[PATCH bpf-next v2 03/10] bpf: lsm: Introduce types for eBPF based LSM

[KP Singh]

From: KP Singh <kpsingh at google.com>

A new eBPF program type BPF_PROG_TYPE_LSM with an
expected attach type of BPF_LSM_MAC. Attachment to LSM hooks is not
implemented in this patch.

On defining the types for the program, the macros expect that
<prog_name>_prog_ops and <prog_name>_verifier_ops exist. This is
implicitly required by the macro:

  BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm, ...)

Signed-off-by: KP Singh <kpsingh at google.com>
---
 include/linux/bpf_types.h      |  4 ++++
 include/uapi/linux/bpf.h       |  2 ++
 kernel/bpf/syscall.c           |  6 ++++++
 security/bpf/Makefile          |  2 +-
 security/bpf/ops.c             | 28 ++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  2 ++
 tools/lib/bpf/libbpf_probes.c  |  1 +
 7 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 security/bpf/ops.c

diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 9f326e6ef885..2f5b054500d7 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -68,6 +68,10 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport,
 #if defined(CONFIG_BPF_JIT)
 BPF_PROG_TYPE(BPF_PROG_TYPE_STRUCT_OPS, bpf_struct_ops,
 	      void *, void *)
+#ifdef CONFIG_SECURITY_BPF
+BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm,
+	       void *, void *)
+#endif /* CONFIG_SECURITY_BPF */
 #endif
 
 BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 52966e758fe5..b6a725a8a21d 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -176,6 +176,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_CGROUP_SOCKOPT,
 	BPF_PROG_TYPE_TRACING,
 	BPF_PROG_TYPE_STRUCT_OPS,
+	BPF_PROG_TYPE_LSM,
 };
 
 enum bpf_attach_type {
@@ -205,6 +206,7 @@ enum bpf_attach_type {
 	BPF_TRACE_RAW_TP,
 	BPF_TRACE_FENTRY,
 	BPF_TRACE_FEXIT,
+	BPF_LSM_MAC,
 	__MAX_BPF_ATTACH_TYPE
 };
 
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f9db72a96ec0..2945739618c9 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2151,6 +2151,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 	case BPF_LIRC_MODE2:
 		ptype = BPF_PROG_TYPE_LIRC_MODE2;
 		break;
+	case BPF_LSM_MAC:
+		ptype = BPF_PROG_TYPE_LSM;
+		break;
 	case BPF_FLOW_DISSECTOR:
 		ptype = BPF_PROG_TYPE_FLOW_DISSECTOR;
 		break;
@@ -2182,6 +2185,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 	case BPF_PROG_TYPE_LIRC_MODE2:
 		ret = lirc_prog_attach(attr, prog);
 		break;
+	case BPF_PROG_TYPE_LSM:
+		ret = -EINVAL;
+		break;
 	case BPF_PROG_TYPE_FLOW_DISSECTOR:
 		ret = skb_flow_dissector_bpf_prog_attach(attr, prog);
 		break;
diff --git a/security/bpf/Makefile b/security/bpf/Makefile
index 26a0ab6f99b7..c78a8a056e7e 100644
--- a/security/bpf/Makefile
+++ b/security/bpf/Makefile
@@ -2,4 +2,4 @@
 #
 # Copyright 2019 Google LLC.
 
-obj-$(CONFIG_SECURITY_BPF) := lsm.o
+obj-$(CONFIG_SECURITY_BPF) := lsm.o ops.o
diff --git a/security/bpf/ops.c b/security/bpf/ops.c
new file mode 100644
index 000000000000..81c2bd9c0495
--- /dev/null
+++ b/security/bpf/ops.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2019 Google LLC.
+ */
+
+#include <linux/filter.h>
+#include <linux/bpf.h>
+
+const struct bpf_prog_ops lsm_prog_ops = {
+};
+
+static const struct bpf_func_proto *get_bpf_func_proto(
+	enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+	switch (func_id) {
+	case BPF_FUNC_map_lookup_elem:
+		return &bpf_map_lookup_elem_proto;
+	case BPF_FUNC_get_current_pid_tgid:
+		return &bpf_get_current_pid_tgid_proto;
+	default:
+		return NULL;
+	}
+}
+
+const struct bpf_verifier_ops lsm_verifier_ops = {
+	.get_func_proto = get_bpf_func_proto,
+};
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 52966e758fe5..b6a725a8a21d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -176,6 +176,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_CGROUP_SOCKOPT,
 	BPF_PROG_TYPE_TRACING,
 	BPF_PROG_TYPE_STRUCT_OPS,
+	BPF_PROG_TYPE_LSM,
 };
 
 enum bpf_attach_type {
@@ -205,6 +206,7 @@ enum bpf_attach_type {
 	BPF_TRACE_RAW_TP,
 	BPF_TRACE_FENTRY,
 	BPF_TRACE_FEXIT,
+	BPF_LSM_MAC,
 	__MAX_BPF_ATTACH_TYPE
 };
 
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 8cc992bc532a..2314889369cc 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -107,6 +107,7 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
 	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 	case BPF_PROG_TYPE_TRACING:
 	case BPF_PROG_TYPE_STRUCT_OPS:
+	case BPF_PROG_TYPE_LSM:
 	default:
 		break;
 	}
-- 
2.20.1