view roundup/cgi/cgitb.py @ 5201:a9ace22e0a2f

issue 2550690 - Adding anti-csrf measures to roundup following https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet and https://seclab.stanford.edu/websec/csrf/csrf.pdf Basically implement Synchronizer (CSRF) Tokens per form on a page. Single use (destroyed once used). Random input data for the token includes: system random implementation in python using /dev/urandom (fallback to random based on timestamp as the seed. Not as good, but should be ok for the short lifetime of the token??) the id (in cpython it's the memory address) of the object requesting a token. In theory this depends on memory layout, the history of the process (how many previous objects have been allocated from the heap etc.) I claim without any proof that for long running processes this is another source of randomness. For short running processes with little activity it could be guessed. last the floating point time.time() value is added. This may only have 1 second resolution so may be guessable. Hopefully for a short lived (2 week by default) token this is sufficient. Also in the current implementation the user is notified when validation fails and is told why. This allows the roundup admin to find the log entry (at error level) and try to resolve the issue. In the future user notification may change but for now this is probably best.
author John Rouillard <rouilj@ieee.org>
date Sat, 18 Mar 2017 16:59:01 -0400
parents 6e3e4f24c753
children 64b05e24dbd8
line wrap: on
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#
# This module was written by Ka-Ping Yee, <ping@lfw.org>.
#

"""Extended CGI traceback handler by Ka-Ping Yee, <ping@lfw.org>.
"""
__docformat__ = 'restructuredtext'

import sys, os, types, string, keyword, linecache, tokenize, inspect, cgi
import pydoc, traceback

from roundup.cgi import templating, TranslationService

def get_translator(i18n=None):
    """Return message translation function (gettext)

    Parameters:
        i18n - translation service, such as roundup.i18n module
            or TranslationService object.

    Return ``gettext`` attribute of the ``i18n`` object, if available
    (must be a message translation function with one argument).
    If ``gettext`` cannot be obtained from ``i18n``, take default
    TranslationService.

    """
    try:
        return i18n.gettext
    except:
        return TranslationService.get_translation().gettext

def breaker():
    return ('<body bgcolor="white">' +
            '<font color="white" size="-5"> > </font> ' +
            '</table>' * 5)

def niceDict(indent, dict):
    l = []
    for k in sorted(dict):
        v = dict[k]
        l.append('<tr><td><strong>%s</strong></td><td>%s</td></tr>'%(k,
            cgi.escape(repr(v))))
    return '\n'.join(l)

def pt_html(context=5, i18n=None):
    _ = get_translator(i18n)
    esc = cgi.escape
    exc_info = [esc(str(value)) for value in sys.exc_info()[:2]]
    l = [_('<h1>Templating Error</h1>\n'
            '<p><b>%(exc_type)s</b>: %(exc_value)s</p>\n'
            '<p class="help">Debugging information follows</p>'
         ) % {'exc_type': exc_info[0], 'exc_value': exc_info[1]},
         '<ol>',]
    from roundup.cgi.PageTemplates.Expressions import TraversalError
    t = inspect.trace(context)
    t.reverse()
    for frame, file, lnum, func, lines, index in t:
        args, varargs, varkw, locals = inspect.getargvalues(frame)
        if '__traceback_info__' in locals:
            ti = locals['__traceback_info__']
            if isinstance(ti, TraversalError):
                s = []
                for name, info in ti.path:
                    s.append(_('<li>"%(name)s" (%(info)s)</li>')
                        % {'name': name, 'info': esc(repr(info))})
                s = '\n'.join(s)
                l.append(_('<li>Looking for "%(name)s", '
                    'current path:<ol>%(path)s</ol></li>'
                ) % {'name': ti.name, 'path': s})
            else:
                l.append(_('<li>In %s</li>') % esc(str(ti)))
        if '__traceback_supplement__' in locals:
            ts = locals['__traceback_supplement__']
            if len(ts) == 2:
                supp, context = ts
                s = _('A problem occurred in your template "%s".') \
                    % str(context.id)
                if context._v_errors:
                    s = s + '<br>' + '<br>'.join(
                        [esc(x) for x in context._v_errors])
                l.append('<li>%s</li>'%s)
            elif len(ts) == 3:
                supp, context, info = ts
                l.append(_('''
<li>While evaluating the %(info)r expression on line %(line)d
<table class="otherinfo" style="font-size: 90%%">
 <tr><th colspan="2" class="header">Current variables:</th></tr>
 %(globals)s
 %(locals)s
</table></li>
''') % {
    'info': info,
    'line': context.position[0],
    'globals': niceDict('    ', context.global_vars),
    'locals': niceDict('    ', context.local_vars)
})

