From 51e2106eed1cea199c802d2a49e91e2491b02056 Mon Sep 17 00:00:00 2001 From: raz-varren Date: Mon, 15 Apr 2019 10:47:12 -0700 Subject: [PATCH] Add SCRAM-SHA-256 authentication to this library (#833) Add SCRAM-SHA-256 authentication to this library --- conn.go | 52 +++++++++- scram/scram.go | 264 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 315 insertions(+), 1 deletion(-) create mode 100644 scram/scram.go diff --git a/conn.go b/conn.go index df2dab22..62551a14 100644 --- a/conn.go +++ b/conn.go @@ -4,6 +4,7 @@ import ( "bufio" "context" "crypto/md5" + "crypto/sha256" "database/sql" "database/sql/driver" "encoding/binary" @@ -21,6 +22,7 @@ import ( "unicode" "github.com/lib/pq/oid" + "github.com/lib/pq/scram" ) // Common error types @@ -958,7 +960,6 @@ func (cn *conn) recv() (t byte, r *readBuf) { if err != nil { panic(err) } - switch t { case 'E': panic(parseError(r)) @@ -1129,6 +1130,55 @@ func (cn *conn) auth(r *readBuf, o values) { if r.int32() != 0 { errorf("unexpected authentication response: %q", t) } + case 10: + sc := scram.NewClient(sha256.New, o["user"], o["password"]) + sc.Step(nil) + if sc.Err() != nil { + errorf("SCRAM-SHA-256 error: %s", sc.Err().Error()) + } + scOut := sc.Out() + + w := cn.writeBuf('p') + w.string("SCRAM-SHA-256") + w.int32(len(scOut)) + w.bytes(scOut) + cn.send(w) + + t, r := cn.recv() + if t != 'R' { + errorf("unexpected password response: %q", t) + } + + if r.int32() != 11 { + errorf("unexpected authentication response: %q", t) + } + + nextStep := r.next(len(*r)) + sc.Step(nextStep) + if sc.Err() != nil { + errorf("SCRAM-SHA-256 error: %s", sc.Err().Error()) + } + + scOut = sc.Out() + w = cn.writeBuf('p') + w.bytes(scOut) + cn.send(w) + + t, r = cn.recv() + if t != 'R' { + errorf("unexpected password response: %q", t) + } + + if r.int32() != 12 { + errorf("unexpected authentication response: %q", t) + } + + nextStep = r.next(len(*r)) + sc.Step(nextStep) + if sc.Err() != nil { + errorf("SCRAM-SHA-256 error: %s", sc.Err().Error()) + } + default: errorf("unknown authentication response: %d", code) } diff --git a/scram/scram.go b/scram/scram.go new file mode 100644 index 00000000..5d0358f8 --- /dev/null +++ b/scram/scram.go @@ -0,0 +1,264 @@ +// Copyright (c) 2014 - Gustavo Niemeyer +// +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are met: +// +// 1. Redistributions of source code must retain the above copyright notice, this +// list of conditions and the following disclaimer. +// 2. Redistributions in binary form must reproduce the above copyright notice, +// this list of conditions and the following disclaimer in the documentation +// and/or other materials provided with the distribution. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND +// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR +// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// Pacakage scram implements a SCRAM-{SHA-1,etc} client per RFC5802. +// +// http://tools.ietf.org/html/rfc5802 +// +package scram + +import ( + "bytes" + "crypto/hmac" + "crypto/rand" + "encoding/base64" + "fmt" + "hash" + "strconv" + "strings" +) + +// Client implements a SCRAM-* client (SCRAM-SHA-1, SCRAM-SHA-256, etc). +// +// A Client may be used within a SASL conversation with logic resembling: +// +// var in []byte +// var client = scram.NewClient(sha1.New, user, pass) +// for client.Step(in) { +// out := client.Out() +// // send out to server +// in := serverOut +// } +// if client.Err() != nil { +// // auth failed +// } +// +type Client struct { + newHash func() hash.Hash + + user string + pass string + step int + out bytes.Buffer + err error + + clientNonce []byte + serverNonce []byte + saltedPass []byte + authMsg bytes.Buffer +} + +// NewClient returns a new SCRAM-* client with the provided hash algorithm. +// +// For SCRAM-SHA-256, for example, use: +// +// client := scram.NewClient(sha256.New, user, pass) +// +func NewClient(newHash func() hash.Hash, user, pass string) *Client { + c := &Client{ + newHash: newHash, + user: user, + pass: pass, + } + c.out.Grow(256) + c.authMsg.Grow(256) + return c +} + +// Out returns the data to be sent to the server in the current step. +func (c *Client) Out() []byte { + if c.out.Len() == 0 { + return nil + } + return c.out.Bytes() +} + +// Err returns the error that ocurred, or nil if there were no errors. +func (c *Client) Err() error { + return c.err +} + +// SetNonce sets the client nonce to the provided value. +// If not set, the nonce is generated automatically out of crypto/rand on the first step. +func (c *Client) SetNonce(nonce []byte) { + c.clientNonce = nonce +} + +var escaper = strings.NewReplacer("=", "=3D", ",", "=2C") + +// Step processes the incoming data from the server and makes the +// next round of data for the server available via Client.Out. +// Step returns false if there are no errors and more data is +// still expected. +func (c *Client) Step(in []byte) bool { + c.out.Reset() + if c.step > 2 || c.err != nil { + return false + } + c.step++ + switch c.step { + case 1: + c.err = c.step1(in) + case 2: + c.err = c.step2(in) + case 3: + c.err = c.step3(in) + } + return c.step > 2 || c.err != nil +} + +func (c *Client) step1(in []byte) error { + if len(c.clientNonce) == 0 { + const nonceLen = 16 + buf := make([]byte, nonceLen+b64.EncodedLen(nonceLen)) + if _, err := rand.Read(buf[:nonceLen]); err != nil { + return fmt.Errorf("cannot read random SCRAM-SHA-256 nonce from operating system: %v", err) + } + c.clientNonce = buf[nonceLen:] + b64.Encode(c.clientNonce, buf[:nonceLen]) + } + c.authMsg.WriteString("n=") + escaper.WriteString(&c.authMsg, c.user) + c.authMsg.WriteString(",r=") + c.authMsg.Write(c.clientNonce) + + c.out.WriteString("n,,") + c.out.Write(c.authMsg.Bytes()) + return nil +} + +var b64 = base64.StdEncoding + +func (c *Client) step2(in []byte) error { + c.authMsg.WriteByte(',') + c.authMsg.Write(in) + + fields := bytes.Split(in, []byte(",")) + if len(fields) != 3 { + return fmt.Errorf("expected 3 fields in first SCRAM-SHA-256 server message, got %d: %q", len(fields), in) + } + if !bytes.HasPrefix(fields[0], []byte("r=")) || len(fields[0]) < 2 { + return fmt.Errorf("server sent an invalid SCRAM-SHA-256 nonce: %q", fields[0]) + } + if !bytes.HasPrefix(fields[1], []byte("s=")) || len(fields[1]) < 6 { + return fmt.Errorf("server sent an invalid SCRAM-SHA-256 salt: %q", fields[1]) + } + if !bytes.HasPrefix(fields[2], []byte("i=")) || len(fields[2]) < 6 { + return fmt.Errorf("server sent an invalid SCRAM-SHA-256 iteration count: %q", fields[2]) + } + + c.serverNonce = fields[0][2:] + if !bytes.HasPrefix(c.serverNonce, c.clientNonce) { + return fmt.Errorf("server SCRAM-SHA-256 nonce is not prefixed by client nonce: got %q, want %q+\"...\"", c.serverNonce, c.clientNonce) + } + + salt := make([]byte, b64.DecodedLen(len(fields[1][2:]))) + n, err := b64.Decode(salt, fields[1][2:]) + if err != nil { + return fmt.Errorf("cannot decode SCRAM-SHA-256 salt sent by server: %q", fields[1]) + } + salt = salt[:n] + iterCount, err := strconv.Atoi(string(fields[2][2:])) + if err != nil { + return fmt.Errorf("server sent an invalid SCRAM-SHA-256 iteration count: %q", fields[2]) + } + c.saltPassword(salt, iterCount) + + c.authMsg.WriteString(",c=biws,r=") + c.authMsg.Write(c.serverNonce) + + c.out.WriteString("c=biws,r=") + c.out.Write(c.serverNonce) + c.out.WriteString(",p=") + c.out.Write(c.clientProof()) + return nil +} + +func (c *Client) step3(in []byte) error { + var isv, ise bool + var fields = bytes.Split(in, []byte(",")) + if len(fields) == 1 { + isv = bytes.HasPrefix(fields[0], []byte("v=")) + ise = bytes.HasPrefix(fields[0], []byte("e=")) + } + if ise { + return fmt.Errorf("SCRAM-SHA-256 authentication error: %s", fields[0][2:]) + } else if !isv { + return fmt.Errorf("unsupported SCRAM-SHA-256 final message from server: %q", in) + } + if !bytes.Equal(c.serverSignature(), fields[0][2:]) { + return fmt.Errorf("cannot authenticate SCRAM-SHA-256 server signature: %q", fields[0][2:]) + } + return nil +} + +func (c *Client) saltPassword(salt []byte, iterCount int) { + mac := hmac.New(c.newHash, []byte(c.pass)) + mac.Write(salt) + mac.Write([]byte{0, 0, 0, 1}) + ui := mac.Sum(nil) + hi := make([]byte, len(ui)) + copy(hi, ui) + for i := 1; i < iterCount; i++ { + mac.Reset() + mac.Write(ui) + mac.Sum(ui[:0]) + for j, b := range ui { + hi[j] ^= b + } + } + c.saltedPass = hi +} + +func (c *Client) clientProof() []byte { + mac := hmac.New(c.newHash, c.saltedPass) + mac.Write([]byte("Client Key")) + clientKey := mac.Sum(nil) + hash := c.newHash() + hash.Write(clientKey) + storedKey := hash.Sum(nil) + mac = hmac.New(c.newHash, storedKey) + mac.Write(c.authMsg.Bytes()) + clientProof := mac.Sum(nil) + for i, b := range clientKey { + clientProof[i] ^= b + } + clientProof64 := make([]byte, b64.EncodedLen(len(clientProof))) + b64.Encode(clientProof64, clientProof) + return clientProof64 +} + +func (c *Client) serverSignature() []byte { + mac := hmac.New(c.newHash, c.saltedPass) + mac.Write([]byte("Server Key")) + serverKey := mac.Sum(nil) + + mac = hmac.New(c.newHash, serverKey) + mac.Write(c.authMsg.Bytes()) + serverSignature := mac.Sum(nil) + + encoded := make([]byte, b64.EncodedLen(len(serverSignature))) + b64.Encode(encoded, serverSignature) + return encoded +}