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Copy pathsafeurl.py
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732 lines (561 loc) · 19.9 KB
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# coding: utf8
"""
.. module:: safeurl
synopsis:: An SSRF protection library
.. moduleauthor:: Nicolas Rodriguez <http://github.com/nicolasrod>
"""
from __future__ import unicode_literals
from __future__ import print_function
from numbers import Number
from socket import gethostbyname_ex
import re
import netaddr
import pycurl
import StringIO
# Python 2.7/3 urlparse
try:
# Python 2.7
from urlparse import urlparse
from urllib import quote
except:
# Python 3
from urllib.parse import urlparse
from urllib.parse import quote
class InvalidOptionException(Exception):
pass
class InvalidURLException(Exception):
pass
class InvalidDomainException(Exception):
pass
class InvalidIPException(Exception):
pass
class InvalidPortException(Exception):
pass
class InvalidSchemeException(Exception):
pass
class Empty(object):
pass
# TODO: Remove this ugly hack!
def _mutable(obj):
newobj = Empty()
for i in dir(obj):
if not i.startswith("_"):
setattr(newobj, i, getattr(obj, i))
return newobj
def _check_allowed_keys(val):
if val not in ["ip", "port", "domain", "scheme"]:
raise InvalidOptionException(
"Provided type 'type' must be 'ip', 'port', 'domain' or 'scheme'")
def _check_allowed_lists(val):
if val not in ["whitelist", "blacklist"]:
raise InvalidOptionException(
"Provided list 'list' must be 'whitelist' or 'blacklist'")
class Options(object):
"""
This object contains configuration options for safeurl.
"""
def __init__(self):
self._follow_location = False
self._follow_location_limit = 0
self._send_credentials = False
self._pin_dns = False
self._lists = {
"whitelist": {
"ip": [],
"port": ["80", "443", "8080"],
"domain": [],
"scheme": ["http", "https"]},
"blacklist": {
"ip": ["0.0.0.0/8", "10.0.0.0/8", "100.64.0.0/10",
"127.0.0.0/8", "169.254.0.0/16",
"172.16.0.0/12", "192.0.0.0/29", "192.0.2.0/24",
"192.88.99.0/24", "192.168.0.0/16",
"198.18.0.0/15", "198.51.100.0/24",
"203.0.113.0/24", "224.0.0.0/4", "240.0.0.0/4"],
"port": [],
"domain": [],
"scheme": []}
}
def getFollowLocation(self):
"""
Get followLocation
:rtype: bool
"""
return self._follow_location
def enableFollowLocation(self):
"""
Enables following redirects
:rtype: :class:`Options`
"""
self._follow_location = True
return self
def disableFollowLocation(self):
"""
Disable following redirects
:rtype: :class:`Options`
"""
self._follow_location = False
return self
def getFollowLocationLimit(self):
"""
Gets the follow location limit
0 is no limit (infinite)
:rtype: int
"""
return self._follow_location_limit
def setFollowLocationLimit(self, limit):
"""
Set follow location limit
0 is no limit (unlimited)
:rtype: int
"""
if not isinstance(limit, Number) or limit < 0:
raise InvalidOptionException(
"Provided limit 'limit' must be an integer >= 0")
self._follow_location_limit = limit
return self
def getSendCredentials(self):
"""
Get send credentials option
:rtype: bool
"""
return self._send_credentials
def enableSendCredentials(self):
"""
Enable sending of credentials
:rtype: :class:`Options`
"""
self._send_credentials = True
return self
def disableSendCredentials(self):
"""
Disable sending of credentials
:rtype: :class:`Options`
"""
self._send_credentials = False
return self
def getPinDns(self):
"""
Get pin DNS option
:rtype: bool
"""
return self._pin_dns
def enablePinDns(self):
"""
Enable pin DNS option
:rtype: :class:`Options`
"""
self._pin_dns = True
return self
def disablePinDns(self):
"""
Disable pin DNS option
:rtype: :class:`Options`
"""
self._pin_dns = False
return self
def isInList(self, lst, type_, value):
"""
Checks if a specific value is in a list
:param arg1: Options: "whitelist" or "blacklist"
:type arg1: string
:param arg2: Options: "ip", "port", "domain", or "scheme"
:type arg2: string
:param arg3: Value to check for
