1 files changed, 95 insertions, 10 deletions

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 2ccc849a5bda..f0677ea0ec24 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -113,7 +113,14 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
 	 * determined by the parent directory.
 	 */
 	if (dentry->d_inode->i_mode & S_IFDIR) {
-		update_attr(&ei->attr, iattr);
+		/*
+		 * The events directory dentry is never freed, unless its
+		 * part of an instance that is deleted. It's attr is the
+		 * default for its child files and directories.
+		 * Do not update it. It's not used for its own mode or ownership
+		 */
+		if (!ei->is_events)
+			update_attr(&ei->attr, iattr);
 
 	} else {
 		name = dentry->d_name.name;
@@ -148,28 +155,93 @@ static const struct file_operations eventfs_file_operations = {
 	.release	= eventfs_release,
 };
 
+/* Return the evenfs_inode of the "events" directory */
+static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
+{
+	struct eventfs_inode *ei;
+
+	mutex_lock(&eventfs_mutex);
+	do {
+		/* The parent always has an ei, except for events itself */
+		ei = dentry->d_parent->d_fsdata;
+
+		/*
+		 * If the ei is being freed, the ownership of the children
+		 * doesn't matter.
+		 */
+		if (ei->is_freed) {
+			ei = NULL;
+			break;
+		}
+
+		dentry = ei->dentry;
+	} while (!ei->is_events);
+	mutex_unlock(&eventfs_mutex);
+
+	return ei;
+}
+
 static void update_inode_attr(struct dentry *dentry, struct inode *inode,
 			      struct eventfs_attr *attr, umode_t mode)
 {
-	if (!attr) {
-		inode->i_mode = mode;
+	struct eventfs_inode *events_ei = eventfs_find_events(dentry);
+
+	if (!events_ei)
+		return;
+
+	inode->i_mode = mode;
+	inode->i_uid = events_ei->attr.uid;
+	inode->i_gid = events_ei->attr.gid;
+
+	if (!attr)
 		return;
-	}
 
 	if (attr->mode & EVENTFS_SAVE_MODE)
 		inode->i_mode = attr->mode & EVENTFS_MODE_MASK;
-	else
-		inode->i_mode = mode;
 
 	if (attr->mode & EVENTFS_SAVE_UID)
 		inode->i_uid = attr->uid;
-	else
-		inode->i_uid = d_inode(dentry->d_parent)->i_uid;
 
 	if (attr->mode & EVENTFS_SAVE_GID)
 		inode->i_gid = attr->gid;
-	else
-		inode->i_gid = d_inode(dentry->d_parent)->i_gid;
+}
+
+static void update_gid(struct eventfs_inode *ei, kgid_t gid, int level)
+{
+	struct eventfs_inode *ei_child;
+
+	/* at most we have events/system/event */
+	if (WARN_ON_ONCE(level > 3))
+		return;
+
+	ei->attr.gid = gid;
+
+	if (ei->entry_attrs) {
+		for (int i = 0; i < ei->nr_entries; i++) {
+			ei->entry_attrs[i].gid = gid;
+		}
+	}
+
+	/*
+	 * Only eventfs_inode with dentries are updated, make sure
+	 * all eventfs_inodes are updated. If one of the children
+	 * do not have a dentry, this function must traverse it.
+	 */
+	list_for_each_entry_srcu(ei_child, &ei->children, list,
+				 srcu_read_lock_held(&eventfs_srcu)) {
+		if (!ei_child->dentry)
+			update_gid(ei_child, gid, level + 1);
+	}
+}
+
+void eventfs_update_gid(struct dentry *dentry, kgid_t gid)
+{
+	struct eventfs_inode *ei = dentry->d_fsdata;
+	int idx;
+
+	idx = srcu_read_lock(&eventfs_srcu);
+	update_gid(ei, gid, 0);
+	srcu_read_unlock(&eventfs_srcu, idx);
 }
 
 /**
@@ -860,6 +932,8 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 	struct eventfs_inode *ei;
 	struct tracefs_inode *ti;
 	struct inode *inode;
+	kuid_t uid;
+	kgid_t gid;
 
 	if (security_locked_down(LOCKDOWN_TRACEFS))
 		return NULL;
@@ -884,11 +958,20 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 	ei->dentry = dentry;
 	ei->entries = entries;
 	ei->nr_entries = size;
+	ei->is_events = 1;
 	ei->data = data;
 	ei->name = kstrdup_const(name, GFP_KERNEL);
 	if (!ei->name)
 		goto fail;
 
+	/* Save the ownership of this directory */
+	uid = d_inode(dentry->d_parent)->i_uid;
+	gid = d_inode(dentry->d_parent)->i_gid;
+
+	/* This is used as the default ownership of the files and directories */
+	ei->attr.uid = uid;
+	ei->attr.gid = gid;
+
 	INIT_LIST_HEAD(&ei->children);
 	INIT_LIST_HEAD(&ei->list);
 
@@ -897,6 +980,8 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 	ti->private = ei;
 
 	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+	inode->i_uid = uid;
+	inode->i_gid = gid;
 	inode->i_op = &eventfs_root_dir_inode_operations;
 	inode->i_fop = &eventfs_file_operations;