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fanotify almost works like so:
user context calls fsnotify_* function with a struct file.
fsnotify takes a reference on the struct path
user context goes about it's buissiness
at some later point in time the fsnotify listener gets the struct path
fanotify listener calls dentry_open() to create a file which userspace can deal with
listener drops the reference on the struct path
at some later point the listener calls close() on it's new file
With the switch from struct path to struct file this presents a problem for
fput() and fsnotify_close(). fsnotify_close() is called when the filp has
already reached 0 and __fput() wants to do it's cleanup.
The solution presented here is a bit odd. If an event is created from a
struct file we take a reference on the file. We check however if the f_count
was already 0 and if so we take an EXTRA reference EVEN THOUGH IT WAS ZERO.
In __fput() (where we know the f_count hit 0 once) we check if the f_count is
non-zero and if so we drop that 'extra' ref and return without destroying the
file.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Al explains that calling dentry_open() with a mnt/dentry pair is only
garunteed to be safe if they are already used in an open struct file. To
make sure this is the case don't store and use a struct path in fsnotify,
always use a struct file.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Rather than the horrific void ** argument and such just to pass the
fanotify_merge event back to the caller of fsnotify_add_notify_event() have
those things return an event if it was different than the event suggusted to
be added.
Signed-off-by: Eric Paris <eparis@redhat.com>
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It can be hard to debug fsnotify since there are so few printks. Use
pr_debug to allow for dynamic debugging.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Currently fanotify fds opened for thier listeners are done with f_flags
equal to O_RDONLY | O_LARGEFILE. This patch instead takes f_flags from the
fanotify_init syscall and uses those when opening files in the context of
the listener.
Signed-off-by: Eric Paris <eparis@redhat.com>
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This patch adds a check to make sure that all fsnotify bits are unique and we
cannot accidentally use the same bit for 2 different fsnotify event types.
Signed-off-by: Eric Paris <eparis@redhat.com>
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The mask checks in inotify_update_existing_watch() and
inotify_new_watch() are useless because inotify_arg_to_mask() sets
FS_IN_IGNORED and FS_EVENT_ON_CHILD bits anyway.
Signed-off-by: Eric Paris <eparis@redhat.com>
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inotify uses bits called IN_* and fsnotify uses bits called FS_*. These
need to line up. This patch adds build time checks to make sure noone can
change these bits so they are not the same.
Signed-off-by: Eric Paris <eparis@redhat.com>
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An inotify watch on a directory will send events for children even if those
children have been unlinked. This patch add a new inotify flag IN_EXCL_UNLINK
which allows a watch to specificy they don't care about unlinked children.
This should fix performance problems seen by tasks which add a watch to
/tmp and then are overrun with events when other processes are reading and
writing to unlinked files they created in /tmp.
https://bugzilla.kernel.org/show_bug.cgi?id=16296
Requested-by: Matthias Clasen <mclasen@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Since the .31 or so notify rewrite inotify has not sent events about
inodes which are unmounted. This patch restores those events.
Signed-off-by: Eric Paris <eparis@redhat.com>
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During the large inotify rewrite to fsnotify I completely dropped support
for IN_ONESHOT. Reimplement that support.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Implicit slab.h inclusion via percpu.h is about to go away. Make sure
gfp.h or slab.h is included as necessary.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
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The priority argument in fanotify is useless. Kill it.
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify has default to y in linux-next since it's inception but default to
n in the final push to Linus.
Signed-off-by: Eric Paris <eparis@redhat.com>
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The symbol inotify_max_user_watches is not used outside this
file and should be static.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Eric Paris <eparis@redhat.com>
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akpm got a warning the fsnotify_mask could be used uninitialized in
fsnotify_perm(). It's not actually possible but his compiler complained
about it. This patch just initializes it to 0 to shut up the compiler.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>
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fsnotify takes an igrab on an inode when it adds a mark. The code was
supposed to drop the reference when the mark was removed but didn't.