:type arg3: string
:rtype: bool
"""
_check_allowed_lists(lst)
_check_allowed_keys(type_)
dst = self._lists[lst][type_]
if len(dst) == 0:
if lst == "whitelist":
return True
else:
return False
# For domains, a regex match is needed
if type_ == "domain":
for domain in dst:
if re.match("(?i)^%s" % domain, value) is not None:
return True
return False
else:
return value in dst
def getList(self, lst, type_=None):
""""
Returns a specific list
:param arg1: Options: "blacklist" or "whitelist"
:type arg1: string
:param arg2: Type (Optional) - Options: "ip", "port", "domain", or "scheme"
:type arg2: string
:rtype: list
"""
_check_allowed_lists(lst)
dst = self._lists[lst]
if type_ != None:
_check_allowed_keys(type_)
return dst[type_]
return dst
def setList(self, lst, values, type_=None):
"""
Sets a list to be passed in as dictionary
:param arg1: Options: "blacklist" or "whitelist"
:type arg1: string
:param arg2: dictionary to be passed in
:type arg2: dict
:param arg3: Type (Optional) - Options: "ip", "port", "domain", or "scheme"
:type arg3: string
:rtype: :class:`Options`
"""
_check_allowed_lists(lst)
if type_ is not None:
if not isinstance(values, list):
raise InvalidOptionException("Provided values must be a list")
_check_allowed_keys(type_)
self._lists[lst][type_] = values
return self
if not isinstance(values, dict):
raise InvalidOptionException(
"Provided values must be a dictionary")
for k, v in values.iteritems():
_check_allowed_keys(k)
self._lists[lst][k] = v
return self
def clearList(self, lst):
"""
Clears specified list
:param arg1: Options: "blacklist" or "whitelist"
:type arg1: string
"""
_check_allowed_lists(lst)
self._lists[lst] = {"ip": [], "domain": [], "port": [], "scheme": []}
def addToList(self, lst, type_, values):
"""
Add value(s) to a specific list
:param arg1: Options: "blacklist" or "whitelist"
:type arg1: string
:param arg2: Options: "ip", "domain", "port", or "scheme"
:type arg2: string
:param arg3: values to add
:type arg3: string/list (string)
:rtype: :class:`Options`
"""
_check_allowed_lists(lst)
_check_allowed_keys(type_)
if len(values) == 0:
raise InvalidOptionException("Provided values cannot be empty")
if not isinstance(values, list):
values = list(values)
dst = self._lists[lst][type_]
for v in values:
if not v in dst:
dst.append(v)
return self
def removeFromList(self, lst, type_, values):
"""
Remove value(s) from a specific list
:param arg1: Option: "blacklist" or "whitelist"
:type arg1: string
:param arg2: Options: "ip", "domain", "port", or "scheme"
:type arg2: string
:param arg3: values to remove
:type arg3: string/list(string)
:rtype: :class:`Options`
"""
_check_allowed_lists(lst)
_check_allowed_keys(type_)
if len(values) == 0:
raise InvalidOptionException("Provided values cannot be empty")
if not isinstance(values, list):
values = [values]
dst = self._lists[lst][type_]
self._lists[lst][type_] = [x for x in dst if x not in values]
return self
class Url(object):
"""
Class for handling URLs
"""
@staticmethod
def validateUrl(url, options):
"""
Validates the whole URL
:param arg1: The URL
:type arg1: string
:param arg2: Options object
:type arg2: :class:`Options`
:rtype: dict
"""
if len(url) == 0:
raise InvalidURLException("Provided URL 'url' cannot be empty")
# Split URL into parts first
parts = _mutable(urlparse(url))
if parts is None:
raise InvalidURLException("Error parsing URL 'url'")
if parts.hostname is None:
raise InvalidURLException(
"Provided URL 'url' doesn't contain a hostname")
# First, validate the scheme
if len(parts.scheme) != 0:
parts.scheme = Url.validateScheme(parts.scheme, options)
else:
# Default to http
parts.scheme = "http"
# Validate the port
if not parts.port is None:
parts.port = Url.validatePort(parts.port, options)
# Reolve host to ip(s)
parts.ips = Url.resolveHostname(parts.hostname)
# Validate the host
parts.hostname = Url.validateHostname(
parts.hostname, parts.ips, options)
if options.getPinDns():
