22ec1a2aea
As done for /proc/kcore in commitdf04abfd18("fs/proc/kcore.c: Add bounce buffer for ktext data") this adds a bounce buffer when reading memory via /dev/mem. This is needed to allow kernel text memory to be read out when built with CONFIG_HARDENED_USERCOPY (which refuses to read out kernel text) and without CONFIG_STRICT_DEVMEM (which would have refused to read any RAM contents at all). Since this build configuration isn't common (most systems with CONFIG_HARDENED_USERCOPY also have CONFIG_STRICT_DEVMEM), this also tries to inform Kconfig about the recommended settings. This patch is modified from Brad Spengler/PaX Team's changes to /dev/mem code in the last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Fixes:f5509cc18d("mm: Hardened usercopy") Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
256 lines
8.9 KiB
Text
256 lines
8.9 KiB
Text
#
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# Security configuration
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#
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menu "Security options"
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source security/keys/Kconfig
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config SECURITY_DMESG_RESTRICT
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bool "Restrict unprivileged access to the kernel syslog"
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default n
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help
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This enforces restrictions on unprivileged users reading the kernel
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syslog via dmesg(8).
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If this option is not selected, no restrictions will be enforced
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unless the dmesg_restrict sysctl is explicitly set to (1).
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If you are unsure how to answer this question, answer N.
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config SECURITY
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bool "Enable different security models"
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depends on SYSFS
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depends on MULTIUSER
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help
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This allows you to choose different security modules to be
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configured into your kernel.
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If this option is not selected, the default Linux security
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model will be used.
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If you are unsure how to answer this question, answer N.
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config SECURITY_WRITABLE_HOOKS
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depends on SECURITY
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bool
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default n
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config SECURITYFS
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bool "Enable the securityfs filesystem"
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help
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This will build the securityfs filesystem. It is currently used by
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the TPM bios character driver and IMA, an integrity provider. It is
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not used by SELinux or SMACK.
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If you are unsure how to answer this question, answer N.
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config SECURITY_NETWORK
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bool "Socket and Networking Security Hooks"
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depends on SECURITY
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help
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This enables the socket and networking security hooks.
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If enabled, a security module can use these hooks to
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implement socket and networking access controls.
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If you are unsure how to answer this question, answer N.
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config SECURITY_INFINIBAND
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bool "Infiniband Security Hooks"
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depends on SECURITY && INFINIBAND
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help
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This enables the Infiniband security hooks.
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If enabled, a security module can use these hooks to
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implement Infiniband access controls.
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If you are unsure how to answer this question, answer N.
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config SECURITY_NETWORK_XFRM
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bool "XFRM (IPSec) Networking Security Hooks"
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depends on XFRM && SECURITY_NETWORK
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help
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This enables the XFRM (IPSec) networking security hooks.
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If enabled, a security module can use these hooks to
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implement per-packet access controls based on labels
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derived from IPSec policy. Non-IPSec communications are
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designated as unlabelled, and only sockets authorized
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to communicate unlabelled data can send without using
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IPSec.
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If you are unsure how to answer this question, answer N.
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config SECURITY_PATH
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bool "Security hooks for pathname based access control"
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depends on SECURITY
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help
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This enables the security hooks for pathname based access control.
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If enabled, a security module can use these hooks to
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implement pathname based access controls.
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If you are unsure how to answer this question, answer N.
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config INTEL_TXT
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bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
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depends on HAVE_INTEL_TXT
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help
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This option enables support for booting the kernel with the
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Trusted Boot (tboot) module. This will utilize
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Intel(R) Trusted Execution Technology to perform a measured launch
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of the kernel. If the system does not support Intel(R) TXT, this
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will have no effect.
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Intel TXT will provide higher assurance of system configuration and
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initial state as well as data reset protection. This is used to
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create a robust initial kernel measurement and verification, which
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helps to ensure that kernel security mechanisms are functioning
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correctly. This level of protection requires a root of trust outside
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of the kernel itself.
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Intel TXT also helps solve real end user concerns about having
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confidence that their hardware is running the VMM or kernel that
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it was configured with, especially since they may be responsible for
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providing such assurances to VMs and services running on it.
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See <http://www.intel.com/technology/security/> for more information
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about Intel(R) TXT.
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See <http://tboot.sourceforge.net> for more information about tboot.
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See Documentation/intel_txt.txt for a description of how to enable
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Intel TXT support in a kernel boot.
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If you are unsure as to whether this is required, answer N.
