Permit filesystem group to be root

changes/bug17562-allow-root-group-read

@@ -0,0 +1,6 @@
+  o Minor bug fixes:
+    - If any directory created by Tor is marked as group readable, the
+      filesystem group is allowed to be either the default GID or the root
+      user. Allowing root to read the DataDirectory prevents the need for
+      CAP_READ_SEARCH when using systemd's CapabilityBoundingSet, or
+      dac_read_search when using SELinux.

src/common/util.c

@@ -2143,7 +2143,7 @@ check_private_dir(const char *dirname, cpd_check_t check,
     return -1;
   }
   if ( (check & (CPD_GROUP_OK|CPD_GROUP_READ))
-       && (st.st_gid != running_gid) ) {
+       && (st.st_gid != running_gid) && (st.st_gid != 0)) {
     struct group *gr;
     char *process_groupname = NULL;
     gr = getgrgid(running_gid);