landlock: Set up the security framework and manage credentials

mainline inclusion
from mainline-v5.13-rc1
commit 385975dc
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6DJU0
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=385975dca53eb41031d0cbd1de318eb1bc5d6bb9



--------------------------------

Process's credentials point to a Landlock domain, which is underneath
implemented with a ruleset.  In the following commits, this domain is
used to check and enforce the ptrace and filesystem security policies.
A domain is inherited from a parent to its child the same way a thread
inherits a seccomp policy.

Cc: James Morris <jmorris@namei.org>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Jann Horn <jannh@google.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-4-mic@digikod.net


Signed-off-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Yi Yang <yiyang13@huawei.com>