The in-development Linux 7.3 kernel adds opt-in support in KSMBD, the in-kernel SMB3/CIFS server, for Apple Time Machine backups over SMB. This required reverse-engineering undocumented Apple 'AAPL' SMB2 extensions (Finder, stream, COPYCHUNK, sparse-file, CHANGE_NOTIFY, RPC compatibility), authored by Gael Blivet. Linux 7.3 KSMBD also gains SMB2 command sequence window support, SMB3 request replay support, per-share SMB3 encryption, and SMB Direct RDMA encryption. Separately, 33 SMB client fixes landed for 7.3, now maintained by Paulo Alcantara after Steve French's passing.
Questions this post answers
Does the Linux kernel's KSMBD SMB server support Apple Time Machine backups?
Yes, as of Linux 7.3, KSMBD gains opt-in support for Apple Time Machine backups over SMB via backupd. This works by implementing Apple's undocumented 'AAPL' SMB2 extensions, including Finder, stream, COPYCHUNK, sparse-file, CHANGE_NOTIFY, and RPC compatibility bits, which were reverse-engineered from client/server behavior and authored by Gael Blivet. The feature is opt-in for now since the extensions aren't officially documented. Teams standardizing Linux file servers for Mac backups can track kernel SMB updates like this on daily.dev.
What other SMB features are new in KSMBD for Linux 7.3?
Linux 7.3's KSMBD adds SMB2 command sequence window support, SMB3 request replay support, per-share SMB3 encryption support, and SMB Direct RDMA encryption support, alongside the new Apple Time Machine interoperability. These changes came through a kernel pull request covering multiple fixes and features for the in-kernel SMB3/CIFS server. Anyone tuning Linux SMB server security and performance can follow kernel-level changes like these on daily.dev.
Who maintains the Linux SMB client code after Steve French's passing?
Paulo Alcantara abruptly took over as SMB client maintainer following the unexpected passing of longtime maintainer Steve French. For Linux 7.3, thirty-three client fixes were merged under his maintainership, with no major new feature changes queued up in that update. Developers relying on Linux SMB/CIFS client stability can keep tabs on maintainer and fix changes via daily.dev.