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From: "Mickaël Salaün" <mic@digikod.net>
To: Randy Dunlap <rdunlap@infradead.org>, linux-kernel@vger.kernel.org
Cc: "Aleksa Sarai" <cyphar@cyphar.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"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>,
	"Mickaël Salaün" <mickael.salaun@ssi.gouv.fr>,
	"Mimi Zohar" <zohar@linux.ibm.com>,
	"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>,
	"Tetsuo Handa" <penguin-kernel@I-love.SAKURA.ne.jp>,
	"Thibaut Sautereau" <thibaut.sautereau@ssi.gouv.fr>,
	"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
Subject: Re: [PATCH v6 5/7] fs,doc: Enable to enforce noexec mounts or file exec through O_MAYEXEC
Date: Thu, 16 Jul 2020 16:40:56 +0200	[thread overview]
Message-ID: <67fe6c17-a0b3-5c7e-a7c8-4c2b6e0c0592@digikod.net> (raw)
In-Reply-To: <038639b1-92da-13c1-b3e5-8f13639a815e@infradead.org>


On 14/07/2020 20:40, Randy Dunlap wrote:
> Hi,
> 
> On 7/14/20 11:16 AM, Mickaël Salaün wrote:
> 
>> ---
>>  Documentation/admin-guide/sysctl/fs.rst | 45 +++++++++++++++++++++++++
>>  fs/namei.c                              | 29 +++++++++++++---
>>  include/linux/fs.h                      |  1 +
>>  kernel/sysctl.c                         | 12 +++++--
>>  4 files changed, 80 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/sysctl/fs.rst b/Documentation/admin-guide/sysctl/fs.rst
>> index 2a45119e3331..02ec384b8bbf 100644
>> --- a/Documentation/admin-guide/sysctl/fs.rst
>> +++ b/Documentation/admin-guide/sysctl/fs.rst
> 
> Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
> 
> with one tiny nit:
> 
>> @@ -165,6 +166,50 @@ system needs to prune the inode list instead of allocating
>> +The ability to restrict code execution must be thought as a system-wide policy,
>> +which first starts by restricting mount points with the ``noexec`` option.
>> +This option is also automatically applied to special filesystems such as /proc
>> +.  This prevents files on such mount points to be directly executed by the
> 
> Can you move that period from the beginning of the line to the end of the
> previous line?

OK, done. Thanks!

> 
>> +kernel or mapped as executable memory (e.g. libraries).  With script
>> +interpreters using the ``O_MAYEXEC`` flag, the executable permission can then
>> +be checked before reading commands from files. This makes it possible to
>> +enforce the ``noexec`` at the interpreter level, and thus propagates this
>> +security policy to scripts.  To be fully effective, these interpreters also
>> +need to handle the other ways to execute code: command line parameters (e.g.,
>> +option ``-e`` for Perl), module loading (e.g., option ``-m`` for Python),
>> +stdin, file sourcing, environment variables, configuration files, etc.
>> +According to the threat model, it may be acceptable to allow some script
>> +interpreters (e.g. Bash) to interpret commands from stdin, may it be a TTY or a
>> +pipe, because it may not be enough to (directly) perform syscalls.
> 
> thanks.
> 

  reply	other threads:[~2020-07-16 14:41 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-14 18:16 [PATCH v6 0/7] Add support for O_MAYEXEC Mickaël Salaün
2020-07-14 18:16 ` [PATCH v6 1/7] exec: Change uselib(2) IS_SREG() failure to EACCES Mickaël Salaün
2020-07-14 18:16 ` [PATCH v6 2/7] exec: Move S_ISREG() check earlier Mickaël Salaün
2020-07-14 18:16 ` [PATCH v6 3/7] exec: Move path_noexec() " Mickaël Salaün
2020-07-14 18:16 ` [PATCH v6 4/7] fs: Introduce O_MAYEXEC flag for openat2(2) Mickaël Salaün
2020-07-15 20:06   ` Kees Cook
2020-07-16 14:18     ` Mickaël Salaün
2020-07-16 15:31       ` Kees Cook
2020-07-14 18:16 ` [PATCH v6 5/7] fs,doc: Enable to enforce noexec mounts or file exec through O_MAYEXEC Mickaël Salaün
2020-07-14 18:40   ` Randy Dunlap
2020-07-16 14:40     ` Mickaël Salaün [this message]
2020-07-15 20:37   ` Kees Cook
2020-07-16 14:39     ` Mickaël Salaün
2020-07-22 16:16       ` Thibaut Sautereau
2020-07-22 19:04         ` Mickaël Salaün
2020-07-22 19:40           ` Kees Cook
2020-07-14 18:16 ` [PATCH v6 6/7] selftest/openat2: Add tests for O_MAYEXEC enforcing Mickaël Salaün
2020-07-15 20:38   ` Kees Cook
2020-07-14 18:16 ` [PATCH v6 7/7] ima: add policy support for the new file open MAY_OPENEXEC flag Mickaël Salaün
2020-07-15 20:40   ` Kees Cook
2020-07-16 14:40     ` Mickaël Salaün
2020-07-16 14:59       ` Randy Dunlap
2020-07-16 15:22         ` Mickaël Salaün
2020-07-16 19:13         ` Kees Cook
2020-07-16 19:12       ` Kees Cook

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