just have hypfs_create_file() do the usual simple_start_creating()/
d_make_persistent()/simple_done_creating() and that's it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
hypfs dentries end up with refcount 2 when they are not busy.
Refcount 1 is enough to keep them pinned, and going that way
allows to simplify things nicely:
* don't need to drop an extra reference before the
call of kill_litter_super() in ->kill_sb(); all we need
there is to reset the cleanup list - everything on it will
be taken out automatically.
* we can make use of simple_recursive_removal() on
tree rebuilds; just make sure that only children of root
end up in the cleanup list and hypfs_delete_tree() becomes
much simpler
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All files are regular; ep0 is there all along, other ep* may appear
and go away during the filesystem lifetime; all of those are guaranteed
to be gone by the time we umount it.
Object creation is in ffs_sb_create_file(), removals - at ->kill_sb()
time (for ep0) or by simple_remove_by_name() from ffs_epfiles_destroy()
(for the rest of them).
Switch ffs_sb_create_file() to simple_start_creating()/d_make_persistent()/
simple_done_creating() and that's it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
No need to return dentry from ffs_sb_create_file() or keep it around
afterwards.
To avoid subtle issues with getting to ffs from epfiles in
ffs_epfiles_destroy(), pass the superblock as explicit argument.
Callers have it anyway.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
ffs_epfile_open() can race with removal, ending up with file->private_data
pointing to freed object.
There is a total count of opened files on functionfs (both ep0 and
dynamic ones) and when it hits zero, dynamic files get removed.
Unfortunately, that removal can happen while another thread is
in ffs_epfile_open(), but has not incremented the count yet.
In that case open will succeed, leaving us with UAF on any subsequent
read() or write().
The root cause is that ffs->opened is misused; atomic_dec_and_test() vs.
atomic_add_return() is not a good idea, when object remains visible all
along.
To untangle that
* serialize openers on ffs->mutex (both for ep0 and for dynamic files)
* have dynamic ones use atomic_inc_not_zero() and fail if we had
zero ->opened; in that case the file we are opening is doomed.
* have the inodes of dynamic files marked on removal (from the
callback of simple_recursive_removal()) - clear ->i_private there.
* have open of dynamic ones verify they hadn't been already removed,
along with checking that state is FFS_ACTIVE.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... otherwise we just might free ffs with ffs->reset_work
still on queue. That needs to be done after ffs_data_reset() -
that's the cutoff point for configfs accesses (serialized
on gadget_info->lock), which is where the schedule_work()
would come from.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
A reference is held by the superblock (it's dropped in ffs_kill_sb())
and filesystem will not get to ->kill_sb() while there are any opened
files, TYVM...
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
ffs_data_closed() has a seriously confusing logics in it: in addition
to the normal "decrement a counter and do some work if it hits zero"
there's "... and if it has somehow become negative, do that" bit.
It's not a race, despite smelling rather fishy. What really happens
is that in addition to "call that on close of files there, to match
the increments of counter on opens" there's one call in ->kill_sb().
Counter starts at 0 and never goes negative over the lifetime of
filesystem (or we have much worse problems everywhere - ->release()
call of some file somehow unpaired with successful ->open() of the
same). At the filesystem shutdown it will be 0 or, again, we have
much worse problems - filesystem instance destroyed with files on it
still open. In other words, at that call and at that call alone
the decrement would go from 0 to -1, hitting that chunk (and not
hitting the "if it hits 0" part).
So that check is a weirdly spelled "called from ffs_kill_sb()".
Just expand the call in the latter and kill the misplaced chunk
in ffs_data_closed().
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Tree has invariant part + two subtrees that get replaced upon each
policy load. Invariant parts stay for the lifetime of filesystem,
these two subdirs - from policy load to policy load (serialized
on lock_rename(root, ...)).
All object creations are via d_alloc_name()+d_add() inside selinuxfs,
all removals are via simple_recursive_removal().
Turn those d_add() into d_make_persistent()+dput() and that's mostly it.
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Tested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
allocating dentry after the inode has been set up reduces the amount
of boilerplate - "attach this inode under that name and this parent
or drop inode in case of failure" simplifies quite a few places.
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Tested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't bother to store the dentry of /policy_capabilities - it belongs
to invariant part of tree and we only use it to populate that directory,
so there's no reason to keep it around afterwards.
Same situation as with /avc, /ss, etc. There are two directories that
get replaced on policy load - /class and /booleans. These we need to
stash (and update the pointers on policy reload); /policy_capabilities
is not in the same boat.
