Linux allows executing the SG_IO ioctl on a partition or LVM volume, and
will pass the command to the underlying block device. This is
well-known, but it is also a large security problem when (via Unix
permissions, ACLs, SELinux or a combination thereof) a program or user
needs to be granted access only to part of the disk.
This patch lets partitions forward a small set of harmless ioctls;
others are logged with printk so that we can see which ioctls are
actually sent. In my tests only CDROM_GET_CAPABILITY actually occurred.
Of course it was being sent to a (partition on a) hard disk, so it would
have failed with ENOTTY and the patch isn't changing anything in
practice. Still, I'm treating it specially to avoid spamming the logs.
In principle, this restriction should include programs running with
CAP_SYS_RAWIO. If for example I let a program access /dev/sda2 and
/dev/sdb, it still should not be able to read/write outside the
boundaries of /dev/sda2 independent of the capabilities. However, for
now programs with CAP_SYS_RAWIO will still be allowed to send the
ioctls. Their actions will still be logged.
This patch does not affect the non-libata IDE driver. That driver
however already tests for bd != bd->bd_contains before issuing some
ioctl; it could be restricted further to forbid these ioctls even for
programs running with CAP_SYS_ADMIN/CAP_SYS_RAWIO.
Cc: linux-scsi@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>
Cc: James Bottomley <JBottomley@parallels.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[ Make it also print the command name when warning - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce an ioctl which permits applications to query whether a block
device is rotational.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Stacking driver queue limits are typically bounded exclusively by the
capabilities of the low level devices, not by the stacking driver
itself.
This patch introduces blk_set_stacking_limits() which has more liberal
metrics than the default queue limits function. This allows us to
inherit topology parameters from bottom devices without manually
tweaking the default limits in each driver prior to calling the stacking
function.
Since there is now a clear distinction between stacking and low-level
devices, blk_set_default_limits() has been modified to carry the more
conservative values that we used to manually set in
blk_queue_make_request().
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
* 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
cgroup: fix to allow mounting a hierarchy by name
cgroup: move assignement out of condition in cgroup_attach_proc()
cgroup: Remove task_lock() from cgroup_post_fork()
cgroup: add sparse annotation to cgroup_iter_start() and cgroup_iter_end()
cgroup: mark cgroup_rmdir_waitq and cgroup_attach_proc() as static
cgroup: only need to check oldcgrp==newgrp once
cgroup: remove redundant get/put of task struct
cgroup: remove redundant get/put of old css_set from migrate
cgroup: Remove unnecessary task_lock before fetching css_set on migration
cgroup: Drop task_lock(parent) on cgroup_fork()
cgroups: remove redundant get/put of css_set from css_set_check_fetched()
resource cgroups: remove bogus cast
cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task()
cgroup, cpuset: don't use ss->pre_attach()
cgroup: don't use subsys->can_attach_task() or ->attach_task()
cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach()
cgroup: improve old cgroup handling in cgroup_attach_proc()
cgroup: always lock threadgroup during migration
threadgroup: extend threadgroup_lock() to cover exit and exec
threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem
...
Fix up conflict in kernel/cgroup.c due to commit e0197aae59: "cgroups:
fix a css_set not found bug in cgroup_attach_proc" that already
mentioned that the bug is fixed (differently) in Tejun's cgroup
patchset. This one, in other words.
* 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (165 commits)
reiserfs: Properly display mount options in /proc/mounts
vfs: prevent remount read-only if pending removes
vfs: count unlinked inodes
vfs: protect remounting superblock read-only
vfs: keep list of mounts for each superblock
vfs: switch ->show_options() to struct dentry *
vfs: switch ->show_path() to struct dentry *
vfs: switch ->show_devname() to struct dentry *
vfs: switch ->show_stats to struct dentry *
switch security_path_chmod() to struct path *
vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb
vfs: trim includes a bit
switch mnt_namespace ->root to struct mount
vfs: take /proc/*/mounts and friends to fs/proc_namespace.c
vfs: opencode mntget() mnt_set_mountpoint()
vfs: spread struct mount - remaining argument of next_mnt()
vfs: move fsnotify junk to struct mount
vfs: move mnt_devname
vfs: move mnt_list to struct mount
vfs: switch pnode.h macros to struct mount *
...
We're doing some odd things there, which already messes up various users
(see the net/socket.c code that this removes), and it was going to add
yet more crud to the block layer because of the incorrect error code
translation.
