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Linux/fs/lockd/mon.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * linux/fs/lockd/mon.c
  4  *
  5  * The kernel statd client.
  6  *
  7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  8  */
  9 
 10 #include <linux/types.h>
 11 #include <linux/kernel.h>
 12 #include <linux/ktime.h>
 13 #include <linux/slab.h>
 14 
 15 #include <linux/sunrpc/clnt.h>
 16 #include <linux/sunrpc/addr.h>
 17 #include <linux/sunrpc/xprtsock.h>
 18 #include <linux/sunrpc/svc.h>
 19 #include <linux/lockd/lockd.h>
 20 
 21 #include <asm/unaligned.h>
 22 
 23 #include "netns.h"
 24 
 25 #define NLMDBG_FACILITY         NLMDBG_MONITOR
 26 #define NSM_PROGRAM             100024
 27 #define NSM_VERSION             1
 28 
 29 enum {
 30         NSMPROC_NULL,
 31         NSMPROC_STAT,
 32         NSMPROC_MON,
 33         NSMPROC_UNMON,
 34         NSMPROC_UNMON_ALL,
 35         NSMPROC_SIMU_CRASH,
 36         NSMPROC_NOTIFY,
 37 };
 38 
 39 struct nsm_args {
 40         struct nsm_private      *priv;
 41         u32                     prog;           /* RPC callback info */
 42         u32                     vers;
 43         u32                     proc;
 44 
 45         char                    *mon_name;
 46         const char              *nodename;
 47 };
 48 
 49 struct nsm_res {
 50         u32                     status;
 51         u32                     state;
 52 };
 53 
 54 static const struct rpc_program nsm_program;
 55 static                          DEFINE_SPINLOCK(nsm_lock);
 56 
 57 /*
 58  * Local NSM state
 59  */
 60 u32     __read_mostly           nsm_local_state;
 61 bool    __read_mostly           nsm_use_hostnames;
 62 
 63 static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
 64 {
 65         return (struct sockaddr *)&nsm->sm_addr;
 66 }
 67 
 68 static struct rpc_clnt *nsm_create(struct net *net, const char *nodename)
 69 {
 70         struct sockaddr_in sin = {
 71                 .sin_family             = AF_INET,
 72                 .sin_addr.s_addr        = htonl(INADDR_LOOPBACK),
 73         };
 74         struct rpc_create_args args = {
 75                 .net                    = net,
 76                 .protocol               = XPRT_TRANSPORT_TCP,
 77                 .address                = (struct sockaddr *)&sin,
 78                 .addrsize               = sizeof(sin),
 79                 .servername             = "rpc.statd",
 80                 .nodename               = nodename,
 81                 .program                = &nsm_program,
 82                 .version                = NSM_VERSION,
 83                 .authflavor             = RPC_AUTH_NULL,
 84                 .flags                  = RPC_CLNT_CREATE_NOPING,
 85                 .cred                   = current_cred(),
 86         };
 87 
 88         return rpc_create(&args);
 89 }
 90 
 91 static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
 92                          const struct nlm_host *host)
 93 {
 94         int             status;
 95         struct rpc_clnt *clnt;
 96         struct nsm_args args = {
 97                 .priv           = &nsm->sm_priv,
 98                 .prog           = NLM_PROGRAM,
 99                 .vers           = 3,
100                 .proc           = NLMPROC_NSM_NOTIFY,
101                 .mon_name       = nsm->sm_mon_name,
102                 .nodename       = host->nodename,
103         };
104         struct rpc_message msg = {
105                 .rpc_argp       = &args,
106                 .rpc_resp       = res,
107         };
108 
109         memset(res, 0, sizeof(*res));
110 
111         clnt = nsm_create(host->net, host->nodename);
112         if (IS_ERR(clnt)) {
113                 dprintk("lockd: failed to create NSM upcall transport, "
114                         "status=%ld, net=%x\n", PTR_ERR(clnt),
115                         host->net->ns.inum);
116                 return PTR_ERR(clnt);
117         }
118 
119         msg.rpc_proc = &clnt->cl_procinfo[proc];
120         status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
121         if (status == -ECONNREFUSED) {
122                 dprintk("lockd: NSM upcall RPC failed, status=%d, forcing rebind\n",
123                                 status);
124                 rpc_force_rebind(clnt);
125                 status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
126         }
127         if (status < 0)
128                 dprintk("lockd: NSM upcall RPC failed, status=%d\n",
129                                 status);
130         else
131                 status = 0;
132 
133         rpc_shutdown_client(clnt);
134         return status;
135 }
136 
137 /**
138  * nsm_monitor - Notify a peer in case we reboot
139  * @host: pointer to nlm_host of peer to notify
140  *
141  * If this peer is not already monitored, this function sends an
142  * upcall to the local rpc.statd to record the name/address of
143  * the peer to notify in case we reboot.
