Re: [PATCH RFC v11 12/19] dm: add finalize hook to target_type

Paul Moore
2023-11-02T00:41:34Z

On Mon, Oct 23, 2023 at 11:52 PM Paul Moore <paul@paul-moore.com> wrote:
> On Oct 4, 2023 Fan Wu <wufan@linux.microsoft.com> wrote:
> >
> > This patch adds a target finalize hook.
> >
> > The hook is triggered just before activating an inactive table of a
> > mapped device. If it returns an error the __bind get cancelled.
> >
> > The dm-verity target will use this hook to attach the dm-verity's
> > roothash metadata to the block_device struct of the mapped device.
> >
> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> > ---
> > v1-v10:
> > + Not present
> > ---
> > drivers/md/dm.c | 12 ++++++++++++
> > include/linux/device-mapper.h | 7 +++++++
> > 2 files changed, 19 insertions(+)
>
> We need an ACK and confirmation from Alasdair and/or Mike that this
> is the right approach.

A gentle ping with a reminder ...

For reference, the full patchset can be found on lore at the link below:

https://lore.kernel.org/linux-security-module/1696457386-3010-1-git-send-email-wufan@linux.microsoft.com/

> > diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> > index 64a1f306c96c..3be9cc35306d 100644
> > --- a/drivers/md/dm.c
> > +++ b/drivers/md/dm.c
> > @@ -2239,6 +2239,18 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
> > goto out;
> > }
> >
> > + for (unsigned int i = 0; i < t->num_targets; i++) {
> > + struct dm_target *ti = dm_table_get_target(t, i);
> > +
> > + if (ti->type->finalize) {
> > + ret = ti->type->finalize(ti);
> > + if (ret) {
> > + old_map = ERR_PTR(ret);
> > + goto out;
> > + }
> > + }
> > + }
> > +
> > old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
> > rcu_assign_pointer(md->map, (void *)t);
> > md->immutable_target_type = dm_table_get_immutable_target_type(t);
> > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> > index 69d0435c7ebb..4040e84a8ec7 100644
> > --- a/include/linux/device-mapper.h
> > +++ b/include/linux/device-mapper.h
> > @@ -160,6 +160,12 @@ typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
> > */
> > typedef size_t (*dm_dax_recovery_write_fn)(struct dm_target *ti, pgoff_t pgoff,
> > void *addr, size_t bytes, struct iov_iter *i);
> > +/*
> > + * Returns:
> > + * < 0 : error
> > + * = 0 : success
> > + */
> > +typedef int (*dm_finalize_fn) (struct dm_target *target);
> >
> > void dm_error(const char *message);
> >
> > @@ -209,6 +215,7 @@ struct target_type {
> > dm_dax_direct_access_fn direct_access;
> > dm_dax_zero_page_range_fn dax_zero_page_range;
> > dm_dax_recovery_write_fn dax_recovery_write;
> > + dm_finalize_fn finalize;
> >
> > /* For internal device-mapper use. */
> > struct list_head list;
> > --
> > 2.25.1

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