cd3cec0a02
Move hardcoded IMA function calls (not appraisal-specific functions) from various places in the kernel to the LSM infrastructure, by introducing a new LSM named 'ima' (at the end of the LSM list and always enabled like 'integrity'). Having IMA before EVM in the Makefile is sufficient to preserve the relative order of the new 'ima' LSM in respect to the upcoming 'evm' LSM, and thus the order of IMA and EVM function calls as when they were hardcoded. Make moved functions as static (except ima_post_key_create_or_update(), which is not in ima_main.c), and register them as implementation of the respective hooks in the new function init_ima_lsm(). Select CONFIG_SECURITY_PATH, to ensure that the path-based LSM hook path_post_mknod is always available and ima_post_path_mknod() is always executed to mark files as new, as before the move. A slight difference is that IMA and EVM functions registered for the inode_post_setattr, inode_post_removexattr, path_post_mknod, inode_post_create_tmpfile, inode_post_set_acl and inode_post_remove_acl won't be executed for private inodes. Since those inodes are supposed to be fs-internal, they should not be of interest to IMA or EVM. The S_PRIVATE flag is used for anonymous inodes, hugetlbfs, reiserfs xattrs, XFS scrub and kernel-internal tmpfs files. Conditionally register ima_post_key_create_or_update() if CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS is enabled. Also, conditionally register ima_kernel_module_request() if CONFIG_INTEGRITY_ASYMMETRIC_KEYS is enabled. Finally, add the LSM_ID_IMA case in lsm_list_modules_test.c. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Acked-by: Chuck Lever <chuck.lever@oracle.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Christian Brauner <brauner@kernel.org> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Acked-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
10 KiB
SPDX-License-Identifier: GPL-2.0-only
IBM Integrity Measurement Architecture
config IMA bool "Integrity Measurement Architecture(IMA)" select SECURITYFS select CRYPTO select CRYPTO_HMAC select CRYPTO_SHA1 select CRYPTO_HASH_INFO select SECURITY_PATH select TCG_TPM if HAS_IOMEM select TCG_TIS if TCG_TPM && X86 select TCG_CRB if TCG_TPM && ACPI select TCG_IBMVTPM if TCG_TPM && PPC_PSERIES select INTEGRITY_AUDIT if AUDIT help The Trusted Computing Group(TCG) runtime Integrity Measurement Architecture(IMA) maintains a list of hash values of executables and other sensitive system files, as they are read or executed. If an attacker manages to change the contents of an important system file being measured, we can tell.
If your system has a TPM chip, then IMA also maintains
an aggregate integrity value over this list inside the
TPM hardware, so that the TPM can prove to a third party
whether or not critical system files have been modified.
Read <https://www.usenix.org/events/sec04/tech/sailer.html>
to learn more about IMA.
If unsure, say N.
if IMA
config IMA_KEXEC bool "Enable carrying the IMA measurement list across a soft boot" depends on TCG_TPM && HAVE_IMA_KEXEC default n help TPM PCRs are only reset on a hard reboot. In order to validate a TPM's quote after a soft boot, the IMA measurement list of the running kernel must be saved and restored on boot.
Depending on the IMA policy, the measurement list can grow to
be very large.
config IMA_MEASURE_PCR_IDX int range 8 14 default 10 help IMA_MEASURE_PCR_IDX determines the TPM PCR register index that IMA uses to maintain the integrity aggregate of the measurement list. If unsure, use the default 10.
config IMA_LSM_RULES bool depends on AUDIT && (SECURITY_SELINUX || SECURITY_SMACK || SECURITY_APPARMOR) default y help Disabling this option will disregard LSM based policy rules.
choice prompt "Default template" default IMA_NG_TEMPLATE help Select the default IMA measurement template.
