linux-kernel - Re: [PATCH v2 01/10] vfs: move cap_convert_nscap() call into vfs

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Message-ID: <CAJfpegutxHPuEnUxapcwcwiEiND8Swdi7CSOMaU06qV9=uUdXA@mail.gmail.com>
Date:   Tue, 12 Jan 2021 11:04:46 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Miklos Szeredi <mszeredi@...hat.com>,
        linux-fsdevel@...r.kernel.org,
        overlayfs <linux-unionfs@...r.kernel.org>,
        LSM <linux-security-module@...r.kernel.org>,
        linux-kernel@...r.kernel.org, "Serge E. Hallyn" <serge@...lyn.com>
Subject: Re: [PATCH v2 01/10] vfs: move cap_convert_nscap() call into vfs_setxattr()

On Tue, Jan 12, 2021 at 10:43 AM Miklos Szeredi <miklos@...redi.hu> wrote:

> The following semantics would make a ton more sense, since getting a
> v2 would indicate that rootid is unknown:
>
> - if cap is v2 convert to v3 with zero rootid
> - after this, check if rootid needs to be translated, if not return v3
> - if yes, try to translate to current ns, if succeeds return translated v3
> - if not mappable, return v2
>
> Hmm?

Actually, it would make even more sense to simply skip unconvertible
caps and return -ENODATA.  In fact that's what I thought would happen
until I looked at the -EOPNOTSUPP fallback code in vfs_getxattr().

Serge, do you remember what was the reason for the unconverted fallback?

Thanks,
Miklos