March 2021 - Spectrum Development

[PATCH ucspi-vsock] vsockserver: consistently use {STDIN,STDOUT}_FILENO
by Alyssa Ross 18 Mar '21

18 Mar '21

--- vsockserver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/vsockserver.c b/vsockserver.c index 8f809ec..03d9838 100644 --- a/vsockserver.c +++ b/vsockserver.c @@ -110,7 +110,7 @@ int main(int argc, char *argv[]) diee(EX_OSERR, "dup2"); if (dup2(conn, STDOUT_FILENO) == -1) diee(EX_OSERR, "dup2"); - if (conn != 0 && conn != 1) + if (conn != STDIN_FILENO && conn != STDOUT_FILENO) close(conn); execvp(argv[optind], &argv[optind]); diee(EX_OSERR, "exec"); -- 2.30.0

2 2

[PATCH ucspi-vsock] vsockserver: consistently use diee instead of err
by Alyssa Ross 18 Mar '21

18 Mar '21

diee is our function that respects the verbosity setting. --- vsockserver.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/vsockserver.c b/vsockserver.c index 0317cd4..8f809ec 100644 --- a/vsockserver.c +++ b/vsockserver.c @@ -3,7 +3,6 @@ #define _GNU_SOURCE -#include <err.h> #include <errno.h> #include <inttypes.h> #include <stdbool.h> @@ -105,22 +104,22 @@ int main(int argc, char *argv[]) ilog("connection from %" PRIu32 " port %" PRIu32, rcid, rport); switch (child = fork()) { - case -1: err(EX_OSERR, "fork"); + case -1: diee(EX_OSERR, "fork"); case 0: if (dup2(conn, STDIN_FILENO) == -1) - err(EX_OSERR, "dup2"); + diee(EX_OSERR, "dup2"); if (dup2(conn, STDOUT_FILENO) == -1) - err(EX_OSERR, "dup2"); + diee(EX_OSERR, "dup2"); if (conn != 0 && conn != 1) close(conn); execvp(argv[optind], &argv[optind]); - err(EX_OSERR, "exec"); + diee(EX_OSERR, "exec"); } if (waitpid(child, NULL, 0) == -1) - err(EX_OSERR, "waitpid"); + diee(EX_OSERR, "waitpid"); close(conn); } - err(EX_OSERR, "accept"); + diee(EX_OSERR, "accept"); } -- 2.30.0

2 2

[PATCH ucspi-vsock] Use C11 noreturn instead of GNU attribute extension
by Alyssa Ross 18 Mar '21

18 Mar '21

--- log.h | 4 ++-- vsockclient.c | 8 ++++---- vsockserver.c | 6 +++--- 3 files changed, 9 insertions(+), 9 deletions(-) diff --git a/log.h b/log.h index a1b0c16..ea9e9cf 100644 --- a/log.h +++ b/log.h @@ -1,5 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-or-later -// SPDX-FileCopyrightText: 2020 Alyssa Ross <hi(a)alyssa.is> +// SPDX-FileCopyrightText: 2020-2021 Alyssa Ross <hi(a)alyssa.is> #include <stdarg.h> @@ -13,7 +13,7 @@ extern enum verbosity verbosity; // Log an error message, followed by strerrno(errno), then exit with // status eval. -void diee(int eval, const char *fmt, ...) __attribute__((noreturn)); +_Noreturn void diee(int eval, const char *fmt, ...); // Log an error message. void elog(const char *fmt, ...); diff --git a/vsockclient.c b/vsockclient.c index ff8b7dc..91e1320 100644 --- a/vsockclient.c +++ b/vsockclient.c @@ -1,5 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-or-later -// SPDX-FileCopyrightText: 2020 Alyssa Ross <hi(a)alyssa.is> +// SPDX-FileCopyrightText: 2020-2021 Alyssa Ross <hi(a)alyssa.is> #define _GNU_SOURCE @@ -7,9 +7,10 @@ #include <inttypes.h> #include <stdio.h> #include <stdlib.h> +#include <stdnoreturn.h> +#include <sys/socket.h> #include <sysexits.h> #include <unistd.h> -#include <sys/socket.h> #include <linux/vm_sockets.h> @@ -18,8 +19,7 @@ #include "util.h" #include "vsock.h" -static void ex_usage(void) __attribute__((noreturn)); -static void ex_usage(void) +noreturn static void ex_usage(void) { if (verbosity) fprintf(stderr, "Usage: %s [ -q | -Q | -v ] cid port prog...\n", diff --git a/vsockserver.c b/vsockserver.c index 2fb4f8e..0317cd4 100644 --- a/vsockserver.c +++ b/vsockserver.c @@ -1,5 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-or-later -// SPDX-FileCopyrightText: 2020 Alyssa Ross <hi(a)alyssa.is> +// SPDX-FileCopyrightText: 2020-2021 Alyssa Ross <hi(a)alyssa.is> #define _GNU_SOURCE @@ -9,6 +9,7 @@ #include <stdbool.h> #include <stdio.h> #include <stdlib.h> +#include <stdnoreturn.h> #include <string.h> #include <sys/socket.h> #include <sys/wait.h> @@ -22,8 +23,7 @@ #include "util.h" #include "vsock.h" -static void ex_usage(void) __attribute__((noreturn)); -static void ex_usage(void) +noreturn static void ex_usage(void) { if (verbosity) fprintf(stderr, "Usage: %s [ -1 ] [ -q | -Q | -v ] cid port prog...\n", -- 2.30.0

