This is a note to let you know that I've just added the patch titled
eventfs: Update all the eventfs_inodes from the events descriptor
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
eventfs-update-all-the-eventfs_inodes-from-the-event.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d2f51b24d9c1f23a52d5b1b8047c10fb347a8789
Author: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Date: Thu May 23 01:14:28 2024 -0400
eventfs: Update all the eventfs_inodes from the events descriptor
[ Upstream commit 340f0c7067a95281ad13734f8225f49c6cf52067 ]
The change to update the permissions of the eventfs_inode had the
misconception that using the tracefs_inode would find all the
eventfs_inodes that have been updated and reset them on remount.
The problem with this approach is that the eventfs_inodes are freed when
they are no longer used (basically the reason the eventfs system exists).
When they are freed, the updated eventfs_inodes are not reset on a remount
because their tracefs_inodes have been freed.
Instead, since the events directory eventfs_inode always has a
tracefs_inode pointing to it (it is not freed when finished), and the
events directory has a link to all its children, have the
eventfs_remount() function only operate on the events eventfs_inode and
have it descend into its children updating their uid and gids.
Link: https://lore.kernel.org/all/CAK7LNARXgaWw3kH9JgrnH4vK6fr8LDkNKf3wq8NhMWJrVwJyVQ@xxxxxxxxxxxxxx/
Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.754424703@xxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Fixes: baa23a8d4360d ("tracefs: Reset permissions on remount if permissions are options")
Reported-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 55a40a730b10c..129d0f54ba62f 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -305,33 +305,60 @@ 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)
+static void eventfs_set_attrs(struct eventfs_inode *ei, bool update_uid, kuid_t uid,
+ bool update_gid, kgid_t gid, int level)
{
- struct eventfs_inode *ei = ti->private;
+ struct eventfs_inode *ei_child;
- if (!ei)
+ /* Update events/<system>/<event> */
+ if (WARN_ON_ONCE(level > 3))
return;
- if (update_uid)
+ if (update_uid) {
ei->attr.mode &= ~EVENTFS_SAVE_UID;
+ ei->attr.uid = uid;
+ }
- if (update_gid)
+ if (update_gid) {
ei->attr.mode &= ~EVENTFS_SAVE_GID;
+ ei->attr.gid = gid;
+ }
+
+ list_for_each_entry(ei_child, &ei->children, list) {
+ eventfs_set_attrs(ei_child, update_uid, uid, update_gid, gid, level + 1);
+ }
if (!ei->entry_attrs)
return;
for (int i = 0; i < ei->nr_entries; i++) {
- if (update_uid)
+ if (update_uid) {
ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_UID;
- if (update_gid)
+ ei->entry_attrs[i].uid = uid;
+ }
+ if (update_gid) {
ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_GID;
+ ei->entry_attrs[i].gid = gid;
+ }
}
+
+}
+
+/*
+ * 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;
+
+ /* Only the events directory does the updates */
+ if (!ei || !ei->is_events || ei->is_freed)
+ return;
+
+ eventfs_set_attrs(ei, update_uid, ti->vfs_inode.i_uid,
+ update_gid, ti->vfs_inode.i_gid, 0);
}
/* Return the evenfs_inode of the "events" directory */
