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tmpfiles: introduce the concept of unsafe operations

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Various operations done by systemd-tmpfiles may only be safely done at
boot (e.g. removal of X lockfiles in /tmp, creation of /run/nologin).
Other operations may be done at any point in time (e.g. setting the
ownership on /{run,var}/log/journal). This distinction is largely
orthogonal to the type of operation.

A new switch --unsafe is added, and operations which should only be
executed during bootup are marked with an exclamation mark in the
configuration files. systemd-tmpfiles.service is modified to use this
switch, and guards are added so it is hard to re-start it by mistake.

If we install a new version of systemd, we actually want to enforce
some changes to tmpfiles configuration immediately. This should now be
possible to do safely, so distribution packages can be modified to
execute the "safe" subset at package installation time.

/run/nologin creation is split out into a separate service, to make it
easy to override.

https://bugzilla.redhat.com/show_bug.cgi?id=1043212
https://bugzilla.redhat.com/show_bug.cgi?id=1045849
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2013-12-20 20:25:39 -05:00
parent ef72c1f06e
commit c4708f1323
9 changed files with 71 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
Makefile.am
View File

@ -1584,6 +1584,7 @@ nodist_systemunit_DATA += \
dist_tmpfiles_DATA = \
tmpfiles.d/systemd.conf \
tmpfiles.d/systemd-nologin.conf \
tmpfiles.d/tmp.conf \
tmpfiles.d/x11.conf

6
man/systemd-tmpfiles.xml
View File

@ -146,6 +146,12 @@
configuration files are
removed.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--unsafe</option></term>
<listitem><para>Also execute lines
with an exclamation mark.
</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--prefix=PATH</option></term>
<listitem><para>Only apply rules that

25
man/tmpfiles.d.xml
View File

@ -113,6 +113,9 @@ L /tmp/foobar - - - - /dev/null</programlisting>
<refsect2>
<title>Type</title>
<para>The type consists of a single letter and
optionally an exclamation mark.</para>
<para>The following line types are understood:</para>
<variablelist>
@ -262,6 +265,28 @@ L /tmp/foobar - - - - /dev/null</programlisting>
names.</para></listitem>
</varlistentry>
</variablelist>
<para>If the exclamation mark is used, this
line is only safe of execute during boot, and
can break a running system. Lines without the
exclamation mark are presumed to be safe to
execute at any time, e.g. on package upgrades.
<command>systemd-tmpfiles</command> will
execute line with an exclamation mark only if
option <option>--unsafe</option> is given.
</para>
<para>For example:
<programlisting>
# Make sure these are created by default so that nobody else can
d /tmp/.X11-unix 1777 root root 10d
# Unlink the X11 lock files
r! /tmp/.X[0-9]*-lock
</programlisting>
The second line in contrast to the first one
would break a running system, and will only be
executed with <option>--unsafe</option>.</para>
</refsect2>
<refsect2>

