linux-kernel - Re: [PATCH v6] security: Add KUnit tests for kuid_root_in_ns and vfsuid_root_in

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Message-ID: <aWHafb6DujTuEZ7l@mail.hallyn.com>
Date: Fri, 9 Jan 2026 22:50:05 -0600
From: "Serge E. Hallyn" <serge@...lyn.com>
To: Ryan Foster <foster.ryan.r@...il.com>
Cc: serge@...lyn.com, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, paul@...l-moore.com,
	selinux@...r.kernel.org
Subject: Re: [PATCH v6] security: Add KUnit tests for kuid_root_in_ns and
 vfsuid_root_in_currentns

On Wed, Jan 07, 2026 at 01:51:28PM -0800, Ryan Foster wrote:
> 
> Here's v6 with both fixes combined. The Dec 29 version you have in caps-next 
> is correct for the namespace config - v6 keeps that and adds the KUNIT=y 
> dependency to fix the Intel CI build error.
> 
> Changes in v6:
> - Namespace config: all three namespaces are independent children of 
>   init_user_ns (same as Dec 29 you reviewed)
>   
> - Build fix: depends on KUNIT=y prevents link errors when KUNIT=m
> 
> The Dec 30 patch accidentally reverted the namespace fix when I was adding the 
> KUNIT=y part. This v6 has both fixes working together.
> 
> Thanks, Ryan
> 
> Add comprehensive KUnit tests for the namespace-related capability
> functions that Serge Hallyn refactored in commit 9891d2f79a9f
> ("Clarify the rootid_owns_currentns").
> 
> The tests verify:
> - Basic functionality: UID 0 in init namespace, invalid vfsuid,
>   non-zero UIDs
> - Actual namespace traversal: Creating user namespaces with different
>   UID mappings where uid 0 maps to different kuids (e.g., 1000, 2000,
>   3000)
> - Hierarchy traversal: Testing multiple nested namespaces to verify
>   correct namespace hierarchy traversal
> 
> This addresses the feedback to "test the actual functionality" by
> creating real user namespaces with different values for the
> namespace's uid 0, rather than just basic input validation.
> 
> The test file is included at the end of commoncap.c when
> CONFIG_SECURITY_COMMONCAP_KUNIT_TEST is enabled, following the
> standard kernel pattern (e.g., scsi_lib.c, ext4/mballoc.c). This
> allows tests to access static functions in the same compilation unit
> without modifying production code based on test configuration.
> 
> The tests require CONFIG_USER_NS to be enabled since they rely on user
> namespace mapping functionality. The Kconfig dependency ensures the
> tests only build when this requirement is met.
> 
> All 7 tests pass:
> - test_vfsuid_root_in_currentns_init_ns
> - test_vfsuid_root_in_currentns_invalid
> - test_vfsuid_root_in_currentns_nonzero
> - test_kuid_root_in_ns_init_ns_uid0
> - test_kuid_root_in_ns_init_ns_nonzero
> - test_kuid_root_in_ns_with_mapping
> - test_kuid_root_in_ns_with_different_mappings
> 
> Updated MAINTAINER capabilities to include commoncap test
> 
> Signed-off-by: Ryan Foster <foster.ryan.r@...il.com>

Thanks, applied to git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux.git #caps-next