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_LSM_DEBUG
  49         bool "Enable debugging of the LSM infrastructure"
  50         depends on SECURITY
  51         help
  52           This allows you to choose debug messages related to
  53           security modules configured into your kernel. These
  54           messages may be helpful in determining how a security
  55           module is using security blobs.
  56
  57           If you are unsure how to answer this question, answer N.
  58
  59 config SECURITYFS
  60         bool "Enable the securityfs filesystem"
  61         help
  62           This will build the securityfs filesystem.  It is currently used by
  63           the TPM bios character driver and IMA, an integrity provider.  It is
  64           not used by SELinux or SMACK.
  65
  66           If you are unsure how to answer this question, answer N.
  67
  68 config SECURITY_NETWORK
  69         bool "Socket and Networking Security Hooks"
  70         depends on SECURITY
  71         help
  72           This enables the socket and networking security hooks.
  73           If enabled, a security module can use these hooks to
  74           implement socket and networking access controls.
  75           If you are unsure how to answer this question, answer N.
  76
  77 config PAGE_TABLE_ISOLATION
  78         bool "Remove the kernel mapping in user mode"
  79         default y
  80         depends on X86_64 && !UML
  81         help
  82           This feature reduces the number of hardware side channels by
  83           ensuring that the majority of kernel addresses are not mapped
  84           into userspace.
  85
  86           See Documentation/x86/pti.txt for more details.
  87
  88 config SECURITY_INFINIBAND
  89         bool "Infiniband Security Hooks"
  90         depends on SECURITY && INFINIBAND
  91         help
  92           This enables the Infiniband security hooks.
  93           If enabled, a security module can use these hooks to
  94           implement Infiniband access controls.
  95           If you are unsure how to answer this question, answer N.
  96
  97 config SECURITY_NETWORK_XFRM
  98         bool "XFRM (IPSec) Networking Security Hooks"
  99         depends on XFRM && SECURITY_NETWORK
 100         help
 101           This enables the XFRM (IPSec) networking security hooks.
 102           If enabled, a security module can use these hooks to
 103           implement per-packet access controls based on labels
 104           derived from IPSec policy.  Non-IPSec communications are
 105           designated as unlabelled, and only sockets authorized
 106           to communicate unlabelled data can send without using
 107           IPSec.
 108           If you are unsure how to answer this question, answer N.
 109
 110 config SECURITY_PATH
 111         bool "Security hooks for pathname based access control"
 112         depends on SECURITY
 113         help
 114           This enables the security hooks for pathname based access control.
 115           If enabled, a security module can use these hooks to
 116           implement pathname based access controls.
 117           If you are unsure how to answer this question, answer N.
 118
 119 config INTEL_TXT
 120         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
 121         depends on HAVE_INTEL_TXT
 122         help
 123           This option enables support for booting the kernel with the
 124           Trusted Boot (tboot) module. This will utilize
 125           Intel(R) Trusted Execution Technology to perform a measured launch
 126           of the kernel. If the system does not support Intel(R) TXT, this
 127           will have no effect.
 128
 129           Intel TXT will provide higher assurance of system configuration and
 130           initial state as well as data reset protection.  This is used to
 131           create a robust initial kernel measurement and verification, which
 132           helps to ensure that kernel security mechanisms are functioning
 133           correctly. This level of protection requires a root of trust outside
 134           of the kernel itself.
 135
 136           Intel TXT also helps solve real end user concerns about having
 137           confidence that their hardware is running the VMM or kernel that
 138           it was configured with, especially since they may be responsible for
 139           providing such assurances to VMs and services running on it.
 140
 141           See <http://www.intel.com/technology/security/> for more information
 142           about Intel(R) TXT.
 143           See <http://tboot.sourceforge.net> for more information about tboot.
 144           See Documentation/intel_txt.txt for a description of how to enable
 145           Intel TXT support in a kernel boot.
 146
 147           If you are unsure as to whether this is required, answer N.
 148
 149 config LSM_MMAP_MIN_ADDR
 150         int "Low address space for LSM to protect from user allocation"
 151         depends on SECURITY && SECURITY_SELINUX
 152         default 32768 if ARM || (ARM64 && COMPAT)
 153         default 65536
 154         help
 155           This is the portion of low virtual memory which should be protected
 156           from userspace allocation.  Keeping a user from writing to low pages
 157           can help reduce the impact of kernel NULL pointer bugs.
 158
 159           For most ia64, ppc64 and x86 users with lots of address space
 160           a value of 65536 is reasonable and should cause no problems.
 161           On arm and other archs it should not be higher than 32768.
 162           Programs which use vm86 functionality or have some need to map
 163           this low address space will need the permission specific to the
 164           systems running LSM.
 165
 166 config HAVE_HARDENED_USERCOPY_ALLOCATOR
 167         bool
 168         help
 169           The heap allocator implements __check_heap_object() for
 170           validating memory ranges against heap object sizes in
 171           support of CONFIG_HARDENED_USERCOPY.
 172
 173 config HARDENED_USERCOPY
 174         bool "Harden memory copies between kernel and userspace"
 175         depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 176         select BUG
 177         imply STRICT_DEVMEM
 178         help
 179           This option checks for obviously wrong memory regions when
 180           copying memory to/from the kernel (via copy_to_user() and
 181           copy_from_user() functions) by rejecting memory ranges that
 182           are larger than the specified heap object, span multiple
 183           separately allocated pages, are not on the process stack,
 184           or are part of the kernel text. This kills entire classes
 185           of heap overflow exploits and similar kernel memory exposures.
