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commit b879f915bc48a18d4f4462729192435bb0f17052 upstream.
Record the start_time for a bio but defer the starting block core's IO
accounting until after IO is submitted using bio_start_io_acct_time().
This approach avoids the need to mess around with any of the
individual IO stats in response to a bio_split() that follows bio
submission.
Reported-by: Bud Brown <bubrown@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Depends-on: e45c47d1f94e ("block: add bio_start_io_acct_time() to control start_time")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220128155841.39644-4-snitzer@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f524d9c95fab54783d0038f7a3e8c014d5b56857 upstream.
Reverts a1e1cb72d9649 ("dm: fix redundant IO accounting for bios that
need splitting") because it was too narrow in scope (only addressed
redundant 'sectors[]' accounting and not ios, nsecs[], etc).
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220128155841.39644-3-snitzer@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0c031fd37f69deb0cd8c43bbfcfccd62ebd7e952 upstream.
bioset acct is only needed for raid0 and raid5. Therefore, md_run only
allocates it for raid0 and raid5. However, this does not cover
personality takeover, which may cause uninitialized bioset. For example,
the following repro steps:
mdadm -CR /dev/md0 -l1 -n2 /dev/loop0 /dev/loop1
mdadm --wait /dev/md0
mkfs.xfs /dev/md0
mdadm /dev/md0 --grow -l5
mount /dev/md0 /mnt
causes panic like:
[ 225.933939] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 225.934903] #PF: supervisor instruction fetch in kernel mode
[ 225.935639] #PF: error_code(0x0010) - not-present page
[ 225.936361] PGD 0 P4D 0
[ 225.936677] Oops: 0010 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN PTI
[ 225.937525] CPU: 27 PID: 1133 Comm: mount Not tainted 5.16.0-rc3+ #706
[ 225.938416] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.module_el8.4.0+547+a85d02ba 04/01/2014
[ 225.939922] RIP: 0010:0x0
[ 225.940289] Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
[ 225.941196] RSP: 0018:ffff88815897eff0 EFLAGS: 00010246
[ 225.941897] RAX: 0000000000000000 RBX: 0000000000092800 RCX: ffffffff81370a39
[ 225.942813] RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000092800
[ 225.943772] RBP: 1ffff1102b12fe04 R08: fffffbfff0b43c01 R09: fffffbfff0b43c01
[ 225.944807] R10: ffffffff85a1e007 R11: fffffbfff0b43c00 R12: ffff88810eaaaf58
[ 225.945757] R13: 0000000000000000 R14: ffff88810eaaafb8 R15: ffff88815897f040
[ 225.946709] FS: 00007ff3f2505080(0000) GS:ffff888fb5e00000(0000) knlGS:0000000000000000
[ 225.947814] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 225.948556] CR2: ffffffffffffffd6 CR3: 000000015aa5a006 CR4: 0000000000370ee0
[ 225.949537] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 225.950455] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 225.951414] Call Trace:
[ 225.951787] <TASK>
[ 225.952120] mempool_alloc+0xe5/0x250
[ 225.952625] ? mempool_resize+0x370/0x370
[ 225.953187] ? rcu_read_lock_sched_held+0xa1/0xd0
[ 225.953862] ? rcu_read_lock_bh_held+0xb0/0xb0
[ 225.954464] ? sched_clock_cpu+0x15/0x120
[ 225.955019] ? find_held_lock+0xac/0xd0
[ 225.955564] bio_alloc_bioset+0x1ed/0x2a0
[ 225.956080] ? lock_downgrade+0x3a0/0x3a0
[ 225.956644] ? bvec_alloc+0xc0/0xc0
[ 225.957135] bio_clone_fast+0x19/0x80
[ 225.957651] raid5_make_request+0x1370/0x1b70
[ 225.958286] ? sched_clock_cpu+0x15/0x120
[ 225.958797] ? __lock_acquire+0x8b2/0x3510
[ 225.959339] ? raid5_get_active_stripe+0xce0/0xce0
[ 225.959986] ? lock_is_held_type+0xd8/0x130
[ 225.960528] ? rcu_read_lock_sched_held+0xa1/0xd0
[ 225.961135] ? rcu_read_lock_bh_held+0xb0/0xb0
[ 225.961703] ? sched_clock_cpu+0x15/0x120
[ 225.962232] ? lock_release+0x27a/0x6c0
[ 225.962746] ? do_wait_intr_irq+0x130/0x130
[ 225.963302] ? lock_downgrade+0x3a0/0x3a0
[ 225.963815] ? lock_release+0x6c0/0x6c0
[ 225.964348] md_handle_request+0x342/0x530
[ 225.964888] ? set_in_sync+0x170/0x170
[ 225.965397] ? blk_queue_split+0x133/0x150
[ 225.965988] ? __blk_queue_split+0x8b0/0x8b0
[ 225.966524] ? submit_bio_checks+0x3b2/0x9d0
[ 225.967069] md_submit_bio+0x127/0x1c0
[...]
