Merge pull request #639 from Klaas-/Klaas-fix_authorized_key (#731)

Fixes #462 notice permission denied on authorized_key module

SUMMARY
As of right now the authorized_key module does not notice on an "absent" if a authorized_keys file is simply not readable to the executing user. I am trying to fix that
ISSUE TYPE

Bugfix Pull Request

COMPONENT NAME
authorized_key
ADDITIONAL INFORMATION

Execute as a user that does not have access to the root users authorized keys file

- name: Delete key from root user
  ansible.posix.authorized_key:
    state: absent
    user: root
    key: ssh-rsa xxxxxxxx

- name: Delete key from root user
  become: true
  ansible.posix.authorized_key:
    state: absent
    user: root
    key: ssh-rsa xxxxxxxx

The one without become will succeed before my change and will fail with a permission denied error after my change. The 2nd task will actually remove a key from root user if become privileges are available for the executing user

Reviewed-by: Brian Coca
Reviewed-by: Klaas Demter
Reviewed-by: Felix Fontein <felix@fontein.de>
Reviewed-by: Hideki Saito <saito@fgrep.org>
(cherry picked from commit 72a6eb9729)

Co-authored-by: softwarefactory-project-zuul[bot] <33884098+softwarefactory-project-zuul[bot]@users.noreply.github.com>

plugins/modules/authorized_key.py

@@ -225,6 +225,8 @@ import os.path
 import tempfile
 import re
 import shlex
+import errno
+import traceback
 from operator import itemgetter
 
 from ansible.module_utils._text import to_native
@@ -475,16 +477,18 @@ def parsekey(module, raw_key, rank=None):
     return (key, key_type, options, comment, rank)
 
 
-def readfile(filename):
-
-    if not os.path.isfile(filename):
-        return ''
-
-    f = open(filename)
+def readfile(module, filename):
     try:
-        return f.read()
-    finally:
-        f.close()
+        with open(filename, 'r') as f:
+            return f.read()
+    except IOError as e:
+        if e.errno == errno.EACCES:
+            module.fail_json(msg="Permission denied on file or path for authorized keys file: %s" % filename,
+                             exception=traceback.format_exc())
+        elif e.errno == errno.ENOENT:
+            return ''
+        else:
+            raise
 
 
 def parsekeys(module, lines):
@@ -597,7 +601,7 @@ def enforce_state(module, params):
     # check current state -- just get the filename, don't create file
     do_write = False
     params["keyfile"] = keyfile(module, user, do_write, path, manage_dir)
-    existing_content = readfile(params["keyfile"])
+    existing_content = readfile(module, params["keyfile"])
     existing_keys = parsekeys(module, existing_content)
 
     # Add a place holder for keys that should exist in the state=present and