btrfs, debugfs, reiserfs and tracefs call save_mount_options() and reiserfs
calls replace_mount_options(), but they then implement their own
->show_options() methods and don't touch s_options, rendering the saved
options unnecessary. I'm trying to eliminate s_options to make it easier
to implement a context-based mount where the mount options can be passed
individually over a file descriptor.
Remove the calls to save/replace_mount_options() call in these cases.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Chris Mason <clm@fb.com>
cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cc: Steven Rostedt <rostedt@goodmis.org>
cc: linux-btrfs@vger.kernel.org
cc: reiserfs-devel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently immutable and noatime flags on quota files are set by quota
code which requires us to copy inode->i_flags to our on disk version of
quota flags in GETFLAGS ioctl and when writing stat item. Move to
setting / clearing these on-disk flags directly to save that copying.
Signed-off-by: Jan Kara <jack@suse.cz>
dquot_writeback_dquots() expects s_umount semaphore to be held to
protect it from other concurrent quota operations. reiserfs_sync_fs()
can call dquot_writeback_dquots() without holding s_umount semaphore
when called from flush_old_commits().
Fix the problem by grabbing s_umount in flush_old_commits(). However we
have to be careful and use only trylock since reiserfs_cancel_old_sync()
can be waiting for flush_old_commits() to complete while holding
s_umount semaphore. Possible postponing of sync work is not a big deal
though as that is only an opportunistic flush.
Fixes: 9d1ccbe70e
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently canceling of delayed work that flushes old data using
cancel_old_flush() does not prevent work from being requeued. Thus
in theory new work can be queued after cancel_old_flush() from
reiserfs_freeze() has run. This will become larger problem once
flush_old_commits() can requeue the work itself.
Fix the problem by recording in sbi->work_queue that flushing work is
canceled and should not be requeued.
Signed-off-by: Jan Kara <jack@suse.cz>
See i_size_read() comments in include/linux/fs.h
Link: http://lkml.kernel.org/r/20170123174701.30394-1-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull more vfs updates from Al Viro:
">rename2() work from Miklos + current_time() from Deepa"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Replace current_fs_time() with current_time()
fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
fs: Replace CURRENT_TIME with current_time() for inode timestamps
fs: proc: Delete inode time initializations in proc_alloc_inode()
vfs: Add current_time() api
vfs: add note about i_op->rename changes to porting
fs: rename "rename2" i_op to "rename"
vfs: remove unused i_op->rename
fs: make remaining filesystems use .rename2
libfs: support RENAME_NOREPLACE in simple_rename()
fs: support RENAME_NOREPLACE for local filesystems
ncpfs: fix unused variable warning
CURRENT_TIME_SEC is not y2038 safe. current_time() will
be transitioned to use 64 bit time along with vfs in a
separate patch.
There is no plan to transistion CURRENT_TIME_SEC to use
y2038 safe time interfaces.
current_time() will also be extended to use superblock
range checking parameters when range checking is introduced.
This works because alloc_super() fills in the the s_time_gran
in super block to NSEC_PER_SEC.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull core block updates from Jens Axboe:
- the big change is the cleanup from Mike Christie, cleaning up our
uses of command types and modified flags. This is what will throw
some merge conflicts
- regression fix for the above for btrfs, from Vincent
- following up to the above, better packing of struct request from
Christoph
- a 2038 fix for blktrace from Arnd
- a few trivial/spelling fixes from Bart Van Assche
- a front merge check fix from Damien, which could cause issues on
SMR drives
- Atari partition fix from Gabriel
- convert cfq to highres timers, since jiffies isn't granular enough
for some devices these days. From Jan and Jeff
- CFQ priority boost fix idle classes, from me
- cleanup series from Ming, improving our bio/bvec iteration
- a direct issue fix for blk-mq from Omar
- fix for plug merging not involving the IO scheduler, like we do for
other types of merges. From Tahsin
- expose DAX type internally and through sysfs. From Toshi and Yigal
* 'for-4.8/core' of git://git.kernel.dk/linux-block: (76 commits)
block: Fix front merge check
block: do not merge requests without consulting with io scheduler
block: Fix spelling in a source code comment
block: expose QUEUE_FLAG_DAX in sysfs
block: add QUEUE_FLAG_DAX for devices to advertise their DAX support
Btrfs: fix comparison in __btrfs_map_block()
block: atari: Return early for unsupported sector size
Doc: block: Fix a typo in queue-sysfs.txt
cfq-iosched: Charge at least 1 jiffie instead of 1 ns
cfq-iosched: Fix regression in bonnie++ rewrite performance
cfq-iosched: Convert slice_resid from u64 to s64
block: Convert fifo_time from ulong to u64
blktrace: avoid using timespec
block/blk-cgroup.c: Declare local symbols static
block/bio-integrity.c: Add #include "blk.h"
block/partition-generic.c: Remove a set-but-not-used variable
block: bio: kill BIO_MAX_SIZE
cfq-iosched: temporarily boost queue priority for idle classes
block: drbd: avoid to use BIO_MAX_SIZE
block: bio: remove BIO_MAX_SECTORS
...
