[bpf-next,v3,03/10] bpf: lsm: Introduce types for eBPF based LSM
diff mbox series

Message ID 20200123152440.28956-4-kpsingh@chromium.org
State New
Headers show
Series
  • MAC and Audit policy using eBPF (KRSI)
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Commit Message

KP Singh Jan. 23, 2020, 3:24 p.m. UTC
From: KP Singh <kpsingh@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@google.com>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Florent Revest <revest@google.com>
Reviewed-by: Thomas Garnier <thgarnie@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

Comments

Alexei Starovoitov Feb. 10, 2020, 11:58 p.m. UTC | #1
On Thu, Jan 23, 2020 at 07:24:33AM -0800, KP Singh wrote:
> +
> +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,
> +};

Why artificially limit it like this?
It will cause a lot of churn in the future. Like allowing map update and
delete, in addition to lookup, will be an obvious next step.
I think allowing tracing_func_proto() from the start is cleaner.
KP Singh Feb. 11, 2020, 12:44 p.m. UTC | #2
On 10-Feb 15:58, Alexei Starovoitov wrote:
> On Thu, Jan 23, 2020 at 07:24:33AM -0800, KP Singh wrote:
> > +
> > +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,
> > +};
> 
> Why artificially limit it like this?
> It will cause a lot of churn in the future. Like allowing map update and
> delete, in addition to lookup, will be an obvious next step.
> I think allowing tracing_func_proto() from the start is cleaner.

Sure, I will replace it to use tracing_func_proto in the next
revision.

- KP

Patch
diff mbox series

diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index c81d4ece79a4..c36790b202e3 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -70,6 +70,10 @@  BPF_PROG_TYPE(BPF_PROG_TYPE_STRUCT_OPS, bpf_struct_ops,
 	      void *, void *)
 BPF_PROG_TYPE(BPF_PROG_TYPE_EXT, bpf_extension,
 	      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 f1d74a2bd234..2f1e24a8c4a4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -181,6 +181,7 @@  enum bpf_prog_type {
 	BPF_PROG_TYPE_TRACING,
 	BPF_PROG_TYPE_STRUCT_OPS,
 	BPF_PROG_TYPE_EXT,
+	BPF_PROG_TYPE_LSM,
 };
 
 enum bpf_attach_type {
@@ -210,6 +211,7 @@  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 a91ad518c050..eab4a36ee889 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2396,6 +2396,9 @@  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;
@@ -2427,6 +2430,9 @@  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 = -EOPNOTSUPP;
+		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 f1d74a2bd234..2f1e24a8c4a4 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -181,6 +181,7 @@  enum bpf_prog_type {
 	BPF_PROG_TYPE_TRACING,
 	BPF_PROG_TYPE_STRUCT_OPS,
 	BPF_PROG_TYPE_EXT,
+	BPF_PROG_TYPE_LSM,
 };
 
 enum bpf_attach_type {
@@ -210,6 +211,7 @@  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 b782ebef6ac9..2c92059c0c90 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -108,6 +108,7 @@  probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
 	case BPF_PROG_TYPE_TRACING:
 	case BPF_PROG_TYPE_STRUCT_OPS:
 	case BPF_PROG_TYPE_EXT:
+	case BPF_PROG_TYPE_LSM:
 	default:
 		break;
 	}