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Linux/fs/nfs/callback.c

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  1 /*
  2  * linux/fs/nfs/callback.c
  3  *
  4  * Copyright (C) 2004 Trond Myklebust
  5  *
  6  * NFSv4 callback handling
  7  */
  8 
  9 #include <linux/completion.h>
 10 #include <linux/ip.h>
 11 #include <linux/module.h>
 12 #include <linux/sunrpc/svc.h>
 13 #include <linux/sunrpc/svcsock.h>
 14 #include <linux/nfs_fs.h>
 15 #include <linux/errno.h>
 16 #include <linux/mutex.h>
 17 #include <linux/freezer.h>
 18 #include <linux/kthread.h>
 19 #include <linux/sunrpc/svcauth_gss.h>
 20 #include <linux/sunrpc/bc_xprt.h>
 21 
 22 #include <net/inet_sock.h>
 23 
 24 #include "nfs4_fs.h"
 25 #include "callback.h"
 26 #include "internal.h"
 27 #include "netns.h"
 28 
 29 #define NFSDBG_FACILITY NFSDBG_CALLBACK
 30 
 31 struct nfs_callback_data {
 32         unsigned int users;
 33         struct svc_serv *serv;
 34         struct svc_rqst *rqst;
 35         struct task_struct *task;
 36 };
 37 
 38 static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
 39 static DEFINE_MUTEX(nfs_callback_mutex);
 40 static struct svc_program nfs4_callback_program;
 41 
 42 static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
 43 {
 44         int ret;
 45         struct nfs_net *nn = net_generic(net, nfs_net_id);
 46 
 47         ret = svc_create_xprt(serv, "tcp", net, PF_INET,
 48                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 49         if (ret <= 0)
 50                 goto out_err;
 51         nn->nfs_callback_tcpport = ret;
 52         dprintk("NFS: Callback listener port = %u (af %u, net %p)\n",
 53                         nn->nfs_callback_tcpport, PF_INET, net);
 54 
 55         ret = svc_create_xprt(serv, "tcp", net, PF_INET6,
 56                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 57         if (ret > 0) {
 58                 nn->nfs_callback_tcpport6 = ret;
 59                 dprintk("NFS: Callback listener port = %u (af %u, net %p)\n",
 60                                 nn->nfs_callback_tcpport6, PF_INET6, net);
 61         } else if (ret != -EAFNOSUPPORT)
 62                 goto out_err;
 63         return 0;
 64 
 65 out_err:
 66         return (ret) ? ret : -ENOMEM;
 67 }
 68 
 69 /*
 70  * This is the NFSv4 callback kernel thread.
 71  */
 72 static int
 73 nfs4_callback_svc(void *vrqstp)
 74 {
 75         int err;
 76         struct svc_rqst *rqstp = vrqstp;
 77 
 78         set_freezable();
 79 
 80         while (!kthread_should_stop()) {
 81                 /*
 82                  * Listen for a request on the socket
 83                  */
 84                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
 85                 if (err == -EAGAIN || err == -EINTR)
 86                         continue;
 87                 svc_process(rqstp);
 88         }
 89         return 0;
 90 }
 91 
 92 /*
 93  * Prepare to bring up the NFSv4 callback service
 94  */
 95 static struct svc_rqst *
 96 nfs4_callback_up(struct svc_serv *serv)
 97 {
 98         return svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);
 99 }
100 
101 #if defined(CONFIG_NFS_V4_1)
102 /*
103  * The callback service for NFSv4.1 callbacks
104  */
105 static int
106 nfs41_callback_svc(void *vrqstp)
107 {
108         struct svc_rqst *rqstp = vrqstp;
109         struct svc_serv *serv = rqstp->rq_server;
110         struct rpc_rqst *req;
111         int error;
112         DEFINE_WAIT(wq);
113 
114         set_freezable();
115 
116         while (!kthread_should_stop()) {
117                 if (try_to_freeze())
118                         continue;
119 
120                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
121                 spin_lock_bh(&serv->sv_cb_lock);
122                 if (!list_empty(&serv->sv_cb_list)) {
123                         req = list_first_entry(&serv->sv_cb_list,
124                                         struct rpc_rqst, rq_bc_list);
125                         list_del(&req->rq_bc_list);
126                         spin_unlock_bh(&serv->sv_cb_lock);
127                         finish_wait(&serv->sv_cb_waitq, &wq);
128                         dprintk("Invoking bc_svc_process()\n");
129                         error = bc_svc_process(serv, req, rqstp);
130                         dprintk("bc_svc_process() returned w/ error code= %d\n",
131                                 error);
132                 } else {
133                         spin_unlock_bh(&serv->sv_cb_lock);
134                         schedule();
135                         finish_wait(&serv->sv_cb_waitq, &wq);
136                 }
137                 flush_signals(current);
138         }
139         return 0;
140 }
141 
142 /*
143  * Bring up the NFSv4.1 callback service
144  */
145 static struct svc_rqst *
146 nfs41_callback_up(struct svc_serv *serv)
147 {
148         struct svc_rqst *rqstp;
149 
150         INIT_LIST_HEAD(&serv->sv_cb_list);
151         spin_lock_init(&serv->sv_cb_lock);
152         init_waitqueue_head(&serv->sv_cb_waitq);
153         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);
154         dprintk("--> %s return %d\n", __func__, PTR_ERR_OR_ZERO(rqstp));
155         return rqstp;
156 }
157 
158 static void nfs_minorversion_callback_svc_setup(struct svc_serv *serv,
159                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
160 {
161         *rqstpp = nfs41_callback_up(serv);
162         *callback_svc = nfs41_callback_svc;
163 }
