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package system
import (
"bytes"
"errors"
"os"
"strings"
"sync"
"git.ophivana.moe/security/fortify/dbus"
"git.ophivana.moe/security/fortify/internal/fmsg"
)
var (
ErrDBusConfig = errors.New("dbus config not supplied")
)
func (sys *I) MustProxyDBus(sessionPath string, session *dbus.Config, systemPath string, system *dbus.Config) *I {
if _, err := sys.ProxyDBus(session, system, sessionPath, systemPath); err != nil {
panic(err.Error())
} else {
return sys
}
}
func (sys *I) ProxyDBus(session, system *dbus.Config, sessionPath, systemPath string) (func(f func(msgbuf []string)), error) {
d := new(DBus)
// used by waiting goroutine to notify process exit
d.done = make(chan struct{})
// session bus is mandatory
if session == nil {
return nil, fmsg.WrapError(ErrDBusConfig,
"attempted to seal message bus proxy without session bus config")
}
// system bus is optional
d.system = system == nil
// upstream address, downstream socket path
var sessionBus, systemBus [2]string
// resolve upstream bus addresses
sessionBus[0], systemBus[0] = dbus.Address()
// set paths from caller
sessionBus[1], systemBus[1] = sessionPath, systemPath
// create proxy instance
d.proxy = dbus.New(sessionBus, systemBus)
defer func() {
if fmsg.Verbose() && d.proxy.Sealed() {
fmsg.VPrintln("sealed session proxy", session.Args(sessionBus))
if system != nil {
fmsg.VPrintln("sealed system proxy", system.Args(systemBus))
}
fmsg.VPrintln("message bus proxy final args:", d.proxy)
}
}()
// queue operation
sys.ops = append(sys.ops, d)
// seal dbus proxy
d.out = &scanToFmsg{msg: new(strings.Builder)}
return d.out.F, fmsg.WrapErrorSuffix(d.proxy.Seal(session, system),
"cannot seal message bus proxy:")
}
type DBus struct {
proxy *dbus.Proxy
out *scanToFmsg
// whether system bus proxy is enabled
system bool
// notification from goroutine waiting for dbus.Proxy
done chan struct{}
}
func (d *DBus) Type() Enablement {
return Process
}
func (d *DBus) apply(_ *I) error {
fmsg.VPrintf("session bus proxy on %q for upstream %q", d.proxy.Session()[1], d.proxy.Session()[0])
if d.system {
fmsg.VPrintf("system bus proxy on %q for upstream %q", d.proxy.System()[1], d.proxy.System()[0])
}
// ready channel passed to dbus package
ready := make(chan error, 1)
// background dbus proxy start
if err := d.proxy.Start(ready, d.out, true); err != nil {
return fmsg.WrapErrorSuffix(err,
"cannot start message bus proxy:")
}
fmsg.VPrintln("starting message bus proxy:", d.proxy)
if fmsg.Verbose() { // save the extra bwrap arg build when verbose logging is off
fmsg.VPrintln("message bus proxy bwrap args:", d.proxy.Bwrap())
}
// background wait for proxy instance and notify completion
go func() {
if err := d.proxy.Wait(); err != nil {
fmsg.Println("message bus proxy exited with error:", err)
go func() { ready <- err }()
} else {
fmsg.VPrintln("message bus proxy exit")
}
// ensure socket removal so ephemeral directory is empty at revert
if err := os.Remove(d.proxy.Session()[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
fmsg.Println("cannot remove dangling session bus socket:", err)
}
if d.system {
if err := os.Remove(d.proxy.System()[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
fmsg.Println("cannot remove dangling system bus socket:", err)
}
}
// notify proxy completion
close(d.done)
}()
// ready is not nil if the proxy process faulted
if err := <-ready; err != nil {
// note that err here is either an I/O error or a predetermined unexpected behaviour error
return fmsg.WrapErrorSuffix(err,
"message bus proxy fault after start:")
}
fmsg.VPrintln("message bus proxy ready")
return nil
}
func (d *DBus) revert(_ *I, _ *Criteria) error {
// criteria ignored here since dbus is always process-scoped
fmsg.VPrintln("terminating message bus proxy")
if err := d.proxy.Close(); err != nil {
if errors.Is(err, os.ErrClosed) {
return fmsg.WrapError(err,
"message bus proxy already closed")
} else {
return fmsg.WrapErrorSuffix(err,
"cannot stop message bus proxy:")
}
}
// block until proxy wait returns
<-d.done
return nil
}
func (d *DBus) Is(o Op) bool {
d0, ok := o.(*DBus)
return ok && d0 != nil &&
((d.proxy == nil && d0.proxy == nil) ||
(d.proxy != nil && d0.proxy != nil && d.proxy.String() == d0.proxy.String()))
}
func (d *DBus) Path() string {
return "(dbus proxy)"
}
func (d *DBus) String() string {
return d.proxy.String()
}
type scanToFmsg struct {
msg *strings.Builder
msgbuf []string
mu sync.RWMutex
}
func (s *scanToFmsg) Write(p []byte) (n int, err error) {
s.mu.Lock()
defer s.mu.Unlock()
return s.write(p, 0)
}
func (s *scanToFmsg) write(p []byte, a int) (int, error) {
if i := bytes.IndexByte(p, '\n'); i == -1 {
n, _ := s.msg.Write(p)
return a + n, nil
} else {
n, _ := s.msg.Write(p[:i])
s.msgbuf = append(s.msgbuf, s.msg.String())
s.msg.Reset()
return s.write(p[i+1:], a+n+1)
}
}
func (s *scanToFmsg) F(f func(msgbuf []string)) {
s.mu.RLock()
f(s.msgbuf)
s.mu.RUnlock()
}
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