From: Kees Cook <keescook@chromium.org>
To: "Mickaël Salaün" <mic@digikod.net>
Cc: linux-kernel@vger.kernel.org, "Aleksa Sarai" <cyphar@cyphar.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Andy Lutomirski" <luto@kernel.org>,
"Christian Heimes" <christian@python.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Deven Bowers" <deven.desai@linux.microsoft.com>,
"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>,
"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>,
"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 v5 2/6] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount property
Date: Tue, 12 May 2020 14:09:41 -0700 [thread overview]
Message-ID: <202005121407.A339D31A@keescook> (raw)
In-Reply-To: <20200505153156.925111-3-mic@digikod.net>
On Tue, May 05, 2020 at 05:31:52PM +0200, Mickaël Salaün wrote:
> This new MAY_EXECMOUNT flag enables to check if the underlying mount
> point of an inode is marked as executable. This is useful to implement
> a security policy taking advantage of the noexec mount option.
>
> This flag is set according to path_noexec(), which checks if a mount
> point is mounted with MNT_NOEXEC or if the underlying superblock is
> SB_I_NOEXEC.
>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> Reviewed-by: Philippe Trébuchet <philippe.trebuchet@ssi.gouv.fr>
> Reviewed-by: Thibaut Sautereau <thibaut.sautereau@ssi.gouv.fr>
> Cc: Aleksa Sarai <cyphar@cyphar.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Kees Cook <keescook@chromium.org>
> ---
> fs/namei.c | 2 ++
> include/linux/fs.h | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index a320371899cf..33b6d372e74a 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -2849,6 +2849,8 @@ static int may_open(const struct path *path, int acc_mode, int flag)
> break;
> }
>
> + /* Pass the mount point executability. */
> + acc_mode |= path_noexec(path) ? 0 : MAY_EXECMOUNT;
> error = inode_permission(inode, MAY_OPEN | acc_mode);
> if (error)
> return error;
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 313c934de9ee..79435fca6c3e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -103,6 +103,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
> #define MAY_NOT_BLOCK 0x00000080
> /* the inode is opened with O_MAYEXEC */
> #define MAY_OPENEXEC 0x00000100
> +/* the mount point is marked as executable */
> +#define MAY_EXECMOUNT 0x00000200
>
> /*
> * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
I find this name unintuitive, but I cannot think of anything better,
since I think my problem is that "MAY" doesn't map to the language I
want to use to describe what this flag is indicating.
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2020-05-12 21:10 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 [this message]
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
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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