ENOIOCTLCMD is not an error return that should be returned to user mode
from the "ioctl()" system call, but it should *not* be translated as
EINVAL ("Invalid argument"). It should be translated as ENOTTY
("Inappropriate ioctl for device").
That EINVAL confusion has apparently so permeated some code that the
block layer actually checks for it, which is sad. We continue to do so
for now, but add a big comment about how wrong that is, and we should
remove it entirely eventually. In the meantime, this tries to keep the
changes localized to just the EINVAL -> ENOTTY fix, and removing code
that makes it harder to do the right thing.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
both callers of device_get_devnode() are only interested in lower 16bits
and nobody tries to return anything wider than 16bit anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Move invalidate_bdev, block_sync_page into fs/block_dev.c. Export
kill_bdev as well, so brd doesn't have to open code it. Reduce
buffer_head.h requirement accordingly.
Removed a rather large comment from invalidate_bdev, as it looked a bit
obsolete to bother moving. The small comment replacing it says enough.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 5e081591 "block: warn if tag is greater than real_max_depth"
cleaned up blk_queue_end_tag() to warn when the tag is truly invalid
(greater than real_max_depth). However, it changed behavior in the tag <
max_depth case to not end the request. Leading to triggering of
BUG_ON(blk_queued_rq(rq)) in the request completion path:
http://marc.info/?l=linux-kernel&m=132204370518629&w=2
In order to allow blk_queue_resize_tags() to shrink the tag space
blk_queue_end_tag() must always complete tags with a value less than
real_max_depth regardless of the current max_depth. The comment about
"handling the shrink case" seems to be what prompted changes in this
space, so remove it and BUG on all invalid tags (made even simpler by
Matthew's suggestion to use an unsigned compare).
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Tao Ma <boyu.mt@taobao.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Reported-by: Meelis Roos <mroos@ut.ee>
Reported-by: Ed Nadolski <edmund.nadolski@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
6e736be7 "block: make ioc get/put interface more conventional and fix
race on alloction" added WARN_ON_ONCE() in exit_io_context() which
triggers if !PF_EXITING. All tasks hitting exit_io_context() from
task exit should have PF_EXITING set but task struct tearing down
after fork failure calls into the function without PF_EXITING,
triggering the condition.
WARNING: at block/blk-ioc.c:234 exit_io_context+0x40/0x92()
Pid: 17090, comm: trinity Not tainted 3.2.0-rc6-next-20111222-sasha-dirty #77
Call Trace:
[<ffffffff810b69a3>] warn_slowpath_common+0x8f/0xb2
[<ffffffff810b6a77>] warn_slowpath_null+0x18/0x1a
[<ffffffff8181a7a2>] exit_io_context+0x40/0x92
[<ffffffff810b58c9>] copy_process+0x126f/0x1453
[<ffffffff810b5c1b>] do_fork+0x120/0x3e9
[<ffffffff8106242f>] sys_clone+0x26/0x28
[<ffffffff82425803>] stub_clone+0x13/0x20
---[ end trace a2e4eb670b375238 ]---
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
While fixing io_context creation / task exit race condition,
6e736be7f2 "block: make ioc get/put interface more conventional and
fix race on alloction" also prevented an exiting (%PF_EXITING) task
from creating its own io_context. This is incorrect as exit path may
issue IOs, e.g. from exit_files(), and if those IOs are the first ones
issued by the task, io_context needs to be created to process the IOs.
Combined with the existing problem of io_context / io_cq creation
failure having the possibility of stalling IO, this problem results in
deterministic full IO lockup with certain workloads.
Fix it by allowing io_context creation regardless of %PF_EXITING for
%current.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With the ioc changed, ioc_cgroup_changed() can be used by modular
code. So ensure that it is exported.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All requests of a queue could be merged to other requests of other queue.
Such queue will not have request in it, but it's in service tree. This
will cause kernel oops.
I encounter a BUG_ON() in cfq_dispatch_request() with next patch, but the
issue should exist without the patch.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In my workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1,
a+3,.... When the requests are flushed to queue, a and a+1 are merged
to (a, a+1), a+2 and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3)
aren't merged.
With recursive merge below, the workload throughput gets improved 20%
and context switch drops 60%.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All requests of a queue could be merged to other requests of other queue.
Such queue will not have request in it, but it's in service tree. This
will cause kernel oops.
