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 0c123c5e70e08738f9dbe63859e289d8e9acc792..82e39fc8e86ea2cf4d45829cec182c127f3366cb 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);