Re: [PATCH 0/2] ntfs: enforce the encrypted-file policy on the read paths

[Namjae Jeon]

On Mon, Oct 12, 2026 at 3:20 PM Zhan Xusheng <zhanxusheng1024@xxxxxxxxx> wrote:
>
> From: Zhan Xusheng <zhanxusheng@xxxxxxxxxx>
>
> EFS-encrypted attributes are refused with -EOPNOTSUPP in exactly one
> place, ntfs_read_folio(), because decryption is not implemented.  Two
> read paths get there without passing that test and return the raw
> on-disk ciphertext instead, so the same read returns either ciphertext
> or -EOPNOTSUPP depending on which path serves it.
>
> Patch 1 is readahead, which marks the folios uptodate so ->read_folio
> is never called.  read(), mmap(), splice() and fadvise() all populate
> the page cache this way, so one test closes all four.
>
> Patch 2 is direct I/O, which bypasses the page cache entirely and has
> no such backstop.
>
> Both commits are in v7.1.  I have not added Cc: stable; returning
> ciphertext rather than an error is a correctness bug but not a
> privilege boundary crossing, so that call is better made by the
> maintainers.
>
> Found by reading the code.  I have no EFS-encrypted NTFS volume, so
> there is no reproducer; the paths were traced in the source.
>
> Zhan Xusheng (2):
>   ntfs: do not read ahead encrypted files
>   ntfs: reject direct I/O reads of encrypted files
Applied them to #ntfs-next.
Thanks!