1 files changed, 100 insertions, 55 deletions

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 894c6ca1e50020..0256afdd4acfb5 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -37,6 +37,7 @@ static DEFINE_MUTEX(eventfs_mutex);
 
 struct eventfs_root_inode {
 	struct eventfs_inode		ei;
+	struct inode			*parent_inode;
 	struct dentry			*events_dir;
 };
 
@@ -68,11 +69,25 @@ enum {
 	EVENTFS_SAVE_MODE	= BIT(16),
 	EVENTFS_SAVE_UID	= BIT(17),
 	EVENTFS_SAVE_GID	= BIT(18),
-	EVENTFS_TOPLEVEL	= BIT(19),
 };
 
 #define EVENTFS_MODE_MASK	(EVENTFS_SAVE_MODE - 1)
 
+static void free_ei_rcu(struct rcu_head *rcu)
+{
+	struct eventfs_inode *ei = container_of(rcu, struct eventfs_inode, rcu);
+	struct eventfs_root_inode *rei;
+
+	kfree(ei->entry_attrs);
+	kfree_const(ei->name);
+	if (ei->is_events) {
+		rei = get_root_inode(ei);
+		kfree(rei);
+	} else {
+		kfree(ei);
+	}
+}
+
 /*
  * eventfs_inode reference count management.
  *
@@ -84,18 +99,17 @@ enum {
 static void release_ei(struct kref *ref)
 {
 	struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref);
-	struct eventfs_root_inode *rei;
+	const struct eventfs_entry *entry;
 
 	WARN_ON_ONCE(!ei->is_freed);
 
-	kfree(ei->entry_attrs);
-	kfree_const(ei->name);
-	if (ei->is_events) {
-		rei = get_root_inode(ei);
-		kfree_rcu(rei, ei.rcu);
-	} else {
-		kfree_rcu(ei, rcu);
+	for (int i = 0; i < ei->nr_entries; i++) {
+		entry = &ei->entries[i];
+		if (entry->release)
+			entry->release(entry->name, ei->data);
 	}
+
+	call_rcu(&ei->rcu, free_ei_rcu);
 }
 
 static inline void put_ei(struct eventfs_inode *ei)
@@ -112,6 +126,18 @@ static inline void free_ei(struct eventfs_inode *ei)
 	}
 }
 
+/*
+ * Called when creation of an ei fails, do not call release() functions.
+ */
+static inline void cleanup_ei(struct eventfs_inode *ei)
+{
+	if (ei) {
+		/* Set nr_entries to 0 to prevent release() function being called */
+		ei->nr_entries = 0;
+		free_ei(ei);
+	}
+}
+
 static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei)
 {
 	if (ei)
@@ -181,21 +207,7 @@ 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) {
-		/*
-		 * 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) {
-			/* But it still needs to know if it was modified */
-			if (iattr->ia_valid & ATTR_UID)
-				ei->attr.mode |= EVENTFS_SAVE_UID;
-			if (iattr->ia_valid & ATTR_GID)
-				ei->attr.mode |= EVENTFS_SAVE_GID;
-		} else {
-			update_attr(&ei->attr, iattr);
-		}
+		update_attr(&ei->attr, iattr);
 
 	} else {
 		name = dentry->d_name.name;
@@ -213,18 +225,25 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
 	return ret;
 }
 
-static void update_top_events_attr(struct eventfs_inode *ei, struct super_block *sb)
+static void update_events_attr(struct eventfs_inode *ei, struct super_block *sb)
 {
-	struct inode *root;
+	struct eventfs_root_inode *rei;
+	struct inode *parent;
 
-	/* Only update if the "events" was on the top level */
-	if (!ei || !(ei->attr.mode & EVENTFS_TOPLEVEL))
-		return;
+	rei = get_root_inode(ei);
+
+	/* Use the parent inode permissions unless root set its permissions */
+	parent = rei->parent_inode;
+
+	if (rei->ei.attr.mode & EVENTFS_SAVE_UID)
+		ei->attr.uid = rei->ei.attr.uid;
+	else
+		ei->attr.uid = parent->i_uid;
 
-	/* Get the tracefs root inode. */
-	root = d_inode(sb->s_root);
-	ei->attr.uid = root->i_uid;
-	ei->attr.gid = root->i_gid;
+	if (rei->ei.attr.mode & EVENTFS_SAVE_GID)
+		ei->attr.gid = rei->ei.attr.gid;
+	else
+		ei->attr.gid = parent->i_gid;
 }
 
 static void set_top_events_ownership(struct inode *inode)
@@ -233,10 +252,10 @@ static void set_top_events_ownership(struct inode *inode)
 	struct eventfs_inode *ei = ti->private;
 
 	/* The top events directory doesn't get automatically updated */
-	if (!ei || !ei->is_events || !(ei->attr.mode & EVENTFS_TOPLEVEL))
+	if (!ei || !ei->is_events)
 		return;
 
