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

From: KP Singh
Date: Wed Jan 15 2020 - 12:13:29 EST


From: KP Singh <kpsingh@xxxxxxxxxx>

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@xxxxxxxxxx>
---
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