[PATCH v13 11/19] nfsd: implement server support for NFS_LOCALIO_PROGRAM

[Mike Snitzer <snitzer@kernel.org>]

The LOCALIO auxiliary RPC protocol consists of a single "UUID_IS_LOCAL"
RPC method that allows the Linux NFS client to verify the local Linux
NFS server can see the nonce (single-use UUID) the client generated and
made available in nfs_common.  This protocol isn't part of an IETF
standard, nor does it need to be considering it is Linux-to-Linux
auxiliary RPC protocol that amounts to an implementation detail.

The UUID_IS_LOCAL method encodes the client generated uuid_t in terms of
the fixed UUID_SIZE (16 bytes).  The fixed size opaque encode and decode
XDR methods are used instead of the less efficient variable sized
methods.

The RPC program number for the NFS_LOCALIO_PROGRAM is 400122 (as assigned
by IANA, see https://www.iana.org/assignments/rpc-program-numbers/ ):
Linux Kernel Organization       400122  nfslocalio

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
[neilb: factored out and simplified single localio protocol]
Co-developed-by: NeilBrown <neil@brown.name>
Signed-off-by: NeilBrown <neil@brown.name>
---
 fs/nfsd/localio.c   | 75 +++++++++++++++++++++++++++++++++++++++++++++
 fs/nfsd/nfsd.h      |  4 +++
 fs/nfsd/nfssvc.c    | 23 +++++++++++++-
 include/linux/nfs.h |  7 +++++
 4 files changed, 108 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c
index 8e0cce835f81..2ceab49f3cb6 100644
--- a/fs/nfsd/localio.c
+++ b/fs/nfsd/localio.c
@@ -13,12 +13,15 @@
 #include <linux/nfs.h>
 #include <linux/nfs_common.h>
 #include <linux/nfslocalio.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_xdr.h>
 #include <linux/string.h>
 
 #include "nfsd.h"
 #include "vfs.h"
 #include "netns.h"
 #include "filecache.h"
+#include "cache.h"
 
 /**
  * nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to @file
@@ -106,3 +109,75 @@ EXPORT_SYMBOL_GPL(nfsd_open_local_fh);
 
 /* Compile time type checking, not used by anything */
 static nfs_to_nfsd_open_local_fh_t __maybe_unused nfsd_open_local_fh_typecheck = nfsd_open_local_fh;
+
+/*
+ * UUID_IS_LOCAL XDR functions
+ */
+
+static __be32 localio_proc_null(struct svc_rqst *rqstp)
+{
+	return rpc_success;
+}
+
+struct localio_uuidarg {
+	uuid_t			uuid;
+};
+
+static __be32 localio_proc_uuid_is_local(struct svc_rqst *rqstp)
+{
+	struct localio_uuidarg *argp = rqstp->rq_argp;
+
+	(void) nfs_uuid_is_local(&argp->uuid, SVC_NET(rqstp),
+				 rqstp->rq_client);
+
+	return rpc_success;
+}
+
+static bool localio_decode_uuidarg(struct svc_rqst *rqstp,
+				   struct xdr_stream *xdr)
+{
+	struct localio_uuidarg *argp = rqstp->rq_argp;
+	u8 uuid[UUID_SIZE];
+
+	if (decode_opaque_fixed(xdr, uuid, UUID_SIZE))
+		return false;
+	import_uuid(&argp->uuid, uuid);
+
+	return true;
+}
+
+static const struct svc_procedure localio_procedures1[] = {
+	[LOCALIOPROC_NULL] = {
+		.pc_func = localio_proc_null,
+		.pc_decode = nfssvc_decode_voidarg,
+		.pc_encode = nfssvc_encode_voidres,
+		.pc_argsize = sizeof(struct nfsd_voidargs),
+		.pc_ressize = sizeof(struct nfsd_voidres),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_xdrressize = 0,
+		.pc_name = "NULL",
+	},
+	[LOCALIOPROC_UUID_IS_LOCAL] = {
+		.pc_func = localio_proc_uuid_is_local,
+		.pc_decode = localio_decode_uuidarg,
+		.pc_encode = nfssvc_encode_voidres,
+		.pc_argsize = sizeof(struct localio_uuidarg),
+		.pc_argzero = sizeof(struct localio_uuidarg),
+		.pc_ressize = sizeof(struct nfsd_voidres),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_name = "UUID_IS_LOCAL",
+	},
+};
+
+#define LOCALIO_NR_PROCEDURES ARRAY_SIZE(localio_procedures1)
+static DEFINE_PER_CPU_ALIGNED(unsigned long,
+			      localio_count[LOCALIO_NR_PROCEDURES]);
+const struct svc_version localio_version1 = {
+	.vs_vers	= 1,
+	.vs_nproc	= LOCALIO_NR_PROCEDURES,
+	.vs_proc	= localio_procedures1,
+	.vs_dispatch	= nfsd_dispatch,
+	.vs_count	= localio_count,
+	.vs_xdrsize	= XDR_QUADLEN(UUID_SIZE),
+	.vs_hidden	= true,
+};
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index b0d3e82d6dcd..232a873dc53a 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -146,6 +146,10 @@ extern const struct svc_version nfsd_acl_version3;
 #endif
 #endif
 
