From: Mimi Zohar <zohar@linux.ibm.com>
To: Roberto Sassu <roberto.sassu@huawei.com>,
"matthewgarrett@google.com" <matthewgarrett@google.com>
Cc: "linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
Silviu Vlasceanu <Silviu.Vlasceanu@huawei.com>
Subject: Re: Immutable metadata
Date: Mon, 30 Mar 2020 11:46:43 -0400 [thread overview]
Message-ID: <1585583203.5188.418.camel@linux.ibm.com> (raw)
In-Reply-To: <1585534223.5188.408.camel@linux.ibm.com>
On Sun, 2020-03-29 at 22:10 -0400, Mimi Zohar wrote:
> Hi Roberto,
>
> On Sat, 2020-03-28 at 11:18 +0000, Roberto Sassu wrote:
> > Hi Matthew, Mimi
> >
> > I have a question about portable signatures. Is there any particular reason
> > why a write to a file is not denied by IMA if metadata are immutable?
>
> As much as possible, IMA and EVM should be independent of each other.
> EVM is responsible for the integrity of file metadata, so it needs to
> read other security xattrs, but IMA shouldn't be looking at the EVM
> xattr.
>
> Like any other security xattr, responsibility for maintaining the
> xattr is left up to the particular LSM. In this case, EVM would need
> to prevent the file from being opened rw. Should that be hard coded
> or based on an EVM policy?
Thinking about this a bit more, evm_verifyxattr() is already returning
INTEGRITY_PASS_IMMUTABLE. I guess IMA could make decisions based on
it.
Mimi
next prev parent reply other threads:[~2020-03-30 15:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-28 11:18 Immutable metadata Roberto Sassu
2020-03-30 2:10 ` Mimi Zohar
2020-03-30 15:46 ` Mimi Zohar [this message]
2020-03-30 15:56 ` Roberto Sassu
2020-03-30 18:36 ` Mimi Zohar
2020-03-31 6:56 ` Roberto Sassu
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