[PATCH bpf-next v1 02/13] bpf: lsm: Add a skeleton and config options

[KP Singh <kpsingh@chromium.org>]

From: KP Singh <kpsingh@google.com>

The LSM can be enabled by CONFIG_SECURITY_BPF.
Without CONFIG_SECURITY_BPF_ENFORCE, the LSM will run the
attached eBPF programs but not enforce MAC policy based
on the return value of the attached programs.

Signed-off-by: KP Singh <kpsingh@google.com>
---
 MAINTAINERS           |  7 +++++++
 security/Kconfig      | 11 ++++++-----
 security/Makefile     |  2 ++
 security/bpf/Kconfig  | 25 +++++++++++++++++++++++++
 security/bpf/Makefile |  5 +++++
 security/bpf/lsm.c    | 28 ++++++++++++++++++++++++++++
 6 files changed, 73 insertions(+), 5 deletions(-)
 create mode 100644 security/bpf/Kconfig
 create mode 100644 security/bpf/Makefile
 create mode 100644 security/bpf/lsm.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8f075b866aaf..3b82d8ff21fb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3175,6 +3175,13 @@ S:	Supported
 F:	arch/x86/net/
 X:	arch/x86/net/bpf_jit_comp32.c
 
+BPF SECURITY MODULE
+M:	KP Singh <kpsingh@chromium.org>
+L:	linux-security-module@vger.kernel.org
+L:	bpf@vger.kernel.org
+S:	Maintained
+F:	security/bpf/
+
 BROADCOM B44 10/100 ETHERNET DRIVER
 M:	Michael Chan <michael.chan@broadcom.com>
 L:	netdev@vger.kernel.org
diff --git a/security/Kconfig b/security/Kconfig
index 2a1a2d396228..6f1aab195e7d 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -236,6 +236,7 @@ source "security/tomoyo/Kconfig"
 source "security/apparmor/Kconfig"
 source "security/loadpin/Kconfig"
 source "security/yama/Kconfig"
+source "security/bpf/Kconfig"
 source "security/safesetid/Kconfig"
 source "security/lockdown/Kconfig"
 
@@ -277,11 +278,11 @@ endchoice
 
 config LSM
 	string "Ordered list of enabled LSMs"
-	default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK
-	default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR
-	default "lockdown,yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
-	default "lockdown,yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC
-	default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
+	default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
+	default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
+	default "lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
+	default "lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
+	default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
 	help
 	  A comma-separated list of LSMs, in initialization order.
 	  Any LSMs left off this list will be ignored. This can be
diff --git a/security/Makefile b/security/Makefile
index be1dd9d2cb2f..50e6821dd7b7 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -12,6 +12,7 @@ subdir-$(CONFIG_SECURITY_YAMA)		+= yama
 subdir-$(CONFIG_SECURITY_LOADPIN)	+= loadpin
 subdir-$(CONFIG_SECURITY_SAFESETID)    += safesetid
 subdir-$(CONFIG_SECURITY_LOCKDOWN_LSM)	+= lockdown
+subdir-$(CONFIG_SECURITY_BPF)		+= bpf
 
 # always enable default capabilities
 obj-y					+= commoncap.o
@@ -29,6 +30,7 @@ obj-$(CONFIG_SECURITY_YAMA)		+= yama/
 obj-$(CONFIG_SECURITY_LOADPIN)		+= loadpin/
 obj-$(CONFIG_SECURITY_SAFESETID)       += safesetid/
 obj-$(CONFIG_SECURITY_LOCKDOWN_LSM)	+= lockdown/
+obj-$(CONFIG_SECURITY_BPF)		+= bpf/
 obj-$(CONFIG_CGROUP_DEVICE)		+= device_cgroup.o
 
 # Object integrity file lists
diff --git a/security/bpf/Kconfig b/security/bpf/Kconfig
new file mode 100644
index 000000000000..1aaa1340e795
--- /dev/null
+++ b/security/bpf/Kconfig
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright 2019 Google LLC.
+
+config SECURITY_BPF
+	bool "BPF-based MAC and audit policy"
+	depends on SECURITY
+	depends on SECURITYFS
+	depends on BPF
+	depends on BPF_SYSCALL
+	help
+	  This enables instrumentation of the security hooks with
+	  eBPF programs. The LSM creates per-hook files in securityfs to which
+	  eBPF programs can be attached.
+
+	  If you are unsure how to answer this question, answer N.
+
+config SECURITY_BPF_ENFORCE
+	bool "Deny operations based on the evaluation of the attached programs"
+	depends on SECURITY_BPF
+	help
+	  eBPF programs attached to hooks can be used for both auditing and
+	  enforcement. Enabling enforcement implies that the evaluation result
+	  from the attached eBPF programs will allow or deny the operation
+	  guarded by the security hook.
diff --git a/security/bpf/Makefile b/security/bpf/Makefile
new file mode 100644
index 000000000000..26a0ab6f99b7
--- /dev/null
+++ b/security/bpf/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright 2019 Google LLC.
+
+obj-$(CONFIG_SECURITY_BPF) := lsm.o
diff --git a/security/bpf/lsm.c b/security/bpf/lsm.c
new file mode 100644
index 000000000000..fe5c65bbdd45
--- /dev/null
+++ b/security/bpf/lsm.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2019 Google LLC.
+ */
+
+#include <linux/lsm_hooks.h>
+
+static int process_execution(struct linux_binprm *bprm)
+{
+	return 0;
+}
+
+static struct security_hook_list lsm_hooks[] __lsm_ro_after_init = {
+	LSM_HOOK_INIT(bprm_check_security, process_execution),
+};
+
+static int __init lsm_init(void)
+{
+	security_add_hooks(lsm_hooks, ARRAY_SIZE(lsm_hooks), "bpf");
+	pr_info("eBPF and LSM are friends now.\n");
+	return 0;
+}
+
+DEFINE_LSM(bpf) = {
+	.name = "bpf",
+	.init = lsm_init,
+};
-- 
2.20.1