tracefs: Have new files inherit the ownership of their parent

If directories in tracefs have their ownership changed, then any new files
and directories that are created under those directories should inherit
the ownership of the director they are created in.

Link: https://lkml.kernel.org/r/20211208075720.4855d180@gandalf.local.home
Cc: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Yabin Cui <yabinc@google.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: stable@vger.kernel.org
Fixes: 4282d60689d4f ("tracefs: Add new tracefs file system")
Reported-by: Kalesh Singh <kaleshsingh@google.com>
Reported: https://lore.kernel.org/all/CAC_TJve8MMAv+H_NdLSJXZUSoxOEq2zB_pVaJ9p=7H6Bu3X76g@mail.gmail.com/
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 925a621..06cf053 100644 (file)
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -414,6 +414,8 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
        inode->i_mode = mode;
        inode->i_fop = fops ? fops : &tracefs_file_operations;
        inode->i_private = data;
+       inode->i_uid = d_inode(dentry->d_parent)->i_uid;
+       inode->i_gid = d_inode(dentry->d_parent)->i_gid;
        d_instantiate(dentry, inode);
        fsnotify_create(dentry->d_parent->d_inode, dentry);
        return end_creating(dentry);
@@ -436,6 +438,8 @@ static struct dentry *__create_dir(const char *name, struct dentry *parent,
        inode->i_mode = S_IFDIR | S_IRWXU | S_IRUSR| S_IRGRP | S_IXUSR | S_IXGRP;
        inode->i_op = ops;
        inode->i_fop = &simple_dir_operations;
+       inode->i_uid = d_inode(dentry->d_parent)->i_uid;
+       inode->i_gid = d_inode(dentry->d_parent)->i_gid;
 
        /* directory inodes start off with i_nlink == 2 (for "." entry) */
        inc_nlink(inode);