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daemon: split owner daemon from root helper

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Move the supported systemd path to two services: an owner-user bangerd for
orchestration and a narrow root helper for bridge/tap, NAT/resolver, dm/loop,
and Firecracker ownership. This removes repeated sudo from daily vm and image
flows without leaving the general daemon running as root.

Add install metadata, system install/status/restart/uninstall commands, and a
system-owned runtime layout. Keep user SSH/config material in the owner home,
lock file_sync to the owner home, and move daemon known_hosts handling out of
the old root-owned control path.

Route privileged lifecycle steps through typed privilegedOps calls, harden the
two systemd units, and rewrite smoke plus docs around the supported service
model.

Verified with make build, make test, make lint, and make smoke on the
supported systemd host path.
This commit is contained in:
Thales Maciel 2026-04-26 12:43:17 -03:00
parent 3edd7c6de7
commit 59e48e830b
No known key found for this signature in database
GPG key ID: 33112E6833C34679
53 changed files with 3239 additions and 726 deletions
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34
internal/daemon/vm_disk.go
View file

@ -10,6 +10,7 @@ import (
"banger/internal/guestconfig"
"banger/internal/guestnet"
"banger/internal/model"
"banger/internal/roothelper"
"banger/internal/system"
)
@ -27,18 +28,19 @@ func (s *VMService) ensureSystemOverlay(ctx context.Context, vm *model.VMRecord)
// patchRootOverlay writes the per-VM config files (resolv.conf,
// hostname, hosts, sshd drop-in, network bootstrap, fstab) into the
// rootfs overlay. Reads the DM device path from the handle cache,
// which the start flow populates before calling this.
func (s *VMService) patchRootOverlay(ctx context.Context, vm model.VMRecord, image model.Image) error {
dmDev := s.vmHandles(vm.ID).DMDev
if dmDev == "" {
return fmt.Errorf("vm %q: DM device not in handle cache — start flow out of order?", vm.ID)
// rootfs overlay. The start flow passes the DM device path explicitly so the
// owner daemon can hand the privileged ext4 work to the root helper without
// rereading mutable process state.
func (s *VMService) patchRootOverlay(ctx context.Context, vm model.VMRecord, image model.Image, dmDev string) error {
if strings.TrimSpace(dmDev) == "" {
return fmt.Errorf("vm %q: DM device is required", vm.ID)
}
resolv := []byte(fmt.Sprintf("nameserver %s\n", s.config.DefaultDNS))
hostname := []byte(vm.Name + "\n")
hosts := []byte(fmt.Sprintf("127.0.0.1 localhost\n127.0.1.1 %s\n", vm.Name))
sshdConfig := []byte(sshdGuestConfig())
fstab, err := system.ReadDebugFSText(ctx, s.runner, dmDev, "/etc/fstab")
fstabBytes, err := s.privOps().ReadExt4File(ctx, dmDev, "/etc/fstab")
fstab := string(fstabBytes)
if err != nil {
fstab = ""
}
@ -70,19 +72,19 @@ func (s *VMService) patchRootOverlay(ctx context.Context, vm model.VMRecord, ima
s.capHooks.contributeGuest(builder, vm, image)
builder.WriteFile("/etc/fstab", []byte(builder.RenderFSTab(fstab)))
files := builder.Files()
writes := make([]roothelper.Ext4Write, 0, len(files))
for _, guestPath := range builder.FilePaths() {
data := files[guestPath]
mode := uint32(0o644)
if guestPath == guestnet.GuestScriptPath {
if err := system.WriteExt4FileMode(ctx, s.runner, dmDev, guestPath, 0o755, data); err != nil {
return err
}
continue
}
if err := system.WriteExt4File(ctx, s.runner, dmDev, guestPath, data); err != nil {
return err
mode = 0o755
}
writes = append(writes, roothelper.Ext4Write{
GuestPath: guestPath,
Data: files[guestPath],
Mode: mode,
})
}
return nil
return s.privOps().WriteExt4Files(ctx, dmDev, writes)
}
func (s *VMService) ensureWorkDisk(ctx context.Context, vm *model.VMRecord, image model.Image) (workDiskPreparation, error) {