examples/dummy.nix

@@ -13,8 +13,6 @@
 
   system.stateVersion = "25.11";
 
-  networking.hostName = "dummy";
-
   vmapps.enable = true;
   _module.args.inputs = import ../npins;
 

pkgs/ch-proxy/meson.build

@@ -1,9 +1,3 @@
 project('ch-proxy', 'c')
 
-pkg = import('pkgconfig')
-
-sendfd = library('sendfd', [ 'sendfd.c', 'sendfd.h' ], install: true)
-pkg.generate(sendfd)
-install_headers('sendfd.h')
-
-executable('ch-proxy', 'proxy.c', link_with: [sendfd], install: true)
+executable('ch-proxy', 'proxy.c', install: true)

pkgs/ch-proxy/package.nix

@@ -8,7 +8,6 @@
 stdenv.mkDerivation {
   pname = "ch-proxy";
   version = "0.0.0";
-  outputs = [ "out" "lib" ];
   nativeBuildInputs = [
     meson
     ninja
@@ -20,8 +19,6 @@ stdenv.mkDerivation {
     fs.toSource {
       fileset = fs.unions [
         ./proxy.c
-        ./sendfd.c
-        ./sendfd.h
         ./meson.build
       ];
       root = ./.;

pkgs/ch-proxy/proxy.c

@@ -9,9 +9,9 @@
 
 #include <linux/vm_sockets.h>
 
-#include "sendfd.h"
-
+struct msghdr mk_msghdr();
 int ch_connect(const char*, const char*);
+ssize_t send_fd(int, int);
 
 #define _WRITE_CONFIRM(fd, buf, buflen) {if (write((fd), (buf), (buflen)) != (buflen)) { perror("ch-proxy/write/partial write"); exit(EXIT_FAILURE); }}
 
@@ -168,13 +168,19 @@ int main(int argc, char** argv) {
         exit(EXIT_FAILURE);
     }
 
-    if (send_fd(1, s, NULL) == -1) {
+    if (send_fd(1, s) == -1) {
         perror("ssh-vsock-proxy/main/send_fd");
         return EXIT_FAILURE;
     }
     return 0;
 }
 
+struct msghdr mk_msghdr() {
+    struct msghdr msg;
+    memset(&msg, 0, sizeof(msg));
+
+    return msg;
+}
 
 int ch_connect(const char *path, const char *port) {
     int s = socket(AF_UNIX, SOCK_STREAM, 0);
@@ -206,3 +212,38 @@ int ch_connect(const char *path, const char *port) {
 
     return s;
 }
+
+ssize_t send_fd(int dst_fd, int fd) {
+    struct msghdr msg = mk_msghdr();
+
+    /* openssh expects to receive a dummy length=1 iovec? */
+    char ch;
+    struct iovec vec;
+    vec.iov_base = &ch;
+    vec.iov_len = 1;
+    msg.msg_iov = &vec;
+    msg.msg_iovlen = 1;
+
+    union {
+        struct cmsghdr align;
+        char buf[CMSG_SPACE(sizeof(int))];
+    } u;
+
+    msg.msg_control = u.buf;
+    msg.msg_controllen = sizeof(u.buf);
+
+    struct cmsghdr *cmptr;
+    cmptr = CMSG_FIRSTHDR(&msg);
+
+    if (cmptr == NULL) {
+        fprintf(stderr, "ch-proxy/send_fd/CMSG_FIRSTHDR: failed to initialize msg_control\n");
+        exit(EXIT_FAILURE);
+    }
+
+    cmptr->cmsg_len = CMSG_LEN(sizeof(int));
+    cmptr->cmsg_level = SOL_SOCKET;
+    cmptr->cmsg_type = SCM_RIGHTS;
+    *((int*) CMSG_DATA(cmptr)) = fd;
+
+    return (sendmsg(dst_fd, &msg, 0));
+}

pkgs/ch-proxy/sendfd.c

@@ -1,74 +0,0 @@
-#include "sendfd.h"
-#include "sys/socket.h" /* cmsghdr */
-#include "stdio.h" /* perror */
-
-
-ssize_t send_fd(int dst_fd, int fd, const struct iovec *iov) {
-    struct msghdr msg = { 0 };
-
-    /* openssh expects to receive a dummy length=1 iovec? */
-    char ch = 0;
-    struct iovec vecDefault = { 0 };
-    vecDefault.iov_base = &ch;
-    vecDefault.iov_len = 1;
-    msg.msg_iov = iov == NULL ? &vecDefault : iov;
-    msg.msg_iovlen = 1;
-
-    union {
-        struct cmsghdr align;
-        char buf[CMSG_SPACE(sizeof(int))];
-    } u;
-
-    msg.msg_control = u.buf;
-    msg.msg_controllen = sizeof(u.buf);
-
-    struct cmsghdr *cmptr;
-    cmptr = CMSG_FIRSTHDR(&msg);
-
-    if (cmptr == NULL) {
-        perror("ch-proxy/send_fd/CMSG_FIRSTHDR: failed to initialize msg_control\n");
-    }
-
-    cmptr->cmsg_len = CMSG_LEN(sizeof(int));
-    cmptr->cmsg_level = SOL_SOCKET;
-    cmptr->cmsg_type = SCM_RIGHTS;
-    *((int*) CMSG_DATA(cmptr)) = fd;
-
-    return (sendmsg(dst_fd, &msg, 0));
-}
-
-int recv_fd(int sock, int flags) {
-    int out = -1;
-
-    struct msghdr msg = { 0 };
-    struct cmsghdr *cmsg = NULL;
-    struct iovec iov = { 0 };
-    char dummy = 0;
-
-    msg.msg_iov = &iov;
-    msg.msg_iovlen = 1;
-
-    iov.iov_base = &dummy;
-    iov.iov_len = sizeof(dummy);
-
-    union {
-        struct cmsghdr align;
-        char buf[CMSG_SPACE(sizeof(int))];
-    } u;
-
-    msg.msg_control = u.buf;
-    msg.msg_controllen = sizeof(u.buf);
-
-    int bytes = 0;
-    if ((bytes = recvmsg(sock, &msg, flags)) < 0) {
-        perror("recv_fd: recvmsg");
-        return -1;
-    }
-    for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
-        if (cmsg->cmsg_level != SOL_SOCKET) { continue; }
-        if (cmsg->cmsg_type != SCM_RIGHTS) { continue; }
-        if (CMSG_LEN(cmsg) < sizeof(out)) { continue; }
-        out = *(int*)CMSG_DATA(cmsg);
-    }
-    return out;
-}

