__hash_remove() removes hash_cell with _hash_lock locked, so acquiring
_hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
have not been removed and hc->md must still be md.
__hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
as NULL. So in dm_copy_name_and_uuid(), after acquiring
dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
hc must still be alive and hc->md must still be md.
Remove the unnecessary hc->md != md checks when using dm_get_mdptr()
with _hash_lock or dm_hash_cells_mutex acquired.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Also update dm_early_create() to take _hash_lock when calling both
__get_name_cell and __hash_remove -- given dm_early_create()'s early
boot usecase this locking isn't about correctness but it allows
lockdep_assert_held() to be added to __hash_remove.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has
deprecated its use.
Suggested-by: John Wiele <jwiele@redhat.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Device mapper sends an uevent when the device is suspended, using the
function set_capacity_and_notify. However, this causes a race condition
with udev.
Udev skips scanning dm devices that are suspended. If we send an uevent
while we are suspended, udev will be racing with device mapper resume
code. If the device mapper resume code wins the race, udev will process
the uevent after the device is resumed and it will properly scan the
device.
However, if udev wins the race, it will receive the uevent, find out that
the dm device is suspended and skip scanning the device. This causes bugs
such as systemd unmounting the device - see
https://bugzilla.redhat.com/show_bug.cgi?id=2158628
This commit fixes this race.
We replace the function set_capacity_and_notify with set_capacity, so that
the uevent is not sent at this point. In do_resume, we detect if the
capacity has changed and we pass a boolean variable need_resize_uevent to
dm_kobject_uevent. dm_kobject_uevent adds "RESIZE=1" to the uevent if
need_resize_uevent is set.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Tested-by: Peter Rajnoha <prajnoha@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
The expression 'indata[3] > ULONG_MAX' always evaluates to false since
indata[] is declared as an array of *unsigned long* elements and #define
ULONG_MAX represents the max value of that exact type...
Note that gcc seems to be able to detect the dead code here and eliminate
this check anyway...
Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Change the ioctl codes from DM_DEV_ARM_POLL to DM_DEV_ARM_POLL_CMD and
from DM_GET_TARGET_VERSION to DM_GET_TARGET_VERSION_CMD.
Note that the "cmd" field of "struct _ioctls" is never used, thus this
commit doesn't fix any bug, it just makes the code consistent.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
No need to modify info->vers if we overwrite it immediately.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
__list_versions will first estimate the required space using the
"dm_target_iterate(list_version_get_needed, &needed)" call and then will
fill the space using the "dm_target_iterate(list_version_get_info,
&iter_info)" call. Each of these calls locks the targets using the
"down_read(&_lock)" and "up_read(&_lock)" calls, however between the first
and second "dm_target_iterate" there is no lock held and the target
modules can be loaded at this point, so the second "dm_target_iterate"
call may need more space than what was the first "dm_target_iterate"
returned.
The code tries to handle this overflow (see the beginning of
list_version_get_info), however this handling is incorrect.
The code sets "param->data_size = param->data_start + needed" and
"iter_info.end = (char *)vers+len" - "needed" is the size returned by the
first dm_target_iterate call; "len" is the size of the buffer allocated by
userspace.
"len" may be greater than "needed"; in this case, the code will write up
to "len" bytes into the buffer, however param->data_size is set to
"needed", so it may write data past the param->data_size value. The ioctl
interface copies only up to param->data_size into userspace, thus part of
the result will be truncated.
Fix this bug by setting "iter_info.end = (char *)vers + needed;" - this
guarantees that the second "dm_target_iterate" call will write only up to
the "needed" buffer and it will exit with "DM_BUFFER_FULL_FLAG" if it
overflows the "needed" space - in this case, userspace will allocate a
larger buffer and retry.
Note that there is also a bug in list_version_get_needed - we need to add
"strlen(tt->name) + 1" to the needed size, not "strlen(tt->name)".
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Change DMWARN to DMERR in cases when there is an unrecoverable error.
