text: // SPDX-License-Identifier: GPL-2.0
  /*
   * linux/fs/nfs/callback_xdr.c
   *
   * Copyright (C) 2004 Trond Myklebust
   *
   * NFSv4 callback encode/decode procedures
   */
  #include <linux/kernel.h>
  #include <linux/sunrpc/svc.h>
  #include <linux/nfs4.h>
  #include <linux/nfs_fs.h>
  #include <linux/ratelimit.h>
  #include <linux/printk.h>
  #include <linux/slab.h>
  #include <linux/sunrpc/bc_xprt.h>
  #include "nfs4_fs.h"
  #include "callback.h"
  #include "internal.h"
  #include "nfs4session.h"
  
  #define CB_OP_TAGLEN_MAXSZ		(512)
  #define CB_OP_HDR_RES_MAXSZ		(2 * 4) // opcode, status
  #define CB_OP_GETATTR_BITMAP_MAXSZ	(4 * 4) // bitmap length, 3 bitmaps
  #define CB_OP_GETATTR_RES_MAXSZ		(CB_OP_HDR_RES_MAXSZ + \
  					 CB_OP_GETATTR_BITMAP_MAXSZ + \
  					 /* change, size, ctime, mtime */\
  					 (2 + 2 + 3 + 3) * 4)
  #define CB_OP_RECALL_RES_MAXSZ		(CB_OP_HDR_RES_MAXSZ)
  
  #if defined(CONFIG_NFS_V4_1)
  #define CB_OP_LAYOUTRECALL_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ)
  #define CB_OP_DEVICENOTIFY_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ)
  #define CB_OP_SEQUENCE_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ + \
  					 NFS4_MAX_SESSIONID_LEN + \
  					 (1 + 3) * 4) // seqid, 3 slotids
  #define CB_OP_RECALLANY_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ)
  #define CB_OP_RECALLSLOT_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ)
  #define CB_OP_NOTIFY_LOCK_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ)
  #endif /* CONFIG_NFS_V4_1 */
  #ifdef CONFIG_NFS_V4_2
  #define CB_OP_OFFLOAD_RES_MAXSZ		(CB_OP_HDR_RES_MAXSZ)
  #endif /* CONFIG_NFS_V4_2 */
  
  #define NFSDBG_FACILITY NFSDBG_CALLBACK
  
  /* Internal error code */
  #define NFS4ERR_RESOURCE_HDR	11050
  
  struct callback_op {
  	__be32 (*process_op)(void *, void *, struct cb_process_state *);
  	__be32 (*decode_args)(struct svc_rqst *, struct xdr_stream *, void *);
  	__be32 (*encode_res)(struct svc_rqst *, struct xdr_stream *,
  			const void *);
  	long res_maxsize;
  };
  
  static struct callback_op callback_ops[];
  
  static __be32 nfs4_callback_null(struct svc_rqst *rqstp)
  {
  	return htonl(NFS4_OK);
  }
  
  static int nfs4_decode_void(struct svc_rqst *rqstp, __be32 *p)
  {
  	return xdr_argsize_check(rqstp, p);
  }
  
  static int nfs4_encode_void(struct svc_rqst *rqstp, __be32 *p)
  {
  	return xdr_ressize_check(rqstp, p);
  }
  
  static __be32 decode_string(struct xdr_stream *xdr, unsigned int *len,
  		const char **str, size_t maxlen)
  {
  	ssize_t err;
  
  	err = xdr_stream_decode_opaque_inline(xdr, (void **)str, maxlen);
  	if (err < 0)
  		return cpu_to_be32(NFS4ERR_RESOURCE);
  	*len = err;
  	return 0;
  }
  
  static __be32 decode_fh(struct xdr_stream *xdr, struct nfs_fh *fh)
  {
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	fh->size = ntohl(*p);
  	if (fh->size > NFS4_FHSIZE)
  		return htonl(NFS4ERR_BADHANDLE);
  	p = xdr_inline_decode(xdr, fh->size);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	memcpy(&fh->data[0], p, fh->size);
  	memset(&fh->data[fh->size], 0, sizeof(fh->data) - fh->size);
  	return 0;
  }
  
  static __be32 decode_bitmap(struct xdr_stream *xdr, uint32_t *bitmap)
  {
  	__be32 *p;
  	unsigned int attrlen;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	attrlen = ntohl(*p);
  	p = xdr_inline_decode(xdr, attrlen << 2);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	if (likely(attrlen > 0))
  		bitmap[0] = ntohl(*p++);
  	if (attrlen > 1)
  		bitmap[1] = ntohl(*p);
  	return 0;
  }
  
  static __be32 decode_stateid(struct xdr_stream *xdr, nfs4_stateid *stateid)
  {
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, NFS4_STATEID_SIZE);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	memcpy(stateid->data, p, NFS4_STATEID_SIZE);
  	return 0;
  }
  
  static __be32 decode_delegation_stateid(struct xdr_stream *xdr, nfs4_stateid *stateid)
  {
  	stateid->type = NFS4_DELEGATION_STATEID_TYPE;
  	return decode_stateid(xdr, stateid);
  }
  
