[Python-checkins] cpython (3.1): use the collapsed path in the run_cgi method (closes #19435)

[benjamin.peterson]

http://hg.python.org/cpython/rev/b1ddcb220a7f
changeset:   86777:b1ddcb220a7f
branch:      3.1
parent:      85751:713d71048ab9
user:        Benjamin Peterson <benjamin at python.org>
date:        Wed Oct 30 12:43:09 2013 -0400
summary:
  use the collapsed path in the run_cgi method (closes #19435)

files:
  Lib/http/server.py           |   9 ++++-----
  Lib/test/test_httpservers.py |  10 ++++++++++
  Misc/NEWS                    |   2 ++
  3 files changed, 16 insertions(+), 5 deletions(-)


diff --git a/Lib/http/server.py b/Lib/http/server.py
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -926,18 +926,17 @@
 
     def run_cgi(self):
         """Execute a CGI script."""
-        path = self.path
         dir, rest = self.cgi_info
 
-        i = path.find('/', len(dir) + 1)
+        i = rest.find('/')
         while i >= 0:
-            nextdir = path[:i]
-            nextrest = path[i+1:]
+            nextdir = rest[:i]
+            nextrest = rest[i+1:]
 
             scriptdir = self.translate_path(nextdir)
             if os.path.isdir(scriptdir):
                 dir, rest = nextdir, nextrest
-                i = path.find('/', len(dir) + 1)
+                i = rest.find('/')
             else:
                 break
 
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -388,6 +388,11 @@
         else:
             self.pythonexe = sys.executable
 
+        self.nocgi_path = os.path.join(self.parent_dir, 'nocgi.py')
+        with open(self.nocgi_path, 'w') as fp:
+            fp.write(cgi_file1 % self.pythonexe)
+        os.chmod(self.nocgi_path, 0o777)
+
         self.file1_path = os.path.join(self.cgi_dir, 'file1.py')
         with open(self.file1_path, 'w') as file1:
             file1.write(cgi_file1 % self.pythonexe)
@@ -406,6 +411,7 @@
             os.chdir(self.cwd)
             if self.pythonexe != sys.executable:
                 os.remove(self.pythonexe)
+            os.remove(self.nocgi_path)
             os.remove(self.file1_path)
             os.remove(self.file2_path)
             os.rmdir(self.cgi_dir)
@@ -457,6 +463,10 @@
         self.assertEqual((b'Hello World\n', 'text/html', 200), \
              (res.read(), res.getheader('Content-type'), res.status))
 
+    def test_issue19435(self):
+        res = self.request('///////////nocgi.py/../cgi-bin/nothere.sh')
+        self.assertEqual(res.status, 404)
+
     def test_post(self):
         params = urllib.parse.urlencode(
             {'spam' : 1, 'eggs' : 'python', 'bacon' : 123456})
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -13,6 +13,8 @@
 Library
 -------
 
+- Issue #19435: Fix directory traversal attack on CGIHttpRequestHandler.
+
 - Issue #14984: On POSIX systems, when netrc is called without a filename
   argument (and therefore is reading the user's $HOME/.netrc file), it now
   enforces the same security rules as typical ftp clients: the .netrc file must

-- 
Repository URL: http://hg.python.org/cpython