kernel/linux.git/drivers/md/dm-crypt.c, branch v5.15.7

dm crypt: use in_hardirq() instead of deprecated in_irq()

2021-08-20T20:25:07+00:00

Signed-off-by: Changbin Du Signed-off-by: Mike Snitzer

dm crypt: Avoid percpu_counter spinlock contention in crypt_page_alloc()

2021-08-18T06:10:48+00:00

On systems with many cores using dm-crypt, heavy spinlock contention in percpu_counter_compare() can be observed when the page allocation limit for a given device is reached or close to be reached. This is due to percpu_counter_compare() taking a spinlock to compute an exact result on potentially many CPUs at the same time. Switch to non-exact comparison of allocated and allowed pages by using the value returned by percpu_counter_read_positive() to avoid taking the percpu_counter spinlock. This may over/under estimate the actual number of allocated pages by at most (batch-1) * num_online_cpus(). Currently, batch is bounded by 32. The system on which this issue was first observed has 256 CPUs and 512GB of RAM. With a 4k page size, this change may over/under estimate by 31MB. With ~10G (2%) allowed dm-crypt allocations, this seems an acceptable error. Certainly preferred over running into the spinlock contention. This behavior was reproduced on an EC2 c5.24xlarge instance with 96 CPUs and 192GB RAM as follows, but can be provoked on systems with less CPUs as well. * Disable swap * Tune vm settings to promote regular writeback $ echo 50 > /proc/sys/vm/dirty_expire_centisecs $ echo 25 > /proc/sys/vm/dirty_writeback_centisecs $ echo $((128 * 1024 * 1024)) > /proc/sys/vm/dirty_background_bytes * Create 8 dmcrypt devices based on files on a tmpfs * Create and mount an ext4 filesystem on each crypt devices * Run stress-ng --hdd 8 within one of above filesystems Total %system usage collected from sysstat goes to ~35%. Write throughput on the underlying loop device is ~2GB/s. perf profiling an individual kworker kcryptd thread shows the following profile, indicating spinlock contention in percpu_counter_compare(): 99.98% 0.00% kworker/u193:46 [kernel.kallsyms] [k] ret_from_fork | --ret_from_fork kthread worker_thread | --99.92%--process_one_work | |--80.52%--kcryptd_crypt | | | |--62.58%--mempool_alloc | | | | | --62.24%--crypt_page_alloc | | | | | --61.51%--__percpu_counter_compare | | | | | --61.34%--__percpu_counter_sum | | | | | |--58.68%--_raw_spin_lock_irqsave | | | | | | | --58.30%--native_queued_spin_lock_slowpath | | | | | --0.69%--cpumask_next | | | | | --0.51%--_find_next_bit | | | |--10.61%--crypt_convert | | | | | |--6.05%--xts_crypt ... After applying this patch and running the same test, %system usage is lowered to ~7% and write throughput on the loop device increases to ~2.7GB/s. perf report shows mempool_alloc() as ~8% rather than ~62% in the profile and not hitting the percpu_counter() spinlock anymore. |--8.15%--mempool_alloc | | | |--3.93%--crypt_page_alloc | | | | | --3.75%--__alloc_pages | | | | | --3.62%--get_page_from_freelist | | | | | --3.22%--rmqueue_bulk | | | | | --2.59%--_raw_spin_lock | | | | | --2.57%--native_queued_spin_lock_slowpath | | | --3.05%--_raw_spin_lock_irqsave | | | --2.49%--native_queued_spin_lock_slowpath Suggested-by: DJ Gregor Reviewed-by: Mikulas Patocka Signed-off-by: Arne Welzel Fixes: 5059353df86e ("dm crypt: limit the number of allocated pages") Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer

dm: update target status functions to support IMA measurement

2021-08-10T17:34:23+00:00

For device mapper targets to take advantage of IMA's measurement capabilities, the status functions for the individual targets need to be updated to handle the status_type_t case for value STATUSTYPE_IMA. Update status functions for the following target types, to log their respective attributes to be measured using IMA. 01. cache 02. crypt 03. integrity 04. linear 05. mirror 06. multipath 07. raid 08. snapshot 09. striped 10. verity For rest of the targets, handle the STATUSTYPE_IMA case by setting the measurement buffer to NULL. For IMA to measure the data on a given system, the IMA policy on the system needs to be updated to have the following line, and the system needs to be restarted for the measurements to take effect. /etc/ima/ima-policy measure func=CRITICAL_DATA label=device-mapper template=ima-buf The measurements will be reflected in the IMA logs, which are located at: /sys/kernel/security/integrity/ima/ascii_runtime_measurements /sys/kernel/security/integrity/ima/binary_runtime_measurements These IMA logs can later be consumed by various attestation clients running on the system, and send them to external services for attesting the system. The DM target data measured by IMA subsystem can alternatively be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with DM_TABLE_STATUS_CMD. Signed-off-by: Tushar Sugandhi Signed-off-by: Mike Snitzer