This has ll_rw_block users pass in the operation and flags separately,
so ll_rw_block can setup the bio op and bi_rw flags on the bio that
is submitted.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Check out-of-memory failure of the kstrdup option. Note that the argument
"arg" may be NULL (in that case kstrup returns NULL), so out of memory
condition happened if arg was non-NULL and kstrdup returned NULL.
The patch also changes the call to replace_mount_options - if we didn't
pass any filesystem-specific options, we don't call replace_mount_options
(thus we don't erase existing reported options).
Note that to properly report options after remount, the reiserfs
filesystem should implement the show_options method. Without the
show_options method, options changed with remount replace existing
options.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Add infrastructure for supporting get_nextdqblk() callback for VFS
quotas. Translate the operation into a callback to appropriate
filesystem and consequently to quota format callback.
Signed-off-by: Jan Kara <jack@suse.cz>
reiserfs_iget() returns either NULL or error code in ERR_PTR. And we
were only checking for NULL, so in case of some other error we will try
to dereference the ERR_PTR(-errno) thinking it to be a valid pointer.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mark those kmem allocations that are known to be easily triggered from
userspace as __GFP_ACCOUNT/SLAB_ACCOUNT, which makes them accounted to
memcg. For the list, see below:
- threadinfo
- task_struct
- task_delay_info
- pid
- cred
- mm_struct
- vm_area_struct and vm_region (nommu)
- anon_vma and anon_vma_chain
- signal_struct
- sighand_struct
- fs_struct
- files_struct
- fdtable and fdtable->full_fds_bits
- dentry and external_name
- inode for all filesystems. This is the most tedious part, because
most filesystems overwrite the alloc_inode method.
The list is far from complete, so feel free to add more objects.
Nevertheless, it should be close to "account everything" approach and
keep most workloads within bounds. Malevolent users will be able to
breach the limit, but this was possible even with the former "account
everything" approach (simply because it did not account everything in
fact).
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many file systems that implement the show_options hook fail to correctly
escape their output which could lead to unescaped characters (e.g. new
lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This
could lead to confusion, spoofed entries (resulting in things like
systemd issuing false d-bus "mount" notifications), and who knows what
else. This looks like it would only be the root user stepping on
themselves, but it's possible weird things could happen in containers or
in other situations with delegated mount privileges.
Here's an example using overlay with setuid fusermount trusting the
contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use
of "sudo" is something more sneaky:
$ BASE="ovl"
$ MNT="$BASE/mnt"
$ LOW="$BASE/lower"
$ UP="$BASE/upper"
$ WORK="$BASE/work/ 0 0
none /proc fuse.pwn user_id=1000"
$ mkdir -p "$LOW" "$UP" "$WORK"
$ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt
$ cat /proc/mounts
none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0
none /proc fuse.pwn user_id=1000 0 0
$ fusermount -u /proc
$ cat /proc/mounts
cat: /proc/mounts: No such file or directory
This fixes the problem by adding new seq_show_option and
seq_show_option_n helpers, and updating the vulnerable show_option
handlers to use them as needed. Some, like SELinux, need to be open
coded due to unusual existing escape mechanisms.
