// 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"
#include "nfs4trace.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, atime, ctime,
                                          * mtime, deleg_atime, deleg_mtime */\
                                         (2 + 2 + 3 + 3 + 3 + 3 + 3) * 4)
#define CB_OP_RECALL_RES_MAXSZ          (CB_OP_HDR_RES_MAXSZ)

#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)
#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);
}

/*
 * svc_process_common() looks for an XDR encoder to know when
 * not to drop a Reply.
 */
static bool nfs4_encode_void(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
        return true;
}

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++);
        if (attrlen > 2)
                bitmap[2] = 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);
}

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;
        uint32_t tmp, n, i;
        __be32 *p;
        __be32 status = 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;

        args->devs = kmalloc_objs(*args->devs, n);
        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;
                }

                dprintk("%s: type %d layout 0x%x immediate %d\n",
                        __func__, dev->cbd_notify_type, dev->cbd_layout_type,
                        dev->cbd_immediate);
        }
        args->ndevs = n;
        dprintk("%s: ndevs %d\n", __func__, args->ndevs);
        return 0;
err:
        kfree(args->devs);
out:
        args->devs = NULL;
        args->ndevs = 0;
        dprintk("%s: status %d ndevs %d\n",
                __func__, ntohl(status), args->ndevs);
        return status;
}

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) {
                if (unlikely(rc_list->rcl_nrefcalls > xdr->buf->len))
                        goto out;
                p = xdr_inline_decode(xdr,
                             rc_list->rcl_nrefcalls * 2 * sizeof(uint32_t));
                if (unlikely(p == NULL))
                        goto out;
                rc_list->rcl_refcalls = kmalloc_objs(*rc_list->rcl_refcalls,
                                                     rc_list->rcl_nrefcalls);
                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_objs(*args->csa_rclists,
                                                 args->csa_nrclists);
                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[3];
        __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);
}

#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 timespec64 *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_atime(struct xdr_stream *xdr, const uint32_t *bitmap, const struct timespec64 *time)
{
        if (!(bitmap[1] & FATTR4_WORD1_TIME_ACCESS))
                return 0;
        return encode_attr_time(xdr,time);
}

static __be32 encode_attr_ctime(struct xdr_stream *xdr, const uint32_t *bitmap, const struct timespec64 *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 timespec64 *time)
{
        if (!(bitmap[1] & FATTR4_WORD1_TIME_MODIFY))
                return 0;
        return encode_attr_time(xdr,time);
}

static __be32 encode_attr_delegatime(struct xdr_stream *xdr,
                                     const uint32_t *bitmap,
                                     const struct timespec64 *time)
{
        if (!(bitmap[2] & FATTR4_WORD2_TIME_DELEG_ACCESS))
                return 0;
        return encode_attr_time(xdr,time);
}

static __be32 encode_attr_delegmtime(struct xdr_stream *xdr,
                                     const uint32_t *bitmap,
                                     const struct timespec64 *time)
{
        if (!(bitmap[2] & FATTR4_WORD2_TIME_DELEG_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_atime(xdr, res->bitmap, &res->atime);
        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);
        if (unlikely(status != 0))
                goto out;
        status = encode_attr_delegatime(xdr, res->bitmap, &res->atime);
        if (unlikely(status != 0))
                goto out;
        status = encode_attr_delegmtime(xdr, res->bitmap, &res->mtime);
        *savep = htonl((unsigned int)((char *)xdr->p - (char *)(savep+1)));
out:
        return status;
}

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;
        }
}

#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 cb_process_state *cps)
{
        struct xdr_stream *xdr_out = &rqstp->rq_res_stream;
        struct callback_op *op = &callback_ops[0];
        unsigned int op_nr;
        __be32 status;
        long maxlen;
        __be32 res;

        status = decode_op_hdr(&rqstp->rq_arg_stream, &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, &rqstp->rq_arg_stream,
                                         rqstp->rq_argp);
                if (likely(status == 0))
                        status = op->process_op(rqstp->rq_argp, rqstp->rq_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, rqstp->rq_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 cb_process_state cps = {
                .drc_status = 0,
                .clp = NULL,
                .net = SVC_NET(rqstp),
        };
        unsigned int nops = 0;
        __be32 status;

        status = decode_compound_hdr_arg(&rqstp->rq_arg_stream, &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) {
                        trace_nfs_cb_no_clp(rqstp->rq_xid, hdr_arg.cb_ident);
                        goto out_invalidcred;
                }
                if (!check_gss_callback_principal(cps.clp, rqstp)) {
                        trace_nfs_cb_badprinc(rqstp->rq_xid, hdr_arg.cb_ident);
                        nfs_put_client(cps.clp);
                        goto out_invalidcred;
                }
                svc_xprt_set_valid(rqstp->rq_xprt);
        }

        cps.minorversion = hdr_arg.minorversion;
        hdr_res.taglen = hdr_arg.taglen;
        hdr_res.tag = hdr_arg.tag;
        if (encode_compound_hdr_res(&rqstp->rq_res_stream, &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, &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--;
        }

        if (svc_is_backchannel(rqstp) && cps.clp) {
                rqstp->bc_to_initval = cps.clp->cl_rpcclient->cl_timeout->to_initval;
                rqstp->bc_to_retries = cps.clp->cl_rpcclient->cl_timeout->to_retries;
        }

        *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");
        rqstp->rq_auth_stat = rpc_autherr_badcred;
        return rpc_success;
}

static int
nfs_callback_dispatch(struct svc_rqst *rqstp)
{
        const struct svc_procedure *procp = rqstp->rq_procinfo;

        *rqstp->rq_accept_statp = procp->pc_func(rqstp);
        return 1;
}

/*
 * 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,
        },
        [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,
        },
#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_encode = nfs4_encode_void,
                .pc_xdrressize = 1,
                .pc_name = "NULL",
        },
        [CB_COMPOUND] = {
                .pc_func = nfs4_callback_compound,
                .pc_encode = nfs4_encode_void,
                .pc_argsize = 256,
                .pc_argzero = 256,
                .pc_ressize = 256,
                .pc_xdrressize = NFS4_CALLBACK_BUFSIZE,
                .pc_name = "COMPOUND",
        }
};

static DEFINE_PER_CPU_ALIGNED(unsigned long,
                              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 = nfs_callback_dispatch,
        .vs_hidden = true,
        .vs_need_cong_ctrl = true,
};

static DEFINE_PER_CPU_ALIGNED(unsigned long,
                              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 = nfs_callback_dispatch,
        .vs_hidden = true,
        .vs_need_cong_ctrl = true,
};