  static __be32 decode_compound_hdr_arg(struct xdr_stream *xdr, struct cb_compound_hdr_arg *hdr)
  {
  	__be32 *p;
  	__be32 status;
  
  	status = decode_string(xdr, &hdr->taglen, &hdr->tag, CB_OP_TAGLEN_MAXSZ);
  	if (unlikely(status != 0))
  		return status;
  	p = xdr_inline_decode(xdr, 12);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	hdr->minorversion = ntohl(*p++);
  	/* Check for minor version support */
  	if (hdr->minorversion <= NFS4_MAX_MINOR_VERSION) {
  		hdr->cb_ident = ntohl(*p++); /* ignored by v4.1 and v4.2 */
  	} else {
  		pr_warn_ratelimited("NFS: %s: NFSv4 server callback with "
  			"illegal minor version %u!\n",
  			__func__, hdr->minorversion);
  		return htonl(NFS4ERR_MINOR_VERS_MISMATCH);
  	}
  	hdr->nops = ntohl(*p);
  	return 0;
  }
  
  static __be32 decode_op_hdr(struct xdr_stream *xdr, unsigned int *op)
  {
  	__be32 *p;
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE_HDR);
  	*op = ntohl(*p);
  	return 0;
  }
  
  static __be32 decode_getattr_args(struct svc_rqst *rqstp,
  		struct xdr_stream *xdr, void *argp)
  {
  	struct cb_getattrargs *args = argp;
  	__be32 status;
  
  	status = decode_fh(xdr, &args->fh);
  	if (unlikely(status != 0))
  		return status;
  	return decode_bitmap(xdr, args->bitmap);
  }
  
  static __be32 decode_recall_args(struct svc_rqst *rqstp,
  		struct xdr_stream *xdr, void *argp)
  {
  	struct cb_recallargs *args = argp;
  	__be32 *p;
  	__be32 status;
  
  	status = decode_delegation_stateid(xdr, &args->stateid);
  	if (unlikely(status != 0))
  		return status;
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	args->truncate = ntohl(*p);
  	return decode_fh(xdr, &args->fh);
  }
  
  #if defined(CONFIG_NFS_V4_1)
  static __be32 decode_layout_stateid(struct xdr_stream *xdr, nfs4_stateid *stateid)
  {
  	stateid->type = NFS4_LAYOUT_STATEID_TYPE;
  	return decode_stateid(xdr, stateid);
  }
  
  static __be32 decode_layoutrecall_args(struct svc_rqst *rqstp,
  				       struct xdr_stream *xdr, void *argp)
  {
  	struct cb_layoutrecallargs *args = argp;
  	__be32 *p;
  	__be32 status = 0;
  	uint32_t iomode;
  
  	p = xdr_inline_decode(xdr, 4 * sizeof(uint32_t));
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_BADXDR);
  
  	args->cbl_layout_type = ntohl(*p++);
  	/* Depite the spec's xdr, iomode really belongs in the FILE switch,
  	 * as it is unusable and ignored with the other types.
  	 */
  	iomode = ntohl(*p++);
  	args->cbl_layoutchanged = ntohl(*p++);
  	args->cbl_recall_type = ntohl(*p++);
  
  	if (args->cbl_recall_type == RETURN_FILE) {
  		args->cbl_range.iomode = iomode;
  		status = decode_fh(xdr, &args->cbl_fh);
  		if (unlikely(status != 0))
  			return status;
  
  		p = xdr_inline_decode(xdr, 2 * sizeof(uint64_t));
  		if (unlikely(p == NULL))
  			return htonl(NFS4ERR_BADXDR);
  		p = xdr_decode_hyper(p, &args->cbl_range.offset);
  		p = xdr_decode_hyper(p, &args->cbl_range.length);
  		return decode_layout_stateid(xdr, &args->cbl_stateid);
  	} else if (args->cbl_recall_type == RETURN_FSID) {
  		p = xdr_inline_decode(xdr, 2 * sizeof(uint64_t));
  		if (unlikely(p == NULL))
  			return htonl(NFS4ERR_BADXDR);
  		p = xdr_decode_hyper(p, &args->cbl_fsid.major);
  		p = xdr_decode_hyper(p, &args->cbl_fsid.minor);
  	} else if (args->cbl_recall_type != RETURN_ALL)
  		return htonl(NFS4ERR_BADXDR);
  	return 0;
  }
  
  static
  __be32 decode_devicenotify_args(struct svc_rqst *rqstp,
  				struct xdr_stream *xdr,
  				void *argp)
  {
  	struct cb_devicenotifyargs *args = argp;
  	__be32 *p;
  	__be32 status = 0;
  	u32 tmp;
  	int n, i;
  	args->ndevs = 0;
  