pkgs/ch-proxy/sendfd.h

@@ -1,27 +0,0 @@
-#ifndef _CH_PROXY_SENFD
-#define _CH_PROXY_SENFD
-
-#include <stddef.h> /* size_t */
-#include <sys/types.h> /* ssize_t */
-#include <sys/uio.h> /* iovec */
-
-
-/* send_fd(chanFd, fd, *iov)
- *
- * chanFd: fd to sendmsg over;
- * fd: fd to send;
- * iov: extra data to send or NULL;
- *
- * returns: result of sendmsg,
- * i.e. the number of bytes sent */
-ssize_t send_fd(int chanFd, int fd, const struct iovec *);
-
-/* recv_fd(chanFd, flags)
- *
- * chanFd: fd to recvmsg from;
- * flags: recvmsg flags e.g. 0, or MSG_CMSG_CLOEXEC?
- *
- * returns: the received fd or -1 */
-int recv_fd(int chanFd, int flags);
-
-#endif /* _CH_PROXY_SENFD */

pkgs/taps/.envrc

@@ -1 +0,0 @@
-use nix ../../ -A pkgs.taps

pkgs/taps/main.c

@@ -1,342 +0,0 @@
-#define _GNU_SOURCE
-
-#include <stdio.h>
-#include <stdlib.h> /* secure_getenv */
-#include <sys/socket.h>
-#include <unistd.h>
-#include <sys/un.h>
-#include <string.h>
-#include <stdbool.h>
-#include <ctype.h>
-#include <pwd.h>
-#include <fnmatch.h>
-#include <fcntl.h> /* open, O_NONBLOCK, &c */
-#include <err.h>
-#include <error.h>
-#include <errno.h>
-#include <sys/ioctl.h>
-#include <signal.h>
-#include <fcntl.h>
-
-#define __UAPI_DEF_IF_IFNAMSIZ 1
-#include <linux/if_tun.h>
-#include <linux/if.h>
-#include <linux/virtio_net.h>
-
-#include "sendfd.h"
-
-// From `man unix`
-#define SUN_PATH_SZ 108
-#define N_CONNS 16
-
-char *TEMP_PATHS[1024] = { 0 }; 
-int LAST_TEMP_PATH = -1;
-
-#define IFR_FLAGS_ALLOWED (IFF_NO_PI | IFF_TAP | IFF_TUN | IFF_VNET_HDR | IFF_MULTI_QUEUE | IFF_PERSIST)
-#define IFR_FLAGS_DEFAULT (IFF_NO_PI | IFF_TAP | IFF_VNET_HDR | IFF_PERSIST)
-
-#define PTR_OR_DIE(expr) TRUE_OR_DIE((expr) != NULL)
-#define DO_OR_DIE(expr) TRUE_OR_DIE((expr) != -1)
-#define TRUE_OR_DIE(expr, ...) TRUE_OR_(EXIT_FAILURE, expr, __VA_ARGS__)
-#define TRUE_OR_WARN(expr, ...) TRUE_OR_(0, expr, __VA_ARGS__)
-#define TRUE_OR_(status, expr, ...) \
-    do if (!(expr)) { \
-        error(status, errno, "Failed assertion: " #expr "." __VA_ARGS__); \
-    } while(false)
-
-struct allow_pattern {
-    // enum { USER = 1, GROUP = 2 } type;
-    // union { uid_t uid, gid_t gid } xid;
-    char *name;
-};
-struct allow_patterns {
-    size_t n;
-    struct allow_pattern *patterns;
-};
-
-/* Running on the same host, not caring for alignment */
-struct tap_request {
-    short ifrFlags; /* 0 to use defaults: IFF_TAP | IFF_NO_PI | IFF_VNET_HDR */
-    char name[IFNAMSIZ];
-};
-
-struct tap_reply {
-    enum { OK = 0, AUTH_ERROR = 1 } status;
-    char name[IFNAMSIZ];
-};
-
-int tuntap_alloc(char *dev, short openFlags, short ifrFlags, int *out_fd);
-
-bool match_mask(const char *test_addr, const char *expected_addr, const char *mask, int n) {
-    for (int octet = 0; octet < n; ++octet) {
-        if ((test_addr[octet] & mask[octet]) != expected_addr[octet]) {
-            return false;
-        }
-    }
-    return true;
-}
-
-/* 
- * Adapted from spectrum's `mktuntap.c` (2019 Alyssa Ross <hi@alyssa.is>
- * GPL-2.0-only), which in turn adapts `tun_alloc` from
- * `linux/Documentation/networking/tuntap.rst`.
- *
- * ifrFlags: IFF_TUN   - TUN device (no Ethernet headers)
- *           IFF_TAP   - TAP device
- *
- *           IFF_NO_PI - Do not provide packet information
- */
-int tuntap_alloc(char *dev, short openFlags, short ifrFlags, int *out_fd) {
-  struct ifreq ifr = { 0 };
-  int fd = -1, err = 0;
-
-  DO_OR_DIE(fd = open("/dev/net/tun", openFlags));
-
-  if (dev != NULL) {
-    int devLen = strlen(dev);
-    if (devLen >= IFNAMSIZ) {
-      /* If client requests a name, we do want the entire name to fit */
-      errno = EINVAL;
-      return EINVAL;
-    }
-    strncpy(ifr.ifr_name, dev, IFNAMSIZ - 1);
-  }
-  ifr.ifr_flags = ifrFlags;
-
-  TRUE_OR_WARN((err = ioctl(fd, TUNSETIFF, (void *)&ifr)) == 0);
-  if (err != 0) {
-    close(fd);
-    return err;
-  }
-
-  strncpy(dev, ifr.ifr_name, IFNAMSIZ);
-  *out_fd = fd;
-
-  {
-      int sz = sizeof(struct virtio_net_hdr_v1);
-      DO_OR_DIE(ioctl(fd, TUNSETVNETHDRSZ, &sz));
-  }
-  return 0;
-}
-
-int acceptRequests(const char *requestsPath, const struct allow_patterns *patterns) {
-    int listener;
-    struct sockaddr_un addr;
-    const int t = 1;
-
-    DO_OR_DIE(listener = socket(AF_UNIX, SOCK_SEQPACKET, 0));
-    DO_OR_DIE(setsockopt(listener, SOL_SOCKET, SO_PASSCRED, &t, sizeof(t)));
-
-    addr.sun_family = AF_UNIX;
-    strncpy(addr.sun_path, requestsPath, SUN_PATH_SZ - 1);
-    DO_OR_DIE (bind(listener, &addr, sizeof(addr)));
-    PTR_OR_DIE(TEMP_PATHS[++LAST_TEMP_PATH] = strdup(requestsPath));
-
-    DO_OR_DIE(listen(listener, N_CONNS));
-
-    for (;;) {
-        /* Already changed my mind about looking at ucred, but keeping the code around for now */
-        int sock = -1;
-        struct ucred cred = { 0 };
-        struct msghdr msg = { 0 };
-        struct cmsghdr *cmsg = NULL;
-        struct iovec iov = { 0 };
-        struct tap_request req = { 0 };
-
-        msg.msg_iov = &iov;
-        msg.msg_iovlen = 1;
-
-        iov.iov_base = &req;
-        iov.iov_len = sizeof(struct tap_request);
-
-        DO_OR_DIE((sock = accept(listener, NULL, NULL)));
-
-        TRUE_OR_DIE(recvmsg(sock, &msg, 0) > 0);
-        req.name[IFNAMSIZ] = 0;
-        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
-            if (cmsg->cmsg_level != SOL_SOCKET) { continue; }
-            if (cmsg->cmsg_type != SCM_CREDENTIALS) { continue; }
