This option creates IMA MOK and blacklist keyrings. IMA MOK is an
intermediate keyring that sits between .system and .ima keyrings,
effectively forming a simple CA hierarchy. To successfully import a key
into .ima_mok it must be signed by a key which CA is in .system keyring.
On turn any key that needs to go in .ima keyring must be signed by CA in
either .system or .ima_mok keyrings. IMA MOK is empty at kernel boot.
IMA blacklist keyring contains all revoked IMA keys. It is consulted
before any other keyring. If the search is successful the requested
operation is rejected and error is returned to the caller.
Signed-off-by: Petko Manolov <petkan@mip-labs.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
If file has IMA signature, IMA in enforce mode, but key is missing
then file access is blocked and single error message is printed.
If IMA appraisal is enabled in fix mode, then system runs as usual
but might produce tons of 'Request for unknown key' messages.
This patch switches 'pr_warn' to 'pr_err_ratelimited'.
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
All files on the filesystem, currently, are hashed using the same hash
algorithm. In preparation for files from different packages being
signed using different hash algorithms, this patch adds support for
reading the signature hash algorithm from the 'security.ima' extended
attribute and calculates the appropriate file data hash based on it.
Changelog:
- fix scripts Lindent and checkpatch msgs - Mimi
- fix md5 support for older version, which occupied 20 bytes in the
xattr, not the expected 16 bytes. Fix the comparison to compare
only the first 16 bytes.
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
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 <dmitry.kasatkin@intel.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Petko Manolov