[PATCH net-next v7 05/10] landlock: Add LSM hooks related to filesystem

From: "Mickaël Salaün" <mic@digikod.net>
To: linux-kernel@vger.kernel.org
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Arnaldo Carvalho de Melo" <acme@kernel.org>,
	"Casey Schaufler" <casey@schaufler-ca.com>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"David Drysdale" <drysdale@google.com>,
	"David S . Miller" <davem@davemloft.net>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	"James Morris" <james.l.morris@oracle.com>,
	"Jann Horn" <jann@thejh.net>, "Jonathan Corbet" <corbet@lwn.net>,
	"Matthew Garrett" <mjg59@srcf.ucam.org>,
	"Michael Kerrisk" <mtk.manpages@gmail.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Paul Moore" <paul@paul-moore.com>,
	"Sargun Dhillon" <sargun@sargun.me>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	"Shuah Khan" <shuah@kernel.org>, "Tejun Heo" <tj@kernel.org>,
	"Thomas Graf" <tgraf@suug.ch>, "Will Drewry" <wad@chromium.org>,
	kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
	linux-security-module@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH net-next v7 05/10] landlock: Add LSM hooks related to filesystem
Date: Mon, 21 Aug 2017 02:09:28 +0200	[thread overview]
Message-ID: <20170821000933.13024-6-mic@digikod.net> (raw)
In-Reply-To: <20170821000933.13024-1-mic@digikod.net>

Handle 33 filesystem-related LSM hooks for the Landlock filesystem
event: LANDLOCK_SUBTYPE_EVENT_FS.

A Landlock event wrap LSM hooks for similar kernel object types (e.g.
struct file, struct path...). Multiple LSM hooks can trigger the same
Landlock event.

Landlock handle nine coarse-grained actions: read, write, execute, new,
get, remove, ioctl, lock and fcntl. Each of them abstract LSM hook
access control in a way that can be extended in the future.

The Landlock LSM hook registration is done after other LSM to only run
actions from user-space, via eBPF programs, if the access was granted by
major (privileged) LSMs.

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---

Changes since v6:
* add 3 more sub-events: IOCTL, LOCK, FCNTL
  https://lkml.kernel.org/r/2fbc99a6-f190-f335-bd14-04bdeed35571@digikod.net
* use the new security_add_hooks()
* explain the -Werror=unused-function
* constify pointers
* cleanup headers

Changes since v5:
* split hooks.[ch] into hooks.[ch] and hooks_fs.[ch]
* add more documentation
* cosmetic fixes
* rebase (SCALAR_VALUE)

Changes since v4:
* add LSM hook abstraction called Landlock event
  * use the compiler type checking to verify hooks use by an event
  * handle all filesystem related LSM hooks (e.g. file_permission,
    mmap_file, sb_mount...)
* register BPF programs for Landlock just after LSM hooks registration
* move hooks registration after other LSMs
* add failsafes to check if a hook is not used by the kernel
* allow partial raw value access form the context (needed for programs
  generated by LLVM)

Changes since v3:
* split commit
* add hooks dealing with struct inode and struct path pointers:
  inode_permission and inode_getattr
* add abstraction over eBPF helper arguments thanks to wrapping structs
---
 include/linux/lsm_hooks.h    |   5 +
 security/landlock/Makefile   |   7 +-
 security/landlock/common.h   |   2 +
 security/landlock/hooks.c    |  83 ++++++
 security/landlock/hooks.h    | 177 +++++++++++++
 security/landlock/hooks_fs.c | 586 +++++++++++++++++++++++++++++++++++++++++++
 security/landlock/hooks_fs.h |  19 ++
 security/landlock/init.c     |  10 +
 security/security.c          |  12 +-
 9 files changed, 899 insertions(+), 2 deletions(-)
 create mode 100644 security/landlock/hooks.c
 create mode 100644 security/landlock/hooks.h
 create mode 100644 security/landlock/hooks_fs.c
 create mode 100644 security/landlock/hooks_fs.h

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 3a90febadbe2..7614c3d66265 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1982,5 +1982,10 @@ void __init loadpin_add_hooks(void);
 #else
 static inline void loadpin_add_hooks(void) { };
 #endif
+#ifdef CONFIG_SECURITY_LANDLOCK
+extern void __init landlock_add_hooks(void);
+#else
+static inline void __init landlock_add_hooks(void) { }
+#endif /* CONFIG_SECURITY_LANDLOCK */
 
