dm-crypt: don't modify the data when using authenticated encryption

It was said that authenticated encryption could produce invalid tag when
the data that is being encrypted is modified [1]. So, fix this problem by
copying the data into the clone bio first and then encrypt them inside the
clone bio.

This may reduce performance, but it is needed to prevent the user from
corrupting the device by writing data with O_DIRECT and modifying them at
the same time.

[1] https://lore.kernel.org/all/20240207004723.GA35324@sol.localdomain/T/

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index f745f85..14c5be6 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2071,6 +2071,12 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
        io->ctx.bio_out = clone;
        io->ctx.iter_out = clone->bi_iter;
 
+       if (crypt_integrity_aead(cc)) {
+               bio_copy_data(clone, io->base_bio);
+               io->ctx.bio_in = clone;
+               io->ctx.iter_in = clone->bi_iter;
+       }
+
        sector += bio_sectors(clone);
 
        crypt_inc_pending(io);