  	/* Num of device notifications */
  	p = xdr_inline_decode(xdr, sizeof(uint32_t));
  	if (unlikely(p == NULL)) {
  		status = htonl(NFS4ERR_BADXDR);
  		goto out;
  	}
  	n = ntohl(*p++);
  	if (n <= 0)
  		goto out;
  	if (n > ULONG_MAX / sizeof(*args->devs)) {
  		status = htonl(NFS4ERR_BADXDR);
  		goto out;
  	}
  
  	args->devs = kmalloc_array(n, sizeof(*args->devs), GFP_KERNEL);
  	if (!args->devs) {
  		status = htonl(NFS4ERR_DELAY);
  		goto out;
  	}
  
  	/* Decode each dev notification */
  	for (i = 0; i < n; i++) {
  		struct cb_devicenotifyitem *dev = &args->devs[i];
  
  		p = xdr_inline_decode(xdr, (4 * sizeof(uint32_t)) +
  				      NFS4_DEVICEID4_SIZE);
  		if (unlikely(p == NULL)) {
  			status = htonl(NFS4ERR_BADXDR);
  			goto err;
  		}
  
  		tmp = ntohl(*p++);	/* bitmap size */
  		if (tmp != 1) {
  			status = htonl(NFS4ERR_INVAL);
  			goto err;
  		}
  		dev->cbd_notify_type = ntohl(*p++);
  		if (dev->cbd_notify_type != NOTIFY_DEVICEID4_CHANGE &&
  		    dev->cbd_notify_type != NOTIFY_DEVICEID4_DELETE) {
  			status = htonl(NFS4ERR_INVAL);
  			goto err;
  		}
  
  		tmp = ntohl(*p++);	/* opaque size */
  		if (((dev->cbd_notify_type == NOTIFY_DEVICEID4_CHANGE) &&
  		     (tmp != NFS4_DEVICEID4_SIZE + 8)) ||
  		    ((dev->cbd_notify_type == NOTIFY_DEVICEID4_DELETE) &&
  		     (tmp != NFS4_DEVICEID4_SIZE + 4))) {
  			status = htonl(NFS4ERR_INVAL);
  			goto err;
  		}
  		dev->cbd_layout_type = ntohl(*p++);
  		memcpy(dev->cbd_dev_id.data, p, NFS4_DEVICEID4_SIZE);
  		p += XDR_QUADLEN(NFS4_DEVICEID4_SIZE);
  
  		if (dev->cbd_layout_type == NOTIFY_DEVICEID4_CHANGE) {
  			p = xdr_inline_decode(xdr, sizeof(uint32_t));
  			if (unlikely(p == NULL)) {
  				status = htonl(NFS4ERR_BADXDR);
  				goto err;
  			}
  			dev->cbd_immediate = ntohl(*p++);
  		} else {
  			dev->cbd_immediate = 0;
  		}
  
  		args->ndevs++;
  
  		dprintk("%s: type %d layout 0x%x immediate %d\n",
  			__func__, dev->cbd_notify_type, dev->cbd_layout_type,
  			dev->cbd_immediate);
  	}
  out:
  	dprintk("%s: status %d ndevs %d\n",
  		__func__, ntohl(status), args->ndevs);
  	return status;
  err:
  	kfree(args->devs);
  	goto out;
  }
  
  static __be32 decode_sessionid(struct xdr_stream *xdr,
  				 struct nfs4_sessionid *sid)
  {
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, NFS4_MAX_SESSIONID_LEN);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  
  	memcpy(sid->data, p, NFS4_MAX_SESSIONID_LEN);
  	return 0;
  }
  
  static __be32 decode_rc_list(struct xdr_stream *xdr,
  			       struct referring_call_list *rc_list)
  {
  	__be32 *p;
  	int i;
  	__be32 status;
  
  	status = decode_sessionid(xdr, &rc_list->rcl_sessionid);
  	if (status)
  		goto out;
  
  	status = htonl(NFS4ERR_RESOURCE);
  	p = xdr_inline_decode(xdr, sizeof(uint32_t));
  	if (unlikely(p == NULL))
  		goto out;
  
  	rc_list->rcl_nrefcalls = ntohl(*p++);
  	if (rc_list->rcl_nrefcalls) {
  		p = xdr_inline_decode(xdr,
  			     rc_list->rcl_nrefcalls * 2 * sizeof(uint32_t));
  		if (unlikely(p == NULL))
  			goto out;
  		rc_list->rcl_refcalls = kmalloc_array(rc_list->rcl_nrefcalls,
  						sizeof(*rc_list->rcl_refcalls),
  						GFP_KERNEL);
  		if (unlikely(rc_list->rcl_refcalls == NULL))
  			goto out;
  		for (i = 0; i < rc_list->rcl_nrefcalls; i++) {
  			rc_list->rcl_refcalls[i].rc_sequenceid = ntohl(*p++);
  			rc_list->rcl_refcalls[i].rc_slotid = ntohl(*p++);
  		}
  	}
  	status = 0;
  
  out:
  	return status;
  }
  
  static __be32 decode_cb_sequence_args(struct svc_rqst *rqstp,
  					struct xdr_stream *xdr,
  					void *argp)
  {
  	struct cb_sequenceargs *args = argp;
  	__be32 *p;
  	int i;
  	__be32 status;
  
