Replace yaml.load() with yaml.safe_load()

Avoid dangerous file parsing and object serialization libraries.
yaml.load is the obvious function to use but it is dangerous[1]
Because yaml.load return Python object may be dangerous if you
receive a YAML document from an untrusted source such as the
Internet. The function yaml.safe_load limits this ability to
simple Python objects like integers or lists.
In addition, Bandit flags yaml.load() as security risk
so replace all occurrences with yaml.safe_load().
Thus I replace yaml.load() with yaml.safe_load()

[1]https://security.openstack.org/guidelines/dg_avoid-dangerous-input-parsing-libraries.html

Change-Id: Iaa2b7d9c880f3e20243bb2a9cbd8f9db29ecc267

ci-scripts/linters/lint-browbeat-config.py

@@ -16,7 +16,7 @@ import sys
 from pykwalify import core as pykwalify_core
 from pykwalify import errors as pykwalify_errors
 stream = open(sys.argv[1], 'r')
-schema = yaml.load(stream)
+schema = yaml.safe_load(stream)
 check = pykwalify_core.Core(sys.argv[2], schema_data=schema)
 try:
     check.validate(raise_exception=True)

lib/Shaker.py

@@ -244,7 +244,7 @@ class Shaker(WorkloadBase.WorkloadBase):
 
     def set_scenario(self, scenario, fname, default_time):
         stream = open(fname, 'r')
-        data = yaml.load(stream)
+        data = yaml.safe_load(stream)
         stream.close()
         default_density = 1
         default_compute = 1

lib/Tools.py

@@ -71,7 +71,7 @@ class Tools(object):
             self.logger.error(
                 "Configuration file {} passed is missing".format(path))
             exit(1)
-        config = yaml.load(stream)
+        config = yaml.safe_load(stream)
         stream.close()
         self.config = config
         if validate:
@@ -82,7 +82,7 @@ class Tools(object):
         self.logger.info(
             "Validating the configuration file passed by the user")
         stream = open("lib/validate.yaml", 'r')
-        schema = yaml.load(stream)
+        schema = yaml.safe_load(stream)
         check = pykwalify_core.Core(
             source_data=self.config, schema_data=schema)
         try: