From: Mimi Zohar <zohar@linux.ibm.com>
To: Roberto Sassu <roberto.sassu@huawei.com>, mjg59@srcf.ucam.org
Cc: linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/7] evm: Verify portable signatures against all protected xattrs
Date: Mon, 24 May 2021 14:21:43 -0400 [thread overview]
Message-ID: <17d48530e2ec9a6f7e2cb868d8ddf8dcd3be14da.camel@linux.ibm.com> (raw)
In-Reply-To: <20210520085701.465369-6-roberto.sassu@huawei.com>
On Thu, 2021-05-20 at 10:56 +0200, Roberto Sassu wrote:
> 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 in only 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 field evmxattrs has been included in
> the template format.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Nice, I really like this idea.
Mimi
next prev parent reply other threads:[~2021-05-24 18:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 8:56 [PATCH 0/7] ima: Add template fields to verify EVM portable signatures Roberto Sassu
2021-05-20 8:56 ` [PATCH 1/7] ima: Add ima_show_template_uint() template library function Roberto Sassu
2021-05-20 8:56 ` [PATCH 2/7] ima: Introduce template fields iuid and igid Roberto Sassu
2021-05-20 8:56 ` [PATCH 3/7] ima: Introduce template fields mntuidmap and mntgidmap Roberto Sassu
2021-05-20 9:36 ` Christian Brauner
2021-05-20 9:41 ` Christian Brauner
2021-05-20 11:54 ` Roberto Sassu
2021-05-20 8:56 ` [PATCH 4/7] ima: Introduce template field imode Roberto Sassu
2021-05-20 8:56 ` [PATCH 5/7] evm: Verify portable signatures against all protected xattrs Roberto Sassu
2021-05-24 18:21 ` Mimi Zohar [this message]
2021-05-20 8:57 ` [PATCH 6/7] ima: Introduce template field evmxattrs Roberto Sassu
2021-05-24 18:31 ` Mimi Zohar
2021-05-20 8:57 ` [PATCH 7/7] evm: Don't return an error in evm_write_xattrs() if audit is not enabled Roberto Sassu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=17d48530e2ec9a6f7e2cb868d8ddf8dcd3be14da.camel@linux.ibm.com \
--to=zohar@linux.ibm.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=mjg59@srcf.ucam.org \
--cc=roberto.sassu@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).