MDEV-37726 wsrep-new-cluster and wsrep-start-position in wrong directory with wrong selinux permissions

After moving the systemd service to using environment files
instead of `systemctl set-environment` in 11.6 (MDEV-19210),
they (wsrep-new-cluster and wsrep-start-position) are located
in /var/lib/mysql along with the socket file in
Fedora/RHEL-based distros. This causes them to have incorrect
selinux permissions and therefore be not readable by systemd.

A solution is to generate these files in the run directory,
instead, which already has correct selinux label mysqld_var_run_t
mysql-selinux-1.0.12. Dissociating these files and the socket
in CMake configs can also prove useful for other things.

This also corrects some of the duplicate code in the build
scripts and made INSTALL_RUNDATADIR into a proper location
and used this for the tmpfiles where the temporary files
are created.

Debian's location is /run/mysqld/ matching its INSTALL_UNIX_ADDRDIR,
which is now a temporary location controlled by tmpfiles.

cmake/install_layout.cmake

@@ -163,6 +163,7 @@ SET(INSTALL_UNIX_ADDRDIR_RPM            "${INSTALL_MYSQLDATADIR_RPM}/mysql.sock"
 SET(INSTALL_SYSTEMD_UNITDIR_RPM         "/usr/lib/systemd/system")
 SET(INSTALL_SYSTEMD_SYSUSERSDIR_RPM     "/usr/lib/sysusers.d")
 SET(INSTALL_SYSTEMD_TMPFILESDIR_RPM     "/usr/lib/tmpfiles.d")
+SET(INSTALL_RUNDATADIR_RPM              "/run/mariadb")
 SET(INSTALL_PAMDIR_RPM                  "/${INSTALL_LIBDIR_RPM}/security")
 SET(INSTALL_PAMDATADIR_RPM              "/etc/security")
 
@@ -193,7 +194,8 @@ SET(INSTALL_SUPPORTFILESDIR_DEB         "share/mysql")
 #
 SET(INSTALL_MYSQLDATADIR_DEB            "/var/lib/mysql")
 
-SET(INSTALL_UNIX_ADDRDIR_DEB            "/run/mysqld/mysqld.sock")
+SET(INSTALL_RUNDATADIR_DEB              "/run/mysqld")
+SET(INSTALL_UNIX_ADDRDIR_DEB            "${INSTALL_RUNDATADIR_DEB}/mysqld.sock")
 SET(INSTALL_SYSTEMD_UNITDIR_DEB         "/lib/systemd/system")
 SET(INSTALL_SYSTEMD_SYSUSERSDIR_DEB     "/usr/lib/sysusers.d")
 SET(INSTALL_SYSTEMD_TMPFILESDIR_DEB     "/usr/lib/tmpfiles.d")
@@ -257,3 +259,7 @@ IF(NOT MYSQL_UNIX_ADDR)
   SET(MYSQL_UNIX_ADDR ${INSTALL_UNIX_ADDRDIR})
 ENDIF()
 
+IF(NOT INSTALL_RUNDATADIR)
+  get_filename_component(MYSQL_UNIX_DIR ${MYSQL_UNIX_ADDR} DIRECTORY)
+  SET(INSTALL_RUNDATADIR "${MYSQL_UNIX_DIR}" CACHE FILEPATH "Rundata installation directory" ${FORCE})
+ENDIF()

scripts/galera_new_cluster.sh

@@ -21,11 +21,11 @@ EOF
     exit 0
 fi
 
-systemctl set-environment _WSREP_NEW_CLUSTER='--wsrep-new-cluster' && \
-    systemctl restart ${1:-mariadb}
+echo _WSREP_NEW_CLUSTER='--wsrep-new-cluster' > "@INSTALL_RUNDATADIR@/wsrep-new-cluster" && \
+    systemctl restart mariadb.service
 
 extcode=$?
 