[akpm@linux-foundation.org: add lost chunk, per Kees]
[keescook@chromium.org: seq_show_option should be using const parameters]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Jan Kara <jack@suse.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge second patchbomb from Andrew Morton:
- most of the rest of MM
- lots of misc things
- procfs updates
- printk feature work
- updates to get_maintainer, MAINTAINERS, checkpatch
- lib/ updates
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (96 commits)
exit,stats: /* obey this comment */
coredump: add __printf attribute to cn_*printf functions
coredump: use from_kuid/kgid when formatting corename
fs/reiserfs: remove unneeded cast
NILFS2: support NFSv2 export
fs/befs/btree.c: remove unneeded initializations
fs/minix: remove unneeded cast
init/do_mounts.c: add create_dev() failure log
kasan: remove duplicate definition of the macro KASAN_FREE_PAGE
fs/efs: femove unneeded cast
checkpatch: emit "NOTE: <types>" message only once after multiple files
checkpatch: emit an error when there's a diff in a changelog
checkpatch: validate MODULE_LICENSE content
checkpatch: add multi-line handling for PREFER_ETHER_ADDR_COPY
checkpatch: suggest using eth_zero_addr() and eth_broadcast_addr()
checkpatch: fix processing of MEMSET issues
checkpatch: suggest using ether_addr_equal*()
checkpatch: avoid NOT_UNIFIED_DIFF errors on cover-letter.patch files
checkpatch: remove local from codespell path
checkpatch: add --showfile to allow input via pipe to show filenames
...
With the planned cgroup writeback support, backing-dev related
declarations will be more widely used across block and cgroup;
unfortunately, including backing-dev.h from include/linux/blkdev.h
makes cyclic include dependency quite likely.
This patch separates out backing-dev-defs.h which only has the
essential definitions and updates blkdev.h to include it. c files
which need access to more backing-dev details now include
backing-dev.h directly. This takes backing-dev.h off the common
include dependency chain making it a lot easier to use it across block
and cgroup.
v2: fs/fat build failure fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>
Pull fourth vfs update from Al Viro:
"d_inode() annotations from David Howells (sat in for-next since before
the beginning of merge window) + four assorted fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
RCU pathwalk breakage when running into a symlink overmounting something
fix I_DIO_WAKEUP definition
direct-io: only inc/dec inode->i_dio_count for file systems
fs/9p: fix readdir()
VFS: assorted d_backing_inode() annotations
VFS: fs/inode.c helpers: d_inode() annotations
VFS: fs/cachefiles: d_backing_inode() annotations
VFS: fs library helpers: d_inode() annotations
VFS: assorted weird filesystems: d_inode() annotations
VFS: normal filesystems (and lustre): d_inode() annotations
VFS: security/: d_inode() annotations
VFS: security/: d_backing_inode() annotations
VFS: net/: d_inode() annotations
VFS: net/unix: d_backing_inode() annotations
VFS: kernel/: d_inode() annotations
VFS: audit: d_backing_inode() annotations
VFS: Fix up some ->d_inode accesses in the chelsio driver
VFS: Cachefiles should perform fs modifications on the top layer only
VFS: AF_UNIX sockets should call mknod on the top layer only
that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Create new internal interface for getting information about quota which
contains everything needed for both VFS quotas and XFS quotas. Make VFS
use this and hook it up to Q_GETINFO.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
When resirefs is trying to mount a partition, it creates a commit
workqueue (sbi->commit_wq). But when mount fails later, the workqueue
is not freed.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: auxsvr@gmail.com
Reported-by: Benoît Monin <benoit.monin@gmx.fr>
Cc: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org # >= 3.16
Cc: reiserfs-devel@vger.kernel.org
Fixes: 797d9016ce
Signed-off-by: Jan Kara <jack@suse.cz>
MAXQUOTAS value defines maximum number of quota types VFS supports.
This isn't necessarily the number of types reiserfs supports and with
addition of project quotas these two numbers stop matching. So make
reiserfs use its private definition.
