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  1. PO
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    <p>Yes ! That's it.</p> <p>I have thought about that yesterday afternoon, and I went on the same solution. I'll post here my code for those who would be curious of that. 1) The NativeRMISecurityManager 2) The C code (you have to generate the .h with javah</p> <p>(nb: I won't traduce it in english as there are loads of french comments)</p> <pre><code>package rmi; import java.rmi.RMISecurityManager; /** * &lt;p&gt; Ce SecurityManager, qui herite de RMISecurityManager, * implemente une verification supplementaire des droits * d'acces aux fichiers. * A la creation du SecurityManager et lors de la creation * de nouveaux threads, on renseigne ThreadLocal du nom du * _user_ du thread. * &lt;p&gt;Ainsi, lors des checkRead() et checkWrite() * notre SecurityManager appelle une methode native (JNI) * qui va verifier directement si le user a les droits * d'acces a la ressource. * &lt;p&gt;&lt;b&gt;Warning : NE PAS OUBLIER DE FAIRE APPEL A * setCurrentUser() DANS CHAQUE THREAD CREE.&lt;/b&gt; * &lt;p&gt; &lt;b&gt;Remarque :&lt;/b&gt; Pour les informations sur la compilation * et l'execution de la lib ecrite en C, cf. le fichier README. * @author a_po */ public class NativeRMISecurityManager extends RMISecurityManager { private boolean unix; protected ThreadLocal user = new ThreadLocal(); /** * Constructeur par defaut. * &lt;p&gt;&lt;b&gt;ATTENTION :&lt;/b&gt; Bien faire appel a la methode setCurrentUser(String) ! * Sinon le SecurityManager se comportera comme un RMISecurityManager classique. * @see public void setCurrentUser(String userName) */ public NativeRMISecurityManager() { super(); String OS = System.getProperty("os.name").toLowerCase(); unix = (OS.compareTo("windows") != 0); /* Si le systeme * n'EST PAS windows, * alors c'est UNIX... * * Pas tres rigoureux, * mais sinon il faut tester * Systeme V, Linux, *BSD, * Sun OS, ... */ /* * User du ThreadLocal : Chaque thread est considere comme ayant des * droits d'acces au systeme potentiellement differents. */ this.user.set(user); if (!unix) { System.out.println("Systeme : "+OS); } } /** * Verification en lecture. * &lt;p&gt; * Dans le cas ou l'on est sur une plateforme POSIX, * on souhaite verifier que le _user_ du Thread a le droit * de lecture sur le fichier. * &lt;p&gt; * De plus, dans le cas ou user est null, cela signifie * OBLIGATOIREMENT que le thread a ete cree "automatiquement" * et que le thread courant n'est pas un thread de "tache a executer". * &lt;p&gt; * En effet, le user est recupere dans le ThreadLocal * et on force l'initialisation de cette variable a l'instanciation * du SecurityManager (en mettant le constructeur par defaut prive) ou * en faisant appel a setCurrentUser(String) * @see void rmi.NativeRMISecurityManager.setCurrentUser(String user) */ public void checkRead(String file) { super.checkRead(file); String str_user = (String)this.user.get(); if (unix &amp;&amp; str_user != null) { if (file == null) { throw new SecurityException("file = NULL !!!"); } int ret = c_checkRead(file, str_user); if (ret != 0) { throw new SecurityException("Erreur d'acces au fichier : " + file); } } } /** * Verification d'acces en ecriture sur un fichier. * @see void rmi.NativeRMISecurityManager.checkRead(String file) */ public void checkWrite(String file) { super.checkWrite(file); String str_user = (String)this.user.get(); if (unix &amp;&amp; str_user != null) { if (file == null) { throw new SecurityException("file = NULL !!!"); } int ret = c_checkWrite(file, str_user); if (ret != 0) { throw new SecurityException("Erreur d'acces au fichier : " + file); } } } /** * Configure le thread courant pour que le user soit pris en compte * dans les verifications d'acces aux fichiers. * @param user */ public void setCurrentUser(String userName) { this.user = new ThreadLocal(); this.user.set(userName); } public String getCurrentUser() { if (user!