/
auth.go
481 lines (437 loc) · 12.5 KB
/
auth.go
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/*************************************************************************
* Copyright 2017 Gravwell, Inc. All rights reserved.
* Contact: <legal@gravwell.io>
*
* This software may be modified and distributed under the terms of the
* BSD 2-clause license. See the LICENSE file for details.
**************************************************************************/
package ingest
import (
"bytes"
"crypto/md5"
"crypto/sha256"
"crypto/sha512"
"encoding/binary"
"encoding/json"
"errors"
"io"
"math/rand"
"github.com/gravwell/gravwell/v3/ingest/entry"
)
const (
// The number of times to hash the shared secret
HASH_ITERATIONS uint16 = 16
// Auth protocol version number
VERSION uint16 = 0x8
// Authenticated, but not ready for ingest
STATE_AUTHENTICATED uint32 = 0xBEEF42
// Not authenticated
STATE_NOT_AUTHENTICATED uint32 = 0xFEED51
// Authenticated and ready for ingest
STATE_HOT uint32 = 0xCAFE54
// Minimum auth version supporting tenants
MinTenantAuthVersion uint16 = 0x7
MaxTenantNameLength uint16 = 512 //maximum length of a tenant name in bytes
SystemTenant string = `` // blank string, basically the root/system/infrastructure user
// Max length for a state response message
maxStateResponseLen uint16 = 4096
// Maximum size of a message requesting tags from ingester
maxTagRequestLen uint32 = 32 * 1024 * 1024 //32megs for a request, which is crazy huge
// Maximum size of a message mapping tag names to tag numbers
maxTagResponseLen uint32 = 64 * 1024 * 1024 //64megs for a response, which is crazy huge
minPrngLife = 1024 //how many iterations on the PRNG before we demand a new cryptographically secure seed
prngVariance = 1024 //how much randomness in the PRNG life we allow
)
var (
ErrInvalidStateResponseLen = errors.New("Invalid state response length")
ErrInvalidTagRequestLen = errors.New("Invalid tag request length")
ErrInvalidTagResponseLen = errors.New("Invalid tag response length")
ErrFailedAuthHashGen = errors.New("Failed to generate authentication hash")
ErrFailedAuth = errors.New("Failed authentication, bad secret")
ErrFailedTagNegotiation = errors.New("Failed to negotiate tags")
ErrShortRead = errors.New("Failed to read complete buffer")
ErrShortWrite = errors.New("Failed to write complete buffer")
ErrInvalidAuthVersion = errors.New("auth version is invalid")
ErrInvalidTenantName = errors.New("auth tenant name is invalid")
ErrNilChallengeResponse = errors.New("Got a nil challenge response")
ErrTenantAuthUnsupported = errors.New("authentication endpoint does not support tenants")
prng *rand.Rand
prngCounter int
)
var tenantAuthHeader = [32]byte{
0x67, 0x72, 0x61, 0x76, 0x77, 0x65, 0x6c, 0x6c,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x74, 0x65, 0x6e, 0x61, 0x6e, 0x74, 0x30, 0x31}
// AuthHash represents a hashed shared secret.
type AuthHash [16]byte
// Challenge request, used to validate remote clients.
// The server generates RandChallenge, a random number which is hashed
// with the pre-hashed shared secret, then run through Iterate iterations
// of md5 and sha256 to create the response.
type Challenge struct {
// Number of times to iterate the hash
Iterate uint16
// The random number to be hashed with the secret
RandChallenge [32]byte
// Authentication version number
Version uint16
}
// ChallengeResponse is the resulting hash sent back as part of
// the challenge/response process.
type ChallengeResponse struct {
Response [32]byte
Version uint16
Tenant string
}
// TagRequest is used to request tags for the ingester
type TagRequest struct {
Count uint32
Tags []string
}
// TagResponse represents the Tag Name to Tag Number mapping supported by the ingest server
type TagResponse struct {
Count uint32
Tags map[string]entry.EntryTag
}
// StateResponse
type StateResponse struct {
ID uint32
Info string
}
func init() {
var err error
prng, err = NewRNG()
if err != nil {
panic(err)
}
prngCounter = rand.Intn(prngVariance) + minPrngLife
}
// GenAuthHash takes a key and generates a hash using the "password" token
// we iterate over the value, hashing with MD5 and SHA256. We choose these
// two algorithms because they aren't too heavy, but the alternating makes it
// very difficult to optimize in an FPGA or ASIC.
