linux-kernel - Re: [PATCH v1 2/9] fs/fuse: add FUSE_OWNER_UID_GID

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Date: Tue, 5 Mar 2024 15:38:43 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
Cc: mszeredi@...hat.com, brauner@...nel.org, stgraber@...raber.org, 
	linux-fsdevel@...r.kernel.org, Seth Forshee <sforshee@...nel.org>, 
	Amir Goldstein <amir73il@...il.com>, Bernd Schubert <bschubert@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/9] fs/fuse: add FUSE_OWNER_UID_GID_EXT extension

On Mon, 8 Jan 2024 at 13:10, Alexander Mikhalitsyn
<aleksandr.mikhalitsyn@...onical.com> wrote:
>
> To properly support vfs idmappings we need to provide
> a fuse daemon with the correct owner uid/gid for
> inode creation requests like mkdir, mknod, atomic_open,
> symlink.
>
> Right now, fuse daemons use req->in.h.uid/req->in.h.gid
> to set inode owner. These fields contain fsuid/fsgid of the
> syscall's caller. And that's perfectly fine, because inode
> owner have to be set to these values. But, for idmapped mounts
> it's not the case and caller fsuid/fsgid != inode owner, because
> idmapped mounts do nothing with the caller fsuid/fsgid, but
> affect inode owner uid/gid. It means that we can't apply vfsid
> mapping to caller fsuid/fsgid, but instead we have to introduce
> a new fields to store inode owner uid/gid which will be appropriately
> transformed.

Does fsuid/fsgid have any meaning to the server?

Shouldn't this just set in.h.uid/in.h.gid to the mapped ids?

Thanks,
Miklos