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authorLennart Poettering <lennart@poettering.net>2016-08-25 15:57:21 +0200
committerDjalal Harouni <tixxdz@opendz.org>2016-09-25 10:42:18 +0200
commit3f815163ff8fdcdbd329680580df36f94e15325d (patch)
tree1436ba9f8a74ad8c6f4311764b7591a8283a5c00 /man/systemd.exec.xml
parent160cfdbed3eb23b6bc3c17613685b756f23be4a1 (diff)
core: introduce ProtectSystem=strict
Let's tighten our sandbox a bit more: with this change ProtectSystem= gains a new setting "strict". If set, the entire directory tree of the system is mounted read-only, but the API file systems /proc, /dev, /sys are excluded (they may be managed with PrivateDevices= and ProtectKernelTunables=). Also, /home and /root are excluded as those are left for ProtectHome= to manage. In this mode, all "real" file systems (i.e. non-API file systems) are mounted read-only, and specific directories may only be excluded via ReadWriteDirectories=, thus implementing an effective whitelist instead of blacklist of writable directories. While we are at, also add /efi to the list of paths always affected by ProtectSystem=. This is a follow-up for b52a109ad38cd37b660ccd5394ff5c171a5e5355 which added /efi as alternative for /boot. Our namespacing logic should respect that too.
Diffstat (limited to 'man/systemd.exec.xml')
-rw-r--r--man/systemd.exec.xml33
1 files changed, 17 insertions, 16 deletions
diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml
index 07128b489e..1b672fe0c9 100644
--- a/man/systemd.exec.xml
+++ b/man/systemd.exec.xml
@@ -1020,22 +1020,23 @@
<varlistentry>
<term><varname>ProtectSystem=</varname></term>
- <listitem><para>Takes a boolean argument or
- <literal>full</literal>. If true, mounts the
- <filename>/usr</filename> and <filename>/boot</filename>
- directories read-only for processes invoked by this unit. If
- set to <literal>full</literal>, the <filename>/etc</filename>
- directory is mounted read-only, too. This setting ensures that
- any modification of the vendor-supplied operating system (and
- optionally its configuration) is prohibited for the service.
- It is recommended to enable this setting for all long-running
- services, unless they are involved with system updates or need
- to modify the operating system in other ways. Note however
- that processes retaining the CAP_SYS_ADMIN capability can undo
- the effect of this setting. This setting is hence particularly
- useful for daemons which have this capability removed, for
- example with <varname>CapabilityBoundingSet=</varname>.
- Defaults to off.</para></listitem>
+ <listitem><para>Takes a boolean argument or the special values <literal>full</literal> or
+ <literal>strict</literal>. If true, mounts the <filename>/usr</filename> and <filename>/boot</filename>
+ directories read-only for processes invoked by this unit. If set to <literal>full</literal>, the
+ <filename>/etc</filename> directory is mounted read-only, too. If set to <literal>strict</literal> the entire
+ file system hierarchy is mounted read-only, except for the API file system subtrees <filename>/dev</filename>,
+ <filename>/proc</filename> and <filename>/sys</filename> (protect these directories using
+ <varname>PrivateDevices=</varname>, <varname>ProtectKernelTunables=</varname>,
+ <varname>ProtectControlGroups=</varname>). This setting ensures that any modification of the vendor-supplied
+ operating system (and optionally its configuration, and local mounts) is prohibited for the service. It is
+ recommended to enable this setting for all long-running services, unless they are involved with system updates
+ or need to modify the operating system in other ways. If this option is used,
+ <varname>ReadWritePaths=</varname> may be used to exclude specific directories from being made read-only. Note
+ that processes retaining the <constant>CAP_SYS_ADMIN</constant> capability (and with no system call filter that
+ prohibits mount-related system calls applied) can undo the effect of this setting. This setting is hence
+ particularly useful for daemons which have this either the <literal>@mount</literal> set filtered using
+ <varname>SystemCallFilter=</varname>, or have the <constant>CAP_SYS_ADMIN</constant> capability removed, for
+ example with <varname>CapabilityBoundingSet=</varname>. Defaults to off.</para></listitem>
</varlistentry>
<varlistentry>