On 6/23/2025 7:21 PM, David Hildenbrand wrote:

On 20.06.25 09:03, Shivank Garg wrote:

quoted

Export anon_inode_make_secure_inode() to allow KVM guest_memfd to create
anonymous inodes with proper security context. This replaces the current
pattern of calling alloc_anon_inode() followed by
inode_init_security_anon() for creating security context manually.

This change also fixes a security regression in secretmem where the
S_PRIVATE flag was not cleared after alloc_anon_inode(), causing
LSM/SELinux checks to be bypassed for secretmem file descriptors.

As guest_memfd currently resides in the KVM module, we need to export this
symbol for use outside the core kernel. In the future, guest_memfd might be
moved to core-mm, at which point the symbols no longer would have to be
exported. When/if that happens is still unclear.

Fixes: 2bfe15c52612 ("mm: create security context for memfd_secret inodes")
Suggested-by: David Hildenbrand <redacted>
Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Shivank Garg <redacted>

In general, LGTM, but I think the actual fix should be separated from exporting it for guest_memfd purposes?

Also makes backporting easier, when EXPORT_SYMBOL_GPL_FOR_MODULES does not exist yet ...

I agree. I did not think about backporting conflicts when sending the patch.

Christian, I can send it as 2 separate patches to make it easier?

Thanks,
Shivank