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Subject: Re: [RFC PATCH v8 0/3] Add support for AT_INTERPRETED (was O_MAYEXEC)
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     linux-kernel@vger.kernel.org, Aleksa Sarai <cyphar@cyphar.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Christian Heimes <christian@python.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Deven Bowers <deven.desai@linux.microsoft.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Eric Chiang <ericchiang@google.com>,
        Florian Weimer <fweimer@redhat.com>,
        James Morris <jmorris@namei.org>, Jan Kara <jack@suse.cz>,
        Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        Matthew Garrett <mjg59@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Miklos Szeredi <mszeredi@redhat.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        =?UTF-8?Q?Philippe_Tr=c3=a9buchet?= 
        <philippe.trebuchet@ssi.gouv.fr>,
        Scott Shell <scottsh@microsoft.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Shuah Khan <shuah@kernel.org>,
        Steve Dower <steve.dower@python.org>,
        Steve Grubb <sgrubb@redhat.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Thibaut Sautereau <thibaut.sautereau@clip-os.org>,
        Vincent Strubel <vincent.strubel@ssi.gouv.fr>,
        kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
        linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
References: <20200908075956.1069018-1-mic@digikod.net>
 <20200908185026.GU1236603@ZenIV.linux.org.uk>
From:   =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= <mic@digikod.net>
Message-ID: <e3223b50-0d00-3b64-1e09-cfb1b9648b02@digikod.net>
Date:   Wed, 9 Sep 2020 09:19:11 +0200
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On 08/09/2020 20:50, Al Viro wrote:
> On Tue, Sep 08, 2020 at 09:59:53AM +0200, Micka?l Sala?n wrote:
>> Hi,
>>
>> This height patch series rework the previous O_MAYEXEC series by not
>> adding a new flag to openat2(2) but to faccessat2(2) instead.  As
>> suggested, this enables to perform the access check on a file descriptor
>> instead of on a file path (while opening it).  This may require two
>> checks (one on open and then with faccessat2) but it is a more generic
>> approach [8].
> 
> Again, why is that folded into lookup/open/whatnot, rather than being
> an operation applied to a file (e.g. O_PATH one)?
> 

I don't understand your question. AT_INTERPRETED can and should be used
with AT_EMPTY_PATH. The two checks I wrote about was for IMA.