Skip to content

L
linux
Switch branch/tag
  1. 01 May, 2022 2 commits
    • Mimi Zohar's avatar
      ima: use IMA default hash algorithm for integrity violations · 09091c44
      Mimi Zohar authored 
      Integrity file violations - ToM/ToU, open writers - are recorded in the IMA
measurement list, containing 0x00's in both the template data and file data
hash fields, but 0xFF's are actually extended into TPM PCRs.  Although the
original 'ima' template data field ('d') is limited to 20 bytes, the 'd-ng'
template digest field is not.

The violation file data hash template field ('d-ng') is unnecessarily hard
coded to SHA1.  Instead of simply replacing the hard coded SHA1 hash
algorithm with a larger hash algorithm, use the hash algorithm as defined
in "ima_hash_algo".  ima_hash_algo is set to either the Kconfig IMA default
hash algorithm or as defined on the boot command line (ima_hash=).

Including a non-SHA1 file data hash algorithm in the 'd-ng' field of
violations is a cosmetic change.  The template data hash field, which is
extended into the TPM PCRs, is not affected by this change and should not
affect attestation of the IMA measurement list.
Tested-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
      09091c44
    • Mimi Zohar's avatar
      ima: fix 'd-ng' comments and documentation · 64466462
      Mimi Zohar authored 
      Initially the 'd-ng' template field did not prefix the digest with either
"md5" or "sha1" hash algorithms.  Prior to being upstreamed this changed,
but the comments and documentation were not updated.  Fix the comments
and documentation.

Fixes: 4d7aeee7 ("ima: define new template ima-ng and template fields d-ng and n-ng")
Reported-by: default avatarEric Biggers <ebiggers@kernel.org>
Reviewed-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
      64466462
  3. 07 Apr, 2022 1 commit
    • GUO Zihua's avatar
      ima: remove the IMA_TEMPLATE Kconfig option · 891163ad
      GUO Zihua authored 
      The original 'ima' measurement list template contains a hash, defined
as 20 bytes, and a null terminated pathname, limited to 255
characters.  Other measurement list templates permit both larger hashes
and longer pathnames.  When the "ima" template is configured as the
default, a new measurement list template (ima_template=) must be
specified before specifying a larger hash algorithm (ima_hash=) on the
boot command line.

To avoid this boot command line ordering issue, remove the legacy "ima"
template configuration option, allowing it to still be specified on the
boot command line.

The root cause of this issue is that during the processing of ima_hash,
we would try to check whether the hash algorithm is compatible with the
template. If the template is not set at the moment we do the check, we
check the algorithm against the configured default template. If the
default template is "ima", then we reject any hash algorithm other than
sha1 and md5.

For example, if the compiled default template is "ima", and the default
algorithm is sha1 (which is the current default). In the cmdline, we put
in "ima_hash=sha256 ima_template=ima-ng". The expected behavior would be
that ima starts with ima-ng as the template and sha256 as the hash
algorithm. However, during the processing of "ima_hash=",
"ima_template=" has not been processed yet, and hash_setup would check
the configured hash algorithm against the compiled default: ima, and
reject sha256. So at the end, the hash algorithm that is actually used
will be sha1.

With template "ima" removed from the configured default, we ensure that
the default tempalte would at least be "ima-ng" which allows for
basically any hash algorithm.

This change would not break the algorithm compatibility checks for IMA.

Fixes: 4286587d ("ima: add Kconfig default measurement list template")
Signed-off-by: default avatarGUO Zihua <guozihua@huawei.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
      891163ad
  5. 04 Apr, 2022 1 commit
  7. 03 Apr, 2022 8 commits
  9. 02 Apr, 2022 28 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7