Re: [PATCH] overlayfs: ignore empty NFSv4 ACLs in ext4 upperdir

Patrick Plagwitz
2016-12-05T18:25:48Z

On 12/05/2016 05:25 PM, J. Bruce Fields wrote:
> On Mon, Dec 05, 2016 at 04:36:03PM +0100, Miklos Szeredi wrote:
>> On Mon, Dec 5, 2016 at 4:19 PM, J. Bruce Fields <bfields@fieldses.org> wrote:
>>>> Can NFS people comment on this? Where does the nfs4_acl come from?
>>>
>>> This is the interface the NFS client provides for applications to modify
>>> NFSv4 ACLs on servers that support them.
>>
>> Fine, but why are we seeing this xattr on exports where no xattrs are
>> set on the exported fs?
>
> I don't know. I took another look at the original patch and don't see
> any details on the server setup: which server is it (knfsd, ganesha,
> netapp, ...)? How is it configured?
>
The server is the one in the kernel (knfsd, I assume), with completely default
configuration. /etc/exports is

/srv/nfsv4 localhost(fsid=root)

Adding rw, or various other options, does not change the observations in the
original mail. As far as I know, there are no options for controlling ACLs.

>>>> What can overlayfs do if it's a non-empty ACL?
>>>
>>> As little as possible. You can't copy it up, can you? So any attempt
>>> to support it is going to be incomplete.
>>
>> Right.
>>
>>>
>>>> Does knfsd translate posix ACL into NFS acl? If so, we can translate
>>>> back. Should we do a generic POSIX<->NFS acl translator?
>>>
>>> knsd does translate between POSIX and NFSv4 ACLs. It's a complicated
>>
>> This does explain the nfs4_acl xattr on the client. Question: if it's
>> empty, why have it at all?
>
> I'm honestly not sure what's going on there. I'd be curious to see a
> network trace if possible.
>
Just make folders like in the original mail, start the NFS server with the
exports from above and touch merged/folder/file to reproduce the problem.
I don't know anything about the NFS protocol but here you have a tshark
packet summary as well as the details from the folder/ lookup reply (51).
As far as I can tell, no ACL information is in there.

22 NFS 286 V4 Call CREATE_SESSION
23 NFS 214 V4 Reply (Call In 22) CREATE_SESSION
24 NFS 214 V4 Call RECLAIM_COMPLETE
26 NFS 178 V4 Reply (Call In 24) RECLAIM_COMPLETE
27 NFS 218 V4 Call SECINFO_NO_NAME
29 NFS 194 V4 Reply (Call In 27) SECINFO_NO_NAME
30 NFS 230 V4 Call PUTROOTFH | GETATTR
31 NFS 350 V4 Reply (Call In 30) PUTROOTFH | GETATTR
32 NFS 242 V4 Call GETATTR FH: 0x62d40c52
33 NFS 254 V4 Reply (Call In 32) GETATTR
34 NFS 242 V4 Call GETATTR FH: 0x62d40c52
35 NFS 254 V4 Reply (Call In 34) GETATTR
36 NFS 242 V4 Call GETATTR FH: 0x62d40c52
37 NFS 254 V4 Reply (Call In 36) GETATTR
38 NFS 242 V4 Call GETATTR FH: 0x62d40c52
39 NFS 254 V4 Reply (Call In 38) GETATTR
40 NFS 234 V4 Call GETATTR FH: 0x62d40c52
41 NFS 206 V4 Reply (Call In 40) GETATTR
42 NFS 242 V4 Call GETATTR FH: 0x62d40c52
43 NFS 254 V4 Reply (Call In 42) GETATTR
44 NFS 238 V4 Call GETATTR FH: 0x62d40c52
45 NFS 330 V4 Reply (Call In 44) GETATTR
46 NFS 246 V4 Call ACCESS FH: 0x62d40c52, [Check: RD LU MD XT DL]
47 NFS 258 V4 Reply (Call In 46) ACCESS, [Access Denied: MD XT DL], [Allowed: RD LU]
48 NFS 238 V4 Call GETATTR FH: 0x62d40c52
49 NFS 250 V4 Reply (Call In 48) GETATTR
50 NFS 258 V4 Call LOOKUP DH: 0x62d40c52/folder
51 NFS 366 V4 Reply (Call In 50) LOOKUP
52 NFS 254 V4 Call ACCESS FH: 0x96d0c04a, [Check: RD LU MD XT DL]
53 NFS 258 V4 Reply (Call In 52) ACCESS, [Access Denied: MD XT DL], [Allowed: RD LU]
54 NFS 262 V4 Call LOOKUP DH: 0x96d0c04a/file
55 NFS 186 V4 Reply (Call In 54) LOOKUP Status: NFS4ERR_NOENT
56 NFS 246 V4 Call GETATTR FH: 0x96d0c04a
57 NFS 278 V4 Reply (Call In 56) GETATTR

