cmd: shim and init into separate binaries

This change also fixes a deadlock when shim fails to connect and complete the setup.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

1 files changed, 0 insertions, 179 deletions

diff --git a/internal/shim/main.go b/internal/shim/main.go
deleted file mode 100644
index 52a8fa9e..00000000
--- a/internal/shim/main.go
+++ /dev/null
@@ -1,179 +0,0 @@
-package shim
-
-import (
-	"encoding/gob"
-	"errors"
-	"flag"
-	"net"
-	"os"
-	"path"
-	"strconv"
-	"syscall"
-
-	"git.ophivana.moe/security/fortify/helper"
-	"git.ophivana.moe/security/fortify/internal/fmsg"
-	init0 "git.ophivana.moe/security/fortify/internal/init"
-)
-
-// everything beyond this point runs as target user
-// proceed with caution!
-
-func doShim(socket string) {
-	fmsg.SetPrefix("shim")
-
-	// re-exec
-	if len(os.Args) > 0 && os.Args[0] != "fortify" && path.IsAbs(os.Args[0]) {
-		if err := syscall.Exec(os.Args[0], []string{"fortify", "shim"}, os.Environ()); err != nil {
-			fmsg.Println("cannot re-exec self:", err)
-			// continue anyway
-		}
-	}
-
-	// dial setup socket
-	var conn *net.UnixConn
-	if c, err := net.DialUnix("unix", nil, &net.UnixAddr{Name: socket, Net: "unix"}); err != nil {
-		fmsg.Fatal("cannot dial setup socket:", err)
-		panic("unreachable")
-	} else {
-		conn = c
-	}
-
-	// decode payload gob stream
-	var payload Payload
-	if err := gob.NewDecoder(conn).Decode(&payload); err != nil {
-		fmsg.Fatal("cannot decode shim payload:", err)
-	} else {
-		// sharing stdout with parent
-		// USE WITH CAUTION
-		fmsg.SetVerbose(payload.Verbose)
-	}
-
-	if payload.Bwrap == nil {
-		fmsg.Fatal("bwrap config not supplied")
-	}
-
-	// receive wayland fd over socket
-	wfd := -1
-	if payload.WL {
-		if fd, err := receiveWLfd(conn); err != nil {
-			fmsg.Fatal("cannot receive wayland fd:", err)
-		} else {
-			wfd = fd
-		}
-	}
-
-	// close setup socket
-	if err := conn.Close(); err != nil {
-		fmsg.Println("cannot close setup socket:", err)
-		// not fatal
-	}
-
-	var ic init0.Payload
-
-	// resolve argv0
-	ic.Argv = payload.Argv
-	if len(ic.Argv) > 0 {
-		// looked up from $PATH by parent
-		ic.Argv0 = payload.Exec[2]
-	} else {
-		// no argv, look up shell instead
-		var ok bool
-		if ic.Argv0, ok = os.LookupEnv("SHELL"); !ok {
-			fmsg.Fatal("no command was specified and $SHELL was unset")
-		}
-
-		ic.Argv = []string{ic.Argv0}
-	}
-
-	conf := payload.Bwrap
-
-	var extraFiles []*os.File
-
-	// pass wayland fd
-	if wfd != -1 {
-		if f := os.NewFile(uintptr(wfd), "wayland"); f != nil {
-			ic.WL = 3 + len(extraFiles)
-			extraFiles = append(extraFiles, f)
-		}
-	} else {
-		ic.WL = -1
-	}
-
-	// share config pipe
-	if r, w, err := os.Pipe(); err != nil {
-		fmsg.Fatal("cannot pipe:", err)
-	} else {
-		conf.SetEnv[init0.EnvInit] = strconv.Itoa(3 + len(extraFiles))
-		extraFiles = append(extraFiles, r)
-
-		fmsg.VPrintln("transmitting config to init")
-		go func() {
-			// stream config to pipe
-			if err = gob.NewEncoder(w).Encode(&ic); err != nil {
-				fmsg.Fatal("cannot transmit init config:", err)
-			}
-		}()
-	}
-
-	helper.BubblewrapName = payload.Exec[1] // resolved bwrap path by parent
-	if b, err := helper.NewBwrap(conf, nil, payload.Exec[0], func(int, int) []string { return []string{"init"} }); err != nil {
-		fmsg.Fatal("malformed sandbox config:", err)
-	} else {
-		cmd := b.Unwrap()
-		cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
-		cmd.ExtraFiles = extraFiles
-
-		if fmsg.Verbose() {
-			fmsg.VPrintln("bwrap args:", conf.Args())
-		}
-
-		// run and pass through exit code
-		if err = b.Start(); err != nil {
-			fmsg.Fatal("cannot start target process:", err)
-		} else if err = b.Wait(); err != nil {
-			fmsg.VPrintln("wait:", err)
-		}
-		if b.Unwrap().ProcessState != nil {
-			fmsg.Exit(b.Unwrap().ProcessState.ExitCode())
-		} else {
-			fmsg.Exit(127)
-		}
-	}
-}
-
-func receiveWLfd(conn *net.UnixConn) (int, error) {
-	oob := make([]byte, syscall.CmsgSpace(4)) // single fd
-
-	if _, oobn, _, _, err := conn.ReadMsgUnix(nil, oob); err != nil {
-		return -1, err
-	} else if len(oob) != oobn {
-		return -1, errors.New("invalid message length")
-	}
-
-	var msg syscall.SocketControlMessage
-	if messages, err := syscall.ParseSocketControlMessage(oob); err != nil {
-		return -1, err
-	} else if len(messages) != 1 {
-		return -1, errors.New("unexpected message count")
-	} else {
-		msg = messages[0]
-	}
-
-	if fds, err := syscall.ParseUnixRights(&msg); err != nil {
-		return -1, err
-	} else if len(fds) != 1 {
-		return -1, errors.New("unexpected fd count")
-	} else {
-		return fds[0], nil
-	}
-}
-
-// Try runs shim and stops execution if FORTIFY_SHIM is set.
-func Try() {
-	if args := flag.Args(); len(args) == 1 && args[0] == "shim" {
-		if s, ok := os.LookupEnv(EnvShim); ok {
-			doShim(s)
-			panic("unreachable")
-		}
-	}
-}