diff options
Diffstat (limited to 'libgo/go/crypto/tls/common.go')
| -rw-r--r-- | libgo/go/crypto/tls/common.go | 324 |
1 files changed, 223 insertions, 101 deletions
diff --git a/libgo/go/crypto/tls/common.go b/libgo/go/crypto/tls/common.go index c3de0b3..e8d0091 100644 --- a/libgo/go/crypto/tls/common.go +++ b/libgo/go/crypto/tls/common.go @@ -19,7 +19,6 @@ import ( "fmt" "internal/cpu" "io" - "math/big" "net" "strings" "sync" @@ -208,30 +207,78 @@ const ( downgradeCanaryTLS11 = "DOWNGRD\x00" ) +// testingOnlyForceDowngradeCanary is set in tests to force the server side to +// include downgrade canaries even if it's using its highers supported version. +var testingOnlyForceDowngradeCanary bool + // 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_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, ...) - NegotiatedProtocol string // negotiated next protocol (not guaranteed to be from Config.NextProtos) - NegotiatedProtocolIsMutual bool // negotiated protocol was advertised by server (client side only) - 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 - SignedCertificateTimestamps [][]byte // SCTs from the peer, if any - OCSPResponse []byte // stapled OCSP response from peer, if any + // Version is the TLS version used by the connection (e.g. VersionTLS12). + Version uint16 - // ekm is a closure exposed via ExportKeyingMaterial. - ekm func(label string, context []byte, length int) ([]byte, error) + // HandshakeComplete is true if the handshake has concluded. + HandshakeComplete bool + + // DidResume is true if this connection was successfully resumed from a + // previous session with a session ticket or similar mechanism. + DidResume bool + + // CipherSuite is the cipher suite negotiated for the connection (e.g. + // TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_AES_128_GCM_SHA256). + CipherSuite uint16 + + // NegotiatedProtocol is the application protocol negotiated with ALPN. + // + // Note that on the client side, this is currently not guaranteed to be from + // Config.NextProtos. + NegotiatedProtocol string + + // NegotiatedProtocolIsMutual used to indicate a mutual NPN negotiation. + // + // Deprecated: this value is always true. + NegotiatedProtocolIsMutual bool + + // ServerName is the value of the Server Name Indication extension sent by + // the client. It's available both on the server and on the client side. + ServerName string + + // PeerCertificates are the parsed certificates sent by the peer, in the + // order in which they were sent. The first element is the leaf certificate + // that the connection is verified against. + // + // On the client side, it can't be empty. On the server side, it can be + // empty if Config.ClientAuth is not RequireAnyClientCert or + // RequireAndVerifyClientCert. + PeerCertificates []*x509.Certificate + + // VerifiedChains is a list of one or more chains where the first element is + // PeerCertificates[0] and the last element is from Config.RootCAs (on the + // client side) or Config.ClientCAs (on the server side). + // + // On the client side, it's set if Config.InsecureSkipVerify is false. On + // the server side, it's set if Config.ClientAuth is VerifyClientCertIfGiven + // (and the peer provided a certificate) or RequireAndVerifyClientCert. + VerifiedChains [][]*x509.Certificate - // 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://mitls.org/pages/attacks/3SHAKE#channelbindings). This will - // change in future versions of Go once the TLS master-secret fix has - // been standardized and implemented. It is not defined in TLS 1.3. + // SignedCertificateTimestamps is a list of SCTs provided by the peer + // through the TLS handshake for the leaf certificate, if any. + SignedCertificateTimestamps [][]byte + + // OCSPResponse is a stapled Online Certificate Status Protocol (OCSP) + // response provided by the peer for the leaf certificate, if any. + OCSPResponse []byte + + // TLSUnique contains the "tls-unique" channel binding value (see RFC 5929, + // Section 3). This value will be nil for TLS 1.3 connections and for all + // resumed connections. + // + // Deprecated: there are conditions in which this value might not be unique + // to a connection. See the Security Considerations sections of RFC 5705 and + // RFC 7627, and https://mitls.org/pages/attacks/3SHAKE#channelbindings. TLSUnique []byte + + // ekm is a closure exposed via ExportKeyingMaterial. + ekm func(label string, context []byte, length int) ([]byte, error) } // ExportKeyingMaterial returns length bytes of exported key material in a new @@ -275,6 +322,8 @@ type ClientSessionState struct { serverCertificates []*x509.Certificate // Certificate chain presented by the server verifiedChains [][]*x509.Certificate // Certificate chains we built