144  *
145  * Returns zero if the peer is monitored by the local rpc.statd;
146  * otherwise a negative errno value is returned.
147  */
148 int nsm_monitor(const struct nlm_host *host)
149 {
150         struct nsm_handle *nsm = host->h_nsmhandle;
151         struct nsm_res  res;
152         int             status;
153 
154         dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
155 
156         if (nsm->sm_monitored)
157                 return 0;
158 
159         /*
160          * Choose whether to record the caller_name or IP address of
161          * this peer in the local rpc.statd's database.
162          */
163         nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
164 
165         status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host);
166         if (unlikely(res.status != 0))
167                 status = -EIO;
168         if (unlikely(status < 0)) {
169                 pr_notice_ratelimited("lockd: cannot monitor %s\n", nsm->sm_name);
170                 return status;
171         }
172 
173         nsm->sm_monitored = 1;
174         if (unlikely(nsm_local_state != res.state)) {
175                 nsm_local_state = res.state;
176                 dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
177         }
178         return 0;
179 }
180 
181 /**
182  * nsm_unmonitor - Unregister peer notification
183  * @host: pointer to nlm_host of peer to stop monitoring
184  *
185  * If this peer is monitored, this function sends an upcall to
186  * tell the local rpc.statd not to send this peer a notification
187  * when we reboot.
188  */
189 void nsm_unmonitor(const struct nlm_host *host)
190 {
191         struct nsm_handle *nsm = host->h_nsmhandle;
192         struct nsm_res  res;
193         int status;
194 
195         if (refcount_read(&nsm->sm_count) == 1
196          && nsm->sm_monitored && !nsm->sm_sticky) {
197                 dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
198 
199                 status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host);
200                 if (res.status != 0)
201                         status = -EIO;
202                 if (status < 0)
203                         printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
204                                         nsm->sm_name);
205                 else
206                         nsm->sm_monitored = 0;
207         }
208 }
209 
210 static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
211                                         const char *hostname, const size_t len)
212 {
213         struct nsm_handle *nsm;
214 
215         list_for_each_entry(nsm, nsm_handles, sm_link)
216                 if (strlen(nsm->sm_name) == len &&
217                     memcmp(nsm->sm_name, hostname, len) == 0)
218                         return nsm;
219         return NULL;
220 }
221 
222 static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
223                                         const struct sockaddr *sap)
224 {
225         struct nsm_handle *nsm;
226 
227         list_for_each_entry(nsm, nsm_handles, sm_link)
228                 if (rpc_cmp_addr(nsm_addr(nsm), sap))
229                         return nsm;
230         return NULL;
231 }
232 
233 static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
234                                         const struct nsm_private *priv)
235 {
236         struct nsm_handle *nsm;
237 
238         list_for_each_entry(nsm, nsm_handles, sm_link)
239                 if (memcmp(nsm->sm_priv.data, priv->data,
240                                         sizeof(priv->data)) == 0)
241                         return nsm;
242         return NULL;
243 }
244 
245 /*
246  * Construct a unique cookie to match this nsm_handle to this monitored
247  * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
248  * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
249  * requests.
250  *
251  * The NSM protocol requires that these cookies be unique while the
252  * system is running.  We prefer a stronger requirement of making them
253  * unique across reboots.  If user space bugs cause a stale cookie to
254  * be sent to the kernel, it could cause the wrong host to lose its
255  * lock state if cookies were not unique across reboots.
256  *
257  * The cookies are exposed only to local user space via loopback.  They
258  * do not appear on the physical network.  If we want greater security
259  * for some reason, nsm_init_private() could perform a one-way hash to
260  * obscure the contents of the cookie.
