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 SECURITYFS
  49         bool "Enable the securityfs filesystem"
  50         help
  51           This will build the securityfs filesystem.  It is currently used by
  52           the TPM bios character driver and IMA, an integrity provider.  It is
  53           not used by SELinux or SMACK.
  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 && !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.txt 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 <http://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/intel_txt.txt 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         select BUG
 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_PAGESPAN
 176         bool "Refuse to copy allocations that span multiple pages"
 177         depends on HARDENED_USERCOPY
 178         depends on EXPERT
 179         help
 180           When a multi-page allocation is done without __GFP_COMP,
 181           hardened usercopy will reject attempts to copy it. There are,
 182           however, several cases of this in the kernel that have not all
 183           been removed. This config is intended to be used only while
 184           trying to find such users.
 185
 186 config FORTIFY_SOURCE
 187         bool "Harden common str/mem functions against buffer overflows"
 188         depends on ARCH_HAS_FORTIFY_SOURCE
 189         help
 190           Detect overflows of buffers in common string and memory functions
 191           where the compiler can determine and validate the buffer sizes.
 192
 193 config STATIC_USERMODEHELPER
 194         bool "Force all usermode helper calls through a single binary"
 195         help
 196           By default, the kernel can call many different userspace
 197           binary programs through the "usermode helper" kernel
 198           interface.  Some of these binaries are statically defined
 199           either in the kernel code itself, or as a kernel configuration
 200           option.  However, some of these are dynamically created at
 201           runtime, or can be modified after the kernel has started up.
 202           To provide an additional layer of security, route all of these
 203           calls through a single executable that can not have its name
 204           changed.
 205
 206           Note, it is up to this single binary to then call the relevant
 207           "real" usermode helper binary, based on the first argument
 208           passed to it.  If desired, this program can filter and pick
 209           and choose what real programs are called.
 210
 211           If you wish for all usermode helper programs are to be
 212           disabled, choose this option and then set
 213           STATIC_USERMODEHELPER_PATH to an empty string.
 214
 215 config STATIC_USERMODEHELPER_PATH
 216         string "Path to the static usermode helper binary"
 217         depends on STATIC_USERMODEHELPER
 218         default "/sbin/usermode-helper"
 219         help
 220           The binary called by the kernel when any usermode helper
 221           program is wish to be run.  The "real" application's name will
 222           be in the first argument passed to this program on the command
 223           line.
 224
 225           If you wish for all usermode helper programs to be disabled,
 226           specify an empty string here (i.e. "").
 227
 228 config LOCK_DOWN_KERNEL
 229         bool "Allow the kernel to be 'locked down'"
 230         help
 231           Allow the kernel to be locked down under certain circumstances, for
 232           instance if UEFI secure boot is enabled.  Locking down the kernel
 233           turns off various features that might otherwise allow access to the
 234           kernel image (eg. setting MSR registers).
 235
 236 config ALLOW_LOCKDOWN_LIFT_BY_SYSRQ
 237         bool "Allow the kernel lockdown to be lifted by SysRq"
 238         depends on LOCK_DOWN_KERNEL && MAGIC_SYSRQ
 239         help
 240           Allow the lockdown on a kernel to be lifted, by pressing a SysRq key
 241           combination on a wired keyboard.
 242
 243 config LOCK_DOWN_IN_EFI_SECURE_BOOT
 244         bool "Lock down the kernel in EFI Secure Boot mode"
 245         default n
 246         select LOCK_DOWN_KERNEL
 247         depends on EFI
 248         help
 249           UEFI Secure Boot provides a mechanism for ensuring that the firmware
 250           will only load signed bootloaders and kernels.  Secure boot mode may
 251           be determined from EFI variables provided by the system firmware if
 252           not indicated by the boot parameters.
 253
 254           Enabling this option turns on results in kernel lockdown being
 255           triggered if EFI Secure Boot is set.
 256
 257
 258 source security/selinux/Kconfig
 259 source security/smack/Kconfig
 260 source security/tomoyo/Kconfig
 261 source security/apparmor/Kconfig
 262 source security/loadpin/Kconfig
 263 source security/yama/Kconfig
 264
 265 source security/integrity/Kconfig
 266
 267 choice
 268         prompt "Default security module"
 269         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 270         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 271         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 272         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 273         default DEFAULT_SECURITY_DAC
 274
 275         help
 276           Select the security module that will be used by default if the
 277           kernel parameter security= is not specified.
 278
 279         config DEFAULT_SECURITY_SELINUX
 280                 bool "SELinux" if SECURITY_SELINUX=y
 281
 282         config DEFAULT_SECURITY_SMACK
 283                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 284
 285         config DEFAULT_SECURITY_TOMOYO
 286                 bool "TOMOYO" if SECURITY_TOMOYO=y
 287
 288         config DEFAULT_SECURITY_APPARMOR
 289                 bool "AppArmor" if SECURITY_APPARMOR=y
 290
 291         config DEFAULT_SECURITY_DAC
 292                 bool "Unix Discretionary Access Controls"
 293
 294 endchoice
 295
 296 config DEFAULT_SECURITY
 297         string
 298         default "selinux" if DEFAULT_SECURITY_SELINUX
 299         default "smack" if DEFAULT_SECURITY_SMACK
 300         default "tomoyo" if DEFAULT_SECURITY_TOMOYO
 301         default "apparmor" if DEFAULT_SECURITY_APPARMOR
 302         default "" if DEFAULT_SECURITY_DAC
 303
 304 endmenu
 305