2 2

[PATCH ucspi-vsock] Makefile: remove vsock{server,client}.o in clean
by Alyssa Ross 18 Mar '21

18 Mar '21

--- Makefile | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 4f11b64..07ff09b 100644 --- a/Makefile +++ b/Makefile @@ -1,5 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-or-later -# SPDX-FileCopyrightText: 2020 Alyssa Ross <hi(a)alyssa.is> +# SPDX-FileCopyrightText: 2020-2021 Alyssa Ross <hi(a)alyssa.is> .POSIX: @@ -27,5 +27,6 @@ vsockclient.o: env.h log.h util.h vsock.h vsockserver.o: env.h log.h util.h vsock.h clean: - rm -f env.o log.o util.o vsock.o vsockclient vsockserver + rm -f env.o log.o util.o vsock.o \ + vsockclient.o vsockclient vsockserver.o vsockserver .PHONY: clean -- 2.30.0

2 2

[PATCH nixpkgs] spectrumPackages.spectrum-vm: fix without Wayland
by Alyssa Ross 16 Mar '21

16 Mar '21

This errored because of the undefined XDG_RUNTIME_DIR or WAYLAND_DISPLAY. I'd tried to prevent that by disabling -e around this part, but it turns out I should have disabled -u instead. --- pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in b/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in index 4fa0287a805..8d95c178689 100755 --- a/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in +++ b/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in @@ -55,7 +55,7 @@ do esac done -set +e +set +u if [ -n "$XDG_RUNTIME_DIR" ] then set -- -s "$XDG_RUNTIME_DIR" "$@" @@ -63,7 +63,7 @@ then then set -- --wayland-sock "$XDG_RUNTIME_DIR/$WAYLAND_DISPLAY" "$@" fi fi -set -e +set -u exec "$crosvm" run \ -p init=/sbin/init \ -- 2.27.0

2 4

[PATCH nixpkgs] spectrumPackages.rootfs: add /sys
by Alyssa Ross 16 Mar '21

16 Mar '21

Programs assume this and it's useful to have. --- pkgs/os-specific/linux/spectrum/rootfs/generic.nix | 2 +- pkgs/os-specific/linux/spectrum/rootfs/stage1.nix | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/pkgs/os-specific/linux/spectrum/rootfs/generic.nix b/pkgs/os-specific/linux/spectrum/rootfs/generic.nix index 778b18dafa0..0a99f99bd5b 100644 --- a/pkgs/os-specific/linux/spectrum/rootfs/generic.nix +++ b/pkgs/os-specific/linux/spectrum/rootfs/generic.nix @@ -31,7 +31,7 @@ let mkdir $out cd $out - mkdir bin sbin dev proc run tmp + mkdir bin sbin dev proc run sys tmp ln -s ${dash}/bin/dash bin/sh ln -s ${makeStage1 { inherit run; }} sbin/init cp -r ${./etc} etc diff --git a/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix b/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix index 75cfed56e7f..be7853316e9 100644 --- a/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix +++ b/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix @@ -27,6 +27,7 @@ writeScript "init-stage1" '' if { s6-mount -t devpts -o gid=4,mode=620 none /dev/pts } if { s6-mount -t tmpfs none /dev/shm } if { s6-mount -t proc none /proc } + if { s6-mount -t sysfs none /sys } if { s6-ln -s ${mesa.drivers} /run/opengl-driver } export HOME / -- 2.30.0

