Re: [PATCH v14 17/25] nfsd: implement server support for NFS_LOCALIO_PROGRAM

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2024-08-28 at 21:04 -0400, Mike Snitzer wrote:
> 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.  The server expects this protocol to use
> the same transport as NFS and NFSACL for its RPCs.  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
> 
> Acked-by: Chuck Lever <chuck.lever@oracle.com>
> 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 4b65c66be129..a192bbe308df 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 nfsd_file
> @@ -103,3 +106,75 @@ 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 13c69aa40d1c..eec4a9803c4a 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -80,6 +80,15 @@ 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)
> @@ -128,6 +137,18 @@ 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)
> @@ -949,7 +970,7 @@ 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
>   */

Reviewed-by: Jeff Layton <jlayton@kernel.org>