From 66b1ee20b814b02cd0fb73fec4a2a9b11defc607 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>

Date: Fri, 20 Dec 2013 20:25:39 -0500

Subject: [PATCH] tmpfiles: introduce the concept of unsafe operations

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

---

 Makefile.am                             |  1 +

 man/systemd-tmpfiles.xml                |  6 ++++++

 man/tmpfiles.d.xml                      | 25 +++++++++++++++++++++++++

 src/tmpfiles/tmpfiles.c                 | 22 +++++++++++++++++++---

 tmpfiles.d/legacy.conf                  |  6 +++---

 tmpfiles.d/systemd-nologin.conf         | 11 +++++++++++

 tmpfiles.d/systemd.conf                 |  4 +---

 tmpfiles.d/x11.conf                     |  2 +-

 units/systemd-tmpfiles-setup.service.in |  6 ++++--

 9 files changed, 71 insertions(+), 12 deletions(-)

 create mode 100644 tmpfiles.d/systemd-nologin.conf

diff --git a/Makefile.am b/Makefile.am

index 16a5c3c..6233a7f 100644

--- a/Makefile.am

+++ b/Makefile.am

@@ -1599,6 +1599,7 @@ nodist_systemunit_DATA += \

 dist_tmpfiles_DATA = \

 	tmpfiles.d/systemd.conf \

+	tmpfiles.d/systemd-nologin.conf \

 	tmpfiles.d/tmp.conf \

 	tmpfiles.d/x11.conf

diff --git a/man/systemd-tmpfiles.xml b/man/systemd-tmpfiles.xml

index 91c0372..495247e 100644

--- a/man/systemd-tmpfiles.xml

+++ b/man/systemd-tmpfiles.xml

@@ -133,6 +133,12 @@

                                 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

                                 apply to paths with the specified

diff --git a/man/tmpfiles.d.xml b/man/tmpfiles.d.xml

index a00637b..39aa68d 100644

--- a/man/tmpfiles.d.xml

+++ b/man/tmpfiles.d.xml

@@ -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>

diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c

index 00f74c2..30a8a55 100644

--- a/src/tmpfiles/tmpfiles.c

+++ b/src/tmpfiles/tmpfiles.c

@@ -106,6 +106,7 @@ 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;

@@ -1073,7 +1074,7 @@ 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;

@@ -1083,8 +1084,8 @@ 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,

@@ -1096,6 +1097,14 @@ 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();

@@ -1266,6 +1275,7 @@ 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);

@@ -1279,6 +1289,7 @@ static int parse_argv(int argc, char *argv[]) {

                 ARG_CREATE,

                 ARG_CLEAN,

                 ARG_REMOVE,

+                ARG_UNSAFE,

                 ARG_PREFIX,

                 ARG_EXCLUDE_PREFIX,

         };

@@ -1288,6 +1299,7 @@ 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 },

                 { NULL,             0,                   NULL, 0                  }

@@ -1318,6 +1330,10 @@ 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();

diff --git a/tmpfiles.d/legacy.conf b/tmpfiles.d/legacy.conf

index 3fff347..a165687 100644

--- a/tmpfiles.d/legacy.conf

+++ b/tmpfiles.d/legacy.conf

@@ -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

diff --git a/tmpfiles.d/systemd-nologin.conf b/tmpfiles.d/systemd-nologin.conf

new file mode 100644

index 0000000..d61232b

--- /dev/null

+++ b/tmpfiles.d/systemd-nologin.conf

@@ -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)"

diff --git a/tmpfiles.d/systemd.conf b/tmpfiles.d/systemd.conf

index a05c657..7c6d6b9 100644

--- a/tmpfiles.d/systemd.conf

+++ b/tmpfiles.d/systemd.conf

@@ -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 - -

diff --git a/tmpfiles.d/x11.conf b/tmpfiles.d/x11.conf

index ece6a5c..4c96a54 100644

--- a/tmpfiles.d/x11.conf

+++ b/tmpfiles.d/x11.conf

@@ -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

diff --git a/units/systemd-tmpfiles-setup.service.in b/units/systemd-tmpfiles-setup.service.in

index 3405e28..c2dcae0 100644

--- a/units/systemd-tmpfiles-setup.service.in

+++ b/units/systemd-tmpfiles-setup.service.in

@@ -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