nfsd: return RESOURCE not GARBAGE_ARGS on too many ops

A client that sends more than a hundred ops in a single compound
currently gets an rpc-level GARBAGE_ARGS error.

It would be more helpful to return NFS4ERR_RESOURCE, since that gives
the client a better idea how to recover (for example by splitting up the
compound into smaller compounds).

This is all a bit academic since we've never actually seen a reason for
clients to send such long compounds, but we may as well fix it.

While we're there, just use NFSD4_MAX_OPS_PER_COMPOUND == 16, the
constant we already use in the 4.1 case, instead of hard-coding 100.
Chances anyone actually uses even 16 ops per compound are small enough
that I think there's a neglible risk or any regression.

This fixes pynfs test COMP6.

Reported-by: "Lu, Xinyu" <luxy.fnst@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index effeeb4..a0bed2b 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1703,6 +1703,9 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
        status = nfserr_minor_vers_mismatch;
        if (nfsd_minorversion(args->minorversion, NFSD_TEST) <= 0)
                goto out;
+       status = nfserr_resource;
+       if (args->opcnt > NFSD_MAX_OPS_PER_COMPOUND)
+               goto out;
 
        status = nfs41_check_op_ordering(args);
        if (status) {

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 2c61c6b..5dcd7cb 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1918,8 +1918,13 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 
        if (argp->taglen > NFSD4_MAX_TAGLEN)
                goto xdr_error;
-       if (argp->opcnt > 100)
-               goto xdr_error;
+       /*
+        * NFS4ERR_RESOURCE is a more helpful error than GARBAGE_ARGS
+        * here, so we return success at the xdr level so that
+        * nfsd4_proc can handle this is an NFS-level error.
+        */
+       if (argp->opcnt > NFSD_MAX_OPS_PER_COMPOUND)
+               return 0;
 
        if (argp->opcnt > ARRAY_SIZE(argp->iops)) {
                argp->ops = kzalloc(argp->opcnt * sizeof(*argp->ops), GFP_KERNEL);