  	status = decode_sessionid(xdr, &args->csa_sessionid);
  	if (status)
  		return status;
  
  	p = xdr_inline_decode(xdr, 5 * sizeof(uint32_t));
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  
  	args->csa_addr = svc_addr(rqstp);
  	args->csa_sequenceid = ntohl(*p++);
  	args->csa_slotid = ntohl(*p++);
  	args->csa_highestslotid = ntohl(*p++);
  	args->csa_cachethis = ntohl(*p++);
  	args->csa_nrclists = ntohl(*p++);
  	args->csa_rclists = NULL;
  	if (args->csa_nrclists) {
  		args->csa_rclists = kmalloc_array(args->csa_nrclists,
  						  sizeof(*args->csa_rclists),
  						  GFP_KERNEL);
  		if (unlikely(args->csa_rclists == NULL))
  			return htonl(NFS4ERR_RESOURCE);
  
  		for (i = 0; i < args->csa_nrclists; i++) {
  			status = decode_rc_list(xdr, &args->csa_rclists[i]);
  			if (status) {
  				args->csa_nrclists = i;
  				goto out_free;
  			}
  		}
  	}
  	return 0;
  
  out_free:
  	for (i = 0; i < args->csa_nrclists; i++)
  		kfree(args->csa_rclists[i].rcl_refcalls);
  	kfree(args->csa_rclists);
  	return status;
  }
  
  static __be32 decode_recallany_args(struct svc_rqst *rqstp,
  				      struct xdr_stream *xdr,
  				      void *argp)
  {
  	struct cb_recallanyargs *args = argp;
  	uint32_t bitmap[2];
  	__be32 *p, status;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_BADXDR);
  	args->craa_objs_to_keep = ntohl(*p++);
  	status = decode_bitmap(xdr, bitmap);
  	if (unlikely(status))
  		return status;
  	args->craa_type_mask = bitmap[0];
  
  	return 0;
  }
  
  static __be32 decode_recallslot_args(struct svc_rqst *rqstp,
  					struct xdr_stream *xdr,
  					void *argp)
  {
  	struct cb_recallslotargs *args = argp;
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_BADXDR);
  	args->crsa_target_highest_slotid = ntohl(*p++);
  	return 0;
  }
  
  static __be32 decode_lockowner(struct xdr_stream *xdr, struct cb_notify_lock_args *args)
  {
  	__be32		*p;
  	unsigned int	len;
  
  	p = xdr_inline_decode(xdr, 12);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_BADXDR);
  
  	p = xdr_decode_hyper(p, &args->cbnl_owner.clientid);
  	len = be32_to_cpu(*p);
  
  	p = xdr_inline_decode(xdr, len);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_BADXDR);
  
  	/* Only try to decode if the length is right */
  	if (len == 20) {
  		p += 2;	/* skip "lock id:" */
  		args->cbnl_owner.s_dev = be32_to_cpu(*p++);
  		xdr_decode_hyper(p, &args->cbnl_owner.id);
  		args->cbnl_valid = true;
  	} else {
  		args->cbnl_owner.s_dev = 0;
  		args->cbnl_owner.id = 0;
  		args->cbnl_valid = false;
  	}
  	return 0;
  }
  
  static __be32 decode_notify_lock_args(struct svc_rqst *rqstp,
  		struct xdr_stream *xdr, void *argp)
  {
  	struct cb_notify_lock_args *args = argp;
  	__be32 status;
  
  	status = decode_fh(xdr, &args->cbnl_fh);
  	if (unlikely(status != 0))
  		return status;
  	return decode_lockowner(xdr, args);
  }
  
  #endif /* CONFIG_NFS_V4_1 */
  #ifdef CONFIG_NFS_V4_2
  static __be32 decode_write_response(struct xdr_stream *xdr,
  					struct cb_offloadargs *args)
  {
  	__be32 *p;
  
  	/* skip the always zero field */
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(!p))
  		goto out;
  	p++;
  
  	/* decode count, stable_how, verifier */
  	p = xdr_inline_decode(xdr, 8 + 4);
  	if (unlikely(!p))
  		goto out;
  	p = xdr_decode_hyper(p, &args->wr_count);
  	args->wr_writeverf.committed = be32_to_cpup(p);
  	p = xdr_inline_decode(xdr, NFS4_VERIFIER_SIZE);
  	if (likely(p)) {
  		memcpy(&args->wr_writeverf.verifier.data[0], p,
  			NFS4_VERIFIER_SIZE);
  		return 0;
  	}
  out:
  	return htonl(NFS4ERR_RESOURCE);
  }
  
  static __be32 decode_offload_args(struct svc_rqst *rqstp,
  					struct xdr_stream *xdr,
  					void *data)
  {
  	struct cb_offloadargs *args = data;
  	__be32 *p;
  	__be32 status;
  