Fix this by moving alloc/free of acct bioset to pers->run and pers->free.
While we are on this, properly handle md_integrity_register() error in
raid0_run().
Fixes: daee2024715d (md: check level before create and exit io_acct_set)
Cc: stable@vger.kernel.org
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit d751939235b9b7bc4af15f90a3e99288a8b844a7 ]
Make sure ->dax_dev is NULL on error so that the cleanup path doesn't
trip over an ERR_PTR.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211129102203.2243509-2-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit cba23ac158db7f3cd48a923d6861bee2eb7a2978 ]
Corrupted metadata could warrant returning error from sm_ll_lookup_bitmap().
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 85bca3c05b6cca31625437eedf2060e846c4bbad ]
Corrupt metadata could trigger an out of bounds write.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 46669e8616c649c71c4cfcd712fd3d107e771380 upstream.
commit [1] causes missing bitmap updates when there isn't any WriteMostly
devices.
Detailed steps to reproduce by Norbert (which somehow didn't make to lore):
# setup md10 (raid1) with two drives (1 GByte sparse files)
dd if=/dev/zero of=disk1 bs=1024k seek=1024 count=0
dd if=/dev/zero of=disk2 bs=1024k seek=1024 count=0
losetup /dev/loop11 disk1
losetup /dev/loop12 disk2
mdadm --create /dev/md10 --level=1 --raid-devices=2 /dev/loop11 /dev/loop12
# add bitmap (aka write-intent log)
mdadm /dev/md10 --grow --bitmap=internal
echo check > /sys/block/md10/md/sync_action
root:# cat /sys/block/md10/md/mismatch_cnt
0
root:#
# remove member drive disk2 (loop12)
mdadm /dev/md10 -f loop12 ; mdadm /dev/md10 -r loop12
# modify degraded md device
dd if=/dev/urandom of=/dev/md10 bs=512 count=1
# no blocks recorded as out of sync on the remaining member disk1/loop11
root:# mdadm -X /dev/loop11 | grep Bitmap
Bitmap : 16 bits (chunks), 0 dirty (0.0%)
root:#
# re-add disk2, nothing synced because of empty bitmap
mdadm /dev/md10 --re-add /dev/loop12
# check integrity again
echo check > /sys/block/md10/md/sync_action
# disk1 and disk2 are no longer in sync, reads return differend data
root:# cat /sys/block/md10/md/mismatch_cnt
128
root:#
# clean up
mdadm -S /dev/md10
losetup -d /dev/loop11
losetup -d /dev/loop12
rm disk1 disk2
Fix this by moving the WriteMostly check to the if condition for
alloc_behind_master_bio().
[1] commit fd3b6975e9c1 ("md/raid1: only allocate write behind bio for WriteMostly device")
Fixes: fd3b6975e9c1 ("md/raid1: only allocate write behind bio for WriteMostly device")
Cc: stable@vger.kernel.org # v5.12+
Cc: Guoqing Jiang <guoqing.jiang@linux.dev>
Cc: Jens Axboe <axboe@kernel.dk>
Reported-by: Norbert Warmuth <nwarmuth@t-online.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1b8d2789dad0005fd5e7d35dab26a8e1203fb6da upstream.
Move dm_tm_unlock() after dm_tm_dec().
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 55df1ce0d4e086e05a8ab20619c73c729350f965 upstream.
The superblock of version 1.0 doesn't get moved to the new position on a
device size change. This leads to a rdev without a superblock on a known
position, the raid can't be re-assembled.
The line was removed by mistake and is re-added by this patch.
Fixes: d9c0fa509eaf ("md: fix max sectors calculation for super 1.0")
Cc: stable@vger.kernel.org
Signed-off-by: Markus Hochholdinger <markus@hochholdinger.net>
Reviewed-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2878feaed543c35f9dbbe6d8ce36fb67ac803eef upstream.
