e4138f2014-10-07Henrik Grubbström (Grubba) Pike SSL/TLS Implementation Notes ================================= SSL/TLS Standard Documents and Amount of Coverage ------------------------------------------------- SSL and TLS are specified in quite a few documents; the following is an attempt to list them all, and the level of implementation in Pike. Legend: [ ] Not implemented at present. [-] Not implemented and will not be implemented. Typically an obsolete or insecure standard. [/] Partially implemented. [X] Fully implemented. NB: Constants from documents marked as not implemented may still be added to SSL.Constants for debug purposes. The SSL 2.0 protocol was specified in the following document: [-] SSL 2.0 draft-hickman-netscape-ssl-00.txt The SSL 3.0 Protocol was specified in the following draft (later an RFC): [X] SSL 3.0 draft-freier-ssl-version3-02.txt [X] SSL 3.0 RFC 6101 The TLS 1.0 Protocol is specified in the following RFCs: [X] SSL 3.1/TLS 1.0 RFC 2246 [ ] Kerberos for TLS 1.0 RFC 2712 [X] AES Ciphers for TLS 1.0 RFC 3268 [/] Extensions for TLS 1.0 RFC 3546 [X] TLS Compression Methods RFC 3749 [ ] LZS Compression for TLS RFC 3943 [X] Camellia Cipher for TLS RFC 4132 [ ] SEED Cipher for TLS 1.0 RFC 4162 [ ] Pre-Shared Keys for TLS RFC 4279 The TLS 1.1 Protocol is specified in the following RFCs: [X] SSL 3.2/TLS 1.1 RFC 4346 [/] Extensions for TLS 1.1 RFC 4366 [X] ECC Ciphers for TLS 1.1 RFC 4492 [ ] Session Resumption RFC 4507 [ ] TLS Handshake Message RFC 4680 [ ] User Mapping Extension RFC 4681 [ ] PSK with NULL for TLS 1.1 RFC 4785 [ ] SRP with TLS 1.1 RFC 5054 [ ] Session Resumption RFC 5077 [ ] OpenPGP Authentication RFC 5081 [X] Authenticated Encryption RFC 5116 The DTLS Protocol is specified in the following RFCs: [ ] DTLS over DCCP RFC 5238 The TLS 1.2 Protocol is specified in the following RFCs: [X] SSL 3.3/TLS 1.2 RFC 5246 [X] AES GCM Cipher for TLS RFC 5288 [X] ECC with SHA256/384 & GCM RFC 5289 [/] Suite B Profile for TLS RFC 5430 [ ] DES and IDEA for TLS RFC 5469 [ ] Pre-Shared Keys with GCM RFC 5487 [ ] ECDHA_PSK Cipher for TLS RFC 5489 [ ] Renegotiation Extension RFC 5746 [ ] Authorization Extensions RFC 5878 [X] Camellia Cipher for TLS RFC 5932 [ ] KeyNote Auth for TLS RFC 6042 [ ] TLS Extension Definitions RFC 6066 [ ] OpenPGP Authentication RFC 6091 [ ] ARIA Cipher for TLS RFC 6209 [ ] Additional Master Secrets RFC 6358 [X] Camellia Cipher for TLS RFC 6367 [/] Suite B Profile for TLS RFC 6460 [X] Heartbeat Extension RFC 6520 [X] AES-CCM Cipher for TLS RFC 6655 [ ] Multiple Certificates RFC 6961 [ ] Certificate Transparency RFC 6962 [ ] ECC Brainpool Curves RFC 7027 [ ] Raw Public Keys in (D)TLS RFC 7250 [X] AES-CCM ECC Suites for TLS RFC 7251 [X] TLS ALPN Extension RFC 7301 [X] TLS Encrypt-then-MAC RFC 7366 Drafts (in order of age, oldest first): [/] 56-bit Export Cipher draft-ietf-tls-56-bit-ciphersuites-01.txt [-] Next Protocol Negotiation draft-agl-tls-nextprotoneg [ ] Chacha20Poly1305 draft-agl-tls-chacha20poly1305-02.txt [/] TLS Padding draft-agl-tls-padding [X] TLS Fallback SCSV draft-ietf-tls-downgrade-scsv-00.txt [ ] SSL 3.4/TLS 1.3 draft-ietf-tls-tls13-02.txt [ ] Prohibit RC4 draft-ietf-tls-prohibiting-rc4 The TLS parameters registry: http://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml SSL.File and Stdio.File Emulation Overview ------------------------------------------ Stream: The underlying stream object is always in nonblocking mode, to avoid risk of hanging in Stdio.Buffer. Buffering: All I/O-ops are always buffered with Stdio.Buffer. Internal Callback Handling in Nonblocking Mode: In nonblocking mode all internal callback handling is performed directly with the real_backend. If the main backend has been started (ie master()->asyncp() is true), we assume that it will handle I/O. Otherwise if nonthreaded or we are on the backend thread (master()->backend_thread()), we rotate the real_backend once with 0.0 timeout per I/O-op. Note that this may cause problems when using custom backends without having started the main backend. Detect? Internal Callback Handling in Blocking Mode: In blocking mode all internal callback handling is performed with a dedicated local_backend. The local_backend is created when the SSL.File is switched to blocking mode. The local_backend is then rotated until the blocking call is done. User Callback Handling: All user installed callbacks are called via call_out() on internal_poll() in the real_backend. read(): Get data from user_read_buffer, install ssl_read_callback on underflow. In blocking mode rotate the local backend until all data is available. In nonblocking mode attempt to rotate the local backend once if no callbacks are installed. write(): Fill write_buffer, install ssl_write_callback. In blocking mode rotate the local backend until the write_buffer is empty. In nonblocking mode attempt to rotate the local backend once if no callbacks are installed. close(): Schedule a close packet, and block further calls to write. If both directions block also further calls to read. Install both ssl_write_callback and ssl_read_callback and rotate the local backend until connection closed from other end, or linger time expires. ssl_read_callback(): Decode received data and add it to user_read_buffer. Schedule read_callback with real_backend call_out. Uninstall on user_read_buffer full. ssl_write_callback(): Send data from write_buffer, uninstall on write_buffer empty. Schedule write_callback with real_backend call_out. On send failure, block futher calls of write. ssl_close_callback(): Schedule close_callback if close() has not been called yet. Block further calls of read. ssl_close_alert_callback(): As ssl_close_callback, but allow use of stream when done. Known Problems: Nonblocking mode without callbacks. Support for set_buffer_mode() et al not yet supported, neither directly nor in the embedded stream.