From: Florian Weimer <fweimer@redhat.com>
To: Kees Cook <keescook@chromium.org>
Cc: "Mickaël Salaün" <mic@digikod.net>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Andy Lutomirski" <luto@kernel.org>,
"Mimi Zohar" <zohar@linux.ibm.com>,
"Stephen Smalley" <stephen.smalley.work@gmail.com>,
"Christian Heimes" <christian@python.org>,
"Deven Bowers" <deven.desai@linux.microsoft.com>,
"Tetsuo Handa" <penguin-kernel@I-love.SAKURA.ne.jp>,
"John Johansen" <john.johansen@canonical.com>,
"Kentaro Takeda" <takedakn@nttdata.co.jp>,
"Lev R. Oshvang ." <levonshe@gmail.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Eric Chiang" <ericchiang@google.com>,
"James Morris" <jmorris@namei.org>, "Jan Kara" <jack@suse.cz>,
"Jann Horn" <jannh@google.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Lakshmi Ramasubramanian" <nramas@linux.microsoft.com>,
"Matthew Garrett" <mjg59@google.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Michael Kerrisk" <mtk.manpages@gmail.com>,
"Mickaël Salaün" <mickael.salaun@ssi.gouv.fr>,
"Philippe Trébuchet" <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>,
"Thibaut Sautereau" <thibaut.sautereau@ssi.gouv.fr>,
"Vincent Strubel" <vincent.strubel@ssi.gouv.fr>,
linux-kernel <linux-kernel@vger.kernel.org>,
kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
linux-integrity@vger.kernel.org,
"LSM List" <linux-security-module@vger.kernel.org>,
"Linux FS Devel" <linux-fsdevel@vger.kernel.org>
Subject: Re: How about just O_EXEC? (was Re: [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC)
Date: Fri, 15 May 2020 16:43:37 +0200 [thread overview]
Message-ID: <87r1vluuli.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <202005150732.17C5EE0@keescook> (Kees Cook's message of "Fri, 15 May 2020 07:37:16 -0700")
* Kees Cook:
> On Fri, May 15, 2020 at 10:43:34AM +0200, Florian Weimer wrote:
>> * Kees Cook:
>>
>> > Maybe I've missed some earlier discussion that ruled this out, but I
>> > couldn't find it: let's just add O_EXEC and be done with it. It actually
>> > makes the execve() path more like openat2() and is much cleaner after
>> > a little refactoring. Here are the results, though I haven't emailed it
>> > yet since I still want to do some more testing:
>> > https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=kspp/o_exec/v1
>>
>> I think POSIX specifies O_EXEC in such a way that it does not confer
>> read permissions. This seems incompatible with what we are trying to
>> achieve here.
>
> I was trying to retain this behavior, since we already make this
> distinction between execve() and uselib() with the MAY_* flags:
>
> execve():
> struct open_flags open_exec_flags = {
> .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
> .acc_mode = MAY_EXEC,
>
> uselib():
> static const struct open_flags uselib_flags = {
> .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
> .acc_mode = MAY_READ | MAY_EXEC,
>
> I tried to retain this in my proposal, in the O_EXEC does not imply
> MAY_READ:
That doesn't quite parse for me, sorry.
The point is that the script interpreter actually needs to *read* those
files in order to execute them.
Thanks,
Florian
next prev parent reply other threads:[~2020-05-15 14:44 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 15:31 [PATCH v5 0/6] Add support for O_MAYEXEC Mickaël Salaün
2020-05-05 15:31 ` [PATCH v5 1/6] fs: Add support for an O_MAYEXEC flag on openat2(2) Mickaël Salaün
2020-05-12 21:05 ` Kees Cook
2020-05-12 21:40 ` Christian Heimes
2020-05-12 22:56 ` Kees Cook
2020-05-13 10:13 ` Mickaël Salaün
2020-05-05 15:31 ` [PATCH v5 2/6] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount property Mickaël Salaün
2020-05-12 21:09 ` Kees Cook
2020-05-14 8:14 ` Lev R. Oshvang .
2020-05-14 15:48 ` Kees Cook
2020-05-17 16:57 ` Lev R. Oshvang .
2020-05-05 15:31 ` [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC Mickaël Salaün
2020-05-05 15:44 ` Randy Dunlap
2020-05-05 16:55 ` Mickaël Salaün
2020-05-05 17:40 ` Randy Dunlap
2020-05-12 21:48 ` Kees Cook
2020-05-13 11:09 ` Mickaël Salaün
2020-05-13 15:37 ` Stephen Smalley
2020-05-13 23:27 ` Kees Cook
2020-05-14 3:05 ` Kees Cook
2020-05-14 10:12 ` David Laight
2020-05-14 12:22 ` Stephen Smalley
2020-05-14 14:41 ` Kees Cook
2020-05-14 15:52 ` Stephen Smalley
2020-05-14 15:45 ` Kees Cook
2020-05-14 16:10 ` Stephen Smalley
2020-05-14 19:16 ` Mickaël Salaün
2020-05-15 0:58 ` Tetsuo Handa
2020-05-15 8:01 ` How about just O_EXEC? (was Re: [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC) Kees Cook
2020-05-15 8:43 ` Florian Weimer
2020-05-15 14:37 ` Kees Cook
2020-05-15 14:43 ` Florian Weimer [this message]
2020-05-15 15:50 ` Kees Cook
2020-05-18 7:26 ` Florian Weimer
2020-05-19 2:23 ` Aleksa Sarai
2020-05-19 10:13 ` Mickaël Salaün
2020-05-15 11:04 ` Mickaël Salaün
2020-05-15 15:46 ` Kees Cook
2020-05-15 18:24 ` Mickaël Salaün
2020-05-14 19:21 ` [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC Mickaël Salaün
2020-05-05 15:31 ` [PATCH v5 4/6] selftest/openat2: Add tests for O_MAYEXEC enforcing Mickaël Salaün
2020-05-12 21:57 ` Kees Cook
2020-05-13 11:18 ` Mickaël Salaün
2020-05-05 15:31 ` [PATCH v5 5/6] doc: Add documentation for the fs.open_mayexec_enforce sysctl Mickaël Salaün
2020-05-12 22:00 ` Kees Cook
2020-05-13 11:20 ` Mickaël Salaün
2020-05-05 15:31 ` [PATCH v5 6/6] ima: add policy support for the new file open MAY_OPENEXEC flag Mickaël Salaün
2020-05-05 15:36 ` [PATCH v5 0/6] Add support for O_MAYEXEC Mickaël Salaün
2020-05-06 13:58 ` Lev R. Oshvang .
2020-05-06 15:41 ` Aleksa Sarai
2020-05-07 8:30 ` Mickaël Salaün
2020-05-07 8:05 ` David Laight
2020-05-07 8:36 ` Mickaël Salaün
2020-05-07 9:00 ` David Laight
2020-05-07 9:30 ` Mickaël Salaün
2020-05-07 9:44 ` David Laight
2020-05-07 13:38 ` Mickaël Salaün
2020-05-08 7:15 ` Lev R. Oshvang .
2020-05-08 14:01 ` Mimi Zohar
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