// SPDX-License-Identifier: GPL-2.0
/*
 * XDR support for nfsd
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include "vfs.h"
#include "xdr.h"
#include "auth.h"

#define NFSDDBG_FACILITY                NFSDDBG_XDR

/*
 * Mapping of S_IF* types to NFS file types
 */
static u32      nfs_ftypes[] = {
        NFNON,  NFCHR,  NFCHR, NFBAD,
        NFDIR,  NFBAD,  NFBLK, NFBAD,
        NFREG,  NFBAD,  NFLNK, NFBAD,
        NFSOCK, NFBAD,  NFLNK, NFBAD,
};


/*
 * XDR functions for basic NFS types
 */
static __be32 *
decode_fh(__be32 *p, struct svc_fh *fhp)
{
        fh_init(fhp, NFS_FHSIZE);
        memcpy(&fhp->fh_handle.fh_base, p, NFS_FHSIZE);
        fhp->fh_handle.fh_size = NFS_FHSIZE;

        /* FIXME: Look up export pointer here and verify
         * Sun Secure RPC if requested */
        return p + (NFS_FHSIZE >> 2);
}

/* Helper function for NFSv2 ACL code */
__be32 *nfs2svc_decode_fh(__be32 *p, struct svc_fh *fhp)
{
        return decode_fh(p, fhp);
}

static __be32 *
encode_fh(__be32 *p, struct svc_fh *fhp)
{
        memcpy(p, &fhp->fh_handle.fh_base, NFS_FHSIZE);
        return p + (NFS_FHSIZE>> 2);
}

/*
 * Decode a file name and make sure that the path contains
 * no slashes or null bytes.
 */
static __be32 *
decode_filename(__be32 *p, char **namp, unsigned int *lenp)
{
        char            *name;
        unsigned int    i;

        if ((p = xdr_decode_string_inplace(p, namp, lenp, NFS_MAXNAMLEN)) != NULL) {
                for (i = 0, name = *namp; i < *lenp; i++, name++) {
                        if (*name == '\0' || *name == '/')
                                return NULL;
                }
        }

        return p;
}

static __be32 *
decode_sattr(__be32 *p, struct iattr *iap, struct user_namespace *userns)
{
        u32     tmp, tmp1;

        iap->ia_valid = 0;

        /* Sun client bug compatibility check: some sun clients seem to
         * put 0xffff in the mode field when they mean 0xffffffff.
         * Quoting the 4.4BSD nfs server code: Nah nah nah nah na nah.
         */
        if ((tmp = ntohl(*p++)) != (u32)-1 && tmp != 0xffff) {
                iap->ia_valid |= ATTR_MODE;
                iap->ia_mode = tmp;
        }
        if ((tmp = ntohl(*p++)) != (u32)-1) {
                iap->ia_uid = make_kuid(userns, tmp);
                if (uid_valid(iap->ia_uid))
                        iap->ia_valid |= ATTR_UID;
        }
        if ((tmp = ntohl(*p++)) != (u32)-1) {
                iap->ia_gid = make_kgid(userns, tmp);
                if (gid_valid(iap->ia_gid))
                        iap->ia_valid |= ATTR_GID;
        }
        if ((tmp = ntohl(*p++)) != (u32)-1) {
                iap->ia_valid |= ATTR_SIZE;
                iap->ia_size = tmp;
        }
        tmp  = ntohl(*p++); tmp1 = ntohl(*p++);
        if (tmp != (u32)-1 && tmp1 != (u32)-1) {
                iap->ia_valid |= ATTR_ATIME | ATTR_ATIME_SET;
                iap->ia_atime.tv_sec = tmp;
                iap->ia_atime.tv_nsec = tmp1 * 1000; 
        }
        tmp  = ntohl(*p++); tmp1 = ntohl(*p++);
        if (tmp != (u32)-1 && tmp1 != (u32)-1) {
                iap->ia_valid |= ATTR_MTIME | ATTR_MTIME_SET;
                iap->ia_mtime.tv_sec = tmp;
                iap->ia_mtime.tv_nsec = tmp1 * 1000; 
                /*
                 * Passing the invalid value useconds=1000000 for mtime
                 * is a Sun convention for "set both mtime and atime to
                 * current server time".  It's needed to make permissions
                 * checks for the "touch" program across v2 mounts to
                 * Solaris and Irix boxes work correctly. See description of
                 * sattr in section 6.1 of "NFS Illustrated" by
                 * Brent Callaghan, Addison-Wesley, ISBN 0-201-32750-5
                 */
                if (tmp1 == 1000000)
                        iap->ia_valid &= ~(ATTR_ATIME_SET|ATTR_MTIME_SET);
        }
        return p;
}