-            if (CMSG_LEN(cmsg) < sizeof(struct ucred)) { continue; }
-            memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
-            break;
-        }
-
-        if (req.ifrFlags == 0) {
-            req.ifrFlags = IFR_FLAGS_DEFAULT;
-        }
-
-        bool allowed = false;
-        for (int i = 0; !allowed && i < patterns->n; ++i) {
-            bool ifnameOk = fnmatch(patterns->patterns[i].name, req.name, 0) == 0;
-            bool flagsOk = (req.ifrFlags & IFR_FLAGS_ALLOWED) == req.ifrFlags;
-            allowed = ifnameOk && flagsOk;
-        }
-
-        struct tap_reply reply = { 0 };
-        if (!allowed) { reply.status = AUTH_ERROR; }
-        if (allowed) {
-            /* O_CLOEXEC? */
-            int fd = -1;
-            TRUE_OR_DIE(tuntap_alloc(req.name, O_RDWR | O_NONBLOCK, req.ifrFlags, &fd) == 0);
-            struct iovec iov = { 0 };
-            iov.iov_base = &reply;
-            iov.iov_len = sizeof(struct tap_reply);
-            TRUE_OR_DIE(send_fd(sock, fd, &iov) > 0);
-            close(fd); 
-        }
-        close(sock);
-    }
-    close(listener);
-}
-
-struct allow_patterns parsePatterns(const char *raw) {
-    const size_t rawLen = strlen(raw);
-
-    size_t nPatterns = 0;
-    for (int i = 0; i < rawLen; ++i) {
-        const int start = i;
-        if (isspace(raw[i])) { continue; }
-        for (; i < rawLen && !isspace(raw[i]); ++i) { }
-        if (start < i) { ++nPatterns; }
-    }
-
-    struct allow_pattern *patterns = NULL;
-    PTR_OR_DIE(patterns = calloc(nPatterns, sizeof(struct allow_pattern)));
-
-    int iPattern = 0;
-    for (int i = 0; i < rawLen; ++i) {
-        if (isspace(raw[i])) { continue; }
-        /* used to have per-group/per-user patterns, "u:$username:$pattern", &c - gone */
-        {
-            const int start = i;
-            for (; i < rawLen && !isspace(raw[i]); ++i) { }
-            if (start < i) {
-                PTR_OR_DIE(patterns[iPattern].name = strndup(&raw[start], i - start));
-                iPattern += 1;
-            }
-        }
-    }
-    struct allow_patterns out = {
-        .n = nPatterns,
-        .patterns = patterns
-    };
-    return out;
-}
-
-int get(const char *servePath, const char *ifname, short ifrFlags) {
-    /* TODO: sock: move out */
-    int sock;
-    struct sockaddr_un addr;
-
-    DO_OR_DIE(sock = socket(AF_UNIX, SOCK_SEQPACKET, 0));
-
-    addr.sun_family = AF_UNIX;
-    strncpy(addr.sun_path, servePath, SUN_PATH_SZ - 1);
-    DO_OR_DIE (connect(sock, &addr, sizeof(addr)));
-
-    struct msghdr msg = { 0 };
-    struct cmsghdr *cmsg = NULL;
-    struct iovec iov = { 0 };
-    struct tap_request req = { 0 };
-    strncpy(req.name, ifname, IFNAMSIZ - 1);
-    req.ifrFlags = ifrFlags;
-
-    msg.msg_iov = &iov;
-    msg.msg_iovlen = 1;
-
-    iov.iov_base = &req;
-    iov.iov_len = sizeof(struct tap_request);
-
-    TRUE_OR_DIE(sendmsg(sock, &msg, 0) > 0);
-
-    int tunFd = -1;
-    DO_OR_DIE(tunFd = recv_fd(sock, 0));
-    close(sock);
-    return tunFd;
-}
-
-void cleanup(int signo, siginfo_t *info, void *_context) {
-    for (int i = 0; i <= LAST_TEMP_PATH; ++i) {
-        TRUE_OR_DIE(unlink(TEMP_PATHS[i]) != -1 || errno == ENOENT);
-    }
-    if (signo == SIGINT) {
-        exit(EXIT_SUCCESS);
-    }
-    errx(EXIT_FAILURE, "Exiting with signal %d", signo);
-}
-
-/* skarlibs under ISC */
-int uncoe (int fd)
-{
-  int flags = fcntl(fd, F_GETFD, 0) ;
-  return flags < 0 ? flags : flags & FD_CLOEXEC ? fcntl(fd, F_SETFD, flags & ~FD_CLOEXEC) : 0 ;
-}
-
-int main(int argc, char **argv) {
-    struct sigaction act = { 0 };
-    act.sa_flags = SA_SIGINFO;
-    act.sa_sigaction = cleanup;
-    DO_OR_DIE(sigaction(SIGINT, &act, NULL));
-    DO_OR_DIE(sigaction(SIGSEGV, &act, NULL));
-
-    bool cmdServe = false;
-    bool cmdPass = false;
-    char *ifname = "vt-%d";
-
-    char **rest = argv + 1;
-    char **end = argv + argc;
-
-    TRUE_OR_DIE(argc > 1);
-    if (strcmp(rest[0], "serve") == 0) {
-        cmdServe = true;
-        ++rest;
-    } else if (strcmp(rest[0], "pass") == 0) {
-        cmdPass = true;
-        ++rest;
-        for (; rest != end && rest[0][0] == '-'; ++rest) {
-            if (strcmp(rest[0], "--")) { break; }
-            else if (strncmp(rest[0], "--ifname=", sizeof("--ifname="))) {
-                ifname = rest[0] + sizeof("--ifname=");
-            }
-        }
-    } else {
-        error(EINVAL, EINVAL, "no subcommand \"%s\"", rest[0]);
-    }
-
-    int nextArgc = argc - (rest - argv);
-    char * const* nextArgv = rest;
-
-    const char *patternsRaw = secure_getenv("TAPS_ALLOW");
-    if (patternsRaw == NULL) {
-        patternsRaw = "*";
-    }
-
-    struct allow_patterns patterns = { 0 };
-    if (cmdServe) {
-        PTR_OR_DIE((patterns = parsePatterns(patternsRaw)).patterns);
-    }
-
-    const char *servePath = secure_getenv("TAPS_SOCK");
-    if (servePath == NULL) {
-        servePath = "/run/taps/taps.sock";
-    }
-
-    if (cmdServe) {
-        acceptRequests(servePath, &patterns);
-    } else if (cmdPass) {
-        TRUE_OR_DIE(nextArgc > 0);
-        int fd = -1;
-        DO_OR_DIE(fd = get(servePath, ifname, 0));
-        if (fd != 3) {
-            DO_OR_DIE(dup2(fd, 3));
-            close(fd);
-            fd = 3;
-        }
-        uncoe(fd);
-        DO_OR_DIE(execvp(nextArgv[0], nextArgv));
-    } else {
-        error(EINVAL, EINVAL, "subcommand args");
-    }
-
-    return 0;
-}

