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Message-ID: <2ab36e73-a612-76a8-9c20-f5e11c67bcc3@huaweicloud.com>
Date: Wed, 12 Jul 2023 20:34:57 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Yu Kuai <yukuai1@...weicloud.com>,
Sergei Shtepa <sergei.shtepa@...am.com>, axboe@...nel.dk,
hch@...radead.org, corbet@....net, snitzer@...nel.org
Cc: viro@...iv.linux.org.uk, brauner@...nel.org, dchinner@...hat.com,
willy@...radead.org, dlemoal@...nel.org, linux@...ssschuh.net,
jack@...e.cz, ming.lei@...hat.com, linux-block@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
Donald Buczek <buczek@...gen.mpg.de>,
"yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v5 02/11] block: Block Device Filtering Mechanism
Hi,
在 2023/07/12 18:04, Yu Kuai 写道:
> 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().
And there is another question, can blkfilter_detach() from
del_gendisk/delete_partiton and ioctl concurrent? I think it's a
problem.
Thanks,
Kuai
>
> Thanks,
> Kuai
>
> .
>
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