Added hkexpasswd util; moved minimal term stuff into hkexauth.go

README.md

@@ -18,10 +18,10 @@
 
 --
 
-This is a drop-in replacement for the golang/pkg/net facilities
-(net.Dial(), net.Listen(), net.Accept() and net.Conn type) using the
+Package herradurakex is a drop-in replacement for golang/pkg/net facilities
+(net.Dial(), net.Listen(), net.Accept() and the net.Conn type) using the
 experimental HerraduraKEx 'secure' key exchange algorithm, first released at
-github.com/Caume/HerraduraKEx
+(Omar Elejandro Herrera Reyna's github page)[github.com/Caume/HerraduraKEx].
 
 One can simply replace calls to net.Dial() with hkex.Dial(), and likewise
 net.Listen() with hkex.Listen(), to obtain connections (hkex.Conn) conforming

demo/client/client.go

@@ -13,7 +13,6 @@ import (
 
 	hkex "blitter.com/herradurakex"
 	isatty "github.com/mattn/go-isatty"
-	"golang.org/x/sys/unix"
 )
 
 type cmdSpec struct {
@@ -69,16 +68,17 @@ func main() {
 		panic(err)
 	}
 	defer conn.Close()
+	// From this point on, conn is a secure encrypted channel
 
 	// Set stdin in raw mode if it's an interactive session
 	// TODO: send flag to server side indicating this
 	//  affects shell command used
 	if isatty.IsTerminal(os.Stdin.Fd()) {
-		oldState, err := MakeRaw(int(os.Stdin.Fd()))
+		oldState, err := hkex.MakeRaw(int(os.Stdin.Fd()))
 		if err != nil {
 			panic(err)
 		}
-		defer func() { _ = Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.
+		defer func() { _ = hkex.Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.
 	} else {
 		log.Println("NOT A TTY")
 	}
@@ -108,7 +108,8 @@ func main() {
 
 	if len(authCookie) == 0 {
 		fmt.Printf("Gimme cookie:")
-		ab, err := ReadPassword(int(os.Stdin.Fd()))
+		ab, err := hkex.ReadPassword(int(os.Stdin.Fd()))
+		fmt.Printf("\r\n")
 		if err != nil {
 			panic(err)
 		}
@@ -179,124 +180,3 @@ func main() {
 	// Wait until both stdin and stdout goroutines finish
 	wg.Wait()
 }
-
-/* ------------- minimal terminal APIs brought in from ssh/terminal
- * (they have no real business being there as they aren't specific to
- * ssh, but as of v1.10, early 2018, core go stdlib hasn't yet done
- * the planned terminal lib reorgs.)
- * -------------
- */
-
-// From github.com/golang/crypto/blob/master/ssh/terminal/util_linux.go
-const ioctlReadTermios = unix.TCGETS
-const ioctlWriteTermios = unix.TCSETS
-
-// From github.com/golang/crypto/blob/master/ssh/terminal/util.go
-// State contains the state of a terminal.
-type State struct {
-	termios unix.Termios
-}
-
-// MakeRaw put the terminal connected to the given file descriptor into raw
-// mode and returns the previous state of the terminal so that it can be
-// restored.
-func MakeRaw(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	if err != nil {
-		return nil, err
-	}
-
-	oldState := State{termios: *termios}
-
-	// This attempts to replicate the behaviour documented for cfmakeraw in
-	// the termios(3) manpage.
-	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
-	termios.Oflag &^= unix.OPOST
-	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
-	termios.Cflag &^= unix.CSIZE | unix.PARENB
-	termios.Cflag |= unix.CS8
-	termios.Cc[unix.VMIN] = 1
-	termios.Cc[unix.VTIME] = 0
-	if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, termios); err != nil {
-		return nil, err
-	}
-
-	return &oldState, nil
-}
-
-// GetState returns the current state of a terminal which may be useful to
-// restore the terminal after a signal.
-func GetState(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	if err != nil {
-		return nil, err
-	}
-
-	return &State{termios: *termios}, nil
-}
-
-// Restore restores the terminal connected to the given file descriptor to a
-// previous state.
-func Restore(fd int, state *State) error {
-	return unix.IoctlSetTermios(fd, ioctlWriteTermios, &state.termios)
-}
-
-// ReadPassword reads a line of input from a terminal without local echo.  This
-// is commonly used for inputting passwords and other sensitive data. The slice
-// returned does not include the \n.
-func ReadPassword(fd int) ([]byte, error) {
-	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	if err != nil {
-		return nil, err
-	}
-
-	newState := *termios
-	newState.Lflag &^= unix.ECHO
-	newState.Lflag |= unix.ICANON | unix.ISIG
-	newState.Iflag |= unix.ICRNL
-	if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, &newState); err != nil {
-		return nil, err
-	}
-
-	defer func() {
-		unix.IoctlSetTermios(fd, ioctlWriteTermios, termios)
-	}()
-
-	return readPasswordLine(passwordReader(fd))
-}
-
-// passwordReader is an io.Reader that reads from a specific file descriptor.
-type passwordReader int
-
-func (r passwordReader) Read(buf []byte) (int, error) {
-	return unix.Read(int(r), buf)
-}
-
-// readPasswordLine reads from reader until it finds \n or io.EOF.
-// The slice returned does not include the \n.
-// readPasswordLine also ignores any \r it finds.
-func readPasswordLine(reader io.Reader) ([]byte, error) {
-	var buf [1]byte
-	var ret []byte
-
-	for {
-		n, err := reader.Read(buf[:])
-		if n > 0 {
-			switch buf[0] {
-			case '\n':
-				return ret, nil
-			case '\r':
-				// remove \r from passwords on Windows
-			default:
-				ret = append(ret, buf[0])
-			}
-			continue
-		}
-		if err != nil {
-			if err == io.EOF && len(ret) > 0 {
-				return ret, nil
-			}
-			return ret, err
-		}
-	}
-}

