nfsd: decode implementation id

Decode the implementation ID and display in nfsd/clients/#/info.  It may
be help identify the client.  It won't be used otherwise.

(When this went into the protocol, I thought the implementation ID would
be a slippery slope towards implementation-specific workarounds as with
the http user-agent.  But I guess I was wrong, the risk seems pretty low
now.)
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -1899,6 +1899,8 @@ static void __free_client(struct kref *k)
 	free_svc_cred(&clp->cl_cred);
 	kfree(clp->cl_ownerstr_hashtbl);
 	kfree(clp->cl_name.data);
+	kfree(clp->cl_nii_domain.data);
+	kfree(clp->cl_nii_name.data);
 	idr_destroy(&clp->cl_stateids);
 	kmem_cache_free(client_slab, clp);
 }
@@ -2261,6 +2263,15 @@ static int client_info_show(struct seq_file *m, void *v)
 	seq_printf(m, "name: ");
 	seq_quote_mem(m, clp->cl_name.data, clp->cl_name.len);
 	seq_printf(m, "\nminor version: %d\n", clp->cl_minorversion);
+	if (clp->cl_nii_domain.data) {
+		seq_printf(m, "Implementation domain: ");
+		seq_quote_mem(m, clp->cl_nii_domain.data,
+					clp->cl_nii_domain.len);
+		seq_printf(m, "\nImplementation name: ");
+		seq_quote_mem(m, clp->cl_nii_name.data, clp->cl_nii_name.len);
+		seq_printf(m, "\nImplementation time: [%ld, %ld]\n",
+			clp->cl_nii_time.tv_sec, clp->cl_nii_time.tv_nsec);
+	}
 	drop_client(clp);
 
 	return 0;
@@ -2901,6 +2912,22 @@ static bool client_has_state(struct nfs4_client *clp)
 		|| !list_empty(&clp->async_copies);
 }
 
+static __be32 copy_impl_id(struct nfs4_client *clp,
+				struct nfsd4_exchange_id *exid)
+{
+	if (!exid->nii_domain.data)
+		return 0;
+	xdr_netobj_dup(&clp->cl_nii_domain, &exid->nii_domain, GFP_KERNEL);
+	if (!clp->cl_nii_domain.data)
+		return nfserr_jukebox;
+	xdr_netobj_dup(&clp->cl_nii_name, &exid->nii_name, GFP_KERNEL);
+	if (!clp->cl_nii_name.data)
+		return nfserr_jukebox;
+	clp->cl_nii_time.tv_sec = exid->nii_time.tv_sec;
+	clp->cl_nii_time.tv_nsec = exid->nii_time.tv_nsec;
+	return 0;
+}
+
 __be32
 nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		union nfsd4_op_u *u)
@@ -2927,6 +2954,9 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	new = create_client(exid->clname, rqstp, &verf);
 	if (new == NULL)
 		return nfserr_jukebox;
+	status = copy_impl_id(new, exid);
+	if (status)
+		goto out_nolock;
 
 	switch (exid->spa_how) {
 	case SP4_MACH_CRED:

fs/nfsd/nfs4xdr.c

@@ -1389,7 +1389,6 @@ nfsd4_decode_exchange_id(struct nfsd4_compoundargs *argp,
 		goto xdr_error;
 	}
 
-	/* Ignore Implementation ID */
 	READ_BUF(4);    /* nfs_impl_id4 array length */
 	dummy = be32_to_cpup(p++);
 
@@ -1397,21 +1396,19 @@ nfsd4_decode_exchange_id(struct nfsd4_compoundargs *argp,
 		goto xdr_error;
 
 	if (dummy == 1) {
-		/* nii_domain */
-		READ_BUF(4);
-		dummy = be32_to_cpup(p++);
-		READ_BUF(dummy);
-		p += XDR_QUADLEN(dummy);
+		status = nfsd4_decode_opaque(argp, &exid->nii_domain);
+		if (status)
+			goto xdr_error;
 
 		/* nii_name */
-		READ_BUF(4);
-		dummy = be32_to_cpup(p++);
-		READ_BUF(dummy);
-		p += XDR_QUADLEN(dummy);
+		status = nfsd4_decode_opaque(argp, &exid->nii_name);
+		if (status)
+			goto xdr_error;
 
 		/* nii_date */
-		READ_BUF(12);
-		p += 3;
+		status = nfsd4_decode_time(argp, &exid->nii_time);
+		if (status)
+			goto xdr_error;
 	}
 	DECODE_TAIL;
 }

fs/nfsd/state.h

@@ -317,6 +317,10 @@ struct nfs4_client {
 	clientid_t		cl_clientid;	/* generated by server */
 	nfs4_verifier		cl_confirm;	/* generated by server */
 	u32			cl_minorversion;
+	/* NFSv4.1 client implementation id: */
+	struct xdr_netobj	cl_nii_domain;
+	struct xdr_netobj	cl_nii_name;
+	struct timespec		cl_nii_time;
 
 	/* for v4.0 and v4.1 callbacks: */
 	struct nfs4_cb_conn	cl_cb_conn;

fs/nfsd/xdr4.h

@@ -410,6 +410,9 @@ struct nfsd4_exchange_id {
 	int		spa_how;
 	u32             spo_must_enforce[3];
 	u32             spo_must_allow[3];
+	struct xdr_netobj nii_domain;
+	struct xdr_netobj nii_name;
+	struct timespec64 nii_time;
 };
 
 struct nfsd4_sequence {