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8217920: Lookup.defineClass injects a class that can access private members of any class in its own module

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Reviewed-by: psandoz, alanb, darcy
This commit is contained in:
Mandy Chung 2023-01-27 18:31:03 +00:00
parent 22c976a9b0
commit 7f05d57a87
2 changed files with 31 additions and 1 deletions
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18
src/java.base/share/classes/java/lang/Module.java
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@ -597,6 +597,14 @@ public final class Module implements AnnotatedElement {
*
* <p> This method does not check if the given module reads this module. </p>
*
* @apiNote A package {@code p} opened to module {@code M} allows code in
* {@code M} do {@linkplain java.lang.reflect.AccessibleObject#setAccessible(boolean)
* deep reflection} on all types in the package.
* Further, if {@code M} reads this module, it can obtain a
* {@link java.lang.invoke.MethodHandles.Lookup Lookup} object that is allowed to
* {@link java.lang.invoke.MethodHandles.Lookup#defineClass(byte[]) define classes}
* in package {@code p}.
*
* @param pn
* The package name
* @param other
@ -650,6 +658,14 @@ public final class Module implements AnnotatedElement {
*
* <p> This method does not check if the given module reads this module. </p>
*
* @apiNote A package {@code p} opened to module {@code M} allows code in
* {@code M} do {@linkplain java.lang.reflect.AccessibleObject#setAccessible(boolean)
* deep reflection} on all types in the package.
* Further, if {@code M} reads this module, it can obtain a
* {@link java.lang.invoke.MethodHandles.Lookup Lookup} object that is allowed to
* {@link java.lang.invoke.MethodHandles.Lookup#defineClass(byte[]) define classes}
* in package {@code p}.
*
* @param pn
* The package name
*
@ -657,6 +673,8 @@ public final class Module implements AnnotatedElement {
* unconditionally
*
* @see ModuleDescriptor#opens()
* @see java.lang.reflect.AccessibleObject#setAccessible(boolean)
* @see java.lang.invoke.MethodHandles#privateLookupIn
*/
public boolean isOpen(String pn) {
Objects.requireNonNull(pn);

14
src/java.base/share/classes/java/lang/invoke/MethodHandles.java
View file

@ -233,6 +233,12 @@ public class MethodHandles {
* <p>
* The resulting {@code Lookup} object has no {@code ORIGINAL} access.
*
* @apiNote The {@code Lookup} object returned by this method is allowed to
* {@linkplain Lookup#defineClass(byte[]) define classes} in the runtime package
* of {@code targetClass}. Extreme caution should be taken when opening a package
* to another module as such defined classes have the same full privilege
* access as other members in {@code targetClass}'s module.
*
* @param targetClass the target class
* @param caller the caller lookup object
* @return a lookup object for the target class, with private access
@ -851,7 +857,7 @@ public class MethodHandles {
* <p>
* {@link MethodHandles#privateLookupIn(Class, Lookup) MethodHandles.privateLookupIn(T.class, lookup)}
* can be used to teleport a {@code lookup} from class {@code C} to class {@code T}
* and create a new {@code Lookup} with <a href="#privacc">private access</a>
* and produce a new {@code Lookup} with <a href="#privacc">private access</a>
* if the lookup class is allowed to do <em>deep reflection</em> on {@code T}.
* The {@code lookup} must have {@link #MODULE} and {@link #PRIVATE} access
* to call {@code privateLookupIn}.
@ -869,6 +875,12 @@ public class MethodHandles {
* it cannot be used to obtain another private {@code Lookup} by calling
* {@link MethodHandles#privateLookupIn(Class, Lookup) privateLookupIn}
* because it has no {@code MODULE} access.
* <p>
* The {@code Lookup} object returned by {@code privateLookupIn} is allowed to
* {@linkplain Lookup#defineClass(byte[]) define classes} in the runtime package
* of {@code T}. Extreme caution should be taken when opening a package
* to another module as such defined classes have the same full privilege
* access as other members in {@code M2}.
*
* <h2><a id="module-access-check"></a>Cross-module access checks</h2>
*