[cifs-protocol] [EXTERNAL] [MS-DTYP] meaning of sign and base and range in conditional ACE integers - TrackingID#2212220040005997

[Kristian Smith]

Hi Douglas,

<Moving us to the other case thread>

I've been looking into this one trying to make sense of the sign byte and base byte as well.


Sign byte:

The signed int8 - signed int64 are setup with 2's complement. To my understanding the purpose of this is to represent negative and positive values. Adding the sign byte would negate the need for this (or vice versa). It appears that the sign byte is a sign override.

I'm currently trying to determine if we are treating the 2's complement negative and positive numbers the same and just using the sign byte.

In the example:

Thus the decimal value -1 encoded as a signed int64 would have the following binary representation (byte code, QWORD, sign byte, base byte):

0x04 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0x02 0x02
This takes a 64-bit positive '1' and negates it with the 0x02 sign byte.



Base byte:

I need to confirm this, but I believe you are correct that this is just for rendering purposes, as the math should be the same.



Integer size:

Since these are all represented by QWORDs, the size would just dictate what bytes to ignore (if any).



What I need to determine:

Does the "None" sign byte just treat the integer as positive? What's the difference between "None" and "Positive"?
Are negative and positive numbers treated the same and just overridden with the sign byte?
Is the Base byte just used to determine rendering, or does it somehow affect math/comparisons?


Let me know if we're on the same page.



Regards,
Kristian

From: Kristian Smith <Kristian.Smith at microsoft.com>
Sent: Thursday, December 29, 2022 12:17 PM
To: Douglas Bagnall <douglas.bagnall at catalyst.net.nz>; cifs-protocol at lists.samba.org
Cc: Microsoft Support <supportmail at microsoft.com>
Subject: Re: [EXTERNAL] [MS-DTYP] meaning of sign and base and range in conditional ACE integers - TrackingID#2212220040005997

Hi Douglas,

I'll be looking into this issue as well. I'll reach out when I have more information.

Thanks,
Kristian

Kristian Smith
Support Escalation Engineer
Windows Open Spec Protocols
Office: (425) 421-4442
kristian.smith at microsoft.com<mailto:kristian.smith at microsoft.com>



________________________________
From: Kristian Smith <Kristian.Smith at microsoft.com<mailto:Kristian.Smith at microsoft.com>>
Sent: Thursday, December 22, 2022 9:19 AM
To: Douglas Bagnall <douglas.bagnall at catalyst.net.nz<mailto:douglas.bagnall at catalyst.net.nz>>; cifs-protocol at lists.samba.org<mailto:cifs-protocol at lists.samba.org> <cifs-protocol at lists.samba.org<mailto:cifs-protocol at lists.samba.org>>
Cc: Interoperability Documentation Help <dochelp at microsoft.com<mailto:dochelp at microsoft.com>>
Subject: Re: [EXTERNAL] [MS-DTYP] meaning of sign and base and range in conditional ACE integers - TrackingID#2212220040005997

[DocHelp to Bcc]

Hi Douglas,

Thanks for reaching out to DocHelp regarding your [MS-DTYP] questions. I have created case 2212220040005997 so that we can look into these questions. An engineer will reach out soon.

Thank you,
Kristian


Kristian Smith

Support Escalation Engineer

Windows Open Spec Protocols

Office: (425) 421-4442

kristian.smith at microsoft.com<mailto:kristian.smith at microsoft.com>



________________________________
From: Douglas Bagnall <douglas.bagnall at catalyst.net.nz<mailto:douglas.bagnall at catalyst.net.nz>>
Sent: Wednesday, December 21, 2022 6:16 PM
To: cifs-protocol at lists.samba.org<mailto:cifs-protocol at lists.samba.org> <cifs-protocol at lists.samba.org<mailto:cifs-protocol at lists.samba.org>>; Interoperability Documentation Help <dochelp at microsoft.com<mailto:dochelp at microsoft.com>>
Subject: [EXTERNAL] [MS-DTYP] meaning of sign and base and range in conditional ACE integers

hi Dochelp,

In MS-DTYP 2.4.4.17.5 literal integers are encoded as a 64 bit number,
followed by a byte for sign and a byte for base. The range of the
integer is indicated by the token bytecode.

I don't understand how the sign and base are used.

In the example at the bottom of section 2.4.4.17.5 a negative number is
encoded with sign 'None' and base 10. What would be different in
practice if it were encoded with a different base or sign? Would it
compare differently?

As far as I can tell, the only use of integer literal tokens is in
binary relational operators. The documentation for these operators
(2.4.4.17.6) says things like

> MUST evaluate to TRUE if the argument on the RHS evaluates to the exact value
> (single or set value) of the argument on the LHS; otherwise, FALSE.

but it doesn't define how the evaluation works with the sign, base, and
range.

In conventional mathematics octal 03 == decimal 3 == hex 0x03. Does this
hold for conditional ACE literals?

Also, in many systems, the 16 bit value '123' would equal the 32 bit
values '123'. Does this hold in conditional ACEs?

And the sign byte -- what is that for? Does -1 with a negative sign not
equal -1 with a 'none' sign? and can -1 have a positive sign?

Is the base just used for determining how the number is rendered when
converted into SDDL?

cheers,
Douglas
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