Re: RFR: 8155775: Re-examine naming of privileged methods to access System properties

[Sean Mullan]

On 5/9/16 11:44 PM, Wang Weijun wrote:
I have a question related.

There are some places in JDK that use doPrivileged to read "os.name" etc. This 
system property is in the default java.policy file
On May 2, 2016, at 10:15 PM, Sean Mullan <sean.mul...@oracle.com> wrote:

This is not an issue in your changes, but the current javadoc for 
Version.current() says:

266      * @throws  SecurityException
267      *          If a security manager exists and its {@link
268      *          SecurityManager#checkPropertyAccess(String)
269      *          checkPropertyAccess} method does not allow access to the
270      *          system property "java.version"

but this can never occur since the code is wrapping the call to 
System.getProperty("java.version") in doPrivileged, so the caller's permissions 
are never checked.

I think that this is a bug in the javadoc of this method and that it should not be 
specified to throw SecurityException. All code already has permission to read 
"java.version" in the default java.policy file.

Can you clarify?

If a system property is listed in the default java.policy file, shall we use or 
not use doPrivileged() to read it inside JDK? I thought the answer is yes 
because the policy file could be modified.

Yes, you should use doPrivileged in that case, since the policy can be 
modified so you don't necessarily know that the caller has permission to 
read that property. System.getProperty will still perform a security check.

--Sean