1 /* $NetBSD: nfs_lock.c,v 1.3 2020/01/02 15:42:26 thorpej Exp $ */
2 /*-
3 * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Berkeley Software Design Inc's name may not be used to endorse or
14 * promote products derived from this software without specific prior
15 * written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * from BSDI nfs_lock.c,v 2.4 1998/12/14 23:49:56 jch Exp
30 */
31
32 #include <sys/cdefs.h>
33 /* __FBSDID("FreeBSD: head/sys/nfs/nfs_lock.c 303382 2016-07-27 11:08:59Z kib "); */
34 __RCSID("$NetBSD: nfs_lock.c,v 1.3 2020/01/02 15:42:26 thorpej Exp $");
35
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/conf.h>
39 #include <sys/fcntl.h>
40 #include <sys/kernel.h> /* for hz */
41 #include <sys/limits.h>
42 #include <sys/lock.h>
43 #include <sys/malloc.h>
44 #include <sys/lockf.h> /* for hz */ /* Must come after sys/malloc.h */
45 #include <sys/mbuf.h>
46 #include <sys/mount.h>
47 #include <sys/namei.h>
48 #include <sys/priv.h>
49 #include <sys/proc.h>
50 #include <sys/resourcevar.h>
51 #include <sys/socket.h>
52 #include <sys/socket.h>
53 #include <sys/unistd.h>
54 #include <sys/vnode.h>
55
56 #include <net/if.h>
57
58 #include <fs/nfs/common/nfsproto.h>
59 #include <fs/nfs/common/nfs_lock.h>
60 #include <fs/nfs/client/nfs.h>
61 #include <fs/nfs/client/nfsmount.h>
62 #include <fs/nfs/client/nfsnode.h>
63 #include <fs/nfs/client/nlminfo.h>
64
65 extern void (*nlminfo_release_p)(struct proc *p);
66
67 vop_advlock_t *nfs_advlock_p = nfs_dolock;
68 vop_reclaim_t *nfs_reclaim_p = NULL;
69
70 static MALLOC_DEFINE(M_NFSLOCK, "nfsclient_lock", "NFS lock request");
71 static MALLOC_DEFINE(M_NLMINFO, "nfsclient_nlminfo",
72 "NFS lock process structure");
73
74 static int nfslockdans(struct thread *td, struct lockd_ans *ansp);
75 static void nlminfo_release(struct proc *p);
76 /*
77 * --------------------------------------------------------------------
78 * A miniature device driver which the userland uses to talk to us.
79 *
80 */
81
82 static struct cdev *nfslock_dev;
83 static struct mtx nfslock_mtx;
84 static int nfslock_isopen;
85 static TAILQ_HEAD(,__lock_msg) nfslock_list;
86
87 static int
nfslock_open(struct cdev * dev,int oflags,int devtype,struct thread * td)88 nfslock_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
89 {
90 int error;
91
92 error = priv_check(td, PRIV_NFS_LOCKD);
93 if (error)
94 return (error);
95
96 mtx_lock(&nfslock_mtx);
97 if (!nfslock_isopen) {
98 error = 0;
99 nfslock_isopen = 1;
100 } else {
101 error = EOPNOTSUPP;
102 }
103 mtx_unlock(&nfslock_mtx);
104
105 return (error);
106 }
107
108 static int
nfslock_close(struct cdev * dev,int fflag,int devtype,struct thread * td)109 nfslock_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
110 {
111 struct __lock_msg *lm;
112
113 mtx_lock(&nfslock_mtx);
114 nfslock_isopen = 0;
115 while (!TAILQ_EMPTY(&nfslock_list)) {
116 lm = TAILQ_FIRST(&nfslock_list);
117 /* XXX: answer request */
118 TAILQ_REMOVE(&nfslock_list, lm, lm_link);
119 free(lm, M_NFSLOCK);
120 }
121 mtx_unlock(&nfslock_mtx);
122 return (0);
123 }
124
125 static int
nfslock_read(struct cdev * dev,struct uio * uio,int ioflag)126 nfslock_read(struct cdev *dev, struct uio *uio, int ioflag)
127 {
128 int error;
129 struct __lock_msg *lm;
130
131 if (uio->uio_resid != sizeof *lm)
132 return (EOPNOTSUPP);
133 lm = NULL;
134 error = 0;
135 mtx_lock(&nfslock_mtx);
136 while (TAILQ_EMPTY(&nfslock_list)) {
137 error = msleep(&nfslock_list, &nfslock_mtx, PSOCK | PCATCH,
138 "nfslockd", 0);