Network File System, Ops(5): SEQUENCE PUTFH LOOKUP GETFH GETATTR
[Program Version: 4]
[V4 Procedure: COMPOUND (1)]
Status: NFS4_OK (0)
Tag: <EMPTY>
length: 0
contents: <EMPTY>
Operations (count: 5)
Opcode: SEQUENCE (53)
Status: NFS4_OK (0)
sessionid: 50a245584a819c9a0a00000000000000
seqid: 0x0000000d
slot id: 0
high slot id: 30
target high slot id: 30
status flags: 0x00000000
.... .... .... .... .... .... .... ...0 = SEQ4_STATUS_CB_PATH_DOWN: Not set
.... .... .... .... .... .... .... ..0. = SEQ4_STATUS_CB_GSS_CONTEXTS_EXPIRING: Not set
.... .... .... .... .... .... .... .0.. = SEQ4_STATUS_CB_GSS_CONTEXTS_EXPIRED: Not set
.... .... .... .... .... .... .... 0... = SEQ4_STATUS_EXPIRED_ALL_STATE_REVOKED: Not set
.... .... .... .... .... .... ...0 .... = SEQ4_STATUS_EXPIRED_SOME_STATE_REVOKED: Not set
.... .... .... .... .... .... ..0. .... = SEQ4_STATUS_ADMIN_STATE_REVOKED: Not set
.... .... .... .... .... .... .0.. .... = SEQ4_STATUS_RECALLABLE_STATE_REVOKED: Not set
.... .... .... .... .... .... 0... .... = SEQ4_STATUS_LEASE_MOVED: Not set
.... .... .... .... .... ...0 .... .... = SEQ4_STATUS_RESTART_RECLAIM_NEEDED: Not set
.... .... .... .... .... ..0. .... .... = SEQ4_STATUS_CB_PATH_DOWN_SESSION: Not set
.... .... .... .... .... .0.. .... .... = SEQ4_STATUS_BACKCHANNEL_FAULT: Not set
.... .... .... .... .... 0... .... .... = SEQ4_STATUS_DEVID_CHANGED: Not set
.... .... .... .... ...0 .... .... .... = SEQ4_STATUS_DEVID_DELETED: Not set
Opcode: PUTFH (22)
Status: NFS4_OK (0)
Opcode: LOOKUP (15)
Status: NFS4_OK (0)
Opcode: GETFH (10)
Status: NFS4_OK (0)
Filehandle
length: 16
[hash (CRC-32): 0x96d0c04a]
filehandle: 0100010100000000790f04000762a435
Opcode: GETATTR (9)
Status: NFS4_OK (0)
Attr mask[0]: 0x0010011a (Type, Change, Size, FSID, FileId)
reqd_attr: Type (1)
ftype4: NF4DIR (2)
reqd_attr: Change (3)
changeid: 6360241138682687914
reqd_attr: Size (4)
size: 4096
reqd_attr: FSID (8)
fattr4_fsid
fsid4.major: 0
fsid4.minor: 0
reco_attr: FileId (20)
fileid: 266105
Attr mask[1]: 0x00b0a23a (Mode, NumLinks, Owner, Owner_Group, RawDev, Space_Used, Time_Access, Time_Metadata, Time_Modify, Mounted_on_FileId)
reco_attr: Mode (33)
mode: 0755, Name: Unknown, Read permission for owner, Write permission for owner, Execute permission for owner, Read permission for group, Execute
permission for group, Read permission for others, Execute permission for others
.... .... .... .... 000. .... .... .... = Name: Unknown (0)
.... .... .... .... .... 0... .... .... = Set user id on exec: No
.... .... .... .... .... .0.. .... .... = Set group id on exec: No
.... .... .... .... .... ..0. .... .... = Save swapped text even after use: No
.... .... .... .... .... ...1 .... .... = Read permission for owner: Yes
.... .... .... .... .... .... 1... .... = Write permission for owner: Yes
.... .... .... .... .... .... .1.. .... = Execute permission for owner: Yes
.... .... .... .... .... .... ..1. .... = Read permission for group: Yes
.... .... .... .... .... .... ...0 .... = Write permission for group: No
.... .... .... .... .... .... .... 1... = Execute permission for group: Yes
.... .... .... .... .... .... .... .1.. = Read permission for others: Yes
.... .... .... .... .... .... .... ..0. = Write permission for others: No
.... .... .... .... .... .... .... ...1 = Execute permission for others: Yes
reco_attr: NumLinks (35)
numlinks: 2
reco_attr: Owner (36)
fattr4_owner: 0
length: 1
contents: 0
fill bytes: opaque data
reco_attr: Owner_Group (37)
fattr4_owner_group: 0
length: 1
contents: 0
fill bytes: opaque data
reco_attr: RawDev (41)
specdata1: 0
specdata2: 0
reco_attr: Space_Used (45)
space_used: 4096
reco_attr: Time_Access (47)
seconds: 1480888617
nseconds: 513333330
reco_attr: Time_Metadata (52)
seconds: 1480859038
nseconds: 486666666
reco_attr: Time_Modify (53)
seconds: 1480859038
nseconds: 486666666
reco_attr: Mounted_on_FileId (55)
fileid: 0x0000000000040f79
[Main Opcode: LOOKUP (15)]