apparmor: disable showing the mode as part of a secid to secctx

Displaying the mode as part of the seectx takes up unnecessary memory,
makes it so we can't use refcounted secctx so we need to alloc/free on
every conversion from secid to secctx and introduces a space that
could be potentially mishandled by tooling.

Eg. In an audit record we get

subj_type=firefix (enforce)

Having the mode reported is not necessary, and might even be confusing
eg. when writing an audit rule to match the above record field you
would use

-F subj_type=firefox

ie. the mode is not included. AppArmor provides ways to find the mode
without reporting as part of the secctx. So disable this by default
before its use is wide spread and we can't. For now we add a sysctl
to control the behavior as we can't guarantee no one is using this.

Acked-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: Convert secid mapping to XArrays instead of IDR

XArrays are a better match than IDR for how AppArmor is mapping
secids. Specifically AppArmor is trying to keep the allocation
dense. XArrays also have the advantage of avoiding the complexity IDRs
preallocation.

In addition this avoids/fixes a lockdep issue raised in the LKML thread
"Linux 5.18-rc4"

where there is a report of an interaction between apparmor and IPC,
this warning may have been spurious as the reported issue is in a
per-cpu local lock taken by the IDR. With the one side in the IPC id
allocation and the other in AppArmor's secid allocation.

Description by John Johansen <john.johansen@canonical.com>

Message-Id: <226cee6a-6ca1-b603-db08-8500cd8f77b7@gnuweeb.org>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 315 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

apparmor: Add a wildcard secid

Reserve a secid value that we can use as a wildcard, allowing us to
define policy that's expected to match against all secids.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: fixup secid map conversion to using IDR

The IDR conversion did not handle an error case for when allocating a
mapping fails, and it did not ensure that mappings did not allocate or
use a 0 value, which is used as an invalid secid. Which is used when a
mapping fails.

Fixes: 3ae7eb49a2be ("apparmor: Use an IDR to allocate apparmor secids")
Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: add support for mapping secids and using secctxes

Use a radix tree to provide a map between the secid and the label,
and along with it a basic ability to provide secctx conversion.

Shared/cached secctx will be added later.

Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: rename sid to secid

Move to common terminology with other LSMs and kernel infrastucture

Signed-off-by: John Johansen <john.johansen@canonical.com>