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Commit 721c7fc7 authored by Ilya Dryomov's avatar Ilya Dryomov Committed by Jens Axboe
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block: fail op_is_write() requests to read-only partitions 



Regular block device writes go through blkdev_write_iter(), which does
bdev_read_only(), while zeroout/discard/etc requests are never checked,
both userspace- and kernel-triggered.  Add a generic catch-all check to
generic_make_request_checks() to actually enforce ioctl(BLKROSET) and
set_disk_ro(), which is used by quite a few drivers for things like
snapshots, read-only backing files/images, etc.

Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 17534c6f

block/blk-core.c

+38 −18
Original line number Diff line number Diff line
@@ -2062,6 +2062,21 @@ static inline bool should_fail_request(struct hd_struct *part, 


#endif /* CONFIG_FAIL_MAKE_REQUEST */



static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)

{

	if (part->policy && op_is_write(bio_op(bio))) {

		char b[BDEVNAME_SIZE];



		printk(KERN_ERR

		       "generic_make_request: Trying to write "

			"to read-only block-device %s (partno %d)\n",

			bio_devname(bio, b), part->partno);

		return true;

	}



	return false;

}



/*

 * Remap block n of partition p to block n+start(p) of the disk.

 */
@@ -2070,27 +2085,28 @@ static inline int blk_partition_remap(struct bio *bio) 
	struct hd_struct *p;

	int ret = 0;



	rcu_read_lock();

	p = __disk_get_part(bio->bi_disk, bio->bi_partno);

	if (unlikely(!p || should_fail_request(p, bio->bi_iter.bi_size) ||

		     bio_check_ro(bio, p))) {

		ret = -EIO;

		goto out;

	}



	/*

	 * Zone reset does not include bi_size so bio_sectors() is always 0.

	 * Include a test for the reset op code and perform the remap if needed.

	 */

	if (!bio->bi_partno ||

	    (!bio_sectors(bio) && bio_op(bio) != REQ_OP_ZONE_RESET))

		return 0;

	if (!bio_sectors(bio) && bio_op(bio) != REQ_OP_ZONE_RESET)

		goto out;



	rcu_read_lock();

	p = __disk_get_part(bio->bi_disk, bio->bi_partno);

	if (likely(p && !should_fail_request(p, bio->bi_iter.bi_size))) {

	bio->bi_iter.bi_sector += p->start_sect;

	bio->bi_partno = 0;

	trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p),

			      bio->bi_iter.bi_sector - p->start_sect);

	} else {

		printk("%s: fail for partition %d\n", __func__, bio->bi_partno);

		ret = -EIO;

	}

	rcu_read_unlock();



out:

	rcu_read_unlock();

	return ret;

}
@@ -2149,15 +2165,19 @@ generic_make_request_checks(struct bio *bio) 
	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP

	 * if queue is not a request based queue.

	 */



	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))

		goto not_supported;



	if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))

		goto end_io;



	if (!bio->bi_partno) {

		if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0)))

			goto end_io;

	} else {

		if (blk_partition_remap(bio))

			goto end_io;

	}



	if (bio_check_eod(bio, nr_sectors))

		goto end_io;