Add selinux support to file module

This adds the options: seuser, serole, setype, and serange to the file
module.  If the python selinux module doesn't exist, this will set
HAVE_SELINUX to False and punt in the related modules.

This takes the options the user provides and applies those to the
default selinux context as provided from matchpathcon().  If there is no
default context, this uses the value from the current context.  This
implies that if you set the setype and later remove it, the file module
will rever the setype to the default if available.

library/file

@@ -29,6 +29,11 @@ import shutil
 import stat
 import grp
 import pwd
+try:
+    import selinux
+    HAVE_SELINUX=True
+except ImportError:
+    HAVE_SELINUX=False
 
 def debug(msg):
     # ansible ignores stderr, so it's safe to use for debug
@@ -61,6 +66,8 @@ def add_path_info(kwargs):
             kwargs['state'] = 'file'
         else:
             kwargs['state'] = 'directory'
+        if HAVE_SELINUX:
+            kwargs['secontext'] = ':'.join(selinux_context(path))
     else:
         kwargs['state'] = 'absent'
     return kwargs 
@@ -91,8 +98,12 @@ group     = params.get('group', None)
 # presently unused, we always use -R (FIXME?)
 recurse   = params.get('recurse', 'false')
 
-# presently unused, implement (FIXME)
-secontext = params.get('secontext', None)
+# selinux related options
+seuser    = params.get('seuser', None)
+serole    = params.get('serole', None)
+setype    = params.get('setype', None)
+serange   = params.get('serange', 's0')
+secontext = [seuser, serole, setype, serange]
 
 if state not in [ 'file', 'directory', 'link', 'absent']:
     fail_json(msg='invalid state: %s' % state)
@@ -119,12 +130,59 @@ def user_and_group(filename):
     debug("got user=%s and group=%s" % (user, group))
     return (user, group)
 
-    
+def selinux_context(path):
+    context = [None, None, None, None]
+    if not HAVE_SELINUX:
+        return context
+    try:
+        ret = selinux.lgetfilecon(path)
+    except:
+        fail_json(path=path, msg='failed to retrieve selinux context')
+    if ret[0] == -1:
+        return context
+    context = ret[1].split(':')
+    debug("got current secontext=%s" % ret[1])
+    return context
+
+# If selinux fails to find a default, return an array of None
+def selinux_default_context(path, mode=0):
+    context = [None, None, None, None]
+    print >>sys.stderr, path
+    if not HAVE_SELINUX:
+        return context
+    try:
+        ret = selinux.matchpathcon(path, mode)
+    except OSError:
+        return context
+    if ret[0] == -1:
+        return context
+    context = ret[1].split(':')
+    debug("got default secontext=%s" % ret[1])
+    return context
+
 def set_context_if_different(path, context, changed):
-   if context is None:
-       return changed
-   if context is not None:
-       fail_json(path=path, msg='context not yet supported')
+    if not HAVE_SELINUX:
+        return changed
+    cur_context = selinux_context(path)
+    new_context = selinux_default_context(path)
+    for i in range(len(context)):
+        if context[i] is not None and context[i] != cur_context[i]:
+            debug('new context was %s' % new_context[i])
+            new_context[i] = context[i]
+            debug('new context is %s' % new_context[i])
+        elif new_context[i] is None:
+            new_context[i] = cur_context[i]
+    debug("current secontext is %s" % ':'.join(cur_context))
+    debug("new secontext is %s" % ':'.join(new_context))
+    if cur_context != new_context:
+        try:
+            rc = selinux.lsetfilecon(path, ':'.join(new_context))
+        except OSError:
+            fail_json(path=path, msg='invalid selinux context')
+        if rc != 0:
+            fail_json(path=path, msg='set selinux context failed')
+        changed = True
+    return changed
     
 def set_owner_if_different(path, owner, changed):
    if owner is None: