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52c208397c
IMA measures contents of a given file/buffer/critical-data record,
and properly re-measures it on change. However, IMA does not measure
the duplicate value for a given record, since TPM extend is a very
expensive operation. For example, if the record changes from value
'v#1' to 'v#2', and then back to 'v#1', IMA will not measure and log
the last change to 'v#1', since the hash of 'v#1' for that record is
already present in the IMA htable. This limits the ability of an
external attestation service to accurately determine the current state
of the system. The service would incorrectly conclude that the latest
value of the given record on the system is 'v#2', and act accordingly.
Define and use a new Kconfig option IMA_DISABLE_HTABLE to permit
duplicate records in the IMA measurement list.
In addition to the duplicate measurement records described above,
other duplicate file measurement records may be included in the log,
when CONFIG_IMA_DISABLE_HTABLE is enabled. For example,
- i_version is not enabled,
- i_generation changed,
- same file present on different filesystems,
- an inode is evicted from dcache
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
[zohar@linux.ibm.com: updated list of duplicate measurement records]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
344 lines
11 KiB
Plaintext
344 lines
11 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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# IBM Integrity Measurement Architecture
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#
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config IMA
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bool "Integrity Measurement Architecture(IMA)"
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select SECURITYFS
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select CRYPTO
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select CRYPTO_HMAC
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select CRYPTO_MD5
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select CRYPTO_SHA1
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select CRYPTO_HASH_INFO
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select TCG_TPM if HAS_IOMEM && !UML
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select TCG_TIS if TCG_TPM && X86
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select TCG_CRB if TCG_TPM && ACPI
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select TCG_IBMVTPM if TCG_TPM && PPC_PSERIES
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select INTEGRITY_AUDIT if AUDIT
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help
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The Trusted Computing Group(TCG) runtime Integrity
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Measurement Architecture(IMA) maintains a list of hash
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values of executables and other sensitive system files,
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as they are read or executed. If an attacker manages
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to change the contents of an important system file
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being measured, we can tell.
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If your system has a TPM chip, then IMA also maintains
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an aggregate integrity value over this list inside the
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TPM hardware, so that the TPM can prove to a third party
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whether or not critical system files have been modified.
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Read <https://www.usenix.org/events/sec04/tech/sailer.html>
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to learn more about IMA.
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If unsure, say N.
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config IMA_KEXEC
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bool "Enable carrying the IMA measurement list across a soft boot"
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depends on IMA && TCG_TPM && HAVE_IMA_KEXEC
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default n
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help
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TPM PCRs are only reset on a hard reboot. In order to validate
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a TPM's quote after a soft boot, the IMA measurement list of the
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running kernel must be saved and restored on boot.
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Depending on the IMA policy, the measurement list can grow to
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be very large.
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config IMA_MEASURE_PCR_IDX
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int
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depends on IMA
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range 8 14
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default 10
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help
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IMA_MEASURE_PCR_IDX determines the TPM PCR register index
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that IMA uses to maintain the integrity aggregate of the
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measurement list. If unsure, use the default 10.
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config IMA_LSM_RULES
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bool
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depends on IMA && AUDIT && (SECURITY_SELINUX || SECURITY_SMACK || SECURITY_APPARMOR)
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default y
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help
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Disabling this option will disregard LSM based policy rules.
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choice
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prompt "Default template"
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default IMA_NG_TEMPLATE
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depends on IMA
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help
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Select the default IMA measurement template.
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The original 'ima' measurement list template contains a
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hash, defined as 20 bytes, and a null terminated pathname,
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limited to 255 characters. The 'ima-ng' measurement list
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template permits both larger hash digests and longer
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pathnames.
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config IMA_TEMPLATE
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bool "ima"
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config IMA_NG_TEMPLATE
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bool "ima-ng (default)"
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config IMA_SIG_TEMPLATE
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bool "ima-sig"
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endchoice
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config IMA_DEFAULT_TEMPLATE
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string
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depends on IMA
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default "ima" if IMA_TEMPLATE
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default "ima-ng" if IMA_NG_TEMPLATE
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default "ima-sig" if IMA_SIG_TEMPLATE
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choice
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prompt "Default integrity hash algorithm"
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default IMA_DEFAULT_HASH_SHA1
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depends on IMA
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help
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Select the default hash algorithm used for the measurement
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list, integrity appraisal and audit log. The compiled default
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hash algorithm can be overwritten using the kernel command
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line 'ima_hash=' option.
