kernel/linux.git/security/integrity/integrity.h, branch v3.10.61

ima: digital signature verification using asymmetric keys

2013-02-07T02:22:18+00:00

Asymmetric keys were introduced in linux-3.7 to verify the signature on signed kernel modules. The asymmetric keys infrastructure abstracts the signature verification from the crypto details. This patch adds IMA/EVM signature verification using asymmetric keys. Support for additional signature verification methods can now be delegated to the asymmetric key infrastructure. Although the module signature header and the IMA/EVM signature header could use the same format, to minimize the signature length and save space in the extended attribute, this patch defines a new IMA/EVM header format. The main difference is that the key identifier is a sha1[12 - 19] hash of the key modulus and exponent, similar to the current implementation. The only purpose of the key identifier is to identify the corresponding key in the kernel keyring. ima-evm-utils was updated to support the new signature format. While asymmetric signature verification functionality supports many different hash algorithms, the hash used in this patch is calculated during the IMA collection phase, based on the configured algorithm. The default algorithm is sha1, but for backwards compatibility md5 is supported. Due to this current limitation, signatures should be generated using a sha1 hash algorithm. Changes in this patch: - Functionality has been moved to separate source file in order to get rid of in source #ifdefs. - keyid is derived according to the RFC 3280. It does not require to assign IMA/EVM specific "description" when loading X509 certificate. Kernel asymmetric key subsystem automatically generate the description. Also loading a certificate does not require using of ima-evm-utils and can be done using keyctl only. - keyid size is reduced to 32 bits to save xattr space. Key search is done using partial match functionality of asymmetric_key_match(). - Kconfig option title was changed Signed-off-by: Dmitry Kasatkin Acked-by: David Howells Signed-off-by: Mimi Zohar

ima: per hook cache integrity appraisal status

2013-01-22T21:10:36+00:00

With the new IMA policy 'appraise_type=' option, different hooks can require different methods for appraising a file's integrity. For example, the existing 'ima_appraise_tcb' policy defines a generic rule, requiring all root files to be appraised, without specfying the appraisal method. A more specific rule could require all kernel modules, for example, to be signed. appraise fowner=0 func=MODULE_CHECK appraise_type=imasig appraise fowner=0 As a result, the integrity appraisal results for the same inode, but for different hooks, could differ. This patch caches the integrity appraisal results on a per hook basis. Changelog v2: - Rename ima_cache_status() to ima_set_cache_status() - Rename and move get_appraise_status() to ima_get_cache_status() Changelog v0: - include IMA_APPRAISE/APPRAISED_SUBMASK in IMA_DO/DONE_MASK (Dmitry) - Support independent MODULE_CHECK appraise status. - fixed IMA_XXXX_APPRAISE/APPRAISED flags Signed-off-by: Mimi Zohar Signed-off-by: Dmitry Kasatkin

ima: increase iint flag size

2013-01-22T21:10:34+00:00

In preparation for hook specific appraise status results, increase the iint flags size. Signed-off-by: Mimi Zohar Signed-off-by: Dmitry Kasatkin

ima: added policy support for 'security.ima' type

2013-01-22T21:10:31+00:00

The 'security.ima' extended attribute may contain either the file data's hash or a digital signature. This patch adds support for requiring a specific extended attribute type. It extends the IMA policy with a new keyword 'appraise_type=imasig'. (Default is hash.) Changelog v2: - Fixed Documentation/ABI/testing/ima_policy option syntax Changelog v1: - Differentiate between 'required' vs. 'actual' extended attribute Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

integrity: reduce storage size for ima_status and evm_status

2013-01-16T22:50:01+00:00

This patch reduces size of the iint structure by 8 bytes. It saves about 15% of iint cache memory. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: change flags container data type

2012-09-19T12:55:20+00:00

IMA audit hashes patches introduced new IMA flags and required space went beyond 8 bits. Currently the only flag is IMA_DIGSIG. This patch use 16 bit short instead of 8 bit char. Without this fix IMA signature will be replaced with hash, which should not happen. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: audit log hashes

2012-09-13T18:48:44+00:00

This adds an 'audit' policy action which audit logs file measurements. Changelog v6: - use new action flag handling (Dmitry Kasatkin). - removed whitespace (Mimi) Changelog v5: - use audit_log_untrustedstring. Changelog v4: - cleanup digest -> hash conversion. - use filename rather than d_path in ima_audit_measurement. Changelog v3: - Use newly exported audit_log_task_info for logging pid/ppid/uid/etc. - Update the ima_policy ABI documentation. Changelog v2: - Use 'audit' action rather than 'measure_and_audit' to permit auditing in the absence of measuring.. Changelog v1: - Initial posting. Signed-off-by: Peter Moody Signed-off-by: Mimi Zohar

ima: generic IMA action flag handling

2012-09-13T18:23:57+00:00

Make the IMA action flag handling generic in order to support additional new actions, without requiring changes to the base implementation. New actions, like audit logging, will only need to modify the define statements. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: digital signature verification support

2012-09-07T18:57:48+00:00

This patch adds support for digital signature based integrity appraisal. With this patch, 'security.ima' contains either the file data hash or a digital signature of the file data hash. The file data hash provides the security attribute of file integrity. In addition to file integrity, a digital signature provides the security attribute of authenticity. Unlike EVM, when the file metadata changes, the digital signature is replaced with an HMAC, modification of the file data does not cause the 'security.ima' digital signature to be replaced with a hash. As a result, after any modification, subsequent file integrity appraisals would fail. Although digitally signed files can be modified, but by not updating 'security.ima' to reflect these modifications, in essence digitally signed files could be considered 'immutable'. IMA uses a different keyring than EVM. While the EVM keyring should not be updated after initialization and locked, the IMA keyring should allow updating or adding new keys when upgrading or installing packages. Changelog v4: - Change IMA_DIGSIG to hex equivalent Changelog v3: - Permit files without any 'security.ima' xattr to be labeled properly. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: add support for different security.ima data types

2012-09-07T18:57:47+00:00

IMA-appraisal currently verifies the integrity of a file based on a known 'good' measurement value. This patch reserves the first byte of 'security.ima' as a place holder for the type of method used for verifying file data integrity. Changelog v1: - Use the newly defined 'struct evm_ima_xattr_data' Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar