tracefs: Update inode permissions on remount

When a remount happens, if a gid or uid is specified update the inodes to
have the same gid and uid. This will allow the simplification of the
permissions logic for the dynamically created files and directories.

Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.592429986@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Fixes: baa23a8d4360d ("tracefs: Reset permissions on remount if permissions are options")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 55a40a730b10c81fde0d25ed2a04ffd4ea80837e..5dfb1ccd56ea7369739a4147442f1b71a7730e4c 100644 (file)
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -317,20 +317,29 @@ void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid)
        if (!ei)
                return;
 
-       if (update_uid)
+       if (update_uid) {
                ei->attr.mode &= ~EVENTFS_SAVE_UID;
+               ei->attr.uid = ti->vfs_inode.i_uid;
+       }
+
 
-       if (update_gid)
+       if (update_gid) {
                ei->attr.mode &= ~EVENTFS_SAVE_GID;
+               ei->attr.gid = ti->vfs_inode.i_gid;
+       }
 
        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 = ti->vfs_inode.i_uid;
+               }
+               if (update_gid) {
                        ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_GID;
+                       ei->entry_attrs[i].gid = ti->vfs_inode.i_gid;
+               }
        }
 }
 

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index a827f6a716c44ec840357a3afee7a51c04296c86..9252e0d78ea225db3c4ac7ce54bda15392cbec86 100644 (file)
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -373,12 +373,21 @@ static int tracefs_apply_options(struct super_block *sb, bool remount)
 
                rcu_read_lock();
                list_for_each_entry_rcu(ti, &tracefs_inodes, list) {
-                       if (update_uid)
+                       if (update_uid) {
                                ti->flags &= ~TRACEFS_UID_PERM_SET;
+                               ti->vfs_inode.i_uid = fsi->uid;
+                       }
 
-                       if (update_gid)
+                       if (update_gid) {
                                ti->flags &= ~TRACEFS_GID_PERM_SET;
-
+                               ti->vfs_inode.i_gid = fsi->gid;
+                       }
+
+                       /*
+                        * Note, the above ti->vfs_inode updates are
+                        * used in eventfs_remount() so they must come
+                        * before calling it.
+                        */
                        if (ti->flags & TRACEFS_EVENT_INODE)
                                eventfs_remount(ti, update_uid, update_gid);
                }