1 files changed, 601 insertions, 0 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
new file mode 100644
index 000000000..7974e91ff
--- /dev/null
+++ b/fs/notify/fsnotify.c
@@ -0,0 +1,601 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
+ */
+
+#include <linux/dcache.h>
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/srcu.h>
+
+#include <linux/fsnotify_backend.h>
+#include "fsnotify.h"
+
+/*
+ * Clear all of the marks on an inode when it is being evicted from core
+ */
+void __fsnotify_inode_delete(struct inode *inode)
+{
+	fsnotify_clear_marks_by_inode(inode);
+}
+EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
+
+void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
+{
+	fsnotify_clear_marks_by_mount(mnt);
+}
+
+/**
+ * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
+ * @sb: superblock being unmounted.
+ *
+ * Called during unmount with no locks held, so needs to be safe against
+ * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
+ */
+static void fsnotify_unmount_inodes(struct super_block *sb)
+{
+	struct inode *inode, *iput_inode = NULL;
+
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+		/*
+		 * We cannot __iget() an inode in state I_FREEING,
+		 * I_WILL_FREE, or I_NEW which is fine because by that point
+		 * the inode cannot have any associated watches.
+		 */
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+
+		/*
+		 * If i_count is zero, the inode cannot have any watches and
+		 * doing an __iget/iput with SB_ACTIVE clear would actually
+		 * evict all inodes with zero i_count from icache which is
+		 * unnecessarily violent and may in fact be illegal to do.
+		 * However, we should have been called /after/ evict_inodes
+		 * removed all zero refcount inodes, in any case.  Test to
+		 * be sure.
+		 */
+		if (!atomic_read(&inode->i_count)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&sb->s_inode_list_lock);
+
+		iput(iput_inode);
+
+		/* for each watch, send FS_UNMOUNT and then remove it */
+		fsnotify_inode(inode, FS_UNMOUNT);
+
+		fsnotify_inode_delete(inode);
+
+		iput_inode = inode;
+
+		cond_resched();
+		spin_lock(&sb->s_inode_list_lock);
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+
+	iput(iput_inode);
+}
+
+void fsnotify_sb_delete(struct super_block *sb)
+{
+	fsnotify_unmount_inodes(sb);
+	fsnotify_clear_marks_by_sb(sb);
+	/* Wait for outstanding object references from connectors */
+	wait_var_event(&sb->s_fsnotify_connectors,
+		       !atomic_long_read(&sb->s_fsnotify_connectors));
+}
+
+/*
+ * Given an inode, first check if we care what happens to our children.  Inotify
+ * and dnotify both tell their parents about events.  If we care about any event
+ * on a child we run all of our children and set a dentry flag saying that the
+ * parent cares.  Thus when an event happens on a child it can quickly tell
+ * if there is a need to find a parent and send the event to the parent.
+ */
+void __fsnotify_update_child_dentry_flags(struct inode *inode)
+{
+	struct dentry *alias;
+	int watched;
+
+	if (!S_ISDIR(inode->i_mode))
+		return;
+
+	/* determine if the children should tell inode about their events */
+	watched = fsnotify_inode_watches_children(inode);
+
+	spin_lock(&inode->i_lock);
+	/* run all of the dentries associated with this inode.  Since this is a
+	 * directory, there damn well better only be one item on this list */
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
+		struct dentry *child;
+
+		/* run all of the children of the original inode and fix their
+		 * d_flags to indicate parental interest (their parent is the
+		 * original inode) */
+		spin_lock(&alias->d_lock);
+		list_for_each_entry(child, &alias->d_subdirs, d_child) {
+			if (!child->d_inode)
+				continue;
+
+			spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
+			if (watched)
+				child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+			else
+				child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
+			spin_unlock(&child->d_lock);
+		}
+		spin_unlock(&alias->d_lock);
+	}
+	spin_unlock(&inode->i_lock);
+}
+
+/* Are inode/sb/mount interested in parent and name info with this event? */
+static bool fsnotify_event_needs_parent(struct inode *inode, struct mount *mnt,
+					__u32 mask)
+{
+	__u32 marks_mask = 0;
+
+	/* We only send parent/name to inode/sb/mount for events on non-dir */
+	if (mask & FS_ISDIR)
+		return false;
+
+	/*
+	 * All events that are possible on child can also may be reported with
+	 * parent/name info to inode/sb/mount.  Otherwise, a watching parent
+	 * could result in events reported with unexpected name info to sb/mount.