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config LSM_MMAP_MIN_ADDR
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int "Low address space for LSM to protect from user allocation"
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depends on SECURITY && SECURITY_SELINUX
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default 32768 if ARM || (ARM64 && COMPAT)
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default 65536
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help
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This is the portion of low virtual memory which should be protected
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from userspace allocation. Keeping a user from writing to low pages
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can help reduce the impact of kernel NULL pointer bugs.
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For most ia64, ppc64 and x86 users with lots of address space
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a value of 65536 is reasonable and should cause no problems.
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On arm and other archs it should not be higher than 32768.
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Programs which use vm86 functionality or have some need to map
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this low address space will need the permission specific to the
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systems running LSM.
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config HAVE_HARDENED_USERCOPY_ALLOCATOR
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bool
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help
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The heap allocator implements __check_heap_object() for
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validating memory ranges against heap object sizes in
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support of CONFIG_HARDENED_USERCOPY.
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config HARDENED_USERCOPY
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bool "Harden memory copies between kernel and userspace"
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depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
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select BUG
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imply STRICT_DEVMEM
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help
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This option checks for obviously wrong memory regions when
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copying memory to/from the kernel (via copy_to_user() and
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copy_from_user() functions) by rejecting memory ranges that
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are larger than the specified heap object, span multiple
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separately allocated pages, are not on the process stack,
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or are part of the kernel text. This kills entire classes
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of heap overflow exploits and similar kernel memory exposures.
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config HARDENED_USERCOPY_PAGESPAN
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bool "Refuse to copy allocations that span multiple pages"
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depends on HARDENED_USERCOPY
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depends on EXPERT
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help
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When a multi-page allocation is done without __GFP_COMP,
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hardened usercopy will reject attempts to copy it. There are,
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however, several cases of this in the kernel that have not all
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been removed. This config is intended to be used only while
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trying to find such users.
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config FORTIFY_SOURCE
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bool "Harden common str/mem functions against buffer overflows"
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depends on ARCH_HAS_FORTIFY_SOURCE
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help
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Detect overflows of buffers in common string and memory functions
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where the compiler can determine and validate the buffer sizes.
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config STATIC_USERMODEHELPER
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bool "Force all usermode helper calls through a single binary"
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help
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By default, the kernel can call many different userspace
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binary programs through the "usermode helper" kernel
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interface. Some of these binaries are statically defined
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either in the kernel code itself, or as a kernel configuration
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option. However, some of these are dynamically created at
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runtime, or can be modified after the kernel has started up.
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To provide an additional layer of security, route all of these
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calls through a single executable that can not have its name
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changed.
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Note, it is up to this single binary to then call the relevant
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"real" usermode helper binary, based on the first argument
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passed to it. If desired, this program can filter and pick
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and choose what real programs are called.
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If you wish for all usermode helper programs are to be
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disabled, choose this option and then set
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STATIC_USERMODEHELPER_PATH to an empty string.
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config STATIC_USERMODEHELPER_PATH
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string "Path to the static usermode helper binary"
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depends on STATIC_USERMODEHELPER
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default "/sbin/usermode-helper"
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help
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The binary called by the kernel when any usermode helper
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program is wish to be run. The "real" application's name will
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be in the first argument passed to this program on the command
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line.
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If you wish for all usermode helper programs to be disabled,
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specify an empty string here (i.e. "").
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source security/selinux/Kconfig
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source security/smack/Kconfig
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source security/tomoyo/Kconfig
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source security/apparmor/Kconfig
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source security/loadpin/Kconfig
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source security/yama/Kconfig
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source security/integrity/Kconfig
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choice
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prompt "Default security module"
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default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
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default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
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default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
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default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
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default DEFAULT_SECURITY_DAC
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help
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Select the security module that will be used by default if the
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kernel parameter security= is not specified.
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config DEFAULT_SECURITY_SELINUX
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bool "SELinux" if SECURITY_SELINUX=y
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config DEFAULT_SECURITY_SMACK
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bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
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config DEFAULT_SECURITY_TOMOYO
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bool "TOMOYO" if SECURITY_TOMOYO=y
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config DEFAULT_SECURITY_APPARMOR
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bool "AppArmor" if SECURITY_APPARMOR=y
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config DEFAULT_SECURITY_DAC
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bool "Unix Discretionary Access Controls"
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endchoice
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config DEFAULT_SECURITY
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string
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default "selinux" if DEFAULT_SECURITY_SELINUX
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default "smack" if DEFAULT_SECURITY_SMACK
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default "tomoyo" if DEFAULT_SECURITY_TOMOYO
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default "apparmor" if DEFAULT_SECURITY_APPARMOR
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default "" if DEFAULT_SECURITY_DAC
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endmenu
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