NetBSD Problem Report #57246

From mark@ecs.vuw.ac.nz  Sun Feb 26 22:59:56 2023
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Date: Mon, 27 Feb 2023 11:59:49 +1300 (NZDT)
From: mark@ecs.vuw.ac.nz
Reply-To: mark@ecs.vuw.ac.nz
To: gnats-bugs@NetBSD.org
Subject: NFS group permissions regression
X-Send-Pr-Version: 3.95

>Number:         57246
>Category:       kern
>Synopsis:       NFS group permissions regression
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    hannken
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 26 23:00:00 +0000 2023
>Closed-Date:    Tue Mar 07 08:45:35 +0000 2023
>Last-Modified:  Tue Mar 07 08:45:35 +0000 2023
>Originator:     Mark Davies
>Release:        NetBSD 10.0_BETA
>Organization:
ECS, Victoria Uni. of Wellington, New Zealand.
>Environment:


System: NetBSD turakirae.ecs.vuw.ac.nz 10.0_BETA NetBSD 10.0_BETA (GENERIC) #1: Thu Jan 26 11:09:32 NZDT 2023 mark@turakirae.ecs.vuw.ac.nz:/local/SAVE/10_64.obj/src/work/10/src/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
        On a linux system, mounting from a NetBSD 10.0_BETA, files that should be writeable
 	over NFS due to group permissions fail, and
	lose their current contents.

>How-To-Repeat:

	On a linux system, mounting from a NetBSD 10.0_BETA
	In an NFS mounted file system, create two files - one owned by you, the other
	owned by someone else but with group permissions giving you write access.  Try
	copying first file to second.  Get error and the second file is zeroed.

	city-art% df -h .
	Filesystem               Size  Used Avail Use% Mounted on
	lido:/am/lido/home/mark  2.0T  1.1T  813G  58% /home/mark
	city-art% groups mark
	root src docker msor programmers tech ecs
	city-art% ls -la
	total 40
	drwxr-xr-x   2 mark ecs   512 Feb 27 09:40 .
	drwxr-x--x 324 mark ecs 27136 Feb 27 11:32 ..
	-rw-rw-r--   1 mark ecs     6 Feb 27 09:40 A
	-rw-rw-r--   1 www  ecs     8 Feb 27 09:40 B
	city-art% cp A B
	cp: cannot create regular file 'B': Permission denied
	city-art% ls -la
	total 36
	drwxr-xr-x   2 mark ecs   512 Feb 27 09:40 .
	drwxr-x--x 324 mark ecs 27136 Feb 27 11:32 ..
	-rw-rw-r--   1 mark ecs     6 Feb 27 09:40 A
	-rw-rw-r--   1 www  ecs     0 Feb 27 09:42 B


	Doing this from NetBSD to NetBSD works
	Doing this from linux to NetBSD 9.3_STABLE works


>Fix:
	No idea, would love one


>Release-Note:

>Audit-Trail:
From: "J. Hannken-Illjes" <hannken@mailbox.org>
To: NetBSD GNATS <gnats-bugs@netbsd.org>
Cc: 
Subject: Re: kern/57246: NFS group permissions regression
Date: Tue, 28 Feb 2023 15:36:30 +0100

 This failure can be reduced to:

 - Create a file xxx in a ffs file system, mode -rw-rw-r-- and
   make sure you are not the owner but the group member.

 - Try to touch this file (touch xxx) and get "Permission denied".

 Operation ufs_setattr() runs genfs_can_chtimes() ->
   VOP_ACCESSX( VWRITE_ATTRIBUTES ) ->
   ufs_accessx() ->
   vfs_unixify_accmode(&accmode),
 this translates VWRITE_ATTRIBUTES into VADMIN and the access
 check fails as we are not the owner.

 vfs_unixify_accmode() definitely needs work ...

 --
 J. Hannken-Illjes - hannken@mailbox.org

From: mlelstv@serpens.de (Michael van Elst)
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/57246: NFS group permissions regression
Date: Tue, 28 Feb 2023 15:59:05 -0000 (UTC)

 hannken@mailbox.org ("J. Hannken-Illjes") writes:

 >The following reply was made to PR kern/57246; it has been noted by GNATS.