2 3

[PATCH nixpkgs] spectrumPackages.rootfs: fix custom path entries
by Alyssa Ross 16 Mar '21

16 Mar '21

Stage 1 was supposed to be able to take a list of PATH entries to prepend to the default PATH, but it didn't do anything with them. Now, it properly adds them to the PATH as early as possible during boot. This mechanism isn't currently used anywhere, but is very useful for debugging. --- pkgs/os-specific/linux/spectrum/rootfs/generic.nix | 3 ++- pkgs/os-specific/linux/spectrum/rootfs/stage1.nix | 7 +++++-- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/pkgs/os-specific/linux/spectrum/rootfs/generic.nix b/pkgs/os-specific/linux/spectrum/rootfs/generic.nix index 0a99f99bd5b..81fb80a614f 100644 --- a/pkgs/os-specific/linux/spectrum/rootfs/generic.nix +++ b/pkgs/os-specific/linux/spectrum/rootfs/generic.nix @@ -8,7 +8,8 @@ let makeStage1 = import ./stage1.nix { inherit writeScript lib - execline s6 s6-portable-utils s6-linux-utils s6-linux-init busybox mesa; + execline s6 s6-portable-utils s6-linux-utils s6-linux-init busybox mesa + path; }; makeServicesDir = import ./services.nix { diff --git a/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix b/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix index be7853316e9..6caf9ff93b8 100644 --- a/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix +++ b/pkgs/os-specific/linux/spectrum/rootfs/stage1.nix @@ -1,16 +1,19 @@ { writeScript, lib , execline, s6, s6-portable-utils, s6-linux-utils, s6-linux-init, busybox, mesa +, path ? [] }: { run ? "true" }: let - path = [ s6 s6-portable-utils s6-linux-utils s6-linux-init busybox execline ]; + path' = path ++ [ + s6 s6-portable-utils s6-linux-utils s6-linux-init busybox execline + ]; in writeScript "init-stage1" '' #! ${execline}/bin/execlineb -P - export PATH ${lib.makeBinPath path} + export PATH ${lib.makeBinPath path'} ${s6}/bin/s6-setsid -qb -- importas -i spectrumcmd spectrumcmd -- 2.30.0

2 2

[PATCH nixpkgs] spectrumPackages.spectrum-vm: fix without Wayland
by Alyssa Ross 15 Mar '21

15 Mar '21

This errored because of the undefined XDG_RUNTIME_DIR or WAYLAND_DISPLAY. I'd tried to prevent that by disabling -e around this part, but it turns out I should have disabled -u instead. --- pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in b/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in index 4fa0287a805..8d95c178689 100755 --- a/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in +++ b/pkgs/os-specific/linux/spectrum/spectrum-vm/spectrum-vm.in @@ -55,7 +55,7 @@ do esac done -set +e +set +u if [ -n "$XDG_RUNTIME_DIR" ] then set -- -s "$XDG_RUNTIME_DIR" "$@" @@ -63,7 +63,7 @@ then then set -- --wayland-sock "$XDG_RUNTIME_DIR/$WAYLAND_DISPLAY" "$@" fi fi -set -e +set -u exec "$crosvm" run \ -p init=/sbin/init \ -- 2.30.0

1 1

[PATCH linux] usbip: tools: usbipd: add s6 readiness notification
by Alyssa Ross 15 Mar '21