static __be32 *
encode_fattr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp,
             struct kstat *stat)
{
        struct user_namespace *userns = nfsd_user_namespace(rqstp);
        struct dentry   *dentry = fhp->fh_dentry;
        int type;
        struct timespec64 time;
        u32 f;

        type = (stat->mode & S_IFMT);

        *p++ = htonl(nfs_ftypes[type >> 12]);
        *p++ = htonl((u32) stat->mode);
        *p++ = htonl((u32) stat->nlink);
        *p++ = htonl((u32) from_kuid_munged(userns, stat->uid));
        *p++ = htonl((u32) from_kgid_munged(userns, stat->gid));

        if (S_ISLNK(type) && stat->size > NFS_MAXPATHLEN) {
                *p++ = htonl(NFS_MAXPATHLEN);
        } else {
                *p++ = htonl((u32) stat->size);
        }
        *p++ = htonl((u32) stat->blksize);
        if (S_ISCHR(type) || S_ISBLK(type))
                *p++ = htonl(new_encode_dev(stat->rdev));
        else
                *p++ = htonl(0xffffffff);
        *p++ = htonl((u32) stat->blocks);
        switch (fsid_source(fhp)) {
        default:
        case FSIDSOURCE_DEV:
                *p++ = htonl(new_encode_dev(stat->dev));
                break;
        case FSIDSOURCE_FSID:
                *p++ = htonl((u32) fhp->fh_export->ex_fsid);
                break;
        case FSIDSOURCE_UUID:
                f = ((u32*)fhp->fh_export->ex_uuid)[0];
                f ^= ((u32*)fhp->fh_export->ex_uuid)[1];
                f ^= ((u32*)fhp->fh_export->ex_uuid)[2];
                f ^= ((u32*)fhp->fh_export->ex_uuid)[3];
                *p++ = htonl(f);
                break;
        }
        *p++ = htonl((u32) stat->ino);
        *p++ = htonl((u32) stat->atime.tv_sec);
        *p++ = htonl(stat->atime.tv_nsec ? stat->atime.tv_nsec / 1000 : 0);
        time = stat->mtime;
        lease_get_mtime(d_inode(dentry), &time); 
        *p++ = htonl((u32) time.tv_sec);
        *p++ = htonl(time.tv_nsec ? time.tv_nsec / 1000 : 0); 
        *p++ = htonl((u32) stat->ctime.tv_sec);
        *p++ = htonl(stat->ctime.tv_nsec ? stat->ctime.tv_nsec / 1000 : 0);

        return p;
}

/* Helper function for NFSv2 ACL code */
__be32 *nfs2svc_encode_fattr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp, struct kstat *stat)
{
        return encode_fattr(rqstp, p, fhp, stat);
}

/*
 * XDR decode functions
 */
int
nfssvc_decode_void(struct svc_rqst *rqstp, __be32 *p)
{
        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_fhandle(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_fhandle *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_sattrargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_sattrargs *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = decode_sattr(p, &args->attrs, nfsd_user_namespace(rqstp));

        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_diropargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_diropargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->fh))
         || !(p = decode_filename(p, &args->name, &args->len)))
                return 0;

        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_readargs *args = rqstp->rq_argp;
        unsigned int len;
        int v;
        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;

        args->offset    = ntohl(*p++);
        len = args->count     = ntohl(*p++);
        p++; /* totalcount - unused */

        len = min_t(unsigned int, len, NFSSVC_MAXBLKSIZE_V2);