The original 'ima' measurement list template contains a
hash, defined as 20 bytes, and a null terminated pathname,
limited to 255 characters. The 'ima-ng' measurement list
template permits both larger hash digests and longer
pathnames. The configured default template can be replaced
by specifying "ima_template=" on the boot command line.
config IMA_NG_TEMPLATE
bool "ima-ng (default)"
config IMA_SIG_TEMPLATE
bool "ima-sig"
endchoice
config IMA_DEFAULT_TEMPLATE string default "ima-ng" if IMA_NG_TEMPLATE default "ima-sig" if IMA_SIG_TEMPLATE
choice prompt "Default integrity hash algorithm" default IMA_DEFAULT_HASH_SHA1 help Select the default hash algorithm used for the measurement list, integrity appraisal and audit log. The compiled default hash algorithm can be overwritten using the kernel command line 'ima_hash=' option.
config IMA_DEFAULT_HASH_SHA1
bool "SHA1 (default)"
depends on CRYPTO_SHA1=y
config IMA_DEFAULT_HASH_SHA256
bool "SHA256"
depends on CRYPTO_SHA256=y
config IMA_DEFAULT_HASH_SHA512
bool "SHA512"
depends on CRYPTO_SHA512=y
config IMA_DEFAULT_HASH_WP512
bool "WP512"
depends on CRYPTO_WP512=y
config IMA_DEFAULT_HASH_SM3
bool "SM3"
depends on CRYPTO_SM3_GENERIC=y
endchoice
config IMA_DEFAULT_HASH string default "sha1" if IMA_DEFAULT_HASH_SHA1 default "sha256" if IMA_DEFAULT_HASH_SHA256 default "sha512" if IMA_DEFAULT_HASH_SHA512 default "wp512" if IMA_DEFAULT_HASH_WP512 default "sm3" if IMA_DEFAULT_HASH_SM3
config IMA_WRITE_POLICY bool "Enable multiple writes to the IMA policy" default n help IMA policy can now be updated multiple times. The new rules get appended to the original policy. Have in mind that the rules are scanned in FIFO order so be careful when you design and add new ones.
If unsure, say N.
config IMA_READ_POLICY bool "Enable reading back the current IMA policy" default y if IMA_WRITE_POLICY default n if !IMA_WRITE_POLICY help It is often useful to be able to read back the IMA policy. It is even more important after introducing CONFIG_IMA_WRITE_POLICY. This option allows the root user to see the current policy rules.
config IMA_APPRAISE bool "Appraise integrity measurements" default n help This option enables local measurement integrity appraisal. It requires the system to be labeled with a security extended attribute containing the file hash measurement. To protect the security extended attributes from offline attack, enable and configure EVM.
For more information on integrity appraisal refer to:
<http://linux-ima.sourceforge.net>
If unsure, say N.
config IMA_ARCH_POLICY
bool "Enable loading an IMA architecture specific policy"
depends on (KEXEC_SIG && IMA) || IMA_APPRAISE
&& INTEGRITY_ASYMMETRIC_KEYS
default n
help
This option enables loading an IMA architecture specific policy
based on run time secure boot flags.
config IMA_APPRAISE_BUILD_POLICY bool "IMA build time configured policy rules" depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS default n help This option defines an IMA appraisal policy at build time, which is enforced at run time without having to specify a builtin policy name on the boot command line. The build time appraisal policy rules persist after loading a custom policy.
Depending on the rules configured, this policy may require kernel
modules, firmware, the kexec kernel image, and/or the IMA policy
to be signed. Unsigned files might prevent the system from
booting or applications from working properly.
config IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS bool "Appraise firmware signatures" depends on IMA_APPRAISE_BUILD_POLICY default n help This option defines a policy requiring all firmware to be signed, including the regulatory.db. If both this option and CFG80211_REQUIRE_SIGNED_REGDB are enabled, then both signature verification methods are necessary.
config IMA_APPRAISE_REQUIRE_KEXEC_SIGS bool "Appraise kexec kernel image signatures" depends on IMA_APPRAISE_BUILD_POLICY default n help Enabling this rule will require all kexec'ed kernel images to be signed and verified by a public key on the trusted IMA keyring.
