Re: [PATCH] Basic support for checking NFSv4 ACLs in Linux

From: Ondrej Valousek <ondrej.valousek.xm@renesas.com>
To: Bruno Haible <bruno@clisp.org>,
	"bug-gnulib@gnu.org" <bug-gnulib@gnu.org>
Subject: Re: [PATCH] Basic support for checking NFSv4 ACLs in Linux
Date: Fri, 28 Oct 2022 14:33:15 +0000	[thread overview]
Message-ID: <TYXPR01MB18542D6569B07BD6FE8B00F0D9329@TYXPR01MB1854.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <3549181.dhzUhtFnW9@nimes>

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Hi Bruno,
1. Yes, file_has_acl() function need to be able to detect ACLs on a NFSv4 mounted volume.
Such a volume has ACLs in special format which is quite different from Posix ACLs which we only handle today.
Note that nfsv4 is standard today I.e. if you mount remote volume today on Linux via "mount server:/volume ", it will most likely will be a NFSv4 mount where gnulib can't detect acls.
2. The 'acl' package (as of today) only supports Posix ACLs and not the NFSv4 style. And besides, we do not use it anyway on modern Linux distros - see the code, instead of calling acl library, we just call getxattr() function directly.

Does it help you to understand it now?
Thanks
Ondrej

Získat Outlook pro Android<https://aka.ms/AAb9ysg>
________________________________
From: Bruno Haible <bruno@clisp.org>
Sent: Thursday, October 27, 2022 9:52:32 PM
To: bug-gnulib@gnu.org <bug-gnulib@gnu.org>
Cc: Ondrej Valousek <ondrej.valousek.xm@renesas.com>
Subject: Re: [PATCH] Basic support for checking NFSv4 ACLs in Linux

Hi Ondrej,

Thanks for the proposed patch.

But before we go into details, I would like to understand the big picture:

  1) What is the scenario in which the patch should make a difference?
     An NFSv4 volume exported from a different machine, and mounted on Linux,
     right?
     Which OSes are supported for the exporting machine?
     Which configurations need to be applied on the exporting machine?
     Which mount options need to be used on the Linux machine?

  2) When I look at the acl-2.3.1 source code [1], I get the impression that
     the Linux kernel exports the ACL attributes also for NFS. Is this true?
     To which extend does the 'acl' package support NFSv4 ACLs? To which
     extent do the maintainers of this package plan to do so?

Bruno

[1] https://jpn01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.savannah.nongnu.org%2Fcgit%2Facl.git%2F&amp;data=05%7C01%7Condrej.valousek.xm%40renesas.com%7Cbac072d29fdd4b1bb46808dab854cc82%7C53d82571da1947e49cb4625a166a4a2a%7C0%7C0%7C638024971616993649%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=tsoTFYvHtXRm2%2FqD76hpwewYpjFD73x2QwOS9iNa8lw%3D&amp;reserved=0

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