  	/* decode fh */
  	status = decode_fh(xdr, &args->coa_fh);
  	if (unlikely(status != 0))
  		return status;
  
  	/* decode stateid */
  	status = decode_stateid(xdr, &args->coa_stateid);
  	if (unlikely(status != 0))
  		return status;
  
  	/* decode status */
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(!p))
  		goto out;
  	args->error = ntohl(*p++);
  	if (!args->error) {
  		status = decode_write_response(xdr, args);
  		if (unlikely(status != 0))
  			return status;
  	} else {
  		p = xdr_inline_decode(xdr, 8);
  		if (unlikely(!p))
  			goto out;
  		p = xdr_decode_hyper(p, &args->wr_count);
  	}
  	return 0;
  out:
  	return htonl(NFS4ERR_RESOURCE);
  }
  #endif /* CONFIG_NFS_V4_2 */
  static __be32 encode_string(struct xdr_stream *xdr, unsigned int len, const char *str)
  {
  	if (unlikely(xdr_stream_encode_opaque(xdr, str, len) < 0))
  		return cpu_to_be32(NFS4ERR_RESOURCE);
  	return 0;
  }
  
  static __be32 encode_attr_bitmap(struct xdr_stream *xdr, const uint32_t *bitmap, size_t sz)
  {
  	if (xdr_stream_encode_uint32_array(xdr, bitmap, sz) < 0)
  		return cpu_to_be32(NFS4ERR_RESOURCE);
  	return 0;
  }
  
  static __be32 encode_attr_change(struct xdr_stream *xdr, const uint32_t *bitmap, uint64_t change)
  {
  	__be32 *p;
  
  	if (!(bitmap[0] & FATTR4_WORD0_CHANGE))
  		return 0;
  	p = xdr_reserve_space(xdr, 8);
  	if (unlikely(!p))
  		return htonl(NFS4ERR_RESOURCE);
  	p = xdr_encode_hyper(p, change);
  	return 0;
  }
  
  static __be32 encode_attr_size(struct xdr_stream *xdr, const uint32_t *bitmap, uint64_t size)
  {
  	__be32 *p;
  
  	if (!(bitmap[0] & FATTR4_WORD0_SIZE))
  		return 0;
  	p = xdr_reserve_space(xdr, 8);
  	if (unlikely(!p))
  		return htonl(NFS4ERR_RESOURCE);
  	p = xdr_encode_hyper(p, size);
  	return 0;
  }
  
  static __be32 encode_attr_time(struct xdr_stream *xdr, const struct timespec *time)
  {
  	__be32 *p;
  
  	p = xdr_reserve_space(xdr, 12);
  	if (unlikely(!p))
  		return htonl(NFS4ERR_RESOURCE);
  	p = xdr_encode_hyper(p, time->tv_sec);
  	*p = htonl(time->tv_nsec);
  	return 0;
  }
  
  static __be32 encode_attr_ctime(struct xdr_stream *xdr, const uint32_t *bitmap, const struct timespec *time)
  {
  	if (!(bitmap[1] & FATTR4_WORD1_TIME_METADATA))
  		return 0;
  	return encode_attr_time(xdr,time);
  }
  
  static __be32 encode_attr_mtime(struct xdr_stream *xdr, const uint32_t *bitmap, const struct timespec *time)
  {
  	if (!(bitmap[1] & FATTR4_WORD1_TIME_MODIFY))
  		return 0;
  	return encode_attr_time(xdr,time);
  }
  
  static __be32 encode_compound_hdr_res(struct xdr_stream *xdr, struct cb_compound_hdr_res *hdr)
  {
  	__be32 status;
  
  	hdr->status = xdr_reserve_space(xdr, 4);
  	if (unlikely(hdr->status == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	status = encode_string(xdr, hdr->taglen, hdr->tag);
  	if (unlikely(status != 0))
  		return status;
  	hdr->nops = xdr_reserve_space(xdr, 4);
  	if (unlikely(hdr->nops == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  	return 0;
  }
  
  static __be32 encode_op_hdr(struct xdr_stream *xdr, uint32_t op, __be32 res)
  {
  	__be32 *p;
  	
  	p = xdr_reserve_space(xdr, 8);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE_HDR);
  	*p++ = htonl(op);
  	*p = res;
  	return 0;
  }
  
  static __be32 encode_getattr_res(struct svc_rqst *rqstp, struct xdr_stream *xdr,
  		const void *resp)
  {
  	const struct cb_getattrres *res = resp;
  	__be32 *savep = NULL;
  	__be32 status = res->status;
  	
  	if (unlikely(status != 0))
  		goto out;
  	status = encode_attr_bitmap(xdr, res->bitmap, ARRAY_SIZE(res->bitmap));
  	if (unlikely(status != 0))
  		goto out;
  	status = cpu_to_be32(NFS4ERR_RESOURCE);
  	savep = xdr_reserve_space(xdr, sizeof(*savep));
  	if (unlikely(!savep))
  		goto out;
  	status = encode_attr_change(xdr, res->bitmap, res->change_attr);
  	if (unlikely(status != 0))
  		goto out;
  	status = encode_attr_size(xdr, res->bitmap, res->size);
  	if (unlikely(status != 0))
  		goto out;
  	status = encode_attr_ctime(xdr, res->bitmap, &res->ctime);
  	if (unlikely(status != 0))
  		goto out;
  	status = encode_attr_mtime(xdr, res->bitmap, &res->mtime);
  	*savep = htonl((unsigned int)((char *)xdr->p - (char *)(savep+1)));
  out:
  	return status;
  }
  