        /* set up somewhere to store response.
         * We take pages, put them on reslist and include in iovec
         */
        v=0;
        while (len > 0) {
                struct page *p = *(rqstp->rq_next_page++);

                rqstp->rq_vec[v].iov_base = page_address(p);
                rqstp->rq_vec[v].iov_len = min_t(unsigned int, len, PAGE_SIZE);
                len -= rqstp->rq_vec[v].iov_len;
                v++;
        }
        args->vlen = v;
        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_writeargs *args = rqstp->rq_argp;
        unsigned int len, hdr, dlen;
        struct kvec *head = rqstp->rq_arg.head;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;

        p++;                            /* beginoffset */
        args->offset = ntohl(*p++);     /* offset */
        p++;                            /* totalcount */
        len = args->len = ntohl(*p++);
        /*
         * The protocol specifies a maximum of 8192 bytes.
         */
        if (len > NFSSVC_MAXBLKSIZE_V2)
                return 0;

        /*
         * Check to make sure that we got the right number of
         * bytes.
         */
        hdr = (void*)p - head->iov_base;
        if (hdr > head->iov_len)
                return 0;
        dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;

        /*
         * Round the length of the data which was specified up to
         * the next multiple of XDR units and then compare that
         * against the length which was actually received.
         * Note that when RPCSEC/GSS (for example) is used, the
         * data buffer can be padded so dlen might be larger
         * than required.  It must never be smaller.
         */
        if (dlen < XDR_QUADLEN(len)*4)
                return 0;

        args->first.iov_base = (void *)p;
        args->first.iov_len = head->iov_len - hdr;
        return 1;
}

int
nfssvc_decode_createargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_createargs *args = rqstp->rq_argp;

        if (   !(p = decode_fh(p, &args->fh))
            || !(p = decode_filename(p, &args->name, &args->len)))
                return 0;
        p = decode_sattr(p, &args->attrs, nfsd_user_namespace(rqstp));

        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_renameargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_renameargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->ffh))
         || !(p = decode_filename(p, &args->fname, &args->flen))
         || !(p = decode_fh(p, &args->tfh))
         || !(p = decode_filename(p, &args->tname, &args->tlen)))
                return 0;

        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_readlinkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_readlinkargs *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        args->buffer = page_address(*(rqstp->rq_next_page++));

        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_linkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_linkargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->ffh))
         || !(p = decode_fh(p, &args->tfh))
         || !(p = decode_filename(p, &args->tname, &args->tlen)))
                return 0;

        return xdr_argsize_check(rqstp, p);
}

int
nfssvc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_symlinkargs *args = rqstp->rq_argp;
        char *base = (char *)p;
        size_t xdrlen;

        if (   !(p = decode_fh(p, &args->ffh))
            || !(p = decode_filename(p, &args->fname, &args->flen)))
                return 0;

        args->tlen = ntohl(*p++);
        if (args->tlen == 0)
                return 0;

        args->first.iov_base = p;
        args->first.iov_len = rqstp->rq_arg.head[0].iov_len;
        args->first.iov_len -= (char *)p - base;

        /* This request is never larger than a page. Therefore,
         * transport will deliver either:
         * 1. pathname in the pagelist -> sattr is in the tail.
         * 2. everything in the head buffer -> sattr is in the head.
         */
        if (rqstp->rq_arg.page_len) {
                if (args->tlen != rqstp->rq_arg.page_len)
                        return 0;
                p = rqstp->rq_arg.tail[0].iov_base;
        } else {
                xdrlen = XDR_QUADLEN(args->tlen);
                if (xdrlen > args->first.iov_len - (8 * sizeof(__be32)))
                        return 0;
                p += xdrlen;
        }
        decode_sattr(p, &args->attrs, nfsd_user_namespace(rqstp));

        return 1;
}

int
nfssvc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_readdirargs *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        args->cookie = ntohl(*p++);
        args->count  = ntohl(*p++);
        args->count  = min_t(u32, args->count, PAGE_SIZE);
        args->buffer = page_address(*(rqstp->rq_next_page++));

        return xdr_argsize_check(rqstp, p);
}

/*
 * XDR encode functions
 */
int
nfssvc_encode_void(struct svc_rqst *rqstp, __be32 *p)
{
        return xdr_ressize_check(rqstp, p);
}

int
nfssvc_encode_attrstat(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_attrstat *resp = rqstp->rq_resp;

        p = encode_fattr(rqstp, p, &resp->fh, &resp->stat);
        return xdr_ressize_check(rqstp, p);
}

int
nfssvc_encode_diropres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_diropres *resp = rqstp->rq_resp;

        p = encode_fh(p, &resp->fh);
        p = encode_fattr(rqstp, p, &resp->fh, &resp->stat);
        return xdr_ressize_check(rqstp, p);
}

int
nfssvc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_readlinkres *resp = rqstp->rq_resp;

