[PATCH bpf-next v5 3/7] bpf: lsm: provide attachment points for BPF LSM programs
From: KP Singh <hidden>
Date: 2020-03-23 16:45:02
Also in:
bpf, lkml
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Linus Torvalds
From: KP Singh <redacted> When CONFIG_BPF_LSM is enabled, nops functions, bpf_lsm_<hook_name>, are generated for each LSM hook. These nops are initialized as LSM hooks in a subsequent patch. Signed-off-by: KP Singh <redacted> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <redacted> --- include/linux/bpf_lsm.h | 21 +++++++++++++++++++++ kernel/bpf/bpf_lsm.c | 19 +++++++++++++++++++ 2 files changed, 40 insertions(+) create mode 100644 include/linux/bpf_lsm.h
diff --git a/include/linux/bpf_lsm.h b/include/linux/bpf_lsm.h
new file mode 100644
index 000000000000..c6423a140220
--- /dev/null
+++ b/include/linux/bpf_lsm.h@@ -0,0 +1,21 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copyright (C) 2020 Google LLC. + */ + +#ifndef _LINUX_BPF_LSM_H +#define _LINUX_BPF_LSM_H + +#include <linux/bpf.h> +#include <linux/lsm_hooks.h> + +#ifdef CONFIG_BPF_LSM + +#define LSM_HOOK(RET, NAME, ...) RET bpf_lsm_##NAME(__VA_ARGS__); +#include <linux/lsm_hook_names.h> +#undef LSM_HOOK + +#endif /* CONFIG_BPF_LSM */ + +#endif /* _LINUX_BPF_LSM_H */
diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
index 82875039ca90..530d137f7a84 100644
--- a/kernel/bpf/bpf_lsm.c
+++ b/kernel/bpf/bpf_lsm.c@@ -7,6 +7,25 @@ #include <linux/filter.h> #include <linux/bpf.h> #include <linux/btf.h> +#include <linux/lsm_hooks.h> +#include <linux/bpf_lsm.h> + +/* For every LSM hook that allows attachment of BPF programs, declare a NOP + * function where a BPF program can be attached as an fexit trampoline. + */ +#define LSM_HOOK(RET, NAME, ...) LSM_HOOK_##RET(NAME, __VA_ARGS__) + +#define LSM_HOOK_int(NAME, ...) \ +noinline __weak int bpf_lsm_##NAME(__VA_ARGS__) \ +{ \ + return 0; \ +} + +#define LSM_HOOK_void(NAME, ...) \ +noinline __weak void bpf_lsm_##NAME(__VA_ARGS__) {} + +#include <linux/lsm_hook_names.h> +#undef LSM_HOOK const struct bpf_prog_ops lsm_prog_ops = { };
--
2.20.1