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config IMA_DEFAULT_HASH_SHA1
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bool "SHA1 (default)"
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depends on CRYPTO_SHA1=y
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config IMA_DEFAULT_HASH_SHA256
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bool "SHA256"
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depends on CRYPTO_SHA256=y && !IMA_TEMPLATE
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config IMA_DEFAULT_HASH_SHA512
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bool "SHA512"
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depends on CRYPTO_SHA512=y && !IMA_TEMPLATE
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config IMA_DEFAULT_HASH_WP512
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bool "WP512"
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depends on CRYPTO_WP512=y && !IMA_TEMPLATE
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config IMA_DEFAULT_HASH_SM3
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bool "SM3"
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depends on CRYPTO_SM3=y && !IMA_TEMPLATE
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endchoice
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config IMA_DEFAULT_HASH
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string
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depends on IMA
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default "sha1" if IMA_DEFAULT_HASH_SHA1
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default "sha256" if IMA_DEFAULT_HASH_SHA256
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default "sha512" if IMA_DEFAULT_HASH_SHA512
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default "wp512" if IMA_DEFAULT_HASH_WP512
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default "sm3" if IMA_DEFAULT_HASH_SM3
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config IMA_WRITE_POLICY
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bool "Enable multiple writes to the IMA policy"
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depends on IMA
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default n
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help
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IMA policy can now be updated multiple times. The new rules get
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appended to the original policy. Have in mind that the rules are
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scanned in FIFO order so be careful when you design and add new ones.
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If unsure, say N.
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config IMA_READ_POLICY
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bool "Enable reading back the current IMA policy"
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depends on IMA
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default y if IMA_WRITE_POLICY
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default n if !IMA_WRITE_POLICY
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help
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It is often useful to be able to read back the IMA policy. It is
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even more important after introducing CONFIG_IMA_WRITE_POLICY.
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This option allows the root user to see the current policy rules.
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config IMA_APPRAISE
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bool "Appraise integrity measurements"
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depends on IMA
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default n
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help
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This option enables local measurement integrity appraisal.
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It requires the system to be labeled with a security extended
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attribute containing the file hash measurement. To protect
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the security extended attributes from offline attack, enable
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and configure EVM.
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For more information on integrity appraisal refer to:
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<http://linux-ima.sourceforge.net>
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If unsure, say N.
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config IMA_ARCH_POLICY
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bool "Enable loading an IMA architecture specific policy"
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depends on (KEXEC_SIG && IMA) || IMA_APPRAISE \
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&& INTEGRITY_ASYMMETRIC_KEYS
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default n
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help
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This option enables loading an IMA architecture specific policy
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based on run time secure boot flags.
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config IMA_APPRAISE_BUILD_POLICY
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bool "IMA build time configured policy rules"
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depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS
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default n
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help
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This option defines an IMA appraisal policy at build time, which
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is enforced at run time without having to specify a builtin
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policy name on the boot command line. The build time appraisal
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policy rules persist after loading a custom policy.
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Depending on the rules configured, this policy may require kernel
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modules, firmware, the kexec kernel image, and/or the IMA policy
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to be signed. Unsigned files might prevent the system from
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booting or applications from working properly.
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config IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
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bool "Appraise firmware signatures"
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depends on IMA_APPRAISE_BUILD_POLICY
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default n
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help
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This option defines a policy requiring all firmware to be signed,
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including the regulatory.db. If both this option and
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CFG80211_REQUIRE_SIGNED_REGDB are enabled, then both signature
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verification methods are necessary.
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config IMA_APPRAISE_REQUIRE_KEXEC_SIGS
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bool "Appraise kexec kernel image signatures"
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depends on IMA_APPRAISE_BUILD_POLICY
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default n
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help
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Enabling this rule will require all kexec'ed kernel images to
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be signed and verified by a public key on the trusted IMA
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keyring.
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Kernel image signatures can not be verified by the original
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kexec_load syscall. Enabling this rule will prevent its
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usage.
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config IMA_APPRAISE_REQUIRE_MODULE_SIGS
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bool "Appraise kernel modules signatures"
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depends on IMA_APPRAISE_BUILD_POLICY
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default n
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help
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Enabling this rule will require all kernel modules to be signed
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and verified by a public key on the trusted IMA keyring.