for verification receivedAt time.Time // When the session ticket was received from the server + ocspResponse []byte // Stapled OCSP response presented by the server + scts [][]byte // SCTs presented by the server // TLS 1.3 fields. nonce []byte // Ticket nonce sent by the server, to derive PSK @@ -300,6 +349,8 @@ type ClientSessionCache interface { Put(sessionKey string, cs *ClientSessionState) } +//go:generate stringer -type=SignatureScheme,CurveID,ClientAuthType -output=common_string.go + // SignatureScheme identifies a signature algorithm supported by TLS. See // RFC 8446, Section 4.2.3. type SignatureScheme uint16 @@ -496,15 +547,10 @@ type Config struct { // If GetConfigForClient is nil, the Config passed to Server() will be // used for all connections. // - // Uniquely for the fields in the returned Config, session ticket keys - // will be duplicated from the original Config if not set. - // Specifically, if SetSessionTicketKeys was called on the original - // config but not on the returned config then the ticket keys from the - // original config will be copied into the new config before use. - // Otherwise, if SessionTicketKey was set in the original config but - // not in the returned config then it will be copied into the returned - // config before use. If neither of those cases applies then the key - // material from the returned config will be used for session tickets. + // If SessionTicketKey was explicitly set on the returned Config, or if + // SetSessionTicketKeys was called on the returned Config, those keys will + // be used. Otherwise, the original Config keys will be used (and possibly + // rotated if they are automatically managed). GetConfigForClient func(*ClientHelloInfo) (*Config, error) // VerifyPeerCertificate, if not nil, is called after normal @@ -520,6 +566,16 @@ type Config struct { // be considered but the verifiedChains argument will always be nil. VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error + // VerifyConnection, if not nil, is called after normal certificate + // verification and after VerifyPeerCertificate by either a TLS client + // or server. If it returns a non-nil error, the handshake is aborted + // and that error results. + // + // If normal verification fails then the handshake will abort before + // considering this callback. This callback will run for all connections + // regardless of InsecureSkipVerify or ClientAuth settings. + VerifyConnection func(ConnectionState) 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. @@ -544,12 +600,12 @@ type Config struct { // 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 controls whether a client verifies the server's + // certificate chain and host name. If InsecureSkipVerify is true, crypto/tls + // accepts any certificate presented by the server and any host name in that + // certificate. In this mode, TLS is susceptible to machine-in-the-middle + // attacks unless custom verification is used. This should be used only for + // testing or in combination with VerifyConnection or VerifyPeerCertificate. InsecureSkipVerify bool // CipherSuites is a list of supported cipher suites for TLS versions up to @@ -574,10 +630,10 @@ type Config struct { // See RFC 5077 and the PSK mode of RFC 8446. 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 might be compromised. + // Deprecated: if this field is left at zero, session ticket keys will be + // automatically rotated every day and dropped after seven days. For + // customizing the rotation schedule or synchronizing servers that are + // terminating connections for the same host, use SetSessionTicketKeys. SessionTicketKey [32]byte // ClientSessionCache is a cache of ClientSessionState entries for TLS @@ -617,20 +673,32 @@ type Config struct { // used for debugging. KeyLogWriter io.Writer - serverInitOnce sync.Once // guards calling (*Config).serverInit - - // mutex protects sessionTicketKeys. + // mutex protects sessionTicketKeys and autoSessionTicketKeys. mutex sync.RWMutex - // sessionTicketKeys contains zero or more ticket keys. If the length - // is zero, SessionTicketsDisabled must be true. The first key is used - // for new tickets and any subsequent keys can be used to decrypt old - // tickets. + // sessionTicketKeys contains zero or more ticket keys. If set, it means the + // the keys were set with SessionTicketKey or SetSessionTicketKeys. The + // first key is used for new tickets and any subsequent keys can be used to + // decrypt old tickets. The slice contents are not protected by the mutex + // and are immutable. sessionTicketKeys []ticketKey + // autoSessionTicketKeys is like sessionTicketKeys but is owned by the + // auto-rotation logic. See Config.ticketKeys. + autoSessionTicketKeys []ticketKey } -// ticketKeyNameLen is the number of bytes of identifier that is prepended to -// an encrypted session ticket in order to identify the key used to encrypt it. -const ticketKeyNameLen = 16 +const ( + // ticketKeyNameLen is the number of bytes of identifier that is prepended to + // an encrypted session ticket in order to identify the key used to encrypt it. + ticketKeyNameLen = 16 + + // ticketKeyLifetime is how long a ticket key remains valid and can be used to + // resume a client connection. + ticketKeyLifetime = 7 * 24 * time.Hour // 7 days + + // ticketKeyRotation is how often the server should rotate the session ticket key + // that is used for new tickets. + ticketKeyRotation = 24 * time.Hour +) // ticketKey is the internal representation of a session ticket key. type ticketKey struct { @@ -639,16 +707,19 @@ type ticketKey struct { keyName [ticketKeyNameLen]byte aesKey [16]byte hmacKey [16]byte + // created is the time at which this ticket key was created. See Config.ticketKeys. + created time.Time } // ticketKeyFromBytes converts from the external representation of a session // ticket key to a ticketKey. Externally, session ticket keys are 32 random // bytes and this function expands that into sufficient name and key material. -func ticketKeyFromBytes(b [32]byte) (key ticketKey) { +func (c *Config) ticketKeyFromBytes(b [32]byte) (key ticketKey) { hashed := sha512.Sum512(b[:]) copy(key.keyName[:], hashed[:ticketKeyNameLen]) copy(key.aesKey[:], hashed[ticketKeyNameLen:ticketKeyNameLen+16]) copy(key.hmacKey[:], hashed[ticketKeyNameLen+16:ticketKeyNameLen+32]) + key.created = c.time() return key } @@ -659,15 +730,8 @@ const maxSessionTicketLifetime = 7 * 24 * time.Hour // Clone returns a shallow clone of c. It is safe to clone a Config that is // being used concurrently by a TLS client or server. func (c *Config) Clone() *Config { - // Running serverInit ensures that it's safe to read - // SessionTicketsDisabled. - c.serverInitOnce.Do(func() { c.serverInit(nil) }) - - var sessionTicketKeys []ticketKey c.mutex.RLock() - sessionTicketKeys = c.sessionTicketKeys - c.mutex.RUnlock() - + defer c.mutex.RUnlock() return &Config{ Rand: c.Rand, Time: c.Time, @@ -677,6 +741,7 @@ func (c *Config) Clone() *Config { GetClientCertificate: c.GetClientCertificate, GetConfigForClient: c.GetConfigForClient, VerifyPeerCertificate: c.VerifyPeerCertificate, + VerifyConnection: c.VerifyConnection, RootCAs: c.RootCAs, NextProtos: c.NextProtos, ServerName: c.ServerName, @@ -694,58 +759,122 @@ func (c *Config) Clone() *Config { DynamicRecordSizingDisabled: c.DynamicRecordSizingDisabled, Renegotiation: c.Renegotiation, KeyLogWriter: c.KeyLogWriter, - sessionTicketKeys: sessionTicketKeys, + sessionTicketKeys: c.sessionTicketKeys, + autoSessionTicketKeys: c.autoSessionTicketKeys, } } -// serverInit is run under c.serverInitOnce to do initialization of c. If c was -// returned by a GetConfigForClient callback then the argument should be the -// Config that was passed to Server, otherwise it should be nil. -func (c *Config) serverInit(originalConfig *Config) { - if c.SessionTicketsDisabled || len(c.ticketKeys()) != 0 { +// deprecatedSessionTicketKey is set as the prefix of SessionTicketKey if it was +// randomized for backwards compatibility but is not in use. +var deprecatedSessionTicketKey = []byte("DEPRECATED") + +// initLegacySessionTicketKeyRLocked ensures the legacy SessionTicketKey field is +// randomized if empty, and that sessionTicketKeys is populated from it otherwise. +func (c *Config) initLegacySessionTicketKeyRLocked() { + // Don't write if SessionTicketKey is already defined as our deprecated string, + // or if it is defined by the user but sessionTicketKeys is already set. + if c.SessionTicketKey != [32]byte{} && + (bytes.HasPrefix(c.SessionTicketKey[:], deprecatedSessionTicketKey) || len(c.sessionTicketKeys) > 0) { return } - alreadySet := false - for _, b := range c.SessionTicketKey { - if b != 0 { - alreadySet = true - break + // We need to write some data, so get an exclusive lock and re-check any conditions. + c.mutex.RUnlock() + defer c.mutex.RLock() + c.mutex.Lock() + defer c.mutex.Unlock() + if c.SessionTicketKey == [32]byte{} { + if _, err := io.ReadFull(c.rand(), c.SessionTicketKey[:]); err != nil { + panic(fmt.Sprintf("tls: unable to generate random session ticket key: %v", err)) } + // Write the deprecated prefix at the beginning so we know we created + // it. This key with the DEPRECATED prefix isn't used as an actual + // session ticket key, and is only randomized in case the application + // reuses it for some reason. + copy(c.SessionTicketKey[:], deprecatedSessionTicketKey) + } else if !bytes.HasPrefix(c.SessionTicketKey[:], deprecatedSessionTicketKey) && len(c.sessionTicketKeys) == 