 >From: "J. Hannken-Illjes" <hannken@mailbox.org>
 >To: NetBSD GNATS <gnats-bugs@netbsd.org>
 >Cc: 
 >Subject: Re: kern/57246: NFS group permissions regression
 >Date: Tue, 28 Feb 2023 15:36:30 +0100

 > This failure can be reduced to:
 > 
 > - Create a file xxx in a ffs file system, mode -rw-rw-r-- and
 >   make sure you are not the owner but the group member.
 > 
 > - Try to touch this file (touch xxx) and get "Permission denied".
 > 
 > Operation ufs_setattr() runs genfs_can_chtimes() ->
 >   VOP_ACCESSX( VWRITE_ATTRIBUTES ) ->
 >   ufs_accessx() ->
 >   vfs_unixify_accmode(&accmode),
 > this translates VWRITE_ATTRIBUTES into VADMIN and the access
 > check fails as we are not the owner.
 > 
 > vfs_unixify_accmode() definitely needs work ...


 According to utimes(2) that's even correct. Only futimes() / futimens()
 allow setting the time by someone who is neither owner nor super-user (but
 has write permission) and touch should then call open() + futimens().

From: "Juergen Hannken-Illjes" <hannken@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/57246 CVS commit: src/sys/miscfs/genfs
Date: Fri, 3 Mar 2023 10:02:51 +0000

 Module Name:	src
 Committed By:	hannken
 Date:		Fri Mar  3 10:02:51 UTC 2023

 Modified Files:
 	src/sys/miscfs/genfs: genfs_vnops.c

 Log Message:
 Fix genfs_can_chtimes() to also handle the condition:

   If the time pointer is null, then write permission
   on the file is also sufficient.

 From FreeBSD.

 Should fix PR kern/57246 "NFS group permissions regression"


 To generate a diff of this commit:
 cvs rdiff -u -r1.219 -r1.220 src/sys/miscfs/genfs/genfs_vnops.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: Mark Davies <mark@ecs.vuw.ac.nz>
To: gnats-bugs@netbsd.org, kern-bug-people@netbsd.org, gnats-admin@netbsd.org,
        netbsd-bugs@netbsd.org
Cc: 
Subject: Re: PR/57246 CVS commit: src/sys/miscfs/genfs
Date: Sun, 5 Mar 2023 13:44:04 +1300

 On 3/03/23 23:05, Juergen Hannken-Illjes wrote:
 >   Modified Files:
 >   	src/sys/miscfs/genfs: genfs_vnops.c
 >   
 >   Log Message:
 >   Fix genfs_can_chtimes() to also handle the condition:
 >   
 >     If the time pointer is null, then write permission
 >     on the file is also sufficient.
 >   
 >   From FreeBSD.
 >   
 >   Should fix PR kern/57246 "NFS group permissions regression"


 Seem to fix the touching the file on the local machine issue that 
 Juergen noted, but not copying files over NFS from linux - that still fails.

 cheers
 mark

From: Mark Davies <mark@ecs.vuw.ac.nz>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/57246: NFS group permissions regression
Date: Sun, 5 Mar 2023 13:49:54 +1300

 Note that
 https://mail-index.netbsd.org/tech-kern/2023/02/28/msg028743.html

 has tcpdump traces of the issue.

From: "J. Hannken-Illjes" <hannken@mailbox.org>
To: NetBSD GNATS <gnats-bugs@netbsd.org>
Cc: 
Subject: Re: PR/57246 CVS commit: src/sys/miscfs/genfs
Date: Sun, 5 Mar 2023 11:14:36 +0100

 --Apple-Mail=_B3D2EC19-0C54-4670-8962-899E5B1A4E61
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 Content-Type: text/plain;
 	charset=us-ascii

 Expanding the SETATTR call from linux-netbsd10.tcpdump gives:

