From: Daniel Borkmann <daniel@iogearbox.net>
To: KP Singh <kpsingh@kernel.org>, Song Liu <song@kernel.org>
Cc: Yafang Shao <laoar.shao@gmail.com>,
ast@kernel.org, john.fastabend@gmail.com, andrii@kernel.org,
martin.lau@linux.dev, yonghong.song@linux.dev, sdf@google.com,
haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org,
Luis Gerhorst <gerhorst@cs.fau.de>
Subject: Re: [PATCH bpf-next] bpf: Inherit system settings for CPU security mitigations
Date: Fri, 6 Oct 2023 18:55:03 +0200 [thread overview]
Message-ID: <a3ad62c3-c523-fc40-fc4c-1197c34b79b9@iogearbox.net> (raw)
In-Reply-To: <CACYkzJ7Yq4QXnosqVTAtfqssUiG_+rsHouy=-iwTOZd5oEXgBg@mail.gmail.com>
On 10/6/23 1:30 AM, KP Singh wrote:
> On Thu, Oct 5, 2023 at 8:02 PM Song Liu <song@kernel.org> wrote:
>> On Thu, Oct 5, 2023 at 1:41 AM Yafang Shao <laoar.shao@gmail.com> wrote:
>>>
>>> Currently, there exists a system-wide setting related to CPU security
>>> mitigations, denoted as 'mitigations='. When set to 'mitigations=off', it
>>> deactivates all optional CPU mitigations. Therefore, if we implement a
>>> system-wide 'mitigations=off' setting, it should inherently bypass Spectre
>>> v1 and Spectre v4 in the BPF subsystem.
>>>
>>> Please note that there is also a 'nospectre_v1' setting on x86 and ppc
>>> architectures, though it is not currently exported. For the time being,
>>> let's disregard it.
From reading, the cpu_mitigations_off() is a more generic toggle to turn these
generally off, so going via cpu_mitigations_off() is fine in our case and does
not leave some corner cases behind. I presume you mean above that in future the
BPF side could respect some more fine-tuned settings, though it probably might
need some more coordination wrt archs to abstract sth generic out of it.
>>> This idea emerged during our discussion about potential Spectre v1 attacks
>>> with Luis[1].
>>>
>>> [1]. https://lore.kernel.org/bpf/b4fc15f7-b204-767e-ebb9-fdb4233961fb@iogearbox.net/
>>>
>>> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
>>> Cc: Luis Gerhorst <gerhorst@cs.fau.de>
>>
>> Acked-by: Song Liu <song@kernel.org>
>>
>
> Acked-by: KP Singh <kpsingh@kernel.org>
Thanks,
Daniel
next prev parent reply other threads:[~2023-10-06 16:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 8:41 [PATCH bpf-next] bpf: Inherit system settings for CPU security mitigations Yafang Shao
2023-10-05 17:24 ` Stanislav Fomichev
2023-10-05 18:01 ` Song Liu
2023-10-05 23:30 ` KP Singh
2023-10-06 16:55 ` Daniel Borkmann [this message]
2023-10-06 18:20 ` patchwork-bot+netdevbpf
2023-10-11 22:53 ` Andrii Nakryiko
2023-10-12 2:29 ` Yafang Shao
2023-10-12 4:42 ` Andrii Nakryiko
2023-10-20 0:42 ` Alexei Starovoitov
2023-10-20 2:35 ` Yafang Shao
2023-10-22 9:26 ` [PATCH bpf-next] selftests/bpf: Fix selftests broken by mitigations=off Yafang Shao
2023-10-22 9:49 ` [PATCH v2 " Yafang Shao
2023-10-22 10:05 ` Yafang Shao
2023-10-25 3:11 ` [PATCH v3 " Yafang Shao
2023-10-25 4:56 ` Yonghong Song
2023-10-26 13:46 ` Daniel Borkmann
2023-10-26 16:54 ` Yonghong Song
2023-10-26 13:50 ` patchwork-bot+netdevbpf
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