Hi Bob,
Adding build-dev.
On 26/02/2020 6:37 am, Bob Vandette wrote:
Please review this RFE that alters the visibility of JNI entrypoints to hidden
when a shared library
is created using static JDK libraries.
RFE:
https://bugs.openjdk.java.net/browse/JDK-8239563
WEBREV:
http://cr.openjdk.java.net/~bobv/8239563/webrev.00/
CSR:
https://bugs.openjdk.java.net/browse/JDK-8239791
All JNI entrypoints that exist in JDK static libraries are declared as exported
or visible.
If a dynamic library is built from these static libraries, we end up with many
exported
functions that we don't want to provide access to,
This RFE will change the definition of JNIEXPORT for libraries built when
JNI_STATIC_BUILD
is defined. When defined, functions declared with JNIEXPORT will not be
exported when
linked into shared or dynamic libraries. This will still allow linking of
these functions into
dynamic libraries but will not export the JDK symbols outside of the shared
library.
A CSR has been filed (https://bugs.openjdk.java.net/browse/JDK-8239791) to add
the JNI_STATIC_BUILD
define support in jni.h.
I have reservations about turning this into something we have to expose
and support, rather than being something totally handled within the
OpenJDK build system. I'm tempted to suggest the header files be
adjusted to have:
#ifndef JNIEXPORT
<JNIEXPORT basic definitions as they are now >
#endif
and then we define the modified JNIEXPORT via the build system when
doing a static build.
Is that feasible?
Thanks,
David
BACKGROUND:
In JDK8 the JNI specification and JDK implementation was enhanced to support
static JNI libraries
but we didn’t consider the issue of exportibility of JNI entrypoint symbols.
https://bugs.openjdk.java.net/browse/JDK-8005716
If developers use these static JDK libraries in order to produce a custom
shared library, all of the
JNIEXPORTS will be exposed by this library even if the developer did not choose
to export these.
This is a security issue and a potential problem if this library is mixed with
other libraries containing
these symbols.
Bob.
