linux-kernel - [PATCH] eventfs: Process deletion of dentry more thoroughly

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231031144703.71eef3a0@gandalf.local.home>
Date:   Tue, 31 Oct 2023 14:47:03 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>,
        Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ajay Kaher <akaher@...are.com>
Subject: [PATCH] eventfs: Process deletion of dentry more thoroughly

From: "Steven Rostedt (Google)" <rostedt@...dmis.org>

Looking at how dentry is removed via the tracefs system, I found that
eventfs does not do everything that it did under tracefs. The tracefs
removal of a dentry calls simple_recursive_removal() that does a lot more
than a simple d_invalidate().

Have the same done on eventfs dentry:

 1. Set S_DEAD for directories
 2. Call clear_nlink() on the dentry inode
 3. Call any notifiers about the dentry removal

Cc: stable@...r.kernel.org
Fixes: 5bdcd5f5331a2 ("eventfs: Implement removal of meta data from eventfs")
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 fs/tracefs/event_inode.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 4d2da7480e5f..ab807edaf538 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -856,6 +856,7 @@ static void unhook_dentry(struct dentry **dentry, struct dentry **list)
 		*dentry = NULL;
 	}
 }
+
 /**
  * eventfs_remove_dir - remove eventfs dir or file from list
  * @ei: eventfs_inode to be removed.
@@ -868,6 +869,7 @@ void eventfs_remove_dir(struct eventfs_inode *ei)
 	LIST_HEAD(ei_del_list);
 	struct dentry *dentry_list = NULL;
 	struct dentry *dentry;
+	struct inode *inode;
 	int i;
 
 	if (!ei)
@@ -891,7 +893,28 @@ void eventfs_remove_dir(struct eventfs_inode *ei)
 		ptr = (unsigned long)dentry->d_fsdata & ~1UL;
 		dentry_list = (struct dentry *)ptr;
 		dentry->d_fsdata = NULL;
+
+		inode = dentry->d_inode;
+		inode_lock(inode);
+		if (d_is_dir(dentry))
+			inode->i_flags |= S_DEAD;
+		clear_nlink(inode);
+		inode_unlock(inode);
+
+		inode = dentry->d_parent->d_inode;
+		inode_lock(inode);
+
+		/* Remove its visibility */
 		d_invalidate(dentry);
+		if (d_is_dir(dentry))
+			fsnotify_rmdir(inode, dentry);
+		else
+			fsnotify_unlink(inode, dentry);
+
+		if (d_is_dir(dentry))
+			drop_nlink(inode);
+		inode_unlock(inode);
+
 		mutex_lock(&eventfs_mutex);
 		/* dentry should now have at least a single reference */
 		WARN_ONCE((int)d_count(dentry) < 1,
-- 
2.42.0