linux/security/integrity, branch v5.15

Merge tag 'integrity-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

2021-09-02T19:51:41Z

Pull integrity subsystem updates from Mimi Zohar: - Limit the allowed hash algorithms when writing security.ima xattrs or verifying them, based on the IMA policy and the configured hash algorithms. - Return the calculated "critical data" measurement hash and size to avoid code duplication. (Preparatory change for a proposed LSM.) - and a single patch to address a compiler warning. * tag 'integrity-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: IMA: reject unknown hash algorithms in ima_get_hash_algo IMA: prevent SETXATTR_CHECK policy rules with unavailable algorithms IMA: introduce a new policy option func=SETXATTR_CHECK IMA: add a policy option to restrict xattr hash algorithms on appraisal IMA: add support to restrict the hash algorithms used for file appraisal IMA: block writes of the security.ima xattr with unsupported algorithms IMA: remove the dependency on CRYPTO_MD5 ima: Add digest and digest_len params to the functions to measure a buffer ima: Return int in the functions to measure a buffer ima: Introduce ima_get_current_hash_algo() IMA: remove -Wmissing-prototypes warning

Merge tag 'for-5.15/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2021-08-31T21:55:09Z

Pull device mapper updates from Mike Snitzer: - Add DM infrastructure for IMA-based remote attestion. These changes are the basis for deploying DM-based storage in a "cloud" that must validate configurations end-users run to maintain trust. These DM changes allow supported DM targets' configurations to be measured via IMA. But the policy and enforcement (of which configurations are valid) is managed by something outside the kernel (e.g. Keylime). - Fix DM crypt scalability regression on systems with many cpus due to percpu_counter spinlock contention in crypt_page_alloc(). - Use in_hardirq() instead of deprecated in_irq() in DM crypt. - Add event counters to DM writecache to allow users to further assess how the writecache is performing. - Various code cleanup in DM writecache's main IO mapping function. * tag 'for-5.15/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm crypt: use in_hardirq() instead of deprecated in_irq() dm ima: update dm documentation for ima measurement support dm ima: update dm target attributes for ima measurements dm ima: add a warning in dm_init if duplicate ima events are not measured dm ima: prefix ima event name related to device mapper with dm_ dm ima: add version info to dm related events in ima log dm ima: prefix dm table hashes in ima log with hash algorithm dm crypt: Avoid percpu_counter spinlock contention in crypt_page_alloc() dm: add documentation for IMA measurement support dm: update target status functions to support IMA measurement dm ima: measure data on device rename dm ima: measure data on table clear dm ima: measure data on device remove dm ima: measure data on device resume dm ima: measure data on table load dm writecache: add event counters dm writecache: report invalid return from writecache_map helpers dm writecache: further writecache_map() cleanup dm writecache: factor out writecache_map_remap_origin() dm writecache: split up writecache_map() to improve code readability

efi: Don't use knowledge about efi_guid_t internals

2021-08-27T14:01:27Z

When print GUIDs supply pointer to the efi_guid_t (guid_t) type rather its internal members. Signed-off-by: Andy Shevchenko Reviewed-by: Serge Hallyn Signed-off-by: Ard Biesheuvel

IMA: reject unknown hash algorithms in ima_get_hash_algo

2021-08-23T22:22:00Z

The new function validate_hash_algo() assumed that ima_get_hash_algo() always return a valid 'enum hash_algo', but it returned the user-supplied value present in the digital signature without any bounds checks. Update ima_get_hash_algo() to always return a valid hash algorithm, defaulting on 'ima_hash_algo' when the user-supplied value inside the xattr is invalid. Signed-off-by: THOBY Simon Reported-by: syzbot+e8bafe7b82c739eaf153@syzkaller.appspotmail.com Fixes: 50f742dd9147 ("IMA: block writes of the security.ima xattr with unsupported algorithms") Reviewed-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar

IMA: prevent SETXATTR_CHECK policy rules with unavailable algorithms

2021-08-16T21:35:35Z

SETXATTR_CHECK policy rules assume that any algorithm listed in the 'appraise_algos' flag must be accepted when performing setxattr() on the security.ima xattr. However nothing checks that they are available in the current kernel. A userland application could hash a file with a digest that the kernel wouldn't be able to verify. However, if SETXATTR_CHECK is not in use, the kernel already forbids that xattr write. Verify that algorithms listed in appraise_algos are available to the current kernel and reject the policy update otherwise. This will fix the inconsistency between SETXATTR_CHECK and non-SETXATTR_CHECK behaviors. That filtering is only performed in ima_parse_appraise_algos() when updating policies so that we do not have to pay the price of allocating a hash object every time validate_hash_algo() is called in ima_inode_setxattr(). Signed-off-by: THOBY Simon Signed-off-by: Mimi Zohar

IMA: introduce a new policy option func=SETXATTR_CHECK

2021-08-16T21:35:35Z

While users can restrict the accepted hash algorithms for the security.ima xattr file signature when appraising said file, users cannot restrict the algorithms that can be set on that attribute: any algorithm built in the kernel is accepted on a write. Define a new value for the ima policy option 'func' that restricts globally the hash algorithms accepted when writing the security.ima xattr. When a policy contains a rule of the form appraise func=SETXATTR_CHECK appraise_algos=sha256,sha384,sha512 only values corresponding to one of these three digest algorithms will be accepted for writing the security.ima xattr. Attempting to write the attribute using another algorithm (or "free-form" data) will be denied with an audit log message. In the absence of such a policy rule, the default is still to only accept hash algorithms built in the kernel (with all the limitations that entails). Signed-off-by: THOBY Simon Reviewed-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar

IMA: add a policy option to restrict xattr hash algorithms on appraisal

2021-08-16T21:33:07Z

The kernel has the ability to restrict the set of hash algorithms it accepts for the security.ima xattr when it appraises files. Define a new IMA policy rule option "appraise_algos=", using the mentioned mechanism to expose a user-toggable policy knob to opt-in to that restriction and select the desired set of algorithms that must be accepted. When a policy rule uses the 'appraise_algos' option, appraisal of a file referenced by that rule will now fail if the digest algorithm employed to hash the file was not one of those explicitly listed in the option. In its absence, any hash algorithm compiled in the kernel will be accepted. For example, on a system where SELinux is properly deployed, the rule appraise func=BPRM_CHECK obj_type=iptables_exec_t \ appraise_algos=sha256,sha384 will block the execution of iptables if the xattr security.ima of its executables were not hashed with either sha256 or sha384. Signed-off-by: THOBY Simon Reviewed-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar

IMA: add support to restrict the hash algorithms used for file appraisal

2021-08-16T21:30:41Z

The kernel accepts any hash algorithm as a value for the security.ima xattr. Users may wish to restrict the accepted algorithms to only support strong cryptographic ones. Provide the plumbing to restrict the permitted set of hash algorithms used for verifying file hashes and signatures stored in security.ima xattr. Signed-off-by: THOBY Simon Reviewed-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar

IMA: block writes of the security.ima xattr with unsupported algorithms

2021-08-16T21:30:41Z

By default, writes to the extended attributes security.ima will be allowed even if the hash algorithm used for the xattr is not compiled in the kernel (which does not make sense because the kernel would not be able to appraise that file as it lacks support for validating the hash). Prevent and audit writes to the security.ima xattr if the hash algorithm used in the new value is not available in the current kernel. Signed-off-by: THOBY Simon Reviewed-by: Lakshmi Ramasubramanian 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