This reverts commit 2fd3e5efe791946be0957c8e1eed9560b541fe46.
The above commit replaces page_address(bv->bv_page) by bvec_virt(bv) to
avoid directly access to bv->bv_page, but in situation bv->bv_offset is
not zero and page_address(bv->bv_page) is not equal to bvec_virt(bv). In
such case a memory corruption may happen because memory in next page is
tainted by following line in do_btree_node_write(),
memcpy(bvec_virt(bv), addr, PAGE_SIZE);
This patch reverts the mentioned commit to avoid the memory corruption.
Fixes: 2fd3e5efe791 ("bcache: use bvec_virt")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org # 5.15
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211103151041.70516-1-colyli@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8468f45091d2866affed6f6a7aecc20779139173 upstream.
In bcache_device_free(), pointer disk is referenced still in
ida_simple_remove() after blk_cleanup_disk() gets called on this
pointer. This may cause a potential panic by use-after-free on the
disk pointer.
This patch fixes the problem by calling blk_cleanup_disk() after
ida_simple_remove().
Fixes: bc70852fd104 ("bcache: convert to blk_alloc_disk/blk_cleanup_disk")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: stable@vger.kernel.org # v5.14+
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211103064917.67383-1-colyli@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 8b9e2291e355a0eafdd5b1e21a94a6659f24b351 ]
When the in memory flag is changed, we need to persist the change in the
rdev superblock flags. This is needed for "writemostly" and "failfast".
Reviewed-by: Li Feng <fengli@smartx.com>
Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit fd3b6975e9c11c4fa00965f82a0bfbb3b7b44101 upstream.
Commit 6607cd319b6b91bff94e90f798a61c031650b514 ("raid1: ensure write
behind bio has less than BIO_MAX_VECS sectors") tried to guarantee the
size of behind bio is not bigger than BIO_MAX_VECS sectors.
Unfortunately the same calltrace still could happen since an array could
enable write-behind without write mostly device.
To match the manpage of mdadm (which says "write-behind is only attempted
on drives marked as write-mostly"), we need to check WriteMostly flag to
avoid such unexpected behavior.
[1]. https://bugzilla.kernel.org/show_bug.cgi?id=213181#c25
Cc: stable@vger.kernel.org # v5.12+
Cc: Jens Stutte <jens@chianterastutte.eu>
Reported-by: Jens Stutte <jens@chianterastutte.eu>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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dm_io_dec_pending() calls end_io_acct() first and will then dec md
in-flight pending count. But if a task is swapping DM table at same
time this can result in a crash due to mempool->elements being NULL:
task1 task2
do_resume
->do_suspend
->dm_wait_for_completion
bio_endio
->clone_endio
->dm_io_dec_pending
->end_io_acct
->wakeup task1
->dm_swap_table
->__bind
->__bind_mempools
->bioset_exit
->mempool_exit
->free_io
[ 67.330330] Unable to handle kernel NULL pointer dereference at
virtual address 0000000000000000
......
[ 67.330494] pstate: 80400085 (Nzcv daIf +PAN -UAO)
[ 67.330510] pc : mempool_free+0x70/0xa0
[ 67.330515] lr : mempool_free+0x4c/0xa0
[ 67.330520] sp : ffffff8008013b20
[ 67.330524] x29: ffffff8008013b20 x28: 0000000000000004
[ 67.330530] x27: ffffffa8c2ff40a0 x26: 00000000ffff1cc8
[ 67.330535] x25: 0000000000000000 x24: ffffffdada34c800
[ 67.330541] x23: 0000000000000000 x22: ffffffdada34c800
[ 67.330547] x21: 00000000ffff1cc8 x20: ffffffd9a1304d80
[ 67.330552] x19: ffffffdada34c970 x18: 000000b312625d9c
[ 67.330558] x17: 00000000002dcfbf x16: 00000000000006dd
[ 67.330563] x15: 000000000093b41e x14: 0000000000000010
[ 67.330569] x13: 0000000000007f7a x12: 0000000034155555
[ 67.330574] x11: 0000000000000001 x10: 0000000000000001
[ 67.330579] x9 : 0000000000000000 x8 : 0000000000000000
[ 67.330585] x7 : 0000000000000000 x6 : ffffff80148b5c1a
[ 67.330590] x5 : ffffff8008013ae0 x4 : 0000000000000001
[ 67.330596] x3 : ffffff80080139c8 x2 : ffffff801083bab8
[ 67.330601] x1 : 0000000000000000 x0 : ffffffdada34c970
[ 67.330609] Call trace:
[ 67.330616] mempool_free+0x70/0xa0
[ 67.330627] bio_put+0xf8/0x110
[ 67.330638] dec_pending+0x13c/0x230
[ 67.330644] clone_endio+0x90/0x180
[ 67.330649] bio_endio+0x198/0x1b8
[ 67.330655] dec_pending+0x190/0x230
[ 67.330660] clone_endio+0x90/0x180
[ 67.330665] bio_endio+0x198/0x1b8
[ 67.330673] blk_update_request+0x214/0x428
[ 67.330683] scsi_end_request+0x2c/0x300
[ 67.330688] scsi_io_completion+0xa0/0x710
[ 67.330695] scsi_finish_command+0xd8/0x110
[ 67.330700] scsi_softirq_done+0x114/0x148
[ 67.330708] blk_done_softirq+0x74/0xd0
[ 67.330716] __do_softirq+0x18c/0x374
[ 67.330724] irq_exit+0xb4/0xb8
[ 67.330732] __handle_domain_irq+0x84/0xc0
[ 67.330737] gic_handle_irq+0x148/0x1b0
[ 67.330744] el1_irq+0xe8/0x190
[ 67.330753] lpm_cpuidle_enter+0x4f8/0x538
[ 67.330759] cpuidle_enter_state+0x1fc/0x398
[ 67.330764] cpuidle_enter+0x18/0x20
[ 67.330772] do_idle+0x1b4/0x290
[ 67.330778] cpu_startup_entry+0x20/0x28
[ 67.330786] secondary_start_kernel+0x160/0x170
Fix this by:
1) Establishing pointers to 'struct dm_io' members in
dm_io_dec_pending() so that they may be passed into end_io_acct()
_after_ free_io() is called.
2) Moving end_io_acct() after free_io().
Cc: stable@vger.kernel.org
Signed-off-by: Jiazi Li <lijiazi@xiaomi.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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DM uses blk-mq's quiesce/unquiesce to stop/start device mapper queue.
But blk-mq's unquiesce may come from outside events, such as elevator
switch, updating nr_requests or others, and request may come during
suspend, so simply ask for blk-mq to requeue it.
Fixes one kernel panic issue when running updating nr_requests and
dm-mpath suspend/resume stress test.
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Don't populate the read-only array descs on the stack but instead it
static and add extra const. Also makes the object code smaller by 66
bytes:
Before:
text data bss dec hex filename
42382 11140 512 54034 d312 ./drivers/md/dm-clone-target.o
After:
text data bss dec hex filename
42220 11236 512 53968 d2d0 ./drivers/md/dm-clone-target.o
(gcc version 11.2.0)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Without FEC, dm-verity won't call verity_handle_err() when I/O fails,
but with FEC enabled, it currently does even if an I/O error has
occurred.
If there is an I/O error and FEC correction fails, return the error
instead of calling verity_handle_err() again.
Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Akilesh Kailash <akailash@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Commit b0140891a8cea3 ("md: Fix race when creating a new md device.")
not only moved assigning mddev->gendisk before calling add_disk, which
fixes the races described in the commit log, but also added a
mddev->open_mutex critical section over add_disk and creation of the
md kobj. Adding a kobject after add_disk is racy vs deleting the gendisk
right after adding it, but md already prevents against that by holding
a mddev->active reference.
On the other hand taking this lock added a lock order reversal with what
is not disk->open_mutex (used to be bdev->bd_mutex when the commit was
added) for partition devices, which need that lock for the internal open
for the partition scan, and a recent commit also takes it for
non-partitioned devices, leading to further lockdep splatter.
Fixes: b0140891a8ce ("md: Fix race when creating a new md device.")
Fixes: d62633873590 ("block: support delayed holder registration")
Reported-by: syzbot+fadc0aaf497e6a493b9f@syzkaller.appspotmail.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: syzbot+fadc0aaf497e6a493b9f@syzkaller.appspotmail.com
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Song Liu <songliubraving@fb.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm updates from Dan Williams:
- Fix a race condition in the teardown path of raw mode pmem
namespaces.
- Cleanup the code that filesystems use to detect filesystem-dax
capabilities of their underlying block device.
