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![Linus Torvalds](/assets/img/avatar_default.png)
cache objects. This is good, but still leaves a lot of kernel memory available to be copied to/from userspace in the face of bugs. To further restrict what memory is available for copying, this creates a way to whitelist specific areas of a given slab cache object for copying to/from userspace, allowing much finer granularity of access control. Slab caches that are never exposed to userspace can declare no whitelist for their objects, thereby keeping them unavailable to userspace via dynamic copy operations. (Note, an implicit form of whitelisting is the use of constant sizes in usercopy operations and get_user()/put_user(); these bypass all hardened usercopy checks since these sizes cannot change at runtime.) This new check is WARN-by-default, so any mistakes can be found over the next several releases without breaking anyone's system. The series has roughly the following sections: - remove %p and improve reporting with offset - prepare infrastructure and whitelist kmalloc - update VFS subsystem with whitelists - update SCSI subsystem with whitelists - update network subsystem with whitelists - update process memory with whitelists - update per-architecture thread_struct with whitelists - update KVM with whitelists and fix ioctl bug - mark all other allocations as not whitelisted - update lkdtm for more sensible test overage -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Kees Cook <kees@outflux.net> iQIcBAABCgAGBQJabvleAAoJEIly9N/cbcAmO1kQAJnjVPutnLSbnUteZxtsv7W4 43Cggvokfxr6l08Yh3hUowNxZVKjhF9uwMVgRRg9Nl5WdYCN+vCQbHz+ZdzGJXKq cGqdKWgexMKX+aBdNDrK7BphUeD46sH7JWR+a/lDV/BgPxBCm9i5ZZCgXbPP89AZ NpLBji7gz49wMsnm/x135xtNlZ3dG0oKETzi7MiR+NtKtUGvoIszSKy5JdPZ4m8q 9fnXmHqmwM6uQFuzDJPt1o+D1fusTuYnjI7EgyrJRRhQ+BB3qEFZApXnKNDRS9Dm uB7jtcwefJCjlZVCf2+PWTOEifH2WFZXLPFlC8f44jK6iRW2Nc+wVRisJ3vSNBG1 gaRUe/FSge68eyfQj5OFiwM/2099MNkKdZ0fSOjEBeubQpiFChjgWgcOXa5Bhlrr C4CIhFV2qg/tOuHDAF+Q5S96oZkaTy5qcEEwhBSW15ySDUaRWFSrtboNt6ZVOhug d8JJvDCQWoNu1IQozcbv6xW/Rk7miy8c0INZ4q33YUvIZpH862+vgDWfTJ73Zy9H jR/8eG6t3kFHKS1vWdKZzOX1bEcnd02CGElFnFYUEewKoV7ZeeLsYX7zodyUAKyi Yp5CImsDbWWTsptBg6h9nt2TseXTxYCt2bbmpJcqzsqSCUwOQNQ4/YpuzLeG0ihc JgOmUnQNJWCTwUUw5AS1 =tzmJ -----END PGP SIGNATURE----- Merge tag 'usercopy-v4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull hardened usercopy whitelisting from Kees Cook: "Currently, hardened usercopy performs dynamic bounds checking on slab cache objects. This is good, but still leaves a lot of kernel memory available to be copied to/from userspace in the face of bugs. To further restrict what memory is available for copying, this creates a way to whitelist specific areas of a given slab cache object for copying to/from userspace, allowing much finer granularity of access control. Slab caches that are never exposed to userspace can declare no whitelist for their objects, thereby keeping them unavailable to userspace via dynamic copy operations. (Note, an implicit form of whitelisting is the use of constant sizes in usercopy operations and get_user()/put_user(); these bypass all hardened usercopy checks since these sizes cannot change at runtime.) This new check is WARN-by-default, so any mistakes can be found over the next several releases without breaking anyone's system. The series has roughly the following sections: - remove %p and improve reporting with offset - prepare infrastructure and whitelist kmalloc - update VFS subsystem with whitelists - update SCSI subsystem with whitelists - update network subsystem with whitelists - update process memory with whitelists - update per-architecture thread_struct with whitelists - update KVM with whitelists and fix ioctl bug - mark all other allocations as not whitelisted - update lkdtm for more sensible test overage" * tag 'usercopy-v4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (38 commits) lkdtm: Update usercopy tests for whitelisting usercopy: Restrict non-usercopy caches to size 0 kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl kvm: whitelist struct kvm_vcpu_arch arm: Implement thread_struct whitelist for hardened usercopy arm64: Implement thread_struct whitelist for hardened usercopy x86: Implement thread_struct whitelist for hardened usercopy fork: Provide usercopy whitelisting for task_struct fork: Define usercopy region in thread_stack slab caches fork: Define usercopy region in mm_struct slab caches net: Restrict unwhitelisted proto caches to size 0 sctp: Copy struct sctp_sock.autoclose to userspace using put_user() sctp: Define usercopy region in SCTP proto slab cache caif: Define usercopy region in caif proto slab cache ip: Define usercopy region in IP proto slab cache net: Define usercopy region in struct proto slab cache scsi: Define usercopy region in scsi_sense_cache slab cache cifs: Define usercopy region in cifs_request slab cache vxfs: Define usercopy region in vxfs_inode slab cache ufs: Define usercopy region in ufs_inode_cache slab cache ...
281 lines
9.8 KiB
Text
281 lines
9.8 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 PAGE_TABLE_ISOLATION
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bool "Remove the kernel mapping in user mode"
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default y
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depends on X86_64 && !UML
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help
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This feature reduces the number of hardware side channels by
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ensuring that the majority of kernel addresses are not mapped
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into userspace.
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See Documentation/x86/pti.txt for more details.
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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_FALLBACK
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bool "Allow usercopy whitelist violations to fallback to object size"
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depends on HARDENED_USERCOPY
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default y
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help
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This is a temporary option that allows missing usercopy whitelists
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to be discovered via a WARN() to the kernel log, instead of
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rejecting the copy, falling back to non-whitelisted hardened
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usercopy that checks the slab allocation size instead of the
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whitelist size. This option will be removed once it seems like
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all missing usercopy whitelists have been identified and fixed.
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Booting with "slab_common.usercopy_fallback=Y/N" can change
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this setting.
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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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