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// 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);
}
/*
* Recompute s_access / s_mode as the union of every (access, deny) pair
* whose bit is currently set in s_access_deny_bmap.
*/
static void nlm_recompute_share(struct lockd_share *share)
{
u32 new_access = 0, new_mode = 0;
unsigned int i;
for (i = 0; i < 16; i++) {
if (share->s_access_deny_bmap & BIT(i)) {
new_access |= i >> 2;
new_mode |= i & 3;
}
}
share->s_access = new_access;
share->s_mode = new_mode;
}
/**
* 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_access_deny_bmap = 0;
share->s_next = file->f_shares;
file->f_shares = share;
update:
share->s_access_deny_bmap |= LOCKD_FSH_BIT(access, mode);
nlm_recompute_share(share);
return nlm_granted;
}
/**
* nlmsvc_unshare_file - delete a share
* @host: Network client peer
* @file: File to be unshared
* @oh: Share owner handle
* @access: Access mode of the SHARE being released
* @mode: Deny mode of the SHARE being released
*
* Returns an NLM status code.
*/
__be32
nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
struct xdr_netobj *oh, u32 access, u32 mode)
{
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)) {
share->s_access_deny_bmap &= ~LOCKD_FSH_BIT(access, mode);
nlm_recompute_share(share);
if (!share->s_access_deny_bmap) {
*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;
}
}
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