From: David Laight <David.Laight@ACULAB.COM>
To: "'Alan Cox'" <gnomes@lxorguk.ukuu.org.uk>,
Salvatore Mesoraca <s.mesoraca16@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Kernel Hardening" <kernel-hardening@lists.openwall.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
Solar Designer <solar@openwall.com>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: RE: [PATCH v3 2/2] Protected O_CREAT open in sticky directories
Date: Fri, 24 Nov 2017 10:53:11 +0000 [thread overview]
Message-ID: <33dcc007e92349999ce77bf45825be22@AcuMS.aculab.com> (raw)
In-Reply-To: <20171122165144.07aea7ac@alans-desktop>
From: Alan Cox
> Sent: 22 November 2017 16:52
>
> On Wed, 22 Nov 2017 09:01:46 +0100
> Salvatore Mesoraca <s.mesoraca16@gmail.com> wrote:
>
> > Disallows O_CREAT open missing the O_EXCL flag, in world or
> > group writable directories, even if the file doesn't exist yet.
> > With few exceptions (e.g. shared lock files based on flock())
>
> Enough exceptions to make it a bad idea.
>
> Firstly if you care this much *stop* having shared writable directories.
> We have namespaces, you don't need them. You can give every user their
> own /tmp etc.
Looks like a very bad idea to me as well.
Doesn't this stop all shell redirects into a shared /tmp ?
I'm pretty sure most programs use O_CREAT | O_TRUNC for output
files - they'll all stop working.
If there are some directories where you need to force O_EXCL you
need to make it a property of the directory, not the kernel.
David
next prev parent reply other threads:[~2017-11-24 10:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-22 8:01 [PATCH v3 0/2] Restrict dangerous " Salvatore Mesoraca
2017-11-22 8:01 ` [PATCH v3 1/2] Protected FIFOs and regular files Salvatore Mesoraca
2017-11-23 22:43 ` [kernel-hardening] " Tobin C. Harding
2017-11-24 8:24 ` Salvatore Mesoraca
2017-11-22 8:01 ` [PATCH v3 2/2] Protected O_CREAT open in sticky directories Salvatore Mesoraca
2017-11-22 13:22 ` Matthew Wilcox
2017-11-24 8:29 ` Salvatore Mesoraca
2017-11-22 16:51 ` Alan Cox
2017-11-24 8:31 ` Salvatore Mesoraca
2017-11-24 10:53 ` David Laight [this message]
2017-11-24 11:43 ` Salvatore Mesoraca
2017-11-24 11:53 ` David Laight
2017-11-26 11:29 ` Salvatore Mesoraca
2017-11-27 0:26 ` Solar Designer
2017-11-30 14:39 ` Salvatore Mesoraca
2017-11-30 14:57 ` [kernel-hardening] " Ian Campbell
2017-11-30 16:30 ` [kernel-hardening] " Solar Designer
2017-12-05 10:21 ` Salvatore Mesoraca
2017-12-07 21:47 ` Solar Designer
2017-12-11 12:08 ` Salvatore Mesoraca
2017-11-23 22:57 ` Tobin C. Harding
2017-11-24 8:34 ` Salvatore Mesoraca
2017-11-30 16:53 ` David Laight
2017-11-30 17:51 ` Solar Designer
2017-12-01 9:46 ` David Laight
2017-12-01 15:52 ` Alan Cox
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