 #endif /* ! __LINUX_LSM_HOOKS_H */
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index 7205f9a7a2ee..b382be409b3b 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -1,3 +1,8 @@
+# Catch defined but unused hooks, e.g. error out if a HOOK_NEW_FS(foo) is not
+# used with a HOOK_INIT_FS(foo) in the struct security_hook_list
+# landlock_hooks.
+ccflags-$(CONFIG_SECURITY_LANDLOCK) += -Werror=unused-function
+
 obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
 
-landlock-y := init.o
+landlock-y := init.o hooks.o hooks_fs.o
diff --git a/security/landlock/common.h b/security/landlock/common.h
index c82cbd3fb640..a69c35231d35 100644
--- a/security/landlock/common.h
+++ b/security/landlock/common.h
@@ -18,4 +18,6 @@
  */
 #define LANDLOCK_ABI 1
 
+#define LANDLOCK_NAME "landlock"
+
 #endif /* _SECURITY_LANDLOCK_COMMON_H */
diff --git a/security/landlock/hooks.c b/security/landlock/hooks.c
new file mode 100644
index 000000000000..b48caeb0a49a
--- /dev/null
+++ b/security/landlock/hooks.c
@@ -0,0 +1,83 @@
+/*
+ * Landlock LSM - hook helpers
+ *
+ * Copyright © 2016-2017 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/current.h>
+#include <linux/bpf.h> /* enum bpf_access_type, struct landlock_context */
+#include <linux/errno.h>
+#include <linux/filter.h> /* BPF_PROG_RUN() */
+#include <linux/rculist.h> /* list_add_tail_rcu */
+#include <linux/stddef.h> /* offsetof */
+
+#include "hooks.h" /* CTX_ARG_NB */
+
+
+bool landlock_is_valid_access(int off, int size, enum bpf_access_type type,
+		enum bpf_reg_type *reg_type,
+		enum bpf_reg_type ctx_types[CTX_ARG_NB],
+		const union bpf_prog_subtype *prog_subtype)
+{
+	int max_size;
+
+	if (type != BPF_READ)
+		return false;
+	if (off < 0 || off >= sizeof(struct landlock_context))
+		return false;
+	if (size <= 0 || size > sizeof(__u64))
+		return false;
+
+	/* set max size */
+	switch (off) {
+	case offsetof(struct landlock_context, status):
+	case offsetof(struct landlock_context, event):
+	case offsetof(struct landlock_context, arg1):
+	case offsetof(struct landlock_context, arg2):
+		max_size = sizeof(__u64);
+		break;
+	default:
+		return false;
+	}
+
+	/* set register type */
+	switch (off) {
+	case offsetof(struct landlock_context, arg1):
+		*reg_type = ctx_types[0];
+		break;
+	case offsetof(struct landlock_context, arg2):
+		*reg_type = ctx_types[1];
+		break;
+	default:
+		*reg_type = SCALAR_VALUE;
+	}
+
+	/* check memory range access */
+	switch (*reg_type) {
+	case NOT_INIT:
+		return false;
+	case SCALAR_VALUE:
+		/* allow partial raw value */
+		if (size > max_size)
+			return false;
+		break;
+	default:
+		/* deny partial pointer */
+		if (size != max_size)
+			return false;
+	}
+
+	return true;
+}
+
+int landlock_decide(enum landlock_subtype_event event,
+		__u64 ctx_values[CTX_ARG_NB], const char *hook)
+{
+	bool deny = false;
+
+	return deny ? -EPERM : 0;
+}
diff --git a/security/landlock/hooks.h b/security/landlock/hooks.h
new file mode 100644
index 000000000000..51957211b67d
--- /dev/null
+++ b/security/landlock/hooks.h
@@ -0,0 +1,177 @@
+/*
+ * Landlock LSM - hooks helpers
+ *
+ * Copyright © 2016-2017 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/current.h>
+#include <linux/bpf.h> /* enum bpf_access_type */
+#include <linux/lsm_hooks.h>
+#include <linux/sched.h> /* struct task_struct */
+
+/* separators */
+#define SEP_COMMA() ,
+#define SEP_SPACE()
+#define SEP_AND() &&
+
+#define MAP2x1(s, m, x1, x2, ...) m(x1, x2)
+#define MAP2x2(s, m, x1, x2, ...) m(x1, x2) s() MAP2x1(s, m, __VA_ARGS__)
+#define MAP2x3(s, m, x1, x2, ...) m(x1, x2) s() MAP2x2(s, m, __VA_ARGS__)
+#define MAP2x4(s, m, x1, x2, ...) m(x1, x2) s() MAP2x3(s, m, __VA_ARGS__)
+#define MAP2x5(s, m, x1, x2, ...) m(x1, x2) s() MAP2x4(s, m, __VA_ARGS__)
+#define MAP2x6(s, m, x1, x2, ...) m(x1, x2) s() MAP2x5(s, m, __VA_ARGS__)
+#define MAP2x(n, ...) MAP2x##n(__VA_ARGS__)
+
+#define MAP1x1(s, m, x1, ...) m(x1)
+#define MAP1x2(s, m, x1, ...) m(x1) s() MAP1x1(s, m, __VA_ARGS__)