=null){ return (String)user.get(); } else return null; } /** * Methode native a implementer en C. * @param file * @param user * @return 0 si ok &lt;p&gt; -1 sinon */ public native int c_checkRead(String file, String user); /** * Idem que pour c_checkRead * @param file * @param user * @return * @see int rmi.NativeRMISecurityManager.c_checkRead(String file, String user) */ public native int c_checkWrite(String file, String user); /** * Chargement de la bibliotheque JNI. */ static { System.loadLibrary("rmi_NativeRMISecurityManager"); } } </code></pre> <p>And the C library:</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;jni.h&gt; #include &lt;sys/stat.h&gt; #include &lt;sys/types.h&gt; #include &lt;unistd.h&gt; #include &lt;pwd.h&gt; #include &lt;stdlib.h&gt; #include &lt;grp.h&gt; #include &lt;string.h&gt; #include "rmi_NativeRMISecurityManager.h" /* Droits en lecture / ecriture / execution */ #define R_RIGHT 4 #define X_RIGHT 1 #define W_RIGHT 2 JNIEXPORT jint JNICALL Java_rmi_NativeRMISecurityManager_c_1checkRead (JNIEnv *env, jobject obj, jstring file, jstring user) { int ret = check_permission(env, obj, file, user); /** * La permission d'acces a un fichier vaut ceci : * 1 pour l'execution * 2 pour l'ecriture * 4 pour la lecture. * Donc : * * Droit en lecture : 4, 5, 6, 7 * * Droit en ecriture : 2, 3, 6, 7 * * Droit en execution : 1, 3, 5, 7. */ if (ret == R_RIGHT || ret == R_RIGHT + W_RIGHT || ret == R_RIGHT + X_RIGHT || ret == R_RIGHT + W_RIGHT + X_RIGHT) { return 0; } else return -1; } JNIEXPORT jint JNICALL Java_rmi_NativeRMISecurityManager_c_1checkWrite (JNIEnv *env, jobject obj, jstring file, jstring user) { int ret = check_permission(env, obj, file, user); /** * La permission d'acces a un fichier vaut ceci : * 1 pour l'execution * 2 pour l'ecriture * 4 pour la lecture. * Donc : * * Droit en lecture : 4, 5, 6, 7 * * Droit en ecriture : 2, 3, 6, 7 * * Droit en execution : 1, 3, 5, 7. */ if (ret == W_RIGHT || ret == W_RIGHT + R_RIGHT || ret == W_RIGHT + X_RIGHT || ret == W_RIGHT + R_RIGHT + X_RIGHT) { return 0; } else return -1; } int check_permission(JNIEnv *env, jobject obj, jstring file, jstring user) { struct stat pstat; const char* pzcfile = (*env)-&gt;GetStringUTFChars(env, file, 0); const char* pzcuser = (*env)-&gt;GetStringUTFChars(env, user, 0); struct passwd* puserInfo; int bisOwner = 0; int bisGroup = 0; struct group* pgroupInfo; int i; int droits = 0; /* recuperer les informations relatives au fichier */ if(lstat(pzcfile, &amp;pstat)&lt;0) { fprintf(stderr,"* Le fichier %s n'exite pas.\n", pzcfile); (*env)-&gt;ReleaseStringUTFChars(env, file, pzcfile); (*env)-&gt;ReleaseStringUTFChars(env, user, pzcuser); return -1; } /* recuperer l'identifiant du user */ puserInfo = getpwnam(pzcuser); if(puserInfo == NULL) { fprintf(stderr,"* L'utilisateur %s n'est pas connu du systeme.\n", pzcuser); (*env)-&gt;ReleaseStringUTFChars(env, file, pzcfile); (*env)-&gt;ReleaseStringUTFChars(env, user, pzcuser); return -2; } /* regarder si le user est proprietaire du fichier */ if(puserInfo-&gt;pw_uid == pstat.st_uid) { bisOwner = 1; } /* si le user n'est pas proprietaire, verifier s'il est membre du groupe */ if(!bisOwner) { /* recuperer les informations relatives au groupe */ pgroupInfo = getgrgid(pstat.st_gid); /* parcourir la liste des membres du groupe a la recherche du user */ for(i=0;;i++) { if(pgroupInfo-&gt;gr_mem[i] == NULL) { break; } if(strcmp(pgroupInfo-&gt;gr_mem[i],pzcuser) == 0) { bisGroup = 1; break; } } } /* recuperer les droits correspondants au user */ if(bisOwner) { droits = (pstat.st_mode &amp; S_IRWXU) &gt;&gt; 6; } else if(bisGroup) { droits = (pstat.st_mode &amp; S_IRWXG) &gt;&gt; 3; } else { droits = pstat.st_mode &amp; S_IRWXO; } /* liberer les espaces memoire alloues */ (*env)-&gt;ReleaseStringUTFChars(env, file, pzcfile); (*env)-&gt;ReleaseStringUTFChars(env, user, pzcuser); return droits; } </code></pre> <p>Thank you very much Greg Case. This comfort me because we have found the same solution. :)</p>
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    1. POHow to automatically copy data to new RMI threads?
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    1. USCreasixtine
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    1. COIs this working for you? It looks like only one Thread has a user at a time - the user for other threads is dereferenced each time setCurrentUser is called. This would make all other threads automatically priviledged, even if they previously had a user.
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      1. USGreg Case
    2. COApparently not, I have done this test : 1) Thread 1 : Set user = "someone" (thread.sleep(...)) 2) Thread 2 : Set user = "root" (sleep) 3) Thread 1 : Open a file and display the thread's user 4) Thread 2 : Similar thing And it happens what we want... Have you tried something like that ?
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    3. COHmm. The only thing I can think of is that the reference is non-volatile, so perhaps it's not being refreshed for all threads when the reference changes. However, if it works for you then my theorizing is irrelevant. Good luck!
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      1. USGreg Case
 

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