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Diffstat (limited to 'src/crypto/tls/common.go')
| -rw-r--r-- | src/crypto/tls/common.go | 621 |
1 files changed, 621 insertions, 0 deletions
diff --git a/src/crypto/tls/common.go b/src/crypto/tls/common.go new file mode 100644 index 000000000..776b70c93 --- /dev/null +++ b/src/crypto/tls/common.go @@ -0,0 +1,621 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package tls + +import ( + "container/list" + "crypto" + "crypto/rand" + "crypto/x509" + "fmt" + "io" + "math/big" + "strings" + "sync" + "time" +) + +const ( + VersionSSL30 = 0x0300 + VersionTLS10 = 0x0301 + VersionTLS11 = 0x0302 + VersionTLS12 = 0x0303 +) + +const ( + maxPlaintext = 16384 // maximum plaintext payload length + maxCiphertext = 16384 + 2048 // maximum ciphertext payload length + recordHeaderLen = 5 // record header length + maxHandshake = 65536 // maximum handshake we support (protocol max is 16 MB) + + minVersion = VersionSSL30 + maxVersion = VersionTLS12 +) + +// TLS record types. +type recordType uint8 + +const ( + recordTypeChangeCipherSpec recordType = 20 + recordTypeAlert recordType = 21 + recordTypeHandshake recordType = 22 + recordTypeApplicationData recordType = 23 +) + +// TLS handshake message types. +const ( + typeClientHello uint8 = 1 + typeServerHello uint8 = 2 + typeNewSessionTicket uint8 = 4 + typeCertificate uint8 = 11 + typeServerKeyExchange uint8 = 12 + typeCertificateRequest uint8 = 13 + typeServerHelloDone uint8 = 14 + typeCertificateVerify uint8 = 15 + typeClientKeyExchange uint8 = 16 + typeFinished uint8 = 20 + typeCertificateStatus uint8 = 22 + typeNextProtocol uint8 = 67 // Not IANA assigned +) + +// TLS compression types. +const ( + compressionNone uint8 = 0 +) + +// TLS extension numbers +const ( + extensionServerName uint16 = 0 + extensionStatusRequest uint16 = 5 + extensionSupportedCurves uint16 = 10 + extensionSupportedPoints uint16 = 11 + extensionSignatureAlgorithms uint16 = 13 + extensionALPN uint16 = 16 + extensionSessionTicket uint16 = 35 + extensionNextProtoNeg uint16 = 13172 // not IANA assigned + extensionRenegotiationInfo uint16 = 0xff01 +) + +// TLS signaling cipher suite values +const ( + scsvRenegotiation uint16 = 0x00ff +) + +// CurveID is the type of a TLS identifier for an elliptic curve. See +// http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-8 +type CurveID uint16 + +const ( + CurveP256 CurveID = 23 + CurveP384 CurveID = 24 + CurveP521 CurveID = 25 +) + +// TLS Elliptic Curve Point Formats +// http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-9 +const ( + pointFormatUncompressed uint8 = 0 +) + +// TLS CertificateStatusType (RFC 3546) +const ( + statusTypeOCSP uint8 = 1 +) + +// Certificate types (for certificateRequestMsg) +const ( + certTypeRSASign = 1 // A certificate containing an RSA key + certTypeDSSSign = 2 // A certificate containing a DSA key + certTypeRSAFixedDH = 3 // A certificate containing a static DH key + certTypeDSSFixedDH = 4 // A certificate containing a static DH key + + // See RFC4492 sections 3 and 5.5. + certTypeECDSASign = 64 // A certificate containing an ECDSA-capable public key, signed with ECDSA. + certTypeRSAFixedECDH = 65 // A certificate containing an ECDH-capable public key, signed with RSA. + certTypeECDSAFixedECDH = 66 // A certificate containing an ECDH-capable public key, signed with ECDSA. + + // Rest of these are reserved by the TLS spec +) + +// Hash functions for TLS 1.2 (See RFC 5246, section A.4.1) +const ( + hashSHA1 uint8 = 2 + hashSHA256 uint8 = 4 +) + +// Signature algorithms for TLS 1.2 (See RFC 5246, section A.4.1) +const ( + signatureRSA uint8 = 1 + signatureECDSA uint8 = 3 +) + +// signatureAndHash mirrors the TLS 1.2, SignatureAndHashAlgorithm struct. See +// RFC 5246, section A.4.1. +type signatureAndHash struct { + hash, signature uint8 +} + +// supportedSKXSignatureAlgorithms contains the signature and