// 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"

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


/*
 * Basic NFSv2 data types (RFC 1094 Section 2.3)
 */

/**
 * svcxdr_encode_stat - Encode an NFSv2 status code
 * @xdr: XDR stream
 * @status: status value to encode
 *
 * Return values:
 *   %false: Send buffer space was exhausted
 *   %true: Success
 */
bool
svcxdr_encode_stat(struct xdr_stream *xdr, __be32 status)
{
        __be32 *p;

        p = xdr_reserve_space(xdr, sizeof(status));
        if (!p)
                return false;
        *p = status;

        return true;
}

/**
 * svcxdr_decode_fhandle - Decode an NFSv2 file handle
 * @xdr: XDR stream positioned at an encoded NFSv2 FH
 * @fhp: OUT: filled-in server file handle
 *
 * Return values:
 *  %false: The encoded file handle was not valid
 *  %true: @fhp has been initialized
 */
bool
svcxdr_decode_fhandle(struct xdr_stream *xdr, struct svc_fh *fhp)
{
        __be32 *p;

        p = xdr_inline_decode(xdr, NFS_FHSIZE);
        if (!p)
                return false;
        fh_init(fhp, NFS_FHSIZE);
        memcpy(&fhp->fh_handle.fh_base, p, NFS_FHSIZE);
        fhp->fh_handle.fh_size = NFS_FHSIZE;

        return true;
}

static bool
svcxdr_encode_fhandle(struct xdr_stream *xdr, const struct svc_fh *fhp)
{
        __be32 *p;

        p = xdr_reserve_space(xdr, NFS_FHSIZE);
        if (!p)
                return false;
        memcpy(p, &fhp->fh_handle.fh_base, NFS_FHSIZE);

        return true;
}

static __be32 *
encode_timeval(__be32 *p, const struct timespec64 *time)
{
        *p++ = cpu_to_be32((u32)time->tv_sec);
        if (time->tv_nsec)
                *p++ = cpu_to_be32(time->tv_nsec / NSEC_PER_USEC);
        else
                *p++ = xdr_zero;
        return p;
}

static bool
svcxdr_decode_filename(struct xdr_stream *xdr, char **name, unsigned int *len)
{
        u32 size, i;
        __be32 *p;
        char *c;

        if (xdr_stream_decode_u32(xdr, &size) < 0)
                return false;
        if (size == 0 || size > NFS_MAXNAMLEN)
                return false;
        p = xdr_inline_decode(xdr, size);
        if (!p)
                return false;

        *len = size;
        *name = (char *)p;
        for (i = 0, c = *name; i < size; i++, c++)
                if (*c == '\0' || *c == '/')
                        return false;

        return true;
}

static bool
svcxdr_decode_diropargs(struct xdr_stream *xdr, struct svc_fh *fhp,
                        char **name, unsigned int *len)
{
        return svcxdr_decode_fhandle(xdr, fhp) &&
                svcxdr_decode_filename(xdr, name, len);
}

static bool
svcxdr_decode_sattr(struct svc_rqst *rqstp, struct xdr_stream *xdr,
                    struct iattr *iap)
{
        u32 tmp1, tmp2;
        __be32 *p;

        p = xdr_inline_decode(xdr, XDR_UNIT * 8);
        if (!p)
                return false;

        iap->ia_valid = 0;

        /*
         * Some Sun clients put 0xffff in the mode field when they
         * mean 0xffffffff.
         */
        tmp1 = be32_to_cpup(p++);
        if (tmp1 != (u32)-1 && tmp1 != 0xffff) {
                iap->ia_valid |= ATTR_MODE;
                iap->ia_mode = tmp1;
        }

        tmp1 = be32_to_cpup(p++);
        if (tmp1 != (u32)-1) {
                iap->ia_uid = make_kuid(nfsd_user_namespace(rqstp), tmp1);
                if (uid_valid(iap->ia_uid))
                        iap->ia_valid |= ATTR_UID;
        }

        tmp1 = be32_to_cpup(p++);
        if (tmp1 != (u32)-1) {
                iap->ia_gid = make_kgid(nfsd_user_namespace(rqstp), tmp1);
                if (gid_valid(iap->ia_gid))
                        iap->ia_valid |= ATTR_GID;
        }

        tmp1 = be32_to_cpup(p++);
        if (tmp1 != (u32)-1) {
                iap->ia_valid |= ATTR_SIZE;
                iap->ia_size = tmp1;
        }

        tmp1 = be32_to_cpup(p++);
        tmp2 = be32_to_cpup(p++);
        if (tmp1 != (u32)-1 && tmp2 != (u32)-1) {
                iap->ia_valid |= ATTR_ATIME | ATTR_ATIME_SET;
                iap->ia_atime.tv_sec = tmp1;
                iap->ia_atime.tv_nsec = tmp2 * NSEC_PER_USEC;
        }