15 Mar '21

This implements the s6 readiness notification protocol[1]. When the daemon has started and is listening on its socket(s), it will emit a readiness notification on a user-specified file descriptor. systemd-based systems can also use the readiness notification, using the sdnotify-wrapper program[2]. [1]: https://skarnet.org/software/s6/s6-supervise.html [2]: https://skarnet.org/software/misc/sdnotify-wrapper.c Signed-off-by: Alyssa Ross <hi(a)alyssa.is> --- This is important for us in Spectrum to be able to run usbipd to export USB devices to other VMs. I plan to add this patch to linuxPackages.usbip in Spectrum nixpkgs. I might attempt to upstream it to Linux, but I'm not sure yet -- the s6 protocol is perfect for our needs but fairly obsure, so I'm not sure if they'd like it. tools/usb/usbip/src/usbipd.c | 70 ++++++++++++++++++++++++++++-------- 1 file changed, 55 insertions(+), 15 deletions(-) diff --git a/tools/usb/usbip/src/usbipd.c b/tools/usb/usbip/src/usbipd.c index 48398a78e88af..4ee41040735f4 100644 --- a/tools/usb/usbip/src/usbipd.c +++ b/tools/usb/usbip/src/usbipd.c @@ -22,6 +22,7 @@ #include <arpa/inet.h> #include <sys/socket.h> #include <netinet/in.h> +#include <fcntl.h> #ifdef HAVE_LIBWRAP #include <tcpd.h> @@ -65,6 +66,10 @@ static const char usbipd_help_string[] = " -D, --daemon\n" " Run as a daemon process.\n" "\n" + " -nFD, --notify-fd FD\n" + " Once ready to receive connections, write a line feed\n" + " character to FD, then close it.\n" + "\n" " -d, --debug\n" " Print debugging information.\n" "\n" @@ -88,6 +93,30 @@ static void usbipd_help(void) printf("%s\n", usbipd_help_string); } +static int parse_notify_fd(char *arg) +{ + dbg("parsing notify-fd arg '%s'", arg); + char *end; + unsigned long int notify_fd = strtoul(arg, &end, 10); + + if (end == arg) { + err("notify-fd: could not parse '%s' as decimal integer", arg); + return -1; + } + + if (*end != '\0') { + err("notify-fd: garbage at end of '%s'", arg); + return -1; + } + + if (fcntl(notify_fd, F_GETFD) == -1) { + err("notify-fd: %s", strerror(errno)); + return -1; + } + + return notify_fd; +} + static int recv_request_import(int sockfd) { struct op_import_request req; @@ -488,7 +517,7 @@ static void remove_pid_file(void) } } -static int do_standalone_mode(int daemonize, int ipv4, int ipv6) +static int do_standalone_mode(int daemonize, int notify_fd, int ipv4, int ipv6) { struct addrinfo *ai_head; int sockfdlist[MAXSOCKFD]; @@ -543,6 +572,13 @@ static int do_standalone_mode(int daemonize, int ipv4, int ipv6) dbg("listening on %d address%s", nsockfd, (nsockfd == 1) ? "" : "es"); + if (notify_fd != -1) { + const char lf[] = { '\n' }; + if (write(notify_fd, lf, sizeof lf) == -1) + err("failed to notify readiness"); + close(notify_fd); + } + fds = calloc(nsockfd, sizeof(struct pollfd)); for (i = 0; i < nsockfd; i++) { fds[i].fd = sockfdlist[i]; @@ -586,17 +622,18 @@ static int do_standalone_mode(int daemonize, int ipv4, int ipv6) int main(int argc, char *argv[]) { static const struct option longopts[] = { - { "ipv4", no_argument, NULL, '4' }, - { "ipv6", no_argument, NULL, '6' }, - { "daemon", no_argument, NULL, 'D' }, - { "daemon", no_argument, NULL, 'D' }, - { "debug", no_argument, NULL, 'd' }, - { "device", no_argument, NULL, 'e' }, - { "pid", optional_argument, NULL, 'P' }, - { "tcp-port", required_argument, NULL, 't' }, - { "help", no_argument, NULL, 'h' }, - { "version", no_argument, NULL, 'v' }, - { NULL, 0, NULL, 0 } + { "ipv4", no_argument, NULL, '4' }, + { "ipv6", no_argument, NULL, '6' }, + { "daemon", no_argument, NULL, 'D' }, + { "daemon", no_argument, NULL, 'D' }, + { "notify-fd", required_argument, NULL, 'n' }, + { "debug", no_argument, NULL, 'd' }, + { "device", no_argument, NULL, 'e' }, + { "pid", optional_argument, NULL, 'P' }, + { "tcp-port", required_argument, NULL, 't' }, + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, 'v' }, + { NULL, 0, NULL, 0 } }; enum { @@ -605,7 +642,7 @@ int main(int argc, char *argv[]) cmd_version } cmd; - int daemonize = 0; + int daemonize = 0, notify_fd = -1; int ipv4 = 0, ipv6 = 0; int opt, rc = -1; @@ -620,7 +657,7 @@ int main(int argc, char *argv[]) cmd = cmd_standalone_mode; driver = &host_driver; for (;;) { - opt = getopt_long(argc, argv, "46DdeP::t:hv", longopts, NULL); + opt = getopt_long(argc, argv, "46Dn:deP::t:hv", longopts, NULL); if (opt == -1) break; @@ -635,6 +672,9 @@ int main(int argc, char *argv[]) case 'D': daemonize = 1; break; + case 'n': + notify_fd = parse_notify_fd(optarg); + break; case 'd': usbip_use_debug = 1; break; @@ -665,7 +705,7 @@ int main(int argc, char *argv[]) switch (cmd) { case cmd_standalone_mode: - rc = do_standalone_mode(daemonize, ipv4, ipv6); + rc = do_standalone_mode(daemonize, notify_fd, ipv4, ipv6); remove_pid_file(); break; case cmd_version: -- 2.27.0

