[PATCH 1/2] nfsd: return NFS4ERR_SERVERFAULT from PUTROOTFH when path in /etc/exports not found

[Benny Halevy]

On Jan. 20, 2008, 22:30 +0200, "J. Bruce Fields" <bfields at fieldses.org> wrote:
> On Sun, Jan 20, 2008 at 06:23:52PM +0200, Benny Halevy wrote:
>> Currently, when /etc/exports refers to a non-existing path, e.g.:
>> /foo     *(fsid=0,rw,sync,no_subtree_check,no_root_squash,insecure)
>>
>> nfsd4_putrootfh returns NFS4ERR_PERM which is not a valid nfsv4 error return
>> for PUTROOTFH (nor in nfsv4.1).
>>
>> NFSv4 allows the following errors for PUTROOTFH:
>>       NFS4ERR_RESOURCE
>>       NFS4ERR_SERVERFAULT
>>       NFS4ERR_WRONGSEC
>> amongst which, NFS4ERR_SERVERFAULT seems to make the most sense in this case.
> 
> If the most helpful error to return on the client side is actually
> ENOENT, then returning NFS4ERR_SERVERFAULT and depending on the client
> to map that to ENOENT seems a roundabout way to do it.  Just returning
> NFS4ERR_ENOENT would seem more in the spirit of interoperability even if
> it violates the letter of the spec.

The problem I see with that is that indeed the server went mad :-)
Since there's no path in PUTROOTFH the server is supposed to always
be able to return the filehandle for the pseudo-root fs.
the translation later on to ENOENT is just to make the application
(mount in this case) feel warm and fuzzy.

> 
> But perhaps there's also more we should do in mountd or exportfs to
> avoid this situation in the first place.

Good point, maybe deny any access, even before PUTROOTFH, if the 
exported root is inaccessible.

At any rate, returning nfserr_perm as we do today is both violating
the spec and not really identifying the root problem.

Benny

> 
> --b.
> 
>> Signed-off-by: Benny Halevy <bhalevy at panasas.com>
>> ---
>>  fs/nfsd/export.c |    4 +---
>>  1 files changed, 1 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
>> index 66d0aeb..b8b8818 100644
>> --- a/fs/nfsd/export.c
>> +++ b/fs/nfsd/export.c
>> @@ -1357,10 +1357,8 @@ exp_pseudoroot(struct svc_rqst *rqstp, struct svc_fh *fhp)
>>  	mk_fsid(FSID_NUM, fsidv, 0, 0, 0, NULL);
>>  
>>  	exp = rqst_exp_find(rqstp, FSID_NUM, fsidv);
>> -	if (PTR_ERR(exp) == -ENOENT)
>> -		return nfserr_perm;
>>  	if (IS_ERR(exp))
>> -		return nfserrno(PTR_ERR(exp));
>> +		return nfserr_serverfault;
>>  	rv = fh_compose(fhp, exp, exp->ex_dentry, NULL);
>>  	if (rv)
>>  		goto out;
>> -- 
>> 1.5.3.3
>>


-- 
Benny Halevy
Software Architect
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