fortify/launcher.go

73 lines
1.5 KiB
Go

package main
import (
"bytes"
"encoding/base64"
"encoding/gob"
"fmt"
"os"
"strings"
"syscall"
)
const (
// hidden path for main to act as a launcher
egoLauncher = "EGO_LAUNCHER"
)
// hidden launcher path
func tryLauncher() {
if printVersion {
if r, ok := os.LookupEnv(egoLauncher); ok {
// egoLauncher variable contains launcher payload
dec := base64.NewDecoder(base64.StdEncoding, strings.NewReader(r))
var argv []string
if err := gob.NewDecoder(dec).Decode(&argv); err != nil {
fmt.Println("Error decoding launcher payload:", err)
os.Exit(1)
}
if err := os.Unsetenv(egoLauncher); err != nil {
fmt.Println("Error unsetting launcher payload:", err)
// not fatal, do not fail
}
var p string
if len(argv) > 0 {
if p, ok = which(argv[0]); !ok {
fmt.Printf("Did not find '%s' in PATH\n", argv[0])
os.Exit(1)
}
} else {
if p, ok = os.LookupEnv("SHELL"); !ok {
fmt.Println("No command was specified and $SHELL was unset")
os.Exit(1)
}
}
if err := syscall.Exec(p, argv, os.Environ()); err != nil {
fmt.Println("Error executing launcher payload:", err)
os.Exit(1)
}
// unreachable
os.Exit(1)
return
}
}
}
func launcherPayloadEnv() string {
r := &bytes.Buffer{}
enc := base64.NewEncoder(base64.StdEncoding, r)
if err := gob.NewEncoder(enc).Encode(command); err != nil {
fatal("Error encoding launcher payload:", err)
}
_ = enc.Close()
return egoLauncher + "=" + r.String()
}