linux/fs/notify/fanotify/fanotify.c
Eric Paris 3a9b16b407 fsnotify: send fsnotify_mark to groups in event handling functions
With the change of fsnotify to use srcu walking the marks list instead of
walking the global groups list we now know the mark in question.  The code can
send the mark to the group's handling functions and the groups won't have to
find those marks themselves.

Signed-off-by: Eric Paris <eparis@redhat.com>
2010-07-28 10:18:52 -04:00

247 lines
6.3 KiB
C

#include <linux/fanotify.h>
#include <linux/fdtable.h>
#include <linux/fsnotify_backend.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h> /* UINT_MAX */
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/wait.h>
static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
{
pr_debug("%s: old=%p new=%p\n", __func__, old, new);
if (old->to_tell == new->to_tell &&
old->data_type == new->data_type &&
old->tgid == new->tgid) {
switch (old->data_type) {
case (FSNOTIFY_EVENT_FILE):
if ((old->file->f_path.mnt == new->file->f_path.mnt) &&
(old->file->f_path.dentry == new->file->f_path.dentry))
return true;
case (FSNOTIFY_EVENT_NONE):
return true;
default:
BUG();
};
}
return false;
}
/* and the list better be locked by something too! */
static struct fsnotify_event *fanotify_merge(struct list_head *list,
struct fsnotify_event *event)
{
struct fsnotify_event_holder *test_holder;
struct fsnotify_event *test_event = NULL;
struct fsnotify_event *new_event;
pr_debug("%s: list=%p event=%p\n", __func__, list, event);
list_for_each_entry_reverse(test_holder, list, event_list) {
if (should_merge(test_holder->event, event)) {
test_event = test_holder->event;
break;
}
}
if (!test_event)
return NULL;
fsnotify_get_event(test_event);
/* if they are exactly the same we are done */
if (test_event->mask == event->mask)
return test_event;
/*
* if the refcnt == 2 this is the only queue
* for this event and so we can update the mask
* in place.
*/
if (atomic_read(&test_event->refcnt) == 2) {
test_event->mask |= event->mask;
return test_event;
}
new_event = fsnotify_clone_event(test_event);
/* done with test_event */
fsnotify_put_event(test_event);
/* couldn't allocate memory, merge was not possible */
if (unlikely(!new_event))
return ERR_PTR(-ENOMEM);
/* build new event and replace it on the list */
new_event->mask = (test_event->mask | event->mask);
fsnotify_replace_event(test_holder, new_event);
/* we hold a reference on new_event from clone_event */
return new_event;
}
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
static int fanotify_get_response_from_access(struct fsnotify_group *group,
struct fsnotify_event *event)
{
int ret;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
wait_event(group->fanotify_data.access_waitq, event->response);
/* userspace responded, convert to something usable */
spin_lock(&event->lock);
switch (event->response) {
case FAN_ALLOW:
ret = 0;
break;
case FAN_DENY:
default:
ret = -EPERM;
}
event->response = 0;
spin_unlock(&event->lock);
pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
group, event, ret);
return ret;
}
#endif
static int fanotify_handle_event(struct fsnotify_group *group,
struct fsnotify_mark *mark,
struct fsnotify_event *event)
{
int ret = 0;
struct fsnotify_event *notify_event = NULL;
BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
if (IS_ERR(notify_event))
return PTR_ERR(notify_event);
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
if (event->mask & FAN_ALL_PERM_EVENTS) {
/* if we merged we need to wait on the new event */
if (notify_event)
event = notify_event;
ret = fanotify_get_response_from_access(group, event);
}
#endif
if (notify_event)
fsnotify_put_event(notify_event);
return ret;
}
static bool should_send_vfsmount_event(struct fsnotify_group *group, struct vfsmount *mnt,
struct inode *inode, __u32 mask)
{
struct fsnotify_mark *mnt_mark;
struct fsnotify_mark *inode_mark;
pr_debug("%s: group=%p vfsmount=%p mask=%x\n",
__func__, group, mnt, mask);
mnt_mark = fsnotify_find_vfsmount_mark(group, mnt);
if (!mnt_mark)
return false;
mask &= mnt_mark->mask;
mask &= ~mnt_mark->ignored_mask;
if (mask) {
inode_mark = fsnotify_find_inode_mark(group, inode);
if (inode_mark) {
mask &= ~inode_mark->ignored_mask;
fsnotify_put_mark(inode_mark);
}
}
/* find took a reference */
fsnotify_put_mark(mnt_mark);
return mask;
}
static bool should_send_inode_event(struct fsnotify_group *group, struct inode *inode,
__u32 mask)
{
struct fsnotify_mark *fsn_mark;
pr_debug("%s: group=%p inode=%p mask=%x\n",
__func__, group, inode, mask);
fsn_mark = fsnotify_find_inode_mark(group, inode);
if (!fsn_mark)
return false;
/* if the event is for a child and this inode doesn't care about
* events on the child, don't send it! */
if ((mask & FS_EVENT_ON_CHILD) &&
!(fsn_mark->mask & FS_EVENT_ON_CHILD)) {
mask = 0;
} else {
/*
* We care about children, but do we care about this particular
* type of event?
*/
mask &= ~FS_EVENT_ON_CHILD;
mask &= fsn_mark->mask;
mask &= ~fsn_mark->ignored_mask;
}
/* find took a reference */
fsnotify_put_mark(fsn_mark);
return mask;
}
static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *to_tell,
struct vfsmount *mnt, struct fsnotify_mark *mark,
__u32 mask, void *data, int data_type)
{
pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n",
__func__, group, to_tell, mnt, mask, data, data_type);
/* sorry, fanotify only gives a damn about files and dirs */
if (!S_ISREG(to_tell->i_mode) &&
!S_ISDIR(to_tell->i_mode))
return false;
/* if we don't have enough info to send an event to userspace say no */
if (data_type != FSNOTIFY_EVENT_FILE)
return false;
if (mnt)
return should_send_vfsmount_event(group, mnt, to_tell, mask);
else
return should_send_inode_event(group, to_tell, mask);
}
const struct fsnotify_ops fanotify_fsnotify_ops = {
.handle_event = fanotify_handle_event,
.should_send_event = fanotify_should_send_event,
.free_group_priv = NULL,
.free_event_priv = NULL,
.freeing_mark = NULL,
};