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-rw-r--r--fs/notify/fanotify/fanotify.c212
1 files changed, 212 insertions, 0 deletions
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
new file mode 100644
index 0000000..eb8f73c
--- /dev/null
+++ b/fs/notify/fanotify/fanotify.c
@@ -0,0 +1,212 @@
+#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 *inode_mark,
+ struct fsnotify_mark *fanotify_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 fanotify_should_send_event(struct fsnotify_group *group,
+ struct inode *to_tell,
+ struct fsnotify_mark *inode_mark,
+ struct fsnotify_mark *vfsmnt_mark,
+ __u32 event_mask, void *data, int data_type)
+{
+ __u32 marks_mask, marks_ignored_mask;
+
+ pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p "
+ "mask=%x data=%p data_type=%d\n", __func__, group, to_tell,
+ inode_mark, vfsmnt_mark, event_mask, data, data_type);
+
+ pr_debug("%s: group=%p vfsmount_mark=%p inode_mark=%p mask=%x\n",
+ __func__, group, vfsmnt_mark, inode_mark, event_mask);
+
+ /* 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 (inode_mark && vfsmnt_mark) {
+ marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
+ marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
+ } else if (inode_mark) {
+ /*
+ * if the event is for a child and this inode doesn't care about
+ * events on the child, don't send it!
+ */
+ if ((event_mask & FS_EVENT_ON_CHILD) &&
+ !(inode_mark->mask & FS_EVENT_ON_CHILD))
+ return false;
+ marks_mask = inode_mark->mask;
+ marks_ignored_mask = inode_mark->ignored_mask;
+ } else if (vfsmnt_mark) {
+ marks_mask = vfsmnt_mark->mask;
+ marks_ignored_mask = vfsmnt_mark->ignored_mask;
+ } else {
+ BUG();
+ }
+
+ if (event_mask & marks_mask & ~marks_ignored_mask)
+ return true;
+
+ return false;
+}
+
+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,
+};
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