* tag 'libnvdimm-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
dax: remove bdev_dax_supported
xfs: factor out a xfs_buftarg_is_dax helper
dax: stub out dax_supported for !CONFIG_FS_DAX
dax: remove __generic_fsdax_supported
dax: move the dax_read_lock() locking into dax_supported
dax: mark dax_get_by_host static
dm: use fs_dax_get_by_bdev instead of dax_get_by_host
dax: stop using bdevname
fsdax: improve the FS_DAX Kconfig description and help text
libnvdimm/pmem: Fix crash triggered when I/O in-flight during unbind
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git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
Pull integrity subsystem updates from Mimi Zohar:
- Limit the allowed hash algorithms when writing security.ima xattrs or
verifying them, based on the IMA policy and the configured hash
algorithms.
- Return the calculated "critical data" measurement hash and size to
avoid code duplication. (Preparatory change for a proposed LSM.)
- and a single patch to address a compiler warning.
* tag 'integrity-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
IMA: reject unknown hash algorithms in ima_get_hash_algo
IMA: prevent SETXATTR_CHECK policy rules with unavailable algorithms
IMA: introduce a new policy option func=SETXATTR_CHECK
IMA: add a policy option to restrict xattr hash algorithms on appraisal
IMA: add support to restrict the hash algorithms used for file appraisal
IMA: block writes of the security.ima xattr with unsupported algorithms
IMA: remove the dependency on CRYPTO_MD5
ima: Add digest and digest_len params to the functions to measure a buffer
ima: Return int in the functions to measure a buffer
ima: Introduce ima_get_current_hash_algo()
IMA: remove -Wmissing-prototypes warning
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- Add DM infrastructure for IMA-based remote attestion. These changes
are the basis for deploying DM-based storage in a "cloud" that must
validate configurations end-users run to maintain trust. These DM
changes allow supported DM targets' configurations to be measured via
IMA. But the policy and enforcement (of which configurations are
valid) is managed by something outside the kernel (e.g. Keylime).
- Fix DM crypt scalability regression on systems with many cpus due to
percpu_counter spinlock contention in crypt_page_alloc().
- Use in_hardirq() instead of deprecated in_irq() in DM crypt.
- Add event counters to DM writecache to allow users to further assess
how the writecache is performing.
- Various code cleanup in DM writecache's main IO mapping function.
* tag 'for-5.15/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm crypt: use in_hardirq() instead of deprecated in_irq()
dm ima: update dm documentation for ima measurement support
dm ima: update dm target attributes for ima measurements
dm ima: add a warning in dm_init if duplicate ima events are not measured
dm ima: prefix ima event name related to device mapper with dm_
dm ima: add version info to dm related events in ima log
dm ima: prefix dm table hashes in ima log with hash algorithm
dm crypt: Avoid percpu_counter spinlock contention in crypt_page_alloc()
dm: add documentation for IMA measurement support
dm: update target status functions to support IMA measurement
dm ima: measure data on device rename
dm ima: measure data on table clear
dm ima: measure data on device remove
dm ima: measure data on device resume
dm ima: measure data on table load
dm writecache: add event counters
dm writecache: report invalid return from writecache_map helpers
dm writecache: further writecache_map() cleanup
dm writecache: factor out writecache_map_remap_origin()
dm writecache: split up writecache_map() to improve code readability
|
|
Pull block driver updates from Jens Axboe:
"Sitting on top of the core block changes, here are the driver changes
for the 5.15 merge window:
- NVMe updates via Christoph:
- suspend improvements for devices with an HMB (Keith Busch)
- handle double completions more gacefull (Sagi Grimberg)
- cleanup the selects for the nvme core code a bit (Sagi Grimberg)
- don't update queue count when failing to set io queues (Ruozhu Li)
