linux-dev/security/integrity/ima/Kconfig, branch master

ima: remove the IMA_TEMPLATE Kconfig option

2022-04-07T12:48:20Z

The original 'ima' measurement list template contains a hash, defined as 20 bytes, and a null terminated pathname, limited to 255 characters. Other measurement list templates permit both larger hashes and longer pathnames. When the "ima" template is configured as the default, a new measurement list template (ima_template=) must be specified before specifying a larger hash algorithm (ima_hash=) on the boot command line. To avoid this boot command line ordering issue, remove the legacy "ima" template configuration option, allowing it to still be specified on the boot command line. The root cause of this issue is that during the processing of ima_hash, we would try to check whether the hash algorithm is compatible with the template. If the template is not set at the moment we do the check, we check the algorithm against the configured default template. If the default template is "ima", then we reject any hash algorithm other than sha1 and md5. For example, if the compiled default template is "ima", and the default algorithm is sha1 (which is the current default). In the cmdline, we put in "ima_hash=sha256 ima_template=ima-ng". The expected behavior would be that ima starts with ima-ng as the template and sha256 as the hash algorithm. However, during the processing of "ima_hash=", "ima_template=" has not been processed yet, and hash_setup would check the configured hash algorithm against the compiled default: ima, and reject sha256. So at the end, the hash algorithm that is actually used will be sha1. With template "ima" removed from the configured default, we ensure that the default tempalte would at least be "ima-ng" which allows for basically any hash algorithm. This change would not break the algorithm compatibility checks for IMA. Fixes: 4286587dccd43 ("ima: add Kconfig default measurement list template") Signed-off-by: GUO Zihua Cc: Signed-off-by: Mimi Zohar

IMA: remove the dependency on CRYPTO_MD5

2021-08-16T21:29:10Z

MD5 is a weak digest algorithm that shouldn't be used for cryptographic operation. It hinders the efficiency of a patch set that aims to limit the digests allowed for the extended file attribute namely security.ima. MD5 is no longer a requirement for IMA, nor should it be used there. The sole place where we still use the MD5 algorithm inside IMA is setting the ima_hash algorithm to MD5, if the user supplies 'ima_hash=md5' parameter on the command line. With commit ab60368ab6a4 ("ima: Fallback to the builtin hash algorithm"), setting "ima_hash=md5" fails gracefully when CRYPTO_MD5 is not set: ima: Can not allocate md5 (reason: -2) ima: Allocating md5 failed, going to use default hash algorithm sha256 Remove the CRYPTO_MD5 dependency for IMA. Signed-off-by: THOBY Simon Reviewed-by: Lakshmi Ramasubramanian [zohar@linux.ibm.com: include commit number in patch description for stable.] Cc: stable@vger.kernel.org # 4.17 Signed-off-by: Mimi Zohar

IMA: support for duplicate measurement records

2021-06-11T16:54:13Z

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 Reviewed-by: Petr Vorel [zohar@linux.ibm.com: updated list of duplicate measurement records] Signed-off-by: Mimi Zohar

Merge tag 'for-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2020-08-11T21:30:36Z

Pull security subsystem updates from James Morris: "A couple of minor documentation updates only for this release" * tag 'for-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: LSM: drop duplicated words in header file comments Replace HTTP links with HTTPS ones: security

Replace HTTP links with HTTPS ones: security

2020-08-06T19:00:05Z

Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov Acked-by: John Johansen Signed-off-by: James Morris

ima: move APPRAISE_BOOTPARAM dependency on ARCH_POLICY to runtime

2020-07-20T22:18:49Z

The IMA_APPRAISE_BOOTPARAM config allows enabling different "ima_appraise=" modes - log, fix, enforce - at run time, but not when IMA architecture specific policies are enabled. This prevents properly labeling the filesystem on systems where secure boot is supported, but not enabled on the platform. Only when secure boot is actually enabled should these IMA appraise modes be disabled. This patch removes the compile time dependency and makes it a runtime decision, based on the secure boot state of that platform. Test results as follows: -> x86-64 with secure boot enabled [ 0.015637] Kernel command line: <...> ima_policy=appraise_tcb ima_appraise=fix [ 0.015668] ima: Secure boot enabled: ignoring ima_appraise=fix boot parameter option -> powerpc with secure boot disabled [ 0.000000] Kernel command line: <...> ima_policy=appraise_tcb ima_appraise=fix [ 0.000000] Secure boot mode disabled -> Running the system without secure boot and with both options set: CONFIG_IMA_APPRAISE_BOOTPARAM=y CONFIG_IMA_ARCH_POLICY=y Audit prompts "missing-hash" but still allow execution and, consequently, filesystem labeling: type=INTEGRITY_DATA msg=audit(07/09/2020 12:30:27.778:1691) : pid=4976 uid=root auid=root ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 op=appraise_data cause=missing-hash comm=bash name=/usr/bin/evmctl dev="dm-0" ino=493150 res=no Cc: stable@vger.kernel.org Fixes: d958083a8f64 ("x86/ima: define arch_get_ima_policy() for x86") Signed-off-by: Bruno Meneguele Cc: stable@vger.kernel.org # 5.0 Signed-off-by: Mimi Zohar

ima: AppArmor satisfies the audit rule requirements

2020-07-20T22:18:37Z

AppArmor meets all the requirements for IMA in terms of audit rules since commit e79c26d04043 ("apparmor: Add support for audit rule filtering"). Update IMA's Kconfig section for CONFIG_IMA_LSM_RULES to reflect this. Fixes: e79c26d04043 ("apparmor: Add support for audit rule filtering") Signed-off-by: Tyler Hicks Signed-off-by: Mimi Zohar

ima: add a new CONFIG for loading arch-specific policies

2020-03-12T11:43:57Z

Every time a new architecture defines the IMA architecture specific functions - arch_ima_get_secureboot() and arch_ima_get_policy(), the IMA include file needs to be updated. To avoid this "noise", this patch defines a new IMA Kconfig IMA_SECURE_AND_OR_TRUSTED_BOOT option, allowing the different architectures to select it. Suggested-by: Linus Torvalds Signed-off-by: Nayna Jain Acked-by: Ard Biesheuvel Acked-by: Philipp Rudo (s390) Acked-by: Michael Ellerman (powerpc) Signed-off-by: Mimi Zohar

ima: add sm3 algorithm to hash algorithm configuration list

2020-02-18T12:35:49Z

sm3 has been supported by the ima hash algorithm, but it is not yet in the Kconfig configuration list. After adding, both ima and tpm2 can support sm3 well. Signed-off-by: Tianjia Zhang Signed-off-by: Mimi Zohar

IMA: Define workqueue for early boot key measurements

2020-01-23T12:35:11Z

Measuring keys requires a custom IMA policy to be loaded. Keys created or updated before a custom IMA policy is loaded should be queued and will be processed after a custom policy is loaded. This patch defines a workqueue for queuing keys when a custom IMA policy has not yet been loaded. An intermediate Kconfig boolean option namely IMA_QUEUE_EARLY_BOOT_KEYS is used to declare the workqueue functions. A flag namely ima_process_keys is used to check if the key should be queued or should be processed immediately. Signed-off-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar