From: Casey Schaufler <casey@schaufler-ca.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
linux-integrity <linux-integrity@vger.kernel.org>
Cc: LSM <linux-security-module@vger.kernel.org>,
Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: evm_inode_init_security and module stacking
Date: Fri, 18 Jan 2019 10:49:07 -0800 [thread overview]
Message-ID: <9e142269-fd2e-b62e-f3fc-687d400aefd1@schaufler-ca.com> (raw)
In-Reply-To: <1547778689.3982.20.camel@linux.ibm.com>
On 1/17/2019 6:31 PM, Mimi Zohar wrote:
> On Thu, 2019-01-17 at 16:47 -0800, Casey Schaufler wrote:
>> security_inode_init_security() currently calls at most one
>> of selinux_inode_init_security() and smack_inode_init_security().
>> It then sends the result to evm_inode_init_security to create
>> the security.evm attribute. This isn't going to work on a system
>> that has both SELinux and Smack.
> Calculating security.evm based on multiple xattrs sounded really
> familiar. Looking back at the git log, 9d8f13ba3f48 ("security: new
> security_inode_init_security API adds function callback") addressed
> filesystems wanting to be able to write all the xattrs at the same
> time and prepared for multiple LSM xattr support.
Right. That provides for security.selinux, security.SMACK64
and security.evm at the same time. What it doesn't help with
is what goes into security.evm.
>> I see two options:
>> - create security.evm with the information from all
>> security modules that provide inode_init_security hooks
>> - create a separate attribute for each module,
>> security.evm-selinux and security.evm-smack in the
>> current case.
>>
>> How would you like to have it work? I am agnostic, although the
>> separate attributes would be easier for the infrastructure.
> Having separate attributes for each LSM module would require re-
> calculating the hmac for each one, any time any of the other file
> metadata changed. That doesn't sound like a good idea.
OK. So it sounds like I need to gather up data from all of the
LSMs (e.g. security.selinux, security.SMACK64) and pass the combination
to evm_inode_init_security(). Will that work? Will that provide the
integrity sub-system what it needs?
> Mimi
next prev parent reply other threads:[~2019-01-18 18:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 0:47 evm_inode_init_security and module stacking Casey Schaufler
2019-01-18 2:31 ` Mimi Zohar
2019-01-18 18:49 ` Casey Schaufler [this message]
2019-01-20 16:42 ` Mimi Zohar
2019-01-20 18:54 ` Casey Schaufler
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