- various nvmet connect fixes (Amit Engel)
- cleanup lightnvm leftovers (Keith Busch, me)
- small cleanups (Colin Ian King, Hou Pu)
- add tracing for the Set Features command (Hou Pu)
- CMB sysfs cleanups (Keith Busch)
- add a mutex_destroy call (Keith Busch)
- remove lightnvm subsystem. It's served its purpose and ultimately
led to zoned nvme support, we no longer need it (Christoph)
- revert floppy O_NDELAY fix (Denis)
- nbd fixes (Hou, Pavel, Baokun)
- nbd locking fixes (Tetsuo)
- nbd device removal fixes (Christoph)
- raid10 rcu warning fix (Xiao)
- raid1 write behind fix (Guoqing)
- rnbd fixes (Gioh, Md Haris)
- misc fixes (Colin)"
* tag 'for-5.15/drivers-2021-08-30' of git://git.kernel.dk/linux-block: (42 commits)
Revert "floppy: reintroduce O_NDELAY fix"
raid1: ensure write behind bio has less than BIO_MAX_VECS sectors
md/raid10: Remove unnecessary rcu_dereference in raid10_handle_discard
nbd: remove nbd->destroy_complete
nbd: only return usable devices from nbd_find_unused
nbd: set nbd->index before releasing nbd_index_mutex
nbd: prevent IDR lookups from finding partially initialized devices
nbd: reset NBD to NULL when restarting in nbd_genl_connect
nbd: add missing locking to the nbd_dev_add error path
nvme: remove the unused NVME_NS_* enum
nvme: remove nvm_ndev from ns
nvme: Have NVME_FABRICS select NVME_CORE instead of transport drivers
block: nbd: add sanity check for first_minor
nvmet: check that host sqsize does not exceed ctrl MQES
nvmet: avoid duplicate qid in connect cmd
nvmet: pass back cntlid on successful completion
nvme-rdma: don't update queue count when failing to set io queues
nvme-tcp: don't update queue count when failing to set io queues
nvme-tcp: pair send_mutex init with destroy
nvme: allow user toggling hmb usage
...
|
|
Pull block updates from Jens Axboe:
"Nothing major in here - lots of good cleanups and tech debt handling,
which is also evident in the diffstats. In particular:
- Add disk sequence numbers (Matteo)
- Discard merge fix (Ming)
- Relax disk zoned reporting restrictions (Niklas)
- Bio error handling zoned leak fix (Pavel)
- Start of proper add_disk() error handling (Luis, Christoph)
- blk crypto fix (Eric)
- Non-standard GPT location support (Dmitry)
- IO priority improvements and cleanups (Damien)o
- blk-throtl improvements (Chunguang)
- diskstats_show() stack reduction (Abd-Alrhman)
- Loop scheduler selection (Bart)
- Switch block layer to use kmap_local_page() (Christoph)
- Remove obsolete disk_name helper (Christoph)
- block_device refcounting improvements (Christoph)
- Ensure gendisk always has a request queue reference (Christoph)
- Misc fixes/cleanups (Shaokun, Oliver, Guoqing)"
* tag 'for-5.15/block-2021-08-30' of git://git.kernel.dk/linux-block: (129 commits)
sg: pass the device name to blk_trace_setup
block, bfq: cleanup the repeated declaration
blk-crypto: fix check for too-large dun_bytes
blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN
blk-zoned: allow zone management send operations without CAP_SYS_ADMIN
block: mark blkdev_fsync static
block: refine the disk_live check in del_gendisk
mmc: sdhci-tegra: Enable MMC_CAP2_ALT_GPT_TEGRA
mmc: block: Support alternative_gpt_sector() operation
partitions/efi: Support non-standard GPT location
block: Add alternative_gpt_sector() operation
bio: fix page leak bio_add_hw_page failure
block: remove CONFIG_DEBUG_BLOCK_EXT_DEVT
block: remove a pointless call to MINOR() in device_add_disk
null_blk: add error handling support for add_disk()
virtio_blk: add error handling support for add_disk()
block: add error handling for device_add_disk / add_disk
block: return errors from disk_alloc_events
block: return errors from blk_integrity_add
block: call blk_register_queue earlier in device_add_disk
...
|
|
The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().
Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20210803141621.780504-16-bigeasy@linutronix.de
|
|
We can't split write behind bio with more than BIO_MAX_VECS sectors,
otherwise the below call trace was triggered because we could allocate
oversized write behind bio later.