139 if (error)
140 break;
141 }
142 if (!error) {
143 lm = TAILQ_FIRST(&nfslock_list);
144 TAILQ_REMOVE(&nfslock_list, lm, lm_link);
145 }
146 mtx_unlock(&nfslock_mtx);
147 if (!error) {
148 error = uiomove(lm, sizeof *lm, uio);
149 free(lm, M_NFSLOCK);
150 }
151 return (error);
152 }
153
154 static int
nfslock_write(struct cdev * dev,struct uio * uio,int ioflag)155 nfslock_write(struct cdev *dev, struct uio *uio, int ioflag)
156 {
157 struct lockd_ans la;
158 int error;
159
160 if (uio->uio_resid != sizeof la)
161 return (EOPNOTSUPP);
162 error = uiomove(&la, sizeof la, uio);
163 if (!error)
164 error = nfslockdans(curthread, &la);
165 return (error);
166 }
167
168 static int
nfslock_send(struct __lock_msg * lm)169 nfslock_send(struct __lock_msg *lm)
170 {
171 struct __lock_msg *lm2;
172 int error;
173
174 error = 0;
175 lm2 = malloc(sizeof *lm2, M_NFSLOCK, M_WAITOK);
176 mtx_lock(&nfslock_mtx);
177 if (nfslock_isopen) {
178 memcpy(lm2, lm, sizeof *lm2);
179 TAILQ_INSERT_TAIL(&nfslock_list, lm2, lm_link);
180 wakeup(&nfslock_list);
181 } else {
182 error = EOPNOTSUPP;
183 }
184 mtx_unlock(&nfslock_mtx);
185 if (error)
186 free(lm2, M_NFSLOCK);
187 return (error);
188 }
189
190 static struct cdevsw nfslock_cdevsw = {
191 .d_version = D_VERSION,
192 .d_open = nfslock_open,
193 .d_close = nfslock_close,
194 .d_read = nfslock_read,
195 .d_write = nfslock_write,
196 .d_name = "nfslock"
197 };
198
199 static int
nfslock_modevent(module_t mod __unused,int type,void * data __unused)200 nfslock_modevent(module_t mod __unused, int type, void *data __unused)
201 {
202
203 switch (type) {
204 case MOD_LOAD:
205 if (bootverbose)
206 printf("nfslock: pseudo-device\n");
207 mtx_init(&nfslock_mtx, "nfslock", NULL, MTX_DEF);
208 TAILQ_INIT(&nfslock_list);
209 nlminfo_release_p = nlminfo_release;
210 nfslock_dev = make_dev(&nfslock_cdevsw, 0,
211 UID_ROOT, GID_KMEM, 0600, _PATH_NFSLCKDEV);
212 return (0);
213 default:
214 return (EOPNOTSUPP);
215 }
216 }
217
218 DEV_MODULE(nfslock, nfslock_modevent, NULL);
219 MODULE_VERSION(nfslock, 1);
220
221
222 /*
223 * XXX
224 * We have to let the process know if the call succeeded. I'm using an extra
225 * field in the p_nlminfo field in the proc structure, as it is already for
226 * lockd stuff.
227 */
228
229 /*
230 * nfs_advlock --
231 * NFS advisory byte-level locks.
232 *
233 * The vnode shall be (shared) locked on the entry, it is
234 * unconditionally unlocked after.
235 */
236 int
nfs_dolock(struct vop_advlock_args * ap)237 nfs_dolock(struct vop_advlock_args *ap)
238 {
239 LOCKD_MSG msg;
240 struct thread *td;
241 struct vnode *vp;
242 int error;
243 struct flock *fl;
244 struct proc *p;
245 struct nfsmount *nmp;
246 struct timeval btv;
247
248 td = curthread;
249 p = td->td_proc;
250
251 vp = ap->a_vp;
252 fl = ap->a_fl;
253 nmp = VFSTONFS(vp->v_mount);
254
255 ASSERT_VOP_LOCKED(vp, "nfs_dolock");
256
257 nmp->nm_getinfo(vp, msg.lm_fh, &msg.lm_fh_len, &msg.lm_addr,
258 &msg.lm_nfsv3, NULL, NULL);
259 VOP_UNLOCK(vp, 0);
260
261 /*
262 * the NLM protocol doesn't allow the server to return an error
263 * on ranges, so we do it.
264 */
265 if (fl->l_whence != SEEK_END) {
266 if ((fl->l_whence != SEEK_CUR && fl->l_whence != SEEK_SET) ||
267 fl->l_start < 0 ||
268 (fl->l_len < 0 &&
269 (fl->l_start == 0 || fl->l_start + fl->l_len < 0)))
270 return (EINVAL);
271 if (fl->l_len > 0 &&
272 (fl->l_len - 1 > OFF_MAX - fl->l_start))
273 return (EOVERFLOW);
274 }
275
276 /*
277 * Fill in the information structure.