+#define MAP1x(n, ...) MAP1x##n(__VA_ARGS__)
+
+#define SKIP2x1(x1, x2, ...) __VA_ARGS__
+#define SKIP2x2(x1, x2, ...) SKIP2x1(__VA_ARGS__)
+#define SKIP2x3(x1, x2, ...) SKIP2x2(__VA_ARGS__)
+#define SKIP2x4(x1, x2, ...) SKIP2x3(__VA_ARGS__)
+#define SKIP2x5(x1, x2, ...) SKIP2x4(__VA_ARGS__)
+#define SKIP2x6(x1, x2, ...) SKIP2x5(__VA_ARGS__)
+#define SKIP2x(n, ...) SKIP2x##n(__VA_ARGS__)
+
+/* LSM hook argument helpers */
+#define MAP_HOOK_COMMA(n, ...) MAP2x(n, SEP_COMMA, __VA_ARGS__)
+
+#define GET_HOOK_TA(t, a) t a
+
+/* Landlock event argument helpers  */
+#define MAP_EVENT_COMMA(h, n, m, ...) MAP2x(n, SEP_COMMA, m, SKIP2x(h, __VA_ARGS__))
+#define MAP_EVENT_SPACE(h, n, m, ...) MAP2x(n, SEP_SPACE, m, SKIP2x(h, __VA_ARGS__))
+#define MAP_EVENT_AND(h, n, m, ...) MAP2x(n, SEP_AND, m, SKIP2x(h, __VA_ARGS__))
+
+#define EXPAND_TYPE(d) d##_TYPE
+#define EXPAND_BPF(d) d##_BPF
+#define EXPAND_C(d) d##_C
+
+#define GET_TYPE_BPF(t) EXPAND_BPF(t)
+#define GET_TYPE_C(t) EXPAND_C(t) *
+
+#define GET_EVENT_C(d, a) GET_TYPE_C(EXPAND_TYPE(d))
+#define GET_EVENT_U64(d, a) ((u64)(d##_VAL(a)))
+#define GET_EVENT_DEC(d, a) d##_DEC(a)
+#define GET_EVENT_OK(d, a) d##_OK(a)
+
+/**
+ * HOOK_ACCESS
+ *
+ * @EVENT: Landlock event name
+ * @NA: number of event arguments
+ *
+ * The __consistent_##EVENT() extern functions and __wrapcheck_* types are
+ * useful to catch inconsistencies in LSM hook definitions thanks to the
+ * compiler type checking.
+ */
+#define HOOK_ACCESS(EVENT, NA, ...)					\
+	inline bool landlock_is_valid_access_event_##EVENT(		\
+			int off, int size, enum bpf_access_type type,	\
+			enum bpf_reg_type *reg_type,			\
+			const union bpf_prog_subtype *prog_subtype)	\
+	{								\
+		enum bpf_reg_type _ctx_types[CTX_ARG_NB] = {		\
+			MAP1x(NA, SEP_COMMA, GET_TYPE_BPF, __VA_ARGS__)	\
+		};							\
+		return landlock_is_valid_access(off, size, type,	\
+				reg_type, _ctx_types, prog_subtype);	\
+	}								\
+	extern void __consistent_##EVENT(				\
+			MAP1x(NA, SEP_COMMA, GET_TYPE_C, __VA_ARGS__))
+
+/**
+ * HOOK_NEW
+ *
+ * @INST: event instance for this hook
+ * @EVENT: Landlock event name
+ * @NE: number of event arguments
+ * @HOOK: LSM hook name
+ * @NH: number of hook arguments
+ */
+#define HOOK_NEW(INST, EVENT, NE, HOOK, NH, ...)			\
+	static int landlock_hook_##EVENT##_##HOOK##_##INST(		\
+			MAP_HOOK_COMMA(NH, GET_HOOK_TA, __VA_ARGS__))	\
+	{								\
+		if (!landlocked(current))				\
+			return 0;					\
+		if (!(MAP_EVENT_AND(NH, NE, GET_EVENT_OK,		\
+						__VA_ARGS__)))		\
+			return 0;					\
+		{							\
+		MAP_EVENT_SPACE(NH, NE, GET_EVENT_DEC, __VA_ARGS__)	\
+		__u64 _ctx_values[CTX_ARG_NB] = {			\
+			MAP_EVENT_COMMA(NH, NE, GET_EVENT_U64,		\
+					__VA_ARGS__)			\
+		};							\
+		return landlock_decide(LANDLOCK_SUBTYPE_EVENT_##EVENT,	\
+				_ctx_values, #HOOK);			\
+		}							\
+	}								\
+	extern void __consistent_##EVENT(MAP_EVENT_COMMA(		\
+				NH, NE, GET_EVENT_C, __VA_ARGS__))
+
+#define HOOK_INIT(EVENT, HOOK, ID) \
+	LSM_HOOK_INIT(HOOK, landlock_hook_##EVENT##_##HOOK##_##ID)
+
+/*
+ * The WRAP_TYPE_* definitions group the bpf_reg_type enum value and the C
+ * type. This C type may remains unused except to catch inconsistencies in LSM
+ * hook definitions thanks to the compiler type checking.
+ */
+
+/* WRAP_TYPE_NONE */
+#define WRAP_TYPE_NONE_BPF	NOT_INIT
+#define WRAP_TYPE_NONE_C	struct __wrapcheck_none
+WRAP_TYPE_NONE_C;
+
+/* WRAP_TYPE_RAW */
+#define WRAP_TYPE_RAW_BPF	SCALAR_VALUE
+#define WRAP_TYPE_RAW_C		struct __wrapcheck_raw
+WRAP_TYPE_RAW_C;
+
+/*
+ * The WRAP_ARG_* definitions group the LSM hook argument type (C and BPF), the
+ * wrapping struct declaration (if any) and the value to copy to the BPF
+ * context. This definitions may be used thanks to the EXPAND_* helpers.
+ *
+ * WRAP_ARG_*_TYPE: type for BPF and C (cf. WRAP_TYPE_*)
+ * WRAP_ARG_*_DEC: declare a wrapper
+ * WRAP_ARG_*_VAL: get this wrapper's address
