powerpc/powernv: Restrict OPAL symbol map to only be readable by root

commit e7de4f7b64c23e503a8c42af98d56f2a7462bd6d upstream.

Currently the OPAL symbol map is globally readable, which seems bad as
it contains physical addresses.

Restrict it to root.

Fixes: c8742f85 ("powerpc/powernv: Expose OPAL firmware symbol map")
Cc: stable@vger.kernel.org # v3.19+
Suggested-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190503075253.22798-1-ajd@linux.ibm.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/platforms/powernv/opal.c

@@ -680,7 +680,10 @@ static ssize_t symbol_map_read(struct file *fp, struct kobject *kobj,
 				       bin_attr->size);
 }
 
-static BIN_ATTR_RO(symbol_map, 0);
+static struct bin_attribute symbol_map_attr = {
+	.attr = {.name = "symbol_map", .mode = 0400},
+	.read = symbol_map_read
+};
 
 static void opal_export_symmap(void)
 {
@@ -697,10 +700,10 @@ static void opal_export_symmap(void)
 		return;
 
 	/* Setup attributes */
-	bin_attr_symbol_map.private = __va(be64_to_cpu(syms[0]));
-	bin_attr_symbol_map.size = be64_to_cpu(syms[1]);
+	symbol_map_attr.private = __va(be64_to_cpu(syms[0]));
+	symbol_map_attr.size = be64_to_cpu(syms[1]);
 
-	rc = sysfs_create_bin_file(opal_kobj, &bin_attr_symbol_map);
+	rc = sysfs_create_bin_file(opal_kobj, &symbol_map_attr);
 	if (rc)
 		pr_warn("Error %d creating OPAL symbols file\n", rc);
 }