CC: reiserfs-devel@vger.kernel.org
CC: Jeff Mahoney <jeffm@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Pull quota, reiserfs, UDF updates from Jan Kara:
"Scalability improvements for quota, a few reiserfs fixes, and couple
of misc cleanups (udf, ext2)"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
reiserfs: Fix use after free in journal teardown
reiserfs: fix corruption introduced by balance_leaf refactor
udf: avoid redundant memcpy when writing data in ICB
fs/udf: re-use hex_asc_upper_{hi,lo} macros
fs/quota: kernel-doc warning fixes
udf: use linux/uaccess.h
fs/ext2/super.c: Drop memory allocation cast
quota: remove dqptr_sem
quota: simplify remove_inode_dquot_ref()
quota: avoid unnecessary dqget()/dqput() calls
quota: protect Q_GETFMT by dqonoff_mutex
If do_journal_release() races with do_journal_end() which requeues
delayed works for transaction flushing, we can leave work items for
flushing outstanding transactions queued while freeing them. That
results in use after free and possible crash in run_timers_softirq().
Fix the problem by not requeueing works if superblock is being shut down
(MS_ACTIVE not set) and using cancel_delayed_work_sync() in
do_journal_release().
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
The hash detection code uses long ugly macros multiple times to get the same
value. This patch cleans it up to be easier to read.
[JK: Fixed up path leak in find_hash_out()]
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The reiserfs code is littered with extra parens in places where the authors
may not have been certain about precedence of & vs ->. This patch cleans them
out.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
journal_mark_dirty doesn't need a separate sb argument; It's provided
by the transaction handle.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
journal_end doesn't need a separate sb argument; it's provided by the
transaction handle.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
journal_end takes a block count argument but doesn't actually use it
for anything. We can remove it.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This patch reformats comments in the reiserfs code to fit in 80 columns and
to follow the style rules.
There is no functional change but it helps make my eyes bleed less.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This patch does a quick search and replace:
B_N_PITEM_HEAD() -> item_head()
B_N_PDELIM_KEY() -> internal_key()
B_N_PKEY() -> leaf_key()
B_N_PITEM() -> item_body()
And the item_head version:
B_I_PITEM() -> ih_item_body()
I_ENTRY_COUNT() -> ih_entry_count()
And the treepath variants:
get_ih() -> tp_item_head()
PATH_PITEM_HEAD() -> tp_item_head()
get_item() -> tp_item_body()
... which makes the code much easier on the eyes.
I've also removed a few unused macros.
Checkpatch will complain about the 80 character limit for do_balan.c.
I've addressed that in a later patchset to split up balance_leaf().
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The reiserfs write lock hasn't been the BKL for some time. There's no
need to have different file systems queued up on the same workqueue.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
and COLLAPSE_RANGE fallocate operations, and scalability improvements
in the jbd2 layer and in xattr handling when the extended attributes
spill over into an external block.
Other than that, the usual clean ups and minor bug fixes.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"Major changes for 3.14 include support for the newly added ZERO_RANGE
and COLLAPSE_RANGE fallocate operations, and scalability improvements
in the jbd2 layer and in xattr handling when the extended attributes
spill over into an external block.
Other than that, the usual clean ups and minor bug fixes"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (42 commits)
ext4: fix premature freeing of partial clusters split across leaf blocks
ext4: remove unneeded test of ret variable
ext4: fix comment typo
ext4: make ext4_block_zero_page_range static
ext4: atomically set inode->i_flags in ext4_set_inode_flags()
ext4: optimize Hurd tests when reading/writing inodes
ext4: kill i_version support for Hurd-castrated file systems
ext4: each filesystem creates and uses its own mb_cache
fs/mbcache.c: doucple the locking of local from global data
fs/mbcache.c: change block and index hash chain to hlist_bl_node
ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate
ext4: refactor ext4_fallocate code
ext4: Update inode i_size after the preallocation
ext4: fix partial cluster handling for bigalloc file systems
ext4: delete path dealloc code in ext4_ext_handle_uninitialized_extents
ext4: only call sync_filesystm() when remounting read-only
fs: push sync_filesystem() down to the file system's remount_fs()
jbd2: improve error messages for inconsistent journal heads
jbd2: minimize region locked by j_list_lock in jbd2_journal_forget()
jbd2: minimize region locked by j_list_lock in journal_get_create_access()
...
init_inodecache is only called by __init init_reiserfs_fs.
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move prototype declaration to header file reiserfs/reiserfs.h from
reiserfs/super.c because they are used by more than one file.
