Reject certificates with trailing data. Avoid copying trailing data to WOLFSSL_X509 structs.

[kareem-wolfssl]

Description

Fixes zd#22010

Testing

Provided reproducer, built-in tests

Checklist

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

[Copilot]

Pull request overview

This PR tightens X.509 parsing behavior to prevent accepting and re-emitting certificates that have extra trailing bytes beyond the certificate’s outer ASN.1 SEQUENCE, while preserving support for OpenSSL/RFC “TRUSTED CERTIFICATE” blobs that legitimately carry auxiliary trust data after the cert.

Changes:

• Add strict-mode detection/rejection of trailing bytes after the certificate’s outer SEQUENCE (with an internal opt-out for TRUSTED_CERT_TYPE).
• Ensure WOLFSSL_X509 DER storage never includes trailing bytes by truncating copies to the parsed outer-SEQUENCE end.
• Adjust TRUSTED_CERT_TYPE handling to be recognized centrally in ParseCertRelative and fix an API test to use the actual DER length.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
wolfssl/wolfcrypt/asn.h	Adds DecodedCert.allowTrailing bit to permit trusted-cert auxiliary trailing data internally.
wolfcrypt/src/asn.c	Rejects trailing bytes in strict builds; centralizes TRUSTED_CERT_TYPE handling to allow aux trailing data.
tests/api.c	Fixes a test to use the returned DER length (avoids unintended trailing bytes).
src/x509.c	Uses ParseCertRelative’s TRUSTED_CERT_TYPE handling and clarifies trusted-cert truncation behavior.
src/internal.c	Truncates stored DER in X509/ACERT objects to the end of the outer SEQUENCE (prevents re-emitting trailing bytes).

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[github-actions]

MemBrowse Memory Report

gcc-arm-cortex-m0plus

• FLASH: .text +84 B (+0.1%, 63,579 B / 262,144 B, total: 24% used)

gcc-arm-cortex-m3

• FLASH: .text +48 B (+0.0%, 121,457 B / 262,144 B, total: 46% used)

gcc-arm-cortex-m4

• FLASH: .text +64 B (+0.0%, 199,116 B / 262,144 B, total: 76% used)

gcc-arm-cortex-m4-baremetal

• FLASH: .text +64 B (+0.1%, 66,123 B / 262,144 B, total: 25% used)

gcc-arm-cortex-m4-crypto-only

• FLASH: .text +64 B (+0.0%, 173,738 B / 262,144 B, total: 66% used)

gcc-arm-cortex-m4-dtls13

• FLASH: .text +64 B (+0.0%, 179,864 B / 1,048,576 B, total: 17% used)

gcc-arm-cortex-m4-min-ecc

• FLASH: .text +64 B (+0.1%, 61,101 B / 262,144 B, total: 23% used)

gcc-arm-cortex-m4-openssl-compat

• FLASH: .text +128 B (+0.0%, 768,260 B / 1,048,576 B, total: 73% used)

gcc-arm-cortex-m4-pkcs7

• FLASH: .text +64 B (+0.0%, 211,437 B / 262,144 B, total: 81% used)

gcc-arm-cortex-m4-pq

• FLASH: .text +64 B (+0.0%, 278,000 B / 1,048,576 B, total: 27% used)

gcc-arm-cortex-m4-rsa-only

• FLASH: .text +64 B (+0.0%, 323,536 B / 1,048,576 B, total: 31% used)

gcc-arm-cortex-m4-sp-math

• FLASH: .text +64 B (+0.1%, 61,101 B / 262,144 B, total: 23% used)

gcc-arm-cortex-m4-tls13

• FLASH: .text +64 B (+0.0%, 234,750 B / 262,144 B, total: 90% used)

gcc-arm-cortex-m7

• FLASH: .text +64 B (+0.0%, 199,116 B / 262,144 B, total: 76% used)

gcc-arm-cortex-m7-pq

• FLASH: .text +64 B (+0.0%, 278,576 B / 1,048,576 B, total: 27% used)

gcc-arm-cortex-m7-tls13

• FLASH: .text +64 B (+0.0%, 234,814 B / 262,144 B, total: 90% used)

stm32-sim-stm32h753

• FLASH: .text +64 B (+0.0%, 181,748 B / 2,097,152 B, total: 9% used)
  No memory changes detected for:
• gcc-arm-cortex-m4-tls12
• linuxkm-pie
• linuxkm-standard