pkgs/taps/meson.build

@@ -1,4 +0,0 @@
-project('taps', 'c')
-
-sendfd = dependency('sendfd')
-executable('taps', 'main.c', dependencies: [sendfd], install: true)

pkgs/taps/package.nix

@@ -1,44 +0,0 @@
-{
-  lib,
-  stdenv,
-  meson,
-  pkg-config,
-  rustc,
-  ninja,
-  ch-proxy,
-}:
-
-stdenv.mkDerivation {
-  pname = "taps";
-  version = "0.0.0";
-  src =
-    let
-      fs = lib.fileset;
-    in
-    fs.toSource {
-      root = ./.;
-      fileset = fs.unions [
-        ./meson.build
-        ./main.c
-      ];
-    };
-
-  nativeBuildInputs = [
-    ninja
-    meson
-    pkg-config
-    rustc
-  ];
-  buildInputs = [ ch-proxy ];
-}
-# { lib, rustPlatform }:
-#
-# rustPlatform.buildRustPackage {
-#     pname = "taps";
-#     version = "0.0.0";
-#     src = let fs = lib.filesystem; in fs.toSource {
-#         root = ./.;
-#         fileset = fs.unions [
-#         ];
-#     };
-# };

profiles/ch-runner.nix

@@ -10,112 +10,21 @@
 
 let
   cfg = config.uvms.cloud-hypervisor;
-
-  inherit (config.networking) hostName;
   inherit (config.debug.closure.erofs) layers;
-  inherit (lib)
-    mkOption
-    types
-    concatMapStringsSep
-    getExe
-    getExe'
-    getBin
-    ;
-
-  package = pkgs.cloud-hypervisor.overrideAttrs (oldAttrs: {
-    patches = oldAttrs.patches or [ ] ++ [
-      # ../patches/ch.patch
-    ];
-    buildType = "debug";
-    dontStrip = true;
-  });
-  uvmsPkgs = pkgs.callPackage ../pkgs { };
-
-  chSettingsFile = (pkgs.formats.json { }).generate "vm.json" cfg.settings;
-
-  uvmPrefix = "\${HOME}/uvms/${hostName}";
-  vmmSock = "${uvmPrefix}/vmm.sock";
-  elbPrefix = "${lib.getBin pkgs.execline}/bin";
-  s6Prefix = "${lib.getBin pkgs.s6}/bin";
-  writeElb = name: text: writeElb' name "-W" text;
-  writeElb' =
-    name: elArgs: text:
-    pkgs.writeTextFile {
-      inherit name;
-      destination = "/bin/${name}";
-      executable = true;
-      text = ''
-        #!${getExe' pkgs.execline "execlineb"}${lib.optionalString (elArgs != null) " "}${elArgs}
-        importas OLDPATH PATH
-        export PATH "${elbPrefix}:${s6Prefix}:''${OLDPATH}"
-        ${text}
-      '';
-    };
 in
 {
   options = {
     uvms.cloud-hypervisor.enable = lib.mkEnableOption "Configure guest (e.g. fileSystems)";
-    uvms.cloud-hypervisor.runner = mkOption {
-      type = types.package;
+    uvms.cloud-hypervisor.runner = lib.mkOption {
+      type = lib.types.package;
       description = "A naive script for running this system in cloud-hypervisor";
     };
-    uvms.cloud-hypervisor.debugger = mkOption {
-      type = types.lazyAttrsOf types.anything;
-      description = "Same but you can debug the kernel";
+    uvms.cloud-hypervisor.extraArgv = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
     };
-    uvms.cloud-hypervisor.settingsFile = mkOption {
-      type = types.package;
-      default = chSettingsFile;
-      defaultText = "...";
-      readOnly = true;
-    };
-    uvms.cloud-hypervisor.settings = mkOption {
-      default = { };
-      type = types.submodule {
-        freeformType = (pkgs.formats.json { }).type;
-        options = {
-          payload = {
-            cmdline = mkOption { type = types.str; };
-            kernel = mkOption { type = types.str; };
-            initramfs = mkOption {
-              type = types.str;
-              default = "${config.system.build.initialRamdisk}/${config.system.boot.loader.initrdFile}";
-            };
-          };
-          vsock = {
-            cid = mkOption {
-              type = types.int;
-              default = 4;
-            };
-            socket = mkOption {
-              type = types.str;
-              default = "vsock.sock";
-            };
-          };
-          "api-socket" = mkOption {
-            type = types.str;
-            default = "vmm.sock";
-          };
-          "serial".mode = mkOption {
-            type = types.str;
-            default = "File";
-          };
-          "serial".file = mkOption {
-            type = types.nullOr types.str;
-            default = "serial";
-          };
-          "console".mode = mkOption {
-            type = types.str;
-            default = "Pty";
-          };
-          "console".file = mkOption {
-            type = types.nullOr types.str;
-            default = null;
-          };
-          # "watchdog" = true;
-          # "seccomp" = true;
-        };
-      };
+    uvms.cloud-hypervisor.argv = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
     };
     uvms.cloud-hypervisor.extraCmdline = lib.mkOption {
       type = lib.types.listOf lib.types.str;
@@ -136,539 +45,34 @@ in
   };
   config = lib.mkMerge [
     {
-      uvms.cloud-hypervisor.settings = {
-        payload = {
-          cmdline = lib.concatStringsSep " " cfg.cmdline;
-          kernel = "${config.boot.kernelPackages.kernel}/${pkgs.stdenv.hostPlatform.linux-kernel.target}";
-        };
-        disks = map (img: {
-          path = img;
-          readonly = true;
-          id = toString img.label;
-        }) layers;
-        memory = {
-          size = 1536 * 1048576;
-          shared = true;
-          mergeable = true;
-          # hotplugged_size = 512 * 1048576;
-          # hotplugd_size = 1536 * 1048576;
-          # hotplug_method = "virtio-mem"
-        };
-        cpus = {
-          boot_vcpus = 4;
-          max_vcpus = 4;
-        };
-      };
-
-      uvms.cloud-hypervisor.debugger = pkgs.testers.runNixOSTest (
-        { config, ... }:
-        {
-          name = "test-run-${hostName}";
-          passthru = rec {
-            inherit (config.nodes.machine.system.build) gdbScript;
-            inherit (config.nodes.machine.boot.kernelPackages) kernel;
-            kernelSrc = pkgs.srcOnly kernel;
-          };
-          nodes.machine =