1 0

This Week in Spectrum, 2021-W10
by Alyssa Ross 14 Mar '21

14 Mar '21

Surprise! I sent the last This Week in Spectrum in August. Since then, it's been pretty quiet. What happened? Towards then end of last year, I was aggressively pushing to achieve a funding milestone, but was starting to struggle to keep myself going. After that last TWiS, I decided to stop posting them for a while to fully concentrate on the push. I continued like that for two more months, before getting to the point where I was so burned out I just couldn't keep going, with the milestone still not done, the work I had done so far on it unpublished (and not in a good state to be published), and time running out. Fortunately, I was able to talk to NLnet, and they agreed to extend my funding deadlines and renegotiate the milestones. With that sorted out, in late November I began a hiatus from Spectrum to allow myself to recover from the burnout. I'm very grateful to my GitHub Sponsors, thanks to whom I was able to take this time to recover. I tried to come back at the end of January, but after a single day of Spectrum work I was feeling much the same as I had been in November. This week, though, something changed! I've been working on Spectrum again for the last week, and I've been feeling great about it! Now, there were three months of work between the last TWiS in August, and the start of my hiatus. That's a lot of work I haven't written about. But I think the only way this is really going to work is if I leave that largely unwritten about for now, because TWiS tends to be thousands of words long even when it's covering a single week of work. So I'm just going to talk about what I've done in the last week, explaining context from previous work as necessary. With all that in mind, here we go! "Qubes-lite with KVM and Wayland"[1] ------------------------------------ First up is something somebody else did, which is always nice! Thomas has been doing his own great work replacing his Qubes system with a system built on NixOS, using KVM and Wayland. Thomas got in touch on the Spectrum discuss mailing list in January[2] asking some questions about how some things were implemented, and we went back and forth a bit then (although not as much as I'd have liked, due to my burnout :/). Since then, he's come up with some awesome stuff, like an OCaml implementation of a virtio-wayland proxy (equivalent to Sommelier in Chromium OS). In our further conversation prompted by Thomas's article, Thomas raised a further interesting idea[3] -- what if we had a Sommelier-like Wayland proxy, but that ran in the same security domain as the compositor. That way, we could filter to allow only the protocol extensions we want to. We could implement our own permissions when the compositor doesn't. This code would be responsible for securely handling Wayland messages from an untrusted guest, which would be beneficial because it would be a lot less code to audit, and because it could be written in a memory-safe language. This would avoid the need to write or find a secure Wayland compositor, and would in fact allow us to use virtually any compositor without having to worry nearly as much about its security credentials. I'm very excited by that idea, and I've been asking myself for the past few days why I didn't think of it before! I've thought several times "it's quite nice that Sommelier gives us a known subset of Wayland, but it's a shame we can't rely on it since it runs inside a application guest". But for some reason it just never occurred to me to follow that idea one step further, to "what if we had a similar program that run in the compositor's security domain". [1]: https://roscidus.com/blog/blog/2021/03/07/qubes-lite-with-kvm-and-wayland/ [2]: https://spectrum-os.org/lists/archives/spectrum-discuss/CAG4opy_hz_ESEpY0Tq… [3]: https://spectrum-os.org/lists/archives/spectrum-discuss/CAG4opy_JztAH3tD+ZU… uscpi-vsock ----------- ucspi-vsock[4] is a program I started writing in September. VSOCK[5] is a special Linux socket type that allows for communication between VMs, and I'm using it to allow services running in VMs (a USBIP daemon, for example), to notify the host (and by extension other VMs), when the service in the VM becomes ready to accept connections. USCPI[6] is a standard command interface for making it easy to do socket communication using standard IO primitives, without having to teach programs how to do socket connections for every kind of socket. There