hash algorithms +// that the code advertises as supported in a TLS 1.2 ClientHello. +var supportedSKXSignatureAlgorithms = []signatureAndHash{ + {hashSHA256, signatureRSA}, + {hashSHA256, signatureECDSA}, + {hashSHA1, signatureRSA}, + {hashSHA1, signatureECDSA}, +} + +// supportedClientCertSignatureAlgorithms contains the signature and hash +// algorithms that the code advertises as supported in a TLS 1.2 +// CertificateRequest. +var supportedClientCertSignatureAlgorithms = []signatureAndHash{ + {hashSHA256, signatureRSA}, + {hashSHA256, signatureECDSA}, +} + +// ConnectionState records basic TLS details about the connection. +type ConnectionState struct { + Version uint16 // TLS version used by the connection (e.g. VersionTLS12) + HandshakeComplete bool // TLS handshake is complete + DidResume bool // connection resumes a previous TLS connection + CipherSuite uint16 // cipher suite in use (TLS_RSA_WITH_RC4_128_SHA, ...) + NegotiatedProtocol string // negotiated next protocol (from Config.NextProtos) + NegotiatedProtocolIsMutual bool // negotiated protocol was advertised by server + ServerName string // server name requested by client, if any (server side only) + PeerCertificates []*x509.Certificate // certificate chain presented by remote peer + VerifiedChains [][]*x509.Certificate // verified chains built from PeerCertificates + + // TLSUnique contains the "tls-unique" channel binding value (see RFC + // 5929, section 3). For resumed sessions this value will be nil + // because resumption does not include enough context (see + // https://secure-resumption.com/#channelbindings). This will change in + // future versions of Go once the TLS master-secret fix has been + // standardized and implemented. + TLSUnique []byte +} + +// ClientAuthType declares the policy the server will follow for +// TLS Client Authentication. +type ClientAuthType int + +const ( + NoClientCert ClientAuthType = iota + RequestClientCert + RequireAnyClientCert + VerifyClientCertIfGiven + RequireAndVerifyClientCert +) + +// ClientSessionState contains the state needed by clients to resume TLS +// sessions. +type ClientSessionState struct { + sessionTicket []uint8 // Encrypted ticket used for session resumption with server + vers uint16 // SSL/TLS version negotiated for the session + cipherSuite uint16 // Ciphersuite negotiated for the session + masterSecret []byte // MasterSecret generated by client on a full handshake + serverCertificates []*x509.Certificate // Certificate chain presented by the server +} + +// ClientSessionCache is a cache of ClientSessionState objects that can be used +// by a client to resume a TLS session with a given server. ClientSessionCache +// implementations should expect to be called concurrently from different +// goroutines. +type ClientSessionCache interface { + // Get searches for a ClientSessionState associated with the given key. + // On return, ok is true if one was found. + Get(sessionKey string) (session *ClientSessionState, ok bool) + + // Put adds the ClientSessionState to the cache with the given key. + Put(sessionKey string, cs *ClientSessionState) +} + +// ClientHelloInfo contains information from a ClientHello message in order to +// guide certificate selection in the GetCertificate callback. +type ClientHelloInfo struct { + // CipherSuites lists the CipherSuites supported by the client (e.g. + // TLS_RSA_WITH_RC4_128_SHA). + CipherSuites []uint16 + + // ServerName indicates the name of the server requested by the client + // in order to support virtual hosting. ServerName is only set if the + // client is using SNI (see + // http://tools.ietf.org/html/rfc4366#section-3.1). + ServerName string + + // SupportedCurves lists the elliptic curves supported by the client. + // SupportedCurves is set only if the Supported Elliptic Curves + // Extension is being used (see + // http://tools.ietf.org/html/rfc4492#section-5.1.1). + SupportedCurves []CurveID + + // SupportedPoints lists the point formats supported by the client. + // SupportedPoints is set only if the Supported Point Formats Extension + // is being used (see + // http://tools.ietf.org/html/rfc4492#section-5.1.2). + SupportedPoints []uint8 +} + +// A Config structure is used to configure a TLS client or server. +// After one has been passed to a TLS function it must not be +// modified. A Config may be reused; the tls package will also not +// modify it. +type Config struct { + // Rand provides the source of entropy for nonces and RSA blinding. + // If Rand is nil, TLS uses the cryptographic random reader in package + // crypto/rand. + // The Reader must be safe for use by multiple goroutines. + Rand io.Reader + + // Time returns the current time as the number of seconds since the epoch. + // If Time is nil, TLS uses time.Now. + Time func() time.Time + + // Certificates contains one or more certificate chains + // to present to the other side of the connection. + // Server configurations must include at least one certificate. + Certificates []Certificate + + // NameToCertificate maps from a certificate name to an element of + // Certificates. Note that a certificate name can be of the form + // '*.example.com' and so doesn't have to be a domain name as such. + // See Config.BuildNameToCertificate + // The nil value causes the first element of Certificates to be used + // for all connections. + NameToCertificate map[string]*Certificate + + // GetCertificate returns a Certificate based on the given + // ClientHelloInfo. If GetCertificate is nil or returns nil, then the + // certificate is retrieved from NameToCertificate. If + // NameToCertificate is nil, the first element of Certificates will be + // used. + GetCertificate func(clientHello *ClientHelloInfo) (*Certificate, error) + + // RootCAs defines the set of root certificate authorities + // that clients use when verifying server certificates. + // If RootCAs is nil, TLS uses the host's root CA set. + RootCAs *x509.CertPool + + // NextProtos is a list of supported, application level protocols. + NextProtos []string + + // ServerName is used to verify the hostname on the returned + // certificates unless InsecureSkipVerify is given. It is also included + // in the client's handshake to support virtual hosting. + ServerName string + + // ClientAuth determines the server's policy for + // TLS Client Authentication. The default is NoClientCert. + ClientAuth ClientAuthType + + // ClientCAs defines the set of root certificate authorities + // that servers use if required to verify a client certificate + // by the policy in ClientAuth. + ClientCAs *x509.CertPool + + // InsecureSkipVerify controls whether a client verifies the + // server's certificate chain and host name. + // If InsecureSkipVerify is true, TLS accepts any certificate + // presented by the server and any host name in that certificate. + // In this mode, TLS is susceptible to man-in-the-middle attacks. + // This should be used only for testing. + InsecureSkipVerify bool + + // CipherSuites is a list of supported cipher suites. If CipherSuites + // is nil, TLS uses a list of suites supported by the implementation. + CipherSuites []uint16 + + // PreferServerCipherSuites controls whether the server selects the + // client's most preferred ciphersuite, or the server's most preferred + // ciphersuite. If true then the server's preference, as expressed in + // the order of elements in CipherSuites, is used. + PreferServerCipherSuites bool + + // SessionTicketsDisabled may be set to true to disable session ticket + // (resumption) support. + SessionTicketsDisabled bool + + // SessionTicketKey is used by TLS servers to provide session + // resumption. See RFC 5077. If zero, it will be filled with + // random data before the first server handshake. + // + // If multiple servers are terminating connections for the same