kernel.git/security/integrity/evm/evm_main.c, branch linux-3.9.y

evm: add file system uuid to EVM hmac

2013-02-06T15:40:28Z

EVM uses the same key for all file systems to calculate the HMAC, making it possible to paste inodes from one file system on to another one, without EVM being able to detect it. To prevent such an attack, it is necessary to make the EVM HMAC file system specific. This patch uses the file system UUID, a file system unique identifier, to bind the EVM HMAC to the file system. The value inode->i_sb->s_uuid is used for the HMAC hash calculation, instead of using it for deriving the file system specific key. Initializing the key for every inode HMAC calculation is a bit more expensive operation than adding the uuid to the HMAC hash. Changing the HMAC calculation method or adding additional info to the calculation, requires existing EVM labeled file systems to be relabeled. This patch adds a Kconfig HMAC version option for backwards compatability. Changelog v1: - squash "hmac version setting" Changelog v0: - add missing Kconfig depends (Mimi) Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

evm: remove unused cleanup functions

2013-01-16T20:47:05Z

EVM cannot be built as a kernel module. Remove the unncessary __exit functions. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: integrity appraisal extension

2012-09-07T18:57:44Z

IMA currently maintains an integrity measurement list used to assert the integrity of the running system to a third party. The IMA-appraisal extension adds local integrity validation and enforcement of the measurement against a "good" value stored as an extended attribute 'security.ima'. The initial methods for validating 'security.ima' are hashed based, which provides file data integrity, and digital signature based, which in addition to providing file data integrity, provides authenticity. This patch creates and maintains the 'security.ima' xattr, containing the file data hash measurement. Protection of the xattr is provided by EVM, if enabled and configured. Based on policy, IMA calls evm_verifyxattr() to verify a file's metadata integrity and, assuming success, compares the file's current hash value with the one stored as an extended attribute in 'security.ima'. Changelov v4: - changed iint cache flags to hex values Changelog v3: - change appraisal default for filesystems without xattr support to fail Changelog v2: - fix audit msg 'res' value - removed unused 'ima_appraise=' values Changelog v1: - removed unused iint mutex (Dmitry Kasatkin) - setattr hook must not reset appraised (Dmitry Kasatkin) - evm_verifyxattr() now differentiates between no 'security.evm' xattr (INTEGRITY_NOLABEL) and no EVM 'protected' xattrs included in the 'security.evm' (INTEGRITY_NOXATTRS). - replace hash_status with ima_status (Dmitry Kasatkin) - re-initialize slab element ima_status on free (Dmitry Kasatkin) - include 'security.ima' in EVM if CONFIG_IMA_APPRAISE, not CONFIG_IMA - merged half "ima: ima_must_appraise_or_measure API change" (Dmitry Kasatkin) - removed unnecessary error variable in process_measurement() (Dmitry Kasatkin) - use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured (moved ima_inode_post_setattr() to ima_appraise.c) - make sure ima_collect_measurement() can read file Changelog: - add 'iint' to evm_verifyxattr() call (Dimitry Kasatkin) - fix the race condition between chmod, which takes the i_mutex and then iint->mutex, and ima_file_free() and process_measurement(), which take the locks in the reverse order, by eliminating iint->mutex. (Dmitry Kasatkin) - cleanup of ima_appraise_measurement() (Dmitry Kasatkin) - changes as a result of the iint not allocated for all regular files, but only for those measured/appraised. - don't try to appraise new/empty files - expanded ima_appraisal description in ima/Kconfig - IMA appraise definitions required even if IMA_APPRAISE not enabled - add return value to ima_must_appraise() stub - unconditionally set status = INTEGRITY_PASS *after* testing status, not before. (Found by Joe Perches) Signed-off-by: Mimi Zohar Signed-off-by: Dmitry Kasatkin

evm: digital signature verification support

2011-11-09T14:51:14Z

This patch adds support for digital signature verification to EVM. With this feature file metadata can be protected using digital signature instead of an HMAC. When building an image, which has to be flashed to different devices, an HMAC cannot be used to sign file metadata, because the HMAC key should be different on every device. Signed-off-by: Dmitry Kasatkin Acked-by: Mimi Zohar

evm: permit mode bits to be updated

2011-09-14T19:24:52Z

Before permitting 'security.evm' to be updated, 'security.evm' must exist and be valid. In the case that there are no existing EVM protected xattrs, it is safe for posix acls to update the mode bits. To differentiate between no 'security.evm' xattr and no xattrs used to calculate 'security.evm', this patch defines INTEGRITY_NOXATTR. Signed-off-by: Mimi Zohar

evm: posix acls modify i_mode

2011-09-14T19:24:51Z

The posix xattr acls are 'system' prefixed, which normally would not affect security.evm. An interesting side affect of writing posix xattr acls is their modifying of the i_mode, which is included in security.evm. This patch updates security.evm when posix xattr acls are written. Signed-off-by: Mimi Zohar

evm: limit verifying current security.evm integrity

2011-09-14T19:24:51Z

evm_protect_xattr unnecessarily validates the current security.evm integrity, before updating non-evm protected extended attributes and other file metadata. This patch limits validating the current security.evm integrity to evm protected metadata. Signed-off-by: Mimi Zohar

evm: fix evm_inode_init_security return code

2011-08-11T07:42:41Z

evm_inode_init_security() should return 0, when EVM is not enabled. (Returning an error is a remnant of evm_inode_post_init_security.) Signed-off-by: Mimi Zohar Signed-off-by: James Morris

evm: add evm_inode_setattr to prevent updating an invalid security.evm

2011-07-18T16:29:50Z

Permit changing of security.evm only when valid, unless in fixmode. Reported-by: Roberto Sassu Signed-off-by: Mimi Zohar

evm: permit only valid security.evm xattrs to be updated

2011-07-18T16:29:49Z

In addition to requiring CAP_SYS_ADMIN permission to modify/delete security.evm, prohibit invalid security.evm xattrs from changing, unless in fixmode. This patch prevents inadvertent 'fixing' of security.evm to reflect offline modifications. Changelog v7: - rename boot paramater 'evm_mode' to 'evm' Reported-by: Roberto Sassu Signed-off-by: Mimi Zohar