Chez Online, l’accès KVM nécessite parfois l’execution d’un code java via icedtea-web. Pour certains vieux serveurs, un erreur Cannot grant permissions to unsigned jars doit être résolue.

$ javaws viewer.jnlp
netx: Initialization Error: Could not initialize application. (Fatal: Application Error: Cannot grant permissions to unsigned jars. Application requested security permissions, but jars are not signed.)
net.sourceforge.jnlp.LaunchException: Fatal: Initialization Error: Could not initialize application. The application has not been initialized, for more information execute javaws from the command line.
	at java.desktop/net.sourceforge.jnlp.Launcher.createApplication(Launcher.java:823)
	at java.desktop/net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:531)
	at java.desktop/net.sourceforge.jnlp.Launcher$TgThread.run(Launcher.java:946)
Caused by: net.sourceforge.jnlp.LaunchException: Fatal: Application Error: Cannot grant permissions to unsigned jars. Application requested security permissions, but jars are not signed.
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader$SecurityDelegateImpl.getClassLoaderSecurity(JNLPClassLoader.java:2488)
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader.setSecurity(JNLPClassLoader.java:384)
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader.initializeResources(JNLPClassLoader.java:807)
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader.<init>(JNLPClassLoader.java:337)
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader.createInstance(JNLPClassLoader.java:420)
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader.getInstance(JNLPClassLoader.java:494)
	at java.desktop/net.sourceforge.jnlp.runtime.JNLPClassLoader.getInstance(JNLPClassLoader.java:467)
	at java.desktop/net.sourceforge.jnlp.Launcher.createApplication(Launcher.java:815)
	... 2 more

Pour se faire, vous pouvez identifier les jar qui posent problème via la java console :

...
netx: Initialization Error: Could not initialize application. (Fatal: Application Error: Cannot grant permissions to unsigned jars. Application requested security permissions, but jars are not signed.)
App already has trusted publisher: false
Jar found at /home/user/.cache/icedtea-web/cache/3/https/192.168.1.1/443/software/avctVMLinux64.jarhas been verified as UNSIGNED
Jar found at /home/user/.cache/icedtea-web/cache/2/https/192.168.1.1/443/software/avctKVMIOLinux64.jarhas been verified as UNSIGNED
Jar found at /home/user/.cache/icedtea-web/cache/1/https/192.168.1.1/443/software/avctKVM.jarhas been verified as UNSIGNED

On peut reproduire l’erreur via l’outil jarsigner :

$ jarsigner -verify -certs -verbose /home/user/.cache/icedtea-web/cache/3/https/192.168.1.1/443/software/avctVMLinux64.jar

        196 Fri Jul 25 17:49:26 CEST 2014 META-INF/MANIFEST.MF
        259 Mon Jul 24 09:53:16 CEST 2017 META-INF/DELL.SF
        6669 Mon Jul 24 09:53:16 CEST 2017 META-INF/DELL.RSA
         259 Fri Jul 25 17:49:26 CEST 2014 META-INF/AVOCENT.SF
        1058 Fri Jul 25 17:49:26 CEST 2014 META-INF/AVOCENT.DSA
           0 Tue Nov 05 14:49:36 CET 2013 META-INF/
 m  ? 371353 Tue May 17 15:52:22 CEST 2011 libavmlinux.so

  s = signature was verified 
  m = entry is listed in manifest
  k = at least one certificate was found in keystore
  ? = unsigned entry

- Signed by "CN=Avocent, OU=iBMC, O=Avocent Corporation, L=Sunrise, ST=Florida, C=US"
    Digest algorithm: SHA1 (disabled)
    Signature algorithm: SHA1withDSA (disabled), 1024-bit key (weak)
- Signed by "CN=Dell Inc., O=Dell Inc., L=Round Rock, ST=Texas, C=US"
    Digest algorithm: SHA1 (weak)
    Signature algorithm: MD5withRSA (disabled), 2048-bit key
  Timestamped by "CN=Certum EV TSA SHA2, OU=Certum Certification Authority, O=Unizeto Technologies S.A., C=PL" on lun. juil. 24 09:53:17 UTC 2017
    Timestamp digest algorithm: SHA-1 (weak)
    Timestamp signature algorithm: SHA256withRSA, 2048-bit key

WARNING: The jar will be treated as unsigned, because it is signed with a weak algorithm that is now disabled by the security property:

  jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024, DSA keySize < 1024, SHA1 denyAfter 2019-01-01

Il faut donc intervenir sur l’option jdk.jar.disabledAlgorithms de java pour réactiver les éléments désactivés par défaut. Ici SHA1 (et par incidence SHA1withDSA et MD5withRSA).

Pour le faire, il faut éditer le fichier java.security de la version de votre java.

La version de mon java étant 17.0.5 :

$ java -version
openjdk version "17.0.5" 2022-10-18
OpenJDK Runtime Environment (build 17.0.5+8-Debian-2)
OpenJDK 64-Bit Server VM (build 17.0.5+8-Debian-2, mixed mode, sharing)

je modifie la configuration de la version 17.0 qui se trouve dans /usr/lib/jvm/java-1.17.0-openjdk-amd64/conf/security/java.security :

#jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024, DSA keySize < 1024, SHA1 denyAfter 2019-01-01
jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024, DSA keySize < 1024

jarsigner indique maintenant que le jar est vérifié :

$ jarsigner -verify -certs -verbose /home/user/.cache/icedtea-web/cache/3/https/192.168.1.1/443/software/avctVMLinux64.jar
...

jar verified.

et icedtea-web ne pose plus de problème :

$ javaws viewer.jnlp