-            { config, ... }:
-            let
-              kernel = config.boot.kernelPackages.kernel;
-              kernelSrc = pkgs.srcOnly kernel;
-              gdbScript = writeElb "attach-gdb" ''
-                if { rm -rf /tmp/gdb }
-                if { mkdir -p /tmp/gdb/kos }
-                cd /tmp/gdb
-                if {
-                    elglob -0 files ${kernelSrc}/*
-                    forx -E f { $files }
-                    ln -s $f ./
-                }
-                if { mkdir -p build }
-                cd build
-                if {
-                    forx -E pattern { 
-                        ${kernel.modules}/lib/modules/*/kernel/drivers/net/tun*
-                        ${kernel.modules}/lib/modules/*/kernel/drivers/net/tap*
-                    }
-                    elglob -0 files $pattern
-                    forx -E f { $files }
-                    if { cp $f . }
-                    backtick -E COMPRESSED { basename $f }
-                    xz -d $COMPRESSED
-                }
-                elglob -0 GDB_SCRIPT_DIR ${lib.getDev kernel}/lib/modules/*/build/scripts/gdb
-                if {
-                    if { cp -r --no-preserve=all $GDB_SCRIPT_DIR gdb_scripts }
-                    mv gdb_scripts/linux/constants.py.in gdb_scripts/linux/constants.py
-                }
-                ${getExe pkgs.gdb}
-                -ex "python import sys; sys.path.insert(0, \"''${GDB_SCRIPT_DIR}\")"
-                -ex "target remote :1234"
-                -ex "source ''${GDB_SCRIPT_DIR}/vmlinux-gdb.py"
-                -ex "lx-symbols"
-                ${kernel.dev}/vmlinux
-              '';
-            in
-            {
-              boot.kernelPackages = pkgs.linuxPackagesFor (
-                (pkgs.linux.override (oldArgs: {
-                  # extraMakeFlags = oldArgs.extraMakeFlags or [ ] ++ [
-                  #   "scripts_gdb"
-                  # ];
-                  kernelPatches = oldArgs.kernelPatches or [ ] ++ [
-                    {
-                      name = "debug";
-                      patch = null;
-                      structuredExtraConfig = {
-                        GDB_SCRIPTS = lib.kernel.yes;
-                        DEBUG_INFO = lib.kernel.yes;
-                        DEBUG_INFO_REDUCED = lib.kernel.no;
-                        # FRAME_POINTER = lib.kernel.yes; # "unused option"???
-                        KALLSYMS = lib.kernel.yes;
-                        KGDB = lib.kernel.yes;
-                      };
-                    }
-                  ];
-                })).overrideAttrs
-                  (oldAttrs: {
-                    dontStrip = true;
-                    postInstall = oldAttrs.postInstall or "" + ''
-                      cp "$buildRoot/scripts/gdb/linux/constants.py" $dev/lib/modules/*/build/scripts/gdb/linux/ || echo "$buildRoot/scripts/gdb/linux/constants.py doesn't exist"
-                    '';
-                  })
-              );
-              boot.kernelParams = [ "nokaslr" ];
-              networking.useNetworkd = true;
-              virtualisation.qemu.options = [ "-s" ];
-              environment.systemPackages = [
-                pkgs.gdb
-                package # CH
-                cfg.runner
-                uvmsPkgs.taps
-              ];
-              system.build.gdbScript = gdbScript;
-              systemd.services.taps = {
-                wantedBy = [ "multi-user.target" ];
-                environment.TAPS_SOCK = "/run/taps/taps.sock";
-                serviceConfig = {
-                  UMask = "0007";
-                  ExecStart = "${getExe uvmsPkgs.taps} serve";
-                  RuntimeDirectory = "taps";
-                  DynamicUser = true;
-                  AmbientCapabilities = [
-                    "CAP_NET_BIND_SERVICE"
-                    "CAP_NET_ADMIN"
-                  ];
-                  NoNewPrivileges = true;
-                };
-              };
-            };
-          testScript = ''
-            machine.succeed("${getExe cfg.runner}")
-          '';
-        }
+      uvms.cloud-hypervisor.argv = lib.mkBefore (
+        [
+          (lib.getExe pkgs.cloud-hypervisor)
+          "--cmdline=${lib.concatStringsSep " " cfg.cmdline}"
+          "--kernel=${config.boot.kernelPackages.kernel}/${pkgs.stdenv.hostPlatform.linux-kernel.target}"
+          "--initramfs=${config.system.build.initialRamdisk}/${config.system.boot.loader.initrdFile}"
+          "--vsock=cid=4,socket=vsock.sock"
+          "--api-socket=vmm.sock"
+          "--serial=tty"
+          "--console=null"
+          "--watchdog"
+          "--seccomp=true"
+        ]
+        ++ cfg.extraArgv
       );
-
-      # NOTE: Used to be an even uglier bash script, but, for now, execline makes for easier comparisons against spectrum
-      uvms.cloud-hypervisor.runner =
-        let
-          toolsClosure = pkgs.writeClosure [
-            (lib.getBin pkgs.execline)
-            (lib.getBin pkgs.s6)
-            (lib.getBin package)
-            (lib.getBin pkgs.virtiofsd)
-            (lib.getBin pkgs.bubblewrap)
-            uvmsPkgs.taps
-          ];
-
-          superviseVm = getExe superviseVm';
-          superviseVm' = pkgs.writers.writePython3Bin "supervise-vm" { } ''
-            import os
-            import subprocess
-            import socket
-            from argparse import ArgumentParser
-            from contextlib import contextmanager, closing, ExitStack
-
-
-            parser = ArgumentParser("supervise-vm")
-            parser.add_argument("--vm")
-            parser.add_argument("--prefix", default="$HOME/uvms/$VM")
-            parser.add_argument("--sock", default="$PREFIX/supervisor.sock")
-            parser.add_argument("--vm-config")