+ * WRAP_ARG_*_OK: check if the argument is usable
+ */
+
+/* WRAP_ARG_NONE */
+#define WRAP_ARG_NONE_TYPE	WRAP_TYPE_NONE
+#define WRAP_ARG_NONE_DEC(arg)
+#define WRAP_ARG_NONE_VAL(arg)	0
+#define WRAP_ARG_NONE_OK(arg)	(!WARN_ON(true))
+
+/* WRAP_ARG_RAW */
+#define WRAP_ARG_RAW_TYPE	WRAP_TYPE_RAW
+#define WRAP_ARG_RAW_DEC(arg)
+#define WRAP_ARG_RAW_VAL(arg)	arg
+#define WRAP_ARG_RAW_OK(arg)	(true)
+
+
+#define CTX_ARG_NB 2
+
+static inline bool landlocked(const struct task_struct *task)
+{
+	return false;
+}
+
+__init void landlock_register_hooks(struct security_hook_list *hooks, int count);
+
+bool landlock_is_valid_access(int off, int size, enum bpf_access_type type,
+		enum bpf_reg_type *reg_type,
+		enum bpf_reg_type ctx_types[CTX_ARG_NB],
+		const union bpf_prog_subtype *prog_subtype);
+
+int landlock_decide(enum landlock_subtype_event event,
+		__u64 ctx_values[CTX_ARG_NB], const char *hook);
diff --git a/security/landlock/hooks_fs.c b/security/landlock/hooks_fs.c
new file mode 100644
index 000000000000..fa80b35a269d
--- /dev/null
+++ b/security/landlock/hooks_fs.c
@@ -0,0 +1,586 @@
+/*
+ * Landlock LSM - filesystem hooks
+ *
+ * Copyright © 2016-2017 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h> /* ARRAY_SIZE */
+#include <linux/lsm_hooks.h>
+#include <linux/types.h> /* uintptr_t */
+
+/* permissions translation */
+#include <linux/fs.h> /* MAY_* */
+#include <linux/mman.h> /* PROT_* */
+
+/* hook arguments */
+#include <linux/cred.h>
+#include <linux/dcache.h> /* struct dentry */
+#include <linux/fs.h> /* struct inode, struct iattr */
+#include <linux/mm_types.h> /* struct vm_area_struct */
+#include <linux/mount.h> /* struct vfsmount */
+#include <linux/path.h> /* struct path */
+#include <linux/sched.h> /* struct task_struct */
+#include <linux/time.h> /* struct timespec */
+
+#include "common.h"
+#include "hooks.h"
+#include "hooks_fs.h"
+
+
+#define HOOK_NEW_FS(...) HOOK_NEW(1, FS, 2, __VA_ARGS__)
+#define HOOK_NEW_FS2(...) HOOK_NEW(2, FS, 2, __VA_ARGS__)
+#define HOOK_NEW_FS3(...) HOOK_NEW(3, FS, 2, __VA_ARGS__)
+#define HOOK_NEW_FS4(...) HOOK_NEW(4, FS, 2, __VA_ARGS__)
+
+#define HOOK_INIT_FS(HOOK) HOOK_INIT(FS, HOOK, 1)
+#define HOOK_INIT_FS2(HOOK) HOOK_INIT(FS, HOOK, 2)
+#define HOOK_INIT_FS3(HOOK) HOOK_INIT(FS, HOOK, 3)
+#define HOOK_INIT_FS4(HOOK) HOOK_INIT(FS, HOOK, 4)
+
+/* WRAP_TYPE_FS */
+#define WRAP_TYPE_FS_BPF	CONST_PTR_TO_HANDLE_FS
+#define WRAP_TYPE_FS_C		const struct bpf_handle_fs
+
+/* WRAP_ARG_FILE */
+#define WRAP_ARG_FILE_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_FILE_DEC(arg)					\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_FILE, .file = arg };
+#define WRAP_ARG_FILE_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_FILE_OK(arg)	(arg)
+
+/* WRAP_ARG_VMAF */
+#define WRAP_ARG_VMAF_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_VMAF_DEC(arg)					\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_FILE, .file = arg->vm_file };
+#define WRAP_ARG_VMAF_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_VMAF_OK(arg)	(arg && arg->vm_file)
+
+/* WRAP_ARG_INODE */
+#define WRAP_ARG_INODE_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_INODE_DEC(arg)					\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_INODE, .inode = arg };
+#define WRAP_ARG_INODE_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_INODE_OK(arg)	(arg)
+
+/* WRAP_ARG_PATH */
+#define WRAP_ARG_PATH_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_PATH_DEC(arg)					\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_PATH, .path = arg };
+#define WRAP_ARG_PATH_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_PATH_OK(arg)	(arg)
+
+/* WRAP_ARG_DENTRY */
+#define WRAP_ARG_DENTRY_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_DENTRY_DEC(arg)				\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_DENTRY, .dentry = arg };
+#define WRAP_ARG_DENTRY_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_DENTRY_OK(arg)	(arg)
+
+/* WRAP_ARG_SB */