func GenAuthHash(password string) (AuthHash, error) {
var runningHash []byte
var auth AuthHash
// hash first with SHA512 to ensure we don't accidentally shrink our keyspace
h512 := sha512.New()
io.WriteString(h512, password)
runningHash = h512.Sum(nil)
for i := uint16(0); i < HASH_ITERATIONS; i++ {
md := md5.New()
size, err := md.Write(runningHash)
if err != nil {
return auth, err
}
if size != len(runningHash) {
return auth, errors.New("Failed to write to MD5")
}
runningHash = md.Sum(nil)
sh := sha256.New()
size, err = sh.Write(runningHash)
if err != nil {
return auth, err
}
if size != len(runningHash) {
return auth, errors.New("Failed to write to MD5")
}
runningHash = sh.Sum(nil)
}
for i := 0; i < len(auth); i++ {
auth[i] = runningHash[i]
}
return auth, nil
}
// VerifyResponse takes a hash and challenge and computes a completed response.
// If the computed response does not match an error is returned. If the response
// matches, nil is returned
func VerifyResponse(auth AuthHash, chal Challenge, resp ChallengeResponse) error {
vResp, err := GenerateResponse(auth, chal)
if err != nil {
return err
}
for i := 0; i < len(vResp.Response); i++ {
if vResp.Response[i] != resp.Response[i] {
return errors.New("Verification Failed")
}
}
return nil
}
func checkAndReseedPRNG() {
prngCounter -= 1
if prngCounter <= 0 {
if seed, err := SecureSeed(); err == nil {
prng.Seed(seed)
}
prngCounter = rand.Intn(prngVariance) + minPrngLife
}
}
// NewChallenge generates a random hash string and a random iteration count
func NewChallenge(auth AuthHash) (Challenge, error) {
var chal [32]byte
checkAndReseedPRNG()
iter := uint16(10000 + prng.Intn(10000))
for i := 0; i < len(chal); i++ {
chal[i] = byte(prng.Intn(0xff))
}
return Challenge{
Iterate: iter,
RandChallenge: chal,
Version: VERSION,
}, nil
}
// GenerateResponse creates a ChallengeResponse based on the Challenge and AuthHash
func GenerateResponse(auth AuthHash, ch Challenge) (resp *ChallengeResponse, err error) {
resp = &ChallengeResponse{
Version: ch.Version,
}
//hash first with SHA512
runningHash := make([]byte, 32)
authSlice := make([]byte, len(auth))
for i := 0; i < 32; i++ {
runningHash[i] = ch.RandChallenge[i]
}
for i := 0; i < len(auth); i++ {
authSlice[i] = auth[i]
}
sha := sha512.New()
if _, err = sha.Write(runningHash); err != nil {
return
} else if _, err = sha.Write(authSlice); err != nil {
return
}
runningHash = sha.Sum(nil)
for i := uint16(0); i < ch.Iterate; i++ {
md := md5.New()
if _, err = md.Write(runningHash); err != nil {
return
}
runningHash = md.Sum(nil)
sha := sha256.New()
if _, err = sha.Write(runningHash); err != nil {
return
}
runningHash = sha.Sum(nil)
}
//NOTE: The last hash HAS to be SHA256 because we expect
//a 32 byte result
for i := 0; i < len(resp.Response); i++ {
resp.Response[i] = runningHash[i]
}
return
}
// Decode the ChallengeResponse from the reader
func (cr *ChallengeResponse) Read(r io.Reader) error {
var buff [32]byte
if n, err := r.Read(buff[:]); err != nil {
return err
} else if n != len(cr.Response) {
return ErrShortRead
}
if buff != tenantAuthHeader {
cr.Response = buff
return nil
}
if n, err := r.Read(buff[:]); err != nil {
return err
} else if n != len(cr.Response) {
return ErrShortRead
}
cr.Response = buff
return cr.readTenantResponse(r)
}
func (cr *ChallengeResponse) readTenantResponse(r io.Reader) error {
//read the version and length
var version uint16
var length uint16
if err := binary.Read(r, binary.LittleEndian, &version); err != nil {
return err
} else if err = binary.Read(r, binary.LittleEndian, &length); err != nil {
return err
}
if version < MinTenantAuthVersion {
return ErrInvalidAuthVersion
} else if length > MaxTenantNameLength {
return ErrInvalidTenantName
}
namebuff := make([]byte, length)
if n, err := r.Read(namebuff); err != nil {
return err
} else if n != int(length) {
return ErrShortRead
}
cr.Version = version
cr.Tenant = string(namebuff)
return nil
}
// Write the challenge response to the writer
func (cr *ChallengeResponse) Write(w io.Writer) error {