-
-            MSG_SIZE = 16
-            ELB_DIR = "${lib.getBin pkgs.execline}/bin"  # noqa: E501
-            S6_DIR = "${lib.getBin pkgs.s6}/bin"  # noqa: E501
-            CH_DIR = "${lib.getBin package}/bin"  # noqa: E501
-            UTIL_LINUX_DIR = "${lib.getBin pkgs.util-linux}/bin"  # noqa: E501
-            SOCKETBINDER_PATH = S6_DIR + "/s6-ipcserver-socketbinder"  # noqa: E501
-            CH_PATH = CH_DIR + "/cloud-hypervisor"
-            CHR_PATH = CH_DIR + "/ch-remote"
-            TAPS_PATH = "${lib.getExe uvmsPkgs.taps}"  # noqa: E501
-            VIRTIOFSD_PATH = "${lib.getExe pkgs.virtiofsd}"  # noqa: E501
-            BWRAP_PATH = "${lib.getExe pkgs.bubblewrap}"  # noqa: E501
-
-            with open("${toolsClosure}", mode="r") as f:  # noqa: E501
-                CLOSURE = [
-                    *(ln.rstrip() for ln in f.readlines()),
-                    "${placeholder "out"}",  # noqa: E501
-                ]
-
-            PASSTHRU_PATH = ":".join([ELB_DIR, S6_DIR, CH_DIR, UTIL_LINUX_DIR])
-            PASSTHRU_ENV = {
-                **{
-                    k: v
-                    for k, v in os.environ.items()
-                    if k.startswith("RUST")
-                    or k.startswith("WAYLAND")
-                    or k in [
-                        "TAPS_SOCK",
-                    ]
-                },
-                "HOME": os.environ.get("HOME", os.getcwd()),
-                "PATH": PASSTHRU_PATH,
-            }
-
-
-            def preprocess_args(args_mut):
-                keys = [
-                    k
-                    for k, v
-                    in args_mut._get_kwargs()
-                    if isinstance(v, str)]
-                for k in keys:
-                    v = getattr(args_mut, k)
-                    if "$HOME" in v:
-                        setattr(
-                            args_mut,
-                            k,
-                            v.replace("$HOME", PASSTHRU_ENV["HOME"]))
-                for k in keys:
-                    v = getattr(args_mut, k)
-                    if "$VM" in v:
-                        setattr(args_mut, k, v.replace("$VM", args.vm))
-                for k in keys:
-                    v = getattr(args_mut, k)
-                    if "$PREFIX" in v:
-                        setattr(args_mut, k, v.replace("$PREFIX", args.prefix))
-                return args_mut
-
-
-            class Processes:
-                def __init__(self, prefix, vm, check=True, **defaults):
-                    self.prefix = prefix
-                    self.vm = vm
-                    self.check = check
-                    self.defaults = defaults
-
-                def make_env(self):
-                    return {
-                        **PASSTHRU_ENV,
-                        "PATH": PASSTHRU_PATH,
-                        "PREFIX": self.prefix,
-                        "VM": self.vm,
-                    }
-
-                def exec(self, *args, **kwargs):
-                    kwargs["cwd"] = kwargs.get("cwd", self.prefix)
-                    kwargs["check"] = kwargs.get("check", self.check)
-                    kwargs["env"] = kwargs.get("env", self.make_env())
-                    return subprocess.run(
-                        [*args],
-                        **self.defaults,
-                        **kwargs)
-
-                def execline(self, *args, **kwargs):
-                    return exec(
-                        "execlineb", "-c", "\n".join(args),
-                        **self.defaults,
-                        executable=ELB_DIR + "/execlineb",
-                        **{
-                            "env": self.make_env(),
-                            "check": self.check,
-                            "cwd": self.prefix,
-                            **kwargs,
-                        },
-                        )
-
-                def popen(self, *args, **kwargs):
-                    kwargs["pass_fds"] = kwargs.get("pass_fds", ())
-                    kwargs["env"] = kwargs.get("env", self.make_env())
-                    kwargs["cwd"] = kwargs.get("cwd", self.prefix)
-                    return subprocess.Popen(
-                        args,
-                        **kwargs,
-                    )
-
-                @contextmanager
-                def bwrap(
-                        self,
-                        *bwrap_args,
-
-                        die_with_parent=True,
-
-                        # Based on the args from
-                        # `host/rootfs/image/usr/bin/run-vmm`
-                        unshare_all=True,
-                        unshare_user=True,
-                        unshare_ipc=None,
-                        unshare_pid=None,
-                        unshare_net=None,
-                        unshare_uts=None,
-                        unshare_cgroup_try=True,
-                        bind=(),
-                        dev_bind=("/dev/kvm", "/dev/vfio"),
-                        dev="/dev",
-                        proc="/proc",
-                        ro_bind=(
-                            "/etc",
-                            "/sys",
-                            "/proc/sys",
-                            "/dev/null",
-                            "/proc/kallsyms",
-                            *CLOSURE),
-                        ro_bind_extra=(),
-                        remount_ro=("/proc/fs", "/proc/irq"),
-                        tmpfs=("/dev/shm", "/tmp", "/var/tmp", "/proc/fs", "/proc/irq"),
-                        tmpfs_extra=(),
-
-                        pass_fds=(2,),
-                        **popen_kwargs):
-
-                    bwrap_args_sock, remote = socket.socketpair()
-                    remote.set_inheritable(True)