demo/hkexpasswd/hkexpasswd.go

@@ -0,0 +1,128 @@
+// Util to generate/store passwords for users in a file akin to /etc/passwd
+// suitable for the demo hkexsh server, using bcrypt.
+package main
+
+import (
+	"bytes"
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/user"
+
+	hkex "blitter.com/herradurakex"
+	"github.com/jameskeane/bcrypt"
+)
+
+func main() {
+	var pfName string
+	var newpw string
+	var confirmpw string
+	var userName string
+
+	flag.StringVar(&userName, "u", "", "username")
+	flag.StringVar(&pfName, "f", "/etc/hkexsh.passwd", "passwd file")
+	flag.Parse()
+
+	var uname string
+	if len(userName) == 0 {
+		log.Println("specify username with -u")
+		os.Exit(1)
+	}
+
+	u, err := user.Lookup(userName)
+	if err != nil {
+		log.Printf("Invalid user %s\n", userName)
+		log.Fatal(err)
+	}
+	uname = u.Username
+
+	fmt.Printf("New Password:")
+	ab, err := hkex.ReadPassword(int(os.Stdin.Fd()))
+	fmt.Printf("\r\n")
+	if err != nil {
+		log.Fatal(err)
+		os.Exit(1)
+	}
+	newpw = string(ab)
+
+	fmt.Printf("Confirm:")
+	ab, err = hkex.ReadPassword(int(os.Stdin.Fd()))
+	fmt.Printf("\r\n")
+	if err != nil {
+		log.Fatal(err)
+		os.Exit(1)
+	}
+	confirmpw = string(ab)
+
+	if confirmpw != newpw {
+		log.Println("New passwords do not match.")
+		os.Exit(1)
+	}
+
+	// generate a random salt with specific rounds of complexity
+	// (default in jameskeane/bcrypt is 12 but we'll be explicit here)
+	salt, err := bcrypt.Salt(12)
+	if err != nil {
+		fmt.Println("ERROR: bcrypt.Salt() failed.")
+		os.Exit(2)
+	}
+
+	// hash and verify a password with explicit (random) salt
+	hash, err := bcrypt.Hash(newpw, salt)
+	if err != nil || !bcrypt.Match(newpw, hash) {
+		fmt.Println("ERROR: bcrypt.Match() failed.")
+		log.Fatal(err)
+	}
+	//fmt.Println("Salt:", salt, "Hash:", hash)
+
+	b, err := ioutil.ReadFile(pfName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	r := csv.NewReader(bytes.NewReader(b))
+
+	r.Comma = ':'
+	r.Comment = '#'
+	r.FieldsPerRecord = 4 // username:salt:authCookie:disallowedCmdList (a,b,...)
+
+	records, err := r.ReadAll()
+	if err != nil {
+		log.Fatal(err)
+	}
+	for i, _ := range records {
+		//fmt.Println(records[i])
+		if records[i][0] == uname {
+			records[i][1] = salt
+			records[i][2] = hash
+		}
+		//// csv lib doesn't preserve comment in record, so put it back
+		//if records[i][0][0] == '!' {
+		//	records[i][0] = "#" + records[i][0]
+		//}
+	}
+
+	outFile, err := ioutil.TempFile("", "hkexsh-passwd")
+	if err != nil {
+		log.Fatal(err)
+	}
+	w := csv.NewWriter(outFile)
+	w.Comma = ':'
+	//w.FieldsPerRecord = 4 // username:salt:authCookie:disallowedCmdList (a,b,...)
+	w.Write([]string{"#username", "salt", "authCookie", "disallowedCmdList"})
+	w.WriteAll(records)
+	if err = w.Error(); err != nil {
+		log.Fatal(err)
+	}
+
+	err = os.Remove(pfName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = os.Rename(outFile.Name(), pfName)
+	if err != nil {
+		log.Fatal(err)
+	}
+}

