Fixed #19866 -- Added security logger and return 400 for SuspiciousOperation.

SuspiciousOperations have been differentiated into subclasses, and
are now logged to a 'django.security.*' logger. SuspiciousOperations
that reach django.core.handlers.base.BaseHandler will now return a 400
instead of a 500.

Thanks to tiwoc for the report, and Carl Meyer and Donald Stufft
for review.

django/http/multipartparser.py

@@ -11,7 +11,7 @@ import cgi
 import sys
 
 from django.conf import settings
-from django.core.exceptions import SuspiciousOperation
+from django.core.exceptions import SuspiciousMultipartForm
 from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_text
 from django.utils import six
@@ -370,7 +370,7 @@ class LazyStream(six.Iterator):
                             if current_number == num_bytes])
 
         if number_equal > 40:
-            raise SuspiciousOperation(
+            raise SuspiciousMultipartForm(
                 "The multipart parser got stuck, which shouldn't happen with"
                 " normal uploaded files. Check for malicious upload activity;"
                 " if there is none, report this to the Django developers."

django/http/request.py

@@ -14,7 +14,7 @@ except ImportError:
 
 from django.conf import settings
 from django.core import signing
-from django.core.exceptions import SuspiciousOperation, ImproperlyConfigured
+from django.core.exceptions import DisallowedHost, ImproperlyConfigured
 from django.core.files import uploadhandler
 from django.http.multipartparser import MultiPartParser
 from django.utils import six
@@ -72,7 +72,7 @@ class HttpRequest(object):
             msg = "Invalid HTTP_HOST header: %r." % host
             if domain:
                 msg += "You may need to add %r to ALLOWED_HOSTS." % domain
-            raise SuspiciousOperation(msg)
+            raise DisallowedHost(msg)
 
     def get_full_path(self):
         # RFC 3986 requires query string arguments to be in the ASCII range.

django/http/response.py

@@ -12,7 +12,7 @@ except ImportError:
 from django.conf import settings
 from django.core import signals
 from django.core import signing
-from django.core.exceptions import SuspiciousOperation
+from django.core.exceptions import DisallowedRedirect
 from django.http.cookie import SimpleCookie
 from django.utils import six, timezone
 from django.utils.encoding import force_bytes, iri_to_uri
@@ -452,7 +452,7 @@ class HttpResponseRedirectBase(HttpResponse):
     def __init__(self, redirect_to, *args, **kwargs):
         parsed = urlparse(redirect_to)
         if parsed.scheme and parsed.scheme not in self.allowed_schemes:
-            raise SuspiciousOperation("Unsafe redirect to URL with protocol '%s'" % parsed.scheme)
+            raise DisallowedRedirect("Unsafe redirect to URL with protocol '%s'" % parsed.scheme)
         super(HttpResponseRedirectBase, self).__init__(*args, **kwargs)
         self['Location'] = iri_to_uri(redirect_to)