278 */
279 msg.lm_version = LOCKD_MSG_VERSION;
280 msg.lm_msg_ident.pid = p->p_pid;
281
282 mtx_lock(&Giant);
283 /*
284 * if there is no nfsowner table yet, allocate one.
285 */
286 if (p->p_nlminfo == NULL) {
287 p->p_nlminfo = malloc(sizeof(struct nlminfo),
288 M_NLMINFO, M_WAITOK | M_ZERO);
289 p->p_nlminfo->pid_start = p->p_stats->p_start;
290 getmicroboottime(&btv);
291 timevaladd(&p->p_nlminfo->pid_start, &btv);
292 }
293 msg.lm_msg_ident.pid_start = p->p_nlminfo->pid_start;
294 msg.lm_msg_ident.msg_seq = ++(p->p_nlminfo->msg_seq);
295
296 msg.lm_fl = *fl;
297 msg.lm_wait = ap->a_flags & F_WAIT;
298 msg.lm_getlk = ap->a_op == F_GETLK;
299 cru2x(td->td_ucred, &msg.lm_cred);
300
301 for (;;) {
302 error = nfslock_send(&msg);
303 if (error)
304 goto out;
305
306 /* Unlocks succeed immediately. */
307 if (fl->l_type == F_UNLCK)
308 goto out;
309
310 /*
311 * Retry after 20 seconds if we haven't gotten a response yet.
312 * This number was picked out of thin air... but is longer
313 * then even a reasonably loaded system should take (at least
314 * on a local network). XXX Probably should use a back-off
315 * scheme.
316 *
317 * XXX: No PCATCH here since we currently have no useful
318 * way to signal to the userland rpc.lockd that the request
319 * has been aborted. Once the rpc.lockd implementation
320 * can handle aborts, and we report them properly,
321 * PCATCH can be put back. In the mean time, if we did
322 * permit aborting, the lock attempt would "get lost"
323 * and the lock would get stuck in the locked state.
324 */
325 error = tsleep(p->p_nlminfo, PUSER, "lockd", 20*hz);
326 if (error != 0) {
327 if (error == EWOULDBLOCK) {
328 /*
329 * We timed out, so we rewrite the request
330 * to the fifo.
331 */
332 continue;
333 }
334
335 break;
336 }
337
338 if (msg.lm_getlk && p->p_nlminfo->retcode == 0) {
339 if (p->p_nlminfo->set_getlk_pid) {
340 fl->l_sysid = 0; /* XXX */
341 fl->l_pid = p->p_nlminfo->getlk_pid;
342 } else {
343 fl->l_type = F_UNLCK;
344 }
345 }
346 error = p->p_nlminfo->retcode;
347 break;
348 }
349 out:
350 mtx_unlock(&Giant);
351 return (error);
352 }
353
354 /*
355 * nfslockdans --
356 * NFS advisory byte-level locks answer from the lock daemon.
357 */
358 static int
nfslockdans(struct thread * td,struct lockd_ans * ansp)359 nfslockdans(struct thread *td, struct lockd_ans *ansp)
360 {
361 struct proc *targetp;
362
363 /* the version should match, or we're out of sync */
364 if (ansp->la_vers != LOCKD_ANS_VERSION)
365 return (EINVAL);
366
367 /* Find the process, set its return errno and wake it up. */
368 if ((targetp = pfind(ansp->la_msg_ident.pid)) == NULL)
369 return (ESRCH);
370
371 /* verify the pid hasn't been reused (if we can), and it isn't waiting
372 * for an answer from a more recent request. We return an EPIPE if
373 * the match fails, because we've already used ESRCH above, and this
374 * is sort of like writing on a pipe after the reader has closed it.
375 */
376 if (targetp->p_nlminfo == NULL ||
377 ((ansp->la_msg_ident.msg_seq != -1) &&
378 (timevalcmp(&targetp->p_nlminfo->pid_start,
379 &ansp->la_msg_ident.pid_start, !=) ||
380 targetp->p_nlminfo->msg_seq != ansp->la_msg_ident.msg_seq))) {
381 PROC_UNLOCK(targetp);
382 return (EPIPE);
383 }
384
385 targetp->p_nlminfo->retcode = ansp->la_errno;
386 targetp->p_nlminfo->set_getlk_pid = ansp->la_set_getlk_pid;
387 targetp->p_nlminfo->getlk_pid = ansp->la_getlk_pid;
388
389 wakeup(targetp->p_nlminfo);
390
391 PROC_UNLOCK(targetp);
392 return (0);
393 }
394
395 /*
396 * Free nlminfo attached to process.
397 */
398 void
nlminfo_release(struct proc * p)399 nlminfo_release(struct proc *p)
400 {
401 free(p->p_nlminfo, M_NLMINFO);
402 p->p_nlminfo = NULL;
403 }
404