On Wed, Sep 14, 2016 at 09:24:15AM +0200, Mickaël Salaün wrote:

Add a basic sandbox tool to create a process isolated from some part of
the system. This can depend of the current cgroup.

Example with the current process hierarchy (seccomp):

  $ ls /home
  user1
  $ LANDLOCK_ALLOWED='/bin:/lib:/usr:/tmp:/proc/self/fd/0' \
      ./samples/landlock/sandbox /bin/sh -i
  Launching a new sandboxed process.
  $ ls /home
  ls: cannot open directory '/home': Permission denied

Example with a cgroup:

  $ mkdir /sys/fs/cgroup/sandboxed
  $ ls /home
  user1
  $ LANDLOCK_CGROUPS='/sys/fs/cgroup/sandboxed' \
      LANDLOCK_ALLOWED='/bin:/lib:/usr:/tmp:/proc/self/fd/0' \
      ./samples/landlock/sandbox
  Ready to sandbox with cgroups.
  $ ls /home
  user1
  $ echo $$ > /sys/fs/cgroup/sandboxed/cgroup.procs
  $ ls /home
  ls: cannot open directory '/home': Permission denied

Changes since v2:
* use BPF_PROG_ATTACH for cgroup handling

Signed-off-by: Mickaël Salaün <mic@digikod.net>

...

+	struct bpf_insn hook_path[] = {
+		/* specify an option, if any */
+		BPF_MOV32_IMM(BPF_REG_1, 0),
+		/* handles to compare with */
+		BPF_LD_MAP_FD(BPF_REG_2, map_fs),
+		BPF_MOV64_IMM(BPF_REG_3, BPF_MAP_ARRAY_OP_OR),
+		/* hook argument (struct file) */
+		BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_6, offsetof(struct
+					landlock_data, args[0])),
+		/* checker function */
+		BPF_EMIT_CALL(BPF_FUNC_landlock_cmp_fs_beneath_with_struct_file),

the example is sweet!
Since only that helper is used, could you skip the other one
from the patches (for now) ?