Re: NFSv4 setattr null-terminates strings

[Dave Chiluk <dave.chiluk@canonical.com>]

On 03/08/2013 12:33 PM, Myklebust, Trond wrote:
> On Fri, 2013-03-08 at 11:11 -0600, Dave Chiluk wrote:
>> As of commit 57e62324e469e092ecc6c94a7a86fe4bd6ac5172, the SETATTR nfsv4
>> command now null terminates fattr_owner and fattr_owner_group.
>>
>> Here is an example excerpt from a tcpdump
>> Opcode: SETATTR (34)
>>     stateid
>>         [StateID Hash: 0xafa9]
>>         seqid: 0x00000000
>>         Data: 000000000000000000000000
>>     obj_attributes
>>         attrmask
>>             recc_attr: FATTR4_OWNER_GROUP (37)
>>                 fattr4_owner_group: groupname@domainname.com
>>                     length: 25
>>
>> This means that even though there are actually 24 characters in
>> groupname@domainname.com, we now send 24 characters + 1 null character.
>> Hence the total length of 25.  Previously the client would send just the
>> 24 characters and set length to 24.
>>
>> This isn't an issue for communication with other Linux machines, but it
>> is an issue for interaction with AIX machines.  As is discussed here.
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1101292
>>
>> I attempted to read the RFC available here
>> http://tools.ietf.org/html/rfc5661, but have not been able to find a
>> statement instructing one way or the other.
>>
>> So the question becomes, is it correct for linux to be sending this null
>> terminator when read against the RFC, or is it AIX's responsibility to
>> handle null-terminated strings?
> 
> The client is definitely in error here according to RFC3530. Please
> check if the attached patch fixes the issue for you.
> 
> Cheers
>   Trond
> 

Trond,

This appears to work great.  Can you give me an idea when this will get
pulled into the the linux-nfs tree and eventually the mainline tree?

Dave.