This caused problems when an fs was unmounted because those inodes would
clearly not be gone. Thus resulting in the most devistating of messages:
VFS: Busy inodes after unmount of loop0. Self-destruct in 5 seconds.
>>> Have a nice day...
Jiri Slaby bisected the problem to a patch in the fsnotify tree. The
code snippets below show my stupidity quite clearly.
void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
{
...
mark->inode = NULL;
...
}
void fsnotify_destroy_mark(struct fsnotify_mark *mark)
{
struct inode *inode = NULL;
...
if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
fsnotify_destroy_inode_mark(mark);
inode = mark->i.inode;
}
...
if (inode)
iput(inode);
...
}
Obviously the intent was to capture the inode before it was set to NULL in
fsnotify_destory_inode_mark() so we wouldn't be leaking inodes forever.
Instead we leaked them (and exploded on umount)
Reported-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
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It seems to me you are always returning 0 in fsnotify, when you should return
the error (EPERM) returned by fanotify.
Signed-off-by: Jean-Christophe DUBOIS <jcd@tribudubois.net>
Signed-off-by: Eric Paris <eparis@redhat.com>
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remove_access_response() is supposed to have a void return, but was
returning 0;
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify groups need to respond to events which include permissions types.
To do so groups will send a response using write() on the fanotify_fd they
have open.
Signed-off-by: Eric Paris <eparis@redhat.com>
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This is the backend work needed for fanotify to support the new
FS_OPEN_PERM and FS_ACCESS_PERM fsnotify events. This is done using the
new fsnotify secondary queue. No userspace interface is provided actually
respond to or request these events.
Signed-off-by: Eric Paris <eparis@redhat.com>
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introduce a new fsnotify hook, fsnotify_perm(), which is called from the
security code. This hook is used to allow fsnotify groups to make access
control decisions about events on the system. We also must change the
generic fsnotify function to return an error code if we intend these hooks
to be in any way useful.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Extern declarations in sysctl.c should be move to their own head file, and
then include them in relavant .c files.
Move inotify_table extern declaration to linux/inotify.h
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Move dir_notify_enable declaration to where it belongs -- dnotify.h .
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
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fsnotify was using char * when it passed around the d_name.name string
internally but it is actually an unsigned char *. This patch switches
fsnotify to use unsigned and should silence some pointer signess warnings
which have popped out of xfs. I do not add -Wpointer-sign to the fsnotify
code as there are still issues with kstrdup and strlen which would pop
out needless warnings.
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify needs to know the actual event added to queues so it can be
correctly checked for return values from userspace. To do this we need to
pass that information from the merger code back to the main even handling
routine. Currently that information is unused, but it will be.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Each group can define their own notification (and secondary_q) merge
function. Inotify does tail drop, fanotify does matching and drop which
can actually allocate a completely new event. But for fanotify to properly
deal with permissions events it needs to know the new event which was
ultimately added to the notification queue. This patch just implements a
void ** argument which is passed to the merge function. fanotify can use
this field to pass the new event back to higher layers.
Signed-off-by: Eric Paris <eparis@redhat.com>
for fanotify to properly deal with permissions events
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This introduces an ordering to fsnotify groups. With purely asynchronous
notification based "things" implementing fsnotify (inotify, dnotify) ordering
isn't particularly important. But if people want to use fsnotify for the
basis of sycronous notification or blocking notification ordering becomes
important.
eg. A Hierarchical Storage Management listener would need to get its event
before an AV scanner could get its event (since the HSM would need to
bring the data in for the AV scanner to scan.) Typically asynchronous notification
would want to run after the AV scanner made any relevant access decisions
so as to not send notification about an event that was denied.
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify listeners may want to clear all marks. They may want to do this
to destroy all of their inode marks which have nothing but ignores.
