Changeset 66842 in vbox for trunk/src/VBox

Timestamp:

May 8, 2017 9:03:57 PM (8 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

115296

Message:

Support/Hardening: Use realpath() to get absolute paths upon encountering the first symlinks

File:

• trunk/src/VBox/HostDrivers/Support/SUPR3HardenedVerify.cpp (modified) (6 diffs)

trunk/src/VBox/HostDrivers/Support/SUPR3HardenedVerify.cpp

@@ -86 +86 @@
 /** The max path length acceptable for a trusted path. */
 #define SUPR3HARDENED_MAX_PATH      260U
+
+/** Enable to resolve symlinks using realpath() instead of cooking our own stuff. */
+#define SUP_HARDENED_VERIFY_FOLLOW_SYMLINKS_USE_REALPATH 1
 
 #ifdef RT_OS_SOLARIS
@@ -1092 +1095 @@
 
 
-#if defined(RT_OS_DARWIN) || defined(RT_OS_LINUX)
+#ifndef SUP_HARDENED_VERIFY_FOLLOW_SYMLINKS_USE_REALPATH
+# if defined(RT_OS_DARWIN) || defined(RT_OS_LINUX)
 /**
  * Copies the error message to the error buffer and returns @a rc.
@@ -1105 +1109 @@
     return supR3HardenedSetErrorN(rc, pErrInfo, 1, pszMsg);
 }
+# endif
 #endif
 
@@ -1894 +1899 @@
      * Verify each component from the root up.
      */
+#ifndef SUP_HARDENED_VERIFY_FOLLOW_SYMLINKS_USE_REALPATH
     uint32_t                iLoops = 0;
+#endif
     SUPR3HARDENEDFSOBJSTATE FsObjState;
     uint32_t                iComponent = 0;
@@ -1916 +1923 @@
                 && S_ISLNK(FsObjState.Stat.st_mode))
             {
+#if SUP_HARDENED_VERIFY_FOLLOW_SYMLINKS_USE_REALPATH /* Another approach using realpath() and verifying the result when encountering a symlink. */
+                char *pszFilenameResolved = realpath(pszFilename, NULL);
+                if (pszFilenameResolved)
+                {
+                    rc = supR3HardenedVerifyFile(pszFilenameResolved, hNativeFile, fMaybe3rdParty, pErrInfo);
+                    free(pszFilenameResolved);
+                    return rc;
+                }
+                else
+                {
+                    int iErr = errno;
+                    supR3HardenedError(VERR_ACCESS_DENIED, false /*fFatal*/,
+                                       "supR3HardenedVerifyFileFollowSymlinks: Failed to resolve the real path '%s': %s (%d)\n",
+                                       pszFilename, strerror(iErr), iErr);
+                    return supR3HardenedSetError4(VERR_ACCESS_DENIED, pErrInfo,
+                                                  "realpath failed for '", pszFilename, "': ", strerror(iErr));
+                }
+#else
                 /* Don't loop forever. */
                 iLoops++;
@@ -1990 +2015 @@
                     return supR3HardenedSetError3(VERR_TOO_MANY_SYMLINKS, pErrInfo,
                                                   "Too many symbolic links: '", pszFilename, "'");
+#endif
             }
         }