Make file->f_path always point to the overlay dentry so that the path in
/proc/pid/fd is correct and to ensure that label-based LSMs have access to the
overlay as well as the underlay (path-based LSMs probably don't need it).
Using my union testsuite to set things up, before the patch I see:
[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
...
lr-x------. 1 root root 64 Jun 5 14:38 5 -> /a/foo107
[root@andromeda union-testsuite]# stat /mnt/a/foo107
...
Device: 23h/35d Inode: 13381 Links: 1
...
[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
...
Device: 23h/35d Inode: 13381 Links: 1
...
After the patch:
[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
...
lr-x------. 1 root root 64 Jun 5 14:22 5 -> /mnt/a/foo107
[root@andromeda union-testsuite]# stat /mnt/a/foo107
...
Device: 23h/35d Inode: 40346 Links: 1
...
[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
...
Device: 23h/35d Inode: 40346 Links: 1
...
Note the change in where /proc/$$/fd/5 points to in the ls command. It was
pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107
(which is correct).
The inode accessed, however, is the lower layer. The union layer is on device
25h/37d and the upper layer on 24h/36d.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Call ovl_drop_write() earlier in ovl_dentry_open() before we call vfs_open()
as we've done the copy up for which we needed the freeze-write lock by that
point.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add last missing line in commit "cdd9eefdf905"
("fs/ufs: restore s_lock mutex")
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
See "ext2: Do not update mtime of a moved directory" (and followup in
"ext2: fix unbalanced kmap()/kunmap()") for background; this is UFS
equivalent - the same problem exists here.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We are already serialized by ->i_mutex and operations on different
directories are independent. These calls are just rudiments of
blind BKL conversion and they should've been removed back then.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit e4502c63f5 (ufs: deal with nfsd/iget races) made ufs
create inodes with I_NEW flag set. However ufs_mkdir() never cleared
this flag. Thus if someone ever tried to lookup the directory by inode
number, he would deadlock waiting for I_NEW to be cleared. Luckily this
mostly happens only if the filesystem is exported over NFS since
otherwise we have the inode attached to dentry and don't look it up by
inode number. In rare cases dentry can get freed without inode being
freed and then we'd hit the deadlock even without NFS export.
Fix the problem by clearing I_NEW before instantiating new directory
inode.
Fixes: e4502c63f5
Reported-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit e4502c63f5 (ufs: deal with nfsd/iget races) introduced
unlock_new_inode() call into ufs_add_nondir(). However that function
gets called also from ufs_link() which hands it already initialized
inode and thus unlock_new_inode() complains. The problem is harmless but
annoying.
Fix the problem by opencoding necessary stuff in ufs_link()
Fixes: e4502c63f5
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 0244756edc ("ufs: sb mutex merge + mutex_destroy") generated
deadlocks in read/write mode on mkdir.
This patch partially reverts it keeping fixes by Andrew Morton and
mutex_destroy()
[AV: fixed a missing bit in ufs_remount()]
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reported-by: Ian Campbell <ian.campbell@citrix.com>
Suggested-by: Jan Kara <jack@suse.cz>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Roger Pau Monne <roger.pau@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This reverts commit 9ef7db7f38 ("ufs: fix deadlocks introduced by sb
mutex merge") That patch tried to solve commit 0244756edc ("ufs: sb
mutex merge + mutex_destroy") which is itself partially reverted due to
multiple deadlocks.
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Suggested-by: Jan Kara <jack@suse.cz>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Roger Pau Monne <roger.pau@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
when we find that a child has died while we'd been trying to ascend,
we should go into the first live sibling itself, rather than its sibling.
Off-by-one in question had been introduced in "deal with deadlock in
d_walk()" and the fix needs to be backported to all branches this one
has been backported to.
Cc: stable@vger.kernel.org # 3.2 and later
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
these guys are always declared next to each other; might as well put
the former (pointer to previous instance) into the latter and simplify
the calling conventions for {set,restore}_nameidata()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
a) make it reject ERR_PTR() for name
b) make it putname(name) on all other failure exits
c) make it return name on success
again, simplifies the callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
a) make it reject ERR_PTR() for name
b) make it putname(name) upon return in all other cases.
seriously simplifies the callers...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Otherwise we are risking a hard error where nonlazy restart would be the right
thing to do; it's a very narrow race with mount --move and most of the time it
ends up being completely harmless, but it's possible to construct a case when
we'll get a bogus hard error instead of falling back to non-lazy walk...
For one thing, when crossing _into_ overmount of parent we need to check for
mount_lock bumps when we get NULL from __lookup_mnt() as well.
For another, and less exotically, we need to make sure that the data fetched
in follow_up_rcu() had been consistent. ->mnt_mountpoint is pinned for as
long as it is a mountpoint, but we need to check mount_lock after fetching
to verify that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The guidelines for adding automount support to a filesystem
in filesystems/automount-support.txt is out or date.
filesystems/autofs4.txt contains more current text, so replace
the out-of-date content with a reference to that.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
touch_atime is not RCU-safe, and so cannot be called on an RCU walk.
However, in situations where RCU-walk makes a difference, the symlink
will likely to accessed much more often than it is useful to update
the atime.
So split out the test of "Does the atime actually need to be updated"
into atime_needs_update(), and have get_link() unlazy if it finds that
it will need to do that update.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We are almost done - primitives for leaving RCU mode are aware of nd->stack
now, a new primitive for going to non-RCU mode when we have a symlink on hands
added.
The thing we are heavily relying upon is that *any* unlazy failure will be
shortly followed by terminate_walk(), with no access to nameidata in between.
So it's enough to leave the things in a state terminate_walk() would cope with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
same as legitimize_mnt(), except that it does *not* drop and regain
rcu_read_lock; return values are
0 => grabbed a reference, we are fine
1 => failed, just go away
-1 => failed, go away and mntput(bastard) when outside of rcu_read_lock
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We *can't* call that audit garbage in RCU mode - it's doing a weird
mix of allocations (GFP_NOFS, immediately followed by GFP_KERNEL)
and I'm not touching that... thing again.
So if this security sclero^Whardening feature gets triggered when
we are in RCU mode, tough - we'll fail with -ECHILD and have
everything restarted in non-RCU mode. Only to hit the same test
and fail, this time with EACCES and with (oh, rapture) an audit spew
produced.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
very simple - just make path_put() conditional on !RCU.
Note that right now it doesn't get called in RCU mode -
we leave it before getting anything into stack.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
inode_follow_link now takes an inode and rcu flag as well as the
dentry.
inode is used in preference to d_backing_inode(dentry), particularly
in RCU-walk mode.
selinux_inode_follow_link() gets dentry_has_perm() and
inode_has_perm() open-coded into it so that it can call
avc_has_perm_flags() in way that is safe if LOOKUP_RCU is set.
Calling avc_has_perm_flags() with rcu_read_lock() held means
that when avc_has_perm_noaudit calls avc_compute_av(), the attempt
to rcu_read_unlock() before calling security_compute_av() will not
actually drop the RCU read-lock.
However as security_compute_av() is completely in a read_lock()ed
region, it should be safe with the RCU read-lock held.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This allows MAY_NOT_BLOCK to be passed, in RCU-walk mode, through
the new avc_has_perm_flags() to avc_audit() and thence the slow_avc_audit.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make use of d_backing_inode() in pathwalk to gain access to an
inode or dentry that's on a lower layer.
Signed-off-by: David Howells <dhowells@redhat.com>