Change DMWARN to DMCRIT when handling of a case is unimplemented.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
More efficient and readable to just access table->num_targets directly.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This will help triage bugs when userspace is passing invalid ioctl
structure to the kernel.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
[snitzer: log errors using DMERR instead of DMWARN]
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
It appears like cmd could be a Spectre v1 gadget as it's supplied by a
user and used as an array index. Prevent the contents of kernel memory
from being leaked to userspace via speculative execution by using
array_index_nospec.
Signed-off-by: Jordy Zomer <jordy@pwning.systems>
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>
Move setting md->type from both callers into dm_setup_md_queue.
This ensures that md->type is only set to a valid value after the queue
has been fully setup, something we'll rely on future changes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If we set non-empty param->name or param->uuid on the DM_LIST_DEVICES_CMD
ioctl, the set values are considered filter prefixes. The ioctl will only
return entries with matching name or uuid prefix.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When LVM needs to find a device with a particular UUID it needs to ask for
UUID for each device. This patch returns UUID directly in the list of
devices, so that LVM doesn't have to query all the devices with an ioctl.
The UUID is returned if the flag DM_UUID_FLAG is set in the parameters.
Returning UUID is done in backward-compatible way. There's one unused
32-bit word value after the event number. This patch sets the bit
DM_NAME_LIST_FLAG_HAS_UUID if UUID is present and
DM_NAME_LIST_FLAG_DOESNT_HAVE_UUID if it isn't (if none of these bits is
set, then we have an old kernel that doesn't support returning UUIDs). The
UUID is stored after this word. The 'next' value is updated to point after
the UUID, so that old version of libdevmapper will skip the UUID without
attempting to interpret it.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
For high numbers of DM devices the 64-entry hash table has non-trivial
overhead. Fix this by replacing the hash table with a red-black tree.
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
If there are not any dm devices, we need to zero the "dev" argument in
the first structure dm_name_list. However, this can cause out of
bounds write, because the "needed" variable is zero and len may be
less than eight.
Fix this bug by reporting DM_BUFFER_FULL_FLAG if the result buffer is
too small to hold the "nl->dev" value.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.
Fixes: 2ca4c92f58 ("dm ioctl: prevent empty message")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
bio-based code so that it follows patterns established by
request-based code.
- Request-based DM core improvement to eliminate unnecessary call to
blk_mq_queue_stopped().
- Add "panic_on_corruption" error handling mode to DM verity target.
- DM bufio fix to to perform buffer cleanup from a workqueue rather
than wait for IO in reclaim context from shrinker.
- DM crypt improvement to optionally avoid async processing via
workqueues for reads and/or writes -- via "no_read_workqueue" and
"no_write_workqueue" features. This more direct IO processing
improves latency and throughput with faster storage. Avoiding
workqueue IO submission for writes (DM_CRYPT_NO_WRITE_WORKQUEUE) is
a requirement for adding zoned block device support to DM crypt.
- Add zoned block device support to DM crypt. Makes use of
DM_CRYPT_NO_WRITE_WORKQUEUE and a new optional feature
(DM_CRYPT_WRITE_INLINE) that allows write completion to wait for
encryption to complete. This allows write ordering to be preserved,
which is needed for zoned block devices.
- Fix DM ebs target's check for REQ_OP_FLUSH.
- Fix DM core's report zones support to not report more zones than
were requested.
- A few small compiler warning fixes.
- DM dust improvements to return output directly to the user rather
than require they scrape the system log for output.
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Merge tag 'for-5.9/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- DM multipath locking fixes around m->flags tests and improvements to
bio-based code so that it follows patterns established by
request-based code.
- Request-based DM core improvement to eliminate unnecessary call to
blk_mq_queue_stopped().
- Add "panic_on_corruption" error handling mode to DM verity target.
- DM bufio fix to to perform buffer cleanup from a workqueue rather
than wait for IO in reclaim context from shrinker.
- DM crypt improvement to optionally avoid async processing via
workqueues for reads and/or writes -- via "no_read_workqueue" and
"no_write_workqueue" features. This more direct IO processing
improves latency and throughput with faster storage. Avoiding
workqueue IO submission for writes (DM_CRYPT_NO_WRITE_WORKQUEUE) is a
requirement for adding zoned block device support to DM crypt.
