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# IVLE - Informatics Virtual Learning Environment
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# Copyright (C) 2007-2008 The University of Melbourne
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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# Provides functions for translating URLs into physical locations in the
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# student directories in the local file system.
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# Also performs common authorization, disallowing students from visiting paths
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def url_to_local(config, urlpath):
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"""Given a URL path (part of a URL query string, see below), returns a
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* the username of the student whose directory is being browsed
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* the absolute path in the file system where that file will be
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found within the student directories.
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urlpath: Part of the URL, but only the part *after* the application. For
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instance, given the URL "/ivle/browse/joe/mydir/myfile", urlpath will
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be just "joe/mydir/myfile". The expected result is something like
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("joe", "/home/informatics/jails/joe/home/joe/mydir/myfile").
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Note that the actual location is not guaranteed by this interface (this
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function serves as a single point of control as to how URLs map onto
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Returns (None, None) if the path is empty.
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>>> stubconfig = {'paths': {'jails': {'mounts': '/jails'}}}
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>>> url_to_local(stubconfig, 'joe/foo/bar/baz')
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('joe', '/jails/joe/home/joe/foo/bar/baz')
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>>> url_to_local(stubconfig, 'joe')
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('joe', '/jails/joe/home/joe')
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>>> url_to_local(stubconfig, 'joe/')
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('joe', '/jails/joe/home/joe')
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We have some protection from various potential attacks. An empty,
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absolute, or ..-prefixed path yields a special result.
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>>> url_to_local(stubconfig, '')
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>>> url_to_local(stubconfig, '/foo')
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>>> url_to_local(stubconfig, '../bar')
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# First normalise the path
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urlpath = os.path.normpath(urlpath)
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# Now if it begins with ".." or separator, then it's illegal
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if urlpath.startswith("..") or urlpath.startswith(os.sep):
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# Note: User can be a group name. There is absolutely no difference in our
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# current directory scheme.
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(user, subpath) = util.split_path(urlpath)
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if user is None: return (None, None)
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# Join the user onto 'home' then the full path specified.
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# This results in the user's name being repeated twice, which is in
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# accordance with our directory scheme.
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# (The first time is the name of the jail, the second is the user's home
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# directory within the jail).
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path = os.path.join(config['paths']['jails']['mounts'],
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user, 'home', urlpath)
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def url_to_jailpaths(config, urlpath):
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"""Given a URL path (part of a URL query string), returns a tuple of
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* the username of the student whose directory is being browsed
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* the absolute path where the jail will be located.
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* the path of the file relative to the jail.
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urlpath: See urlpath in url_to_local.
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>>> stubconfig = {'paths': {'jails': {'mounts': '/jails'}}}
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>>> url_to_jailpaths(stubconfig, "joe/mydir//myfile/.././myfile")
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('joe', '/jails/joe', '/home/joe/mydir/myfile')
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>>> url_to_jailpaths(stubconfig, "")
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>>> url_to_jailpaths(stubconfig, "../foo")
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>>> url_to_jailpaths(stubconfig, "/foo")
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# First normalise the path
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urlpath = os.path.normpath(urlpath)
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# Now if it begins with "..", or is absolute, then it's illegal
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if urlpath.startswith("..") or os.path.isabs(urlpath):
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return (None, None, None)
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# Note: User can be a group name. There is absolutely no difference in our
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# current directory scheme.
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(user, subpath) = util.split_path(urlpath)
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if user is None: return (None, None, None)
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jail = os.path.join(config['paths']['jails']['mounts'], user)
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path = to_home_path(urlpath)
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return (user, jail, path)
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def to_home_path(urlpath):
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"""Given a URL path (eg. joe/foo/bar/baz), returns a path within the home.
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>>> to_home_path('joe/foo/bar/baz')
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'/home/joe/foo/bar/baz'
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>>> to_home_path('joe/foo//bar/baz/../../')
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>>> to_home_path('joe/foo//bar/baz/../../../../../') is None
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urlpath = os.path.normpath(urlpath)
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# If it begins with '..', it's illegal.
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if urlpath.startswith(".."):
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return os.path.join('/home', urlpath)
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"""Given a path on the LOCAL file system, determines whether the path has a
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'.published' file. Returns True or False."""
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publish_file_path = os.path.join(path,'.published')
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return os.access(publish_file_path,os.F_OK)
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def worldreadable(path):
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"""Given a path on the LOCAL file system, determines whether the path is
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world readble. Returns True or False."""
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mode = os.stat(path).st_mode
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if mode & stat.S_IROTH:
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def authorize(req, user):
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"""Given a request, checks whether req.user is allowed to
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access req.path. Returns None on authorization success. Raises
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HTTP_FORBIDDEN on failure.
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This is for general authorization (assuming not in public mode; this is
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the standard auth code for fileservice, download and serve).
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# First normalise the path
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urlpath = os.path.normpath(req.path)
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# Now if it begins with ".." or separator, then it's illegal
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if urlpath.startswith("..") or urlpath.startswith(os.sep):
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(owner, _) = util.split_path(urlpath)
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if user.login != owner:
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def authorize_public(req):
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"""A different kind of authorization. Rather than making sure the
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logged-in user owns the file, this checks if the file is in a published
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This is for the "public mode" of the serve app.
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Same interface as "authorize" - None on success, HTTP_FORBIDDEN exception
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_, path = url_to_local(req.config, req.path)
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# Walk up the tree, and find the deepest directory.
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while not os.path.isdir(path):
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path = os.path.dirname(path)
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if not (worldreadable(path) and published(path)):
added
removed
ivle/studpath.py