[ 8.097936] bvec_alloc+0x90/0xc0
[ 8.098934] bio_alloc_bioset+0x1b3/0x260
[ 8.099959] raid1_make_request+0x9ce/0xc50 [raid1]
[ 8.100988] ? __bio_clone_fast+0xa8/0xe0
[ 8.102008] md_handle_request+0x158/0x1d0 [md_mod]
[ 8.103050] md_submit_bio+0xcd/0x110 [md_mod]
[ 8.104084] submit_bio_noacct+0x139/0x530
[ 8.105127] submit_bio+0x78/0x1d0
[ 8.106163] ext4_io_submit+0x48/0x60 [ext4]
[ 8.107242] ext4_writepages+0x652/0x1170 [ext4]
[ 8.108300] ? do_writepages+0x41/0x100
[ 8.109338] ? __ext4_mark_inode_dirty+0x240/0x240 [ext4]
[ 8.110406] do_writepages+0x41/0x100
[ 8.111450] __filemap_fdatawrite_range+0xc5/0x100
[ 8.112513] file_write_and_wait_range+0x61/0xb0
[ 8.113564] ext4_sync_file+0x73/0x370 [ext4]
[ 8.114607] __x64_sys_fsync+0x33/0x60
[ 8.115635] do_syscall_64+0x33/0x40
[ 8.116670] entry_SYSCALL_64_after_hwframe+0x44/0xae
Thanks for the comment from Christoph.
[1]. https://bugs.archlinux.org/task/70992
Cc: stable@vger.kernel.org # v5.12+
Reported-by: Jens Stutte <jens@chianterastutte.eu>
Tested-by: Jens Stutte <jens@chianterastutte.eu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Signed-off-by: Song Liu <songliubraving@fb.com>
|
|
Move the dax_read_lock/dax_read_unlock pair from the callers into
dax_supported to make it a little easier to use.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/20210826135510.6293-6-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
|
|
There is no point in trying to finding the dax device if the DAX flag is
not set on the queue as none of the users of the device mapper exported
block devices could make use of the DAX capability.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210826135510.6293-4-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
|
|
We are seeing the following warning in raid10_handle_discard.
[ 695.110751] =============================
[ 695.131439] WARNING: suspicious RCU usage
[ 695.151389] 4.18.0-319.el8.x86_64+debug #1 Not tainted
[ 695.174413] -----------------------------
[ 695.192603] drivers/md/raid10.c:1776 suspicious
rcu_dereference_check() usage!
[ 695.225107] other info that might help us debug this:
[ 695.260940] rcu_scheduler_active = 2, debug_locks = 1
[ 695.290157] no locks held by mkfs.xfs/10186.
In the first loop of function raid10_handle_discard. It already
determines which disk need to handle discard request and add the
rdev reference count rdev->nr_pending. So the conf->mirrors will
not change until all bios come back from underlayer disks. It
doesn't need to use rcu_dereference to get rdev.
Cc: stable@vger.kernel.org
Fixes: d30588b2731f ('md/raid10: improve raid10 discard request')
Signed-off-by: Xiao Ni <xni@redhat.com>
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Song Liu <songliubraving@fb.com>
|
|
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
Certain DM targets ('integrity', 'multipath', 'verity') need to update the
way their attributes are recorded in the ima log, so that the attestation
servers can interpret the data correctly and decide if the devices
meet the attestation requirements. For instance, the "mode=%c" attribute
in the 'integrity' target is measured twice, the 'verity' target is
missing the attribute "root_hash_sig_key_desc=%s", and the 'multipath'
target needs to index the attributes properly.
Update 'integrity' target to remove the duplicate measurement of
the attribute "mode=%c". Add "root_hash_sig_key_desc=%s" attribute
for the 'verity' target. Index various attributes in 'multipath'
target. Also, add "nr_priority_groups=%u" attribute to 'multipath'
target to record the number of priority groups.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Suggested-by: Thore Sommer <public@thson.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
The end-users of DM devices/targets may remove and re-create the same
device multiple times. IMA does not measure such duplicate events if the
configuration CONFIG_IMA_DISABLE_HTABLE is set to 'n'.
To avoid confusion, the end-users need some indication on the client
if that configuration option is disabled.
Add a one-time warning during dm_init() if CONFIG_IMA_DISABLE_HTABLE
is set to 'n', to notify the end-users that duplicate events will not
be measured in the ima log. Also cleanup some whitespace in dm_init().
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
The event names for the DM events recorded in the ima log do not contain
any information to indicate the events are part of the DM devices/targets.
Prefix the event names for DM events with "dm_" to indicate that they
are part of device-mapper.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Suggested-by: Thore Sommer <public@thson.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
The DM events present in the ima log contain various attributes in the
key=value format. The attributes' names/values may change in future,
and new attributes may also get added. The attestation server needs
some versioning to determine which attributes are supported and are
expected in the ima log.