I encounter a BUG_ON() in cfq_dispatch_request() with next patch, but the
issue should exist without the patch.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
While probing, fd sets up queue, probes hardware and tears down the
queue if probing fails. In the process, blk_drain_queue() kicks the
queue which failed to finish initialization and fd is unhappy about
that.
floppy0: no floppy controllers found
------------[ cut here ]------------
WARNING: at drivers/block/floppy.c:2929 do_fd_request+0xbf/0xd0()
Hardware name: To Be Filled By O.E.M.
VFS: do_fd_request called on non-open device
Modules linked in:
Pid: 1, comm: swapper Not tainted 3.2.0-rc4-00077-g5983fe2 #2
Call Trace:
[<ffffffff81039a6a>] warn_slowpath_common+0x7a/0xb0
[<ffffffff81039b41>] warn_slowpath_fmt+0x41/0x50
[<ffffffff813d657f>] do_fd_request+0xbf/0xd0
[<ffffffff81322b95>] blk_drain_queue+0x65/0x80
[<ffffffff81322c93>] blk_cleanup_queue+0xe3/0x1a0
[<ffffffff818a809d>] floppy_init+0xdeb/0xe28
[<ffffffff818a72b2>] ? daring+0x6b/0x6b
[<ffffffff810002af>] do_one_initcall+0x3f/0x170
[<ffffffff81884b34>] kernel_init+0x9d/0x11e
[<ffffffff810317c2>] ? schedule_tail+0x22/0xa0
[<ffffffff815dbb14>] kernel_thread_helper+0x4/0x10
[<ffffffff81884a97>] ? start_kernel+0x2be/0x2be
[<ffffffff815dbb10>] ? gs_change+0xb/0xb
Avoid it by making blk_drain_queue() kick queue iff dispatch queue has
something on it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ralf Hildebrandt <Ralf.Hildebrandt@charite.de>
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Tested-by: Sergei Trofimovich <slyich@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now block layer knows everything necessary to create and associate
icq's with requests. Move ioc_create_icq() to blk-ioc.c and update
get_request() such that, if elevator_type->icq_size is set, requests
are automatically associated with their matching icq's before
elv_set_request(). io_context reference is also managed by block core
on request alloc/free.
* Only ioprio/cgroup changed handling remains from cfq_get_cic().
Collapsed into cfq_set_request().
* This removes queue kicking on icq allocation failure (for now). As
icq allocation failure is rare and the only effect of queue kicking
achieved was possibily accelerating queue processing, this change
shouldn't be noticeable.
There is a larger underlying problem. Unlike request allocation,
icq allocation is not guaranteed to succeed eventually after
retries. The number of icq is unbound and thus mempool can't be the
solution either. This effectively adds allocation dependency on
memory free path and thus possibility of deadlock.
This usually wouldn't happen because icq allocation is not a hot
path and, even when the condition triggers, it's highly unlikely
that none of the writeback workers already has icq.
However, this is still possible especially if elevator is being
switched under high memory pressure, so we better get it fixed.
Probably the only solution is just bypassing elevator and appending
to dispatch queue on any elevator allocation failure.
* Comment added to explain how icq's are managed and synchronized.
This completes cleanup of io_context interface.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add elevator_ops->elevator_init_icq_fn() and restructure
cfq_create_cic() and rename it to ioc_create_icq().
The new function expects its caller to pass in io_context, uses
elevator_type->icq_cache, handles generic init, calls the new elevator
operation for elevator specific initialization, and returns pointer to
created or looked up icq. This leaves cfq_icq_pool variable without
any user. Removed.
This prepares for io_context interface cleanup and doesn't introduce
any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to
blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced
with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc
and q, and freeing automatically handled by blk-ioc. The elevator
operation only need to perform exit operation specific to the elevator
- in cfq's case, exiting the cfqq's.
Also, clearing of io_cq's on q detach is moved to block core and
automatically performed on elevator switch and q release.
Because the q io_cq points to might be freed before RCU callback for
the io_cq runs, blk-ioc code should remember to which cache the io_cq
needs to be freed when the io_cq is released. New field
io_cq->__rcu_icq_cache is added for this purpose. As both the new
field and rcu_head are used only after io_cq is released and the
q/ioc_node fields aren't, they are put into unions.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Paolo Bonzini
Martin K. Petersen
Linus Torvalds
Al Viro
Dan Williams
Tejun Heo
majianpeng
Jens Axboe
Shaohua Li