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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 <[email protected]>
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
18#include "lockd.h"
19#include "share.h"
20
21static inline int
22nlm_cmp_owner(struct lockd_share *share, struct xdr_netobj *oh)
23{
24 return share->s_owner.len == oh->len
25 && !memcmp(share->s_owner.data, oh->data, oh->len);
26}
27
28/*
29 * Recompute s_access / s_mode as the union of every (access, deny) pair
30 * whose bit is currently set in s_access_deny_bmap.
31 */
32static void nlm_recompute_share(struct lockd_share *share)
33{
34 u32 new_access = 0, new_mode = 0;
35 unsigned int i;
36
37 for (i = 0; i < 16; i++) {
38 if (share->s_access_deny_bmap & BIT(i)) {
39 new_access |= i >> 2;
40 new_mode |= i & 3;
41 }
42 }
43 share->s_access = new_access;
44 share->s_mode = new_mode;
45}
46
47/**
48 * nlmsvc_share_file - create a share
49 * @host: Network client peer
50 * @file: File to be shared
51 * @oh: Share owner handle
52 * @access: Requested access mode
53 * @mode: Requested file sharing mode
54 *
55 * Returns an NLM status code.
56 */
57__be32
58nlmsvc_share_file(struct nlm_host *host, struct nlm_file *file,
59 struct xdr_netobj *oh, u32 access, u32 mode)
60{
61 struct lockd_share *share;
62 u8 *ohdata;
63
64 if (nlmsvc_file_cannot_lock(file))
65 return nlm_lck_denied_nolocks;
66
67 for (share = file->f_shares; share; share = share->s_next) {
68 if (share->s_host == host && nlm_cmp_owner(share, oh))
69 goto update;
70 if ((access & share->s_mode) || (mode & share->s_access))
71 return nlm_lck_denied;
72 }
73
74 share = kmalloc(sizeof(*share) + oh->len, GFP_KERNEL);
75 if (share == NULL)
76 return nlm_lck_denied_nolocks;
77
78 /* Copy owner handle */
79 ohdata = (u8 *) (share + 1);
80 memcpy(ohdata, oh->data, oh->len);
81
82 share->s_file = file;
83 share->s_host = host;
84 share->s_owner.data = ohdata;
85 share->s_owner.len = oh->len;
86 share->s_access_deny_bmap = 0;
87 share->s_next = file->f_shares;
88 file->f_shares = share;
89
90update:
91 share->s_access_deny_bmap |= LOCKD_FSH_BIT(access, mode);
92 nlm_recompute_share(share);
93 return nlm_granted;
94}
95
96/**
97 * nlmsvc_unshare_file - delete a share
98 * @host: Network client peer
99 * @file: File to be unshared
100 * @oh: Share owner handle
101 * @access: Access mode of the SHARE being released
102 * @mode: Deny mode of the SHARE being released
103 *
104 * Returns an NLM status code.
105 */
106__be32
107nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
108 struct xdr_netobj *oh, u32 access, u32 mode)
109{
110 struct lockd_share *share, **shpp;
111
112 if (nlmsvc_file_cannot_lock(file))
113 return nlm_lck_denied_nolocks;
114
115 for (shpp = &file->f_shares; (share = *shpp) != NULL;
116 shpp = &share->s_next) {
117 if (share->s_host == host && nlm_cmp_owner(share, oh)) {
118 share->s_access_deny_bmap &= ~LOCKD_FSH_BIT(access, mode);
119 nlm_recompute_share(share);
120 if (!share->s_access_deny_bmap) {
121 *shpp = share->s_next;
122 kfree(share);
123 }
124 return nlm_granted;
125 }
126 }
127
128 /* X/Open spec says return success even if there was no
129 * corresponding share. */
130 return nlm_granted;
131}
132
133/*
134 * Traverse all shares for a given file, and delete
135 * those owned by the given (type of) host
136 */
137void nlmsvc_traverse_shares(struct nlm_host *host, struct nlm_file *file,
138 nlm_host_match_fn_t match)
139{
140 struct lockd_share *share, **shpp;
141
142 shpp = &file->f_shares;
143 while ((share = *shpp) != NULL) {
144 if (match(share->s_host, host)) {
145 *shpp = share->s_next;
146 kfree(share);
147 continue;
148 }
149 shpp = &share->s_next;
150 }
151}