linux-kernel - Re: [PATCH] ext4: Don't reduce symlink i

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Date: Thu, 9 May 2024 10:27:58 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: Miklos Szeredi <miklos@...redi.hu>
Cc: David Howells <dhowells@...hat.com>,
        Max Kellermann <max.kellermann@...os.com>, Jan Kara <jack@...e.com>,
        Christian Brauner <brauner@...nel.org>, linux-ext4@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ext4: Don't reduce symlink i_mode by umask if no ACL
 support

On Thu, May 09, 2024 at 03:47:27PM +0200, Miklos Szeredi wrote:
> On Thu, 9 May 2024 at 15:41, David Howells <dhowells@...hat.com> wrote:
> 
> > diff --git a/fs/ext4/acl.h b/fs/ext4/acl.h
> > index ef4c19e5f570..566625286442 100644
> > --- a/fs/ext4/acl.h
> > +++ b/fs/ext4/acl.h
> > @@ -71,7 +71,8 @@ ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
> >         /* usually, the umask is applied by posix_acl_create(), but if
> >            ext4 ACL support is disabled at compile time, we need to do
> >            it here, because posix_acl_create() will never be called */
> > -       inode->i_mode &= ~current_umask();
> > +       if (!S_ISLNK(inode->i_mode))
> > +               inode->i_mode &= ~current_umask();
> 
> I think this should just be removed unconditionally, since the VFS now
> takes care of mode masking in vfs_prepare_mode().

The following is in the ext4 tree:

commit c77194965dd0dcc26f9c1671d2e74e4eb1248af5
Author: Max Kellermann <max.kellermann@...os.com>
Date:   Fri Mar 15 15:29:56 2024 +0100

    Revert "ext4: apply umask if ACL support is disabled"
    
    This reverts commit 484fd6c1de13b336806a967908a927cc0356e312.  The
    commit caused a regression because now the umask was applied to
    symlinks and the fix is unnecessary because the umask/O_TMPFILE bug
    has been fixed somewhere else already.
    
    Fixes: https://lore.kernel.org/lkml/28DSITL9912E1.2LSZUVTGTO52Q@mforney.org/
    Signed-off-by: Max Kellermann <max.kellermann@...os.com>
    Reviewed-by: Christian Brauner <brauner@...nel.org>
    Tested-by: Michael Forney <mforney@...rney.org>
    Link: https://lore.kernel.org/r/20240315142956.2420360-1-max.kellermann@ionos.com
    Signed-off-by: Theodore Ts'o <tytso@....edu>