-systemctl set-environment _WSREP_NEW_CLUSTER=''
+rm -f "@INSTALL_RUNDATADIR@/wsrep-new-cluster"
 
 exit $extcode

support-files/CMakeLists.txt

@@ -45,8 +45,6 @@ ELSE()
   IF(DEB)
     SET(su_user "#su mysql mysql")
   ENDIF()
-  get_filename_component(MYSQL_UNIX_DIR ${MYSQL_UNIX_ADDR} DIRECTORY)
-  SET(mysqlunixdir ${MYSQL_UNIX_DIR})
 ENDIF()
 
 # XXX: shouldn't we just have variables for all this stuff and centralise
@@ -212,8 +210,11 @@ IF(UNIX AND NOT WITHOUT_SERVER)
             RENAME mariadb.conf COMPONENT Server)
   ENDIF()
 
-  IF((HAVE_SYSTEMD OR INSTALL_SYSTEMD_TMPUSERS) AND INSTALL_SYSTEMD_TMPFILESDIR)
-    get_filename_component(MYSQL_UNIX_DIR ${MYSQL_UNIX_ADDR} DIRECTORY)
+  IF((HAVE_SYSTEMD OR INSTALL_SYSTEMD_TMPUSERS) AND INSTALL_SYSTEMD_TMPFILESDIR
+     AND INSTALL_RUNDATADIR)
+    IF(MYSQL_DATADIR STREQUAL INSTALL_RUNDATADIR)
+      SET(DISABLE_TMP "#")
+    ENDIF()
     CONFIGURE_FILE(tmpfiles.conf.in
             ${CMAKE_CURRENT_BINARY_DIR}/tmpfiles.conf @ONLY)
     INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/tmpfiles.conf

support-files/mariadb.service.in

@@ -66,22 +66,22 @@ ProtectHome=true
 PermissionsStartOnly=true
 
 # Use an environment file to pass variable _WSREP_NEW_CLUSTER
-EnvironmentFile=-@mysqlunixdir@/wsrep-new-cluster
+EnvironmentFile=-@INSTALL_RUNDATADIR@/wsrep-new-cluster
 
 # Use an environment file to pass variable _WSREP_START_POSITION
-EnvironmentFile=-@mysqlunixdir@/wsrep-start-position
+EnvironmentFile=-@INSTALL_RUNDATADIR@/wsrep-start-position
 
 @SYSTEMD_EXECSTARTPRE@
 
 # Perform automatic wsrep recovery. When server is started without wsrep,
 # galera_recovery simply returns an empty string. In any case, however,
 # the script is not expected to return with a non-zero status.
-# It is always safe to remove @mysqlunixdir@/wsrep-start-position
+# It is always safe to remove @INSTALL_RUNDATADIR@/wsrep-start-position
 # environment file.
 # Do not panic if galera_recovery script is not available. (MDEV-10538)
 ExecStartPre=/bin/sh -c "[ ! -e @bindir@/galera_recovery ] && VAR= || \
  VAR=`@bindir@/galera_recovery`; [ $? -eq 0 ] \
- && echo _WSREP_START_POSITION=$VAR > @mysqlunixdir@/wsrep-start-position || exit 1"
+ && echo _WSREP_START_POSITION=$VAR > @INSTALL_RUNDATADIR@/wsrep-start-position || exit 1"
 
 # Needed to create system tables etc.
 # ExecStartPre=@scriptdir@/mariadb-install-db -u mysql
@@ -93,8 +93,8 @@ ExecStartPre=/bin/sh -c "[ ! -e @bindir@/galera_recovery ] && VAR= || \
 # _WSREP_NEW_CLUSTER is for the exclusive use of the script galera_new_cluster
 ExecStart=@sbindir@/mariadbd $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION
 
-# Unset _WSREP_START_POSITION environment variable.
-ExecStartPost=/bin/rm -f @mysqlunixdir@/wsrep-start-position
+# Unset _WSREP_START_POSITION/_WSREP_NEW_CLUSTER environment variable.
+ExecStartPost=/bin/rm -f @INSTALL_RUNDATADIR@/wsrep-start-position @INSTALL_RUNDATADIR@/wsrep-new-cluster
 
 @SYSTEMD_EXECSTARTPOST@
 

support-files/tmpfiles.conf.in

@@ -1 +1,15 @@
-d @MYSQL_UNIX_DIR@ 0755 @MYSQLD_USER@ @MYSQLD_USER@ -
+# This is the directory where the unix socket
+# of MariaDB may be created.
+#
+# Under Galera this is where an envfile of
+# the Galera start position is stored.
+#
+# Other temporary directories can be created here like:
+# * tmpdir
+# * innodb_tmpdir
+# * innodb_temp_data_file_path
+# * rocksdb_tmpdir
+# etc.
+# It shouldn't be used for datadir which is why it
+# may be disabled.
+@DISABLE_TMP@d @INSTALL_RUNDATADIR@ 0755 @MYSQLD_USER@ @MYSQLD_USER@ -