host + // they should all have the same SessionTicketKey. If the + // SessionTicketKey leaks, previously recorded and future TLS + // connections using that key are compromised. + SessionTicketKey [32]byte + + // SessionCache is a cache of ClientSessionState entries for TLS session + // resumption. + ClientSessionCache ClientSessionCache + + // MinVersion contains the minimum SSL/TLS version that is acceptable. + // If zero, then SSLv3 is taken as the minimum. + MinVersion uint16 + + // MaxVersion contains the maximum SSL/TLS version that is acceptable. + // If zero, then the maximum version supported by this package is used, + // which is currently TLS 1.2. + MaxVersion uint16 + + // CurvePreferences contains the elliptic curves that will be used in + // an ECDHE handshake, in preference order. If empty, the default will + // be used. + CurvePreferences []CurveID + + serverInitOnce sync.Once // guards calling (*Config).serverInit +} + +func (c *Config) serverInit() { + if c.SessionTicketsDisabled { + return + } + + // If the key has already been set then we have nothing to do. + for _, b := range c.SessionTicketKey { + if b != 0 { + return + } + } + + if _, err := io.ReadFull(c.rand(), c.SessionTicketKey[:]); err != nil { + c.SessionTicketsDisabled = true + } +} + +func (c *Config) rand() io.Reader { + r := c.Rand + if r == nil { + return rand.Reader + } + return r +} + +func (c *Config) time() time.Time { + t := c.Time + if t == nil { + t = time.Now + } + return t() +} + +func (c *Config) cipherSuites() []uint16 { + s := c.CipherSuites + if s == nil { + s = defaultCipherSuites() + } + return s +} + +func (c *Config) minVersion() uint16 { + if c == nil || c.MinVersion == 0 { + return minVersion + } + return c.MinVersion +} + +func (c *Config) maxVersion() uint16 { + if c == nil || c.MaxVersion == 0 { + return maxVersion + } + return c.MaxVersion +} + +var defaultCurvePreferences = []CurveID{CurveP256, CurveP384, CurveP521} + +func (c *Config) curvePreferences() []CurveID { + if c == nil || len(c.CurvePreferences) == 0 { + return defaultCurvePreferences + } + return c.CurvePreferences +} + +// mutualVersion returns the protocol version to use given the advertised +// version of the peer. +func (c *Config) mutualVersion(vers uint16) (uint16, bool) { + minVersion := c.minVersion() + maxVersion := c.maxVersion() + + if vers < minVersion { + return 0, false + } + if vers > maxVersion { + vers = maxVersion + } + return vers, true +} + +// getCertificate returns the best certificate for the given ClientHelloInfo, +// defaulting to the first element of c.Certificates. +func (c *Config) getCertificate(clientHello *ClientHelloInfo) (*Certificate, error) { + if c.GetCertificate != nil { + cert, err := c.GetCertificate(clientHello) + if cert != nil || err != nil { + return cert, err + } + } + + if len(c.Certificates) == 1 || c.NameToCertificate == nil { + // There's only one choice, so no point doing any work. + return &c.Certificates[0], nil + } + + name := strings.ToLower(clientHello.ServerName) + for len(name) > 0 && name[len(name)-1] == '.' { + name = name[:len(name)-1] + } + + if cert, ok := c.NameToCertificate[name]; ok { + return cert, nil + } + + // try replacing labels in the name with wildcards until we get a + // match. + labels := strings.Split(name, ".") + for i := range labels { + labels[i] = "*" + candidate := strings.Join(labels, ".") + if cert, ok := c.NameToCertificate[candidate]; ok { + return cert, nil + } + } + + // If nothing matches, return the first certificate. + return &c.Certificates[0], nil +} + +// BuildNameToCertificate parses c.Certificates and builds c.NameToCertificate +// from the CommonName and SubjectAlternateName fields of each of the leaf +// certificates. +func (c *Config) BuildNameToCertificate() { + c.NameToCertificate = make(map[string]*Certificate) + for i := range c.Certificates { + cert := &c.Certificates[i] + x509Cert, err := x509.ParseCertificate(cert.Certificate[0]) + if err != nil { + continue + } + if len(x509Cert.Subject.CommonName) > 0 { + c.NameToCertificate[x509Cert.Subject.CommonName] = cert + } + for _, san := range x509Cert.DNSNames { + c.NameToCertificate[san] = cert + } + } +} + +// A Certificate is a chain of one or more certificates, leaf first. +type Certificate struct { + Certificate [][]byte + // PrivateKey contains the private key corresponding to the public key + // in Leaf. For a server, this must be a *rsa.PrivateKey or + // *ecdsa.PrivateKey. For a client doing client authentication, this + // can be any type that implements crypto.Signer (which includes RSA + // and ECDSA private keys). + PrivateKey crypto.PrivateKey + // OCSPStaple contains an optional OCSP response which will be served + // to clients that request it. + OCSPStaple []byte + // Leaf is the parsed form of the leaf certificate, which may be + // initialized using x509.ParseCertificate to reduce per-handshake + // processing for TLS clients doing client authentication. If nil, the + // leaf certificate will be parsed as needed. + Leaf *x509.Certificate +} + +// A TLS record. +type record struct { + contentType recordType + major, minor uint8 + payload []byte +} + +type handshakeMessage interface { + marshal() []byte + unmarshal([]byte) bool +} + +// lruSessionCache is a ClientSessionCache implementation that uses an LRU +// caching strategy. +type lruSessionCache struct { + sync.Mutex + + m map[string]*list.Element + q *list.List + capacity int +} + +type lruSessionCacheEntry struct { + sessionKey string + state *ClientSessionState +} + +// NewLRUClientSessionCache returns a ClientSessionCache with the given +// capacity that uses an LRU strategy. If capacity is < 1, a default capacity +// is used instead. +func NewLRUClientSessionCache(capacity int) ClientSessionCache { + const defaultSessionCacheCapacity = 64 + + if capacity < 1 { + capacity = defaultSessionCacheCapacity + } + return &lruSessionCache{ + m: make(map[string]*list.Element), + q: list.New(), + capacity: capacity, + } +} + +// Put adds the provided (sessionKey, cs) pair to the cache. +func (c *lruSessionCache) Put(sessionKey string, cs *ClientSessionState) { + c.Lock() + defer c.Unlock() + + if elem, ok := c.m[sessionKey]; ok { + entry := elem.Value.(*lruSessionCacheEntry) + entry.state = cs + c.q.MoveToFront(elem) + return + } + + if c.q.Len() < c.capacity { + entry := &lruSessionCacheEntry{sessionKey, cs} + c.m[sessionKey] = c.q.PushFront(entry) + return + } + + elem := c.q.Back() + entry := elem.Value.(*lruSessionCacheEntry) + delete(c.m, entry.sessionKey) + entry.sessionKey = sessionKey + entry.state = cs + c.q.MoveToFront(elem) + c.m[sessionKey] = elem +} + +// Get returns the ClientSessionState value associated with a given key. It +// returns (nil, false) if no value is found. +func (c *lruSessionCache) Get(sessionKey string) (*ClientSessionState, bool) { + c.Lock() + defer c.Unlock() + + if elem, ok := c.m[sessionKey]; ok { + c.q.MoveToFront(elem) + return elem.Value.(*lruSessionCacheEntry).state, true + } + return nil, false +} + +// TODO(jsing): Make these available to both crypto/x509 and crypto/tls. +type dsaSignature struct { + R, S *big.Int +} + +type ecdsaSignature dsaSignature + +var emptyConfig Config + +func defaultConfig() *Config { + return &emptyConfig +} + +var ( + once sync.Once + varDefaultCipherSuites []uint16 +) + +func defaultCipherSuites() []uint16 { + once.Do(initDefaultCipherSuites) + return varDefaultCipherSuites +} + +func initDefaultCipherSuites() { + varDefaultCipherSuites = make([]uint16, len(cipherSuites)) + for i, suite := range cipherSuites { + varDefaultCipherSuites[i] = suite.id + } +} + +func unexpectedMessageError(wanted, got interface{}) error { + return fmt.Errorf("tls: received unexpected handshake message of type %T when waiting for %T", got, wanted) +} |