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authorChuck Lever <chuck.lever@oracle.com>2021-12-21 19:52:06 +0300
committerChuck Lever <chuck.lever@oracle.com>2022-01-08 22:42:01 +0300
commit6a2f774424bfdcc2df3e17de0cefe74a4269cad5 (patch)
tree950b7a0ff692a5cb7da12674c93d5463bc2c0407 /fs/nfsd
parent47446d74f1707049067fee038507cdffda805631 (diff)
downloadlinux-6a2f774424bfdcc2df3e17de0cefe74a4269cad5.tar.xz
NFSD: Fix zero-length NFSv3 WRITEs
The Linux NFS server currently responds to a zero-length NFSv3 WRITE request with NFS3ERR_IO. It responds to a zero-length NFSv4 WRITE with NFS4_OK and count of zero. RFC 1813 says of the WRITE procedure's @count argument: count The number of bytes of data to be written. If count is 0, the WRITE will succeed and return a count of 0, barring errors due to permissions checking. RFC 8881 has similar language for NFSv4, though NFSv4 removed the explicit @count argument because that value is already contained in the opaque payload array. The synthetic client pynfs's WRT4 and WRT15 tests do emit zero- length WRITEs to exercise this spec requirement. Commit fdec6114ee1f ("nfsd4: zero-length WRITE should succeed") addressed the same problem there with the same fix. But interestingly the Linux NFS client does not appear to emit zero- length WRITEs, instead squelching them. I'm not aware of a test that can generate such WRITEs for NFSv3, so I wrote a naive C program to generate a zero-length WRITE and test this fix. Fixes: 8154ef2776aa ("NFSD: Clean up legacy NFS WRITE argument XDR decoders") Reported-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Cc: stable@vger.kernel.org Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/nfs3proc.c6
-rw-r--r--fs/nfsd/nfsproc.c5
2 files changed, 1 insertions, 10 deletions
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 4418517f6f12..2c681785186f 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -202,15 +202,11 @@ nfsd3_proc_write(struct svc_rqst *rqstp)
fh_copy(&resp->fh, &argp->fh);
resp->committed = argp->stable;
nvecs = svc_fill_write_vector(rqstp, &argp->payload);
- if (!nvecs) {
- resp->status = nfserr_io;
- goto out;
- }
+
resp->status = nfsd_write(rqstp, &resp->fh, argp->offset,
rqstp->rq_vec, nvecs, &cnt,
resp->committed, resp->verf);
resp->count = cnt;
-out:
return rpc_success;
}
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index eea5b59b6a6c..1743ed04197e 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -235,10 +235,6 @@ nfsd_proc_write(struct svc_rqst *rqstp)
argp->len, argp->offset);
nvecs = svc_fill_write_vector(rqstp, &argp->payload);
- if (!nvecs) {
- resp->status = nfserr_io;
- goto out;
- }
resp->status = nfsd_write(rqstp, fh_copy(&resp->fh, &argp->fh),
argp->offset, rqstp->rq_vec, nvecs,
@@ -247,7 +243,6 @@ nfsd_proc_write(struct svc_rqst *rqstp)
resp->status = fh_getattr(&resp->fh, &resp->stat);
else if (resp->status == nfserr_jukebox)
return rpc_drop_reply;
-out:
return rpc_success;
}