From: Christian Brauner <christian.brauner@ubuntu.com>
To: Kees Cook <keescook@chromium.org>
Cc: luto@amacapital.net, jannh@google.com, wad@chromium.org,
shuah@kernel.org, ast@kernel.org, daniel@iogearbox.net,
kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Tycho Andersen <tycho@tycho.ws>,
Tyler Hicks <tyhicks@canonical.com>
Subject: Re: [PATCH v2 1/3] seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE
Date: Fri, 11 Oct 2019 11:46:14 +0200 [thread overview]
Message-ID: <20191011094613.rs45knchjbe7edv4@wittgenstein> (raw)
In-Reply-To: <201910101440.17A13952@keescook>
On Thu, Oct 10, 2019 at 02:45:38PM -0700, Kees Cook wrote:
> On Fri, Sep 20, 2019 at 10:30:05AM +0200, Christian Brauner wrote:
> > + * Similar precautions should be applied when stacking SECCOMP_RET_USER_NOTIF.
> > + * For SECCOMP_RET_USER_NOTIF filters acting on the same syscall the uppermost
> > + * filter takes precedence. This means that the uppermost
> > + * SECCOMP_RET_USER_NOTIF filter can override any SECCOMP_IOCTL_NOTIF_SEND from
> > + * lower filters essentially allowing all syscalls to pass by using
> > + * SECCOMP_USER_NOTIF_FLAG_CONTINUE. Note that SECCOMP_RET_USER_NOTIF can
> ^^^^^^^^^^^^^^
> This is meant to read RET_TRACE, yes?
Yes. :)
>
> > + * equally be overriden by SECCOMP_USER_NOTIF_FLAG_CONTINUE.
>
> I rewrote this paragraph with that corrected and swapping some
> "upper/lower" to "most recently added" etc:
>
> + * Similar precautions should be applied when stacking SECCOMP_RET_USER_NOTIF
> + * or SECCOMP_RET_TRACE. For SECCOMP_RET_USER_NOTIF filters acting on the
> + * same syscall, the most recently added filter takes precedence. This means
> + * that the new SECCOMP_RET_USER_NOTIF filter can override any
> + * SECCOMP_IOCTL_NOTIF_SEND from earlier filters, essentially allowing all
> + * such filtered syscalls to be executed by sending the response
> + * SECCOMP_USER_NOTIF_FLAG_CONTINUE. Note that SECCOMP_RET_TRACE can equally
> + * be overriden by SECCOMP_USER_NOTIF_FLAG_CONTINUE.
>
>
> Ultimately, I think this caveat is fine. RET_USER_NOTIF and RET_TRACE are
> both used from the "process manager" use-case. The benefits of "continue"
> semantics here outweighs the RET_USER_NOTIF and RET_TRACE "bypass". If
> we end up in a situation where we need to deal with some kind of
> nesting where this is a problem in practice, we can revisit this.
>
> Applied to my for-next/seccomp. Thanks!
Thanks!
Christian
next prev parent reply other threads:[~2019-10-11 9:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 8:30 [PATCH v2 0/3] seccomp: continue syscall from notifier Christian Brauner
2019-09-20 8:30 ` [PATCH v2 1/3] seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE Christian Brauner
2019-10-10 21:45 ` Kees Cook
2019-10-11 9:46 ` Christian Brauner [this message]
2019-09-20 8:30 ` [PATCH v2 2/3] seccomp: avoid overflow in implicit constant conversion Christian Brauner
2019-09-20 8:47 ` Tycho Andersen
2019-09-20 8:30 ` [PATCH v2 3/3] seccomp: test SECCOMP_USER_NOTIF_FLAG_CONTINUE Christian Brauner
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