demo/hkexpasswd/hkexpasswd.go~

@@ -0,0 +1,128 @@
+// Util to generate/store passwords for users in a file akin to /etc/passwd
+// suitable for the demo hkexsh server, using bcrypt.
+package main
+
+import (
+	"bytes"
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/user"
+
+	hkex "blitter.com/herradurakex"
+	"github.com/jameskeane/bcrypt"
+)
+
+func main() {
+	var pfName string
+	var newpw string
+	var confirmpw string
+	var userName string
+
+	flag.StringVar(&userName, "u", "", "username")
+	flag.StringVar(&pfName, "f", "/etc/hkexsh.passwd", "passwd file")
+	flag.Parse()
+
+	var uname string
+	if len(userName) == 0 {
+		log.Println("specify username with -u")
+		os.Exit(1)
+	}
+
+	u, err := user.Lookup(userName)
+	if err != nil {
+		log.Printf("Invalid user %s\n", userName)
+		log.Fatal(err)
+	}
+	uname = u.Username
+
+	fmt.Printf("New Password:")
+	ab, err := hkex.ReadPassword(int(os.Stdin.Fd()))
+	fmt.Printf("\r\n")
+	if err != nil {
+		log.Fatal(err)
+		os.Exit(1)
+	}
+	newpw = string(ab)
+
+	fmt.Printf("Confirm:")
+	ab, err = hkex.ReadPassword(int(os.Stdin.Fd()))
+	fmt.Printf("\r\n")
+	if err != nil {
+		log.Fatal(err)
+		os.Exit(1)
+	}
+	confirmpw = string(ab)
+
+	if confirmpw != newpw {
+		log.Println("New passwords do not match.")
+		os.Exit(1)
+	}
+
+	// generate a random salt with specific rounds of complexity
+	// (default in jameskeane/bcrypt is 12 but we'll be explicit here)
+	salt, err := bcrypt.Salt(12)
+	if err != nil {
+		fmt.Println("ERROR: bcrypt.Salt() failed.")
+		os.Exit(2)
+	}
+
+	// hash and verify a password with explicit (random) salt
+	hash, err := bcrypt.Hash(newpw, salt)
+	if err != nil || !bcrypt.Match(newpw, hash) {
+		fmt.Println("ERROR: bcrypt.Match() failed.")
+		log.Fatal(err)
+	}
+	//fmt.Println("Salt:", salt, "Hash:", hash)
+
+	b, err := ioutil.ReadFile(pfName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	r := csv.NewReader(bytes.NewReader(b))
+
+	r.Comma = ':'
+	r.Comment = '#'
+	r.FieldsPerRecord = 4 // username:salt:authCookie:disallowedCmdList (a,b,...)
+
+	records, err := r.ReadAll()
+	if err != nil {
+		log.Fatal(err)
+	}
+	for i, _ := range records {
+		fmt.Println(records[i])
+		if records[i][0] == uname {
+			records[i][1] = salt
+			records[i][2] = hash
+		}
+		//// csv lib doesn't preserve comment in record, so put it back
+		//if records[i][0][0] == '!' {
+		//	records[i][0] = "#" + records[i][0]
+		//}
+	}
+
+	outFile, err := ioutil.TempFile("", "hkexsh-passwd")
+	if err != nil {
+		log.Fatal(err)
+	}
+	w := csv.NewWriter(outFile)
+	w.Comma = ':'
+	//w.FieldsPerRecord = 4 // username:salt:authCookie:disallowedCmdList (a,b,...)
+	w.Write([]string{"#username", "salt", "authCookie", "disallowedCmdList"})
+	w.WriteAll(records)
+	if err = w.Error(); err != nil {
+		log.Fatal(err)
+	}
+
+	err = os.Remove(pfName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = os.Rename(outFile.Name(), pfName)
+	if err != nil {
+		log.Fatal(err)
+	}
+}

