diff mbox series

[v5,2/5] security: Count the LSMs enabled at compile time

Message ID 20230928202410.3765062-3-kpsingh@kernel.org (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Reduce overhead of LSMs with static calls | expand

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Commit Message

KP Singh Sept. 28, 2023, 8:24 p.m. UTC 
These macros are a clever trick to determine a count of the number of
LSMs that are enabled in the config to ascertain the maximum number of
static calls that need to be configured per LSM hook.

Without this one would need to generate static calls for the total
number of LSMs in the kernel (even if they are not compiled) times the
number of LSM hooks which ends up being quite wasteful.

Suggested-by: Kui-Feng Lee <sinquersw@gmail.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
 include/linux/lsm_count.h | 114 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 include/linux/lsm_count.h

Comments

Kees Cook Sept. 29, 2023, 12:37 a.m. UTC | #1 
On Thu, Sep 28, 2023 at 10:24:07PM +0200, KP Singh wrote:
> These macros are a clever trick to determine a count of the number of
> LSMs that are enabled in the config to ascertain the maximum number of
> static calls that need to be configured per LSM hook.
> 
> Without this one would need to generate static calls for the total
> number of LSMs in the kernel (even if they are not compiled) times the
> number of LSM hooks which ends up being quite wasteful.
> 
> Suggested-by: Kui-Feng Lee <sinquersw@gmail.com>
> Suggested-by: Andrii Nakryiko <andrii@kernel.org>
> Acked-by: Song Liu <song@kernel.org>
> Signed-off-by: KP Singh <kpsingh@kernel.org>

Thanks for doing the refactor with the existing macro!

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

diff --git a/include/linux/lsm_count.h b/include/linux/lsm_count.h
new file mode 100644
index 000000000000..dbb3c8573959
--- /dev/null
+++ b/include/linux/lsm_count.h
@@ -0,0 +1,114 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Copyright (C) 2023 Google LLC.
+ */
+
+#ifndef __LINUX_LSM_COUNT_H
+#define __LINUX_LSM_COUNT_H
+
+#include <linux/args.h>
+
+#ifdef CONFIG_SECURITY
+
+/*
+ * Macros to count the number of LSMs enabled in the kernel at compile time.
+ */
+
+/*
+ * Capabilities is enabled when CONFIG_SECURITY is enabled.
+ */
+#if IS_ENABLED(CONFIG_SECURITY)
+#define CAPABILITIES_ENABLED 1,
+#else
+#define CAPABILITIES_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_SELINUX)
+#define SELINUX_ENABLED 1,
+#else
+#define SELINUX_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_SMACK)
+#define SMACK_ENABLED 1,
+#else
+#define SMACK_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_APPARMOR)
+#define APPARMOR_ENABLED 1,
+#else
+#define APPARMOR_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_TOMOYO)
+#define TOMOYO_ENABLED 1,
+#else
+#define TOMOYO_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_YAMA)
+#define YAMA_ENABLED 1,
+#else
+#define YAMA_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_LOADPIN)
+#define LOADPIN_ENABLED 1,
+#else
+#define LOADPIN_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_LOCKDOWN_LSM)
+#define LOCKDOWN_ENABLED 1,
+#else
+#define LOCKDOWN_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_SAFESETID)
+#define SAFESETID_ENABLED 1,
+#else
+#define SAFESETID_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_BPF_LSM)
+#define BPF_LSM_ENABLED 1,
+#else
+#define BPF_LSM_ENABLED
+#endif
+
+#if IS_ENABLED(CONFIG_SECURITY_LANDLOCK)
+#define LANDLOCK_ENABLED 1,
+#else
+#define LANDLOCK_ENABLED
+#endif
+
+/*
+ *  There is a trailing comma that we need to be accounted for. This is done by
+ *  using a skipped argument in __COUNT_LSMS
+ */
+#define __COUNT_LSMS(skipped_arg, args...) COUNT_ARGS(args...)
+#define COUNT_LSMS(args...) __COUNT_LSMS(args)
+
+#define MAX_LSM_COUNT			\
+	COUNT_LSMS(			\
+		CAPABILITIES_ENABLED	\
+		SELINUX_ENABLED		\
+		SMACK_ENABLED		\
+		APPARMOR_ENABLED	\
+		TOMOYO_ENABLED		\
+		YAMA_ENABLED		\
+		LOADPIN_ENABLED		\
+		LOCKDOWN_ENABLED	\
+		SAFESETID_ENABLED	\
+		BPF_LSM_ENABLED		\
+		LANDLOCK_ENABLED)
+
+#else
+
+#define MAX_LSM_COUNT 0
+
+#endif /* CONFIG_SECURITY */
+
+#endif  /* __LINUX_LSM_COUNT_H */