tracefs: Have new files inherit the ownership of their parent

commit ee7f3666995d8537dec17b1d35425f28877671a9 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index efe078fe5d4a957f5eefbd4b8ed7b528d6794491..0db0e0138bf80b2e1a2b8b51a357c7ba526cbc54 100644 (file)
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -409,6 +409,8 @@ 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);
@@ -431,6 +433,8 @@ 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);