| Message ID | 20241201-work-exportfs-v1-0-b850dda4502a@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | exportfs: add flag to allow marking export operations as only supporting file handles | expand |
On Sun, 2024-12-01 at 14:12 +0100, Christian Brauner wrote: > Hey, > > Some filesystems like kernfs and pidfs support file handles as a > convenience to enable the use of name_to_handle_at(2) and > open_by_handle_at(2) but don't want to and cannot be reliably exported. > Add a flag that allows them to mark their export operations accordingly > and make NFS check for its presence. > > @Amir, I'll reorder the patches such that this series comes prior to the > pidfs file handle series. Doing it that way will mean that there's never > a state where pidfs supports file handles while also being exportable. > It's probably not a big deal but it's definitely cleaner. It also means > the last patch in this series to mark pidfs as non-exportable can be > dropped. Instead pidfs export operations will be marked as > non-exportable in the patch that they are added in. > > Thanks! > Christian > > --- > Christian Brauner (4): > exportfs: add flag to indicate local file handles > kernfs: restrict to local file handles > ovl: restrict to exportable file handles > pidfs: restrict to local file handles > > fs/kernfs/mount.c | 1 + > fs/nfsd/export.c | 8 +++++++- > fs/overlayfs/util.c | 7 ++++++- > fs/pidfs.c | 1 + > include/linux/exportfs.h | 1 + > 5 files changed, 16 insertions(+), 2 deletions(-) > --- > base-commit: 74e20c5946ab3f8ad959ea34f63f21e157d3ebae > change-id: 20241201-work-exportfs-cd49bee773c5 > I've been following the pidfs filehandle discussion and this is exactly what I was thinking we needed: a way to explicitly label certain fstypes as unexportable via nfsd. Reviewed-by: Jeff Layton <jlayton@kernel.org>
On Sun, Dec 1, 2024 at 2:12 PM Christian Brauner <brauner@kernel.org> wrote: > > Hey, > > Some filesystems like kernfs and pidfs support file handles as a > convenience to enable the use of name_to_handle_at(2) and > open_by_handle_at(2) but don't want to and cannot be reliably exported. > Add a flag that allows them to mark their export operations accordingly > and make NFS check for its presence. > > @Amir, I'll reorder the patches such that this series comes prior to the > pidfs file handle series. Doing it that way will mean that there's never > a state where pidfs supports file handles while also being exportable. > It's probably not a big deal but it's definitely cleaner. It also means > the last patch in this series to mark pidfs as non-exportable can be > dropped. Instead pidfs export operations will be marked as > non-exportable in the patch that they are added in. Yeh, looks good! Apart from missing update to exporting.rst Reviewed-by: Amir Goldstein <amir73il@gmail.com> Thanks, Amir.
> On Dec 1, 2024, at 8:28 AM, Jeff Layton <jlayton@kernel.org> wrote: > > On Sun, 2024-12-01 at 14:12 +0100, Christian Brauner wrote: >> Hey, >> >> Some filesystems like kernfs and pidfs support file handles as a >> convenience to enable the use of name_to_handle_at(2) and >> open_by_handle_at(2) but don't want to and cannot be reliably exported. >> Add a flag that allows them to mark their export operations accordingly >> and make NFS check for its presence. >> >> @Amir, I'll reorder the patches such that this series comes prior to the >> pidfs file handle series. Doing it that way will mean that there's never >> a state where pidfs supports file handles while also being exportable. >> It's probably not a big deal but it's definitely cleaner. It also means >> the last patch in this series to mark pidfs as non-exportable can be >> dropped. Instead pidfs export operations will be marked as >> non-exportable in the patch that they are added in. >> >> Thanks! >> Christian >> >> --- >> Christian Brauner (4): >> exportfs: add flag to indicate local file handles >> kernfs: restrict to local file handles >> ovl: restrict to exportable file handles >> pidfs: restrict to local file handles >> >> fs/kernfs/mount.c | 1 + >> fs/nfsd/export.c | 8 +++++++- >> fs/overlayfs/util.c | 7 ++++++- >> fs/pidfs.c | 1 + >> include/linux/exportfs.h | 1 + >> 5 files changed, 16 insertions(+), 2 deletions(-) >> --- >> base-commit: 74e20c5946ab3f8ad959ea34f63f21e157d3ebae >> change-id: 20241201-work-exportfs-cd49bee773c5 >> > > I've been following the pidfs filehandle discussion and this is exactly > what I was thinking we needed: a way to explicitly label certain > fstypes as unexportable via nfsd. > > Reviewed-by: Jeff Layton <jlayton@kernel.org> > Acked-by: Chuck Lever <chuck.lever@oracle.com <mailto:chuck.lever@oracle.com>> Though, I wonder if a similar but separate prohibition mechanism might be necessary for other in-kernel network file system server implementations (eg, ksmbd). -- Chuck Lever
> Though, I wonder if a similar but separate prohibition > mechanism might be necessary for other in-kernel network > file system server implementations (eg, ksmbd). Oh hm, interesting question. I have no idea how ksmbd or 9p "exports" work. I really hope they don't allow exporting arbitrary pseudo-fses.