  #if defined(CONFIG_NFS_V4_1)
  
  static __be32 encode_sessionid(struct xdr_stream *xdr,
  				 const struct nfs4_sessionid *sid)
  {
  	__be32 *p;
  
  	p = xdr_reserve_space(xdr, NFS4_MAX_SESSIONID_LEN);
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  
  	memcpy(p, sid, NFS4_MAX_SESSIONID_LEN);
  	return 0;
  }
  
  static __be32 encode_cb_sequence_res(struct svc_rqst *rqstp,
  				       struct xdr_stream *xdr,
  				       const void *resp)
  {
  	const struct cb_sequenceres *res = resp;
  	__be32 *p;
  	__be32 status = res->csr_status;
  
  	if (unlikely(status != 0))
  		return status;
  
  	status = encode_sessionid(xdr, &res->csr_sessionid);
  	if (status)
  		return status;
  
  	p = xdr_reserve_space(xdr, 4 * sizeof(uint32_t));
  	if (unlikely(p == NULL))
  		return htonl(NFS4ERR_RESOURCE);
  
  	*p++ = htonl(res->csr_sequenceid);
  	*p++ = htonl(res->csr_slotid);
  	*p++ = htonl(res->csr_highestslotid);
  	*p++ = htonl(res->csr_target_highestslotid);
  	return 0;
  }
  
  static __be32
  preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
  {
  	if (op_nr == OP_CB_SEQUENCE) {
  		if (nop != 0)
  			return htonl(NFS4ERR_SEQUENCE_POS);
  	} else {
  		if (nop == 0)
  			return htonl(NFS4ERR_OP_NOT_IN_SESSION);
  	}
  
  	switch (op_nr) {
  	case OP_CB_GETATTR:
  	case OP_CB_RECALL:
  	case OP_CB_SEQUENCE:
  	case OP_CB_RECALL_ANY:
  	case OP_CB_RECALL_SLOT:
  	case OP_CB_LAYOUTRECALL:
  	case OP_CB_NOTIFY_DEVICEID:
  	case OP_CB_NOTIFY_LOCK:
  		*op = &callback_ops[op_nr];
  		break;
  
  	case OP_CB_NOTIFY:
  	case OP_CB_PUSH_DELEG:
  	case OP_CB_RECALLABLE_OBJ_AVAIL:
  	case OP_CB_WANTS_CANCELLED:
  		return htonl(NFS4ERR_NOTSUPP);
  
  	default:
  		return htonl(NFS4ERR_OP_ILLEGAL);
  	}
  
  	return htonl(NFS_OK);
  }
  
  static void nfs4_callback_free_slot(struct nfs4_session *session,
  		struct nfs4_slot *slot)
  {
  	struct nfs4_slot_table *tbl = &session->bc_slot_table;
  
  	spin_lock(&tbl->slot_tbl_lock);
  	/*
  	 * Let the state manager know callback processing done.
  	 * A single slot, so highest used slotid is either 0 or -1
  	 */
  	nfs4_free_slot(tbl, slot);
  	spin_unlock(&tbl->slot_tbl_lock);
  }
  
  static void nfs4_cb_free_slot(struct cb_process_state *cps)
  {
  	if (cps->slot) {
  		nfs4_callback_free_slot(cps->clp->cl_session, cps->slot);
  		cps->slot = NULL;
  	}
  }
  
  #else /* CONFIG_NFS_V4_1 */
  
  static __be32
  preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
  {
  	return htonl(NFS4ERR_MINOR_VERS_MISMATCH);
  }
  
  static void nfs4_cb_free_slot(struct cb_process_state *cps)
  {
  }
  #endif /* CONFIG_NFS_V4_1 */
  
  #ifdef CONFIG_NFS_V4_2
  static __be32
  preprocess_nfs42_op(int nop, unsigned int op_nr, struct callback_op **op)
  {
  	__be32 status = preprocess_nfs41_op(nop, op_nr, op);
  	if (status != htonl(NFS4ERR_OP_ILLEGAL))
  		return status;
  
  	if (op_nr == OP_CB_OFFLOAD) {
  		*op = &callback_ops[op_nr];
  		return htonl(NFS_OK);
  	} else
  		return htonl(NFS4ERR_NOTSUPP);
  	return htonl(NFS4ERR_OP_ILLEGAL);
  }
  #else /* CONFIG_NFS_V4_2 */
  static __be32
  preprocess_nfs42_op(int nop, unsigned int op_nr, struct callback_op **op)
  {
  	return htonl(NFS4ERR_MINOR_VERS_MISMATCH);
  }
  #endif /* CONFIG_NFS_V4_2 */
  