demo/server/server.go

@@ -13,6 +13,7 @@ import (
 	"syscall"
 
 	hkex "blitter.com/herradurakex"
+	"blitter.com/spinsult"
 	"github.com/kr/pty"
 )
 
@@ -109,8 +110,7 @@ func runShellAs(who string, cmd string, interactive bool, conn hkex.Conn) (err e
 }
 
 func rejectUserMsg() string {
-		// TODO: Use Shakespeare insult generator. :p
-		return "Invalid user\r\n"
+	return "Begone, " + spinsult.GetSentence() + "\r\n"
 }
 
 // Demo of a simple server that listens and spawns goroutines for each
@@ -201,9 +201,9 @@ func main() {
 
 			valid, allowedCmds := hkex.AuthUser(string(rec.who), string(rec.authCookie), "/etc/hkexsh.passwd")
 			if !valid {
-					log.Println("Invalid user", string(rec.who))
-					c.Write([]byte(rejectUserMsg()))
-					return
+				log.Println("Invalid user", string(rec.who))
+				c.Write([]byte(rejectUserMsg()))
+				return
 			}
 			log.Printf("[allowedCmds:%s]\n", allowedCmds)
 

hkexauth.go

@@ -10,9 +10,12 @@ import (
 	"io/ioutil"
 	"log"
 	"runtime"
+
+	"github.com/jameskeane/bcrypt"
+	"golang.org/x/sys/unix"
 )
 
-func AuthUser(username string, authcookie string, fname string) (valid bool, allowedCmds string) {
+func AuthUser(username string, auth string, fname string) (valid bool, allowedCmds string) {
 	b, _ := ioutil.ReadFile(fname)
 	r := csv.NewReader(bytes.NewReader(b))
 
@@ -21,7 +24,7 @@ func AuthUser(username string, authcookie string, fname string) (valid bool, all
 
 	r.Comma = ':'
 	r.Comment = '#'
-	r.FieldsPerRecord = 3 // username:authCookie:disallowedCmdList (a,b,...)
+	r.FieldsPerRecord = 4 // username:salt:authCookie:disallowedCmdList (a,b,...)
 	for {
 		record, err := r.Read()
 		if err == io.EOF {
@@ -31,9 +34,11 @@ func AuthUser(username string, authcookie string, fname string) (valid bool, all
 			log.Fatal(err)
 		}
 
