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CET-IBT

Architecture referenceFeex

CET-IBT na indirect branch tracking, control-flow protection wey dey check di target dem of tracked indirect call dem and jump dem. E dey separate from CET shadow stacks.

Wetin you need know

CET-IBT na indirect branch tracking, control-flow protection wey dey check di target dem of tracked indirect call dem and jump dem. E dey separate from CET shadow stacks.

How e dey work

Wen tracking dey enabled for di applicable execution environment, indirect transfer must reach appropriate ENDBR landing instruction under di architecture im rule dem. Di mechanism dey use architectural tracking state and e dey raise control-protection exception wen dem violate di contract. Compiler and binary instrumentation dey part of deployment.

Where e dey useful

Compiler fit mark valid indirect-entry location dem inside library. Di OS and runtime must apply compatible enablement and policy to di code wey dey execute. To see ENDBR byte dem inside disassembly no dey prove, by imself, say di system currently dey enforce IBT.

How to check support and enablement

CPUID.07H.00H:EDX bit 20 dey enumerate IBT capability. Check di OS im user/supervisor support and binary policy separately. Diagnose compatibility using official compiler and OS guidance instead of removing landing instruction dem from binary.

Capability, enablement and enforcement na different ting dem wey person must check separately. Processor fit support protection while di OS, application or virtual-machine policy no turn am on. Database support field no be attestation say running system dey secure.

Wetin di feature no dey guarantee

IBT no dey check normal function return dem di way shadow stack dem dey do. E no be guarantee for complete control-flow integrity or application safety, and support for shadow stacks no dey establish IBT support.

Compatibility and performance inside real life

Keep di OS, firmware and affected runtime current. If protection show compatibility problem, make you use vendor diagnostics and supported update dem first. Broad protection toggle fit affect oda application dem wey no concern am, so e suppose follow clear deployment and recovery policy.

Practical verification checklist

  1. Record di exact processor or platform model plus di application, OS and runtime version dem wey dey involve. Make you keep di exact word dem wey di error or requirement use.
  2. Check di manufacturer reference for dat exact model, den inspect di real capability and enabled state inside di environment where di program dey run.
  3. Compare every single requirement of di binary or backend wey you choose. Name wey resemble am, alias, or broad technology label no reach.
  4. Confirm say di application select di implementation wey dem intend. Use di diagnostics wey dem document and supported fallback if requirement dem no complete.
  5. Make only one supported change at a time, den run di same workload again. Keep di original configuration and recovery way ready.

If dem list di feature but software no fit use am

Start from di exact component wey dey fail. Hardware database dey describe capability wey dem record; di operating system or hypervisor fit show different real environment. If illegal-instruction error happen, you still need to check di exact instruction wey cause di fault and di binary build, because corrupt file or anoda instruction wey no dey supported fit give di same kind problem.

Install di application, driver or runtime version wey get support for dat exact platform, and use di vendor documented baseline or fallback build if e need am. Software update no fit create instruction wey di processor no get. Firmware and security-policy change dem suppose follow di system manufacturer procedure and recovery plan, no be just any common optimization advice.

Sources and scope of dis explanation

Intel 64 and IA-32 Architectures Software Developer's Manual · Linux kernel: Control-flow Enforcement Technology shadow stack

Dis reference dem establish architectural behavior and software requirement dem. Dem no dey independently verify every feature value for any linked hardware model page. For model support, use dat page manufacturer evidence and check di active system configuration. Dis article no supply benchmark, certification or independent review date.

Sources and verification

Editorial ownership: Feex. No independent review date dey recorded. How we dey do research.

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