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Re: [PATCH] xfs: fix sgid inheritance for subdirectories inheriting defa

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH] xfs: fix sgid inheritance for subdirectories inheriting default acls [V2]
From: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Date: Wed, 19 Jun 2013 10:29:22 -0300
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20130618224351.GB29338@dastard>
References: <1371569536-5779-1-git-send-email-cmaiolino@xxxxxxxxxx> <20130618224351.GB29338@dastard>
User-agent: Mutt/1.5.21 (2010-09-15)
Hi Dave,

> > @@ -594,9 +594,10 @@ xfs_setattr_nonsize(
> >              * The set-user-ID and set-group-ID bits of a file will be
> >              * cleared upon successful return from chown()
> >              */
> > -           if ((ip->i_d.di_mode & (S_ISUID|S_ISGID)) &&
> > -               !capable(CAP_FSETID))
> > -                   ip->i_d.di_mode &= ~(S_ISUID|S_ISGID);
> > +           if (!S_ISDIR(inode->i_mode))
> > +                   if ((ip->i_d.di_mode & (S_ISUID|S_ISGID)) &&
> > +                       !capable(CAP_FSETID))
> > +                           ip->i_d.di_mode &= ~(S_ISUID|S_ISGID);
> 
> I'm not sure I understand why this is part of this patch - the ACL
> path does not enter this code branch (ATTR_UID/GID) so it doesn't
> affect ACL inheritence. So this is some other behavioural change?
> 
My apologies to have not commented it.

During my code surfing to understand the problem, and what places we revoked
sgid, I found this one, and, based on chmod specifications, we should keep sgid
on the directory while chmoding it, unless the user explicitly ask for sgid
removal, otherwise, if chmoding a file, we remove sgid if this isn't specified
in the new mode. So, I've added a check here to ensure the inode isn't a dir
before remove the sgid bit.

Should I remove it from the patch?
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@xxxxxxxxxxxxx

-- 
Carlos

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