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.
.DEFAULT: localhost.crt
keysize=2048
# How to:
# First, `make yourhost.cnf` which creates a openssl config file.
# Then edit this file and fill in the details you want it to have,
# and add or change hosts and components it should cover.
# Then `make yourhost.key` to create your private key, you can
# include keysize=number to change the size of the key.
# Then you can either `make yourhost.csr` to generate a certificate
# signing request that you can submit to a CA, or `make yourhost.crt`
# to generate a self signed certificate.
.PRECIOUS: %.cnf %.key
# To request a cert
%.csr: %.cnf %.key
openssl req -new -key $(lastword $^) \
-sha256 -utf8 -config $(firstword $^) -out $@
%.csr: %.cnf
umask 0077 && touch $*.key
openssl req -new -newkey rsa:$(keysize) -nodes -keyout $*.key \
-sha256 -utf8 -config $^ -out $@
@chmod 400 $*.key
%.csr: %.key
openssl req -new -key $^ -utf8 -subj /CN=$* -out $@
%.csr:
umask 0077 && touch $*.key
openssl req -new -newkey rsa:$(keysize) -nodes -keyout $*.key \
-utf8 -subj /CN=$* -out $@
@chmod 400 $*.key
# Self signed
%.crt: %.cnf %.key
openssl req -new -x509 -key $(lastword $^) -days 365 -sha256 -utf8 \
-config $(firstword $^) -out $@
%.crt: %.cnf
umask 0077 && touch $*.key
openssl req -new -x509 -newkey rsa:$(keysize) -nodes -keyout $*.key \
-days 365 -sha256 -utf8 -config $(firstword $^) -out $@
@chmod 400 $*.key
%.crt: %.key
openssl req -new -x509 -key $^ -days 365 -sha256 -utf8 -subj /CN=$* -out $@
%.crt:
umask 0077 && touch $*.key
openssl req -new -x509 -newkey rsa:$(keysize) -nodes -keyout $*.key \
-days 365 -sha256 -out $@ -utf8 -subj /CN=$*
@chmod 400 $*.key
# Generate a config from the example
%.cnf:
sed 's,example\.com,$*,g' openssl.cnf > $@
%.key:
umask 0077 && openssl genrsa -out $@ $(keysize)
@chmod 400 $@
# Generate Diffie-Hellman parameters
dh-%.pem:
openssl dhparam -out $@ $*