1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * This file contains all the stubs needed when communicating with lockd.
4 * This level of indirection is necessary so we can run nfsd+lockd without
5 * requiring the nfs client to be compiled in/loaded, and vice versa.
6 *
7 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
8 */
9
10 #include <linux/file.h>
11 #include <linux/lockd/bind.h>
12 #include "nfsd.h"
13 #include "vfs.h"
14
15 #define NFSDDBG_FACILITY NFSDDBG_LOCKD
16
17 /**
18 * nlm_fopen - Open an NFSD file
19 * @rqstp: NLM RPC procedure execution context
20 * @f: NFS file handle to be opened
21 * @filp: OUT: an opened struct file
22 * @flags: the POSIX open flags to use
23 *
24 * nlm_fopen() holds the dentry reference until nlm_fclose() releases it.
25 *
26 * Returns zero on success or a negative errno value if the file
27 * cannot be opened.
28 */
nlm_fopen(struct svc_rqst * rqstp,struct nfs_fh * f,struct file ** filp,int flags)29 static int nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f,
30 struct file **filp, int flags)
31 {
32 __be32 nfserr;
33 int access;
34 struct svc_fh fh;
35
36 /* must initialize before using! but maxsize doesn't matter */
37 fh_init(&fh,0);
38 fh.fh_handle.fh_size = f->size;
39 memcpy(&fh.fh_handle.fh_raw, f->data, f->size);
40 fh.fh_export = NULL;
41
42 /*
43 * Allow BYPASS_GSS as some client implementations use AUTH_SYS
44 * for NLM even when GSS is used for NFS.
45 * Allow OWNER_OVERRIDE as permission might have been changed
46 * after the file was opened.
47 * Pass MAY_NLM so that authentication can be completely bypassed
48 * if NFSEXP_NOAUTHNLM is set. Some older clients use AUTH_NULL
49 * for NLM requests.
50 */
51 access = (flags == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
52 access |= NFSD_MAY_NLM | NFSD_MAY_OWNER_OVERRIDE | NFSD_MAY_BYPASS_GSS;
53 nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
54 fh_put(&fh);
55
56 switch (nfserr) {
57 case nfs_ok:
58 break;
59 case nfserr_jukebox:
60 /*
61 * This error can indicate a presence of a conflicting
62 * delegation to an NLM lock request. Options are:
63 * (1) For now, drop this request and make the client
64 * retry. When delegation is returned, client's lock retry
65 * will complete.
66 * (2) NLM4_DENIED as per "spec" signals to the client
67 * that the lock is unavailable now but client can retry.
68 * Linux client implementation does not. It treats
69 * NLM4_DENIED same as NLM4_FAILED and fails the request.
70 * (3) For the future, treat this as blocked lock and try
71 * to callback when the delegation is returned but might
72 * not have a proper lock request to block on.
73 */
74 return -EWOULDBLOCK;
75 case nfserr_stale:
76 return -ESTALE;
77 default:
78 return -ENOLCK;
79 }
80
81 return 0;
82 }
83
84 /**
85 * nlm_fclose - Close an NFSD file
86 * @filp: a struct file that was opened by nlm_fopen()
87 */
88 static void
nlm_fclose(struct file * filp)89 nlm_fclose(struct file *filp)
90 {
91 fput(filp);
92 }
93
94 static const struct nlmsvc_binding nfsd_nlm_ops = {
95 .owner = THIS_MODULE,
96 .fopen = nlm_fopen, /* open file for locking */
97 .fclose = nlm_fclose, /* close file */
98 };
99
100 void
nfsd_lockd_init(void)101 nfsd_lockd_init(void)
102 {
103 dprintk("nfsd: initializing lockd\n");
104 rcu_assign_pointer(nlmsvc_ops, &nfsd_nlm_ops);
105 }
106
107 void
nfsd_lockd_shutdown(void)108 nfsd_lockd_shutdown(void)
109 {
110 RCU_INIT_POINTER(nlmsvc_ops, NULL);
111 synchronize_rcu();
112 }
113