+#define WRAP_ARG_SB_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_SB_DEC(arg)					\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_DENTRY, .dentry = arg->s_root };
+#define WRAP_ARG_SB_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_SB_OK(arg)	(arg && arg->s_root)
+
+/* WRAP_ARG_MNTROOT */
+#define WRAP_ARG_MNTROOT_TYPE	WRAP_TYPE_FS
+#define WRAP_ARG_MNTROOT_DEC(arg)				\
+	EXPAND_C(WRAP_TYPE_FS) wrap_##arg =			\
+	{ .type = BPF_HANDLE_FS_TYPE_DENTRY, .dentry = arg->mnt_root };
+#define WRAP_ARG_MNTROOT_VAL(arg)	((uintptr_t)&wrap_##arg)
+#define WRAP_ARG_MNTROOT_OK(arg)	(arg && arg->mnt_root)
+
+
+static inline u64 fs_may_to_access(int fs_may)
+{
+	u64 ret = 0;
+
+	if (fs_may & MAY_EXEC)
+		ret |= LANDLOCK_ACTION_FS_EXEC;
+	if (fs_may & MAY_READ)
+		ret |= LANDLOCK_ACTION_FS_READ;
+	if (fs_may & MAY_WRITE)
+		ret |= LANDLOCK_ACTION_FS_WRITE;
+	if (fs_may & MAY_APPEND)
+		ret |= LANDLOCK_ACTION_FS_WRITE;
+	if (fs_may & MAY_OPEN)
+		ret |= LANDLOCK_ACTION_FS_GET;
+	/* ignore MAY_CHDIR and MAY_ACCESS */
+
+	return ret;
+}
+
+static u64 mem_prot_to_access(unsigned long prot, bool private)
+{
+	u64 ret = 0;
+
+	/* private mapping do not write to files */
+	if (!private && (prot & PROT_WRITE))
+		ret |= LANDLOCK_ACTION_FS_WRITE;
+	if (prot & PROT_READ)
+		ret |= LANDLOCK_ACTION_FS_READ;
+	if (prot & PROT_EXEC)
+		ret |= LANDLOCK_ACTION_FS_EXEC;
+
+	return ret;
+}
+
+/* hook definitions */
+
+HOOK_ACCESS(FS, 2, WRAP_TYPE_FS, WRAP_TYPE_RAW);
+
+/* binder_* hooks */
+
+HOOK_NEW_FS(binder_transfer_file, 3,
+	struct task_struct *, from,
+	struct task_struct *, to,
+	struct file *, file,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+/* sb_* hooks */
+
+HOOK_NEW_FS(sb_statfs, 1,
+	struct dentry *, dentry,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+/*
+ * Being able to mount on a path means being able to override the underlying
+ * filesystem view of this path, hence the need for a write access right.
+ */
+HOOK_NEW_FS(sb_mount, 5,
+	const char *, dev_name,
+	const struct path *, path,
+	const char *, type,
+	unsigned long, flags,
+	void *, data,
+	WRAP_ARG_PATH, path,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS(sb_remount, 2,
+	struct super_block *, sb,
+	void *, data,
+	WRAP_ARG_SB, sb,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS(sb_umount, 2,
+	struct vfsmount *, mnt,
+	int, flags,
+	WRAP_ARG_MNTROOT, mnt,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+/*
+ * The old_path is similar to a destination mount point.
+ */
+HOOK_NEW_FS(sb_pivotroot, 2,
+	const struct path *, old_path,
+	const struct path *, new_path,
+	WRAP_ARG_PATH, old_path,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+/* inode_* hooks */
+
+/* a directory inode contains only one dentry */
+HOOK_NEW_FS(inode_create, 3,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	umode_t, mode,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_create, 3,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	umode_t, mode,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_NEW
+);
+
+HOOK_NEW_FS(inode_link, 3,
+	struct dentry *, old_dentry,
+	struct inode *, dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_DENTRY, old_dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+HOOK_NEW_FS2(inode_link, 3,
+	struct dentry *, old_dentry,
+	struct inode *, dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS3(inode_link, 3,
+	struct dentry *, old_dentry,
+	struct inode *, dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_DENTRY, new_dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_NEW
+);
+
+HOOK_NEW_FS(inode_unlink, 2,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_unlink, 2,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_REMOVE
+);
+
+HOOK_NEW_FS(inode_symlink, 3,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	const char *, old_name,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_symlink, 3,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	const char *, old_name,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_NEW