 186
 187 config HARDENED_USERCOPY_PAGESPAN
 188         bool "Refuse to copy allocations that span multiple pages"
 189         depends on HARDENED_USERCOPY
 190         depends on EXPERT
 191         help
 192           When a multi-page allocation is done without __GFP_COMP,
 193           hardened usercopy will reject attempts to copy it. There are,
 194           however, several cases of this in the kernel that have not all
 195           been removed. This config is intended to be used only while
 196           trying to find such users.
 197
 198 config FORTIFY_SOURCE
 199         bool "Harden common str/mem functions against buffer overflows"
 200         depends on ARCH_HAS_FORTIFY_SOURCE
 201         help
 202           Detect overflows of buffers in common string and memory functions
 203           where the compiler can determine and validate the buffer sizes.
 204
 205 config STATIC_USERMODEHELPER
 206         bool "Force all usermode helper calls through a single binary"
 207         help
 208           By default, the kernel can call many different userspace
 209           binary programs through the "usermode helper" kernel
 210           interface.  Some of these binaries are statically defined
 211           either in the kernel code itself, or as a kernel configuration
 212           option.  However, some of these are dynamically created at
 213           runtime, or can be modified after the kernel has started up.
 214           To provide an additional layer of security, route all of these
 215           calls through a single executable that can not have its name
 216           changed.
 217
 218           Note, it is up to this single binary to then call the relevant
 219           "real" usermode helper binary, based on the first argument
 220           passed to it.  If desired, this program can filter and pick
 221           and choose what real programs are called.
 222
 223           If you wish for all usermode helper programs are to be
 224           disabled, choose this option and then set
 225           STATIC_USERMODEHELPER_PATH to an empty string.
 226
 227 config STATIC_USERMODEHELPER_PATH
 228         string "Path to the static usermode helper binary"
 229         depends on STATIC_USERMODEHELPER
 230         default "/sbin/usermode-helper"
 231         help
 232           The binary called by the kernel when any usermode helper
 233           program is wish to be run.  The "real" application's name will
 234           be in the first argument passed to this program on the command
 235           line.
 236
 237           If you wish for all usermode helper programs to be disabled,
 238           specify an empty string here (i.e. "").
 239
 240 config LOCK_DOWN_KERNEL
 241         bool "Allow the kernel to be 'locked down'"
 242         help
 243           Allow the kernel to be locked down under certain circumstances, for
 244           instance if UEFI secure boot is enabled.  Locking down the kernel
 245           turns off various features that might otherwise allow access to the
 246           kernel image (eg. setting MSR registers).
 247
 248 config ALLOW_LOCKDOWN_LIFT_BY_SYSRQ
 249         bool "Allow the kernel lockdown to be lifted by SysRq"
 250         depends on LOCK_DOWN_KERNEL && MAGIC_SYSRQ
 251         help
 252           Allow the lockdown on a kernel to be lifted, by pressing a SysRq key
 253           combination on a wired keyboard.
 254
 255 config LOCK_DOWN_IN_EFI_SECURE_BOOT
 256         bool "Lock down the kernel in EFI Secure Boot mode"
 257         default n
 258         select LOCK_DOWN_KERNEL
 259         depends on EFI
 260         help
 261           UEFI Secure Boot provides a mechanism for ensuring that the firmware
 262           will only load signed bootloaders and kernels.  Secure boot mode may
 263           be determined from EFI variables provided by the system firmware if
 264           not indicated by the boot parameters.
 265
 266           Enabling this option turns on results in kernel lockdown being
 267           triggered if EFI Secure Boot is set.
 268
 269
 270 source security/selinux/Kconfig
 271 source security/smack/Kconfig
 272 source security/tomoyo/Kconfig
 273 source security/apparmor/Kconfig
 274 source security/loadpin/Kconfig
 275 source security/yama/Kconfig
 276
 277 source security/integrity/Kconfig
 278
 279 choice
 280         prompt "Default security module"
 281         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 282         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 283         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 284         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 285         default DEFAULT_SECURITY_DAC
 286
 287         help
 288           Select the security module that will be used by default if the
 289           kernel parameter security= is not specified.
 290
 291         config DEFAULT_SECURITY_SELINUX
 292                 bool "SELinux" if SECURITY_SELINUX=y
 293
 294         config DEFAULT_SECURITY_SMACK
 295                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 296
 297         config DEFAULT_SECURITY_TOMOYO
 298                 bool "TOMOYO" if SECURITY_TOMOYO=y
 299
 300         config DEFAULT_SECURITY_APPARMOR
 301                 bool "AppArmor" if SECURITY_APPARMOR=y
 302
 303         config DEFAULT_SECURITY_DAC
 304                 bool "Unix Discretionary Access Controls"
 305
 306 endchoice
 307
 308 config DEFAULT_SECURITY
 309         string
 310         default "selinux" if DEFAULT_SECURITY_SELINUX
 311         default "smack" if DEFAULT_SECURITY_SMACK
 312         default "tomoyo" if DEFAULT_SECURITY_TOMOYO
 313         default "apparmor" if DEFAULT_SECURITY_APPARMOR
 314         default "" if DEFAULT_SECURITY_DAC
 315
 316 endmenu
 317