Re: [PATCH 1/1] nfsd(v2/v3): fix the failure of creation from HPUX client

["J. Bruce Fields" <bfields@fieldses.org>]

On Sun, Jan 04, 2009 at 09:53:12AM +0800, wengang wang wrote:
> Hi,
> Finally, how about this patch?
> for this problem, the solution is either to fix HPUX or to fix linux.
> are we going to fix linux?
>
> any comment is appreciated.

On my list, sorry, I just haven't gotten to it--bug me again if I
haven't dealt with it by the end of the week.--b.

>
> thanks,
> wengang.
>
> wengang wang wrote:
>> please ignore the email sent from wwg@oracle.com and reply to this post
>> if you will.
>> thanks.
>>
>> sometimes HPUX nfs client sends a create request to linux nfs server(v2/v3).
>> the dump of the request is like:
>>     obj_attributes
>>         mode: value follows
>>             set_it: value follows (1)
>>             mode: 00
>>         uid: no value
>>             set_it: no value (0)
>>         gid: value follows
>>             set_it: value follows (1)
>>             gid: 8030
>>         size: value follows
>>             set_it: value follows (1)
>>             size: 0
>>         atime: don't change
>>             set_it: don't change (0)
>>         mtime: don't change
>>             set_it: don't change (0)
>>
>> note that mode is 00(havs no rwx privilege even for the owner) and it requires
>> to set size to 0.
>>
>> as current nfsd(v2/v3) implementation, the server does mainly 2 steps:
>> 1) creates the file in mode specified by calling vfs_create().
>> 2) sets attributes for the file by calling nfsd_setattr().
>>
>> at step 2), it finally calls file system specific setattr() function which may
>> fails when checking permission because changing size needs WRITE privilege but
>> it has no since mode is 000.
>>
>> for this case, a new file created, we may simply ignore the request of setting
>> size to 0. so that the WRITE privilege is not needed and finally success.
>>
>> the patch is based on 2.6.27.10.
>>
>> Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
>> --
>>  vfs.c |   20 ++++++++++++++++++++
>>  1 file changed, 20 insertions(+)
>> diff -up ./fs/nfsd/vfs.c.orig ./fs/nfsd/vfs.c
>> --- ./fs/nfsd/vfs.c.orig	2008-12-23 14:11:14.000000000 +0800
>> +++ ./fs/nfsd/vfs.c	2008-12-23 14:54:16.000000000 +0800
>> @@ -1268,6 +1268,16 @@ nfsd_create(struct svc_rqst *rqstp, stru
>>  	switch (type) {
>>  	case S_IFREG:
>>  		host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
>> +		/* HPUX client sometimes creates a file in mode 000, and set
>> +		 * size to 0. setting size to 0 may fail for some spcific +		 * file 
>> systems by the permission checking which requires
>> +		 * WRITE privilege but the mode is 000.
>> +		 * we ignore setting size to 0 for the creation, since it's
>> +		 * just 0 after created.
>> +		 * */
>> +		if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
>> +			iap->ia_valid &= ~ATTR_SIZE;
>> +
>>  		break;
>>  	case S_IFDIR:
>>  		host_err = vfs_mkdir(dirp, dchild, iap->ia_mode);
>> @@ -1421,6 +1431,16 @@ nfsd_create_v3(struct svc_rqst *rqstp, s
>>  		/* setattr will sync the child (or not) */
>>  	}
>>  +	/* HPUX client sometimes creates a file in mode 000, and set size to 
>> 0.
>> +	 * setting size to 0 may fail for some spcific file systems by the
>> +	 * permission checking which requires WRITE privilege but the mode is
>> +	 * 000.
>> +	 * we ignore setting size to 0 for the creation, since it's just 0
>> +	 * after created.
>> +	 * */
>> +	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
>> +		iap->ia_valid &= ~ATTR_SIZE;
>> +
>>  	if (createmode == NFS3_CREATE_EXCLUSIVE) {
>>  		/* Cram the verifier into atime/mtime */
>>  		iap->ia_valid = ATTR_MTIME|ATTR_ATIME
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>   
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html