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
  22         bool "Enable different security models"
  23         depends on SYSFS
  24         depends on MULTIUSER
  25         help
  26           This allows you to choose different security modules to be
  27           configured into your kernel.
  28
  29           If this option is not selected, the default Linux security
  30           model will be used.
  31
  32           If you are unsure how to answer this question, answer N.
  33
  34 config SECURITY_WRITABLE_HOOKS
  35         depends on SECURITY
  36         bool
  37         default n
  38
  39 config SECURITYFS
  40         bool "Enable the securityfs filesystem"
  41         help
  42           This will build the securityfs filesystem.  It is currently used by
  43           various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
  44
  45           If you are unsure how to answer this question, answer N.
  46
  47 config SECURITY_NETWORK
  48         bool "Socket and Networking Security Hooks"
  49         depends on SECURITY
  50         help
  51           This enables the socket and networking security hooks.
  52           If enabled, a security module can use these hooks to
  53           implement socket and networking access controls.
  54           If you are unsure how to answer this question, answer N.
  55
  56 config PAGE_TABLE_ISOLATION
  57         bool "Remove the kernel mapping in user mode"
  58         default y
  59         depends on (X86_64 || X86_PAE) && !UML
  60         help
  61           This feature reduces the number of hardware side channels by
  62           ensuring that the majority of kernel addresses are not mapped
  63           into userspace.
  64
  65           See Documentation/x86/pti.txt for more details.
  66
  67 config SECURITY_INFINIBAND
  68         bool "Infiniband Security Hooks"
  69         depends on SECURITY && INFINIBAND
  70         help
  71           This enables the Infiniband security hooks.
  72           If enabled, a security module can use these hooks to
  73           implement Infiniband access controls.
  74           If you are unsure how to answer this question, answer N.
  75
  76 config SECURITY_NETWORK_XFRM
  77         bool "XFRM (IPSec) Networking Security Hooks"
  78         depends on XFRM && SECURITY_NETWORK
  79         help
  80           This enables the XFRM (IPSec) networking security hooks.
  81           If enabled, a security module can use these hooks to
  82           implement per-packet access controls based on labels
  83           derived from IPSec policy.  Non-IPSec communications are
  84           designated as unlabelled, and only sockets authorized
  85           to communicate unlabelled data can send without using
  86           IPSec.
  87           If you are unsure how to answer this question, answer N.
  88
  89 config SECURITY_PATH
  90         bool "Security hooks for pathname based access control"
  91         depends on SECURITY
  92         help
  93           This enables the security hooks for pathname based access control.
  94           If enabled, a security module can use these hooks to
  95           implement pathname based access controls.
  96           If you are unsure how to answer this question, answer N.
  97
  98 config INTEL_TXT
  99         bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
 100         depends on HAVE_INTEL_TXT
 101         help
 102           This option enables support for booting the kernel with the
 103           Trusted Boot (tboot) module. This will utilize
 104           Intel(R) Trusted Execution Technology to perform a measured launch
 105           of the kernel. If the system does not support Intel(R) TXT, this
 106           will have no effect.
 107
 108           Intel TXT will provide higher assurance of system configuration and
 109           initial state as well as data reset protection.  This is used to
 110           create a robust initial kernel measurement and verification, which
 111           helps to ensure that kernel security mechanisms are functioning
 112           correctly. This level of protection requires a root of trust outside
 113           of the kernel itself.
 114
 115           Intel TXT also helps solve real end user concerns about having
 116           confidence that their hardware is running the VMM or kernel that
 117           it was configured with, especially since they may be responsible for
 118           providing such assurances to VMs and services running on it.
 119
 120           See <http://www.intel.com/technology/security/> for more information
 121           about Intel(R) TXT.
 122           See <http://tboot.sourceforge.net> for more information about tboot.
 123           See Documentation/intel_txt.txt for a description of how to enable
 124           Intel TXT support in a kernel boot.
 125
 126           If you are unsure as to whether this is required, answer N.
 127
 128 config LSM_MMAP_MIN_ADDR
 129         int "Low address space for LSM to protect from user allocation"
 130         depends on SECURITY && SECURITY_SELINUX
 131         default 32768 if ARM || (ARM64 && COMPAT)
 132         default 65536
 133         help
 134           This is the portion of low virtual memory which should be protected
 135           from userspace allocation.  Keeping a user from writing to low pages
 136           can help reduce the impact of kernel NULL pointer bugs.
 137
 138           For most ia64, ppc64 and x86 users with lots of address space
 139           a value of 65536 is reasonable and should cause no problems.
 140           On arm and other archs it should not be higher than 32768.
 141           Programs which use vm86 functionality or have some need to map
 142           this low address space will need the permission specific to the
 143           systems running LSM.
 144
 145 config HAVE_HARDENED_USERCOPY_ALLOCATOR
 146         bool
 147         help
 148           The heap allocator implements __check_heap_object() for
 149           validating memory ranges against heap object sizes in
 150           support of CONFIG_HARDENED_USERCOPY.
