[PATCH 5.10 076/122] dm-crypt: dont modify the data when using authenticated encryption

Greg Kroah-Hartman
2024-02-27T14:30:14Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit 50c70240097ce41fe6bce6478b80478281e4d0f7 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-crypt.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2064,6 +2064,12 @@ static void kcryptd_crypt_write_convert(
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);