path: root/fs/nfs/nfs2xdr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/nfs/nfs2xdr.c
 *
 * XDR functions to encode/decode NFS RPC arguments and results.
 *
 * Copyright (C) 1992, 1993, 1994  Rick Sladkey
 * Copyright (C) 1996 Olaf Kirch
 * 04 Aug 1998  Ion Badulescu <ionut@cs.columbia.edu>
 * 		FIFO's need special handling in NFSv2
 */

#include <linux/param.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/in.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs.h>
#include <linux/nfs2.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_common.h>
#include "nfstrace.h"
#include "internal.h"

#define NFSDBG_FACILITY		NFSDBG_XDR

/*
 * Declare the space requirements for NFS arguments and replies as
 * number of 32bit-words
 */
#define NFS_pagepad_sz		(1) /* Page padding */
#define NFS_fhandle_sz		(8)
#define NFS_sattr_sz		(8)
#define NFS_filename_sz		(1+(NFS2_MAXNAMLEN>>2))
#define NFS_path_sz		(1+(NFS2_MAXPATHLEN>>2))
#define NFS_fattr_sz		(17)
#define NFS_info_sz		(5)
#define NFS_entry_sz		(NFS_filename_sz+3)

#define NFS_diropargs_sz	(NFS_fhandle_sz+NFS_filename_sz)
#define NFS_removeargs_sz	(NFS_fhandle_sz+NFS_filename_sz)
#define NFS_sattrargs_sz	(NFS_fhandle_sz+NFS_sattr_sz)
#define NFS_readlinkargs_sz	(NFS_fhandle_sz)
#define NFS_readargs_sz		(NFS_fhandle_sz+3)
#define NFS_writeargs_sz	(NFS_fhandle_sz+4)
#define NFS_createargs_sz	(NFS_diropargs_sz+NFS_sattr_sz)
#define NFS_renameargs_sz	(NFS_diropargs_sz+NFS_diropargs_sz)
#define NFS_linkargs_sz		(NFS_fhandle_sz+NFS_diropargs_sz)
#define NFS_symlinkargs_sz	(NFS_diropargs_sz+1+NFS_sattr_sz)
#define NFS_readdirargs_sz	(NFS_fhandle_sz+2)

#define NFS_attrstat_sz		(1+NFS_fattr_sz)
#define NFS_diropres_sz		(1+NFS_fhandle_sz+NFS_fattr_sz)
#define NFS_readlinkres_sz	(2+NFS_pagepad_sz)
#define NFS_readres_sz		(1+NFS_fattr_sz+1+NFS_pagepad_sz)
#define NFS_writeres_sz         (NFS_attrstat_sz)
#define NFS_stat_sz		(1)
#define NFS_readdirres_sz	(1+NFS_pagepad_sz)
#define NFS_statfsres_sz	(1+NFS_info_sz)

/*
 * Encode/decode NFSv2 basic data types
 *
 * Basic NFSv2 data types are defined in section 2.3 of RFC 1094:
 * "NFS: Network File System Protocol Specification".
 *
 * Not all basic data types have their own encoding and decoding
 * functions.  For run-time efficiency, some data types are encoded
 * or decoded inline.
 */

static struct user_namespace *rpc_userns(const struct rpc_clnt *clnt)
{
	if (clnt && clnt->cl_cred)
		return clnt->cl_cred->user_ns;
	return &init_user_ns;
}

static struct user_namespace *rpc_rqst_userns(const struct rpc_rqst *rqstp)
{
	if (rqstp->rq_task)
		return rpc_userns(rqstp->rq_task->tk_client);
	return &init_user_ns;
}

/*
 *	typedef opaque	nfsdata<>;
 */
static int decode_nfsdata(struct xdr_stream *xdr, struct nfs_pgio_res *result)
{
	u32 recvd, count;
	__be32 *p;

	p = xdr_inline_decode(xdr, 4);
	if (unlikely(!p))
		return -EIO;
	count = be32_to_cpup(p);
	recvd = xdr_read_pages(xdr, count);
	if (unlikely(count > recvd))
		goto out_cheating;
out:
	result->eof = 0;	/* NFSv2 does not pass EOF flag on the wire. */
	result->count = count;
	return count;
out_cheating:
	dprintk("NFS: server cheating in read result: "
		"count %u > recvd %u\n", count, recvd);
	count = recvd;
	goto out;
}

/*
 *	enum stat {
 *		NFS_OK = 0,
 *		NFSERR_PERM = 1,
 *		NFSERR_NOENT = 2,
 *		NFSERR_IO = 5,
 *		NFSERR_NXIO = 6,
 *		NFSERR_ACCES = 13,
 *		NFSERR_EXIST = 17,
 *		NFSERR_NODEV = 19,
 *		NFSERR_NOTDIR = 20,
 *		NFSERR_ISDIR = 21,
 *		NFSERR_FBIG = 27,
 *		NFSERR_NOSPC = 28,
 *		NFSERR_ROFS = 30,
 *		NFSERR_NAMETOOLONG = 63,
 *		NFSERR_NOTEMPTY = 66,
 *		NFSERR_DQUOT = 69,
 *		NFSERR_STALE = 70,
 *		NFSERR_WFLUSH = 99
 *	};
 */
static int decode_stat(struct xdr_stream *xdr, enum nfs_stat *status)
{
	__be32 *p;

	p = xdr_inline_decode(xdr, 4);
	if (unlikely(!p))
		return -EIO;
	if (unlikely(*p != cpu_to_be32(NFS_OK)))
		goto out_status;
	*status = 0;
	return 0;
out_status:
	*status = be32_to_cpup(p);
	trace_nfs_xdr_status(xdr, (int)*status);
	return 0;
}

/*
 * 2.3.2.  ftype
 *
 *	enum ftype {
 *		NFNON = 0,
 *		NFREG = 1,
 *		NFDIR = 2,
 *		NFBLK = 3,
 *		NFCHR = 4,
 *		NFLNK = 5
 *	};
 *
 */
static __be32 *xdr_decode_ftype(__be32 *p, u32 *type)
{
	*type = be32_to_cpup(p++);
	if (unlikely(*type > NF2FIFO))
		*type = NFBAD;
	return p;
}

/*
 * 2.3.3.  fhandle
 *
 *	typedef opaque fhandle[FHSIZE];
 */
static void encode_fhandle(struct xdr_stream *xdr, const struct nfs_fh *fh)
{
	__be32 *p;

	p = xdr_reserve_space(xdr, NFS2_FHSIZE);
	memcpy(p, fh->data, NFS2_FHSIZE);
}

static int decode_fhandle(struct xdr_stream *xdr, struct nfs_fh *fh)
{
	__be32 *p;

	p = xdr_inline_decode(xdr, NFS2_FHSIZE);
	if (unlikely(!p))
		return -EIO;
	fh->size = NFS2_FHSIZE;
	memcpy(fh->data, p, NFS2_FHSIZE);
	return 0;
}

/*
 * 2.3.4.  timeval
 *
 *	struct timeval {
 *		unsigned int seconds;
 *		unsigned int useconds;
 *	};
 */
static __be32 *xdr_encode_time(__be32 *p, const struct timespec64 *timep)
{
	*p++ = cpu_to_be32((u32)timep->tv_sec);
	if (timep->tv_nsec != 0)
		*p++ = cpu_to_be32(timep->tv_nsec / NSEC_PER_USEC);
	else
		*p++ = cpu_to_be32(0);
	return p;
}

/*
 * Passing the invalid value useconds=1000000 is a Sun convention for
 * "