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Tested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
removals are done with locked_recursive_removal(); switch creations to
simple_start_creating()/d_make_persistent()/simple_done_creating() and
take them to a helper (add_entry()), while we are at it - simpler control
flow that way.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
creation/removal is via normal VFS paths; make ->mkdir() and ->symlink()
use d_make_persistent(); ->rmdir() and ->unlink() - d_make_discardable()
instead of dput() and that's it.
d_make_persistent() works for unhashed just fine...
Note that only persistent dentries are ever hashed there; unusual absense
of ->d_delete() in dentry_operations is due to that - anything that has
refcount reach 0 will be unhashed there, so it won't get to checking
->d_delete anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Objects are created either by d_alloc_name()+d_add() (in
binderfs_ctl_create()) or by simple_start_creating()+d_instantiate().
Removals are by simple_recurisive_removal().
Switch d_add()/d_instantiate() to d_make_persistent() + dput().
Voila - kill_litter_super() is not needed anymore.
Fold dput()+unlocking the parent into simple_done_creating(), while
we are at it.
NOTE: return value of binderfs_create_file() is borrowed; it may get
stored in proc->binderfs_entry. See binder_release()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
It's called once, during binderfs mount, right after allocating
root dentry. Checking that it hadn't been already called is
only obfuscating things.
Looks like that bogosity had been copied from devpts...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Two kinds of objects there - ptmx and everything else (pty). The former is
created on mount and kept until the fs shutdown; the latter get created
and removed by tty layer (the references are borrowed into tty->driver_data).
The reference to ptmx dentry is also kept, but we only ever use it to
find ptmx inode on remount.
* turn d_add() into d_make_persistent() + dput() both in mknod_ptmx() and
in devpts_pty_new().
* turn dput() to d_make_discardable() in devpts_pty_kill().
* switch mknod_ptmx() to simple_{start,done}_creating().
* instead of storing in pts_fs_info a reference to ptmx dentry, store a reference
to its inode, seeing that this is what we use it for.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
static contents for each "service processor", whatever the fuck it is.
Congruent subdirectories of root, created at mount time, taken out
by kill_litter_super(). All dentries created with d_alloc_name() and are
left pinned. The odd part is that the list of service providers is
assumed to be unchanging - no locking, nothing to handle removals or
extra elements added later on.
... and it's a PCI device. If you ever tell it to remove an instance,
you are fucked - it doesn't bother with removing its directory from filesystem,
it has a strange check that presumably wanted to be a check for removed
devices, but it had never been fleshed out.
Anyway, d_add() -> d_make_persistent()+dput() in ibmasmfs_create_dir() and
ibmasmfs_create_file(), and make the latter return int - no need to even
borrow that dentry, callers completely ignore it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
have spufs_new_file() use d_make_persistent() instead of d_add() and
do an uncondition dput() in the caller; the rest is completely
straightforward.
[a braino in spufs_mkgang() fixed]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Initially filesystem is populated with d_alloc_name() + d_add().
That becomes d_alloc_name() + d_make_persistent() + dput().
Dynamic creation is switched to d_make_persistent();
removal - to simple_unlink() (no point open-coding it in
efivarfs_unlink(), better call it there)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
we'd already verified that DEBUGFS_ALLOW_API was there in
start_creating() - it would've failed otherwise
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
similar to tracefs - simulation of normal codepath for creation,
simple_recursive_removal() for removal.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
A mix of persistent and non-persistent dentries in there. Strictly
speaking, no need for kill_litter_super() anyway - it pins an internal
mount whenever a persistent dentry is created, so at fs shutdown time
there won't be any to deal with.
However, let's make it explicit - replace d_instantiate() with
d_make_persistent() + dput() (the latter in tracefs_end_creating(),
where it folds with inode_unlock() into simple_done_creating())
for dentries we want persistent and have d_make_discardable() done
either by simple_recursive_removal() (used by tracefs_remove())
or explicitly in eventfs_remove_events_dir().
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
object creation by d_alloc_name()+d_add() in pstore_mkfile(), removal -
via normal VFS codepaths (with ->unlink() using simple_unlink()) or
in pstore_put_backend_records() via locked_recursive_removal()
Replace d_add() with d_make_persistent()+dput() - that's what really
happens there. The reference that goes into record->dentry is valid
only until the unlink (and explicitly cleared by pstore_unlink()).
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
objects are created in fuse_ctl_add_dentry() by d_alloc_name()+d_add(),
removed by simple_remove_by_name().
What we return is a borrowed reference - it is valid until the call of
fuse_ctl_remove_conn() and we depend upon the exclusion (on fuse_mutex)
for safety. Return value is used only within the caller
(fuse_ctl_add_conn()).