- Add zoned block device support to DM crypt. Makes use of
DM_CRYPT_NO_WRITE_WORKQUEUE and a new optional feature
(DM_CRYPT_WRITE_INLINE) that allows write completion to wait for
encryption to complete. This allows write ordering to be preserved,
which is needed for zoned block devices.
- Fix DM ebs target's check for REQ_OP_FLUSH.
- Fix DM core's report zones support to not report more zones than were
requested.
- A few small compiler warning fixes.
- DM dust improvements to return output directly to the user rather
than require they scrape the system log for output.
* tag 'for-5.9/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm: don't call report zones for more than the user requested
dm ebs: Fix incorrect checking for REQ_OP_FLUSH
dm init: Set file local variable static
dm ioctl: Fix compilation warning
dm raid: Remove empty if statement
dm verity: Fix compilation warning
dm crypt: Enable zoned block device support
dm crypt: add flags to optionally bypass kcryptd workqueues
dm bufio: do buffer cleanup from a workqueue
dm rq: don't call blk_mq_queue_stopped() in dm_stop_queue()
dm dust: add interface to list all badblocks
dm dust: report some message results directly back to user
dm verity: add "panic_on_corruption" error handling mode
dm mpath: use double checked locking in fast path
dm mpath: rename current_pgpath to pgpath in multipath_prepare_ioctl
dm mpath: rework __map_bio()
dm mpath: factor out multipath_queue_bio
dm mpath: push locking down to must_push_back_rq()
dm mpath: take m->lock spinlock when testing QUEUE_IF_NO_PATH
dm mpath: changes from initial m->flags locking audit
In retrieve_status(), when copying the target type name in the
target_type string field of struct dm_target_spec, copy at most
DM_MAX_TYPE_NAME - 1 character to avoid the compilation warning:
warning: ‘__builtin_strncpy’ specified bound 16 equals destination
size [-Wstringop-truncation]
when compiling with W-1.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.
In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:
git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
xargs perl -pi -e \
's/\buninitialized_var\(([^\)]+)\)/\1/g;
s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'
drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.
No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.
[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: Kees Cook <keescook@chromium.org>
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct dm_target_deps {
...
__u64 dev[0]; /* out */
};
Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit introduces a new ioctl DM_GET_TARGET_VERSION. It will load a
target that is specified in the "name" entry in the parameter structure
and return its version.
This functionality is intended to be used by cryptsetup, so that it can
query kernel capabilities before activating the device.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Currently, if we pass too high sector number to dm_table_find_target, it
returns zeroed dm_target structure and callers test if the structure is
zeroed with the macro dm_target_is_valid.
However, returning NULL is common practice to indicate errors.
This patch refactors the dm code, so that dm_table_find_target returns
NULL and its callers test the returned value for NULL. The macro
dm_target_is_valid is deleted. In alloc_targets, we no longer allocate an
extra zeroed target.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The dm_early_create() function (which deals with "dm-mod.create=" kernel
command line option) calls dm_hash_insert() who gets an extra reference
to the md object.
In case of failure, this reference wasn't being released, causing
dm_destroy() to hang, thus hanging the whole boot process.
Fix this by calling __hash_remove() in the error path.
Fixes: 6bbc923dfc ("dm: add support to directly boot to a mapped device")
Cc: stable@vger.kernel.org
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Add a "create" module parameter, which allows device-mapper targets to
be configured at boot time. This enables early use of DM targets in the
boot process (as the root device or otherwise) without the need of an
initramfs.
The syntax used in the boot param is based on the concise format from
the dmsetup tool to follow the rule of least surprise:
dmsetup table --concise /dev/mapper/lroot
Which is:
dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+]
Where,
<name> ::= The device name.
<uuid> ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | ""
<minor> ::= The device minor number | ""
<flags> ::= "ro" | "rw"
<table> ::= <start_sector> <num_sectors> <target_type> <target_args>
<target_type> ::= "verity" | "linear" | ...
