9d75dce3e1
Add SSL_verify_client_post_handshake() for servers to initiate PHA Add SSL_force_post_handshake_auth() for clients that don't have certificates initially configured, but use a certificate callback. Update SSL_CTX_set_verify()/SSL_set_verify() mode: * Add SSL_VERIFY_POST_HANDSHAKE to postpone client authentication until after the initial handshake. * Update SSL_VERIFY_CLIENT_ONCE now only sends out one CertRequest regardless of when the certificate authentication takes place; either initial handshake, re-negotiation, or post-handshake authentication. Add 'RequestPostHandshake' and 'RequirePostHandshake' SSL_CONF options that add the SSL_VERIFY_POST_HANDSHAKE to the 'Request' and 'Require' options Add support to s_client: * Enabled automatically when cert is configured * Can be forced enabled via -force_pha Add support to s_server: * Use 'c' to invoke PHA in s_server * Remove some dead code Update documentation Update unit tests: * Illegal use of PHA extension * TLSv1.3 certificate tests DTLS and TLS behave ever-so-slightly differently. So, when DTLS1.3 is implemented, it's PHA support state machine may need to be different. Add a TODO and a #error Update handshake context to deal with PHA. The handshake context for TLSv1.3 post-handshake auth is up through the ClientFinish message, plus the CertificateRequest message. Subsequent Certificate, CertificateVerify, and Finish messages are based on this handshake context (not the Certificate message per se, but it's included after the hash). KeyUpdate, NewSessionTicket, and prior Certificate Request messages are not included in post-handshake authentication. After the ClientFinished message is processed, save off the digest state for future post-handshake authentication. When post-handshake auth occurs, copy over the saved handshake context into the "main" handshake digest. This effectively discards the any KeyUpdate or NewSessionTicket messages and any prior post-handshake authentication. This, of course, assumes that the ID-22 did not mean to include any previous post-handshake authentication into the new handshake transcript. This is implied by section 4.4.1 that lists messages only up to the first ClientFinished. Reviewed-by: Ben Kaduk <kaduk@mit.edu> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/4964) |
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|---|---|---|
| .. | ||
| extensions.c | ||
| extensions_clnt.c | ||
| extensions_cust.c | ||
| extensions_srvr.c | ||
| README | ||
| statem.c | ||
| statem.h | ||
| statem_clnt.c | ||
| statem_dtls.c | ||
| statem_lib.c | ||
| statem_locl.h | ||
| statem_srvr.c | ||
State Machine Design
====================
This file provides some guidance on the thinking behind the design of the
state machine code to aid future maintenance.
The state machine code replaces an older state machine present in OpenSSL
versions 1.0.2 and below. The new state machine has the following objectives:
- Remove duplication of state code between client and server
- Remove duplication of state code between TLS and DTLS
- Simplify transitions and bring the logic together in a single location
so that it is easier to validate
- Remove duplication of code between each of the message handling functions
- Receive a message first and then work out whether that is a valid
transition - not the other way around (the other way causes lots of issues
where we are expecting one type of message next but actually get something
else)
- Separate message flow state from handshake state (in order to better
understand each)
- message flow state = when to flush buffers; handling restarts in the
event of NBIO events; handling the common flow of steps for reading a
message and the common flow of steps for writing a message etc
- handshake state = what handshake message are we working on now
- Control complexity: only the state machine can change state: keep all
the state changes local to the state machine component
The message flow state machine is divided into a reading sub-state machine and a
writing sub-state machine. See the source comments in statem.c for a more
detailed description of the various states and transitions possible.
Conceptually the state machine component is designed as follows:
libssl
|
---------------------------|-----statem.h--------------------------------------
|
_______V____________________
| |
| statem.c |
| |
| Core state machine code |
|____________________________|
statem_locl.h ^ ^
_________| |_______
| |
_____________|____________ _____________|____________
| | | |
| statem_clnt.c | | statem_srvr.c |
| | | |
| TLS/DTLS client specific | | TLS/DTLS server specific |
| state machine code | | state machine code |
|__________________________| |__________________________|
| |_______________|__ |
| ________________| | |
| | | |
____________V_______V________ ________V______V_______________
| | | |
| statem_both.c | | statem_dtls.c |
| | | |
| Non core functions common | | Non core functions common to |
| to both servers and clients | | both DTLS servers and clients |
|_____________________________| |_______________________________|