From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B5F8C433F5 for ; Mon, 1 Nov 2021 11:57:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D2C1610CB for ; Mon, 1 Nov 2021 11:57:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232302AbhKAMAR (ORCPT ); Mon, 1 Nov 2021 08:00:17 -0400 Received: from foss.arm.com ([217.140.110.172]:39158 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231693AbhKAMAQ (ORCPT ); Mon, 1 Nov 2021 08:00:16 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 54F23D6E; Mon, 1 Nov 2021 04:57:43 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.81.163]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 153A13F5A1; Mon, 1 Nov 2021 04:57:39 -0700 (PDT) Date: Mon, 1 Nov 2021 11:57:29 +0000 From: Mark Rutland To: Pawan Gupta Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, antonio.gomez.iglesias@intel.com, tony.luck@intel.com, dave.hansen@linux.intel.com, gregkh@linuxfoundation.org, linux@armlinux.org.uk Subject: Re: [PATCH ebpf v3] bpf: Disallow unprivileged bpf by default Message-ID: References: <0ace9ce3f97656d5f62d11093ad7ee81190c3c25.1635535215.git.pawan.kumar.gupta@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0ace9ce3f97656d5f62d11093ad7ee81190c3c25.1635535215.git.pawan.kumar.gupta@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Oct 29, 2021 at 12:43:54PM -0700, Pawan Gupta wrote: > Disabling unprivileged BPF would help prevent unprivileged users from > creating the conditions required for potential speculative execution > side-channel attacks on affected hardware. A deep dive on such attacks > and mitigation is available here [1]. > > Sync with what many distros are currently applying, disable unprivileged > BPF by default. An admin can enable this at runtime, if necessary. > > [1] https://ebpf.io/summit-2021-slides/eBPF_Summit_2021-Keynote-Daniel_Borkmann-BPF_and_Spectre.pdf > > Signed-off-by: Pawan Gupta FWIW: Acked-by: Mark Rutland Mark. > --- > v3: > - Drop the conditional default for CONFIG_BPF_UNPRIV_DEFAULT_OFF until > we have an arch generic way to determine arch-common spectre type bugs. > [Mark Rutland, Daniel Borkmann]. > - Also drop the patch to Generalize ARM's CONFIG_CPU_SPECTRE. > - Minor changes to commit message. > > v2: https://lore.kernel.org/lkml/cover.1635383031.git.pawan.kumar.gupta@linux.intel.com/ > - Generalize ARM's CONFIG_CPU_SPECTRE to be available for all architectures. > - Make CONFIG_BPF_UNPRIV_DEFAULT_OFF depend on CONFIG_CPU_SPECTRE. > - Updated commit message to reflect the dependency on CONFIG_CPU_SPECTRE. > - Add reference to BPF spectre presentation in commit message. > > v1: https://lore.kernel.org/all/d37b01e70e65dced2659561ed5bc4b2ed1a50711.1635367330.git.pawan.kumar.gupta@linux.intel.com/ > > kernel/bpf/Kconfig | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig > index a82d6de86522..73d446294455 100644 > --- a/kernel/bpf/Kconfig > +++ b/kernel/bpf/Kconfig > @@ -64,6 +64,7 @@ config BPF_JIT_DEFAULT_ON > > config BPF_UNPRIV_DEFAULT_OFF > bool "Disable unprivileged BPF by default" > + default y > depends on BPF_SYSCALL > help > Disables unprivileged BPF by default by setting the corresponding > @@ -72,6 +73,10 @@ config BPF_UNPRIV_DEFAULT_OFF > disable it by setting it to 1 (from which no other transition to > 0 is possible anymore). > > + Unprivileged BPF can be used to exploit potential speculative > + execution side-channel vulnerabilities on affected hardware. If you > + are concerned about it, answer Y. > + > source "kernel/bpf/preload/Kconfig" > > config BPF_LSM > -- > 2.31.1 >