For example, the following could be added in the boot parameters:
dm-mod.create="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0
Only the targets that were tested are allowed and the ones that don't
change any block device when the device is create as read-only. For
example, mirror and cache targets are not allowed. The rationale behind
this is that if the user makes a mistake, choosing the wrong device to
be the mirror or the cache can corrupt data.
The only targets initially allowed are:
* crypt
* delay
* linear
* snapshot-origin
* striped
* verity
Co-developed-by: Will Drewry <wad@chromium.org>
Co-developed-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
In copy_params(), the struct 'dm_ioctl' is first copied from the user
space buffer 'user' to 'param_kernel' and the field 'data_size' is
checked against 'minimum_data_size' (size of 'struct dm_ioctl' payload
up to its 'data' member). If the check fails, an error code EINVAL will be
returned. Otherwise, param_kernel->data_size is used to do a second copy,
which copies from the same user-space buffer to 'dmi'. After the second
copy, only 'dmi->data_size' is checked against 'param_kernel->data_size'.
Given that the buffer 'user' resides in the user space, a malicious
user-space process can race to change the content in the buffer between
the two copies. This way, the attacker can inject inconsistent data
into 'dmi' (versus previously validated 'param_kernel').
Fix redundant copying of 'minimum_data_size' from user-space buffer by
using the first copy stored in 'param_kernel'. Also remove the
'data_size' check after the second copy because it is now unnecessary.
Cc: stable@vger.kernel.org
Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Could be useful for a target to return stats or other information.
If a target does DMEMIT() anything to @result from its .message method
then it must return 1 to the caller.
Signed-off-By: Mike Snitzer <snitzer@redhat.com>
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done
with de-mangling cleanups yet to come.
NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.
The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The size of struct dm_name_list is different on 32-bit and 64-bit
kernels (so "(nl + 1)" differs between 32-bit and 64-bit kernels).
This mismatch caused some harmless difference in padding when using 32-bit
or 64-bit kernel. Commit 23d70c5e52 ("dm ioctl: report event number in
DM_LIST_DEVICES") added reporting event number in the output of
DM_LIST_DEVICES_CMD. This difference in padding makes it impossible for
userspace to determine the location of the event number (the location
would be different when running on 32-bit and 64-bit kernels).
Fix the padding by using offsetof(struct dm_name_list, name) instead of
sizeof(struct dm_name_list) to determine the location of entries.
Also, the ioctl version number is incremented to 37 so that userspace
can use the version number to determine that the event number is present
and correctly located.
In addition, a global event is now raised when a DM device is created,
removed, renamed or when table is swapped, so that the user can monitor
for device changes.
Reported-by: Eugene Syromiatnikov <esyr@redhat.com>
Fixes: 23d70c5e52 ("dm ioctl: report event number in DM_LIST_DEVICES")
Cc: stable@vger.kernel.org # 4.13
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Constify the lookup table for device-mapper ioctls so that it is placed
in .rodata.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Report the event numbers for all the devices, so that the user doesn't
have to ask them one by one. The event number is reported after the
name field in the dm_name_list structure.
The location of the next record is specified in the dm_name_list->next
field, that means that we can put the new data after the end of name and
it is backward compatible with the old code. The old code just skips
the event number without interpreting it.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This ioctl will record the current global event number in the structure
dm_file, so that next select or poll call will wait until new events
arrived since this ioctl.
The DM_DEV_ARM_POLL ioctl has the same effect as closing and reopening
the handle.
Using the DM_DEV_ARM_POLL ioctl is optional - if the userspace is OK
with closing and reopening the /dev/mapper/control handle after select
or poll, there is no need to re-arm via ioctl.
Usage:
1. open the /dev/mapper/control device
2. send the DM_DEV_ARM_POLL ioctl
3. scan the event numbers of all devices we are interested in and process
them
4. call select, poll or epoll on the handle (it waits until some new event
happens since the DM_DEV_ARM_POLL ioctl)
5. go to step 2
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Hou Tao