are several UCSPI implementations for common socket types like Internet and Unix domain sockets, but until now there was not one for VSOCK. So, for example, in a VM we can do: vsockclient 2 $port sh -c 'echo >&7' Which will connect to the host over VSOCK (in VSOCK the host is always address 2), write a newline, and close the connection. UCSPI lets us implement this with standard shell tools. There's an equivalent "vsockserver" program for the other end, that will run a command whenever a connection is received. Anyway, this week I went back to ucspi-vsock to fix some bugs[7][8][9][10]. As usual, (although I'm happy to realise this is still the case after all these months!) Cole was kind enough to review my patches. [4]: https://spectrum-os.org/git/ucspi-vsock/ [5]: https://man7.org/linux/man-pages/man7/vsock.7.html [6]: https://cr.yp.to/proto/ucspi.txt [7]: https://spectrum-os.org/lists/archives/spectrum-devel/20210309154048.14474-… [8]: https://spectrum-os.org/lists/archives/spectrum-devel/20210309171816.8589-1… [9]: https://spectrum-os.org/lists/archives/spectrum-devel/20210310204516.20041-… [10]: https://spectrum-os.org/lists/archives/spectrum-devel/20210310204555.20725-… Interguest networking --------------------- The bulk of my work this week has been in Spectrum's Nixpkgs, which is where (for now, at least) all the VM definitions and stuff live. Mostly, I've been trying to clean up months of frantic work into something I can actually publish as a series of patches, so it's out there instead of just on my computer! My focus at the moment is on doing this with the interguest networking implementation I wrote last year. The plan for this remains the same as last year: have a VM that manages all network hardware access and acts as a router for other VMs that need to talk to the outside world. Eventually, this will hopefully use virtio-vhost-user[11], which will allow us to avoid going through a networking stack on the host at all (or even having one), but until virtio-vhost-user is further along, we'll use bridge devices on the host to connect client VMs to the router. A very basic version of the latter is implemented and working for me locally -- I can run an application VM, and have it connect to another VM which runs the drivers for my ethernet port using VFIO (PCI passthrough). This code was a big ball of mud, and I'd also subtly broken it when I moved on from interguest networking last year to try to get a proof of concept going for another form of interguest communication. So I spent this week trying to page all the context I'd lost in the last few months back into my brain, making lots of partial git commits, writing commit messages, and fixing it up so that it works again. I think what I have is about ready to publish -- hopefully you'll see some patches next week. But what exists at the moment is still very limited -- the biggest limitation is that the router VM doesn't support hotplugging, so a VM that wants to connect to it actually has to be started first, before the router VM. Not good for something that should be run as a system service and likely started on boot! To overcome this limitation, I'll probably have to add support in crosvm for adding network devices at runtime using the control socket. I think this should be easy enough, and I haven't looked at what's happened in crosvm + rust-vmm since I've been away, so it's even possible somebody else will have done this already. [11]: https://wiki.qemu.org/Features/VirtioVhostUser So, the todo list for next week is getting the initial interguest networking PoC patchset posted. That'll come with a nice little demo other people will be able to try out if they want to. And then, I'll work on improving it further to the point where it's actually practical. I don't want to spend /too/ much time on this, since ultimately I do want to be using a virtio-vhost-user stack, which is quite different, but it's important to have an implementation of this so there's something to test further development (that doesn't care about the implementation details) against. My biggest worry at the moment is burning out again. Working in moderation isn't easy for me (I tend to get very sucked into things), but it's important for the project that I find a way to keep my work sustainable, so we don't lose time like this again. I'm still a little hesitant to say "this is it, I'm back for real". But the signs are looking good. Thank you for sticking with me through this.

1 0