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Message-ID: <202005132002.91B8B63@keescook>
Date: Wed, 13 May 2020 20:05:09 -0700
From: Kees Cook <keescook@...omium.org>
To: Stephen Smalley <stephen.smalley.work@...il.com>
Cc: Mickaël Salaün <mic@...ikod.net>,
linux-kernel <linux-kernel@...r.kernel.org>,
Aleksa Sarai <cyphar@...har.com>,
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Daniel Borkmann <daniel@...earbox.net>,
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Shuah Khan <shuah@...nel.org>, Steve Dower <steve.dower@...hon.org>,
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Thibaut Sautereau <thibaut.sautereau@....gouv.fr>,
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Linux FS Devel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec
through O_MAYEXEC
On Wed, May 13, 2020 at 04:27:39PM -0700, Kees Cook wrote:
> Like, couldn't just the entire thing just be:
>
> diff --git a/fs/namei.c b/fs/namei.c
> index a320371899cf..0ab18e19f5da 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -2849,6 +2849,13 @@ static int may_open(const struct path *path, int acc_mode, int flag)
> break;
> }
>
> + if (unlikely(mask & MAY_OPENEXEC)) {
> + if (sysctl_omayexec_enforce & OMAYEXEC_ENFORCE_MOUNT &&
> + path_noexec(path))
> + return -EACCES;
> + if (sysctl_omayexec_enforce & OMAYEXEC_ENFORCE_FILE)
> + acc_mode |= MAY_EXEC;
> + }
> error = inode_permission(inode, MAY_OPEN | acc_mode);
> if (error)
> return error;
>
FYI, I've confirmed this now. Effectively with patch 2 dropped, patch 3
reduced to this plus the Kconfig and sysctl changes, the self tests
pass.
I think this makes things much cleaner and correct.
--
Kees Cook
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