+);
+
+HOOK_NEW_FS(inode_mkdir, 3,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	umode_t, mode,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_mkdir, 3,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	umode_t, mode,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_NEW
+);
+
+HOOK_NEW_FS(inode_rmdir, 2,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_rmdir, 2,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_REMOVE
+);
+
+HOOK_NEW_FS(inode_mknod, 4,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	umode_t, mode,
+	dev_t, dev,
+	WRAP_ARG_INODE, dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_mknod, 4,
+	struct inode *, dir,
+	struct dentry *, dentry,
+	umode_t, mode,
+	dev_t, dev,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_NEW
+);
+
+HOOK_NEW_FS(inode_rename, 4,
+	struct inode *, old_dir,
+	struct dentry *, old_dentry,
+	struct inode *, new_dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_INODE, old_dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS2(inode_rename, 4,
+	struct inode *, old_dir,
+	struct dentry *, old_dentry,
+	struct inode *, new_dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_DENTRY, old_dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_REMOVE
+);
+
+HOOK_NEW_FS3(inode_rename, 4,
+	struct inode *, old_dir,
+	struct dentry *, old_dentry,
+	struct inode *, new_dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_INODE, new_dir,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS4(inode_rename, 4,
+	struct inode *, old_dir,
+	struct dentry *, old_dentry,
+	struct inode *, new_dir,
+	struct dentry *, new_dentry,
+	WRAP_ARG_DENTRY, new_dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_NEW
+);
+
+HOOK_NEW_FS(inode_readlink, 1,
+	struct dentry *, dentry,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+// XXX: handle inode?
+HOOK_NEW_FS(inode_follow_link, 3,
+	struct dentry *, dentry,
+	struct inode *, inode,
+	bool, rcu,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+HOOK_NEW_FS(inode_permission, 2,
+	struct inode *, inode,
+	int, mask,
+	WRAP_ARG_INODE, inode,
+	WRAP_ARG_RAW, fs_may_to_access(mask)
+);
+
+HOOK_NEW_FS(inode_setattr, 2,
+	struct dentry *, dentry,
+	struct iattr *, attr,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS(inode_getattr, 1,
+	const struct path *, path,
+	WRAP_ARG_PATH, path,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+HOOK_NEW_FS(inode_setxattr, 5,
+	struct dentry *, dentry,
+	const char *, name,
+	const void *, value,
+	size_t, size,
+	int, flags,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS(inode_getxattr, 2,
+	struct dentry *, dentry,
+	const char *, name,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+HOOK_NEW_FS(inode_listxattr, 1,
+	struct dentry *, dentry,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+HOOK_NEW_FS(inode_removexattr, 2,
+	struct dentry *, dentry,
+	const char *, name,
+	WRAP_ARG_DENTRY, dentry,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+HOOK_NEW_FS(inode_getsecurity, 4,
+	struct inode *, inode,
+	const char *, name,
+	void **, buffer,
+	bool, alloc,
+	WRAP_ARG_INODE, inode,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_READ
+);
+
+HOOK_NEW_FS(inode_setsecurity, 5,
+	struct inode *, inode,
+	const char *, name,
+	const void *, value,
+	size_t, size,
+	int, flag,
+	WRAP_ARG_INODE, inode,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_WRITE
+);
+
+/* file_* hooks */
+
+HOOK_NEW_FS(file_permission, 2,
+	struct file *, file,
+	int, mask,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, fs_may_to_access(mask)
+);
+
+/*
+ * An ioctl command can be a read or a write. This can be checked with _IOC*()
+ * for some commands but a Landlock rule should check the ioctl command to
+ * whitelist them.
+ */
+HOOK_NEW_FS(file_ioctl, 3,
+	struct file *, file,
+	unsigned int, cmd,