dm crypt: Fix zoned block device support

2021-06-04T16:07:38+00:00

Zone append BIOs (REQ_OP_ZONE_APPEND) always specify the start sector of the zone to be written instead of the actual sector location to write. The write location is determined by the device and returned to the host upon completion of the operation. This interface, while simple and efficient for writing into sequential zones of a zoned block device, is incompatible with the use of sector values to calculate a cypher block IV. All data written in a zone end up using the same IV values corresponding to the first sectors of the zone, but read operation will specify any sector within the zone resulting in an IV mismatch between encryption and decryption. To solve this problem, report to DM core that zone append operations are not supported. This result in the zone append operations being emulated using regular write operations. Reported-by: Shin'ichiro Kawasaki Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Himanshu Madhani Signed-off-by: Mike Snitzer

dm: Introduce dm_report_zones()

2021-06-04T16:07:32+00:00

To simplify the implementation of the report_zones operation of a zoned target, introduce the function dm_report_zones() to set a target mapping start sector in struct dm_report_zones_args and call blkdev_report_zones(). This new function is exported and the report zones callback function dm_report_zones_cb() is not. dm-linear, dm-flakey and dm-crypt are modified to use dm_report_zones(). Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn Reviewed-by: Hannes Reinecke Reviewed-by: Himanshu Madhani Signed-off-by: Mike Snitzer

block: rename BIO_MAX_PAGES to BIO_MAX_VECS

2021-03-11T14:47:48+00:00

Ever since the addition of multipage bio_vecs BIO_MAX_PAGES has been horribly confusingly misnamed. Rename it to BIO_MAX_VECS to stop confusing users of the bio API. Signed-off-by: Christoph Hellwig Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Martin K. Petersen Link: https://lore.kernel.org/r/20210311110137.1132391-2-hch@lst.de Signed-off-by: Jens Axboe

dm: fix deadlock when swapping to encrypted device

2021-02-11T14:45:28+00:00

The system would deadlock when swapping to a dm-crypt device. The reason is that for each incoming write bio, dm-crypt allocates memory that holds encrypted data. These excessive allocations exhaust all the memory and the result is either deadlock or OOM trigger. This patch limits the number of in-flight swap bios, so that the memory consumed by dm-crypt is limited. The limit is enforced if the target set the "limit_swap_bios" variable and if the bio has REQ_SWAP set. Non-swap bios are not affected becuase taking the semaphore would cause performance degradation. This is similar to request-based drivers - they will also block when the number of requests is over the limit. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer

dm: simplify target code conditional on CONFIG_BLK_DEV_ZONED

2021-02-11T14:45:27+00:00

Allow removal of CONFIG_BLK_DEV_ZONED conditionals in target_type definition of various targets. Suggested-by: Eric Biggers Signed-off-by: Mike Snitzer

dm crypt: support using trusted keys

2021-02-03T15:13:00+00:00

Commit 27f5411a718c ("dm crypt: support using encrypted keys") extended dm-crypt to allow use of "encrypted" keys along with "user" and "logon". Along the same lines, teach dm-crypt to support "trusted" keys as well. Signed-off-by: Ahmad Fatoum Signed-off-by: Mike Snitzer

dm crypt: replaced #if defined with IS_ENABLED

2021-02-03T15:12:31+00:00

IS_ENABLED(CONFIG_ENCRYPTED_KEYS) is true whether the option is built-in or a module, so use it instead of #if defined checking for each separately. The other #if was to avoid a static function defined, but unused warning. As we now always build the callsite when the function is defined, we can remove that first #if guard. Suggested-by: Arnd Bergmann Signed-off-by: Ahmad Fatoum Acked-by: Dmitry Baryshkov Signed-off-by: Mike Snitzer