        tmp1 = be32_to_cpup(p++);
        tmp2 = be32_to_cpup(p++);
        if (tmp1 != (u32)-1 && tmp2 != (u32)-1) {
                iap->ia_valid |= ATTR_MTIME | ATTR_MTIME_SET;
                iap->ia_mtime.tv_sec = tmp1;
                iap->ia_mtime.tv_nsec = tmp2 * NSEC_PER_USEC;
                /*
                 * 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 (tmp2 == 1000000)
                        iap->ia_valid &= ~(ATTR_ATIME_SET|ATTR_MTIME_SET);
        }

        return true;
}

/**
 * svcxdr_encode_fattr - Encode NFSv2 file attributes
 * @rqstp: Context of a completed RPC transaction
 * @xdr: XDR stream
 * @fhp: File handle to encode
 * @stat: Attributes to encode
 *
 * Return values:
 *   %false: Send buffer space was exhausted
 *   %true: Success
 */
bool
svcxdr_encode_fattr(struct svc_rqst *rqstp, struct xdr_stream *xdr,
                    const struct svc_fh *fhp, const struct kstat *stat)
{
        struct user_namespace *userns = nfsd_user_namespace(rqstp);
        struct dentry *dentry = fhp->fh_dentry;
        int type = stat->mode & S_IFMT;
        struct timespec64 time;
        __be32 *p;
        u32 fsid;

        p = xdr_reserve_space(xdr, XDR_UNIT * 17);
        if (!p)
                return false;

        *p++ = cpu_to_be32(nfs_ftypes[type >> 12]);
        *p++ = cpu_to_be32((u32)stat->mode);
        *p++ = cpu_to_be32((u32)stat->nlink);
        *p++ = cpu_to_be32((u32)from_kuid_munged(userns, stat->uid));
        *p++ = cpu_to_be32((u32)from_kgid_munged(userns, stat->gid));

        if (S_ISLNK(type) && stat->size > NFS_MAXPATHLEN)
                *p++ = cpu_to_be32(NFS_MAXPATHLEN);
        else
                *p++ = cpu_to_be32((u32) stat->size);
        *p++ = cpu_to_be32((u32) stat->blksize);
        if (S_ISCHR(type) || S_ISBLK(type))
                *p++ = cpu_to_be32(new_encode_dev(stat->rdev));
        else
                *p++ = cpu_to_be32(0xffffffff);
        *p++ = cpu_to_be32((u32)stat->blocks);

        switch (fsid_source(fhp)) {
        case FSIDSOURCE_FSID:
                fsid = (u32)fhp->fh_export->ex_fsid;
                break;
        case FSIDSOURCE_UUID:
                fsid = ((u32 *)fhp->fh_export->ex_uuid)[0];
                fsid ^= ((u32 *)fhp->fh_export->ex_uuid)[1];
                fsid ^= ((u32 *)fhp->fh_export->ex_uuid)[2];
                fsid ^= ((u32 *)fhp->fh_export->ex_uuid)[3];
                break;
        default:
                fsid = new_encode_dev(stat->dev);
                break;
        }
        *p++ = cpu_to_be32(fsid);

        *p++ = cpu_to_be32((u32)stat->ino);
        p = encode_timeval(p, &stat->atime);
        time = stat->mtime;
        lease_get_mtime(d_inode(dentry), &time);
        p = encode_timeval(p, &time);
        encode_timeval(p, &stat->ctime);

        return true;
}

/*
 * XDR decode functions
 */

int
nfssvc_decode_fhandleargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        struct nfsd_fhandle *args = rqstp->rq_argp;

        return svcxdr_decode_fhandle(xdr, &args->fh);
}

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

        return svcxdr_decode_fhandle(xdr, &args->fh) &&
                svcxdr_decode_sattr(rqstp, xdr, &args->attrs);
}

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

        return svcxdr_decode_diropargs(xdr, &args->fh, &args->name, &args->len);
}

int
nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        struct nfsd_readargs *args = rqstp->rq_argp;
        u32 totalcount;

        if (!svcxdr_decode_fhandle(xdr, &args->fh))
                return 0;
        if (xdr_stream_decode_u32(xdr, &args->offset) < 0)
                return 0;
        if (xdr_stream_decode_u32(xdr, &args->count) < 0)
                return 0;
        /* totalcount is ignored */
        if (xdr_stream_decode_u32(xdr, &totalcount) < 0)
                return 0;

        return 1;
}

int
nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        struct nfsd_writeargs *args = rqstp->rq_argp;
        struct kvec *head = rqstp->rq_arg.head;
        struct kvec *tail = rqstp->rq_arg.tail;
        u32 beginoffset, totalcount;
        size_t remaining;

        if (!svcxdr_decode_fhandle(xdr, &args->fh))
                return 0;
        /* beginoffset is ignored */
        if (xdr_stream_decode_u32(xdr, &beginoffset) < 0)
                return 0;
        if (xdr_stream_decode_u32(xdr, &args->offset) < 0)
                return 0;
        /* totalcount is ignored */
        if (xdr_stream_decode_u32(xdr, &totalcount) < 0)
                return 0;