Kernel image signatures can not be verified by the original
kexec_load syscall. Enabling this rule will prevent its
usage.
config IMA_APPRAISE_REQUIRE_MODULE_SIGS bool "Appraise kernel modules signatures" depends on IMA_APPRAISE_BUILD_POLICY default n help Enabling this rule will require all kernel modules to be signed and verified by a public key on the trusted IMA keyring.
Kernel module signatures can only be verified by IMA-appraisal,
via the finit_module syscall. Enabling this rule will prevent
the usage of the init_module syscall.
config IMA_APPRAISE_REQUIRE_POLICY_SIGS bool "Appraise IMA policy signature" depends on IMA_APPRAISE_BUILD_POLICY default n help Enabling this rule will require the IMA policy to be signed and and verified by a key on the trusted IMA keyring.
config IMA_APPRAISE_BOOTPARAM bool "ima_appraise boot parameter" depends on IMA_APPRAISE default y help This option enables the different "ima_appraise=" modes (eg. fix, log) from the boot command line.
config IMA_APPRAISE_MODSIG bool "Support module-style signatures for appraisal" depends on IMA_APPRAISE depends on INTEGRITY_ASYMMETRIC_KEYS select PKCS7_MESSAGE_PARSER select MODULE_SIG_FORMAT default n help Adds support for signatures appended to files. The format of the appended signature is the same used for signed kernel modules. The modsig keyword can be used in the IMA policy to allow a hook to accept such signatures.
config IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY bool "Permit keys validly signed by a built-in, machine (if configured) or secondary" depends on SYSTEM_TRUSTED_KEYRING depends on SECONDARY_TRUSTED_KEYRING depends on INTEGRITY_ASYMMETRIC_KEYS select INTEGRITY_TRUSTED_KEYRING default n help Keys may be added to the IMA or IMA blacklist keyrings, if the key is validly signed by a CA cert in the system built-in, machine (if configured), or secondary trusted keyrings. The key must also have the digitalSignature usage set.
Intermediate keys between those the kernel has compiled in and the
IMA keys to be added may be added to the system secondary keyring,
provided they are validly signed by a key already resident in the
built-in, machine (if configured) or secondary trusted keyrings.
config IMA_BLACKLIST_KEYRING bool "Create IMA machine owner blacklist keyrings (EXPERIMENTAL)" depends on SYSTEM_TRUSTED_KEYRING depends on INTEGRITY_TRUSTED_KEYRING default n help This option creates an IMA blacklist keyring, which contains all revoked IMA keys. It is consulted before any other keyring. If the search is successful the requested operation is rejected and an error is returned to the caller.
config IMA_LOAD_X509 bool "Load X509 certificate onto the '.ima' trusted keyring" depends on INTEGRITY_TRUSTED_KEYRING default n help File signature verification is based on the public keys loaded on the .ima trusted keyring. These public keys are X509 certificates signed by a trusted key on the .system keyring. This option enables X509 certificate loading from the kernel onto the '.ima' trusted keyring.
config IMA_X509_PATH string "IMA X509 certificate path" depends on IMA_LOAD_X509 default "/etc/keys/x509_ima.der" help This option defines IMA X509 certificate path.
config IMA_APPRAISE_SIGNED_INIT bool "Require signed user-space initialization" depends on IMA_LOAD_X509 default n help This option requires user-space init to be signed.
config IMA_MEASURE_ASYMMETRIC_KEYS bool depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE=y default y
config IMA_QUEUE_EARLY_BOOT_KEYS bool depends on IMA_MEASURE_ASYMMETRIC_KEYS depends on SYSTEM_TRUSTED_KEYRING default y
config IMA_SECURE_AND_OR_TRUSTED_BOOT bool depends on IMA_ARCH_POLICY help This option is selected by architectures to enable secure and/or trusted boot based on IMA runtime policies.
config IMA_DISABLE_HTABLE bool "Disable htable to allow measurement of duplicate records" default n help This option disables htable to allow measurement of duplicate records.
endif