Carlos Maiolino [Thu, 25 Jun 2015 15:25:58 +0000 (12:25 -0300)]
vfs: avoid creation of inode number 0 in get_next_ino
currently, get_next_ino() is able to create inodes with inode number = 0.
This have a bad impact in the filesystems relying in this function to generate
inode numbers.
While there is no problem at all in having inodes with number 0, userspace tools
which handle file management tasks can have problems handling these files, like
for example, the impossiblity of users to delete these files, since glibc will
ignore them. So, I believe the best way is kernel to avoid creating them.
This problem has been raised previously, but the old thread didn't have any
other update for a year+, and I've seen too many users hitting the same issue
regarding the impossibility to delete files while using filesystems relying on
this function. So, I'm starting the thread again, with the same patch
that I believe is enough to address this problem.
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 29 Jun 2015 16:07:04 +0000 (12:07 -0400)]
namei: make set_root_rcu() return void
The only caller that cares about its return value can just
as easily pick it from nd->root_seq itself. We used to just
calculate it and return to caller, but these days we are
storing it in nd->root_seq in all cases.
Rasmus Villemoes [Thu, 19 Mar 2015 11:28:04 +0000 (12:28 +0100)]
fs: cleanup slight list_entry abuse
list_entry is just a wrapper for container_of, but it is arguably
wrong (and slightly confusing) to use it when the pointed-to struct
member is not a struct list_head. Use container_of directly instead.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Jan Kara [Thu, 21 May 2015 14:05:56 +0000 (16:05 +0200)]
xfs: Correctly lock inode when removing suid and file capabilities
Currently XFS calls file_remove_privs() without holding i_mutex. This is
wrong because that function can end up messing with file permissions and
file capabilities stored in xattrs for which we need i_mutex held.
Fix the problem by grabbing iolock exclusively when we will need to
change anything in permissions / xattrs.
Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Jan Kara [Thu, 21 May 2015 14:05:55 +0000 (16:05 +0200)]
fs: Call security_ops->inode_killpriv on truncate
Comment in include/linux/security.h says that ->inode_killpriv() should
be called when setuid bit is being removed and that similar security
labels (in fact this applies only to file capabilities) should be
removed at this time as well. However we don't call ->inode_killpriv()
when we remove suid bit on truncate.
We fix the problem by calling ->inode_need_killpriv() and subsequently
->inode_killpriv() on truncate the same way as we do it on file write.
After this patch there's only one user of should_remove_suid() - ocfs2 -
and indeed it's buggy because it doesn't call ->inode_killpriv() on
write. However fixing it is difficult because of special locking
constraints.
Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Jan Kara [Thu, 21 May 2015 14:05:54 +0000 (16:05 +0200)]
fs: Provide function telling whether file_remove_privs() will do anything
Provide function telling whether file_remove_privs() will do anything.
Currently we only have should_remove_suid() and that does something
slightly different.
Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Jan Kara [Thu, 21 May 2015 14:05:53 +0000 (16:05 +0200)]
fs: Rename file_remove_suid() to file_remove_privs()
file_remove_suid() is a misnomer since it removes also file capabilities
stored in xattrs and sets S_NOSEC flag. Also should_remove_suid() tells
something else than whether file_remove_suid() call is necessary which
leads to bugs.
Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Jan Kara [Thu, 21 May 2015 14:05:52 +0000 (16:05 +0200)]
fs: Fix S_NOSEC handling
file_remove_suid() could mistakenly set S_NOSEC inode bit when root was
modifying the file. As a result following writes to the file by ordinary
user would avoid clearing suid or sgid bits.
Fix the bug by checking actual mode bits before setting S_NOSEC.
CC: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Dan Carpenter [Thu, 18 Jun 2015 23:00:55 +0000 (09:00 +1000)]
fs/posix_acl.c: make posix_acl_create() safer and cleaner
If posix_acl_create() returns an error code then "*acl" and "*default_acl"
can be uninitialized or point to freed memory. This is a dangerous thing
to do. For example, it causes a problem in ocfs2_reflink():
fs/ocfs2/refcounttree.c:4327 ocfs2_reflink()
error: potentially using uninitialized 'default_acl'.
I've re-written this so we set the pointers to NULL at the start. I've
added a temporary "clone" variable to hold the value of "*acl" until end.
Setting them to NULL means means we don't need the "no_acl" label. We may
as well remove the "apply_umask" stuff forward and remove that label as
well.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Howells [Thu, 18 Jun 2015 13:32:31 +0000 (14:32 +0100)]
overlayfs: Make f_path always point to the overlay and f_inode to the underlay
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:
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>
David Howells [Thu, 18 Jun 2015 13:32:23 +0000 (14:32 +0100)]
overlay: Call ovl_drop_write() earlier in ovl_dentry_open()
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>
Al Viro [Tue, 16 Jun 2015 05:56:23 +0000 (01:56 -0400)]
ufs: don't touch mtime/ctime of directory being moved
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.
Al Viro [Tue, 16 Jun 2015 05:50:43 +0000 (01:50 -0400)]
ufs: don't bother with lock_ufs()/unlock_ufs() for directory access
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.