+	unsigned long, arg,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_IOCTL
+);
+
+HOOK_NEW(1, FS_IOCTL, 2, file_ioctl, 3,
+	struct file *, file,
+	unsigned int, cmd,
+	unsigned long, arg,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, cmd
+);
+
+HOOK_NEW_FS(file_lock, 2,
+	struct file *, file,
+	unsigned int, cmd,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_LOCK
+);
+
+HOOK_NEW(1, FS_LOCK, 2, file_lock, 2,
+	struct file *, file,
+	unsigned int, cmd,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, cmd
+);
+
+HOOK_NEW_FS(file_fcntl, 3,
+	struct file *, file,
+	unsigned int, cmd,
+	unsigned long, arg,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_FCNTL
+);
+
+HOOK_NEW(1, FS_FCNTL, 2, file_fcntl, 3,
+	struct file *, file,
+	unsigned int, cmd,
+	unsigned long, arg,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, cmd
+);
+
+HOOK_NEW_FS(mmap_file, 4,
+	struct file *, file,
+	unsigned long, reqprot,
+	unsigned long, prot,
+	unsigned long, flags,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, mem_prot_to_access(prot, flags & MAP_PRIVATE)
+);
+
+HOOK_NEW_FS(file_mprotect, 3,
+	struct vm_area_struct *, vma,
+	unsigned long, reqprot,
+	unsigned long, prot,
+	WRAP_ARG_VMAF, vma,
+	WRAP_ARG_RAW, mem_prot_to_access(prot, !(vma->vm_flags & VM_SHARED))
+);
+
+HOOK_NEW_FS(file_receive, 1,
+	struct file *, file,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_GET
+);
+
+HOOK_NEW_FS(file_open, 2,
+	struct file *, file,
+	const struct cred *, cred,
+	WRAP_ARG_FILE, file,
+	WRAP_ARG_RAW, LANDLOCK_ACTION_FS_GET
+);
+
+static struct security_hook_list landlock_hooks[] = {
+	HOOK_INIT_FS(binder_transfer_file),
+
+	HOOK_INIT_FS(sb_statfs),
+	HOOK_INIT_FS(sb_mount),
+	HOOK_INIT_FS(sb_remount),
+	HOOK_INIT_FS(sb_umount),
+	HOOK_INIT_FS(sb_pivotroot),
+
+	HOOK_INIT_FS(inode_create),
+	HOOK_INIT_FS2(inode_create),
+	HOOK_INIT_FS(inode_link),
+	HOOK_INIT_FS2(inode_link),
+	HOOK_INIT_FS3(inode_link),
+	HOOK_INIT_FS(inode_unlink),
+	HOOK_INIT_FS2(inode_unlink),
+	HOOK_INIT_FS(inode_symlink),
+	HOOK_INIT_FS2(inode_symlink),
+	HOOK_INIT_FS(inode_mkdir),
+	HOOK_INIT_FS2(inode_mkdir),
+	HOOK_INIT_FS(inode_rmdir),
+	HOOK_INIT_FS2(inode_rmdir),
+	HOOK_INIT_FS(inode_mknod),
+	HOOK_INIT_FS2(inode_mknod),
+	HOOK_INIT_FS(inode_rename),
+	HOOK_INIT_FS2(inode_rename),
+	HOOK_INIT_FS3(inode_rename),
+	HOOK_INIT_FS4(inode_rename),
+	HOOK_INIT_FS(inode_readlink),
+	HOOK_INIT_FS(inode_follow_link),
+	HOOK_INIT_FS(inode_permission),
+	HOOK_INIT_FS(inode_setattr),
+	HOOK_INIT_FS(inode_getattr),
+	HOOK_INIT_FS(inode_setxattr),
+	HOOK_INIT_FS(inode_getxattr),
+	HOOK_INIT_FS(inode_listxattr),
+	HOOK_INIT_FS(inode_removexattr),
+	HOOK_INIT_FS(inode_getsecurity),
+	HOOK_INIT_FS(inode_setsecurity),
+
+	HOOK_INIT_FS(file_permission),
+	HOOK_INIT_FS(file_ioctl),
+	HOOK_INIT(FS_IOCTL, file_ioctl, 1),
+	HOOK_INIT_FS(file_lock),
+	HOOK_INIT(FS_LOCK, file_lock, 1),
+	HOOK_INIT_FS(file_fcntl),
+	HOOK_INIT(FS_FCNTL, file_fcntl, 1),
+	HOOK_INIT_FS(mmap_file),
+	HOOK_INIT_FS(file_mprotect),
+	HOOK_INIT_FS(file_receive),
+	HOOK_INIT_FS(file_open),
+};
+
+__init void landlock_add_hooks_fs(void)
+{
+	security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), LANDLOCK_NAME);
+}
diff --git a/security/landlock/hooks_fs.h b/security/landlock/hooks_fs.h
new file mode 100644
index 000000000000..aab07c018f38
--- /dev/null
+++ b/security/landlock/hooks_fs.h
@@ -0,0 +1,19 @@
+/*
+ * Landlock LSM - filesystem hooks
+ *
+ * Copyright © 2017 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bpf.h> /* enum bpf_access_type */
+
+
+bool landlock_is_valid_access_event_FS(
+		int off, int size, enum bpf_access_type type,
+		enum bpf_reg_type *reg_type,
+		const union bpf_prog_subtype *prog_subtype);
+
+__init void landlock_add_hooks_fs(void);
diff --git a/security/landlock/init.c b/security/landlock/init.c
index 09acbc74abd6..1e6660fed697 100644
--- a/security/landlock/init.c
+++ b/security/landlock/init.c
@@ -10,8 +10,10 @@
 
