From nobody Sun Dec 14 12:12:44 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 B1F67161302 for ; Sat, 19 Apr 2025 15:04:36 +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=1745075078; cv=none; b=GHp4/dvcVk4p56R99TqwL2PDzdcQsIjQ32KTntnlnlFM61+9jrEUsyOKzS9g0+Vt7HH4gIPLgurwHYir4CcoaM7+HjBLLxLRPFvvUp7E7BztyZ0CDfi4FzO486oS7R7DV2GuUzlIZkXXj8zLA0T1hLquh7MbxJtoFdhatryEc5g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745075078; c=relaxed/simple; bh=KT6+zD1kiIB+LKQqAB5iiWkSwIi/9XAVFeUDVvZIFHs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=bdTsw5/pT6zYJjEtcWvQYHJIezzrVLAAJXzWa/TlvI+OW3QL6iq+r0ODsgEvjhoMfS/0W5X4eq1U0IhP5WBouJybScQ6VJ+/9p/KmuxJnuvTOyDPnd+k3UYZaCXfdDEhzpzNo3oRSzpDZUSWXwS+y+p3/3skHb2WKST54FB7G9k= 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=G38WiR+H; 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="G38WiR+H" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745075075; 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=B2b52dp/7QUNWm70nZpu4N1OWTh6Lfw+QpUQkzTr6A8=; b=G38WiR+HPKZEIGWpXXE99PJe6KcIy27qqh+wsM0gf6vgOLfjf7qUPRO2NT1HROmbhmzg1U WR0wUwUiulCGadiHcJeTDmgadZqCOm4wIhOapWw+W7wcZkTVcR/oIzrIOmlDmYM2TxJd1j 1ZsuDTUFtr/tQVpaxuK7jc/AYOQMj7I= Received: from mx-prod-mc-02.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-553-88CWU5ZEMc6C5IuROEeZyA-1; Sat, 19 Apr 2025 11:04:31 -0400 X-MC-Unique: 88CWU5ZEMc6C5IuROEeZyA-1 X-Mimecast-MFC-AGG-ID: 88CWU5ZEMc6C5IuROEeZyA_1745075071 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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DC7CE1956086; Sat, 19 Apr 2025 15:04:30 +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 6B063180175B; Sat, 19 Apr 2025 15:04:29 +0000 (UTC) From: Joel Savitz To: linux-kernel@vger.kernel.org Cc: Joel Savitz , Jonathan Corbet , linux-doc@vger.kernel.org Subject: [PATCH v2] docs: namespace: Tweak and reword resource control doc Date: Sat, 19 Apr 2025 11:04:28 -0400 Message-ID: <20250419150428.1129352-1-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 --- Changes since v1: - Fix spelling of resource .../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..350134c26a98 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 resource 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