On Tue, 2024-12-03 at 10:08 +0100, Christian Brauner wrote: > > Though, I wonder if a similar but separate prohibition > > mechanism might be necessary for other in-kernel network > > file system server implementations (eg, ksmbd). > > Oh hm, interesting question. > I have no idea how ksmbd or 9p "exports" work. I really hope they don't > allow exporting arbitrary pseudo-fses. SMB is path-based so there's no worry about filehandles there. It looks like ksmbd keeps a set of ksmbd_share_config objects, that are configured by userland. If someone deliberately shares stuff under /proc, then I guess they get to keep all of the pieces. ;) 9P does use filehandles, but there is no in-kernel server, so far. Wedson had one in development at one point [1], but I haven't heard anything about it in a while. [1]: https://kangrejos.com/Async%20Rust%20and%209p%20server.pdf
On Sun, Dec 01, 2024 at 02:12:24PM +0100, Christian Brauner wrote: > Hey, > > Some filesystems like kernfs and pidfs support file handles as a > convenience to enable the use of name_to_handle_at(2) and > open_by_handle_at(2) but don't want to and cannot be reliably exported. > Add a flag that allows them to mark their export operations accordingly > and make NFS check for its presence. > > @Amir, I'll reorder the patches such that this series comes prior to the > pidfs file handle series. Doing it that way will mean that there's never > a state where pidfs supports file handles while also being exportable. > It's probably not a big deal but it's definitely cleaner. It also means > the last patch in this series to mark pidfs as non-exportable can be > dropped. Instead pidfs export operations will be marked as > non-exportable in the patch that they are added in. Can you please invert the polarity? Marking something as not supporting is always awkward. Clearly marking it as supporting something (and writing down in detail what is required for that) is much better, even it might cause a little more churn initially.
Hey, Some filesystems like kernfs and pidfs support file handles as a convenience to enable the use of name_to_handle_at(2) and open_by_handle_at(2) but don't want to and cannot be reliably exported. Add a flag that allows them to mark their export operations accordingly and make NFS check for its presence. @Amir, I'll reorder the patches such that this series comes prior to the pidfs file handle series. Doing it that way will mean that there's never a state where pidfs supports file handles while also being exportable. It's probably not a big deal but it's definitely cleaner. It also means the last patch in this series to mark pidfs as non-exportable can be dropped. Instead pidfs export operations will be marked as non-exportable in the patch that they are added in. Thanks! Christian --- Christian Brauner (4): exportfs: add flag to indicate local file handles kernfs: restrict to local file handles ovl: restrict to exportable file handles pidfs: restrict to local file handles fs/kernfs/mount.c | 1 + fs/nfsd/export.c | 8 +++++++- fs/overlayfs/util.c | 7 ++++++- fs/pidfs.c | 1 + include/linux/exportfs.h | 1 + 5 files changed, 16 insertions(+), 2 deletions(-) --- base-commit: 74e20c5946ab3f8ad959ea34f63f21e157d3ebae change-id: 20241201-work-exportfs-cd49bee773c5