  static __be32
  preprocess_nfs4_op(unsigned int op_nr, struct callback_op **op)
  {
  	switch (op_nr) {
  	case OP_CB_GETATTR:
  	case OP_CB_RECALL:
  		*op = &callback_ops[op_nr];
  		break;
  	default:
  		return htonl(NFS4ERR_OP_ILLEGAL);
  	}
  
  	return htonl(NFS_OK);
  }
  
  static __be32 process_op(int nop, struct svc_rqst *rqstp,
  		struct xdr_stream *xdr_in, void *argp,
  		struct xdr_stream *xdr_out, void *resp,
  		struct cb_process_state *cps)
  {
  	struct callback_op *op = &callback_ops[0];
  	unsigned int op_nr;
  	__be32 status;
  	long maxlen;
  	__be32 res;
  
  	status = decode_op_hdr(xdr_in, &op_nr);
  	if (unlikely(status))
  		return status;
  
  	switch (cps->minorversion) {
  	case 0:
  		status = preprocess_nfs4_op(op_nr, &op);
  		break;
  	case 1:
  		status = preprocess_nfs41_op(nop, op_nr, &op);
  		break;
  	case 2:
  		status = preprocess_nfs42_op(nop, op_nr, &op);
  		break;
  	default:
  		status = htonl(NFS4ERR_MINOR_VERS_MISMATCH);
  	}
  
  	if (status == htonl(NFS4ERR_OP_ILLEGAL))
  		op_nr = OP_CB_ILLEGAL;
  	if (status)
  		goto encode_hdr;
  
  	if (cps->drc_status) {
  		status = cps->drc_status;
  		goto encode_hdr;
  	}
  
  	maxlen = xdr_out->end - xdr_out->p;
  	if (maxlen > 0 && maxlen < PAGE_SIZE) {
  		status = op->decode_args(rqstp, xdr_in, argp);
  		if (likely(status == 0))
  			status = op->process_op(argp, resp, cps);
  	} else
  		status = htonl(NFS4ERR_RESOURCE);
  
  encode_hdr:
  	res = encode_op_hdr(xdr_out, op_nr, status);
  	if (unlikely(res))
  		return res;
  	if (op->encode_res != NULL && status == 0)
  		status = op->encode_res(rqstp, xdr_out, resp);
  	return status;
  }
  
  /*
   * Decode, process and encode a COMPOUND
   */
  static __be32 nfs4_callback_compound(struct svc_rqst *rqstp)
  {
  	struct cb_compound_hdr_arg hdr_arg = { 0 };
  	struct cb_compound_hdr_res hdr_res = { NULL };
  	struct xdr_stream xdr_in, xdr_out;
  	__be32 *p, status;
  	struct cb_process_state cps = {
  		.drc_status = 0,
  		.clp = NULL,
  		.net = SVC_NET(rqstp),
  	};
  	unsigned int nops = 0;
  
  	xdr_init_decode(&xdr_in, &rqstp->rq_arg,
  			rqstp->rq_arg.head[0].iov_base, NULL);
  
  	p = (__be32*)((char *)rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len);
  	xdr_init_encode(&xdr_out, &rqstp->rq_res, p, NULL);
  
  	status = decode_compound_hdr_arg(&xdr_in, &hdr_arg);
  	if (status == htonl(NFS4ERR_RESOURCE))
  		return rpc_garbage_args;
  
  	if (hdr_arg.minorversion == 0) {
  		cps.clp = nfs4_find_client_ident(SVC_NET(rqstp), hdr_arg.cb_ident);
  		if (!cps.clp || !check_gss_callback_principal(cps.clp, rqstp)) {
  			if (cps.clp)
  				nfs_put_client(cps.clp);
  			goto out_invalidcred;
  		}
  	}
  
  	cps.minorversion = hdr_arg.minorversion;
  	hdr_res.taglen = hdr_arg.taglen;
  	hdr_res.tag = hdr_arg.tag;
  	if (encode_compound_hdr_res(&xdr_out, &hdr_res) != 0) {
  		if (cps.clp)
  			nfs_put_client(cps.clp);
  		return rpc_system_err;
  	}
  	while (status == 0 && nops != hdr_arg.nops) {
  		status = process_op(nops, rqstp, &xdr_in,
  				    rqstp->rq_argp, &xdr_out, rqstp->rq_resp,
  				    &cps);
  		nops++;
  	}
  
  	/* Buffer overflow in decode_ops_hdr or encode_ops_hdr. Return
  	* resource error in cb_compound status without returning op */
  	if (unlikely(status == htonl(NFS4ERR_RESOURCE_HDR))) {
  		status = htonl(NFS4ERR_RESOURCE);
  		nops--;
  	}
  
