jbonofre commented on code in PR #2870:
URL: https://github.com/apache/karaf/pull/2870#discussion_r3991000916
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services/interceptor/impl/src/main/java/org/apache/karaf/service/interceptor/impl/runtime/proxy/AsmProxyFactory.java:
##########
@@ -114,19 +114,31 @@ private boolean hasSameSignature(Method a, Method b) {
private void createConstructor(final ClassWriter cw, final String
proxyClassFileName, final Class<?> classToProxy,
final String classFileName) {
- Constructor superDefaultCt;
- String parentClassFileName = classFileName;
- String descriptor = "()V";
-
- try {
- if (classToProxy.isInterface()) {
- parentClassFileName = Type.getInternalName(Object.class);
- superDefaultCt = Object.class.getConstructor(null);
- descriptor = Type.getConstructorDescriptor(superDefaultCt);
+ // the proxy extends the proxied class, or Object when proxying an
interface; either way
+ // the super constructor it invokes is the no-arg one
+ final String parentClassFileName;
+ if (classToProxy.isInterface()) {
+ parentClassFileName = Type.getInternalName(Object.class);
+ } else {
+ parentClassFileName = classFileName;
+ // without these checks the generated INVOKESPECIAL would only
fail once the proxy is
+ // instantiated. The proxy is defined by its own class loader, so
it lands in a different
+ // runtime package than the proxied class: only a public or
protected constructor is
+ // reachable from it, a package-private one is not.
+ final Constructor<?> superCt;
+ try {
+ superCt = classToProxy.getDeclaredConstructor();
+ } catch (final NoSuchMethodException nsme) {
+ throw new IllegalArgumentException("Cannot proxy " +
classToProxy.getName()
+ + ", it has no no-arg constructor", nsme);
+ }
+ final int modifiers = superCt.getModifiers();
+ if (!Modifier.isPublic(modifiers) &&
!Modifier.isProtected(modifiers)) {
Review Comment:
This only checks the constructor own modifiers, not whether `classToProxy`
itself is accessible to a class defined by a different `ClassLoader`. A
package-private class (common for OSGi impl classes) with a public/protected
no-arg constructor passes this check, but the proxy (defined by its own
`ProxyClassLoader`, hence a different runtime package even with an identical
package name) still can't legally extend it.
That fails later with an uncaught `IllegalAccessError` at class-link time,
which is exactly the failure mode this PR set out to prevent.
I suggest also checking `Modifier.isPublic(classToProxy.getModifiers())`
here. Thoughts?
##########
services/interceptor/impl/src/main/java/org/apache/karaf/service/interceptor/impl/runtime/proxy/AsmProxyFactory.java:
##########
@@ -114,19 +114,31 @@ private boolean hasSameSignature(Method a, Method b) {
private void createConstructor(final ClassWriter cw, final String
proxyClassFileName, final Class<?> classToProxy,
final String classFileName) {
- Constructor superDefaultCt;
- String parentClassFileName = classFileName;
- String descriptor = "()V";
-
- try {
- if (classToProxy.isInterface()) {
- parentClassFileName = Type.getInternalName(Object.class);
- superDefaultCt = Object.class.getConstructor(null);
- descriptor = Type.getConstructorDescriptor(superDefaultCt);
+ // the proxy extends the proxied class, or Object when proxying an
interface; either way
+ // the super constructor it invokes is the no-arg one
+ final String parentClassFileName;
+ if (classToProxy.isInterface()) {
+ parentClassFileName = Type.getInternalName(Object.class);
+ } else {
+ parentClassFileName = classFileName;
+ // without these checks the generated INVOKESPECIAL would only
fail once the proxy is
+ // instantiated. The proxy is defined by its own class loader, so
it lands in a different
+ // runtime package than the proxied class: only a public or
protected constructor is
+ // reachable from it, a package-private one is not.
+ final Constructor<?> superCt;
+ try {
+ superCt = classToProxy.getDeclaredConstructor();
Review Comment:
`getDeclaredConstructor()` forces the JVM to resolve **all** declared
constructors of `classToProxy`, not just the no-arg one: previously this branch
never reflected on constructors at all.
If `classToProxy` has an unrelated constructor whose parameter type lives in
an optional/unresolvable OSGi bundle, this now throws an uncaught
`NoClassDefFoundError` where proxying used to just work.
That's a regression risk in exactly the split-classpath environment Karaf
runs in. Worth maybe a test with such a class before merging. Thoughts?
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