Jan Kara [Tue, 2 Jun 2015 09:26:34 +0000 (11:26 +0200)]
ufs: Fix possible deadlock when looking up directories
Commit e4502c63f56aeca88 (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: e4502c63f56aeca887ced37f24e0def1ef11cec8 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>
Jan Kara [Mon, 1 Jun 2015 12:52:04 +0000 (14:52 +0200)]
ufs: Fix warning from unlock_new_inode()
Commit e4502c63f56aeca88 (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: e4502c63f56aeca887ced37f24e0def1ef11cec8 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Fabian Frederick [Wed, 10 Jun 2015 00:09:32 +0000 (10:09 +1000)]
fs/ufs: restore s_lock mutex
Commit 0244756edc4b98c ("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>
Fabian Frederick [Wed, 10 Jun 2015 00:09:32 +0000 (10:09 +1000)]
fs/ufs: revert "ufs: fix deadlocks introduced by sb mutex merge"
This reverts commit 9ef7db7f38d0 ("ufs: fix deadlocks introduced by sb
mutex merge") That patch tried to solve commit 0244756edc4b98c ("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>
Al Viro [Fri, 29 May 2015 03:09:19 +0000 (23:09 -0400)]
d_walk() might skip too much
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>
Al Viro [Wed, 13 May 2015 11:28:08 +0000 (07:28 -0400)]
namei: move saved_nd pointer into struct nameidata
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()
Al Viro [Tue, 12 May 2015 16:22:47 +0000 (12:22 -0400)]
namei: be careful with mountpoint crossings in follow_dotdot_rcu()
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.
NeilBrown [Mon, 23 Mar 2015 02:37:38 +0000 (13:37 +1100)]
Documentation: remove outdated information from automount-support.txt
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>
NeilBrown [Mon, 23 Mar 2015 02:37:40 +0000 (13:37 +1100)]
VFS/namei: make the use of touch_atime() in get_link() RCU-safe.
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>
Al Viro [Sat, 9 May 2015 16:55:43 +0000 (12:55 -0400)]
namei: make unlazy_walk and terminate_walk handle nd->stack, add unlazy_link
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.
Al Viro [Fri, 8 May 2015 15:43:53 +0000 (11:43 -0400)]
new helper: __legitimize_mnt()
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
Al Viro [Fri, 8 May 2015 00:37:40 +0000 (20:37 -0400)]
namei: make may_follow_link() safe in RCU mode
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.
Al Viro [Fri, 8 May 2015 00:32:22 +0000 (20:32 -0400)]
namei: make put_link() RCU-safe
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.
NeilBrown [Mon, 23 Mar 2015 02:37:39 +0000 (13:37 +1100)]
security: make inode_follow_link RCU-walk aware
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>
Al Viro [Fri, 8 May 2015 21:37:07 +0000 (17:37 -0400)]
namei: lift link_path_walk() call out of trailing_symlink()
Make trailing_symlink() return the pathname to traverse or ERR_PTR(-E...).
A subtle point is that for "magic" symlinks it returns "" now - that
leads to link_path_walk("", nd), which is immediately returning 0 and
we are back to the treatment of the last component, at whereever the
damn thing has left us.
Reduces the stack footprint - link_path_walk() called on more shallow
stack now.
Al Viro [Fri, 8 May 2015 21:19:59 +0000 (17:19 -0400)]
namei: path_init() calling conventions change
* lift link_path_walk() into callers; moving it down into path_init()
had been a mistake. Stack footprint, among other things...
* do _not_ call path_cleanup() after path_init() failure; on all failure
exits out of it we have nothing for path_cleanup() to do
* have path_init() return pathname or ERR_PTR(-E...)
Al Viro [Sun, 10 May 2015 15:50:01 +0000 (11:50 -0400)]
namei: take increment of nd->depth into pick_link()
Makes the situation much more regular - we avoid a strange state
when the element just after the top of stack is used to store
struct path of symlink, but isn't counted in nd->depth. This
is much more regular, so the normal failure exits, etc., work
fine.
Al Viro [Fri, 8 May 2015 20:28:42 +0000 (16:28 -0400)]
namei: fold put_link() into the failure case of complete_walk()
... and don't open-code unlazy_walk() in there - the only reason
for that is to avoid verfication of cached nd->root, which is
trivially avoided by discarding said cached nd->root first.
Al Viro [Sun, 10 May 2015 15:01:00 +0000 (11:01 -0400)]
namei: take the treatment of absolute symlinks to get_link()
rather than letting the callers handle the jump-to-root part of
semantics, do it right in get_link() and return the rest of the
body for the caller to deal with - at that point it's treated
the same way as relative symlinks would be. And return NULL
when there's no "rest of the body" - those are treated the same
as pure jump symlink would be.
Al Viro [Sun, 10 May 2015 14:50:41 +0000 (10:50 -0400)]
namei: simpler treatment of symlinks with nothing other that / in the body
Instead of saving name and branching to OK:, where we'll immediately restore
it, and call walk_component() with WALK_PUT|WALK_GET and nd->last_type being
LAST_BIND, which is equivalent to put_link(nd), err = 0, we can just treat
that the same way we'd treat procfs-style "jump" symlinks - do put_link(nd)
and move on.
