECURITY_DAC
 284
 285         help
 286           Select the security module that will be used by default if the
 287           kernel parameter security= is not specified.
 288
 289         config DEFAULT_SECURITY_SELINUX
 290                 bool "SELinux" if SECURITY_SELINUX=y
 291
 292         config DEFAULT_SECURITY_SMACK
 293                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 294
 295         config DEFAULT_SECURITY_TOMOYO
 296                 bool "TOMOYO" if SECURITY_TOMOYO=y
 297
 298         config DEFAULT_SECURITY_APPARMOR
 299                 bool "AppArmor" if SECURITY_APPARMOR=y
 300
 301         config DEFAULT_SECURITY_DAC
 302                 bool "Unix Discretionary Access Controls"
 303
 304 endchoice
 305
 306 config DEFAULT_SECURITY
 307         string
 308         default "selinux" if DEFAULT_SECURITY_SELINUX
 309         default "smack" if DEFAULT_SECURITY_SMACK
 310         default "tomoyo" if DEFAULT_SECURITY_TOMOYO
 311         default "apparmor" if DEFAULT_SECURITY_APPARMOR
 312         default "" if DEFAULT_SECURITY_DAC
 313
 314 endmenu
 315
 316 menu "Security Module Stack"
 317         visible if SECURITY_STACKING
 318
 319 choice
 320         prompt "Stacked 'extreme' security module"
 321         default SECURITY_SELINUX_STACKED if SECURITY_SELINUX
 322         default SECURITY_SMACK_STACKED if SECURITY_SMACK
 323
 324         help
 325           Enable an extreme security module. These modules cannot
 326           be used at the same time.
 327
 328         config SECURITY_SELINUX_STACKED
 329                 bool "SELinux" if SECURITY_SELINUX=y
 330         help
 331           Add the SELinux security module to the stack. At this
 332           time the Smack security module is incompatible with this
 333           module.
 334           Please be sure your user space code is accomodating of
 335           this security module.
 336
 337         config SECURITY_SMACK_STACKED
 338                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 339         help
 340           Add the Smack security module to the stack. At this
 341           time the SELinux security module is incompatible with this
 342           module.
 343           Please be sure your user space code is accomodating of
 344           this security module.
 345
 346         config SECURITY_NOTHING_STACKED
 347                 bool "Use no 'extreme' security module"
 348         help
 349           Add neither the SELinux security module nor the Smack security
 350           module to the stack.
 351           Please be sure your user space code does not require either of
 352           these security modules.
 353
 354 endchoice
 355
 356 config SECURITY_TOMOYO_STACKED
 357         bool "TOMOYO support is enabled by default"
 358         depends on SECURITY_TOMOYO && SECURITY_STACKING
 359         default n
 360         help
 361           This option instructs the system to use the TOMOYO checks.
 362           If not selected the module will not be invoked.
 363           Stacked security modules may interact in unexpected ways.
 364           Please be sure your user space code is accomodating of
 365           multiple security modules.
 366
 367           If you are unsure how to answer this question, answer N.
 368
 369 config SECURITY_APPARMOR_STACKED
 370         bool "AppArmor support is enabled by default"
 371         depends on SECURITY_APPARMOR && SECURITY_STACKING
 372         default n
 373         help
 374           This option instructs the system to use the AppArmor checks.
 375           If not selected the module will not be invoked.
 376           Stacked security modules may interact in unexpected ways.
 377           Please be sure your user space code is accomodating of
 378           multiple security modules.
 379
 380           If you are unsure how to answer this question, answer N.
 381
 382 endmenu
 383
 384 endmenu