261  */
262 static void nsm_init_private(struct nsm_handle *nsm)
263 {
264         u64 *p = (u64 *)&nsm->sm_priv.data;
265         s64 ns;
266 
267         ns = ktime_get_ns();
268         put_unaligned(ns, p);
269         put_unaligned((unsigned long)nsm, p + 1);
270 }
271 
272 static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
273                                             const size_t salen,
274                                             const char *hostname,
275                                             const size_t hostname_len)
276 {
277         struct nsm_handle *new;
278 
279         new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
280         if (unlikely(new == NULL))
281                 return NULL;
282 
283         refcount_set(&new->sm_count, 1);
284         new->sm_name = (char *)(new + 1);
285         memcpy(nsm_addr(new), sap, salen);
286         new->sm_addrlen = salen;
287         nsm_init_private(new);
288 
289         if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
290                                         sizeof(new->sm_addrbuf)) == 0)
291                 (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
292                                 "unsupported address family");
293         memcpy(new->sm_name, hostname, hostname_len);
294         new->sm_name[hostname_len] = '\0';
295 
296         return new;
297 }
298 
299 /**
300  * nsm_get_handle - Find or create a cached nsm_handle
301  * @net: network namespace
302  * @sap: pointer to socket address of handle to find
303  * @salen: length of socket address
304  * @hostname: pointer to C string containing hostname to find
305  * @hostname_len: length of C string
306  *
307  * Behavior is modulated by the global nsm_use_hostnames variable.
308  *
309  * Returns a cached nsm_handle after bumping its ref count, or
310  * returns a fresh nsm_handle if a handle that matches @sap and/or
311  * @hostname cannot be found in the handle cache.  Returns NULL if
312  * an error occurs.
313  */
314 struct nsm_handle *nsm_get_handle(const struct net *net,
315                                   const struct sockaddr *sap,
316                                   const size_t salen, const char *hostname,
317                                   const size_t hostname_len)
318 {
319         struct nsm_handle *cached, *new = NULL;
320         struct lockd_net *ln = net_generic(net, lockd_net_id);
321 
322         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
323                 if (printk_ratelimit()) {
324                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
325                                             "in NFS lock request\n",
326                                 (int)hostname_len, hostname);
327                 }
328                 return NULL;
329         }
330 
331 retry:
332         spin_lock(&nsm_lock);
333 
334         if (nsm_use_hostnames && hostname != NULL)
335                 cached = nsm_lookup_hostname(&ln->nsm_handles,
336                                         hostname, hostname_len);
337         else
338                 cached = nsm_lookup_addr(&ln->nsm_handles, sap);
339 
340         if (cached != NULL) {
341                 refcount_inc(&cached->sm_count);
342                 spin_unlock(&nsm_lock);
343                 kfree(new);
344                 dprintk("lockd: found nsm_handle for %s (%s), "
345                                 "cnt %d\n", cached->sm_name,
346                                 cached->sm_addrbuf,
347                                 refcount_read(&cached->sm_count));
348                 return cached;
349         }
350 
351         if (new != NULL) {
352                 list_add(&new->sm_link, &ln->nsm_handles);
353                 spin_unlock(&nsm_lock);
354                 dprintk("lockd: created nsm_handle for %s (%s)\n",
355                                 new->sm_name, new->sm_addrbuf);
356                 return new;
357         }
358 
359         spin_unlock(&nsm_lock);
360 
361         new = nsm_create_handle(sap, salen, hostname, hostname_len);
362         if (unlikely(new == NULL))
363                 return NULL;
364         goto retry;
365 }
366 
367 /**
368  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
369  * @net:  network namespace
370  * @info: pointer to NLMPROC_SM_NOTIFY arguments
371  *
372  * Returns a matching nsm_handle if found in the nsm cache. The returned
373  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
374  * error occurred.
375  */
376 struct nsm_handle *nsm_reboot_lookup(const struct net *net,
377                                 const struct nlm_reboot *info)
378 {
379         struct nsm_handle *cached;
380         struct lockd_net *ln = net_generic(net, lockd_net_id);
381 
382         spin_lock(&nsm_lock);
383 
384         cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
385         if (unlikely(cached == NULL)) {
386                 spin_unlock(&nsm_lock);
387                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
388                                 info->len, info->mon);
389                 return cached;
390         }
391 
392         refcount_inc(&cached->sm_count);
393         spin_unlock(&nsm_lock);
394 
395         dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
396                         cached->sm_name, cached->sm_addrbuf,
397                         refcount_read(&cached->sm_count));
398         return cached;
399 }
400 
401 /**
402  * nsm_release - Release an NSM handle
403  * @nsm: pointer to handle to be released
404  *
405  */
406 void nsm_release(struct nsm_handle *nsm)
407 {
408         if (refcount_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
409                 list_del(&nsm->sm_link);
410                 spin_unlock(&nsm_lock);
411                 dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
412                                 nsm->sm_name, nsm->sm_addrbuf);
413                 kfree(nsm);
414         }
415 }
416 
417 /*
418  * XDR functions for NSM.
419  *
420  * See http://www.opengroup.org/ for details on the Network
421  * Status Monitor wire protocol.
422  */
423 
424 static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
425 {
426         const u32 len = strlen(string);
427         __be32 *p;
428 
429         p = xdr_reserve_space(xdr, 4 + len);
430         xdr_encode_opaque(p, string, len);
431 }
432 
433 /*
434  * "mon_name" specifies the host to be monitored.
