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Message-ID: <20240809122007.1220219-2-masahiroy@kernel.org>
Date: Fri, 9 Aug 2024 21:19:01 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Paul Moore <paul@...l-moore.com>,
linux-security-module@...r.kernel.org
Cc: linux-kbuild@...r.kernel.org,
linux-kernel@...r.kernel.org,
Daniel Gomez <da.gomez@...sung.com>,
Masahiro Yamada <masahiroy@...nel.org>,
Ondrej Mosnacek <omosnace@...hat.com>,
Stephen Smalley <stephen.smalley.work@...il.com>,
selinux@...r.kernel.org
Subject: [PATCH 1/2] selinux: do not include <linux/*.h> headers from host programs
Commit bfc5e3a6af39 ("selinux: use the kernel headers when building
scripts/selinux") is not the right thing to do.
It is clear from the warning in include/uapi/linux/types.h:
#ifndef __EXPORTED_HEADERS__
#warning "Attempt to use kernel headers from user space, see https://kernelnewbies.org/KernelHeaders"
#endif /* __EXPORTED_HEADERS__ */
If you are inclined to define __EXPORTED_HEADERS__, you are likely doing
wrong.
Adding the comment:
/* NOTE: we really do want to use the kernel headers here */
does not justify the hack in any way.
Currently, <linux/*.h> headers are included for the following purposes:
- <linux/capability.h> is included to check CAP_LAST_CAP
- <linux/socket.h> in included to check PF_MAX
We can skip these checks when building host programs, as they will
be eventually tested when building the kernel space.
I got rid of <linux/stddef.h> from initial_sid_to_string.h because
it is likely that NULL is already defined. If you insist on making
it self-contained, you can add the following:
#ifdef __KERNEL__
#include <linux/stddef.h>
#else
#include <stddef.h>
#endif
scripts/selinux/mdp/mdp.c still includes <linux/kconfig.h>, which is
also discouraged and should be fixed by a follow-up refactoring.
Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---
scripts/selinux/genheaders/Makefile | 4 +---
scripts/selinux/genheaders/genheaders.c | 3 ---
scripts/selinux/mdp/Makefile | 2 +-
scripts/selinux/mdp/mdp.c | 4 ----
security/selinux/include/classmap.h | 19 ++++++++++++-------
.../selinux/include/initial_sid_to_string.h | 2 --
6 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/scripts/selinux/genheaders/Makefile b/scripts/selinux/genheaders/Makefile
index 1faf7f07e8db..866f60e78882 100644
--- a/scripts/selinux/genheaders/Makefile
+++ b/scripts/selinux/genheaders/Makefile
@@ -1,5 +1,3 @@
# SPDX-License-Identifier: GPL-2.0
hostprogs-always-y += genheaders
-HOST_EXTRACFLAGS += \
- -I$(srctree)/include/uapi -I$(srctree)/include \
- -I$(srctree)/security/selinux/include
+HOST_EXTRACFLAGS += -I$(srctree)/security/selinux/include
diff --git a/scripts/selinux/genheaders/genheaders.c b/scripts/selinux/genheaders/genheaders.c
index 15520806889e..3834d7eb0af6 100644
--- a/scripts/selinux/genheaders/genheaders.c
+++ b/scripts/selinux/genheaders/genheaders.c
@@ -1,8 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
-/* NOTE: we really do want to use the kernel headers here */
-#define __EXPORTED_HEADERS__
-
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
diff --git a/scripts/selinux/mdp/Makefile b/scripts/selinux/mdp/Makefile
index d61058ddd15c..673782e3212f 100644
--- a/scripts/selinux/mdp/Makefile
+++ b/scripts/selinux/mdp/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
hostprogs-always-y += mdp
HOST_EXTRACFLAGS += \
- -I$(srctree)/include/uapi -I$(srctree)/include \
+ -I$(srctree)/include \
-I$(srctree)/security/selinux/include -I$(objtree)/include
clean-files := policy.* file_contexts
diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
index 1415604c3d24..52365921c043 100644
--- a/scripts/selinux/mdp/mdp.c
+++ b/scripts/selinux/mdp/mdp.c
@@ -11,10 +11,6 @@
* Authors: Serge E. Hallyn <serue@...ibm.com>
*/
-
-/* NOTE: we really do want to use the kernel headers here */
-#define __EXPORTED_HEADERS__
-
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 7229c9bf6c27..518209e1beb0 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -1,8 +1,5 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/capability.h>
-#include <linux/socket.h>
-
#define COMMON_FILE_SOCK_PERMS \
"ioctl", "read", "write", "create", "getattr", "setattr", "lock", \
"relabelfrom", "relabelto", "append", "map"
@@ -36,10 +33,6 @@
"mac_override", "mac_admin", "syslog", "wake_alarm", "block_suspend", \
"audit_read", "perfmon", "bpf", "checkpoint_restore"
-#if CAP_LAST_CAP > CAP_CHECKPOINT_RESTORE
-#error New capability defined, please update COMMON_CAP2_PERMS.
-#endif
-
/*
* Note: The name for any socket class should be suffixed by "socket",
* and doesn't contain more than one substr of "socket".
@@ -181,6 +174,18 @@ const struct security_class_mapping secclass_map[] = {
{ NULL }
};
+#ifdef __KERNEL__ /* avoid this check when building host programs */
+
+#include <linux/capability.h>
+
+#if CAP_LAST_CAP > CAP_CHECKPOINT_RESTORE
+#error New capability defined, please update COMMON_CAP2_PERMS.
+#endif
+
+#include <linux/socket.h>
+
#if PF_MAX > 46
#error New address family defined, please update secclass_map.
#endif
+
+#endif /* __KERNEL__ */
diff --git a/security/selinux/include/initial_sid_to_string.h b/security/selinux/include/initial_sid_to_string.h
index 99b353b2abb4..f683a78b21fd 100644
--- a/security/selinux/include/initial_sid_to_string.h
+++ b/security/selinux/include/initial_sid_to_string.h
@@ -1,7 +1,5 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/stddef.h>
-
static const char *const initial_sid_to_string[] = {
NULL, /* zero placeholder, not used */
"kernel", /* kernel / SECINITSID_KERNEL */
--
2.43.0
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