Re: [PATCH v5 02/11] block: Block Device Filtering Mechanism

[Yu Kuai]

Hi,

在 2023/07/11 10:02, Yu Kuai 写道:

> > +static bool submit_bio_filter(struct bio *bio)
> > +{
> > +    if (bio_flagged(bio, BIO_FILTERED))
> > +        return false;
> > +
> > +    bio_set_flag(bio, BIO_FILTERED);
> > +    return bio->bi_bdev->bd_filter->ops->submit_bio(bio);
> > +}
> > +
> >   static void __submit_bio(struct bio *bio)
> >   {
> > +    /*
> > +     * If there is a filter driver attached, check if the BIO needs 
> > to go to
> > +     * the filter driver first, which can then pass on the bio or 
> > consume it.
> > +     */
> > +    if (bio->bi_bdev->bd_filter && submit_bio_filter(bio))
> > +        return;
> > +
> >       if (unlikely(!blk_crypto_bio_prep(&bio)))
> >           return;

...

> > +static void __blkfilter_detach(struct block_device *bdev)
> > +{
> > +    struct blkfilter *flt = bdev->bd_filter;
> > +    const struct blkfilter_operations *ops = flt->ops;
> > +
> > +    bdev->bd_filter = NULL;
> > +    ops->detach(flt);
> > +    module_put(ops->owner);
> > +}
> > +
> > +void blkfilter_detach(struct block_device *bdev)
> > +{
> > +    if (bdev->bd_filter) {
> > +        blk_mq_freeze_queue(bdev->bd_queue);

And this is not sate as well, for bio-based device, q_usage_counter is
not grabbed while submit_bio_filter() is called, hence there is a risk
of uaf from submit_bio_filter().

Thanks,
Kuai