On Fri, Nov 12, 2021 at 5:14 PM Vladislav Yaroshchuk
> macOS provides networking API for VMs called 'vmnet.framework':
> We can provide its support as the new QEMU network backends which
> represent three different vmnet.framework interface usage modes:
> * `vmnet-shared`:
> allows the guest to communicate with other guests in shared mode and
> also with external network (Internet) via NAT. Has (macOS-provided)
> DHCP server; subnet mask and IP range can be configured;
> * `vmnet-host`:
> allows the guest to communicate with other guests in host mode.
> By default has enabled DHCP as `vmnet-shared`, but providing
> network unique id (uuid) can make `vmnet-host` interfaces isolated
> from each other and also disables DHCP.
> * `vmnet-bridged`:
> bridges the guest with a physical network interface.
> This backends cannot work on macOS Catalina 10.15 cause we use
> vmnet.framework API provided only with macOS 11 and newer. Seems
> that it is not a problem, because QEMU guarantees to work on two most
> recent versions of macOS which now are Big Sur (11) and Monterey (12).
> Also, we have one inconvenient restriction: vmnet.framework interfaces
> can create only privileged user:
> `$ sudo qemu-system-x86_64 -nic vmnet-shared`
> Attempt of `vmnet-*` netdev creation being unprivileged user fails with
> vmnet's 'general failure'.
> This happens because vmnet.framework requires `com.apple.vm.networking`
> entitlement which is: "restricted to developers of virtualization software.
> To request this entitlement, contact your Apple representative." as Apple
> documentation says:
Do you know how multipass work? Looks like it uses vmnet without privileges.
I've just checked this, and they still need root privileges. They have a
`multipassd` daemon which is launched as root by launchd by default.
bash-5.1$ ps axo ruser,ruid,comm | grep multipass
root 0 /Library/Application Support/com.canonical.multipass/bin/multipassd
root 0 /Library/Application Support/com.canonical.multipass/bin/hyperkit
That's the reason why it's required to 'enter a password' while multipass installation:
it creates launchd plist (kinda launch rule) and places it to /Library/LaunchDaemons/,
which can be done only with root privileges.
bash-5.1$ ll /Library/LaunchDaemons | grep multipass
-rw-r--r-- 1 root wheel 1.1K 15 Nov 12:47 com.canonical.multipassd.plist
And after this launchd launches this multipassd daemon as root every boot.
So an unprivileged user can launch a multipass VM instance, but actually the
`hyperkit` process which interacts with vmnet is gonna be launched by multipassd
running as root.
tl;dr sadly, we can't interact with vmnet.framework without having our binary correctly
signed and being an unprivileged user. Root privileges or special signature with
entitlement is required.
Thank you for your review, I will check it this week and reply as soon as possible.
> One more note: we still have quite useful but not supported
> 'vmnet.framework' features as creating port forwarding rules, IPv6
> NAT prefix specifying and so on.
> Nevertheless, new backends work fine and tested within `qemu-system-x86-64`
> on macOS Bir Sur 11.5.2 host with such nic models:
> * e1000-82545em
> * virtio-net-pci
> * vmxnet3
> The guests were:
> * macOS 10.15.7
> * Ubuntu Bionic (server cloudimg)
> This series partially reuses patches by Phillip Tennen:
> So I included his signed-off line into one of the commit messages and
> also here.
> v1 -> v2:
> Since v1 minor typos were fixed, patches rebased onto latest master,
> redundant changes removed (small commits squashed)
> v2 -> v3:
> - QAPI style fixes
> - Typos fixes in comments
> - `#include`'s updated to be in sync with recent master
> v3 -> v4:
> - Support vmnet interfaces isolation feature
> - Support vmnet-host network uuid setting feature
> - Refactored sources a bit
> v4 -> v5:
> - Missed 6.2 boat, now 7.0 candidate
> - Fix qapi netdev descriptions and styles
> (@subnetmask -> @subnet-mask)
> - Support vmnet-shared IPv6 prefix setting feature
> Signed-off-by: Phillip Tennen <email@example.com>
> Signed-off-by: Vladislav Yaroshchuk <firstname.lastname@example.org>
> Vladislav Yaroshchuk (6):
> net/vmnet: add vmnet dependency and customizable option
> net/vmnet: add vmnet backends to qapi/net
> net/vmnet: implement shared mode (vmnet-shared)
> net/vmnet: implement host mode (vmnet-host)
> net/vmnet: implement bridged mode (vmnet-bridged)
> net/vmnet: update qemu-options.hx
> meson.build | 4 +
> meson_options.txt | 2 +
> net/clients.h | 11 ++
> net/meson.build | 7 +
> net/net.c | 10 ++
> net/vmnet-bridged.m | 111 ++++++++++++
> net/vmnet-common.m | 325 ++++++++++++++++++++++++++++++++++
> net/vmnet-host.c | 111 ++++++++++++
> net/vmnet-shared.c | 92 ++++++++++
> net/vmnet_int.h | 48 +++++
> qapi/net.json | 127 ++++++++++++-
> qemu-options.hx | 25 +++
> scripts/meson-buildoptions.sh | 3 +
> 13 files changed, 874 insertions(+), 2 deletions(-)
> create mode 100644 net/vmnet-bridged.m
> create mode 100644 net/vmnet-common.m
> create mode 100644 net/vmnet-host.c
> create mode 100644 net/vmnet-shared.c
> create mode 100644 net/vmnet_int.h