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Subject: Re: [RFC PATCH v1 0/5] Add support for O_MAYEXEC
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Florian Weimer <fweimer@redhat.com>
Cc:     Matthew Wilcox <willy@infradead.org>,
        =?ISO-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@digikod.net>,
        linux-kernel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
        James Morris <jmorris@namei.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Matthew Garrett <mjg59@google.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        =?ISO-8859-1?Q?Micka=EBl_Sala=FCn?= <mickael.salaun@ssi.gouv.fr>,
        Philippe =?ISO-8859-1?Q?Tr=E9buchet?= 
        <philippe.trebuchet@ssi.gouv.fr>, Shuah Khan <shuah@kernel.org>,
        Thibaut Sautereau <thibaut.sautereau@ssi.gouv.fr>,
        Vincent Strubel <vincent.strubel@ssi.gouv.fr>,
        Yves-Alexis Perez <yves-alexis.perez@ssi.gouv.fr>,
        kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        linux-integrity <linux-integrity@vger.kernel.org>
Date:   Thu, 13 Dec 2018 07:16:52 -0500
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         <1544699060.6703.11.camel@linux.ibm.com>
         <874lbhoef3.fsf@oldenburg2.str.redhat.com>
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[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