+	 */
+	BUILD_BUG_ON(FS_EVENTS_POSS_ON_CHILD & ~FS_EVENTS_POSS_TO_PARENT);
+
+	/* Did either inode/sb/mount subscribe for events with parent/name? */
+	marks_mask |= fsnotify_parent_needed_mask(inode->i_fsnotify_mask);
+	marks_mask |= fsnotify_parent_needed_mask(inode->i_sb->s_fsnotify_mask);
+	if (mnt)
+		marks_mask |= fsnotify_parent_needed_mask(mnt->mnt_fsnotify_mask);
+
+	/* Did they subscribe for this event with parent/name info? */
+	return mask & marks_mask;
+}
+
+/*
+ * Notify this dentry's parent about a child's events with child name info
+ * if parent is watching or if inode/sb/mount are interested in events with
+ * parent and name info.
+ *
+ * Notify only the child without name info if parent is not watching and
+ * inode/sb/mount are not interested in events with parent and name info.
+ */
+int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
+		      int data_type)
+{
+	const struct path *path = fsnotify_data_path(data, data_type);
+	struct mount *mnt = path ? real_mount(path->mnt) : NULL;
+	struct inode *inode = d_inode(dentry);
+	struct dentry *parent;
+	bool parent_watched = dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED;
+	bool parent_needed, parent_interested;
+	__u32 p_mask;
+	struct inode *p_inode = NULL;
+	struct name_snapshot name;
+	struct qstr *file_name = NULL;
+	int ret = 0;
+
+	/*
+	 * Do inode/sb/mount care about parent and name info on non-dir?
+	 * Do they care about any event at all?
+	 */
+	if (!inode->i_fsnotify_marks && !inode->i_sb->s_fsnotify_marks &&
+	    (!mnt || !mnt->mnt_fsnotify_marks) && !parent_watched)
+		return 0;
+
+	parent = NULL;
+	parent_needed = fsnotify_event_needs_parent(inode, mnt, mask);
+	if (!parent_watched && !parent_needed)
+		goto notify;
+
+	/* Does parent inode care about events on children? */
+	parent = dget_parent(dentry);
+	p_inode = parent->d_inode;
+	p_mask = fsnotify_inode_watches_children(p_inode);
+	if (unlikely(parent_watched && !p_mask))
+		__fsnotify_update_child_dentry_flags(p_inode);
+
+	/*
+	 * Include parent/name in notification either if some notification
+	 * groups require parent info or the parent is interested in this event.
