diff options
| author | Mike Snitzer <snitzer@redhat.com> | 2014-10-04 20:55:32 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-10-04 20:55:32 +0400 |
| commit | b277da0a8a594308e17881f4926879bd5fca2a2d (patch) | |
| tree | 1af7df6ade218a4b246dd43a0771701a672c6cb8 /drivers/scsi/sd.c | |
| parent | 7b7b7f7e024460cb7d77f8f96b6eb1a8803f94d9 (diff) | |
| download | linux-b277da0a8a594308e17881f4926879bd5fca2a2d.tar.xz | |
block: disable entropy contributions for nonrot devices
Clear QUEUE_FLAG_ADD_RANDOM in all block drivers that set
QUEUE_FLAG_NONROT.
Historically, all block devices have automatically made entropy
contributions. But as previously stated in commit e2e1a148 ("block: add
sysfs knob for turning off disk entropy contributions"):
- On SSD disks, the completion times aren't as random as they
are for rotational drives. So it's questionable whether they
should contribute to the random pool in the first place.
- Calling add_disk_randomness() has a lot of overhead.
There are more reliable sources for randomness than non-rotational block
devices. From a security perspective it is better to err on the side of
caution than to allow entropy contributions from unreliable "random"
sources.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/scsi/sd.c')
| -rw-r--r-- | drivers/scsi/sd.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 2c2041ca4b70..fe67f5c107a2 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -2660,8 +2660,10 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp) rot = get_unaligned_be16(&buffer[4]); - if (rot == 1) + if (rot == 1) { queue_flag_set_unlocked(QUEUE_FLAG_NONROT, sdkp->disk->queue); + queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, sdkp->disk->queue); + } out: kfree(buffer); |