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From: Roberto S. <rob...@po...> - 2010-04-14 09:52:37
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Description of the issue:
There is a variety of criteria that can be used to determine if a file must be
measured or not; an useful feature of recent versions of IMA is the ability
of take measure decisions depending on the label assigned by a "Mandatory
Access Control" to a process which is accessing a file or depending on the
object label itself.
In general these data, i.e. the subject and the object labels, can be used
during the "Remote Attestation" by a verifier to better evaluate if a trust
relationship should be established with the remote peer: for example if
it wants to check the integrity only of the sshd server, it can
examine the executable and libraries mapped in the process assigned memory by
selecting, from the list of measurements with enhanced format, the rows
with subject label "sshd_t".
This is just a possible check that can be done: to evaluate the integrity
of a generic software component, the verifier must know what Mandatory Access
Control is being executed on the remote system and the relative policy since
the latter is where labels and rules are defined.
The current format of the measurement list is:
| PCR extended | template digest | ima | event digest | event name |
Solution proposed:
The new format proposed adds two new fields:
| PCR extended | template digest | ima | event digest | event name | subject
label | object label |
The added data is retrieved in "ima_store_measurement" by calling the function
"security_secid_to_secctx".
Since the template digest is obtained by performing the SHA1 of "event digest"
and "event name", in the patched code even the two added fields have been
included in the hash operation.
This patch set applies to kernel 2.6.32 series and 2.6.33 series.
Roberto Sassu (1):
ima: extending the format of the measurement list
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