Realistically this is useful for av vendors who update policy and want to
clear all of their cached allows.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Some users may want to truely ignore an inode even if it has been modified.
Say you are wanting a mount which contains a log file and you really don't
want any notification about that file. This patch allows the listener to
do that.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Some inodes a group may want to never hear about a set of events even if
the inode is modified. We add a new mark flag which indicates that these
marks should not have their ignored_mask cleared on modification.
Signed-off-by: Eric Paris <eparis@redhat.com>
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On inode modification we clear the ignored mask for all of the marks on the
inode. This allows userspace to ignore accesses to inodes until there is
something different.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Change the sys_fanotify_mark() system call so users can set ignored_masks
on inodes. Remember, if a user new sets a real mask, and only sets ignored
masks, the ignore will never be pinned in memory. Thus ignored_masks can
be lost under memory pressure and the user may again get events they
previously thought were ignored.
Signed-off-by: Eric Paris <eparis@redhat.com>
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When fanotify receives an event it will check event->mask & ~ignored_mask.
If no bits are left the event will not be sent.
Signed-off-by: Eric Paris <eparis@redhat.com>
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The ignored_mask is a new mask which is part of fsnotify marks. A group's
should_send_event() function can use the ignored mask to determine that
certain events are not of interest. In particular if a group registers a
mask including FS_OPEN on a vfsmount they could add FS_OPEN to the
ignored_mask for individual inodes and not send open events for those
inodes.
Signed-off-by: Eric Paris <eparis@redhat.com>
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inotify marks must pin inodes in core. dnotify doesn't technically need to
since they are closed when the directory is closed. fanotify also need to
pin inodes in core as it works today. But the next step is to introduce
the concept of 'ignored masks' which is actually a mask of events for an
inode of no interest. I claim that these should be liberally sent to the
kernel and should not pin the inode in core. If the inode is brought back
in the listener will get an event it may have thought excluded, but this is
not a serious situation and one any listener should deal with.
This patch lays the ground work for non-pinning inode marks by using lazy
inode pinning. We do not pin a mark until it has a non-zero mask entry. If a
listener new sets a mask we never pin the inode.
Signed-off-by: Eric Paris <eparis@redhat.com>
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A number of validity checks on outgoing data are done in static inlines but
are only used in one place. Instead just do them where they are used for
readability.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify_mark_validate functions are all needlessly declared in headers as
static inlines. Instead just do the checks where they are needed for code
readability.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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split fanotify_remove_mark into fanotify_remove_inode_mark and
fanotify_remove_vfsmount_mark.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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the term 'vfsmount' isn't sensicle to userspace. instead call is 'mount.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Create a new fanotify_mark flag which indicates we should attach the mark
to the vfsmount holding the object referenced by dfd and pathname rather
than the inode itself.
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify_add_mark now does nothing useful anymore, drop it.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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No need to return the mark from fanotify_add_*_mark to fanotify_add_mark
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Recalculate masks in fanotify_add_mark, don't use
fanotify_update_object_mask. This gets us one step closers to readable
code.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Recalculate masks in fanotify_remove_mark, don't use
fanotify_update_object_mask. This gets us one step closers to readable
code.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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fanotify_update_mark() doesn't do much useful; remove it.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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infrastructure work to add and remove marks on vfsmounts. This should get
every set up except wiring the functions to the syscalls.
Signed-off-by: Eric Paris <eparis@redhat.com>
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currently should_send_event in fanotify only cares about marks on inodes.
This patch extends that interface to indicate that it cares about events
that happened on vfsmounts.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Per-mount watches allow groups to listen to fsnotify events on an entire
mount. This patch simply adds and initializes the fields needed in the
vfsmount struct to make this happen.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Much like inode-mark.c has all of the code dealing with marks on inodes
this patch adds a vfsmount-mark.c which has similar code but is intended
for marks on vfsmounts.
Signed-off-by: Eric Paris <eparis@redhat.com>
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