+	 */
+	parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS;
+	if (parent_needed || parent_interested) {
+		/* When notifying parent, child should be passed as data */
+		WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type));
+
+		/* Notify both parent and child with child name info */
+		take_dentry_name_snapshot(&name, dentry);
+		file_name = &name.name;
+		if (parent_interested)
+			mask |= FS_EVENT_ON_CHILD;
+	}
+
+notify:
+	ret = fsnotify(mask, data, data_type, p_inode, file_name, inode, 0);
+
+	if (file_name)
+		release_dentry_name_snapshot(&name);
+	dput(parent);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__fsnotify_parent);
+
+static int fsnotify_handle_inode_event(struct fsnotify_group *group,
+				       struct fsnotify_mark *inode_mark,
+				       u32 mask, const void *data, int data_type,
+				       struct inode *dir, const struct qstr *name,
+				       u32 cookie)
+{
+	const struct path *path = fsnotify_data_path(data, data_type);
+	struct inode *inode = fsnotify_data_inode(data, data_type);
+	const struct fsnotify_ops *ops = group->ops;
+
+	if (WARN_ON_ONCE(!ops->handle_inode_event))
+		return 0;
+
+	if (WARN_ON_ONCE(!inode && !dir))
+		return 0;
+
+	if ((inode_mark->flags & FSNOTIFY_MARK_FLAG_EXCL_UNLINK) &&
+	    path && d_unlinked(path->dentry))
+		return 0;
+
+	/* Check interest of this mark in case event was sent with two marks */
+	if (!(mask & inode_mark->mask & ALL_FSNOTIFY_EVENTS))
+		return 0;
+
+	return ops->handle_inode_event(inode_mark, mask, inode, dir, name, cookie);
+}
+
+static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
+				 const void *data, int data_type,
+				 struct inode *dir, const struct qstr *name,
+				 u32 cookie, struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
+	struct fsnotify_mark *parent_mark = fsnotify_iter_parent_mark(iter_info);
+	int ret;
+
+	if (WARN_ON_ONCE(fsnotify_iter_sb_mark(iter_info)) ||
+	    WARN_ON_ONCE(fsnotify_iter_vfsmount_mark(iter_info)))
+		return 0;
+
+	/*
+	 * For FS_RENAME, 'dir' is old dir and 'data' is new dentry.
+	 * The only ->handle_inode_event() backend that supports FS_RENAME is
+	 * dnotify, where it means file was renamed within same parent.
+	 */
+	if (mask & FS_RENAME) {
+		struct dentry *moved = fsnotify_data_dentry(data, data_type);
+
+		if (dir != moved->d_parent->d_inode)
+			return 0;
+	}
+
+	if (parent_mark) {
+		ret = fsnotify_handle_inode_event(group, parent_mark, mask,
+						  data, data_type, dir, name, 0);
+		if (ret)
+			return ret;
+	}
+
+	if (!inode_mark)
+		return 0;
+
+	if (mask & FS_EVENT_ON_CHILD) {
+		/*
+		 * Some events can be sent on both parent dir and child marks
+		 * (e.g. FS_ATTRIB).  If both parent dir and child are
+		 * watching, report the event once to parent dir with name (if
+		 * interested) and once to child without name (if interested).
+		 * The child watcher is expecting an event without a file name
+		 * and without the FS_EVENT_ON_CHILD flag.
+		 */
+		mask &= ~FS_EVENT_ON_CHILD;
+		dir = NULL;
+		name = NULL;
+	}
+
+	return fsnotify_handle_inode_event(group, inode_mark, mask, data, data_type,
+					   dir, name, cookie);
+}
+
+static int send_to_group(__u32 mask, const void *data, int data_type,
+			 struct inode *dir, const struct qstr *file_name,
+			 u32 cookie, struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_group *group = NULL;
+	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
+	__u32 marks_mask = 0;
+	__u32 marks_ignore_mask = 0;
+	bool is_dir = mask & FS_ISDIR;
+	struct fsnotify_mark *mark;
+	int type;
+
+	if (!iter_info->report_mask)
+		return 0;
+
+	/* clear ignored on inode modification */
+	if (mask & FS_MODIFY) {
+		fsnotify_foreach_iter_mark_type(iter_info, mark, type) {
+			if (!(mark->flags &
+			      FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
+				mark->ignore_mask = 0;
+		}
+	}
+
+	/* Are any of the group marks interested in this event? */
+	fsnotify_foreach_iter_mark_type(iter_info, mark, type) {
+		group = mark->group;
+		marks_mask |= mark->mask;
+		marks_ignore_mask |=
+			fsnotify_effective_ignore_mask(mark, is_dir, type);
+	}
+
+	pr_debug("%s: group=%p mask=%x marks_mask=%x marks_ignore_mask=%x data=%p data_type=%d dir=%p cookie=%d\n",
+		 __func__, group, mask, marks_mask, marks_ignore_mask,
+		 data, data_type, dir, cookie);
+
+	if (!(test_mask & marks_mask & ~marks_ignore_mask))
+		return 0;
+
+	if (group->ops->handle_event) {
+		return group->ops->handle_event(group, mask, data, data_type, dir,
+						file_name, cookie, iter_info);
+	}
+
+	return fsnotify_handle_event(group, mask, data, data_type, dir,
+				     file_name, cookie, iter_info);
+}
+
+static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)
+{
+	struct fsnotify_mark_connector *conn;
+	struct hlist_node *node = NULL;
+
+	conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
+	if (conn)
+		node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu);
+
+	return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
+}
+
+static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark)
+{
+	struct hlist_node *node = NULL;
+
+	if (mark)
+		node = srcu_dereference(mark->obj_list.next,
+					&fsnotify_mark_srcu);
+
+	return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
+}
+
+/*
+ * iter_info is a multi head priority queue of marks.