if cr.Version < MinTenantAuthVersion || len(cr.Tenant) == 0 {
return cr.writeNonTenantAuth(w)
}
return cr.writeTenantAuth(w)
}
func (cr *ChallengeResponse) writeNonTenantAuth(w io.Writer) error {
if n, err := w.Write(cr.Response[:]); err != nil {
return err
} else if n != len(cr.Response) {
return ErrShortWrite
}
return nil
}
func (cr *ChallengeResponse) writeTenantAuth(w io.Writer) error {
//double check what we have
if len(cr.Tenant) > int(MaxTenantNameLength) {
return ErrInvalidTenantName
} else if cr.Version < MinTenantAuthVersion {
return ErrInvalidAuthVersion
}
// write header
if n, err := w.Write(tenantAuthHeader[:]); err != nil {
return err
} else if n != len(tenantAuthHeader) {
return ErrShortWrite
}
// then response
if n, err := w.Write(cr.Response[:]); err != nil {
return err
} else if n != len(cr.Response) {
return ErrShortWrite
}
// then version and tenant length and tenant string
if err := binary.Write(w, binary.LittleEndian, cr.Version); err != nil {
return err
} else if err = binary.Write(w, binary.LittleEndian, uint16(len(cr.Tenant))); err != nil {
return err
}
// then tenant name
return writeString(w, cr.Tenant)
}
func writeString(w io.Writer, v string) error {
l := len(v)
if n, err := w.Write([]byte(v)); err != nil {
return err
} else if l != n {
return ErrShortWrite
}
return nil
}
// Read the challenge from reader
func (c *Challenge) Read(r io.Reader) error {
return binary.Read(r, binary.LittleEndian, c)
}
// Write out the challenge to w
func (c *Challenge) Write(w io.Writer) error {
return binary.Write(w, binary.LittleEndian, c)
}
// Read reads a state response from the reader
func (sr *StateResponse) Read(r io.Reader) error {
var l uint16
if err := binary.Read(r, binary.LittleEndian, &l); err != nil {
return err
}
if l > maxStateResponseLen {
return ErrInvalidStateResponseLen
}
bb := make([]byte, int(l))
if _, err := io.ReadFull(r, bb); err != nil {
return err
}
if err := json.Unmarshal(bb, sr); err != nil {
return err
}
return nil
}
// Write the StateResponse
func (sr *StateResponse) Write(w io.Writer) error {
bb, err := json.Marshal(sr)
if err != nil {
return err
}
if int(maxStateResponseLen) < len(bb) {
return ErrInvalidStateResponseLen
}
l := uint16(len(bb))
if err := binary.Write(w, binary.LittleEndian, l); err != nil {
return err
}
n, err := io.Copy(w, bytes.NewBuffer(bb))
if err != nil {
return err
}
if uint16(n) != l {
return errors.New("Failed to write entire state response")
}
return nil
}
// Read a TagRequest structure
func (tr *TagRequest) Read(r io.Reader) error {
var l uint32
if err := binary.Read(r, binary.LittleEndian, &l); err != nil {
return err
}
if l > maxTagRequestLen {
return ErrInvalidTagRequestLen
}
bb := make([]byte, int(l))
if _, err := io.ReadFull(r, bb); err != nil {
return err
}
if err := json.Unmarshal(bb, tr); err != nil {
return err
}
return nil
}
// Write a TagRequest
func (tr *TagRequest) Write(w io.Writer) error {
bs, err := json.Marshal(tr)
if err != nil {
return err
}
if uint32(len(bs)) > maxTagRequestLen {
return ErrInvalidTagRequestLen
}
if err := binary.Write(w, binary.LittleEndian, uint32(len(bs))); err != nil {
return err
}
if _, err := io.Copy(w, bytes.NewBuffer(bs)); err != nil {
return err
}
return nil
}
// Read a TagResponse
func (tr *TagResponse) Read(r io.Reader) error {
var l uint32
if err := binary.Read(r, binary.LittleEndian, &l); err != nil {
return err
}
if l > maxTagRequestLen {
return ErrInvalidTagResponseLen
}
bb := make([]byte, int(l))
if _, err := io.ReadFull(r, bb); err != nil {
return err
}
if err := json.Unmarshal(bb, tr); err != nil {
return err
}
return nil
}
// Write a TagResponse
func (tr *TagResponse) Write(w io.Writer) error {
bs, err := json.Marshal(tr)
if err != nil {
return err
}
if uint32(len(bs)) > maxTagRequestLen {
return ErrInvalidTagResponseLen
}
if err := binary.Write(w, binary.LittleEndian, uint32(len(bs))); err != nil {
return err
}
if _, err := io.Copy(w, bytes.NewBuffer(bs)); err != nil {
return err
}
return nil
}