linux-kernel - Re: [RFC PATCH v1 0/5] Add support for O

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Date:   Thu, 13 Dec 2018 07:16:52 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Florian Weimer <fweimer@...hat.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Mickaël Salaün <mic@...ikod.net>,
        linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        James Morris <jmorris@...ei.org>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Matthew Garrett <mjg59@...gle.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Mickaël Salaün <mickael.salaun@....gouv.fr>,
        Philippe Trébuchet 
        <philippe.trebuchet@....gouv.fr>, Shuah Khan <shuah@...nel.org>,
        Thibaut Sautereau <thibaut.sautereau@....gouv.fr>,
        Vincent Strubel <vincent.strubel@....gouv.fr>,
        Yves-Alexis Perez <yves-alexis.perez@....gouv.fr>,
        kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        linux-integrity <linux-integrity@...r.kernel.org>
Subject: Re: [RFC PATCH v1 0/5] Add support for O_MAYEXEC

[Cc'ing linux-integrity]

On Thu, 2018-12-13 at 12:26 +0100, Florian Weimer wrote:
> * Mimi Zohar:
> 
> > The indication needs to be set during file open, before the open
> > returns to the caller.  This is the point where ima_file_check()
> > verifies the file's signature.  On failure, access to the file is
> > denied.
> 
> Does this verification happen for open with O_PATH?

Interesting!  According to the manpage, userspace cannot read/write to
the file.  It looks like do_o_path() intentionally skips do_last(),
with the call to ima_file_check().  If the file data isn't being
accessed, does the file's integrity need to be verified?

Mimi