fix: reject service messages while keying - #1200
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Pull request overview
This PR enforces RFC 4253 §7.1 by rejecting SERVICE_REQUEST / SERVICE_ACCEPT messages that arrive while a key exchange (initial KEX or rekey) is in flight, using ssh->isKeying as the definitive signal rather than relying only on acceptState / connectState.
Changes:
- Block
MSGID_SERVICE_REQUESTon the server side whenssh->isKeyingis set. - Block
MSGID_SERVICE_ACCEPTon the client side whenssh->isKeyingis set. - Add regression tests covering both the direct “IsMessageAllowed” path and the full receive path during rekey.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
src/internal.c |
Adds isKeying-based gating for service messages to comply with RFC 4253 §7.1 during rekey/keying windows. |
tests/regress.c |
Adds unit + receive-path regression coverage to ensure service messages are rejected during keying and accepted afterward. |
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RFC 4253 section 7.1 bars SERVICE_REQUEST and SERVICE_ACCEPT between a KEXINIT and the matching NEWKEYS. The admission check now consults ssh->isKeying, which acceptState and connectState do not track. It tests WOLFSSH_PEER_IS_KEYING, as the KEXINIT gate below it does: a peer that has not seen our KEXINIT yet may still legally send. - gate MSGID_SERVICE_REQUEST on isKeying in IsMessageAllowedServer() - gate MSGID_SERVICE_ACCEPT on isKeying in IsMessageAllowedClient() - record the refusals as WS_MSGID_NOT_ALLOWED_E, the code DoReceive() stores anyway, rather than WS_REKEYING, a soft retry-later status - add unit and receive-path coverage in tests/regress.c Issue: F-10569
ejohnstown
requested review from
wolfSSL-Fenrir-bot
and removed request for
wolfSSL-Fenrir-bot
August 27, 2026 20:53
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Fenrir Automated Review — PR #1200
Scan targets checked: wolfssh-bugs, wolfssh-src
Fenrir result: Approved ✅
No new issues found in the changed files.
Advisory only — this automated result does not count as a GitHub approval.
philljj
approved these changes
Aug 28, 2026
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RFC 4253 section 7.1 bars SERVICE_REQUEST and SERVICE_ACCEPT between a
KEXINIT and the matching NEWKEYS. The admission check now consults
ssh->isKeying, which acceptState and connectState do not track.
Issue: F-10569