 Network File System, SETATTR Call FH: 0xf9f94117
     [Program Version: 3]
     [V3 Procedure: SETATTR (2)]
     object
         length: 28
         [hash (CRC-32): 0xf9f94117]
         FileHandle: 06a800008b07000010000000aa26842502cd6f050000000000000000
     new_attributes
         mode: no value
             set_it: no value (0)
         uid: no value
             set_it: no value (0)
         gid: no value
             set_it: no value (0)
         size: value follows
             set_it: value follows (1)
             size: 0
         atime: don't change
             set_it: don't change (0)
         mtime: set to server time
             set_it: set to server time (1)
     guard: no value
         check: no value (0)

 It has "mtime: set to server time" which is exactly the
 test I fixed in NetBSD-current.

 I tried it here with RHEL8 as Linux and NetBSD-current, get
 the same SETATTR call and it fails before my patch and
 succeeds after it.

 Are you really sure your NetBSD kernel has this change
 (genfs_vnops.c rev. 1.220)?  The NetBSD-10 tree is not
 updated yet, ticket #111 is waiting.

 --
 J. Hannken-Illjes - hannken@mailbox.org

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From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/57246 CVS commit: [netbsd-10] src/sys/miscfs/genfs
Date: Sun, 5 Mar 2023 14:34:59 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Sun Mar  5 14:34:59 UTC 2023

 Modified Files:
 	src/sys/miscfs/genfs [netbsd-10]: genfs_vnops.c

 Log Message:
 Pull up following revision(s) (requested by hannken in ticket #111):

 	sys/miscfs/genfs/genfs_vnops.c: revision 1.220

 Fix genfs_can_chtimes() to also handle the condition:

   If the time pointer is null, then write permission
   on the file is also sufficient.

 From FreeBSD.

 Should fix PR kern/57246 "NFS group permissions regression"


 To generate a diff of this commit:
 cvs rdiff -u -r1.219 -r1.219.4.1 src/sys/miscfs/genfs/genfs_vnops.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: Mark Davies <mark@ecs.vuw.ac.nz>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: PR/57246 CVS commit: src/sys/miscfs/genfs
Date: Mon, 6 Mar 2023 12:50:44 +1300

 On 5/03/23 23:15, J. Hannken-Illjes wrote:
 >   Are you really sure your NetBSD kernel has this change
 >   (genfs_vnops.c rev. 1.220)?  The NetBSD-10 tree is not
 >   updated yet, ticket #111 is waiting.

 Odd.  So I updated my 10_BETA tree to yesterday, then applied your 1.220
 to it, rebuild and installed that on a test system. Reproduced the test 
 setup and tried it and the cp still failed.  Pretty sure that the patch 
 is in place as the "touch" on the local filesystem now works where it 
 didn't before.

 cheers
 mark

From: Mark Davies <mark@ecs.vuw.ac.nz>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: PR/57246 CVS commit: src/sys/miscfs/genfs
Date: Tue, 7 Mar 2023 13:02:58 +1300

 On 6/03/23 12:55, Mark Davies wrote:
 >   Odd.  So I updated my 10_BETA tree to yesterday, then applied your 1.220
 >   to it, rebuild and installed that on a test system. Reproduced the test
 >   setup and tried it and the cp still failed.  Pretty sure that the patch
 >   is in place as the "touch" on the local filesystem now works where it
 >   didn't before.


 Turns out linux was caching the failure result from the setattr so 
 wasn't actually even trying to do it on the updated system.

 If I test with a pair of files that it hadn't previously cached, or 
 touch the original files so that linux thinks they have changed then it 
 works.

 So its all good and this ticket can be closed.

 cheers
 mark

Responsible-Changed-From-To: kern-bug-people->hannken
Responsible-Changed-By: hannken@NetBSD.org
Responsible-Changed-When: Tue, 07 Mar 2023 08:45:35 +0000
Responsible-Changed-Why:
Take, committed a fix.


State-Changed-From-To: open->closed
State-Changed-By: hannken@NetBSD.org
State-Changed-When: Tue, 07 Mar 2023 08:45:35 +0000
State-Changed-Why:
Fix committed and pulled up.


>Unformatted:

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