tomaswolf commented on code in PR #449: URL: https://github.com/apache/mina-sshd/pull/449#discussion_r1442294794
########## sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractSession.java: ########## @@ -2056,11 +2128,33 @@ protected Map<KexProposalOption, String> negotiate() throws Exception { Map<KexProposalOption, String> s2cOptions = getServerKexProposals(); signalNegotiationStart(c2sOptions, s2cOptions); + // Make modifiable. Strict KEX flags are to be heeded only in initial KEX, and to be ignored afterwards. + c2sOptions = new EnumMap<>(c2sOptions); + s2cOptions = new EnumMap<>(s2cOptions); + boolean strictKexClient = removeValue(c2sOptions, KexProposalOption.ALGORITHMS, + KexExtensions.STRICT_KEX_CLIENT_EXTENSION); + boolean strictKexServer = removeValue(s2cOptions, KexProposalOption.ALGORITHMS, + KexExtensions.STRICT_KEX_SERVER_EXTENSION); + // Make unmodifiable again + c2sOptions = Collections.unmodifiableMap(c2sOptions); + s2cOptions = Collections.unmodifiableMap(s2cOptions); Map<KexProposalOption, String> guess = new EnumMap<>(KexProposalOption.class); Map<KexProposalOption, String> negotiatedGuess = Collections.unmodifiableMap(guess); try { boolean debugEnabled = log.isDebugEnabled(); boolean traceEnabled = log.isTraceEnabled(); + if (!initialKexDone) { + strictKex = strictKexClient && strictKexServer; + if (debugEnabled) { + log.debug("negotiate({}) strict KEX={} client={} server={}", this, strictKex, strictKexClient, + strictKexServer); + } + if (strictKex && initialKexInitSequenceNumber != 1) { + throw new SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED, + "Strict KEX negotiated but sequence number of first KEX_INIT received is not 1: " + + initialKexInitSequenceNumber); + } + } Review Comment: Done. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: dev-unsubscr...@mina.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@mina.apache.org For additional commands, e-mail: dev-h...@mina.apache.org