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Re: Constant Stack Canaries

From scott@slp53.sl.home (Scott Lurndal)
Subject Re: Constant Stack Canaries
Newsgroups comp.arch
References (7 earlier) <vsmg8a$16gr3$1@dont-email.me> <vsnksc$2fkk9$1@dont-email.me> <6a77fabdb64f59e4497ef3353d747441@www.novabbs.org> <vsq91i$18k1q$1@dont-email.me> <760b3834d1202502f5f63e52b51cfdc8@www.novabbs.org>
Message-ID <kGeIP.467285$d51.395138@fx46.iad> (permalink)
Organization UsenetServer - www.usenetserver.com
Date 2025-04-05 18:31 +0000

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mitchalsup@aol.com (MitchAlsup1) writes:
>On Sat, 5 Apr 2025 3:45:51 +0000, Robert Finch wrote:
>

>> Would not writing to the GuestOs VAS and the application VAS be the
>> result of separate system calls? Or does the hypervisor take over for
>> the GuestOS?
>
>Application has a 64-bit VAS
>GusetOS has a 64-bit VAS
>HyprVisor has a 64-bit VAS
>and so does
>Securte has a 64-bit VAS
>
>So, we are in HV and we need to write to guestOS and to Application
>but we have only 1-bit of distinction.

On ARM64, when the HV needs to write to guest user VA or guest PA,
the SMMU provides an interface the processor can use to translate
the guest VA or Guest PA to the corresponding system physical address.
Of course, there is a race if the guest OS changes the underlying
translation tables during the upcall to the hypervisor or secure
monitor, although that would be a bug in the guest were it so to do,
since the guest explicitly requested the action from the higher
privilege level (e.g. HV).

Arm does have a set of load/store "user" instructions that translate
addresses using the unprivileged (application) translation tables.  There's
also a processor state bit (UAO - User Access Override) that can
be set to force those instructions to use the permissions associated
with the current processor privilege level.

Note that there is a push by all vendors to include support
for guest 'privacy', such that the hypervisor has no direct
access to memory owned by the guest, or where the the guest
memory is encrypted using a key the hypervisor or secure monitor
don't have access to.

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Thread

Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-03-30 08:16 -0400
  Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-30 12:47 -0500
    Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-03-30 20:14 +0000
      Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-03-30 21:26 -0400
      Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-31 01:34 -0500
      Re: Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-03-31 09:04 -0700
        Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-31 12:17 -0500
          Re: Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-03-31 10:57 -0700
          Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-03-31 18:07 +0000
            Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-31 13:56 -0500
              Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-03-31 20:52 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 00:58 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-01 18:51 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 18:06 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-01 23:24 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 20:07 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-02 01:47 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-04 21:07 +0000
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 16:21 -0500
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 18:19 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 23:04 -0500
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 14:34 -0500
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-01 23:21 +0000
                Re: Constant Stack Canaries Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-01 22:55 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 23:19 -0500
                Re: Constant Stack Canaries Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-03 10:09 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-03 12:22 -0500
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-03 23:49 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-04 12:41 -0500
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-04 21:13 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-04 23:45 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-05 16:37 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-05 18:31 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-05 17:57 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-05 23:11 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-06 14:21 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-06 15:01 -0400
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-07 14:04 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-05 23:06 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-06 14:32 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-07 00:51 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-07 14:09 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-09 00:23 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-15 00:43 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-15 14:02 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-15 20:46 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-16 14:07 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-16 21:13 +0000
                Virtualization layers (was: Constant Stack Canaries) Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-16 17:48 -0400
                Re: Virtualization layers mitchalsup@aol.com (MitchAlsup1) - 2025-04-16 22:12 +0000
                Re: Virtualization layers (was: Constant Stack Canaries) scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 00:49 +0000
                Re: Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-04-16 15:26 -0700
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 00:57 +0000
                Re: virtualization, Constant Stack Canaries John Levine <johnl@taugh.com> - 2025-04-17 01:04 +0000
                Re: virtualization, Constant Stack Canaries Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-16 21:07 -0400
                Re: virtualization, Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-04-16 23:30 -0700
                Re: virtualization, Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 13:32 +0000
                Re: virtualization, Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-17 18:22 +0000
                Re: virtualization, Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 20:10 +0000
                Re: virtualization, Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-17 21:45 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 00:47 +0000
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-02 00:43 -0500

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