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// ------------------------------------------------------------------------- |
// ------------------------------------------------------------------------- |
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/** |
/** |
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* A mapping between pairs (<i>thread</i>, <i>classname</i>) to access |
* This is a per-thread stack of AccessControlContext objects (which can |
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* control contexts. The <i>thread</i> and <i>classname</i> are the thread |
* be null) for each call to AccessController.doPrivileged in each thread's |
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* and <i>classname</i> current as of the last call to doPrivileged with |
* call stack. We use this to remember which context object corresponds to |
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* an AccessControlContext argument. |
* which call. |
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*/ |
*/ |
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private static final Map contexts = Collections.synchronizedMap(new HashMap()); |
private static final ThreadLocal contexts = new ThreadLocal(); |
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/** |
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* This is a Boolean that, if set, tells getContext that it has already |
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* been called once, allowing us to handle recursive permission checks |
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* caused by methods getContext calls. |
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*/ |
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private static final ThreadLocal inGetContext = new ThreadLocal(); |
private static final ThreadLocal inGetContext = new ThreadLocal(); |
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/** |
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* And we return this all-permissive context to ensure that privileged |
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* methods called from getContext succeed. |
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*/ |
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private final static AccessControlContext DEFAULT_CONTEXT; |
private final static AccessControlContext DEFAULT_CONTEXT; |
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static |
static |
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{ |
{ |
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} |
} |
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private static final boolean DEBUG = false; |
private static final boolean DEBUG = false; |
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private static void debug (String msg) |
private static void debug(String msg) |
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{ |
{ |
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System.err.print (">>> VMAccessController: "); |
System.err.print(">>> VMAccessController: "); |
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System.err.println (msg); |
System.err.println(msg); |
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} |
} |
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// Constructors. |
// Constructors. |
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* pushed from one thread will not be available to another. |
* pushed from one thread will not be available to another. |
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* |
* |
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* @param acc The access control context. |
* @param acc The access control context. |
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* @param clazz The class that implements {@link PrivilegedAction}. |
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*/ |
*/ |
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static void pushContext (AccessControlContext acc, Class clazz) |
static void pushContext (AccessControlContext acc) |
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{ |
{ |
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ArrayList pair = new ArrayList (2); |
if (DEBUG) |
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pair.add (Thread.currentThread()); |
debug("pushing " + acc); |
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pair.add (clazz); |
LinkedList stack = (LinkedList) contexts.get(); |
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if (DEBUG) debug ("pushing " + pair); |
if (stack == null) |
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contexts.put (pair, acc); |
{ |
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stack = new LinkedList(); |
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contexts.set(stack); |
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} |
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stack.addFirst(acc); |
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} |
} |
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/** |
/** |
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* This method is used by {@link AccessController} when exiting from a |
* This method is used by {@link AccessController} when exiting from a |
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* call to {@link |
* call to {@link |
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* AccessController#doPrivileged(java.security.PrivilegedAction,java.security.AccessControlContext)}. |
* AccessController#doPrivileged(java.security.PrivilegedAction,java.security.AccessControlContext)}. |
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* |
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* @param clazz The class that implements {@link PrivilegedAction}. |
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*/ |
*/ |
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static void popContext (Class clazz) |
static void popContext() |
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{ |
{ |
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ArrayList pair = new ArrayList (2); |
if (DEBUG) |
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pair.add (Thread.currentThread()); |
debug("popping context"); |
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pair.add (clazz); |
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if (DEBUG) debug ("popping " + pair); |
// Stack should never be null, nor should it be empty, if this method |
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contexts.remove (pair); |
// and its counterpart has been called properly. |
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LinkedList stack = (LinkedList) contexts.get(); |
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if (stack != null) |
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{ |
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stack.removeFirst(); |
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if (stack.isEmpty()) |
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contexts.set(null); |
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} |
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} |
} |
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/** |
/** |
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Boolean inCall = (Boolean) inGetContext.get(); |
Boolean inCall = (Boolean) inGetContext.get(); |
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if (inCall != null && inCall.booleanValue()) |
if (inCall != null && inCall.booleanValue()) |
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{ |
{ |
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if (DEBUG) debug ("already in getContext"); |
if (DEBUG) |
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debug("already in getContext"); |
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return DEFAULT_CONTEXT; |
return DEFAULT_CONTEXT; |
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} |