+ * Pick a subset of marks from queue heads, all with the same group
+ * and set the report_mask to a subset of the selected marks.
+ * Returns false if there are no more groups to iterate.
+ */
+static bool fsnotify_iter_select_report_types(
+		struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_group *max_prio_group = NULL;
+	struct fsnotify_mark *mark;
+	int type;
+
+	/* Choose max prio group among groups of all queue heads */
+	fsnotify_foreach_iter_type(type) {
+		mark = iter_info->marks[type];
+		if (mark &&
+		    fsnotify_compare_groups(max_prio_group, mark->group) > 0)
+			max_prio_group = mark->group;
+	}
+
+	if (!max_prio_group)
+		return false;
+
+	/* Set the report mask for marks from same group as max prio group */
+	iter_info->current_group = max_prio_group;
+	iter_info->report_mask = 0;
+	fsnotify_foreach_iter_type(type) {
+		mark = iter_info->marks[type];
+		if (mark && mark->group == iter_info->current_group) {
+			/*
+			 * FSNOTIFY_ITER_TYPE_PARENT indicates that this inode
+			 * is watching children and interested in this event,
+			 * which is an event possible on child.
+			 * But is *this mark* watching children?
+			 */
+			if (type == FSNOTIFY_ITER_TYPE_PARENT &&
+			    !(mark->mask & FS_EVENT_ON_CHILD) &&
+			    !(fsnotify_ignore_mask(mark) & FS_EVENT_ON_CHILD))
+				continue;
+
+			fsnotify_iter_set_report_type(iter_info, type);
+		}
+	}
+
+	return true;
+}
+
+/*
+ * Pop from iter_info multi head queue, the marks that belong to the group of
+ * current iteration step.
+ */
+static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_mark *mark;
+	int type;
+
+	/*
+	 * We cannot use fsnotify_foreach_iter_mark_type() here because we
+	 * may need to advance a mark of type X that belongs to current_group
+	 * but was not selected for reporting.
+	 */
+	fsnotify_foreach_iter_type(type) {
+		mark = iter_info->marks[type];
+		if (mark && mark->group == iter_info->current_group)
+			iter_info->marks[type] =
+				fsnotify_next_mark(iter_info->marks[type]);
+	}
+}
+
+/*
+ * fsnotify - This is the main call to fsnotify.
+ *
+ * The VFS calls into hook specific functions in linux/fsnotify.h.
+ * Those functions then in turn call here.  Here will call out to all of the
+ * registered fsnotify_group.  Those groups can then use the notification event
+ * in whatever means they feel necessary.
+ *
+ * @mask:	event type and flags
+ * @data:	object that event happened on
+ * @data_type:	type of object for fanotify_data_XXX() accessors
+ * @dir:	optional directory associated with event -
+ *		if @file_name is not NULL, this is the directory that
+ *		@file_name is relative to
+ * @file_name:	optional file name associated with event
+ * @inode:	optional inode associated with event -
+ *		If @dir and @inode are both non-NULL, event may be
+ *		reported to both.