-		if username == record[0] &&
-			authcookie == record[1] {
-			valid = true
+		if username == record[0] {
+			tmp, _ := bcrypt.Hash(auth, record[1])
+			if tmp == record[2] {
+				valid = true
+			}
 			break
 		}
 
@@ -41,3 +46,124 @@ func AuthUser(username string, authcookie string, fname string) (valid bool, all
 	}
 	return
 }
+
+/* ------------- minimal terminal APIs brought in from ssh/terminal
+ * (they have no real business being there as they aren't specific to
+ * ssh, but as of v1.10, early 2018, core go stdlib hasn't yet done
+ * the planned terminal lib reorgs.)
+ * -------------
+ */
+
+// From github.com/golang/crypto/blob/master/ssh/terminal/util_linux.go
+const ioctlReadTermios = unix.TCGETS
+const ioctlWriteTermios = unix.TCSETS
+
+// From github.com/golang/crypto/blob/master/ssh/terminal/util.go
+// State contains the state of a terminal.
+type State struct {
+	termios unix.Termios
+}
+
+// MakeRaw put the terminal connected to the given file descriptor into raw
+// mode and returns the previous state of the terminal so that it can be
+// restored.
+func MakeRaw(fd int) (*State, error) {
+	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
+	if err != nil {
+		return nil, err
+	}
+
+	oldState := State{termios: *termios}
+
+	// This attempts to replicate the behaviour documented for cfmakeraw in
+	// the termios(3) manpage.
+	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
+	termios.Oflag &^= unix.OPOST
+	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
+	termios.Cflag &^= unix.CSIZE | unix.PARENB
+	termios.Cflag |= unix.CS8
+	termios.Cc[unix.VMIN] = 1
+	termios.Cc[unix.VTIME] = 0
+	if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, termios); err != nil {
+		return nil, err
+	}
+
+	return &oldState, nil
+}
+
+// GetState returns the current state of a terminal which may be useful to
+// restore the terminal after a signal.
+func GetState(fd int) (*State, error) {
+	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
+	if err != nil {
+		return nil, err
+	}
+
+	return &State{termios: *termios}, nil
+}
+
+// Restore restores the terminal connected to the given file descriptor to a
+// previous state.
+func Restore(fd int, state *State) error {
+	return unix.IoctlSetTermios(fd, ioctlWriteTermios, &state.termios)
+}
+
+// ReadPassword reads a line of input from a terminal without local echo.  This
+// is commonly used for inputting passwords and other sensitive data. The slice
+// returned does not include the \n.
+func ReadPassword(fd int) ([]byte, error) {
+	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
+	if err != nil {
+		return nil, err
+	}
+
+	newState := *termios
+	newState.Lflag &^= unix.ECHO
+	newState.Lflag |= unix.ICANON | unix.ISIG
+	newState.Iflag |= unix.ICRNL
+	if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, &newState); err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		unix.IoctlSetTermios(fd, ioctlWriteTermios, termios)
+	}()
+
+	return readPasswordLine(passwordReader(fd))
+}
+
+// passwordReader is an io.Reader that reads from a specific file descriptor.
+type passwordReader int
+
+func (r passwordReader) Read(buf []byte) (int, error) {
+	return unix.Read(int(r), buf)
+}
+
+// readPasswordLine reads from reader until it finds \n or io.EOF.
+// The slice returned does not include the \n.
+// readPasswordLine also ignores any \r it finds.
+func readPasswordLine(reader io.Reader) ([]byte, error) {
+	var buf [1]byte
+	var ret []byte
+
+	for {
+		n, err := reader.Read(buf[:])
+		if n > 0 {
+			switch buf[0] {
+			case '\n':
+				return ret, nil
+			case '\r':
+				// remove \r from passwords on Windows
+			default:
+				ret = append(ret, buf[0])
+			}
+			continue
+		}
+		if err != nil {
+			if err == io.EOF && len(ret) > 0 {
+				return ret, nil
+			}
+			return ret, err
+		}
+	}
+}