svcshare.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * linux/fs/lockd/svcshare.c
  4 *
  5 * Management of DOS shares.
  6 *
  7 * Copyright (C) 1996 Olaf Kirch <okir@monad.swb.de>
  8 */
  9
 10#include <linux/time.h>
 11#include <linux/unistd.h>
 12#include <linux/string.h>
 13#include <linux/slab.h>
 14
 15#include <linux/sunrpc/clnt.h>
 16#include <linux/sunrpc/svc.h>
 17#include <linux/lockd/lockd.h>
 18#include <linux/lockd/share.h>
 19
 20static inline int
 21nlm_cmp_owner(struct nlm_share *share, struct xdr_netobj *oh)
 22{
 23	return share->s_owner.len == oh->len
 24	    && !memcmp(share->s_owner.data, oh->data, oh->len);
 25}
 26
 27__be32
 28nlmsvc_share_file(struct nlm_host *host, struct nlm_file *file,
 29			struct nlm_args *argp)
 30{
 31	struct nlm_share	*share;
 32	struct xdr_netobj	*oh = &argp->lock.oh;
 33	u8			*ohdata;
 34
 35	if (nlmsvc_file_cannot_lock(file))
 36		return nlm_lck_denied_nolocks;
 37
 38	for (share = file->f_shares; share; share = share->s_next) {
 39		if (share->s_host == host && nlm_cmp_owner(share, oh))
 40			goto update;
 41		if ((argp->fsm_access & share->s_mode)
 42		 || (argp->fsm_mode   & share->s_access ))
 43			return nlm_lck_denied;
 44	}
 45
 46	share = kmalloc(sizeof(*share) + oh->len,
 47						GFP_KERNEL);
 48	if (share == NULL)
 49		return nlm_lck_denied_nolocks;
 50
 51	/* Copy owner handle */
 52	ohdata = (u8 *) (share + 1);
 53	memcpy(ohdata, oh->data, oh->len);
 54
 55	share->s_file	    = file;
 56	share->s_host       = host;
 57	share->s_owner.data = ohdata;
 58	share->s_owner.len  = oh->len;
 59	share->s_next       = file->f_shares;
 60	file->f_shares      = share;
 61
 62update:
 63	share->s_access = argp->fsm_access;
 64	share->s_mode   = argp->fsm_mode;
 65	return nlm_granted;
 66}
 67
 68/*
 69 * Delete a share.
 70 */
 71__be32
 72nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
 73			struct nlm_args *argp)
 74{
 75	struct nlm_share	*share, **shpp;
 76	struct xdr_netobj	*oh = &argp->lock.oh;
 77
 78	if (nlmsvc_file_cannot_lock(file))
 79		return nlm_lck_denied_nolocks;
 80
 81	for (shpp = &file->f_shares; (share = *shpp) != NULL;
 82					shpp = &share->s_next) {
 83		if (share->s_host == host && nlm_cmp_owner(share, oh)) {
 84			*shpp = share->s_next;
 85			kfree(share);
 86			return nlm_granted;
 87		}
 88	}
 89
 90	/* X/Open spec says return success even if there was no
 91	 * corresponding share. */
 92	return nlm_granted;
 93}
 94
 95/*
 96 * Traverse all shares for a given file, and delete
 97 * those owned by the given (type of) host
 98 */
 99void nlmsvc_traverse_shares(struct nlm_host *host, struct nlm_file *file,
100		nlm_host_match_fn_t match)
101{
102	struct nlm_share	*share, **shpp;
103
104	shpp = &file->f_shares;
105	while ((share = *shpp) !=  NULL) {
106		if (match(share->s_host, host)) {
107			*shpp = share->s_next;
108			kfree(share);
109			continue;
110		}
111		shpp = &share->s_next;
112	}
113}