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Kernel module signatures can only be verified by IMA-appraisal,
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via the finit_module syscall. Enabling this rule will prevent
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the usage of the init_module syscall.
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config IMA_APPRAISE_REQUIRE_POLICY_SIGS
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bool "Appraise IMA policy signature"
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depends on IMA_APPRAISE_BUILD_POLICY
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default n
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help
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Enabling this rule will require the IMA policy to be signed and
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and verified by a key on the trusted IMA keyring.
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config IMA_APPRAISE_BOOTPARAM
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bool "ima_appraise boot parameter"
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depends on IMA_APPRAISE
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default y
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help
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This option enables the different "ima_appraise=" modes
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(eg. fix, log) from the boot command line.
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config IMA_APPRAISE_MODSIG
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bool "Support module-style signatures for appraisal"
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depends on IMA_APPRAISE
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depends on INTEGRITY_ASYMMETRIC_KEYS
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select PKCS7_MESSAGE_PARSER
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select MODULE_SIG_FORMAT
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default n
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help
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Adds support for signatures appended to files. The format of the
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appended signature is the same used for signed kernel modules.
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The modsig keyword can be used in the IMA policy to allow a hook
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to accept such signatures.
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config IMA_TRUSTED_KEYRING
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bool "Require all keys on the .ima keyring be signed (deprecated)"
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depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING
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depends on INTEGRITY_ASYMMETRIC_KEYS
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select INTEGRITY_TRUSTED_KEYRING
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default y
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help
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This option requires that all keys added to the .ima
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keyring be signed by a key on the system trusted keyring.
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This option is deprecated in favor of INTEGRITY_TRUSTED_KEYRING
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config IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
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bool "Permit keys validly signed by a built-in or secondary CA cert (EXPERIMENTAL)"
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depends on SYSTEM_TRUSTED_KEYRING
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depends on SECONDARY_TRUSTED_KEYRING
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depends on INTEGRITY_ASYMMETRIC_KEYS
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select INTEGRITY_TRUSTED_KEYRING
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default n
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help
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Keys may be added to the IMA or IMA blacklist keyrings, if the
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key is validly signed by a CA cert in the system built-in or
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secondary trusted keyrings.
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Intermediate keys between those the kernel has compiled in and the
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IMA keys to be added may be added to the system secondary keyring,
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provided they are validly signed by a key already resident in the
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built-in or secondary trusted keyrings.
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config IMA_BLACKLIST_KEYRING
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bool "Create IMA machine owner blacklist keyrings (EXPERIMENTAL)"
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depends on SYSTEM_TRUSTED_KEYRING
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depends on IMA_TRUSTED_KEYRING
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default n
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help
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This option creates an IMA blacklist keyring, which contains all
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revoked IMA keys. It is consulted before any other keyring. If
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the search is successful the requested operation is rejected and
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an error is returned to the caller.
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config IMA_LOAD_X509
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bool "Load X509 certificate onto the '.ima' trusted keyring"
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depends on IMA_TRUSTED_KEYRING
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default n
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help
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File signature verification is based on the public keys
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loaded on the .ima trusted keyring. These public keys are
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X509 certificates signed by a trusted key on the
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.system keyring. This option enables X509 certificate
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loading from the kernel onto the '.ima' trusted keyring.
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config IMA_X509_PATH
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string "IMA X509 certificate path"
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depends on IMA_LOAD_X509
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default "/etc/keys/x509_ima.der"
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help
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This option defines IMA X509 certificate path.
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config IMA_APPRAISE_SIGNED_INIT
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bool "Require signed user-space initialization"
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depends on IMA_LOAD_X509
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default n
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help
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This option requires user-space init to be signed.
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config IMA_MEASURE_ASYMMETRIC_KEYS
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bool
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depends on IMA
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depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE=y
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default y
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config IMA_QUEUE_EARLY_BOOT_KEYS
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bool
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depends on IMA_MEASURE_ASYMMETRIC_KEYS
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depends on SYSTEM_TRUSTED_KEYRING
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default y
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config IMA_SECURE_AND_OR_TRUSTED_BOOT
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bool
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depends on IMA_ARCH_POLICY
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help
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This option is selected by architectures to enable secure and/or
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trusted boot based on IMA runtime policies.
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config IMA_DISABLE_HTABLE
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bool "Disable htable to allow measurement of duplicate records"
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depends on IMA
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default n
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help
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This option disables htable to allow measurement of duplicate records.
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