    l.append('''
</ol>
<table style="font-size: 80%%; color: gray">
 <tr><th class="header" align="left">%s</th></tr>
 <tr><td><pre>%s</pre></td></tr>
</table>''' % (_('Full traceback:'), cgi.escape(''.join(
        traceback.format_exception(*sys.exc_info())
    ))))
    l.append('<p>&nbsp;</p>')
    return '\n'.join(l)

def html(context=5, i18n=None):
    _ = get_translator(i18n)
    etype, evalue = sys.exc_info()[0], sys.exc_info()[1]
    if type(etype) is type:
        etype = etype.__name__
    pyver = 'Python ' + string.split(sys.version)[0] + '<br>' + sys.executable
    head = pydoc.html.heading(
        _('<font size=+1><strong>%(exc_type)s</strong>: %(exc_value)s</font>')
        % {'exc_type': etype, 'exc_value': evalue},
        '#ffffff', '#777777', pyver)

    head = head + (_('<p>A problem occurred while running a Python script. '
                   'Here is the sequence of function calls leading up to '
                   'the error, with the most recent (innermost) call first. '
                   'The exception attributes are:'))

    indent = '<tt><small>%s</small>&nbsp;</tt>' % ('&nbsp;' * 5)
    traceback = []
    for frame, file, lnum, func, lines, index in inspect.trace(context):
        if file is None:
            link = _("&lt;file is None - probably inside <tt>eval</tt> "
                "or <tt>exec</tt>&gt;")
        else:
            file = os.path.abspath(file)
            link = '<a href="file:%s">%s</a>' % (file, pydoc.html.escape(file))
        args, varargs, varkw, locals = inspect.getargvalues(frame)
        if func == '?':
            call = ''
        else:
            call = _('in <strong>%s</strong>') % func + inspect.formatargvalues(
                    args, varargs, varkw, locals,
                    formatvalue=lambda value: '=' + pydoc.html.repr(value))

        level = '''
<table width="100%%" bgcolor="#dddddd" cellspacing=0 cellpadding=2 border=0>
<tr><td>%s %s</td></tr></table>''' % (link, call)

        if index is None or file is None:
            traceback.append('<p>' + level)
            continue

        # do a file inspection
        names = []
        def tokeneater(type, token, start, end, line, names=names):
            if type == tokenize.NAME and token not in keyword.kwlist:
                if token not in names:
                    names.append(token)
            if type == tokenize.NEWLINE: raise IndexError
        def linereader(file=file, lnum=[lnum]):
            line = linecache.getline(file, lnum[0])
            lnum[0] = lnum[0] + 1
            return line

        try:
            tokenize.tokenize(linereader, tokeneater)
        except IndexError:
            pass
        lvals = []
        for name in names:
            if name in frame.f_code.co_varnames:
                if name in locals:
                    value = pydoc.html.repr(locals[name])
                else:
                    value = _('<em>undefined</em>')
                name = '<strong>%s</strong>' % name
            else:
                if name in frame.f_globals:
                    value = pydoc.html.repr(frame.f_globals[name])
                else:
                    value = _('<em>undefined</em>')
                name = '<em>global</em> <strong>%s</strong>' % name
            lvals.append('%s&nbsp;= %s'%(name, value))
        if lvals:
            lvals = string.join(lvals, ', ')
            lvals = indent + '<small><font color="#909090">%s'\
                '</font></small><br>'%lvals
        else:
            lvals = ''

        excerpt = []
        i = lnum - index
        for line in lines:
            number = '&nbsp;' * (5-len(str(i))) + str(i)
            number = '<small><font color="#909090">%s</font></small>' % number
            line = '<tt>%s&nbsp;%s</tt>' % (number, pydoc.html.preformat(line))
            if i == lnum:
                line = '''
<table width="100%%" bgcolor="white" cellspacing=0 cellpadding=0 border=0>
<tr><td>%s</td></tr></table>''' % line
            excerpt.append('\n' + line)
            if i == lnum:
                excerpt.append(lvals)
            i = i + 1
        traceback.append('<p>' + level + string.join(excerpt, '\n'))

    traceback.reverse()

    exception = '<p><strong>%s</strong>: %s' % (str(etype), str(evalue))
    attribs = []
    if type(evalue) is types.InstanceType:
        for name in dir(evalue):
            value = pydoc.html.repr(getattr(evalue, name))
            attribs.append('<br>%s%s&nbsp;= %s' % (indent, name, value))

    return head + string.join(attribs) + string.join(traceback) + '<p>&nbsp;</p>'

def handler():
    print breaker()
    print html()

# vim: set filetype=python ts=4 sw=4 et si :

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