util.xml: Do not allow doctypes, comments or processing instructions
Yes. This is as bad as it sounds. CVE pending.
In Prosody itself, this only affects mod_websocket, which uses util.xml
to parse the <open/> frame, thus allowing unauthenticated remote DoS
using Billion Laughs. However, third-party modules using util.xml may
also be affected by this.
This commit installs handlers which disallow the use of doctype
declarations and processing instructions without any escape hatch. It,
by default, also introduces such a handler for comments, however, there
is a way to enable comments nontheless.
This is because util.xml is used to parse human-facing data, where
comments are generally a desirable feature, and also because comments
are generally harmless.
# PEP publish, subscribe and publish-options
[Client] Romeo
jid: pep-test-wjebo4kg@localhost
password: password
[Client] Juliet
jid: pep-test-tqvqu_pv@localhost
password: password
-----
Romeo connects
Romeo sends:
<presence>
<c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/>
</presence>
Romeo receives:
<iq type='get' id='disco' from="${Romeo's JID}">
<query node='http://code.matthewwild.co.uk/verse/#PDH7CGVPRERS2WUqBD18PHGEzaY=' xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
Romeo receives:
<presence from="${Romeo's full JID}">
<c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/>
</presence>
Romeo sends:
<iq type='get' id='6'>
<query ver='' xmlns='jabber:iq:roster'/>
</iq>
Romeo receives:
<iq type='result' id='6'>
<query ver='1' xmlns='jabber:iq:roster'/>
</iq>
Juliet connects
Juliet sends:
<presence>
<c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/>
</presence>
Juliet receives:
<iq type='get' id='disco' from="${Juliet's JID}">
<query node='http://code.matthewwild.co.uk/verse/#PDH7CGVPRERS2WUqBD18PHGEzaY=' xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
Juliet receives:
<presence from="${Juliet's full JID}">
<c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/>
</presence>
Juliet sends:
<iq type='get' id='6'>
<query ver='' xmlns='jabber:iq:roster'/>
</iq>
Juliet receives:
<iq type='result' id='6'>
<query ver='1' xmlns='jabber:iq:roster'/>
</iq>
Romeo sends:
<iq type='result' id='disco' to='pep-test-wjebo4kg@localhost'><query xmlns='http://jabber.org/protocol/disco#info' node='http://code.matthewwild.co.uk/verse/#PDH7CGVPRERS2WUqBD18PHGEzaY='><identity type='pc' name='Verse' category='client'/><feature var='http://jabber.org/protocol/disco#info'/><feature var='http://jabber.org/protocol/disco#items'/><feature var='http://jabber.org/protocol/caps'/></query></iq>
Romeo sends:
<presence type='subscribe' to="${Juliet's JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='set' id='{scansion:any}'><query ver='1' xmlns='jabber:iq:roster'><item ask='subscribe' jid='pep-test-tqvqu_pv@localhost' subscription='none'/></query></iq>
Romeo receives:
<presence type='unavailable' to='pep-test-wjebo4kg@localhost' from='pep-test-tqvqu_pv@localhost'/>
Juliet receives:
<presence type='subscribe' from='pep-test-wjebo4kg@localhost' to='pep-test-tqvqu_pv@localhost'><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Juliet sends:
<iq type='result' id='disco' to='pep-test-tqvqu_pv@localhost'><query xmlns='http://jabber.org/protocol/disco#info' node='http://code.matthewwild.co.uk/verse/#PDH7CGVPRERS2WUqBD18PHGEzaY='><identity type='pc' name='Verse' category='client'/><feature var='http://jabber.org/protocol/disco#info'/><feature var='http://jabber.org/protocol/disco#items'/><feature var='http://jabber.org/protocol/caps'/></query></iq>
Juliet sends:
<presence type='subscribe' to="${Romeo's JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Juliet receives:
<iq type='set' id='{scansion:any}'><query ver='2' xmlns='jabber:iq:roster'><item ask='subscribe' jid='pep-test-wjebo4kg@localhost' subscription='none'/></query></iq>
Juliet receives:
<presence type='unavailable' to='pep-test-tqvqu_pv@localhost' from='pep-test-wjebo4kg@localhost'/>
Romeo receives:
<presence type='subscribe' from='pep-test-tqvqu_pv@localhost' to='pep-test-wjebo4kg@localhost'><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo sends:
<iq type='result' id='fixme'/>
Romeo sends:
<presence type='subscribed' to='pep-test-tqvqu_pv@localhost'><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='set' id='{scansion:any}'><query ver='3' xmlns='jabber:iq:roster'><item ask='subscribe' jid='pep-test-tqvqu_pv@localhost' subscription='from'/></query></iq>
Juliet receives:
<presence type='subscribed' from='pep-test-wjebo4kg@localhost' to='pep-test-tqvqu_pv@localhost'><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Juliet receives:
<iq type='set' id='{scansion:any}'><query ver='3' xmlns='jabber:iq:roster'><item jid='pep-test-wjebo4kg@localhost' subscription='to'/></query></iq>
Juliet receives:
<presence to='pep-test-tqvqu_pv@localhost' from="${Romeo's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/><delay xmlns='urn:xmpp:delay' stamp='{scansion:any}' from='localhost'/></presence>
Juliet sends:
<presence type='subscribed' to='pep-test-wjebo4kg@localhost'><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Juliet receives:
<iq type='set' id='{scansion:any}'><query ver='4' xmlns='jabber:iq:roster'><item jid='pep-test-wjebo4kg@localhost' subscription='both'/></query></iq>
Juliet receives:
<presence to='pep-test-tqvqu_pv@localhost' from="${Romeo's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/><delay xmlns='urn:xmpp:delay' stamp='{scansion:any}' from='localhost'/></presence>
Romeo receives:
<presence type='subscribed' from='pep-test-tqvqu_pv@localhost' to='pep-test-wjebo4kg@localhost'><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='set' id='{scansion:any}'><query ver='4' xmlns='jabber:iq:roster'><item jid='pep-test-tqvqu_pv@localhost' subscription='both'/></query></iq>
Romeo receives:
<presence to='pep-test-wjebo4kg@localhost' from="${Juliet's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='PDH7CGVPRERS2WUqBD18PHGEzaY=' node='http://code.matthewwild.co.uk/verse/'/><delay xmlns='urn:xmpp:delay' stamp='{scansion:any}' from='localhost'/></presence>
Juliet sends:
<iq type='result' id='fixme'/>
Romeo sends:
<iq type='result' id='fixme'/>
Romeo sends:
<iq type='result' id='fixme'/>
Romeo sends:
<presence><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='m/sIsyfzKk8X1okZMtStR43nQQg=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='get' id='disco' from='pep-test-wjebo4kg@localhost'><query node='http://code.matthewwild.co.uk/verse/#m/sIsyfzKk8X1okZMtStR43nQQg=' xmlns='http://jabber.org/protocol/disco#info'/></iq>
Romeo receives:
<presence from="${Romeo's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='m/sIsyfzKk8X1okZMtStR43nQQg=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='get' id='disco' from='pep-test-tqvqu_pv@localhost'><query node='http://code.matthewwild.co.uk/verse/#m/sIsyfzKk8X1okZMtStR43nQQg=' xmlns='http://jabber.org/protocol/disco#info'/></iq>
Juliet receives:
<presence from="${Romeo's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='m/sIsyfzKk8X1okZMtStR43nQQg=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo sends:
<presence><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='IfQwbaaDB4LEP5tkGArEaB/3Y+s=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='get' id='disco' from='pep-test-wjebo4kg@localhost'><query node='http://code.matthewwild.co.uk/verse/#IfQwbaaDB4LEP5tkGArEaB/3Y+s=' xmlns='http://jabber.org/protocol/disco#info'/></iq>
Romeo receives:
<presence from="${Romeo's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='IfQwbaaDB4LEP5tkGArEaB/3Y+s=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Romeo receives:
<iq type='get' id='disco' from='pep-test-tqvqu_pv@localhost'><query node='http://code.matthewwild.co.uk/verse/#IfQwbaaDB4LEP5tkGArEaB/3Y+s=' xmlns='http://jabber.org/protocol/disco#info'/></iq>
