Page History

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This noncompliant example grants AllPermission to the klib library.

// Grant the klib library AllPermission  
grant codebase "file:${klib.home}/j2se/home/klib.jar" { 
  permission java.security.AllPermission; 
}; 

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This compliant solution shows a policy file that can be used to enforce fine-grained permissions.

grant codeBase 
    "file:${klib.home}/j2se/home/klib.jar", signedBy "Admin" {
  permission java.io.FilePermission "/tmp/*", "read";
  permission java.io.SocketPermission "*", "connect";
};

To check whether the caller has the requisite permissions, standard Java APIs use code such as the following:

// Security manager check
FilePermission perm =
    new java.io.FilePermission("/tmp/JavaFile", "read");
AccessController.checkPermission(perm);
// ...

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This noncompliant code example shows an overridden getPermissions() method, defined in a custom class loader. It grants java.lang.ReflectPermission with target suppressAccessChecks to any class that it loads.

protected PermissionCollection getPermissions(CodeSource cs) {
  PermissionCollection pc = super.getPermissions(cs);
  pc.add(new ReflectPermission("suppressAccessChecks"));   // permission to create a class loader
  // other permissions
  return pc;
}

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This compliant solution does not grant java.lang.ReflectPermission with target suppressAccessChecks to any class that it loads.

protected PermissionCollection getPermissions(CodeSource cs) {
  PermissionCollection pc = super.getPermissions(cs);
  // other permissions
  return pc;
}

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ENV03-EX0: It may be necessary to grant AllPermission to trusted library code so that callbacks work as expected. For example, it is common practice, and acceptable, to grant AllPermission to the optional Java packages (extension libraries):

// Standard extensions extend the core platform and are granted all permissions by default
grant codeBase "file:${{java.ext.dirs}}/*" {
  permission java.security.AllPermission;
};

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Automated Detection

Static detection of potential uses of dangerous permissions is a trivial search. Automated determination of the correctness of such uses is not feasible.

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Android Implementation Details

The java.security package exists on Android for compatibility purposes only and it should not be used. Android uses another permission mechanism for security purposes.

Bibliography

      15. Runtime Environment (ENV)