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13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
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24  */
25 
26 package sun.nio.fs;
27 
28 import static sun.nio.fs.WindowsNativeDispatcher.*;
29 import static sun.nio.fs.WindowsConstants.*;
30 
31 /**
32  * Security related utility methods.
33  */
34 
35 class WindowsSecurity {
WindowsSecurity()36     private WindowsSecurity() { }
37 
38     // opens process token for given access
openProcessToken(int access)39     private static long openProcessToken(int access) {
40         try {
41             return OpenProcessToken(GetCurrentProcess(), access);
42         } catch (WindowsException x) {
43             return 0L;
44         }
45     }
46 
47     /**
48      * Returns the access token for this process with TOKEN_DUPLICATE access
49      */
50     static final long processTokenWithDuplicateAccess =
51         openProcessToken(TOKEN_DUPLICATE);
52 
53     /**
54      * Returns the access token for this process with TOKEN_QUERY access
55      */
56     static final long processTokenWithQueryAccess =
57         openProcessToken(TOKEN_QUERY);
58 
59     /**
60      * Returned by enablePrivilege when code may require a given privilege.
61      * The drop method should be invoked after the operation completes so as
62      * to revert the privilege.
63      */
64     static interface Privilege {
drop()65         void drop();
66     }
67 
68     /**
69      * Attempts to enable the given privilege for this method.
70      */
enablePrivilege(String priv)71     static Privilege enablePrivilege(String priv) {
72         final long pLuid;
73         try {
74             pLuid = LookupPrivilegeValue(priv);
75         } catch (WindowsException x) {
76             // indicates bug in caller
77             throw new AssertionError(x);
78         }
79 
80         long hToken = 0L;
81         boolean impersontating = false;
82         boolean elevated = false;
83         try {
84             hToken = OpenThreadToken(GetCurrentThread(),
85                                      TOKEN_ADJUST_PRIVILEGES, false);
86             if (hToken == 0L && processTokenWithDuplicateAccess != 0L) {
87                 hToken = DuplicateTokenEx(processTokenWithDuplicateAccess,
88                     (TOKEN_ADJUST_PRIVILEGES|TOKEN_IMPERSONATE));
89                 SetThreadToken(0L, hToken);
90                 impersontating = true;
91             }
92 
93             if (hToken != 0L) {
94                 AdjustTokenPrivileges(hToken, pLuid, SE_PRIVILEGE_ENABLED);
95                 elevated = true;
96             }
97         } catch (WindowsException x) {
98             // nothing to do, privilege not enabled
99         }
100 
101         final long token = hToken;
102         final boolean stopImpersontating = impersontating;
103         final boolean needToRevert = elevated;
104 
105         return () -> {
106             try {
107                 if (token != 0L) {
108                     try {
109                         if (stopImpersontating)
110                             SetThreadToken(0L, 0L);
111                         else if (needToRevert)
112                             AdjustTokenPrivileges(token, pLuid, 0);
113                     } catch (WindowsException x) {
114                         // should not happen
115                         throw new AssertionError(x);
116                     } finally {
117                         CloseHandle(token);
118                     }
119                 }
120             } finally {
121                 LocalFree(pLuid);
122             }
123         };
124     }
125 
126     /**
127      * Check the access right against the securityInfo in the current thread.
128      */
129     static boolean checkAccessMask(long securityInfo, int accessMask,
130         int genericRead, int genericWrite, int genericExecute, int genericAll)
131         throws WindowsException
132     {
133         int privilegies = TOKEN_QUERY;
134         long hToken = OpenThreadToken(GetCurrentThread(), privilegies, false);
135         if (hToken == 0L && processTokenWithDuplicateAccess != 0L)
136             hToken = DuplicateTokenEx(processTokenWithDuplicateAccess,
137                 privilegies);
138 
139         boolean hasRight = false;
140         if (hToken != 0L) {
141             try {
142                 hasRight = AccessCheck(hToken, securityInfo, accessMask,
143                     genericRead, genericWrite, genericExecute, genericAll);
144             } finally {
145                 CloseHandle(hToken);
146             }
147         }
148         return hasRight;
149     }
150 
151 }
152