Romeo sends:
<iq type='result' id='disco' to='pep-test-wjebo4kg@localhost'><query xmlns='http://jabber.org/protocol/disco#info' node='http://code.matthewwild.co.uk/verse/#m/sIsyfzKk8X1okZMtStR43nQQg='/></iq>
Romeo sends:
<iq type='result' id='disco' to='pep-test-tqvqu_pv@localhost'><query xmlns='http://jabber.org/protocol/disco#info' node='http://code.matthewwild.co.uk/verse/#m/sIsyfzKk8X1okZMtStR43nQQg='/></iq>
Romeo sends:
<iq type='result' id='disco' to='pep-test-wjebo4kg@localhost'><query xmlns='http://jabber.org/protocol/disco#info' node='http://code.matthewwild.co.uk/verse/#IfQwbaaDB4LEP5tkGArEaB/3Y+s='><identity type='pc' name='Verse' category='client'/><feature var='http://jabber.org/protocol/tune+notify'/><feature var='http://jabber.org/protocol/disco#info'/><feature var='http://jabber.org/protocol/disco#items'/><feature var='http://jabber.org/protocol/caps'/><feature var='http://jabber.org/protocol/mood+notify'/></query></iq>
Juliet receives:
<presence from="${Romeo's full JID}"><c xmlns='http://jabber.org/protocol/caps' hash='sha-1' ver='IfQwbaaDB4LEP5tkGArEaB/3Y+s=' node='http://code.matthewwild.co.uk/verse/'/></presence>
Juliet sends:
<iq type='result' id='fixme'/>
Juliet sends:
<iq type='set' id='7'><pubsub xmlns='http://jabber.org/protocol/pubsub'><publish node='http://jabber.org/protocol/tune'><item id='current'><tune xmlns='http://jabber.org/protocol/tune'><title>Beautiful Cedars</title><artist>The Spinners</artist><source>Not Quite Folk</source><track>4</track></tune></item></publish></pubsub></iq>
Juliet receives:
<iq type='result' id='7' ><pubsub xmlns='http://jabber.org/protocol/pubsub'><publish node='http://jabber.org/protocol/tune'><item id='current'/></publish></pubsub></iq>
Juliet sends:
<iq type='set' id='8'><pubsub xmlns='http://jabber.org/protocol/pubsub'><publish node='http://jabber.org/protocol/mood'><item><mood xmlns='http://jabber.org/protocol/mood'><happy/></mood></item></publish><publish-options><x type='submit' xmlns='jabber:x:data'><field type='hidden' var='FORM_TYPE'><value>http://jabber.org/protocol/pubsub#publish-options</value></field><field var='pubsub#persist_items'><value>true</value></field><field var='pubsub#access_model'><value>whitelist</value></field></x></publish-options></pubsub></iq>
Juliet receives:
<iq type='result' id='8'><pubsub xmlns='http://jabber.org/protocol/pubsub'><publish node='http://jabber.org/protocol/mood'><item id='{scansion:any}'/></publish></pubsub></iq>
Juliet sends:
<iq type='result' id='{scansion:any}'/>
Romeo receives:
<message type='headline' from='pep-test-tqvqu_pv@localhost'><event xmlns='http://jabber.org/protocol/pubsub#event'><items node='http://jabber.org/protocol/tune'><item id='current'><tune xmlns='http://jabber.org/protocol/tune'><title>Beautiful Cedars</title><artist>The Spinners</artist><source>Not Quite Folk</source><track>4</track></tune></item></items></event></message>
Romeo sends:
<iq type='result' id='disco' to='pep-test-tqvqu_pv@localhost'><query xmlns='http://jabber.org/protocol/disco#info' node='http://code.matthewwild.co.uk/verse/#IfQwbaaDB4LEP5tkGArEaB/3Y+s='><identity type='pc' name='Verse' category='client'/><feature var='http://jabber.org/protocol/tune+notify'/><feature var='http://jabber.org/protocol/disco#info'/><feature var='http://jabber.org/protocol/disco#items'/><feature var='http://jabber.org/protocol/caps'/><feature var='http://jabber.org/protocol/mood+notify'/></query></iq>
Romeo receives:
<message type='headline' from='pep-test-tqvqu_pv@localhost'><event xmlns='http://jabber.org/protocol/pubsub#event'><items node='http://jabber.org/protocol/tune'><item id='current'><tune xmlns='http://jabber.org/protocol/tune'><title>Beautiful Cedars</title><artist>The Spinners</artist><source>Not Quite Folk</source><track>4</track></tune></item></items></event></message>
Juliet disconnects
Romeo disconnects