Replace d_add() with d_make_persistent() + dput(). dput() is paired
with d_alloc_name() and return value is the result of d_make_persistent().
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All modifications via normal VFS codepaths; just take care of making
persistent in ->create() and ->mkdir() and that's it (removal side
doesn't need any changes, since it uses simple_rmdir() for ->rmdir()
and calls simple_unlink() from ->unlink()).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
object creation goes through the normal VFS paths or approximation
thereof (user_path_create()/done_path_create() in case of bpf_obj_do_pin(),
open-coded simple_{start,done}_creating() in bpf_iter_link_pin_kernel()
at mount time), removals go entirely through the normal VFS paths (and
->unlink() is simple_unlink() there).
Enough to have bpf_dentry_finalize() use d_make_persistent() instead
of dget() and we are done.
Convert bpf_iter_link_pin_kernel() to simple_{start,done}_creating(),
while we are at it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All modifications via normal VFS codepaths; just take care of making
persistent in in mqueue_create_attr() and discardable in mqueue_unlink()
and it doesn't need kill_litter_super() at all.
mqueue_unlink() side is best handled by having it call simple_unlink()
rather than duplicating its guts...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Very much ramfs-like; dget()+d_instantiate() -> d_make_persistent()
(in two places) is all it takes.
NB: might make sense to turn its ->put_super() into ->kill_sb().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Entirely static tree populated by simple_fill_super(). Can use
kill_anon_super() as-is.
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
entirely static tree, populated by simple_fill_super(). Can switch
to kill_anon_super() without any other changes.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
These are guaranteed to be empty by the time they are shut down;
both are single-instance and there is an internal mount maintained
for as long as there is any contents.
Both have that internal mount pinned by every object in root.
In other words, kill_litter_super() boils down to kill_anon_super()
for those.
Reviewed-by: Joel Becker <jlbec@evilplan.org>
Acked-by: Paul Moore <paul@paul-moore> (LSM)
Acked-by: Andreas Hindborg <a.hindborg@kernel.org> (configfs)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and there's no need to remember those pointers anywhere - ->kill_sb()
no longer needs to bother since kill_anon_super() will take care of
them anyway and proc_pid_readdir() only wants the inumbers, which
we had in a couple of static variables all along.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Quite a bit is already done by infrastructure changes (simple_link(),
simple_unlink()) - all that is left is replacing d_instantiate() +
pinning dget() (in ->symlink() and ->mknod()) with d_make_persistent(),
and, in case of shmem, using simple_unlink() and simple_link() in
->unlink() and ->link() resp., instead of open-coding those there.
Since d_make_persistent() accepts (and hashes) unhashed ones, shmem
situation gets simpler - we no longer care whether ->lookup() has hashed
the sucker.
With that done, we don't need kill_litter_super() for these filesystems
anymore - by the umount time all remaining dentries will be marked
persistent and kill_litter_super() will boil down to call of
kill_anon_super().
The same goes for devtmpfs and rootfs - they are handled by
ramfs or by shmem, depending upon config.
NB: strictly speaking, both devtmpfs and rootfs ought to use
ramfs_kill_sb() if they end up using ramfs; that's a separate
story and the only impact of "just use kill_{litter,anon}_super()"
is that we fail to free their sb->s_fs_info... on reboot.
That's orthogonal to the changes in this series - kill_litter_super()
is identical to kill_anon_super() for those at this point.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Note that simple_unlink() et.al. are used by many filesystems; for now
they can not assume that persistency mark will have been set back
when the object got created. Once all conversions are done we'll
have them complain if called for something that had not been marked
persistent.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* d_make_persistent(dentry, inode) - bump refcount, mark persistent and
make hashed positive. Return value is a borrowed reference to dentry;
it can be used until something removes persistency (at the very least,
until the parent gets unlocked, but some filesystems may have stronger
exclusion).
* d_make_discardable() - remove persistency mark and drop reference.
d_make_persistent() is similar to combination of d_instantiate(), dget()
and setting flag. The only difference is that unlike d_instantiate()
it accepts hashed and unhashed negatives alike. It is always called in
strong locking environment (parent held exclusive, or, in some cases,
dentry coming from d_alloc_name()); if we ever start using it with parent
held only shared and dentry coming from d_alloc_parallel(), we'll need
to copy the in-lookup logics from __d_add().
d_make_discardable() is eqiuvalent to combination of removing flag and
dput(); since flag removal requires ->d_lock, there's no point trying
to avoid taking that for refcount decrement as fast_dput() does.