+#if IS_ENABLED(CONFIG_NFSD_LOCALIO)
+extern const struct svc_version localio_version1;
+#endif
+
 struct nfsd_net;
 
 enum vers_op {NFSD_SET, NFSD_CLEAR, NFSD_TEST, NFSD_AVAIL };
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index c639fbe4d8c2..5f8680ab1013 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -79,6 +79,15 @@ DEFINE_SPINLOCK(nfsd_drc_lock);
 unsigned long	nfsd_drc_max_mem;
 unsigned long	nfsd_drc_mem_used;
 
+#if IS_ENABLED(CONFIG_NFSD_LOCALIO)
+static const struct svc_version *localio_versions[] = {
+	[1] = &localio_version1,
+};
+
+#define NFSD_LOCALIO_NRVERS		ARRAY_SIZE(localio_versions)
+
+#endif /* CONFIG_NFSD_LOCALIO */
+
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 static const struct svc_version *nfsd_acl_version[] = {
 # if defined(CONFIG_NFSD_V2_ACL)
@@ -127,6 +136,18 @@ struct svc_program		nfsd_programs[] = {
 	.pg_rpcbind_set		= nfsd_acl_rpcbind_set,
 	},
 #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
+#if IS_ENABLED(CONFIG_NFSD_LOCALIO)
+	{
+	.pg_prog		= NFS_LOCALIO_PROGRAM,
+	.pg_nvers		= NFSD_LOCALIO_NRVERS,
+	.pg_vers		= localio_versions,
+	.pg_name		= "nfslocalio",
+	.pg_class		= "nfsd",
+	.pg_authenticate	= svc_set_client,
+	.pg_init_request	= svc_generic_init_request,
+	.pg_rpcbind_set		= svc_generic_rpcbind_set,
+	}
+#endif /* IS_ENABLED(CONFIG_NFSD_LOCALIO) */
 };
 
 bool nfsd_support_version(int vers)
@@ -944,7 +965,7 @@ nfsd(void *vrqstp)
 }
 
 /**
- * nfsd_dispatch - Process an NFS or NFSACL Request
+ * nfsd_dispatch - Process an NFS or NFSACL or LOCALIO Request
  * @rqstp: incoming request
  *
  * This RPC dispatcher integrates the NFS server's duplicate reply cache.
diff --git a/include/linux/nfs.h b/include/linux/nfs.h
index ceb70a926b95..5ff1a5b3b00c 100644
--- a/include/linux/nfs.h
+++ b/include/linux/nfs.h
@@ -13,6 +13,13 @@
 #include <linux/crc32.h>
 #include <uapi/linux/nfs.h>
 
+/* The localio program is entirely private to Linux and is
+ * NOT part of the uapi.
+ */
+#define NFS_LOCALIO_PROGRAM		400122
+#define LOCALIOPROC_NULL		0
+#define LOCALIOPROC_UUID_IS_LOCAL	1
+
 /*
  * This is the kernel NFS client file handle representation
  */
-- 
2.44.0