} |
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inGetContext.set(Boolean.TRUE); |
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Object[][] stack = getStack(); |
Object[][] stack = getStack(); |
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Class[] classes = (Class[]) stack[0]; |
Class[] classes = (Class[]) stack[0]; |
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String[] methods = (String[]) stack[1]; |
String[] methods = (String[]) stack[1]; |
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inGetContext.set (Boolean.TRUE); |
if (DEBUG) |
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debug(">>> got trace of length " + classes.length); |
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if (DEBUG) debug (">>> got trace of length " + classes.length); |
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HashSet domains = new HashSet(); |
HashSet domains = new HashSet(); |
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HashSet seenDomains = new HashSet(); |
HashSet seenDomains = new HashSet(); |
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AccessControlContext context = null; |
AccessControlContext context = null; |
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int privileged = 0; |
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// We walk down the stack, adding each ProtectionDomain for each |
// We walk down the stack, adding each ProtectionDomain for each |
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// class in the call stack. If we reach a call to doPrivileged, |
// class in the call stack. If we reach a call to doPrivileged, |
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// we don't add any more stack frames. We skip the first three stack |
// we don't add any more stack frames. We skip the first three stack |
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// frames, since they comprise the calls to getStack, getContext, |
// frames, since they comprise the calls to getStack, getContext, |
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// and AccessController.getContext. |
// and AccessController.getContext. |
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for (int i = 3; i < classes.length; i++) |
for (int i = 3; i < classes.length && privileged < 2; i++) |
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{ |
{ |
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Class clazz = classes[i]; |
Class clazz = classes[i]; |
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String method = methods[i]; |
String method = methods[i]; |
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if (DEBUG) |
if (DEBUG) |
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{ |
{ |
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debug (">>> checking " + clazz + "." + method); |
debug(">>> checking " + clazz + "." + method); |
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debug (">>> loader = " + clazz.getClassLoader()); |
debug(">>> loader = " + clazz.getClassLoader()); |
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} |
} |
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// If the previous frame was a call to doPrivileged, then this is |
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// the last frame we look at. |
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if (privileged == 1) |
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privileged = 2; |
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if (clazz.equals (AccessController.class) |
if (clazz.equals (AccessController.class) |
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&& method.equals ("doPrivileged")) |
&& method.equals ("doPrivileged")) |
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{ |
{ |
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// If there was a call to doPrivileged with a supplied context, |
// If there was a call to doPrivileged with a supplied context, |
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// return that context. |
// return that context. |
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List pair = new ArrayList(2); |
LinkedList l = (LinkedList) contexts.get(); |
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pair.add (Thread.currentThread()); |
if (l != null) |
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pair.add (classes[i-1]); |
context = (AccessControlContext) l.getFirst(); |
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if (contexts.containsKey (pair)) |
privileged = 1; |
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context = (AccessControlContext) contexts.get (pair); |
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break; |
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} |
} |
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ProtectionDomain domain = clazz.getProtectionDomain(); |
ProtectionDomain domain = clazz.getProtectionDomain(); |
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if (domain == null) |
if (domain == null) |
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continue; |
continue; |
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if (seenDomains.contains (domain)) |
if (seenDomains.contains(domain)) |
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continue; |
continue; |
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seenDomains.add (domain); |
seenDomains.add(domain); |
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// Create a static snapshot of this domain, which may change over time |
// Create a static snapshot of this domain, which may change over time |
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// if the current policy changes. |
// if the current policy changes. |
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domains.add (new ProtectionDomain (domain.getCodeSource(), |
domains.add(new ProtectionDomain(domain.getCodeSource(), |
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domain.getPermissions())); |
domain.getPermissions())); |
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} |
} |
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if (DEBUG) debug ("created domains: " + domains); |
if (DEBUG) |
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debug("created domains: " + domains); |
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ProtectionDomain[] result = (ProtectionDomain[]) |
ProtectionDomain[] result = (ProtectionDomain[]) |
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domains.toArray (new ProtectionDomain[domains.size()]); |
domains.toArray(new ProtectionDomain[domains.size()]); |
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// Intersect the derived protection domain with the context supplied |
// Intersect the derived protection domain with the context supplied |
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// to doPrivileged. |
// to doPrivileged. |
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if (context != null) |
if (context != null) |
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context = new AccessControlContext (result, context, |
context = new AccessControlContext(result, context, |
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IntersectingDomainCombiner.SINGLETON); |
IntersectingDomainCombiner.SINGLETON); |
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// No context was supplied. Return the derived one. |
// No context was supplied. Return the derived one. |
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else |
else |
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context = new AccessControlContext (result); |
context = new AccessControlContext(result); |
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inGetContext.set (Boolean.FALSE); |
inGetContext.set(Boolean.FALSE); |
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return context; |
return context; |
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} |
} |
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