 151
 152 config HARDENED_USERCOPY
 153         bool "Harden memory copies between kernel and userspace"
 154         depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 155         imply STRICT_DEVMEM
 156         help
 157           This option checks for obviously wrong memory regions when
 158           copying memory to/from the kernel (via copy_to_user() and
 159           copy_from_user() functions) by rejecting memory ranges that
 160           are larger than the specified heap object, span multiple
 161           separately allocated pages, are not on the process stack,
 162           or are part of the kernel text. This kills entire classes
 163           of heap overflow exploits and similar kernel memory exposures.
 164
 165 config HARDENED_USERCOPY_FALLBACK
 166         bool "Allow usercopy whitelist violations to fallback to object size"
 167         depends on HARDENED_USERCOPY
 168         default y
 169         help
 170           This is a temporary option that allows missing usercopy whitelists
 171           to be discovered via a WARN() to the kernel log, instead of
 172           rejecting the copy, falling back to non-whitelisted hardened
 173           usercopy that checks the slab allocation size instead of the
 174           whitelist size. This option will be removed once it seems like
 175           all missing usercopy whitelists have been identified and fixed.
 176           Booting with "slab_common.usercopy_fallback=Y/N" can change
 177           this setting.
 178
 179 config HARDENED_USERCOPY_PAGESPAN
 180         bool "Refuse to copy allocations that span multiple pages"
 181         depends on HARDENED_USERCOPY
 182         depends on EXPERT
 183         help
 184           When a multi-page allocation is done without __GFP_COMP,
 185           hardened usercopy will reject attempts to copy it. There are,
 186           however, several cases of this in the kernel that have not all
 187           been removed. This config is intended to be used only while
 188           trying to find such users.
 189
 190 config FORTIFY_SOURCE
 191         bool "Harden common str/mem functions against buffer overflows"
 192         depends on ARCH_HAS_FORTIFY_SOURCE
 193         help
 194           Detect overflows of buffers in common string and memory functions
 195           where the compiler can determine and validate the buffer sizes.
 196
 197 config STATIC_USERMODEHELPER
 198         bool "Force all usermode helper calls through a single binary"
 199         help
 200           By default, the kernel can call many different userspace
 201           binary programs through the "usermode helper" kernel
 202           interface.  Some of these binaries are statically defined
 203           either in the kernel code itself, or as a kernel configuration
 204           option.  However, some of these are dynamically created at
 205           runtime, or can be modified after the kernel has started up.
 206           To provide an additional layer of security, route all of these
 207           calls through a single executable that can not have its name
 208           changed.
 209
 210           Note, it is up to this single binary to then call the relevant
 211           "real" usermode helper binary, based on the first argument
 212           passed to it.  If desired, this program can filter and pick
 213           and choose what real programs are called.
 214
 215           If you wish for all usermode helper programs are to be
 216           disabled, choose this option and then set
 217           STATIC_USERMODEHELPER_PATH to an empty string.
 218
 219 config STATIC_USERMODEHELPER_PATH
 220         string "Path to the static usermode helper binary"
 221         depends on STATIC_USERMODEHELPER
 222         default "/sbin/usermode-helper"
 223         help
 224           The binary called by the kernel when any usermode helper
 225           program is wish to be run.  The "real" application's name will
 226           be in the first argument passed to this program on the command
 227           line.
 228
 229           If you wish for all usermode helper programs to be disabled,
 230           specify an empty string here (i.e. "").
 231
 232 source "security/selinux/Kconfig"
 233 source "security/smack/Kconfig"
 234 source "security/tomoyo/Kconfig"
 235 source "security/apparmor/Kconfig"
 236 source "security/loadpin/Kconfig"
 237 source "security/yama/Kconfig"
 238 source "security/safesetid/Kconfig"
 239
 240 source "security/integrity/Kconfig"
 241
 242 choice
 243         prompt "First legacy 'major LSM' to be initialized"
 244         default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
 245         default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
 246         default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
 247         default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
 248         default DEFAULT_SECURITY_DAC
 249
 250         help
 251           This choice is there only for converting CONFIG_DEFAULT_SECURITY
 252           in old kernel configs to CONFIG_LSM in new kernel configs. Don't
 253           change this choice unless you are creating a fresh kernel config,
 254           for this choice will be ignored after CONFIG_LSM has been set.
 255
 256           Selects the legacy "major security module" that will be
 257           initialized first. Overridden by non-default CONFIG_LSM.
 258
 259         config DEFAULT_SECURITY_SELINUX
 260                 bool "SELinux" if SECURITY_SELINUX=y
 261
 262         config DEFAULT_SECURITY_SMACK
 263                 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
 264
 265         config DEFAULT_SECURITY_TOMOYO
 266                 bool "TOMOYO" if SECURITY_TOMOYO=y
 267
 268         config DEFAULT_SECURITY_APPARMOR
 269                 bool "AppArmor" if SECURITY_APPARMOR=y
 270
 271         config DEFAULT_SECURITY_DAC
 272                 bool "Unix Discretionary Access Controls"
 273
 274 endchoice
 275
 276 config LSM
 277         string "Ordered list of enabled LSMs"
 278         default "yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK
 279         default "yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR
 280         default "yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
 281         default "yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC
 282         default "yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
 283         help
 284           A comma-separated list of LSMs, in initialization order.
 285           Any LSMs left off this list will be ignored. This can be
 286           controlled at boot with the "lsm=" parameter.
 287
 288           If unsure, leave this as the default.
 289
 290 source "security/Kconfig.hardening"
 291
 292 endmenu
 293