linux/security/integrity/evm
Roberto Sassu 8c7a703ec9 evm: Verify portable signatures against all protected xattrs
Currently, the evm_config_default_xattrnames array contains xattr names
only related to LSMs which are enabled in the kernel configuration.
However, EVM portable signatures do not depend on local information and a
vendor might include in the signature calculation xattrs that are not
enabled in the target platform.

Just including all xattrs names in evm_config_default_xattrnames is not a
safe approach, because a target system might have already calculated
signatures or HMACs based only on the enabled xattrs. After applying this
patch, EVM would verify those signatures and HMACs with all xattrs instead.
The non-enabled ones, which could possibly exist, would cause a
verification error.

Thus, this patch adds a new field named enabled to the xattr_list
structure, which is set to true if the LSM associated to a given xattr name
is enabled in the kernel configuration. The non-enabled xattrs are taken
into account only in evm_calc_hmac_or_hash(), if the passed security.evm
type is EVM_XATTR_PORTABLE_DIGSIG.

The new function evm_protected_xattr_if_enabled() has been defined so that
IMA can include all protected xattrs and not only the enabled ones in the
measurement list, if the new template fields xattrnames, xattrlengths or
xattrvalues have been included in the template format.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-01 15:17:31 -04:00
..
evm_crypto.c evm: Verify portable signatures against all protected xattrs 2021-06-01 15:17:31 -04:00
evm_main.c evm: Verify portable signatures against all protected xattrs 2021-06-01 15:17:31 -04:00
evm_posix_acl.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
evm_secfs.c evm: Verify portable signatures against all protected xattrs 2021-06-01 15:17:31 -04:00
evm.h evm: Verify portable signatures against all protected xattrs 2021-06-01 15:17:31 -04:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00