118 lines
3.3 KiB
Go
118 lines
3.3 KiB
Go
package app
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import (
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"errors"
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"fmt"
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"io/fs"
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"path"
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"git.gensokyo.uk/security/fortify/internal/fmsg"
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"git.gensokyo.uk/security/fortify/internal/linux"
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"git.gensokyo.uk/security/fortify/internal/system"
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)
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const (
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pulseServer = "PULSE_SERVER"
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pulseCookie = "PULSE_COOKIE"
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home = "HOME"
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xdgConfigHome = "XDG_CONFIG_HOME"
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)
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var (
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ErrPulseCookie = errors.New("pulse cookie not present")
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ErrPulseSocket = errors.New("pulse socket not present")
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ErrPulseMode = errors.New("unexpected pulse socket mode")
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)
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func (seal *appSeal) sharePulse(os linux.System) error {
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if !seal.et.Has(system.EPulse) {
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return nil
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}
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// check PulseAudio directory presence (e.g. `/run/user/%d/pulse`)
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pd := path.Join(seal.RuntimePath, "pulse")
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ps := path.Join(pd, "native")
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if _, err := os.Stat(pd); err != nil {
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if !errors.Is(err, fs.ErrNotExist) {
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return fmsg.WrapErrorSuffix(err,
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fmt.Sprintf("cannot access PulseAudio directory %q:", pd))
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}
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return fmsg.WrapError(ErrPulseSocket,
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fmt.Sprintf("PulseAudio directory %q not found", pd))
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}
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// check PulseAudio socket permission (e.g. `/run/user/%d/pulse/native`)
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if s, err := os.Stat(ps); err != nil {
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if !errors.Is(err, fs.ErrNotExist) {
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return fmsg.WrapErrorSuffix(err,
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fmt.Sprintf("cannot access PulseAudio socket %q:", ps))
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}
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return fmsg.WrapError(ErrPulseSocket,
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fmt.Sprintf("PulseAudio directory %q found but socket does not exist", pd))
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} else {
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if m := s.Mode(); m&0o006 != 0o006 {
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return fmsg.WrapError(ErrPulseMode,
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fmt.Sprintf("unexpected permissions on %q:", ps), m)
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}
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}
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// hard link pulse socket into target-executable share
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psi := path.Join(seal.shareLocal, "pulse")
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p := path.Join(seal.sys.runtime, "pulse", "native")
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seal.sys.Link(ps, psi)
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seal.sys.bwrap.Bind(psi, p)
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seal.sys.bwrap.SetEnv[pulseServer] = "unix:" + p
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// publish current user's pulse cookie for target user
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if src, err := discoverPulseCookie(os); err != nil {
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return err
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} else {
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dst := path.Join(seal.share, "pulse-cookie")
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seal.sys.bwrap.SetEnv[pulseCookie] = dst
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seal.sys.CopyFile(dst, src)
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seal.sys.bwrap.Bind(dst, dst)
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}
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return nil
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}
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// discoverPulseCookie attempts various standard methods to discover the current user's PulseAudio authentication cookie
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func discoverPulseCookie(os linux.System) (string, error) {
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if p, ok := os.LookupEnv(pulseCookie); ok {
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return p, nil
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}
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// dotfile $HOME/.pulse-cookie
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if p, ok := os.LookupEnv(home); ok {
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p = path.Join(p, ".pulse-cookie")
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if s, err := os.Stat(p); err != nil {
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if !errors.Is(err, fs.ErrNotExist) {
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return p, fmsg.WrapErrorSuffix(err,
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fmt.Sprintf("cannot access PulseAudio cookie %q:", p))
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}
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// not found, try next method
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} else if !s.IsDir() {
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return p, nil
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}
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}
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// $XDG_CONFIG_HOME/pulse/cookie
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if p, ok := os.LookupEnv(xdgConfigHome); ok {
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p = path.Join(p, "pulse", "cookie")
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if s, err := os.Stat(p); err != nil {
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if !errors.Is(err, fs.ErrNotExist) {
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return p, fmsg.WrapErrorSuffix(err,
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fmt.Sprintf("cannot access PulseAudio cookie %q:", p))
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}
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// not found, try next method
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} else if !s.IsDir() {
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return p, nil
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}
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}
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return "", fmsg.WrapError(ErrPulseCookie,
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fmt.Sprintf("cannot locate PulseAudio cookie (tried $%s, $%s/pulse/cookie, $%s/.pulse-cookie)",
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pulseCookie, xdgConfigHome, home))
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}
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