The slow path of dput() has been taken into a helper and reused in
d_make_discardable() instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Some filesystems use a kinda-sorta controlled dentry refcount leak to pin
dentries of created objects in dcache (and undo it when removing those).
Reference is grabbed and not released, but it's not actually _stored_
anywhere. That works, but it's hard to follow and verify; among other
things, we have no way to tell _which_ of the increments is intended
to be an unpaired one. Worse, on removal we need to decide whether
the reference had already been dropped, which can be non-trivial if
that removal is on umount and we need to figure out if this dentry is
pinned due to e.g. unlink() not done. Usually that is handled by using
kill_litter_super() as ->kill_sb(), but there are open-coded special
cases of the same (consider e.g. /proc/self).
Things get simpler if we introduce a new dentry flag (DCACHE_PERSISTENT)
marking those "leaked" dentries. Having it set claims responsibility
for +1 in refcount.
The end result this series is aiming for:
* get these unbalanced dget() and dput() replaced with new primitives that
would, in addition to adjusting refcount, set and clear persistency flag.
* instead of having kill_litter_super() mess with removing the remaining
"leaked" references (e.g. for all tmpfs files that hadn't been removed
prior to umount), have the regular shrink_dcache_for_umount() strip
DCACHE_PERSISTENT of all dentries, dropping the corresponding
reference if it had been set. After that kill_litter_super() becomes
an equivalent of kill_anon_super().
Doing that in a single step is not feasible - it would affect too many places
in too many filesystems. It has to be split into a series.
Here we
* introduce the new flag
* teach shrink_dcache_for_umount() to handle it (i.e. remove
and drop refcount on anything that survives to umount with that flag
still set)
* teach kill_litter_super() that anything with that flag does
*not* need to be unpinned.
Next commits will add primitives for maintaing that flag and convert the
common helpers to those. After that - a long series of per-filesystem
patches converting to those primitives.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
simple_recursive_removal(), but instead of victim dentry it takes
parent + name.
Used to be open-coded in fs/fuse/control.c, but there's no need to expose
the guts of that thing there and there are other potential users, so
let's lift it into libfs...
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
If we have LOCKDOWN_TRACEFS, the function bails out - *after*
having locked the parent directory and without bothering to
undo that. Just check it before tracefs_start_creating()...
Fixes: e24709454c "tracefs/eventfs: Add missing lockdown checks"
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fuse_ctl_remove_conn() used to decrement the link count of root
manually; that got subsumed by simple_recursive_removal(), but
in case when subdirectory creation has failed the latter won't
get called.
Just move the modification of parent's link count into
fuse_ctl_add_dentry() to keep the things simple. Allows to
get rid of the nlink argument as well...
Fixes: fcaac5b427 "fuse_ctl: use simple_recursive_removal()"
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Two reverts merged into one commit to handle a regression caused by a
wrong cleanup because the underlying implications were unclear.
-----BEGIN PGP SIGNATURE-----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=BbUf
-----END PGP SIGNATURE-----
Merge tag 'i2c-for-6.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c fix from Wolfram Sang:
"Two reverts merged into one commit to handle a regression caused by a
wrong cleanup because the underlying implications were unclear"
* tag 'i2c-for-6.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: muxes: pca954x: Fix broken reset-gpio usage
- Strip trailing padding bytes from modules.builtin.modinfo to fix error
during modules_install with certain versions of kmod
- Drop unused static inline function warning in .c files with clang from
W=1 to W=2
- Ensure kernel-doc.py invocations use the PYTHON3 make variable to
ensure user's choice of Python interpreter is always respected
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQR74yXHMTGczQHYypIdayaRccAalgUCaRABuwAKCRAdayaRccAa
lpyDAQCiCQkpyG1JU2uKOaDTItA7BzK6iuCuqoePk0um+rIUKwEAq8fYCJU7kDM2
N+uL8Gw03vryftPYMVcfdrO0WsCBwgM=
=D8C8
-----END PGP SIGNATURE-----
Merge tag 'kbuild-fixes-6.18-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux
Pull Kbuild fixes from Nathan Chancellor:
- Strip trailing padding bytes from modules.builtin.modinfo to fix
error during modules_install with certain versions of kmod
- Drop unused static inline function warning in .c files with clang
from W=1 to W=2
- Ensure kernel-doc.py invocations use the PYTHON3 make variable to
ensure user's choice of Python interpreter is always respected
* tag 'kbuild-fixes-6.18-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
kbuild: Let kernel-doc.py use PYTHON3 override
compiler_types: Move unused static inline functions warning to W=2
kbuild: Strip trailing padding bytes from modules.builtin.modinfo