-	update_top_events_attr(ei, inode->i_sb);
+	update_events_attr(ei, inode->i_sb);
 
 	if (!(ei->attr.mode & EVENTFS_SAVE_UID))
 		inode->i_uid = ei->attr.uid;
@@ -265,7 +284,7 @@ static int eventfs_permission(struct mnt_idmap *idmap,
 	return generic_permission(idmap, inode, mask);
 }
 
-static const struct inode_operations eventfs_root_dir_inode_operations = {
+static const struct inode_operations eventfs_dir_inode_operations = {
 	.lookup		= eventfs_root_lookup,
 	.setattr	= eventfs_set_attr,
 	.getattr	= eventfs_get_attr,
@@ -282,6 +301,35 @@ static const struct file_operations eventfs_file_operations = {
 	.llseek		= generic_file_llseek,
 };
 
+/*
+ * On a remount of tracefs, if UID or GID options are set, then
+ * the mount point inode permissions should be used.
+ * Reset the saved permission flags appropriately.
+ */
+void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid)
+{
+	struct eventfs_inode *ei = ti->private;
+
+	if (!ei)
+		return;
+
+	if (update_uid)
+		ei->attr.mode &= ~EVENTFS_SAVE_UID;
+
+	if (update_gid)
+		ei->attr.mode &= ~EVENTFS_SAVE_GID;
+
+	if (!ei->entry_attrs)
+		return;
+
+	for (int i = 0; i < ei->nr_entries; i++) {
+		if (update_uid)
+			ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_UID;
+		if (update_gid)
+			ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_GID;
+	}
+}
+
 /* Return the evenfs_inode of the "events" directory */
 static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
 {
@@ -297,14 +345,13 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
 		 * If the ei is being freed, the ownership of the children
 		 * doesn't matter.
 		 */
-		if (ei->is_freed) {
-			ei = NULL;
-			break;
-		}
+		if (ei->is_freed)
+			return NULL;
+
 		// Walk upwards until you find the events inode
 	} while (!ei->is_events);
 
-	update_top_events_attr(ei, dentry->d_sb);
+	update_events_attr(ei, dentry->d_sb);
 
 	return ei;
 }
@@ -410,7 +457,7 @@ static struct dentry *lookup_dir_entry(struct dentry *dentry,
 	update_inode_attr(dentry, inode, &ei->attr,
 			  S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO);
 
-	inode->i_op = &eventfs_root_dir_inode_operations;
+	inode->i_op = &eventfs_dir_inode_operations;
 	inode->i_fop = &eventfs_file_operations;
 
 	/* All directories will have the same inode number */
@@ -734,7 +781,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
 
 	/* Was the parent freed? */
 	if (list_empty(&ei->list)) {
-		free_ei(ei);
+		cleanup_ei(ei);
 		ei = NULL;
 	}
 	return ei;
@@ -781,6 +828,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 	// Note: we have a ref to the dentry from tracefs_start_creating()
 	rei = get_root_inode(ei);
 	rei->events_dir = dentry;
+	rei->parent_inode = d_inode(dentry->d_sb->s_root);
 
 	ei->entries = entries;
 	ei->nr_entries = size;
@@ -790,29 +838,26 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 	uid = d_inode(dentry->d_parent)->i_uid;
 	gid = d_inode(dentry->d_parent)->i_gid;
 
-	/*
-	 * If the events directory is of the top instance, then parent
-	 * is NULL. Set the attr.mode to reflect this and its permissions will
-	 * default to the tracefs root dentry.
-	 */
-	if (!parent)
-		ei->attr.mode = EVENTFS_TOPLEVEL;
-
-	/* This is used as the default ownership of the files and directories */
 	ei->attr.uid = uid;
 	ei->attr.gid = gid;
 
+	/*
+	 * When the "events" directory is created, it takes on the
+	 * permissions of its parent. But can be reset on remount.
+	 */
+	ei->attr.mode |= EVENTFS_SAVE_UID | EVENTFS_SAVE_GID;
+
 	INIT_LIST_HEAD(&ei->children);
 	INIT_LIST_HEAD(&ei->list);
 
 	ti = get_tracefs(inode);
-	ti->flags |= TRACEFS_EVENT_INODE | TRACEFS_EVENT_TOP_INODE;
+	ti->flags |= TRACEFS_EVENT_INODE;
 	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_op = &eventfs_dir_inode_operations;
 	inode->i_fop = &eventfs_file_operations;
 
 	dentry->d_fsdata = get_ei(ei);
@@ -835,7 +880,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 	return ei;
 
  fail:
-	free_ei(ei);
+	cleanup_ei(ei);
 	tracefs_failed_creating(dentry);
 	return ERR_PTR(-ENOMEM);
 }