From nobody Sun Dec 14 12:12:42 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06AC721127E for ; Fri, 18 Apr 2025 15:29:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744990163; cv=none; b=pbQdd07tM5JURQrVn/O4TB9Irfxm/bl0KanCCNXqDnHVZPwRt+tRuE57qqMXyH4JnecAIBAQUIlGvKZkseK04rl43rEXKyBdTbBiY0vooPWYEpPu5QiRHJnWT7YpmGNx5ipBuXVM3dX1eVDZft+7iA5OqClH5jsACkdnAMLting= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744990163; c=relaxed/simple; bh=yhg61Z5FgdpTqeKa66MzWE8kZ0brp5lJvNYoMhx0bKU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=oFJIBpN9MqNHBDKyGj/rfL/B8Y1/qY8tfR+P4GhnWG8y6s4IiF97c9HBixA5ZsBZeB6DRDevOGjXbyX4T3N077Kg9OIHpup/TTPcfVek+0Z8pWMyLbUPqpp7q/pI+uF2oIJSnUjsLDHbn4AAxRW8mEpI64+koIvjCXuyvVz2Hps= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=TjsiZXHJ; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TjsiZXHJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744990160; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=EBkbeEOM4+zmvVxiJ3s2YnpGyrudvKTNT92Qch4FMKk=; b=TjsiZXHJjCGE9Oj/7/rI43hvr7Jf2F2AZVHMUqnliWCbn95EHtwexMaa5zN9wcarZOmaS1 gmkI8bXiATEJCkBWr6zaaX+0RrRbeaOvX0aLH4l5qzb289MPClj5tBMQXwx6s01upq7fgG OtQlcnGcOsd2FN5p0PtZ+llUbGIDJVk= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-395-osmMWsiJPxWyysTSjw8FUw-1; Fri, 18 Apr 2025 11:29:17 -0400 X-MC-Unique: osmMWsiJPxWyysTSjw8FUw-1 X-Mimecast-MFC-AGG-ID: osmMWsiJPxWyysTSjw8FUw_1744990156 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 789031956088; Fri, 18 Apr 2025 15:29:16 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.89.24]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 77CBC1800965; Fri, 18 Apr 2025 15:29:15 +0000 (UTC) From: Joel Savitz To: linux-kernel@vger.kernel.org Cc: Joel Savitz , Jonathan Corbet , linux-doc@vger.kernel.org Subject: [PATCH] docs: namespace: Tweak and reword resource control doc Date: Fri, 18 Apr 2025 11:29:10 -0400 Message-ID: <20250418152910.1121670-1-jsavitz@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Content-Type: text/plain; charset="utf-8" Fix the document title and reword the phrasing to active voice. Signed-off-by: Joel Savitz --- .../namespaces/resource-control.rst | 24 +++++++++---------- 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/Documentation/admin-guide/namespaces/resource-control.rst b/Do= cumentation/admin-guide/namespaces/resource-control.rst index 369556e00f0c..624f4dceea46 100644 --- a/Documentation/admin-guide/namespaces/resource-control.rst +++ b/Documentation/admin-guide/namespaces/resource-control.rst @@ -1,17 +1,17 @@ -=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D -Namespaces research control -=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +User namespaces and resoruce control +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 -There are a lot of kinds of objects in the kernel that don't have -individual limits or that have limits that are ineffective when a set -of processes is allowed to switch user ids. With user namespaces -enabled in a kernel for people who don't trust their users or their -users programs to play nice this problems becomes more acute. +The kernel contains many kinds of objects that either don't have +individual limits or that have limits which are ineffective when +a set of processes is allowed to switch their UID. On a system +where there admins don't trust their users or their users' programs, +user namespaces expose the system to potential misuse of resources. =20 -Therefore it is recommended that memory control groups be enabled in -kernels that enable user namespaces, and it is further recommended -that userspace configure memory control groups to limit how much -memory user's they don't trust to play nice can use. +In order to mitigate this, we recommend that admins enable memory +control groups on any system that enables user namespaces. +Furthermore, we recommend that admins configure the memory control +groups to limit the maximum memory usable by any untrusted user. =20 Memory control groups can be configured by installing the libcgroup package present on most distros editing /etc/cgrules.conf, --=20 2.45.2