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package dbus
import (
"errors"
"io"
"os/exec"
"path"
"path/filepath"
"strconv"
"strings"
"git.gensokyo.uk/security/fortify/helper"
"git.gensokyo.uk/security/fortify/helper/bwrap"
"git.gensokyo.uk/security/fortify/ldd"
)
// Start launches the D-Bus proxy and sets up the Wait method.
// ready should be buffered and must only be received from once.
func (p *Proxy) Start(ready chan error, output io.Writer, sandbox bool) error {
p.lock.Lock()
defer p.lock.Unlock()
if p.seal == nil {
return errors.New("proxy not sealed")
}
var (
h helper.Helper
cmd *exec.Cmd
argF = func(argsFD, statFD int) []string {
if statFD == -1 {
return []string{"--args=" + strconv.Itoa(argsFD)}
} else {
return []string{"--args=" + strconv.Itoa(argsFD), "--fd=" + strconv.Itoa(statFD)}
}
}
)
if !sandbox {
h = helper.New(p.seal, p.name, argF)
cmd = h.Unwrap()
// xdg-dbus-proxy does not need to inherit the environment
cmd.Env = []string{}
} else {
// look up absolute path if name is just a file name
toolPath := p.name
if filepath.Base(p.name) == p.name {
if s, err := exec.LookPath(p.name); err != nil {
return err
} else {
toolPath = s
}
}
// resolve libraries by parsing ldd output
var proxyDeps []*ldd.Entry
if toolPath != "/nonexistent-xdg-dbus-proxy" {
if l, err := ldd.Exec(toolPath); err != nil {
return err
} else {
proxyDeps = l
}
}
bc := &bwrap.Config{
Unshare: nil,
Hostname: "fortify-dbus",
Chdir: "/",
Clearenv: true,
NewSession: true,
DieWithParent: true,
}
// resolve proxy socket directories
bindTarget := make(map[string]struct{}, 2)
for _, ps := range []string{p.session[1], p.system[1]} {
if pd := path.Dir(ps); len(pd) > 0 {
if pd[0] == '/' {
bindTarget[pd] = struct{}{}
}
}
}
for k := range bindTarget {
bc.Bind(k, k, false, true)
}
roBindTarget := make(map[string]struct{}, 2+1+len(proxyDeps))
// xdb-dbus-proxy bin and dependencies
roBindTarget[path.Dir(toolPath)] = struct{}{}
for _, ent := range proxyDeps {
if path.IsAbs(ent.Path) {
roBindTarget[path.Dir(ent.Path)] = struct{}{}
}
if path.IsAbs(ent.Name) {
roBindTarget[path.Dir(ent.Name)] = struct{}{}
}
}
// resolve upstream bus directories
for _, as := range []string{p.session[0], p.system[0]} {
if len(as) > 0 && strings.HasPrefix(as, "unix:path=/") {
// leave / intact
roBindTarget[path.Dir(as[10:])] = struct{}{}
}
}
for k := range roBindTarget {
bc.Bind(k, k)
}
h = helper.MustNewBwrap(bc, toolPath, p.seal, argF, nil)
cmd = h.Unwrap()
p.bwrap = bc
}
if output != nil {
cmd.Stdout = output
cmd.Stderr = output
}
if err := h.StartNotify(ready); err != nil {
return err
}
p.helper = h
return nil
}
// Wait waits for xdg-dbus-proxy to exit or fault.
func (p *Proxy) Wait() error {
p.lock.RLock()
defer p.lock.RUnlock()
if p.helper == nil {
return errors.New("proxy not started")
}
return p.helper.Wait()
}
// Close closes the status file descriptor passed to xdg-dbus-proxy, causing it to stop.
func (p *Proxy) Close() error {
return p.helper.Close()
}
|
