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<p>Apologies for multiple earlier emails, please ignore and read
this instead.</p>
<p>This proposal is about stripping out and simplifying as much of
the dilapidated and complex SecurityManager infrastructure as
possible, while retaining the ability for developers to implement
a better high scaling and performant Authorization layer, without
prohibitively preventing it.<br>
</p>
<p>Summary of Proposed Changes:</p>
<ol>
<li>GuardFactory & GuardFactorySpi to provide hooks for
authorization checks without SecurityManager or Policy. (Note
GuardFactory should never return null and instead return a no-op
Guard that hotspot can optimize out.<br>
</li>
<li>Existing Permission implementations to be obtained using
GuardFactorySpi implementations, until their removal. Note that
when SecurityManager is stubbed out and Permission
implementations are deprecated for removal, these should no
longer be provided by default, but instead need to be enabled by
entries in the java.security config file, in preparation for
their removal.<br>
</li>
<li>JDK code to no longer call Permission implementations
directly, instances obtained using GuardFactory, when enabled in
the java.security configuration file.<br>
</li>
<li>Threads (system and virtual) updated to use a singleton
*unprivileged* AccessControlContext, instead of inherited
AccessControlContext, this is more appropriate for Executors,
the original inherited context was designed before Executors
were introduced.</li>
<li>Deprecation for removal of all Permission implementations from
the JDK platform. The existing implementations of Permission
introduce unnecessary complexity; they lack sufficient
flexibility resulting in a proliferation of Permission grants
required in policy files and some make blocking network calls.<br>
</li>
<li>Introduce a system property to change AccessController's
default behaviour, disable the stack walk by default, but allow
it to be re-enabled with a system property, replace the stack
walk array result of ProtectionDomains with an *unprivileged*
AccessControlContext, the SubjectDomainCombiner can replace it
with a, AccessControlContext containing a single element array,
containing one ProtectionDomain with Principals. <br>
</li>
<li>AccessController::doPrivileged erases the DomainCombiner by
default, deprecate these methods for removal (make private),
retain doPrivilegedWithCombiner methods that preserve the
SubjectDomainCombiner. Developers should replace their
doPrivileged methods with doPrivilegedWithCombiner. Create a
new method AccessController::doUnprivileged, clear intent, to
erase the DomainCombiner, and use the *unprivileged*
AccessControlContext. Update
AccessController.AccHolder.innocuousAcc to refer to an
*unprivileged* context, as per the definition below.<br>
</li>
<li>Deprecate for removal the CodeSource::implies method.</li>
<li>Give unique ProtectionDomain's with a meaninful CodeSource to
Java modules mapped to the boot loader, rather than using a
Shared ProtectionDomain with a null CodeSource.</li>
<li>Deprecate for removal AccessController::checkPermission and
AccessControlContext::checkPermission methods.</li>
<li>Undeprecate AccessController, AccessControlContext,
DomainCombiner, SubjectDomainCombiner and Subject::doAs methods,
while deprecating for removal methods stated in items above.</li>
<li>Deprecate for removal ProtectionDomain::implies,
ProtectionDomain::getPermissions and
ProtectionDomain::staticPermissionsOnly</li>
<li>Replace PermissionCollection type argument with Object in
ProtectionDomain constructors, ignore the permissions parameter,
and deprecate existing constructors. Deprecate
PermissionCollection for removal.<br>
</li>
<li>Create a new constructor: ProtectionDomain(CodeSource cs,
ClassLoader cl, Principal[] p).</li>
<li>Create a new factory method
ProtectionDomain::newInstance(Principal[] p), to allow a weak
cache of ProtectionDomain instances for each Principal[], to be
utilised by SubjectDomainCombiner to avoid unnecessary
duplication of objects. This is an optimization for
AccessControlContext::equals and ::hashCode methods. Using a
cache of AccessControlContext, it is possible to avoid
rechecking authorization that has already been checked. For
example, when using an Executor with many tasks, all with the
same AccessControlContext, you only need to check once and
return the same result for subsequent checks. This is an
optimization I have used previously to great effect.<br>
</li>
</ol>
<p>To clarify what an *unprivileged* AccessControlContext is:</p>
<blockquote>
<p>An instance of AccessControlContext, that contains a single
element array, containing a ProtectionDomain, with a null
ClassLoader, null Principal[] and a *non-null* CodeSource,
containing a null URL.<br>
</p>
<p>So as to distinguish between what is traditionally a JDK
bootstrap ProtectionDomain and unprivileged domain after
ProtectionDomain::getPermissions is removed.<br>
</p>
</blockquote>
<blockquote> </blockquote>
<p>Stubbing of SecurityManager and Policy, for runtime backward
compatibility. Update ProtectionDomain::implies method, to *not*
consult with the Policy. Note it's possible to get access to the
ProtectionDomain array contained within AccessControlContext using
a DomainCombiner.<br>
</p>
<p>This is backward compatible with existing usages of JAAS and
least painful method of transition for all concerned as well as
allowing complete flexibility of implementation.</p>
<p>Regards,</p>
<p>Peter Firmstone.<br>
</p>
<div class="moz-cite-prefix">On 25/06/2021 3:59 pm, Peter Firmstone
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:2f315680-1cdb-1694-34a3-95312bf42ca7@zeus.net.au">Thanks
Dalibor, <br>
<br>
Would targeting Java 18 be practical? <br>
<br>
Also it won't take long to code a prototype, just not sure of the
process. <br>
<br>
Cheers, <br>
<br>
Peter. <br>
<br>
<br>
On 24/06/2021 9:30 pm, Dalibor Topic wrote: <br>
<blockquote type="cite">On 24.06.2021 04:24, Peter Firmstone
wrote: <br>
<blockquote type="cite">Thanks Andrew, <br>
<br>
For the simple case, of replacing the SecurityManager stack
walk, one could use reflection. <br>
<br>
Thank you for also confirming that is not possible (or at
least very unlikely) to add a GuardBuilder to Java 8, the
proposal is for JDK code to use a provider mechanism, to
intercept permission checks, so custom authentication layers
can be implemented, this could be accepted in future versions
of Java, but not existing. As it is said, there is no harm in
asking. <br>
</blockquote>
<br>
Generally speaking, adding any public APIs to a platform release
after its specification has been published, is always going to
be a very tall order involving the JCP, among other things. It's
not really worth it, when other technical solutions, such as
multi-release JARs, already exist, that alleviate the necessity.
<br>
<br>
cheers, <br>
dalibor topic <br>
<br>
</blockquote>
</blockquote>
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