diff options
Diffstat (limited to 'system/dbus/proc.go')
| -rw-r--r-- | system/dbus/proc.go | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/system/dbus/proc.go b/system/dbus/proc.go new file mode 100644 index 00000000..e8cccd5f --- /dev/null +++ b/system/dbus/proc.go @@ -0,0 +1,189 @@ +package dbus + +import ( + "context" + "errors" + "os" + "os/exec" + "path" + "path/filepath" + "slices" + "strconv" + "syscall" + + "git.gensokyo.uk/security/hakurei" + "git.gensokyo.uk/security/hakurei/helper" + "git.gensokyo.uk/security/hakurei/ldd" + "git.gensokyo.uk/security/hakurei/seccomp" +) + +// Start starts and configures a D-Bus proxy process. +func (p *Proxy) Start() error { + if p.final == nil || p.final.WriterTo == nil { + return syscall.ENOTRECOVERABLE + } + + p.mu.Lock() + defer p.mu.Unlock() + p.pmu.Lock() + defer p.pmu.Unlock() + + if p.cancel != nil || p.cause != nil { + return errors.New("dbus: already started") + } + + ctx, cancel := context.WithCancelCause(p.ctx) + + if !p.useSandbox { + p.helper = helper.NewDirect(ctx, p.name, p.final, true, argF, func(cmd *exec.Cmd) { + if p.CmdF != nil { + p.CmdF(cmd) + } + if p.output != nil { + cmd.Stdout, cmd.Stderr = p.output, p.output + } + cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true} + cmd.Env = make([]string, 0) + }, nil) + } else { + toolPath := p.name + if filepath.Base(p.name) == p.name { + if s, err := exec.LookPath(p.name); err != nil { + return err + } else { + toolPath = s + } + } + + var libPaths []string + if entries, err := ldd.ExecFilter(ctx, p.CommandContext, p.FilterF, toolPath); err != nil { + return err + } else { + libPaths = ldd.Path(entries) + } + + p.helper = helper.New( + ctx, toolPath, + p.final, true, + argF, func(container *hakurei.Container) { + container.SeccompFlags |= seccomp.AllowMultiarch + container.SeccompPresets |= seccomp.PresetStrict + container.Hostname = "hakurei-dbus" + container.CommandContext = p.CommandContext + if p.output != nil { + container.Stdout, container.Stderr = p.output, p.output + } + + if p.CmdF != nil { + p.CmdF(container) + } + + // these lib paths are unpredictable, so mount them first so they cannot cover anything + for _, name := range libPaths { + container.Bind(name, name, 0) + } + + // upstream bus directories + upstreamPaths := make([]string, 0, 2) + for _, addr := range [][]AddrEntry{p.final.SessionUpstream, p.final.SystemUpstream} { + for _, ent := range addr { + if ent.Method != "unix" { + continue + } + for _, pair := range ent.Values { + if pair[0] != "path" || !path.IsAbs(pair[1]) { + continue + } + upstreamPaths = append(upstreamPaths, path.Dir(pair[1])) + } + } + } + slices.Sort(upstreamPaths) + upstreamPaths = slices.Compact(upstreamPaths) + for _, name := range upstreamPaths { + container.Bind(name, name, 0) + } + + // parent directories of bind paths + sockDirPaths := make([]string, 0, 2) + if d := path.Dir(p.final.Session[1]); path.IsAbs(d) { + sockDirPaths = append(sockDirPaths, d) + } + if d := path.Dir(p.final.System[1]); path.IsAbs(d) { + sockDirPaths = append(sockDirPaths, d) + } + slices.Sort(sockDirPaths) + sockDirPaths = slices.Compact(sockDirPaths) + for _, name := range sockDirPaths { + container.Bind(name, name, hakurei.BindWritable) + } + + // xdg-dbus-proxy bin path + binPath := path.Dir(toolPath) + container.Bind(binPath, binPath, 0) + }, nil) + } + + if err := p.helper.Start(); err != nil { + cancel(err) + p.helper = nil + return err + } + + p.cancel, p.cause = cancel, func() error { return context.Cause(ctx) } + return nil +} + +var proxyClosed = errors.New("proxy closed") + +// Wait blocks until xdg-dbus-proxy exits and releases resources. +func (p *Proxy) Wait() error { + p.mu.RLock() + defer p.mu.RUnlock() + + p.pmu.RLock() + if p.helper == nil || p.cancel == nil || p.cause == nil { + p.pmu.RUnlock() + return errors.New("dbus: not started") + } + + errs := make([]error, 3) + + errs[0] = p.helper.Wait() + if errors.Is(errs[0], context.Canceled) && + errors.Is(p.cause(), proxyClosed) { + errs[0] = nil + } + p.pmu.RUnlock() + + // ensure socket removal so ephemeral directory is empty at revert + if err := os.Remove(p.final.Session[1]); err != nil && !errors.Is(err, os.ErrNotExist) { + errs[1] = err + } + if p.final.System[1] != "" { + if err := os.Remove(p.final.System[1]); err != nil && !errors.Is(err, os.ErrNotExist) { + errs[2] = err + } + } + + return errors.Join(errs...) +} + +// Close cancels the context passed to the helper instance attached to xdg-dbus-proxy. +func (p *Proxy) Close() { + p.pmu.Lock() + defer p.pmu.Unlock() + + if p.cancel == nil { + panic("dbus: not started") + } + p.cancel(proxyClosed) +} + +func argF(argsFd, statFd int) []string { + if statFd == -1 { + return []string{"--args=" + strconv.Itoa(argsFd)} + } else { + return []string{"--args=" + strconv.Itoa(argsFd), "--fd=" + strconv.Itoa(statFd)} + } +} |