On Wed, Sep 09, 2020 at 11:44:22PM +0000, Satya Tangirala wrote: > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > dm-linear and dm-flakey obviously can pass through inline crypto support. > > dm-zero should declare that it passes through inline crypto support, since > any reads from dm-zero should return zeroes, and blk-crypto should not > attempt to decrypt data returned from dm-zero. > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > Co-developed-by: Satya Tangirala <satyat@xxxxxxxxxx> > Signed-off-by: Satya Tangirala <satyat@xxxxxxxxxx> > --- > drivers/md/dm-flakey.c | 1 + > drivers/md/dm-linear.c | 1 + > drivers/md/dm-zero.c | 1 + > 3 files changed, 3 insertions(+) > > diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c > index a2cc9e45cbba..655286dacc35 100644 > --- a/drivers/md/dm-flakey.c > +++ b/drivers/md/dm-flakey.c > @@ -253,6 +253,7 @@ static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv) > ti->num_discard_bios = 1; > ti->per_io_data_size = sizeof(struct per_bio_data); > ti->private = fc; > + ti->may_passthrough_inline_crypto = true; > return 0; > > bad: > diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c > index e1db43446327..6d81878e2ca8 100644 > --- a/drivers/md/dm-linear.c > +++ b/drivers/md/dm-linear.c > @@ -62,6 +62,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv) > ti->num_secure_erase_bios = 1; > ti->num_write_same_bios = 1; > ti->num_write_zeroes_bios = 1; > + ti->may_passthrough_inline_crypto = true; > ti->private = lc; > return 0; > > diff --git a/drivers/md/dm-zero.c b/drivers/md/dm-zero.c > index b65ca8dcfbdc..07e02f3a9cd1 100644 > --- a/drivers/md/dm-zero.c > +++ b/drivers/md/dm-zero.c > @@ -26,6 +26,7 @@ static int zero_ctr(struct dm_target *ti, unsigned int argc, char **argv) > * Silently drop discards, avoiding -EOPNOTSUPP. > */ > ti->num_discard_bios = 1; > + ti->may_passthrough_inline_crypto = true; > > return 0; > } Isn't it wrong to set may_passthrough_inline_crypto on dm-zero? First, there's no actual underlying device associated with dm-zero, so the idea of dm-zero "passing through" anything is strange. Second, inline encryption is supposed to semantically operate on the original bio. I.e. if someone reads some data from dm-zero and they use a bio_crypt_ctx that indicates the data should be decrypted, then I'd expect that either the bio would fail, *or* it would return back data which is equal to the decryption of the all-zeroes ciphertexts. may_passthrough_inline_crypto=false would give that behavior. Whereas with may_passthrough_inline_crypto=true, the bio's encryption context may just be ignored and reads will return all zeroes. Of course, setting an encryption context for I/O to/from dm-zero isn't really something that people would do anyway... But it seems we shouldn't bother setting may_passthrough_inline_crypto on it when it seems wrong. - Eric
