Set KRB5CCNAME so httpd s4u2proxy can with with newer krb5-server

The DIR ccache format is now the default in krb5-server 1.11.2-4
but /run/user/<uid> isn't created for Apache by anything so it
has no ccache (and it doesn't have SELinux permissions to write here
either).

Use KRB5CCNAME to set a file path instead in /etc/sysconfig/httpd.

https://fedorahosted.org/freeipa/ticket/3607

install/tools/ipa-upgradeconfig

@@ -916,6 +916,7 @@ def main():
     http = httpinstance.HTTPInstance(fstore)
     http.remove_httpd_ccache()
     http.configure_selinux_for_httpd()
+    http.configure_httpd_ccache()
 
     ds = dsinstance.DsInstance()
 

ipaserver/install/httpinstance.py

@@ -22,6 +22,7 @@ import os.path
 import tempfile
 import pwd
 import shutil
+import stat
 
 import service
 import certs
@@ -99,6 +100,7 @@ class HTTPInstance(service.Service):
         self.step("creating a keytab for httpd", self.__create_http_keytab)
         self.step("clean up any existing httpd ccache", self.remove_httpd_ccache)
         self.step("configuring SELinux for httpd", self.configure_selinux_for_httpd)
+        self.step("configure httpd ccache", self.configure_httpd_ccache)
         self.step("restarting httpd", self.__start)
         self.step("configuring httpd to start on boot", self.__enable)
 
@@ -192,6 +194,22 @@ class HTTPInstance(service.Service):
         pent = pwd.getpwnam("apache")
         installutils.remove_file('/tmp/krb5cc_%d' % pent.pw_uid)
 
+    def configure_httpd_ccache(self):
+        pent = pwd.getpwnam("apache")
+        ccache = '/tmp/krb5cc_%d' % pent.pw_uid
+        filepath = '/etc/sysconfig/httpd'
+        if not os.path.exists(filepath):
+            # file doesn't exist; create it with correct ownership & mode
+            open(filepath, 'a').close()
+            os.chmod(filepath,
+                stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH)
+            os.chown(filepath, 0, 0)
+
+        replacevars = {'KRB5CCNAME': ccache}
+        old_values = ipautil.backup_config_and_replace_variables(
+            self.fstore, filepath, replacevars=replacevars)
+        ipaservices.restore_context(filepath)
+
     def __configure_http(self):
         target_fname = '/etc/httpd/conf.d/ipa.conf'
         http_txt = ipautil.template_file(ipautil.SHARE_DIR + "ipa.conf", self.sub_dict)