-                    bwrap_args_f = bwrap_args_sock.makefile("w")
-                    with closing(bwrap_args_sock), closing(bwrap_args_f):
-                        def print_arg(*args):
-                            print(*args, file=bwrap_args_f, sep="\0", end="\0")
-
-                        if unshare_all:
-                            print_arg("--unshare-all")
-                        if unshare_user:
-                            print_arg("--unshare-user")
-                        if unshare_ipc:
-                            print_arg("--unshare-ipc")
-                        if unshare_pid:
-                            print_arg("--unshare-pid")
-                        if unshare_net:
-                            print_arg("--unshare-net")
-                        if unshare_uts:
-                            print_arg("--unshare-uts")
-                        if unshare_cgroup_try:
-                            print_arg("--unshare-cgroup-try")
-                        if die_with_parent:
-                            print_arg("--die-with-parent")
-
-                        for p in bind:
-                            p1, p2 = (p, p) if isinstance(p, str) else p
-                            print_arg("--bind", p1, p2)
-                        for p in (*ro_bind, *ro_bind_extra):
-                            p1, p2 = (p, p) if isinstance(p, str) else p
-                            print_arg("--ro-bind", p1, p2)
-                        for p in dev_bind:
-                            p1, p2 = (p, p) if isinstance(p, str) else p
-                            print_arg("--dev-bind", p1, p2)
-                        for p in (*tmpfs, *tmpfs_extra):
-                            print_arg("--tmpfs", p)
-                        # Hunch: order might matter...
-                        for p in remount_ro:
-                            print_arg("--remount-ro", p)
-
-                        bwrap_args_f.flush()
-
-                        with closing(remote):
-                            proc = self.popen(
-                                "bwrap", "--args", str(remote.fileno()), *bwrap_args,
-                                **popen_kwargs,
-                                executable=BWRAP_PATH,
-                                pass_fds=(*pass_fds, remote.fileno()),
-                            )
-
-                    with proc as p:
-                        try:
-                            yield p
-                        finally:
-                            try:
-                                p.poll()
-                            except:  # noqa: E722
-                                pass
-                            if p.returncode is None:
-                                p.terminate()
-                                p.wait()
-
-                @contextmanager
-                def run_ch(self):
-                    args = [
-                        SOCKETBINDER_PATH,
-                        "-B",
-                        self.prefix + "/vmm.sock",
-                        CH_PATH,
-                        "--api-socket",
-                        "fd=0",
-                    ]
-                    p = self.popen(
-                        *args,
-                        shell=False,
-                        stdin=subprocess.DEVNULL,
-                        stdout=subprocess.DEVNULL,
-                        pass_fds=(2,))
-                    try:
-                        p.wait(0.125)
-                        needs_cleanup = False
-                    except subprocess.TimeoutExpired:
-                        needs_cleanup = True
-                    if not os.path.exists(self.prefix + "/vmm.sock"):
-                        raise RuntimeError(f"{self.prefix}/vmm.sock should exist by now")
-                    if p.returncode is not None:
-                        raise RuntimeError("CH exited early")
-                    try:
-                        yield p
-                    finally:
-                        try:
-                            p.poll()
-                        except:  # noqa: E722
-                            pass
-                        if p.returncode is None:
-                            p.terminate()  # CH handles SIG{INT,TERM}?
-                            p.wait()
-                        unlink_paths = [
-                            self.prefix + "/vmm.sock",
-                            self.prefix + "/vmm.sock.lock",
-                            self.prefix + "/vsock.sock",
-                        ] if needs_cleanup else []
-                        for p in unlink_paths:
-                            if os.path.exists(p):
-                                os.remove(p)
-
-                @contextmanager
-                def add_virtiofsd(
-                        self,
-                        root_dir,
-                        tag,
-                        ro=False,
-                        subdirs=None,
-                        extra_flags=("--posix-acl",)):
-
-                    assert os.path.exists(root_dir)
-
-                    sock_path = self.prefix + f"/virtiofsd-{tag}.sock"
-                    # s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-                    # NOTE: Nope. Virtiofsd actually expects a blocking socket
-                    # s.setblocking(True)
-
-                    def rm_sock():
-                        if os.path.exists(sock_path):
-                            os.remove(sock_path)
-
-                    with ExitStack() as cleanup:  # noqa: F841
-                        # s.bind(sock_path.encode("utf8"))
-                        # cleanup.enter_context(closing(s))
-                        cleanup.enter_context(defer(rm_sock))
-
-                        args = [
-                            # If using bwrap():