# Since we"re pinning DNS, we replace the host in the URL
# with an IP, then get cURL to send the Host header
parts.hostname = parts.ips[0]
# Rebuild the URL
cleanUrl = Url.buildUrl(parts)
return {"originalUrl": str(url),
"cleanUrl": str(cleanUrl), "parts": parts}
@staticmethod
def validateScheme(scheme, options):
"""
Validates a URL scheme
:param arg1: scheme
:type arg1: string
:param arg2: Options object
:type arg2: :class:`Object`
:rtype: string
"""
# Whitelist always takes precedence over a blacklist
if not options.isInList("whitelist", "scheme", scheme):
raise InvalidSchemeException("Provided scheme 'scheme' doesn't \
match whitelisted values: %s" % (
", ".join(options.getList("whitelist", "scheme"))))
if options.isInList("blacklist", "scheme", scheme):
raise InvalidSchemeException(
"Provided scheme 'scheme' matches a blacklisted value")
# Existing value is fine
return scheme
@staticmethod
def validatePort(port, options):
"""
Validates a port
:param arg1: port
:type arg1: int
:param arg2: Options object
:type arg2: :class:`Options`
:rtype: int
"""
if not options.isInList("whitelist", "port", port):
raise InvalidPortException("Provided port 'port' doesn't match \
whitelisted values: %s" % (
", ".join(options.getList("whitelist", "port"))))
if options.isInList("blacklist", "port", port):
raise InvalidPortException(
"Provided port 'port' matches a blacklisted value")
# Existing value is fine
return port
@staticmethod
def validateHostname(hostname, ips, options):
"""
Validates a URL hostname
:param arg1: hostname
:type arg1: string
:param arg2: IP addresses to validate
:type arg2: list (string)
:param arg3: Options object
:type arg3: :class:`Options`
:rtype: string
"""
# Check the host against the domain lists
if not options.isInList("whitelist", "domain", hostname):
raise InvalidDomainException("Provided hostname 'hostname' doesn't match \
whitelisted values: %s" % (
", ".join(options.getList("whitelist", "domain"))))
if options.isInList("blacklist", "domain", hostname):
raise InvalidDomainException(
"Provided hostname 'hostname' matches a blacklisted value")
whitelistedIps = options.getList("whitelist", "ip")
if len(whitelistedIps) != 0:
has_match = any(Url.cidrMatch(ip, wlip)
for ip in ips for wlip in whitelistedIps)
if not has_match:
raise InvalidIPException("Provided hostname 'hostname' \
resolves to '%s', which doesn't match whitelisted values: %s"
% (", ".join(ips),
", ".join(whitelistedIps)))
blacklistedIps = options.getList("blacklist", "ip")
if len(blacklistedIps) != 0:
has_match = any(Url.cidrMatch(ip, blip)
for ip in ips for blip in blacklistedIps)
if has_match:
raise InvalidIPException("Provided hostname 'hostname' \
resolves to '%s', which matches a blacklisted value: %s" % (
", ".join(ips), blacklistedIps))
return hostname
@staticmethod
def buildUrl(parts):
"""
Rebuild a URL based on a :func:`_mutable()` object of parts
:param arg1: object of parts
:type arg1: :func:`_mutable()` object
:rtype: string
"""
url = []
if len(parts.scheme) != 0:
url.append("%s://" % parts.scheme)
if not parts.username is None:
url.append(quote(parts.username))
if not parts.password is None:
url.append(":%s" % quote(parts.password))
# If we have a user or pass, make sure to add an "@"
if (not parts.username is None) or (not parts.password is None):
url.append("@")
if not parts.hostname is None:
url.append(parts.hostname)
if not parts.port is None:
url.append(":%d" % int(parts.port))
if len(parts.path) != 0:
url.append("/%s" % quote(parts.path[1:]))
# The query string is difficult to encode properly
# We need to ensure no special characters can be
# used to mangle the URL, but URL encoding all of it
# prevents the query string from being parsed properly
if len(parts.query) != 0:
query = quote(parts.query)
# Replace encoded &, =, ;, [ and ] to originals
query = query.replace("%26", "&").replace("%3D", "=").replace(
"%3B", ";").replace("%5B", "[").replace("%5D", "]")
url.append("?")
