qemu: Add patch to fix incorrect permissions on samba >= 2.0.5

[nh2]

Motivation for this change

QEMU's builtin Samba config does not work for current Samba versions (including the one used in nixpkgs), see:

https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg07156.html

Discussion so far (note lists -> mail in the URL, the old mailing list URL doesn't seem to update any longer):

https://mail.gnu.org/archive/html/qemu-devel/2021-04/msg06741.html

Unfortunately nobody has replied to my patch yet.

I think it makes sense to have this in nixpkgs, because otherwise mounting QEMU-provided Samba shares for Windows VM guests does not work.

We've been using this patch successfully on our company infrastructure for the last 9 months.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

---

CC from #114064: @bb2020

CC from #94370: @andir

[bb2020]

My samba shared folder is working for Windows 7 guest. Is this a thing for newer Windows versions?

[SuperSandro2000]

Suggested change

	url = "https://github.com/nh2/qemu/commit/de30898a738bd073593d20930496ef63e54d62a3.patch";
	url = "https://github.com/qemu/qemu/commit/de30898a738bd073593d20930496ef63e54d62a3.patch";

makes it easier to track when it is merged.

[nh2]

My samba shared folder is working for Windows 7 guest. Is this a thing for newer Windows versions?

@bb2020 Are you using the -net user,smb=/path/to/folder QEMU option for your Samba share? That's what the patch fixes.

[alyssais]

@nh2 I notice the patch hasn't been discussed on the mailing list since April. Now would be a good time to resend it, because you might be able to make it into the soon-to-be-released 6.2.0, and because IME they're especially receptive to bug fixes during release candidate season.

[nh2]

Now would be a good time to resend it

I have sent another comment/request in there. Unfortunately https://mail.gnu.org/archive/html/qemu-devel/2021-04/msg06741.html doesn't seem to be anything close to realtime, so I cannot link it.

[alyssais]

Unfortunately https://mail.gnu.org/archive/html/qemu-devel/2021-04/msg06741.html doesn't seem to be anything close to realtime, so I cannot link it.

I find https://lore.kernel.org/qemu-devel/ to work much better in general -- maybe it's faster as well? Not sure.