From: Yang Hongyang Subject: Re: [PATCH] NFSD: do not return nfserr_symlink for the LINK operation Date: Fri, 20 Mar 2009 15:05:42 +0800 Message-ID: <49C34046.4060306@cn.fujitsu.com> References: <49B2C404.3060907@panasas.com> <20090309180643.GB9408@fieldses.org> <49BA15B3.2040904@cn.fujitsu.com> <20090318230621.GK18894@fieldses.org> <49C1EB55.8060700@panasas.com> <49C1ED5B.6040000@cn.fujitsu.com> <49C1EE65.7010008@panasas.com> <49C1FFC7.6070709@cn.fujitsu.com> <49C20F6F.2040704@panasas.com> <49C21485.5070306@cn.fujitsu.com> <20090319200035.GC5499@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Benny Halevy , Trond Myklebust , Ni Wenjuan , linux-nfs@vger.kernel.org To: "J. Bruce Fields" Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:64671 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752242AbZCTHGh (ORCPT ); Fri, 20 Mar 2009 03:06:37 -0400 In-Reply-To: <20090319200035.GC5499@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: J. Bruce Fields wrote: > On Thu, Mar 19, 2009 at 05:46:45PM +0800, Yang Hongyang wrote: >> v1->v2:update some code style problem >> ------------------------- >> >> There are four placees that returned inappropriate err nfserr_symlink accroding to >> newpynfs test #LINK4a#LOOKP2a#OPCF3a#SATT12a.nfserr_symlink do not listed >> in these operations's err list in the spec. >> For LINK and LOOKUPP operation,nfserr_notdir should be returned. >> For OPEN_CONFIRM and SETATTR operation,nfserr_inval should be returned. > > I thought Benny found that this also caused the linux client to return a > better error in one of these cases--could you confirm that and add a > mention of it in the commit message? > > (I'm reluctant to take patches like this based *only* on the spec > language, partly because rfc 3530 is known to have a few oversights in > the error listings.) > > I definitely appreciate people going through the pynfs tests and > investigating the results, but I don't want patch whose only > justification is that they quiet pynfs--we need to think about the > likely effect on real clients too. > > --b. > Just as Bruce said: open_confirm is done with the same filehandle that was returned from a previous OPEN. But an OPEN should never return the filehandle for a symlink. That means for us to reach this case, either the client or our filesystem has a very serious bug. Therefore, I'm not convinced that getting the error return correct in this case is worth the trouble. OPEN_CONFIRM may never hit the error return. And i did a test through following commands on a nfs4 fs: #touch test #ln -s test 1 #ln 1 2 It just creat a symlink 2 to test as on the local fs.Accroding to this,I think link op will never hit the nfserr_symlink err return either. For the reasons above,There seems to be only one op *LOOKUPP* that needs to be fixed.But still,I consider we should fix it all even the error return won't be triggered through real client use cauz there can be chances that a specially designed programme can triggered the bug. If the bug is not the return value issue but a memory overflow or some other strictness,the server may down by such attack. ------------------------------------------------------------------------------------------- There are four placees that returned inappropriate err nfserr_symlink accroding to newpynfs test #LINK4a#LOOKP2a#OPCF3a#SATT12a.nfserr_symlink do not listed in these operations's err list in the spec. Benny Halevy pointed out that the linux nfs client translates NFS4ERR_SYMLINK to -ELOOP which is awkward and less descriptive to the app/user than -ENOTDIR. So a careful client implementation should never get NFS4ERR_SYMLINK if it stats the directory it operates on before sending the link op (or lookup, create, rename, etc.) to make sure it is indeed a directory. [Sigh, looking at the code - it looks like we'll return NFS4ERR_ISDIR for a length-changing SETATTR operating on a directory. This is fine in NFSv4.0 but this error was removed for SETATTR in nfs4.1. Note to self: revise this in the nfs41 tree] Signed-off-by: Yang Hongyang Reviewed-by: Benny Halevy --- fs/nfsd/nfs4proc.c | 6 +++++- fs/nfsd/nfs4state.c | 6 +++++- fs/nfsd/vfs.c | 6 ++++++ 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index 9fa60a3..9aaecaa 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -493,8 +493,12 @@ nfsd4_lookupp(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, return nfserr_noent; } fh_put(&tmp_fh); - return nfsd_lookup(rqstp, &cstate->current_fh, + ret = nfsd_lookup(rqstp, &cstate->current_fh, "..", 2, &cstate->current_fh); + /* nfserr_symlink returned is inappropriate for LOOKUPP */ + if (ret == nfserr_symlink) + ret = nfserr_notdir; + return ret; } static __be32 diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index b6f60f4..28e4688 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2234,8 +2234,12 @@ nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, cstate->current_fh.fh_dentry->d_name.name); status = fh_verify(rqstp, &cstate->current_fh, S_IFREG, 0); - if (status) + if (status) { + /* nfserr_symlink returned is inappropriate for OPEN_CONFIRM */ + if (status == nfserr_symlink) + status = nfserr_inval; return status; + } nfs4_lock_state(); diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 6e50aaa..015a655 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -397,6 +397,9 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap, if (EX_ISSYNC(fhp->fh_export)) write_inode_now(inode, 1); out: + /* nfserr_symlink returned is inappropriate for SETATTR */ + if (err == nfserr_symlink) + err = nfserr_inval; return err; out_nfserr: @@ -1637,6 +1640,9 @@ out_dput: out_unlock: fh_unlock(ffhp); out: + /* nfserr_symlink returned is inappropriate for LINK */ + if (err == nfserr_symlink) + err = nfserr_notdir; return err; out_nfserr: -- 1.6.0.3 -- Regards Yang Hongyang