url.append(query)
if len(parts.fragment) != 0:
url.append("#%s" % quote(parts.fragment))
return "".join(url)
@staticmethod
def resolveHostname(hostname):
"""
Resolve a hostname to its IP(s)
:param arg1: hostname
:type arg1: string
:rtype: list (string)
"""
try:
ips = gethostbyname_ex(hostname)
return ips[2]
except:
raise InvalidDomainException(
"Provided hostname 'hostname' doesn't \
to an IP address")
@staticmethod
def cidrMatch(ip, cidr):
"""
Checks a passed in IP against a CIDR
:param arg1: IP address
:type arg1: string
:param arg2: CIDR
:type arg2: string
:rtype: bool
"""
return netaddr.IPAddress(ip) in netaddr.IPNetwork(cidr)
class SafeURL(object):
"""
Core interface of module
"""
def __init__(self, handle=None, options=None):
self.setCurlHandle(handle)
if options == None:
options = Options()
self.setOptions(options)
# To start with, disable FOLLOWLOCATION since we'll handle it
self._handle.setopt(pycurl.FOLLOWLOCATION, False)
# Force IPv4, since this class isn't yet compatible with IPv6
self._handle.setopt(pycurl.IPRESOLVE, pycurl.IPRESOLVE_V4)
def getCurlHandle(self):
"""
Returns cURL Handle
:rtype: :class:`SafeURL`
"""
return self._handle
def setCurlHandle(self, handle):
"""
Sets cURL handle
:param arg1: handle
:type arg1: (Optional) :class:`pycurl.Curl` object
:rtype: :class:`pycurl.Curl` object
"""
if handle is None:
handle = pycurl.Curl()
# TODO: Fix this hack!
if repr(handle).find("pycurl.Curl") == -1:
raise Exception("SafeURL expects a valid cURL object!")
self._handle = handle
def getOptions(self):
"""
Gets Options
:rtype: :class:`Options`
"""
return self._options
def setOptions(self, options):
"""
Sets options
:param arg1: Options object
:type: :class:`Options` object
:rtype: :class:`Options` object
"""
self._options = options
def execute(self, url):
"""
Executes a cURL request, whilst checking that the URL abides by our whitelists/blacklists
:param arg1: URL
:type arg1: string
:rtype: string
"""
# Backup the existing URL
originalUrl = url
# Execute, catch redirects and validate the URL
redirected = False
redirectCount = 0
redirectLimit = self._options.getFollowLocationLimit()
followLocation = self._options.getFollowLocation()
while True:
# Validate the URL
url = Url.validateUrl(url, self._options)
# Are there credentials, but we don"t want to send them?
if not self._options.getSendCredentials() and \
(url["parts"].username is not None or
url["parts"].password is not None):
raise InvalidURLException(
"Credentials passed in but 'sendCredentials' \
is set to false")
if self._options.getPinDns():
# Send a Host header
self._handle.setopt(pycurl.HTTPHEADER, [
"Host: %s" % url["parts"].hostname])
# The "fake" URL
self._handle.setopt(pycurl.URL, url["cleanUrl"])
# We also have to disable SSL cert verification, which is not great
# Might be possible to manually check the certificate
# ourselves?
self._handle.setopt(pycurl.SSL_VERIFYPEER, False)
else:
self._handle.setopt(pycurl.URL, url["cleanUrl"])
# Execute the cURL request
response = StringIO.StringIO()
self._handle.setopt(pycurl.WRITEFUNCTION, response.write)
self._handle.perform()
# Check for an HTTP redirect
if followLocation:
statuscode = self._handle.getinfo(pycurl.HTTP_CODE)
if statuscode in [301, 302, 303, 307, 308]:
redirectCount += 1
if redirectLimit == 0 or redirectCount < redirectLimit:
# Redirect received, so rinse and repeat
url = self._handle.getinfo(pycurl.REDIRECT_URL)
redirected = True
else:
raise Exception("Redirect limit 'redirectLimit' hit")
else:
redirected = False
if not redirected:
break
return response.getvalue()