-                            # "--argv0", "virtiofsd",
-                            # "--uid", "1000",
-                            # "--gid", "1000",
-                            # "--",
-                            "unshare", "-rUm",
-                            "unshare", "--map-user", "1000", "--map-group", "1000",
-                            VIRTIOFSD_PATH,
-                            "--shared-dir",
-                            root_dir,
-                            "--tag",
-                            tag,
-
-                            # "--fd",
-                            # str(s.fileno()),
-                            "--socket-path",
-                            sock_path,
-
-                            # If relying on bwrap():
-                            # "--sandbox",
-                            # "none",
-                        ]
-                        if ro:
-                            args.append("--readonly")
-                        kwargs = {
-                            # If bwrap():
-                            # "bind": [],
-                            # ("ro_bind_extra" if ro else "bind"):
-                            #     [*subdirs]
-                            #     if subdirs is not None
-                            #     else [root_dir],
-
-                            # "pass_fds": (2, s.fileno()),
-                        }
-                        proc_ctx = self.popen(*args, **kwargs)
-                        with proc_ctx as p:
-                            try:
-                                try:
-                                    p.wait(0.125)
-                                except subprocess.TimeoutExpired:
-                                    pass
-                                if p.returncode is not None:
-                                    raise RuntimeError("virtiofsd exited too early")
-                                yield p, sock_path
-                            finally:
-                                if p.returncode is None:
-                                    p.kill()
-                                    p.wait()
-                                if os.path.exists(sock_path):
-                                    os.remove(sock_path)
-
-
-            @contextmanager
-            def defer(f):
-                try:
-                    yield
-                finally:
-                    f()
-
-
-            if __name__ == "__main__":
-                args, args_next = parser.parse_known_args()
-                preprocess_args(args)
-
-                os.makedirs(args.prefix, exist_ok=True)
-                ps = Processes(
-                    prefix=args.prefix,
-                    vm=args.vm,
-                )
-
-                ch_remote = [
-                    "ch-remote",
-                    "--api-socket",
-                    args.prefix + "/vmm.sock",
-                ]
-
-                with ExitStack() as cleanup:
-                    ch = cleanup.enter_context(ps.run_ch())
-                    ps.exec(*ch_remote, "create", args.vm_config)
-                    ps.exec(
-                        TAPS_PATH, "pass",
-                        *ch_remote, "add-net",
-                        "id=wan,fd=3,mac=00:00:00:00:00:01")
-
-                    send_dir = PASSTHRU_ENV["HOME"] + f"/send/{args.vm}"
-                    os.makedirs(send_dir, exist_ok=True)
-                    vfsd, vfsd_path = cleanup.enter_context(
-                        ps.add_virtiofsd(
-                            send_dir,
-                            tag="send",
-                        ))
-                    ps.exec(*ch_remote, "add-fs", f"tag=send,socket={vfsd_path},id=send")
-                    ps.exec(*ch_remote, "boot")
-                    ps.exec(*ch_remote, "info")
-                    try:
-                        ch.wait()
-                    except KeyboardInterrupt:
-                        pass
-          '';
-        in
-        writeElb "run-${hostName}" ''
-          ${superviseVm} --vm-config=${chSettingsFile} --vm=${hostName}
-        '';
+      uvms.cloud-hypervisor.runner = pkgs.writeShellScriptBin "run-${config.networking.hostName}" ''
+        set -euo pipefail
+        GUESTNAME=${config.networking.hostName}
+        args=(
+        ${lib.concatMapStringsSep "\n" lib.escapeShellArg cfg.argv}
+        )
+        mkdir -p "$HOME/uvms/$GUESTNAME"
+        cd "$HOME/uvms/$GUESTNAME"
+        cleanup() {
+            rm "$HOME/uvms/$GUESTNAME"/{vmm,vsock}.sock
+        }
+        exec -a "uuvm/$GUESTNAME" "''${args[@]}"
+      '';
     }
     (lib.mkIf cfg.enable {
       boot.initrd.availableKernelModules = [
@@ -699,6 +103,12 @@ in
           }
         ) layers
       );
+      uvms.cloud-hypervisor.argv = [
+        "--memory=size=1536M,hotplug_size=1536M,hotplugged_size=512M,hotplug_method=virtio-mem,mergeable=on,shared=on"
+        "--cpus=boot=4"
+        "--disk"
+      ]
+      ++ map (img: "path=${img},readonly=true,id=${toString img.label}") layers;
     })
   ];
 }

profiles/uvms-guest.nix

@@ -41,7 +41,6 @@ in
         volumes = [
           {
             image = "swapfile.img";
-            serial = "swapfiles";
             mountPoint = "/var/swapfiles";
             size = 1024;
           }

profiles/uvms-users.nix

@@ -29,6 +29,7 @@ in
   };
   config = mergeIf cfg.enable [
     {
+      services.getty.autologinUser = "user";
       security.sudo.wheelNeedsPassword = false;
       users.mutableUsers = false;
       users.users.user = {

shell.nix

@@ -1,13 +0,0 @@
-with import <nixpkgs> { };
-
-mkShell.override { stdenv = stdenvNoCC; } {
-  packages = map lib.getBin [
-    cloud-hypervisor
-    virtiofsd
-    crosvm # virtio-gpu
-    npins
-  ] ++ [
-    man-pages
-    linux-manual
-  ];
-}