Add version information to the DM events present in the ima log to
help attestation servers to correctly process the attributes across
different versions.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
The active/inactive table hashes measured in the ima log do not contain
the information about hash algorithm. This information is useful for the
attestation servers to recreate the hashes and compare them with the ones
present in the ima log to verify the table contents.
Prefix the table hashes in various DM events in ima log with the hash
algorithm used to compute those hashes.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
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 <dj@corelight.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Arne Welzel <arne.welzel@corelight.com>
Fixes: 5059353df86e ("dm crypt: limit the number of allocated pages")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
Use bvec_virt instead of open coding it. Note that the existing code is
fine despite ignoring bv_offset as the bio is known to contain exactly
one page from the page allocator per bio_vec.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20210804095634.460779-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Use bvec_virt instead of open coding it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210804095634.460779-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Use bvec_virt instead of open coding it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210804095634.460779-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
__ebs_rw_bvec use page_address on the submitted bios data, and thus
can't deal with highmem. Disable the target on highmem configs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210804095634.460779-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Just check inode_unhashed on the whole device bdev inode instead,
and provide a helper to check for that information.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210809064028.1198327-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Let the callers call del_gendisk so that we can check if add_disk
has been called properly for the cached device case instead of relying
on the block layer internal GENHD_FL_UP flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20210809064028.1198327-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Except for the IDA none of the allocations in bcache_device_init is
unwound on error, fix that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20210809064028.1198327-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Move them (PAGE_SECTORS_SHIFT, PAGE_SECTORS and SECTOR_MASK) to the
generic header file to remove redundancy.
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Link: https://lore.kernel.org/r/20210721025315.1729118-1-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
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 <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
A given block device is identified by it's name and UUID. However, both
these parameters can be renamed. For an external attestation service to
correctly attest a given device, it needs to keep track of these rename
events.
Update the device data with the new values for IMA measurements. Measure
both old and new device name/UUID parameters in the same IMA measurement
event, so that the old and the new values can be connected later.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
For a given block device, an inactive table slot contains the parameters
to configure the device with. The inactive table can be cleared
multiple times, accidentally or maliciously, which may impact the
functionality of the device, and compromise the system. Therefore it is
important to measure and log the event when a table is cleared.
Measure device parameters, and table hashes when the inactive table slot
is cleared.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
Presence of an active block-device, configured with expected parameters,
is important for an external attestation service to determine if a system
meets the attestation requirements. Therefore it is important for DM to
measure the device remove events.
Measure device parameters and table hashes when the device is removed,
using either remove or remove_all.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
A given block device can load a table multiple times, with different
input parameters, before eventually resuming it. Further, a device may
be suspended and then resumed. The device may never resume after a
table-load. Because of the above valid scenarios for a given device,
it is important to measure and log the device resume event using IMA.
Also, if the table is large, measuring it in clear-text each time the
device changes state, will unnecessarily increase the size of IMA log.
Since the table clear-text is already measured during table-load event,
measuring the hash during resume should be sufficient to validate the
table contents.
Measure the device parameters, and hash of the active table, when the
device is resumed.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
|
|
DM configures a block device with various target specific attributes
passed to it as a table. DM loads the table, and calls each target’s
respective constructors with the attributes as input parameters.
Some of these attributes are critical to ensure the device meets
certain security bar. Thus, IMA should measure these attributes, to
ensure they are not tampered with, during the lifetime of the device.
So that the external services can have high confidence in the
configuration of the block-devices on a given system.
Some devices may have large tables. And a given device may change its
state (table-load, suspend, resume, rename, remove, table-clear etc.)
many times. Measuring these attributes each time when the device
changes its state will significantly increase the size of the IMA logs.
Further, once configured, these attributes are not expected to change
unless a new table is loaded, or a device is removed and recreated.
Therefore the clear-text of the attributes should only be measured
during table load, and the hash of the active/inactive table should be
measured for the remaining device state changes.
Export IMA function ima_measure_critical_data() to allow measurement
of DM device parameters, as well as target specific attributes, during
table load. Compute the hash of the inactive table and store it for
measurements during future state change. If a load is called multiple
times, update the inactive table hash with the hash of the latest
populated table. So that the correct inactive table hash is measured
when the device transitions to different states like resume, remove,
rename, etc.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com> # leak fix
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Add 10 counters for various events (hit, miss, etc) and export them in
the status line (accessed from userspace with "dmsetup status"). Also
add a message "clear_stats" that resets these counters.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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