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 000000000000..eb8f73c9c131
--- /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,
+};