// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/lockd/svcshare.c
 *
 * Management of DOS shares.
 *
 * Copyright (C) 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/time.h>
#include <linux/unistd.h>
#include <linux/string.h>
#include <linux/slab.h>

#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>

#include "lockd.h"
#include "share.h"

static inline int
nlm_cmp_owner(struct lockd_share *share, struct xdr_netobj *oh)
{
        return share->s_owner.len == oh->len
            && !memcmp(share->s_owner.data, oh->data, oh->len);
}

/**
 * nlmsvc_share_file - create a share
 * @host: Network client peer
 * @file: File to be shared
 * @oh: Share owner handle
 * @access: Requested access mode
 * @mode: Requested file sharing mode
 *
 * Returns an NLM status code.
 */
__be32
nlmsvc_share_file(struct nlm_host *host, struct nlm_file *file,
                  struct xdr_netobj *oh, u32 access, u32 mode)
{
        struct lockd_share      *share;
        u8                      *ohdata;

        if (nlmsvc_file_cannot_lock(file))
                return nlm_lck_denied_nolocks;

        for (share = file->f_shares; share; share = share->s_next) {
                if (share->s_host == host && nlm_cmp_owner(share, oh))
                        goto update;
                if ((access & share->s_mode) || (mode & share->s_access))
                        return nlm_lck_denied;
        }

        share = kmalloc(sizeof(*share) + oh->len, GFP_KERNEL);
        if (share == NULL)
                return nlm_lck_denied_nolocks;

        /* Copy owner handle */
        ohdata = (u8 *) (share + 1);
        memcpy(ohdata, oh->data, oh->len);

        share->s_file       = file;
        share->s_host       = host;
        share->s_owner.data = ohdata;
        share->s_owner.len  = oh->len;
        share->s_next       = file->f_shares;
        file->f_shares      = share;

update:
        share->s_access = access;
        share->s_mode = mode;
        return nlm_granted;
}

/**
 * nlmsvc_unshare_file - delete a share
 * @host: Network client peer
 * @file: File to be unshared
 * @oh: Share owner handle
 *
 * Returns an NLM status code.
 */
__be32
nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
                    struct xdr_netobj *oh)
{
        struct lockd_share      *share, **shpp;

        if (nlmsvc_file_cannot_lock(file))
                return nlm_lck_denied_nolocks;

        for (shpp = &file->f_shares; (share = *shpp) != NULL;
                                        shpp = &share->s_next) {
                if (share->s_host == host && nlm_cmp_owner(share, oh)) {
                        *shpp = share->s_next;
                        kfree(share);
                        return nlm_granted;
                }
        }

        /* X/Open spec says return success even if there was no
         * corresponding share. */
        return nlm_granted;
}

/*
 * Traverse all shares for a given file, and delete
 * those owned by the given (type of) host
 */
void nlmsvc_traverse_shares(struct nlm_host *host, struct nlm_file *file,
                nlm_host_match_fn_t match)
{
        struct lockd_share      *share, **shpp;

        shpp = &file->f_shares;
        while ((share = *shpp) !=  NULL) {
                if (match(share->s_host, host)) {
                        *shpp = share->s_next;
                        kfree(share);
                        continue;
                }
                shpp = &share->s_next;
        }
}