4 ms·

Very useful, depending on the implementation and potential trade-offs. If the performance is good, this is a nice extra layer that makes return-oriented program

Very useful, depending on the implementation and potential trade-offs. If the performance is good, this is a nice extra layer that makes return-oriented programming more difficult. Combined with NX bits, it really raises the difficulty in developing/using many types of exploits. (it's not impossible to bypass, I'm vaguely aware it's been done on Apple's new chips that implement a similar (the same?) ARM extension, but there's no perfect security)

pram 5y ago
Yup arm64e in general has pointer authentication, iOS and MacOS already implement it.
- philistine 5y ago
  It's incredible how Apple went from a laggard in new technologies to a trailblazer. I guess that's the power of a corporation on the scale of an 18th century trade monopoly.
  - pjmlp 5y ago
    Except Oracle did it first with SPARC ADI, Solaris on SPARC is one of the few UNIXes that have tamed C for couple of years now. And actually pointer tagging architectures go all the way back to the early 1960's, with Burroughs being one of the first ones having a go at it.
    - zokier 5y ago
      It's not much of trailblazing if nobody follows on the trail.
      - pjmlp 5y ago
        Indeed, Apple is following the trail of Burroughs, iAPX 432, MPX, SPARC ADI, Lisp Machines, among others.
Accujack 5y ago
Performance is what I wonder about. The idea sounds good, but what crypto scheme can perform encryption of a signature both securely and fast enough to keep up with every pointer pushed on the stack? What's the trade-off?
- staticassertion 5y ago
  > but what crypto scheme can perform encryption of a signature both securely and fast enough XOR, I assume. https://pure.tugraz.at/ws/portalfiles/portal/37604654/ind_branch_faults_pa_2021_nasahl_host.pdf https://pure.tugraz.at/ws/portalfiles/portal/37604654/ind_br... > On average, encoding addresses and verifying them at each indirect branch using the dedicated blraaz and braaz instructions yields a performance overhead of 1.50%. The protection of the link between indirect control-flow transfers induces a runtime overhead of 0.83% on average. For the combination of both protection mechanism, we measured an average performance overhead of 2.34%.
  - my123 5y ago
    https://eprint.iacr.org/2016/444.pdf https://eprint.iacr.org/2016/444.pdf is the cipher used for pointer auth on Arm-designed cores.
    - staticassertion 5y ago
      Wonderful, thank you.

pram 5y ago

Yup arm64e in general has pointer authentication, iOS and MacOS already implement it.

philistine 5y ago
It's incredible how Apple went from a laggard in new technologies to a trailblazer. I guess that's the power of a corporation on the scale of an 18th century trade monopoly.
- pjmlp 5y ago
  Except Oracle did it first with SPARC ADI, Solaris on SPARC is one of the few UNIXes that have tamed C for couple of years now. And actually pointer tagging architectures go all the way back to the early 1960's, with Burroughs being one of the first ones having a go at it.
  - zokier 5y ago
    It's not much of trailblazing if nobody follows on the trail.
    - pjmlp 5y ago
      Indeed, Apple is following the trail of Burroughs, iAPX 432, MPX, SPARC ADI, Lisp Machines, among others.

Accujack 5y ago

Performance is what I wonder about. The idea sounds good, but what crypto scheme can perform encryption of a signature both securely and fast enough to keep up with every pointer pushed on the stack? What's the trade-off?

staticassertion 5y ago
> but what crypto scheme can perform encryption of a signature both securely and fast enough XOR, I assume. https://pure.tugraz.at/ws/portalfiles/portal/37604654/ind_branch_faults_pa_2021_nasahl_host.pdf https://pure.tugraz.at/ws/portalfiles/portal/37604654/ind_br... > On average, encoding addresses and verifying them at each indirect branch using the dedicated blraaz and braaz instructions yields a performance overhead of 1.50%. The protection of the link between indirect control-flow transfers induces a runtime overhead of 0.83% on average. For the combination of both protection mechanism, we measured an average performance overhead of 2.34%.
- my123 5y ago
  https://eprint.iacr.org/2016/444.pdf https://eprint.iacr.org/2016/444.pdf is the cipher used for pointer auth on Arm-designed cores.
  - staticassertion 5y ago
    Wonderful, thank you.