        /* opaque data */
        if (xdr_stream_decode_u32(xdr, &args->len) < 0)
                return 0;
        if (args->len > NFSSVC_MAXBLKSIZE_V2)
                return 0;
        remaining = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len;
        remaining -= xdr_stream_pos(xdr);
        if (remaining < xdr_align_size(args->len))
                return 0;
        args->first.iov_base = xdr->p;
        args->first.iov_len = head->iov_len - xdr_stream_pos(xdr);

        return 1;
}

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

        return svcxdr_decode_diropargs(xdr, &args->fh,
                                       &args->name, &args->len) &&
                svcxdr_decode_sattr(rqstp, xdr, &args->attrs);
}

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

        return svcxdr_decode_diropargs(xdr, &args->ffh,
                                       &args->fname, &args->flen) &&
                svcxdr_decode_diropargs(xdr, &args->tfh,
                                        &args->tname, &args->tlen);
}

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

        return svcxdr_decode_fhandle(xdr, &args->ffh) &&
                svcxdr_decode_diropargs(xdr, &args->tfh,
                                        &args->tname, &args->tlen);
}

int
nfssvc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        struct nfsd_symlinkargs *args = rqstp->rq_argp;
        struct kvec *head = rqstp->rq_arg.head;

        if (!svcxdr_decode_diropargs(xdr, &args->ffh, &args->fname, &args->flen))
                return 0;
        if (xdr_stream_decode_u32(xdr, &args->tlen) < 0)
                return 0;
        if (args->tlen == 0)
                return 0;

        args->first.iov_len = head->iov_len - xdr_stream_pos(xdr);
        args->first.iov_base = xdr_inline_decode(xdr, args->tlen);
        if (!args->first.iov_base)
                return 0;
        return svcxdr_decode_sattr(rqstp, xdr, &args->attrs);
}

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

        if (!svcxdr_decode_fhandle(xdr, &args->fh))
                return 0;
        if (xdr_stream_decode_u32(xdr, &args->cookie) < 0)
                return 0;
        if (xdr_stream_decode_u32(xdr, &args->count) < 0)
                return 0;

        return 1;
}

/*
 * XDR encode functions
 */

int
nfssvc_encode_statres(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct nfsd_stat *resp = rqstp->rq_resp;

        return svcxdr_encode_stat(xdr, resp->status);
}

int
nfssvc_encode_attrstatres(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct nfsd_attrstat *resp = rqstp->rq_resp;

        if (!svcxdr_encode_stat(xdr, resp->status))
                return 0;
        switch (resp->status) {
        case nfs_ok:
                if (!svcxdr_encode_fattr(rqstp, xdr, &resp->fh, &resp->stat))
                        return 0;
                break;
        }

        return 1;
}

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

        if (!svcxdr_encode_stat(xdr, resp->status))
                return 0;
        switch (resp->status) {
        case nfs_ok:
                if (!svcxdr_encode_fhandle(xdr, &resp->fh))
                        return 0;
                if (!svcxdr_encode_fattr(rqstp, xdr, &resp->fh, &resp->stat))
                        return 0;
                break;
        }

        return 1;
}

int
nfssvc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct nfsd_readlinkres *resp = rqstp->rq_resp;
        struct kvec *head = rqstp->rq_res.head;

        if (!svcxdr_encode_stat(xdr, resp->status))
                return 0;
        switch (resp->status) {
        case nfs_ok:
                if (xdr_stream_encode_u32(xdr, resp->len) < 0)
                        return 0;
                xdr_write_pages(xdr, &resp->page, 0, resp->len);
                if (svc_encode_result_payload(rqstp, head->iov_len, resp->len) < 0)
                        return 0;
                break;
        }

        return 1;
}

int
nfssvc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct nfsd_readres *resp = rqstp->rq_resp;
        struct kvec *head = rqstp->rq_res.head;

        if (!svcxdr_encode_stat(xdr, resp->status))
                return 0;
        switch (resp->status) {
        case nfs_ok:
                if (!svcxdr_encode_fattr(rqstp, xdr, &resp->fh, &resp->stat))
                        return 0;
                if (xdr_stream_encode_u32(xdr, resp->count) < 0)
                        return 0;
                xdr_write_pages(xdr, resp->pages, rqstp->rq_res.page_base,
                                resp->count);
                if (svc_encode_result_payload(rqstp, head->iov_len, resp->count) < 0)
                        return 0;
                break;
        }

