1 files changed, 209 insertions, 0 deletions
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
new file mode 100644
index 000000000..993375f0d
--- /dev/null
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * fs/inotify_user.c - inotify support for userspace
+ *
+ * Authors:
+ *	John McCutchan	<ttb@tentacle.dhs.org>
+ *	Robert Love	<rml@novell.com>
+ *
+ * Copyright (C) 2005 John McCutchan
+ * Copyright 2006 Hewlett-Packard Development Company, L.P.
+ *
+ * Copyright (C) 2009 Eric Paris <Red Hat Inc>
+ * inotify was largely rewriten to make use of the fsnotify infrastructure
+ */
+
+#include <linux/dcache.h> /* d_unlinked */
+#include <linux/fs.h> /* struct inode */
+#include <linux/fsnotify_backend.h>
+#include <linux/inotify.h>
+#include <linux/path.h> /* struct path */
+#include <linux/slab.h> /* kmem_* */
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/sched/user.h>
+#include <linux/sched/mm.h>
+
+#include "inotify.h"
+
+/*
+ * Check if 2 events contain the same information.
+ */
+static bool event_compare(struct fsnotify_event *old_fsn,
+			  struct fsnotify_event *new_fsn)
+{
+	struct inotify_event_info *old, *new;
+
+	old = INOTIFY_E(old_fsn);
+	new = INOTIFY_E(new_fsn);
+	if (old->mask & FS_IN_IGNORED)
+		return false;
+	if ((old->mask == new->mask) &&
+	    (old->wd == new->wd) &&
+	    (old->name_len == new->name_len) &&
+	    (!old->name_len || !strcmp(old->name, new->name)))
+		return true;
+	return false;
+}
+
+static int inotify_merge(struct fsnotify_group *group,
+			 struct fsnotify_event *event)
+{
+	struct list_head *list = &group->notification_list;
+	struct fsnotify_event *last_event;
+
+	last_event = list_entry(list->prev, struct fsnotify_event, list);
+	return event_compare(last_event, event);
+}
+
+int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
+			       struct inode *inode, struct inode *dir,
+			       const struct qstr *name, u32 cookie)
+{
+	struct inotify_inode_mark *i_mark;
+	struct inotify_event_info *event;
+	struct fsnotify_event *fsn_event;
+	struct fsnotify_group *group = inode_mark->group;
+	int ret;
+	int len = 0, wd;
+	int alloc_len = sizeof(struct inotify_event_info);
+	struct mem_cgroup *old_memcg;
+
+	if (name) {
+		len = name->len;
+		alloc_len += len + 1;
+	}
+
+	pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
+		 mask);
+
+	i_mark = container_of(inode_mark, struct inotify_inode_mark,
+			      fsn_mark);
+
+	/*
+	 * We can be racing with mark being detached. Don't report event with
+	 * invalid wd.
+	 */
+	wd = READ_ONCE(i_mark->wd);
+	if (wd == -1)
+		return 0;
+	/*
+	 * Whoever is interested in the event, pays for the allocation. Do not
+	 * trigger OOM killer in the target monitoring memcg as it may have
+	 * security repercussion.
+	 */
+	old_memcg = set_active_memcg(group->memcg);
+	event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
+	set_active_memcg(old_memcg);
+
+	if (unlikely(!event)) {
+		/*
+		 * Treat lost event due to ENOMEM the same way as queue
+		 * overflow to let userspace know event was lost.
+		 */
+		fsnotify_queue_overflow(group);
+		return -ENOMEM;
+	}
+
+	/*
+	 * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
+	 * for fanotify. inotify never reported IN_ISDIR with those events.
+	 * It looks like an oversight, but to avoid the risk of breaking
+	 * existing inotify programs, mask the flag out from those events.
+	 */
+	if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
+		mask &= ~IN_ISDIR;
+
+	fsn_event = &event->fse;
+	fsnotify_init_event(fsn_event);
+	event->mask = mask;
+	event->wd = wd;
+	event->sync_cookie = cookie;
+	event->name_len = len;
+	if (len)
+		strcpy(event->name, name->name);
+
+	ret = fsnotify_add_event(group, fsn_event, inotify_merge);
+	if (ret) {
+		/* Our event wasn't used in the end. Free it. */
+		fsnotify_destroy_event(group, fsn_event);
+	}
+
+	if (inode_mark->flags & FSNOTIFY_MARK_FLAG_IN_ONESHOT)
+		fsnotify_destroy_mark(inode_mark, group);
+
+	return 0;
+}
+
+static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
+{
+	inotify_ignored_and_remove_idr(fsn_mark, group);
+}
+
+/*
+ * This is NEVER supposed to be called.  Inotify marks should either have been
+ * removed from the idr when the watch was removed or in the
+ * fsnotify_destroy_mark_by_group() call when the inotify instance was being
+ * torn down.  This is only called if the idr is about to be freed but there
+ * are still marks in it.
+ */
+static int idr_callback(int id, void *p, void *data)
+{
+	struct fsnotify_mark *fsn_mark;
+	struct inotify_inode_mark *i_mark;
+	static bool warned = false;
+
+	if (warned)
+		return 0;
+
+	warned = true;
+	fsn_mark = p;
+	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
+
+	WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
+		"idr.  Probably leaking memory\n", id, p, data);
+
+	/*
+	 * I'm taking the liberty of assuming that the mark in question is a
+	 * valid address and I'm dereferencing it.  This might help to figure
+	 * out why we got here and the panic is no worse than the original
+	 * BUG() that was here.
+	 */
+	if (fsn_mark)
+		printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
+			fsn_mark->group, i_mark->wd);
+	return 0;
+}
+
+static void inotify_free_group_priv(struct fsnotify_group *group)
+{
+	/* ideally the idr is empty and we won't hit the BUG in the callback */
+	idr_for_each(&group->inotify_data.idr, idr_callback, group);
+	idr_destroy(&group->inotify_data.idr);
+	if (group->inotify_data.ucounts)
+		dec_inotify_instances(group->inotify_data.ucounts);
+}
+
+static void inotify_free_event(struct fsnotify_group *group,
+			       struct fsnotify_event *fsn_event)
+{
+	kfree(INOTIFY_E(fsn_event));
+}
+
+/* ding dong the mark is dead */
+static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
+{
+	struct inotify_inode_mark *i_mark;
+
+	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
+
+	kmem_cache_free(inotify_inode_mark_cachep, i_mark);
+}
+
+const struct fsnotify_ops inotify_fsnotify_ops = {
+	.handle_inode_event = inotify_handle_inode_event,
+	.free_group_priv = inotify_free_group_priv,
+	.free_event = inotify_free_event,
+	.freeing_mark = inotify_freeing_mark,
+	.free_mark = inotify_free_mark,
+};