kernel/module: Hide vermagic header file from general use

VERMAGIC* definitions are not supposed to be used by the drivers, see this [1] bug report, so introduce special define to guard inclusion of this header file and define it in kernel/modules.h and in internal script that generates *.mod.c files. In-tree module build: ➜ kernel git:(vermagic) ✗ make clean ➜ kernel git:(vermagic) ✗ make M=drivers/infiniband/hw/mlx5 ➜ kernel git:(vermagic) ✗ modinfo drivers/infiniband/hw/mlx5/mlx5_ib.ko filename: /images/leonro/src/kernel/drivers/infiniband/hw/mlx5/mlx5_ib.ko <...> vermagic: 5.6.0+ SMP mod_unload modversions Out-of-tree module build: ➜ mlx5 make -C /images/leonro/src/kernel clean M=/tmp/mlx5 ➜ mlx5 make -C /images/leonro/src/kernel M=/tmp/mlx5 ➜ mlx5 modinfo /tmp/mlx5/mlx5_ib.ko filename: /tmp/mlx5/mlx5_ib.ko <...> vermagic: 5.6.0+ SMP mod_unload modversions [1] https://lore.kernel.org/lkml/[email protected] Reported-by: Borislav Petkov <[email protected]> Acked-by: Borislav Petkov <[email protected]> Acked-by: Jessica Yu <[email protected]> Co-developed-by: Masahiro Yamada <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Leon Romanovsky <[email protected]> Signed-off-by: David S. Miller <[email protected]>
majek · Apr 21, 2020 · 51161bf · 51161bf
1 parent b4f3721
commit 51161bf
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diff --git a/include/linux/vermagic.h b/include/linux/vermagic.h
@@ -1,4 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef INCLUDE_VERMAGIC
+#error "This header can be included from kernel/module.c or *.mod.c only"
+#endif
+
 #include <generated/utsrelease.h>
 
 /* Simply sanity version stamp for modules. */

diff --git a/kernel/module.c b/kernel/module.c
@@ -4,6 +4,9 @@
    Copyright (C) 2001 Rusty Russell, 2002, 2010 Rusty Russell IBM.
 
 */
+
+#define INCLUDE_VERMAGIC
+
 #include <linux/export.h>
 #include <linux/extable.h>
 #include <linux/moduleloader.h>

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
@@ -2251,6 +2251,7 @@ static void add_header(struct buffer *b, struct module *mod)
 	 * Include build-salt.h after module.h in order to
 	 * inherit the definitions.
 	 */
+	buf_printf(b, "#define INCLUDE_VERMAGIC\n");
 	buf_printf(b, "#include <linux/build-salt.h>\n");
 	buf_printf(b, "#include <linux/vermagic.h>\n");
 	buf_printf(b, "#include <linux/compiler.h>\n");