        return 1;
}

int
nfssvc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct nfsd_readdirres *resp = rqstp->rq_resp;
        struct xdr_buf *dirlist = &resp->dirlist;

        if (!svcxdr_encode_stat(xdr, resp->status))
                return 0;
        switch (resp->status) {
        case nfs_ok:
                xdr_write_pages(xdr, dirlist->pages, 0, dirlist->len);
                /* no more entries */
                if (xdr_stream_encode_item_absent(xdr) < 0)
                        return 0;
                if (xdr_stream_encode_bool(xdr, resp->common.err == nfserr_eof) < 0)
                        return 0;
                break;
        }

        return 1;
}

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

        if (!svcxdr_encode_stat(xdr, resp->status))
                return 0;
        switch (resp->status) {
        case nfs_ok:
                p = xdr_reserve_space(xdr, XDR_UNIT * 5);
                if (!p)
                        return 0;
                *p++ = cpu_to_be32(NFSSVC_MAXBLKSIZE_V2);
                *p++ = cpu_to_be32(stat->f_bsize);
                *p++ = cpu_to_be32(stat->f_blocks);
                *p++ = cpu_to_be32(stat->f_bfree);
                *p = cpu_to_be32(stat->f_bavail);
                break;
        }

        return 1;
}

/**
 * nfssvc_encode_nfscookie - Encode a directory offset cookie
 * @resp: readdir result context
 * @offset: offset cookie to encode
 *
 * The buffer space for the offset cookie has already been reserved
 * by svcxdr_encode_entry_common().
 */
void nfssvc_encode_nfscookie(struct nfsd_readdirres *resp, u32 offset)
{
        __be32 cookie = cpu_to_be32(offset);

        if (!resp->cookie_offset)
                return;

        write_bytes_to_xdr_buf(&resp->dirlist, resp->cookie_offset, &cookie,
                               sizeof(cookie));
        resp->cookie_offset = 0;
}

static bool
svcxdr_encode_entry_common(struct nfsd_readdirres *resp, const char *name,
                           int namlen, loff_t offset, u64 ino)
{
        struct xdr_buf *dirlist = &resp->dirlist;
        struct xdr_stream *xdr = &resp->xdr;

        if (xdr_stream_encode_item_present(xdr) < 0)
                return false;
        /* fileid */
        if (xdr_stream_encode_u32(xdr, (u32)ino) < 0)
                return false;
        /* name */
        if (xdr_stream_encode_opaque(xdr, name, min(namlen, NFS2_MAXNAMLEN)) < 0)
                return false;
        /* cookie */
        resp->cookie_offset = dirlist->len;
        if (xdr_stream_encode_u32(xdr, ~0U) < 0)
                return false;

        return true;
}

/**
 * nfssvc_encode_entry - encode one NFSv2 READDIR entry
 * @data: directory context
 * @name: name of the object to be encoded
 * @namlen: length of that name, in bytes
 * @offset: the offset of the previous entry
 * @ino: the fileid of this entry
 * @d_type: unused
 *
 * Return values:
 *   %0: Entry was successfully encoded.
 *   %-EINVAL: An encoding problem occured, secondary status code in resp->common.err
 *
 * On exit, the following fields are updated:
 *   - resp->xdr
 *   - resp->common.err
 *   - resp->cookie_offset
 */
int nfssvc_encode_entry(void *data, const char *name, int namlen,
                        loff_t offset, u64 ino, unsigned int d_type)
{
        struct readdir_cd *ccd = data;
        struct nfsd_readdirres *resp = container_of(ccd,
                                                    struct nfsd_readdirres,
                                                    common);
        unsigned int starting_length = resp->dirlist.len;

        /* The offset cookie for the previous entry */
        nfssvc_encode_nfscookie(resp, offset);

        if (!svcxdr_encode_entry_common(resp, name, namlen, offset, ino))
                goto out_toosmall;

        xdr_commit_encode(&resp->xdr);
        resp->common.err = nfs_ok;
        return 0;

out_toosmall:
        resp->cookie_offset = 0;
        resp->common.err = nfserr_toosmall;
        resp->dirlist.len = starting_length;
        return -EINVAL;
}

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

        fh_put(&resp->fh);
}

void nfssvc_release_diropres(struct svc_rqst *rqstp)
{
        struct nfsd_diropres *resp = rqstp->rq_resp;

        fh_put(&resp->fh);
}

void nfssvc_release_readres(struct svc_rqst *rqstp)
{
        struct nfsd_readres *resp = rqstp->rq_resp;

        fh_put(&resp->fh);
}