0 { + c.sessionTicketKeys = []ticketKey{c.ticketKeyFromBytes(c.SessionTicketKey)} } - if !alreadySet { - if originalConfig != nil { - copy(c.SessionTicketKey[:], originalConfig.SessionTicketKey[:]) - } else if _, err := io.ReadFull(c.rand(), c.SessionTicketKey[:]); err != nil { - c.SessionTicketsDisabled = true - return +} + +// ticketKeys returns the ticketKeys for this connection. +// If configForClient has explicitly set keys, those will +// be returned. Otherwise, the keys on c will be used and +// may be rotated if auto-managed. +// During rotation, any expired session ticket keys are deleted from +// c.sessionTicketKeys. If the session ticket key that is currently +// encrypting tickets (ie. the first ticketKey in c.sessionTicketKeys) +// is not fresh, then a new session ticket key will be +// created and prepended to c.sessionTicketKeys. +func (c *Config) ticketKeys(configForClient *Config) []ticketKey { + // If the ConfigForClient callback returned a Config with explicitly set + // keys, use those, otherwise just use the original Config. + if configForClient != nil { + configForClient.mutex.RLock() + if configForClient.SessionTicketsDisabled { + return nil } + configForClient.initLegacySessionTicketKeyRLocked() + if len(configForClient.sessionTicketKeys) != 0 { + ret := configForClient.sessionTicketKeys + configForClient.mutex.RUnlock() + return ret + } + configForClient.mutex.RUnlock() } - if originalConfig != nil { - originalConfig.mutex.RLock() - c.sessionTicketKeys = originalConfig.sessionTicketKeys - originalConfig.mutex.RUnlock() - } else { - c.sessionTicketKeys = []ticketKey{ticketKeyFromBytes(c.SessionTicketKey)} + c.mutex.RLock() + defer c.mutex.RUnlock() + if c.SessionTicketsDisabled { + return nil + } + c.initLegacySessionTicketKeyRLocked() + if len(c.sessionTicketKeys) != 0 { + return c.sessionTicketKeys + } + // Fast path for the common case where the key is fresh enough. + if len(c.autoSessionTicketKeys) > 0 && c.time().Sub(c.autoSessionTicketKeys[0].created) < ticketKeyRotation { + return c.autoSessionTicketKeys } -} -func (c *Config) ticketKeys() []ticketKey { - c.mutex.RLock() - // c.sessionTicketKeys is constant once created. SetSessionTicketKeys - // will only update it by replacing it with a new value. - ret := c.sessionTicketKeys + // autoSessionTicketKeys are managed by auto-rotation. c.mutex.RUnlock() - return ret + defer c.mutex.RLock() + c.mutex.Lock() + defer c.mutex.Unlock() + // Re-check the condition in case it changed since obtaining the new lock. + if len(c.autoSessionTicketKeys) == 0 || c.time().Sub(c.autoSessionTicketKeys[0].created) >= ticketKeyRotation { + var newKey [32]byte + if _, err := io.ReadFull(c.rand(), newKey[:]); err != nil { + panic(fmt.Sprintf("unable to generate random session ticket key: %v", err)) + } + valid := make([]ticketKey, 0, len(c.autoSessionTicketKeys)+1) + valid = append(valid, c.ticketKeyFromBytes(newKey)) + for _, k := range c.autoSessionTicketKeys { + // While rotating the current key, also remove any expired ones. + if c.time().Sub(k.created) < ticketKeyLifetime { + valid = append(valid, k) + } + } + c.autoSessionTicketKeys = valid + } + return c.autoSessionTicketKeys } -// SetSessionTicketKeys updates the session ticket keys for a server. The first -// key will be used when creating new tickets, while all keys can be used for -// decrypting tickets. It is safe to call this function while the server is -// running in order to rotate the session ticket keys. The function will panic -// if keys is empty. +// SetSessionTicketKeys updates the session ticket keys for a server. +// +// The first key will be used when creating new tickets, while all keys can be +// used for decrypting tickets. It is safe to call this function while the +// server is running in order to rotate the session ticket keys. The function +// will panic if keys is empty. +// +// Calling this function will turn off automatic session ticket key rotation. +// +// If multiple servers are terminating connections for the same host they should +// all have the same session ticket keys. If the session ticket keys leaks, +// previously recorded and future TLS connections using those keys might be +// compromised. func (c *Config) SetSessionTicketKeys(keys [][32]byte) { if len(keys) == 0 { panic("tls: keys must have at least one key") @@ -753,7 +882,7 @@ func (c *Config) SetSessionTicketKeys(keys [][32]byte) { newKeys := make([]ticketKey, len(keys)) for i, bytes := range keys { - newKeys[i] = ticketKeyFromBytes(bytes) + newKeys[i] = c.ticketKeyFromBytes(bytes) } c.mutex.Lock() @@ -1264,13 +1393,6 @@ func (c *lruSessionCache) Get(sessionKey string) (*ClientSessionState, bool) { 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 { |