  	*hdr_res.status = status;
  	*hdr_res.nops = htonl(nops);
  	nfs4_cb_free_slot(&cps);
  	nfs_put_client(cps.clp);
  	return rpc_success;
  
  out_invalidcred:
  	pr_warn_ratelimited("NFS: NFSv4 callback contains invalid cred\n");
  	return rpc_autherr_badcred;
  }
  
  /*
   * Define NFS4 callback COMPOUND ops.
   */
  static struct callback_op callback_ops[] = {
  	[0] = {
  		.res_maxsize = CB_OP_HDR_RES_MAXSZ,
  	},
  	[OP_CB_GETATTR] = {
  		.process_op = nfs4_callback_getattr,
  		.decode_args = decode_getattr_args,
  		.encode_res = encode_getattr_res,
  		.res_maxsize = CB_OP_GETATTR_RES_MAXSZ,
  	},
  	[OP_CB_RECALL] = {
  		.process_op = nfs4_callback_recall,
  		.decode_args = decode_recall_args,
  		.res_maxsize = CB_OP_RECALL_RES_MAXSZ,
  	},
  #if defined(CONFIG_NFS_V4_1)
  	[OP_CB_LAYOUTRECALL] = {
  		.process_op = nfs4_callback_layoutrecall,
  		.decode_args = decode_layoutrecall_args,
  		.res_maxsize = CB_OP_LAYOUTRECALL_RES_MAXSZ,
  	},
  	[OP_CB_NOTIFY_DEVICEID] = {
  		.process_op = nfs4_callback_devicenotify,
  		.decode_args = decode_devicenotify_args,
  		.res_maxsize = CB_OP_DEVICENOTIFY_RES_MAXSZ,
  	},
  	[OP_CB_SEQUENCE] = {
  		.process_op = nfs4_callback_sequence,
  		.decode_args = decode_cb_sequence_args,
  		.encode_res = encode_cb_sequence_res,
  		.res_maxsize = CB_OP_SEQUENCE_RES_MAXSZ,
  	},
  	[OP_CB_RECALL_ANY] = {
  		.process_op = nfs4_callback_recallany,
  		.decode_args = decode_recallany_args,
  		.res_maxsize = CB_OP_RECALLANY_RES_MAXSZ,
  	},
  	[OP_CB_RECALL_SLOT] = {
  		.process_op = nfs4_callback_recallslot,
  		.decode_args = decode_recallslot_args,
  		.res_maxsize = CB_OP_RECALLSLOT_RES_MAXSZ,
  	},
  	[OP_CB_NOTIFY_LOCK] = {
  		.process_op = nfs4_callback_notify_lock,
  		.decode_args = decode_notify_lock_args,
  		.res_maxsize = CB_OP_NOTIFY_LOCK_RES_MAXSZ,
  	},
  #endif /* CONFIG_NFS_V4_1 */
  #ifdef CONFIG_NFS_V4_2
  	[OP_CB_OFFLOAD] = {
  		.process_op = nfs4_callback_offload,
  		.decode_args = decode_offload_args,
  		.res_maxsize = CB_OP_OFFLOAD_RES_MAXSZ,
  	},
  #endif /* CONFIG_NFS_V4_2 */
  };
  
  /*
   * Define NFS4 callback procedures
   */
  static const struct svc_procedure nfs4_callback_procedures1[] = {
  	[CB_NULL] = {
  		.pc_func = nfs4_callback_null,
  		.pc_decode = nfs4_decode_void,
  		.pc_encode = nfs4_encode_void,
  		.pc_xdrressize = 1,
  	},
  	[CB_COMPOUND] = {
  		.pc_func = nfs4_callback_compound,
  		.pc_encode = nfs4_encode_void,
  		.pc_argsize = 256,
  		.pc_ressize = 256,
  		.pc_xdrressize = NFS4_CALLBACK_BUFSIZE,
  	}
  };
  
  static unsigned int nfs4_callback_count1[ARRAY_SIZE(nfs4_callback_procedures1)];
  const struct svc_version nfs4_callback_version1 = {
  	.vs_vers = 1,
  	.vs_nproc = ARRAY_SIZE(nfs4_callback_procedures1),
  	.vs_proc = nfs4_callback_procedures1,
  	.vs_count = nfs4_callback_count1,
  	.vs_xdrsize = NFS4_CALLBACK_XDRSIZE,
  	.vs_dispatch = NULL,
  	.vs_hidden = true,
  	.vs_need_cong_ctrl = true,
  };
  
  static unsigned int nfs4_callback_count4[ARRAY_SIZE(nfs4_callback_procedures1)];
  const struct svc_version nfs4_callback_version4 = {
  	.vs_vers = 4,
  	.vs_nproc = ARRAY_SIZE(nfs4_callback_procedures1),
  	.vs_proc = nfs4_callback_procedures1,
  	.vs_count = nfs4_callback_count4,
  	.vs_xdrsize = NFS4_CALLBACK_XDRSIZE,
  	.vs_dispatch = NULL,
  	.vs_hidden = true,
  	.vs_need_cong_ctrl = true,
  };
  