435  */
436 static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
437 {
438         encode_nsm_string(xdr, argp->mon_name);
439 }
440 
441 /*
442  * The "my_id" argument specifies the hostname and RPC procedure
443  * to be called when the status manager receives notification
444  * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
445  * has changed.
446  */
447 static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
448 {
449         __be32 *p;
450 
451         encode_nsm_string(xdr, argp->nodename);
452         p = xdr_reserve_space(xdr, 4 + 4 + 4);
453         *p++ = cpu_to_be32(argp->prog);
454         *p++ = cpu_to_be32(argp->vers);
455         *p = cpu_to_be32(argp->proc);
456 }
457 
458 /*
459  * The "mon_id" argument specifies the non-private arguments
460  * of an NSMPROC_MON or NSMPROC_UNMON call.
461  */
462 static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
463 {
464         encode_mon_name(xdr, argp);
465         encode_my_id(xdr, argp);
466 }
467 
468 /*
469  * The "priv" argument may contain private information required
470  * by the NSMPROC_MON call. This information will be supplied in the
471  * NLMPROC_SM_NOTIFY call.
472  */
473 static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
474 {
475         __be32 *p;
476 
477         p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
478         xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
479 }
480 
481 static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
482                             const void *argp)
483 {
484         encode_mon_id(xdr, argp);
485         encode_priv(xdr, argp);
486 }
487 
488 static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
489                               const void *argp)
490 {
491         encode_mon_id(xdr, argp);
492 }
493 
494 static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
495                                 struct xdr_stream *xdr,
496                                 void *data)
497 {
498         struct nsm_res *resp = data;
499         __be32 *p;
500 
501         p = xdr_inline_decode(xdr, 4 + 4);
502         if (unlikely(p == NULL))
503                 return -EIO;
504         resp->status = be32_to_cpup(p++);
505         resp->state = be32_to_cpup(p);
506 
507         dprintk("lockd: %s status %d state %d\n",
508                 __func__, resp->status, resp->state);
509         return 0;
510 }
511 
512 static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
513                             struct xdr_stream *xdr,
514                             void *data)
515 {
516         struct nsm_res *resp = data;
517         __be32 *p;
518 
519         p = xdr_inline_decode(xdr, 4);
520         if (unlikely(p == NULL))
521                 return -EIO;
522         resp->state = be32_to_cpup(p);
523 
524         dprintk("lockd: %s state %d\n", __func__, resp->state);
525         return 0;
526 }
527 
528 #define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
529 #define SM_my_id_sz     (SM_my_name_sz+3)
530 #define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
531 #define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
532 #define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
533 #define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
534 #define SM_monres_sz    2
535 #define SM_unmonres_sz  1
536 
537 static const struct rpc_procinfo nsm_procedures[] = {
538 [NSMPROC_MON] = {
539                 .p_proc         = NSMPROC_MON,
540                 .p_encode       = nsm_xdr_enc_mon,
541                 .p_decode       = nsm_xdr_dec_stat_res,
542                 .p_arglen       = SM_mon_sz,
543                 .p_replen       = SM_monres_sz,
544                 .p_statidx      = NSMPROC_MON,
545                 .p_name         = "MONITOR",
546         },
547 [NSMPROC_UNMON] = {
548                 .p_proc         = NSMPROC_UNMON,
549                 .p_encode       = nsm_xdr_enc_unmon,
550                 .p_decode       = nsm_xdr_dec_stat,
551                 .p_arglen       = SM_mon_id_sz,
552                 .p_replen       = SM_unmonres_sz,
553                 .p_statidx      = NSMPROC_UNMON,
554                 .p_name         = "UNMONITOR",
555         },
556 };
557 
558 static unsigned int nsm_version1_counts[ARRAY_SIZE(nsm_procedures)];
559 static const struct rpc_version nsm_version1 = {
560         .number         = 1,
561         .nrprocs        = ARRAY_SIZE(nsm_procedures),
562         .procs          = nsm_procedures,
563         .counts         = nsm_version1_counts,
564 };
565 
566 static const struct rpc_version *nsm_version[] = {
567         [1] = &nsm_version1,
568 };
569 
570 static struct rpc_stat          nsm_stats;
571 
572 static const struct rpc_program nsm_program = {
573         .name           = "statd",
574         .number         = NSM_PROGRAM,
575         .nrvers         = ARRAY_SIZE(nsm_version),
576         .version        = nsm_version,
577         .stats          = &nsm_stats
578 };
579 

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