Use safer tar extraction. Handle error messages in the build process more intelligently.

util/safetar.py

@@ -0,0 +1,52 @@
+import os.path
+import logging
+import copy
+import operator
+
+
+logger = logging.getLogger(__name__)
+
+
+def safe_extractall(tar, path):
+  """Extract all members from the archive to the current working
+     directory and set owner, modification time and permissions on
+     directories afterwards. `path' specifies a different directory
+     to extract to. `members' is optional and must be a subset of the
+     list returned by getmembers().
+  """
+  abs_extract_path = os.path.abspath(path)
+  def is_member_safe(member):
+    """ Returns True if the member is safe, False otherwise. """
+    if member.issym():
+      link_tar_path = os.path.dirname(member.path)
+      abs_link_path = os.path.abspath(os.path.join(path, link_tar_path, member.linkpath))
+      if not abs_link_path.startswith(abs_extract_path):
+        logger.warning('Filtering symlink outside of extract dir: %s', member.linkpath)
+        return False
+    elif member.isblk():
+      logger.warning('Filtering block device from tarfile: %s', member.path)
+      return False
+
+    return True
+
+  directories = []
+
+  for tarinfo in tar:
+    if is_member_safe(tarinfo):
+      if tarinfo.isdir():
+        # Extract directories with a safe mode.
+        directories.append(tarinfo)
+        tarinfo = copy.copy(tarinfo)
+        tarinfo.mode = 0700
+      tar.extract(tarinfo, path)
+
+  # Reverse sort directories.
+  directories.sort(key=operator.attrgetter('name'))
+  directories.reverse()
+
+  # Set correct owner, mtime and filemode on directories.
+  for tarinfo in directories:
+    dirpath = os.path.join(path, tarinfo.name)
+    tar.chown(tarinfo, dirpath)
+    tar.utime(tarinfo, dirpath)
+    tar.chmod(tarinfo, dirpath)

workers/dockerfilebuild.py

@@ -17,6 +17,7 @@ from data.queue import dockerfile_build_queue
 from data import model
 from workers.worker import Worker
 from app import app
+from util.safetar import safe_extractall
 
 
 root_logger = logging.getLogger('')
@@ -152,8 +153,14 @@ class DockerfileBuildContext(object):
     for status in build_status:
       fully_unwrapped = ""
       if isinstance(status, dict):
-        if len(status) > 0:
-          fully_unwrapped = status.values()[0]
+        keys_to_extract = ['error', 'status', 'stream']
+        for key in keys_to_extract:
+          if key in status:
+            fully_unwrapped = status[key]
+            break
+        
+        if not fully_unwrapped:
+          logger.debug('Status dict did not have any extractable keys and was: %s', status)
       elif isinstance(status, basestring):
         fully_unwrapped = status
 
@@ -322,7 +329,7 @@ class DockerfileBuildWorker(Worker):
 
     # Save the zip file to temp somewhere
     with tarfile.open(mode='r|*', fileobj=request_file.raw) as tar_stream:
-      tar_stream.extractall(build_dir)
+      safe_extractall(tar_stream, build_dir)
 
     return build_dir