        *p++ = htonl(resp->len);
        xdr_ressize_check(rqstp, p);
        rqstp->rq_res.page_len = resp->len;
        if (resp->len & 3) {
                /* need to pad the tail */
                rqstp->rq_res.tail[0].iov_base = p;
                *p = 0;
                rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
        }
        return 1;
}

int
nfssvc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_readres *resp = rqstp->rq_resp;

        p = encode_fattr(rqstp, p, &resp->fh, &resp->stat);
        *p++ = htonl(resp->count);
        xdr_ressize_check(rqstp, p);

        /* now update rqstp->rq_res to reflect data as well */
        rqstp->rq_res.page_len = resp->count;
        if (resp->count & 3) {
                /* need to pad the tail */
                rqstp->rq_res.tail[0].iov_base = p;
                *p = 0;
                rqstp->rq_res.tail[0].iov_len = 4 - (resp->count&3);
        }
        return 1;
}

int
nfssvc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_readdirres *resp = rqstp->rq_resp;

        xdr_ressize_check(rqstp, p);
        p = resp->buffer;
        *p++ = 0;                       /* no more entries */
        *p++ = htonl((resp->common.err == nfserr_eof));
        rqstp->rq_res.page_len = (((unsigned long)p-1) & ~PAGE_MASK)+1;

        return 1;
}

int
nfssvc_encode_statfsres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_statfsres *resp = rqstp->rq_resp;
        struct kstatfs  *stat = &resp->stats;

        *p++ = htonl(NFSSVC_MAXBLKSIZE_V2);     /* max transfer size */
        *p++ = htonl(stat->f_bsize);
        *p++ = htonl(stat->f_blocks);
        *p++ = htonl(stat->f_bfree);
        *p++ = htonl(stat->f_bavail);
        return xdr_ressize_check(rqstp, p);
}

int
nfssvc_encode_entry(void *ccdv, const char *name,
                    int namlen, loff_t offset, u64 ino, unsigned int d_type)
{
        struct readdir_cd *ccd = ccdv;
        struct nfsd_readdirres *cd = container_of(ccd, struct nfsd_readdirres, common);
        __be32  *p = cd->buffer;
        int     buflen, slen;

        /*
        dprintk("nfsd: entry(%.*s off %ld ino %ld)\n",
                        namlen, name, offset, ino);
         */

        if (offset > ~((u32) 0)) {
                cd->common.err = nfserr_fbig;
                return -EINVAL;
        }
        if (cd->offset)
                *cd->offset = htonl(offset);

        /* truncate filename */
        namlen = min(namlen, NFS2_MAXNAMLEN);
        slen = XDR_QUADLEN(namlen);

        if ((buflen = cd->buflen - slen - 4) < 0) {
                cd->common.err = nfserr_toosmall;
                return -EINVAL;
        }
        if (ino > ~((u32) 0)) {
                cd->common.err = nfserr_fbig;
                return -EINVAL;
        }
        *p++ = xdr_one;                         /* mark entry present */
        *p++ = htonl((u32) ino);                /* file id */
        p    = xdr_encode_array(p, name, namlen);/* name length & name */
        cd->offset = p;                 /* remember pointer */
        *p++ = htonl(~0U);              /* offset of next entry */

        cd->buflen = buflen;
        cd->buffer = p;
        cd->common.err = nfs_ok;
        return 0;
}

/*
 * XDR release functions
 */
void
nfssvc_release_fhandle(struct svc_rqst *rqstp)
{
        struct nfsd_fhandle *resp = rqstp->rq_resp;

        fh_put(&resp->fh);
}