[PATCH bpf-next v5 1/7] bpf: Introduce BPF_PROG_TYPE_LSM

KP Singh
2020-03-23T16:44:35Z

From: KP Singh <kpsingh@google.com>

Introduce types and configs for bpf programs that can be attached to
LSM hooks. The programs can be enabled by the config option
CONFIG_BPF_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>
---
MAINTAINERS | 1 +
include/linux/bpf.h | 3 +++
include/linux/bpf_types.h | 4 ++++
include/uapi/linux/bpf.h | 2 ++
init/Kconfig | 10 ++++++++++
kernel/bpf/Makefile | 1 +
kernel/bpf/bpf_lsm.c | 17 +++++++++++++++++
kernel/trace/bpf_trace.c | 12 ++++++------
tools/include/uapi/linux/bpf.h | 2 ++
tools/lib/bpf/libbpf_probes.c | 1 +
10 files changed, 47 insertions(+), 6 deletions(-)
create mode 100644 kernel/bpf/bpf_lsm.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5dbee41045bc..3197fe9256b2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3147,6 +3147,7 @@ R: Martin KaFai Lau <kafai@fb.com>
R: Song Liu <songliubraving@fb.com>
R: Yonghong Song <yhs@fb.com>
R: Andrii Nakryiko <andriin@fb.com>
+R: KP Singh <kpsingh@chromium.org>
L: netdev@vger.kernel.org
L: bpf@vger.kernel.org
T: git git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index bdb981c204fa..af81ec7b783c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1513,6 +1513,9 @@ extern const struct bpf_func_proto bpf_tcp_sock_proto;
extern const struct bpf_func_proto bpf_jiffies64_proto;
extern const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto;

+const struct bpf_func_proto *bpf_tracing_func_proto(
+ enum bpf_func_id func_id, const struct bpf_prog *prog);
+
/* Shared helpers among cBPF and eBPF. */
void bpf_user_rnd_init_once(void);
u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index c81d4ece79a4..ba0c2d56f8a3 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_BPF_LSM
+BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm,
+ void *, void *)
+#endif /* CONFIG_BPF_LSM */
#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 5d01c5c7e598..9f2673c58788 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 {
@@ -211,6 +212,7 @@ enum bpf_attach_type {
BPF_TRACE_FENTRY,
BPF_TRACE_FEXIT,
BPF_MODIFY_RETURN,
+ BPF_LSM_MAC,
__MAX_BPF_ATTACH_TYPE
};

diff --git a/init/Kconfig b/init/Kconfig
index 20a6ac33761c..b2c9a833bc58 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1616,6 +1616,16 @@ config KALLSYMS_BASE_RELATIVE
# end of the "standard kernel features (expert users)" menu

# syscall, maps, verifier
+
+config BPF_LSM
+ bool "LSM Instrumentation with BPF"
+ depends on BPF_SYSCALL
+ help
+ Enables instrumentation of the security hooks with eBPF programs for
+ implementing dynamic MAC and Audit Policies.
+
+ If you are unsure how to answer this question, answer N.
+
config BPF_SYSCALL
bool "Enable bpf() system call"
select BPF
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 046ce5d98033..f2d7be596966 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -29,4 +29,5 @@ obj-$(CONFIG_DEBUG_INFO_BTF) += sysfs_btf.o
endif
ifeq ($(CONFIG_BPF_JIT),y)
obj-$(CONFIG_BPF_SYSCALL) += bpf_struct_ops.o
+obj-${CONFIG_BPF_LSM} += bpf_lsm.o
endif
diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
new file mode 100644
index 000000000000..82875039ca90
--- /dev/null
+++ b/kernel/bpf/bpf_lsm.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2020 Google LLC.
+ */
+
+#include <linux/filter.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+
+const struct bpf_prog_ops lsm_prog_ops = {
+};
+
+const struct bpf_verifier_ops lsm_verifier_ops = {
+ .get_func_proto = bpf_tracing_func_proto,
+ .is_valid_access = btf_ctx_access,
+};
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index e619eedb5919..37ffceab608f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -779,8 +779,8 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = {
.arg1_type = ARG_ANYTHING,
};

-static const struct bpf_func_proto *
-tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+const struct bpf_func_proto *
+bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_map_lookup_elem:
@@ -865,7 +865,7 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_override_return_proto;
#endif
default:
- return tracing_func_proto(func_id, prog);
+ return bpf_tracing_func_proto(func_id, prog);
}
}

@@ -975,7 +975,7 @@ tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_tp;
default:
- return tracing_func_proto(func_id, prog);
+ return bpf_tracing_func_proto(func_id, prog);
}
}

@@ -1082,7 +1082,7 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_read_branch_records:
return &bpf_read_branch_records_proto;
default:
- return tracing_func_proto(func_id, prog);
+ return bpf_tracing_func_proto(func_id, prog);
}
}

@@ -1210,7 +1210,7 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_raw_tp;
default:
- return tracing_func_proto(func_id, prog);
+ return bpf_tracing_func_proto(func_id, prog);
}
}

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 5d01c5c7e598..9f2673c58788 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 {
@@ -211,6 +212,7 @@ enum bpf_attach_type {
BPF_TRACE_FENTRY,
BPF_TRACE_FEXIT,
BPF_MODIFY_RETURN,
+ 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;
}
--
2.20.1