+ * @cookie:	inotify rename cookie
+ */
+int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
+	     const struct qstr *file_name, struct inode *inode, u32 cookie)
+{
+	const struct path *path = fsnotify_data_path(data, data_type);
+	struct super_block *sb = fsnotify_data_sb(data, data_type);
+	struct fsnotify_iter_info iter_info = {};
+	struct mount *mnt = NULL;
+	struct inode *inode2 = NULL;
+	struct dentry *moved;
+	int inode2_type;
+	int ret = 0;
+	__u32 test_mask, marks_mask;
+
+	if (path)
+		mnt = real_mount(path->mnt);
+
+	if (!inode) {
+		/* Dirent event - report on TYPE_INODE to dir */
+		inode = dir;
+		/* For FS_RENAME, inode is old_dir and inode2 is new_dir */
+		if (mask & FS_RENAME) {
+			moved = fsnotify_data_dentry(data, data_type);
+			inode2 = moved->d_parent->d_inode;
+			inode2_type = FSNOTIFY_ITER_TYPE_INODE2;
+		}
+	} else if (mask & FS_EVENT_ON_CHILD) {
+		/*
+		 * Event on child - report on TYPE_PARENT to dir if it is
+		 * watching children and on TYPE_INODE to child.
+		 */
+		inode2 = dir;
+		inode2_type = FSNOTIFY_ITER_TYPE_PARENT;
+	}
+
+	/*
+	 * Optimization: srcu_read_lock() has a memory barrier which can
+	 * be expensive.  It protects walking the *_fsnotify_marks lists.
+	 * However, if we do not walk the lists, we do not have to do
+	 * SRCU because we have no references to any objects and do not
+	 * need SRCU to keep them "alive".
+	 */
+	if (!sb->s_fsnotify_marks &&
+	    (!mnt || !mnt->mnt_fsnotify_marks) &&
+	    (!inode || !inode->i_fsnotify_marks) &&
+	    (!inode2 || !inode2->i_fsnotify_marks))
+		return 0;
+
+	marks_mask = sb->s_fsnotify_mask;
+	if (mnt)
+		marks_mask |= mnt->mnt_fsnotify_mask;
+	if (inode)
+		marks_mask |= inode->i_fsnotify_mask;
+	if (inode2)
+		marks_mask |= inode2->i_fsnotify_mask;
+
+
+	/*
+	 * If this is a modify event we may need to clear some ignore masks.
+	 * In that case, the object with ignore masks will have the FS_MODIFY
+	 * event in its mask.
+	 * Otherwise, return if none of the marks care about this type of event.
+	 */
+	test_mask = (mask & ALL_FSNOTIFY_EVENTS);
+	if (!(test_mask & marks_mask))
+		return 0;
+
+	iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
+
+	iter_info.marks[FSNOTIFY_ITER_TYPE_SB] =
+		fsnotify_first_mark(&sb->s_fsnotify_marks);
+	if (mnt) {
+		iter_info.marks[FSNOTIFY_ITER_TYPE_VFSMOUNT] =
+			fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
+	}
+	if (inode) {
+		iter_info.marks[FSNOTIFY_ITER_TYPE_INODE] =
+			fsnotify_first_mark(&inode->i_fsnotify_marks);
+	}
+	if (inode2) {
+		iter_info.marks[inode2_type] =
+			fsnotify_first_mark(&inode2->i_fsnotify_marks);
+	}
+
+	/*
+	 * We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark
+	 * ignore masks are properly reflected for mount/sb mark notifications.
+	 * That's why this traversal is so complicated...
+	 */
+	while (fsnotify_iter_select_report_types(&iter_info)) {
+		ret = send_to_group(mask, data, data_type, dir, file_name,
+				    cookie, &iter_info);
+
+		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
+			goto out;
+
+		fsnotify_iter_next(&iter_info);
+	}
+	ret = 0;
+out:
+	srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(fsnotify);
+
+static __init int fsnotify_init(void)
+{
+	int ret;
+
+	BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 23);
+
+	ret = init_srcu_struct(&fsnotify_mark_srcu);
+	if (ret)
+		panic("initializing fsnotify_mark_srcu");
+
+	fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector,
+						    SLAB_PANIC);
+
+	return 0;
+}
+core_initcall(fsnotify_init);