[TLS 1.3] FIX: Record Layer must handle multiple records in compatibility mode#3064
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[TLS 1.3] FIX: Record Layer must handle multiple records in compatibility mode#3064
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lieser
reviewed
Nov 7, 2022
RFC 8446 5.1
legacy_record_version: MUST be set to 0x0303 for all records
generated by a TLS 1.3 implementation other than an initial
ClientHello [...] where it MAY also be 0x0301 for compatibility
purposes.
If said Client Hello spans multiple records the above rule applies
to all of them. Hence, `Record_Layer` cannot handle this state
internally but must depend on its upstream user.
If the client responds with an Alert to the Server Hello, it must not send a compatibility-mode dummy CCS. The respective BoGo test was inadvertantly disabled.
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Codecov ReportBase: 92.59% // Head: 92.56% // Decreases project coverage by
Additional details and impacted files@@ Coverage Diff @@
## master #3064 +/- ##
==========================================
- Coverage 92.59% 92.56% -0.04%
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Files 602 602
Lines 70623 70650 +27
Branches 6666 6662 -4
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+ Hits 65396 65398 +2
- Misses 5197 5222 +25
Partials 30 30
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lieser
approved these changes
Nov 10, 2022
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If said Client Hello spans multiple records the above rule applies to all of them. Hence,
Record_Layercannot handle this state internally but must depend on its upstream user.This introduces
m_first_message_sentandm_first_message_receivedat the TLS 1.3 channel level and disables the compatibility mode in theRecord_Layeraccordingly.Furthermore, another "compatibility mode" issue is fixed. Clients must not send a dummy Change Cipher Spec message prior to their second flight if this record is an unprotected Alert. The BoGo test that would have revealed that was disabled by accident.
I found these issues when starting to run BoGo server tests against the upcoming TLS 1.3 server implementation.