22
src/tmpfiles/tmpfiles.c
View File

@ -107,6 +107,7 @@ static Set *unix_sockets = NULL;
static bool arg_create = false;
static bool arg_clean = false;
static bool arg_remove = false;
static bool arg_unsafe = false;
static char **include_prefixes = NULL;
static char **exclude_prefixes = NULL;
@ -1077,7 +1078,7 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
_cleanup_item_free_ Item *i = NULL;
Item *existing;
_cleanup_free_ char
*mode = NULL, *user = NULL, *group = NULL, *age = NULL, *path = NULL;
*action = NULL, *mode = NULL, *user = NULL, *group = NULL, *age = NULL, *path = NULL;
char type;
Hashmap *h;
int r, n = -1;
@ -1087,8 +1088,8 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
assert(buffer);
r = sscanf(buffer,
"%c %ms %ms %ms %ms %ms %n",
&type,
"%ms %ms %ms %ms %ms %ms %n",
&action,
&path,
&mode,
&user,
@ -1100,6 +1101,14 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
return -EIO;
}
if (strlen(action) > 2 || (strlen(action) > 1 && action[1] != '!')) {
log_error("[%s:%u] Unknown modifier '%s'", fname, line, action);
return -EINVAL;
} else if (strlen(action) > 1 && !arg_unsafe)
return 0;
type = action[0];
i = new0(Item, 1);
if (!i)
return log_oom();
@ -1271,6 +1280,7 @@ static int help(void) {
" --create Create marked files/directories\n"
" --clean Clean up marked directories\n"
" --remove Remove marked files/directories\n"
" --unsafe Execute actions only safe at boot\n"
" --prefix=PATH Only apply rules that apply to paths with the specified prefix\n"
" --exclude-prefix=PATH Ignore rules that apply to paths with the specified prefix\n",
program_invocation_short_name);
@ -1285,6 +1295,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_CREATE,
ARG_CLEAN,
ARG_REMOVE,
ARG_UNSAFE,
ARG_PREFIX,
ARG_EXCLUDE_PREFIX,
};
@ -1295,6 +1306,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "create", no_argument, NULL, ARG_CREATE },
{ "clean", no_argument, NULL, ARG_CLEAN },
{ "remove", no_argument, NULL, ARG_REMOVE },
{ "unsafe", no_argument, NULL, ARG_UNSAFE },
{ "prefix", required_argument, NULL, ARG_PREFIX },
{ "exclude-prefix", required_argument, NULL, ARG_EXCLUDE_PREFIX },
{}
@ -1329,6 +1341,10 @@ static int parse_argv(int argc, char *argv[]) {
arg_remove = true;
break;
case ARG_UNSAFE:
arg_unsafe = true;
break;
case ARG_PREFIX:
if (strv_extend(&include_prefixes, optarg) < 0)
return log_oom();

6
tmpfiles.d/legacy.conf
View File

@ -29,6 +29,6 @@ d /run/lock/lockdev 0775 root lock -
# kernel command line options 'fsck.mode=force', 'fsck.mode=skip' and
# 'quotacheck.mode=force'
r /forcefsck
r /fastboot
r /forcequotacheck
r! /forcefsck
r! /fastboot
r! /forcequotacheck

11
tmpfiles.d/systemd-nologin.conf Normal file
View File

@ -0,0 +1,11 @@
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
# See tmpfiles.d(5) and systemd-forbid-user-logins.service(5).
# This file has special suffix so it is not run by mistake.
F! /run/nologin 0644 - - - "System is booting up. See pam_nologin(8)"

4
tmpfiles.d/systemd.conf
View File

@ -8,7 +8,7 @@
# See tmpfiles.d(5) for details
d /run/user 0755 root root ~10d
F /run/utmp 0664 root utmp -
F! /run/utmp 0664 root utmp -
f /var/log/wtmp 0664 root utmp -
f /var/log/btmp 0600 root utmp -
@ -22,8 +22,6 @@ d /run/systemd/users 0755 root root -
d /run/systemd/machines 0755 root root -
d /run/systemd/shutdown 0755 root root -
F /run/nologin 0644 - - - "System is booting up. See pam_nologin(8)"
m /var/log/journal 2755 root systemd-journal - -
m /var/log/journal/%m 2755 root systemd-journal - -
m /run/log/journal 2755 root systemd-journal - -

2
tmpfiles.d/x11.conf
View File

@ -15,4 +15,4 @@ d /tmp/.font-unix 1777 root root 10d
d /tmp/.Test-unix 1777 root root 10d
# Unlink the X11 lock files
r /tmp/.X[0-9]*-lock
r! /tmp/.X[0-9]*-lock

6
units/systemd-tmpfiles-setup.service.in
View File

@ -6,7 +6,7 @@
# (at your option) any later version.
[Unit]
Description=Recreate Volatile Files and Directories
Description=Create Volatile Files and Directories
Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
DefaultDependencies=no
Wants=local-fs.target
@ -18,8 +18,10 @@ ConditionDirectoryNotEmpty=|/lib/tmpfiles.d
ConditionDirectoryNotEmpty=|/usr/local/lib/tmpfiles.d
ConditionDirectoryNotEmpty=|/etc/tmpfiles.d
ConditionDirectoryNotEmpty=|/run/tmpfiles.d
RefuseManualStart=yes
RefuseManualStop=yes
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=@rootbindir@/systemd-tmpfiles --create --remove --exclude-prefix=/dev
ExecStart=@rootbindir@/systemd-tmpfiles --create --remove --unsafe --exclude-prefix=/dev