 #include <linux/bpf.h> /* enum bpf_access_type */
 #include <linux/capability.h> /* capable */
+#include <linux/lsm_hooks.h>
 
 #include "common.h" /* LANDLOCK_* */
+#include "hooks_fs.h"
 
 
 static inline bool bpf_landlock_is_valid_access(int off, int size,
@@ -23,6 +25,8 @@ static inline bool bpf_landlock_is_valid_access(int off, int size,
 
 	switch (prog_subtype->landlock_rule.event) {
 	case LANDLOCK_SUBTYPE_EVENT_FS:
+		return landlock_is_valid_access_event_FS(off, size, type,
+				&info->reg_type, prog_subtype);
 	case LANDLOCK_SUBTYPE_EVENT_UNSPEC:
 	default:
 		return false;
@@ -113,3 +117,9 @@ const struct bpf_verifier_ops bpf_landlock_ops = {
 	.is_valid_access = bpf_landlock_is_valid_access,
 	.is_valid_subtype = bpf_landlock_is_valid_subtype,
 };
+
+void __init landlock_add_hooks(void)
+{
+	pr_info("%s: ABI %u", LANDLOCK_NAME, LANDLOCK_ABI);
+	landlock_add_hooks_fs();
+}
diff --git a/security/security.c b/security/security.c
index 30132378d103..000d95d53902 100644
--- a/security/security.c
+++ b/security/security.c
@@ -75,10 +75,20 @@ int __init security_init(void)
 	loadpin_add_hooks();
 
 	/*
-	 * Load all the remaining security modules.
+	 * Load all remaining privileged security modules.
 	 */
 	do_security_initcalls();
 
+	/*
+	 * Load potentially-unprivileged security modules at the end.
+	 *
+	 * For an unprivileged access-control, we don't want to give the
+	 * ability to any process to do some checks (e.g. through an eBPF
+	 * program) on kernel objects (e.g. files) if a privileged security
+	 * policy forbid their access.
+	 */
+	landlock_add_hooks();
+
 	return 0;
 }
 
-- 
2.14.1