This eliminates the following warning in reiserfs/bitmap.c:
fs/reiserfs/bitmap.c:647:6: warning: no previous prototype for `show_alloc_options' [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull ext3, reiserfs, udf & isofs fixes from Jan Kara:
"The contains a bunch of ext3 cleanups and minor improvements, major
reiserfs locking changes which should hopefully fix deadlocks
introduced by BKL removal, and udf/isofs changes to refuse mounting fs
rw instead of mounting it ro automatically which makes eject button
work as expected for all media (see the changelog for why userspace
should be ok with this change)"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
jbd: use a single printk for jbd_debug()
reiserfs: locking, release lock around quota operations
reiserfs: locking, handle nested locks properly
reiserfs: locking, push write lock out of xattr code
jbd: relocate assert after state lock in journal_commit_transaction()
udf: Refuse RW mount of the filesystem instead of making it RO
udf: Standardize return values in mount sequence
isofs: Refuse RW mount of the filesystem instead of making it RO
ext3: allow specifying external journal by pathname mount option
jbd: remove unneeded semicolon
Previous commits released the write lock across quota operations but
missed several places. In particular, the free operations can also
call into the file system code and take the write lock, causing
deadlocks.
This patch introduces some more helpers and uses them for quota call
sites. Without this patch applied, reiserfs + quotas runs into deadlocks
under anything more than trivial load.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
The reiserfs write lock replaced the BKL and uses similar semantics.
Frederic's locking code makes a distinction between when the lock is nested
and when it's being acquired/released, but I don't think that's the right
distinction to make.
The right distinction is between the lock being released at end-of-use and
the lock being released for a schedule. The unlock should return the depth
and the lock should restore it, rather than the other way around as it is now.
This patch implements that and adds a number of places where the lock
should be dropped.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
The reiserfs xattr code doesn't need the write lock and sleeps all over
the place. We can simplify the locking by releasing it and reacquiring
after the xattr call.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Since remove_proc_entry() started to wait for IO in progress (i.e.
since 2007 or so), the locking in fs/reiserfs/proc.c became wrong;
if procfs read happens between the moment when umount() locks the
victim superblock and removal of /proc/fs/reiserfs/<device>/*,
we'll get a deadlock - read will wait for s_umount (in sget(),
called by r_start()), while umount will wait in remove_proc_entry()
for that read to finish, holding s_umount all along.
Fortunately, the same change allows a much simpler race avoidance -
all we need to do is remove the procfs entries in the very beginning
of reiserfs ->kill_sb(); that'll guarantee that pointer to superblock
will remain valid for the duration for procfs IO, so we don't need
sget() to keep the sucker alive. As the matter of fact, we can
get rid of the home-grown iterator completely, and use single_open()
instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Modify the request_module to prefix the file system type with "fs-"
and add aliases to all of the filesystems that can be built as modules
to match.
A common practice is to build all of the kernel code and leave code
that is not commonly needed as modules, with the result that many
users are exposed to any bug anywhere in the kernel.
Looking for filesystems with a fs- prefix limits the pool of possible
modules that can be loaded by mount to just filesystems trivially
making things safer with no real cost.
Using aliases means user space can control the policy of which
filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf
with blacklist and alias directives. Allowing simple, safe,
well understood work-arounds to known problematic software.
This also addresses a rare but unfortunate problem where the filesystem
name is not the same as it's module name and module auto-loading
would not work. While writing this patch I saw a handful of such
cases. The most significant being autofs that lives in the module
autofs4.
This is relevant to user namespaces because we can reach the request
module in get_fs_type() without having any special permissions, and
people get uncomfortable when a user specified string (in this case
the filesystem type) goes all of the way to request_module.
After having looked at this issue I don't think there is any
particular reason to perform any filtering or permission checks beyond
making it clear in the module request that we want a filesystem
module. The common pattern in the kernel is to call request_module()
without regards to the users permissions. In general all a filesystem
module does once loaded is call register_filesystem() and go to sleep.
Which means there is not much attack surface exposed by loading a
filesytem module unless the filesystem is mounted. In a user
namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT,
which most filesystems do not set today.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reported-by: Kees Cook <keescook@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Calls into highlevel quota code cannot happen under the write lock. These
calls take dqio_mutex which ranks above write lock. So drop write lock
before calling back into quota code.
CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>
