Ensure the ECDSA signature scheme is bound to the certificate curve. Always validate MFL for TLS 1.3, even when WOLFSSL_OLD_UNSUPPORTED_EXTENSION is defined.

[kareem-wolfssl]

Description

Fixes zd#22471, F-11837

Thanks to Eva Crystal (0xiviel), XSource Security for the ECDSA report!

Testing

Built in/added tests, provided reproducer

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[Copilot]

🟡 Changes recommended

The ECDSA validation compares curve sizes rather than exact curve identities, allowing same-sized mismatched curves.

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Pull request overview

Strengthens TLS 1.3 validation for ECDSA signature schemes and Maximum Fragment Length responses.

Changes:

• Validates peer ECDSA certificate curves during CertificateVerify.
• Enforces TLS 1.3 MFL validation despite legacy extension handling.
• Adds regression tests for both behaviors.

File summaries

File	Description
wolfssl/internal.h	Exposes the ECC strength comparison helper.
src/internal.c	Makes the ECC helper externally accessible.
src/tls13.c	Adds ECDSA curve validation.
src/tls.c	Enforces TLS 1.3 MFL response checks.
tests/api/test_tls13.c	Tests ECDSA scheme/curve mismatches.
tests/api/test_tls13.h	Registers the new TLS 1.3 test.
tests/api/test_tls_parse.c	Tests TLS 1.3 MFL validation.

Review details

• Files reviewed: 7/7 changed files
• Comments generated: 1
• Review effort level: Balanced

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[github-actions]

MemBrowse Memory Report

gcc-arm-cortex-m4-dtls13

• FLASH: .text +64 B (+0.0%, 188,668 B / 1,048,576 B, total: 18% used)

gcc-arm-cortex-m4-openssl-compat

• FLASH: .rodata +8 B, .text +64 B (+0.0%, 786,284 B / 1,048,576 B, total: 75% used)

gcc-arm-cortex-m4-pq

• FLASH: .text +128 B (+0.0%, 303,696 B / 1,048,576 B, total: 29% used)

gcc-arm-cortex-m4-tls13

• FLASH: .text +128 B (+0.1%, 244,119 B / 262,144 B, total: 93% used)

gcc-arm-cortex-m7-pq

• FLASH: .text +128 B (+0.0%, 304,592 B / 1,048,576 B, total: 29% used)

gcc-arm-cortex-m7-tls13

• FLASH: .text +64 B (+0.0%, 244,119 B / 262,144 B, total: 93% used)

linuxkm-standard

• Data: __patchable_function_entries +16 B (+0.0%, 50,616 B)
  No memory changes detected for:
• gcc-arm-cortex-m0plus
• gcc-arm-cortex-m3
• gcc-arm-cortex-m4
• gcc-arm-cortex-m4-baremetal
• gcc-arm-cortex-m4-crypto-only
• gcc-arm-cortex-m4-min-ecc
• gcc-arm-cortex-m4-pkcs7
• gcc-arm-cortex-m4-rsa-only
• gcc-arm-cortex-m4-sp-math
• gcc-arm-cortex-m4-tls12
• gcc-arm-cortex-m7
• linuxkm-pie
• stm32-sim-stm32h753