Al Viro [Sun, 10 May 2015 14:43:46 +0000 (10:43 -0400)]
namei: simplify failure exits in get_link()
when cookie is NULL, put_link() is equivalent to path_put(), so
as soon as we'd set last->cookie to NULL, we can bump nd->depth and
let the normal logics in terminate_walk() to take care of cleanups.
Al Viro [Wed, 22 Apr 2015 14:30:08 +0000 (10:30 -0400)]
namei: simplify the callers of follow_managed()
now that it gets nameidata, no reason to have setting LOOKUP_JUMPED on
mountpoint crossing and calling path_put_conditional() on failures
done in every caller.
NeilBrown [Mon, 23 Mar 2015 02:37:38 +0000 (13:37 +1100)]
VFS: replace {, total_}link_count in task_struct with pointer to nameidata
task_struct currently contains two ad-hoc members for use by the VFS:
link_count and total_link_count. These are only interesting to fs/namei.c,
so exposing them explicitly is poor layering. Incidentally, link_count
isn't used anymore, so it can just die.
This patches replaces those with a single pointer to 'struct nameidata'.
This structure represents the current filename lookup of which
there can only be one per process, and is a natural place to
store total_link_count.
This will allow the current "nameidata" argument to all
follow_link operations to be removed as current->nameidata
can be used instead in the _very_ few instances that care about
it at all.
As there are occasional circumstances where pathname lookup can
recurse, such as through kern_path_locked, we always save and old
current->nameidata (if there is one) when setting a new value, and
make sure any active link_counts are preserved.
follow_mount and follow_automount now get a 'struct nameidata *'
rather than 'int flags' so that they can directly access
total_link_count, rather than going through 'current'.
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 21:47:11 +0000 (17:47 -0400)]
namei: new calling conventions for walk_component()
instead of a single flag (!= 0 => we want to follow symlinks) pass
two bits - WALK_GET (want to follow symlinks) and WALK_PUT (put_link()
once we are done looking at the name). The latter matters only for
success exits - on failure the caller will discard everything anyway.
Suggestions for better variant are welcome; what this thing aims for
is making sure that pending put_link() is done *before* walk_component()
decides to pick a symlink up, rather than between picking it up and
acting upon it. See the next commit for payoff.
Al Viro [Mon, 4 May 2015 12:34:59 +0000 (08:34 -0400)]
namei: have terminate_walk() do put_link() on everything left
All callers of terminate_walk() are followed by more or less
open-coded eqiuvalent of "do put_link() on everything left
in nd->stack". Better done in terminate_walk() itself, and
when we go for RCU symlink traversal we'll have to do it
there anyway.
Al Viro [Mon, 4 May 2015 12:26:45 +0000 (08:26 -0400)]
namei: take put_link() into {lookup,mountpoint,do}_last()
rationale: we'll need to have terminate_walk() do put_link() on
everything, which will mean that in some cases ..._last() will do
put_link() anyway. Easier to have them do it in all cases.
Al Viro [Mon, 4 May 2015 11:53:00 +0000 (07:53 -0400)]
namei: lift (open-coded) terminate_walk() in follow_dotdot_rcu() into callers
follow_dotdot_rcu() does an equivalent of terminate_walk() on failure;
shifting it into callers makes for simpler rules and those callers
already have terminate_walk() on other failure exits.
Al Viro [Mon, 4 May 2015 01:30:27 +0000 (21:30 -0400)]
namei: we never need more than MAXSYMLINKS entries in nd->stack
The only reason why we needed one more was that purely nested
MAXSYMLINKS symlinks could lead to path_init() using that many
entries in addition to nd->stack[0] which it left unused.
That can't happen now - path_init() starts with entry 0 (and
trailing_symlink() is called only when we'd already encountered
one symlink, so no more than MAXSYMLINKS-1 are left).
Al Viro [Mon, 4 May 2015 01:27:36 +0000 (21:27 -0400)]
link_path_walk: end of nd->depth massage
get rid of orig_depth - we only use it on error exit to tell whether
to stop doing put_link() when depth reaches 0 (call from path_init())
or when it reaches 1 (call from trailing_symlink()). However, in
the latter case the caller would immediately follow with one more
put_link(). Just keep doing it until the depth reaches zero (and
simplify trailing_symlink() as the result).
Al Viro [Mon, 4 May 2015 01:21:44 +0000 (21:21 -0400)]
link_path_walk: nd->depth massage, part 10
Get rid of orig_depth checks in OK: logics. If nd->depth is
zero, we had been called from path_init() and we are done.
If it is greater than 1, we are not done, whether we'd been
called from path_init() or trailing_symlink(). And in
case when it's 1, we might have been called from path_init()
and reached the end of nested symlink (in which case
nd->stack[0].name will point to the rest of pathname and
we are not done) or from trailing_symlink(), in which case
we are done.
Just have trailing_symlink() leave NULL in nd->stack[0].name
and use that to discriminate between those cases.
projects / linux-beck.git / log