164 
165 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
166                 struct svc_serv *serv)
167 {
168         if (minorversion)
169                 /*
170                  * Save the svc_serv in the transport so that it can
171                  * be referenced when the session backchannel is initialized
172                  */
173                 xprt->bc_serv = serv;
174 }
175 #else
176 static void nfs_minorversion_callback_svc_setup(struct svc_serv *serv,
177                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
178 {
179         *rqstpp = ERR_PTR(-ENOTSUPP);
180         *callback_svc = ERR_PTR(-ENOTSUPP);
181 }
182 
183 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
184                 struct svc_serv *serv)
185 {
186 }
187 #endif /* CONFIG_NFS_V4_1 */
188 
189 static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
190                                   struct svc_serv *serv)
191 {
192         struct svc_rqst *rqstp;
193         int (*callback_svc)(void *vrqstp);
194         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
195         int ret;
196 
197         nfs_callback_bc_serv(minorversion, xprt, serv);
198 
199         if (cb_info->task)
200                 return 0;
201 
202         switch (minorversion) {
203         case 0:
204                 /* v4.0 callback setup */
205                 rqstp = nfs4_callback_up(serv);
206                 callback_svc = nfs4_callback_svc;
207                 break;
208         default:
209                 nfs_minorversion_callback_svc_setup(serv,
210                                 &rqstp, &callback_svc);
211         }
212 
213         if (IS_ERR(rqstp))
214                 return PTR_ERR(rqstp);
215 
216         svc_sock_update_bufs(serv);
217 
218         cb_info->serv = serv;
219         cb_info->rqst = rqstp;
220         cb_info->task = kthread_create(callback_svc, cb_info->rqst,
221                                     "nfsv4.%u-svc", minorversion);
222         if (IS_ERR(cb_info->task)) {
223                 ret = PTR_ERR(cb_info->task);
224                 svc_exit_thread(cb_info->rqst);
225                 cb_info->rqst = NULL;
226                 cb_info->task = NULL;
227                 return ret;
228         }
229         rqstp->rq_task = cb_info->task;
230         wake_up_process(cb_info->task);
231         dprintk("nfs_callback_up: service started\n");
232         return 0;
233 }
234 
235 static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
236 {
237         struct nfs_net *nn = net_generic(net, nfs_net_id);
238 
239         if (--nn->cb_users[minorversion])
240                 return;
241 
242         dprintk("NFS: destroy per-net callback data; net=%p\n", net);
243         svc_shutdown_net(serv, net);
244 }
245 
246 static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
247                                struct net *net, struct rpc_xprt *xprt)
248 {
249         struct nfs_net *nn = net_generic(net, nfs_net_id);
250         int ret;
251 
252         if (nn->cb_users[minorversion]++)
253                 return 0;
254 
255         dprintk("NFS: create per-net callback data; net=%p\n", net);
256 
257         ret = svc_bind(serv, net);
258         if (ret < 0) {
259                 printk(KERN_WARNING "NFS: bind callback service failed\n");
260                 goto err_bind;
261         }
262 
263         ret = -EPROTONOSUPPORT;
264         if (minorversion == 0)
265                 ret = nfs4_callback_up_net(serv, net);
266         else if (xprt->ops->bc_up)
267                 ret = xprt->ops->bc_up(serv, net);
268 
269         if (ret < 0) {
270                 printk(KERN_ERR "NFS: callback service start failed\n");
271                 goto err_socks;
272         }
273         return 0;
274 
275 err_socks:
276         svc_rpcb_cleanup(serv, net);
277 err_bind:
278         dprintk("NFS: Couldn't create callback socket: err = %d; "
279                         "net = %p\n", ret, net);
280         return ret;
281 }
282 
283 static struct svc_serv_ops nfs_cb_sv_ops = {
284         .svo_enqueue_xprt       = svc_xprt_do_enqueue,
285 };
286 
287 static struct svc_serv *nfs_callback_create_svc(int minorversion)
288 {
289         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
290         struct svc_serv *serv;
291 
292         /*
293          * Check whether we're already up and running.
294          */
295         if (cb_info->task) {
296                 /*
297                  * Note: increase service usage, because later in case of error
298                  * svc_destroy() will be called.
299                  */
300                 svc_get(cb_info->serv);
301                 return cb_info->serv;
302         }
303 
304         /*
305          * Sanity check: if there's no task,
306          * we should be the first user ...
307          */
308         if (cb_info->users)
309                 printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
310                         cb_info->users);
311 
312         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, &nfs_cb_sv_ops);
313         if (!serv) {
314                 printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
315                 return ERR_PTR(-ENOMEM);
316         }
317         /* As there is only one thread we need to over-ride the
318          * default maximum of 80 connections
319          */
320         serv->sv_maxconn = 1024;
321         dprintk("nfs_callback_create_svc: service created\n");
322         return serv;
323 }
324 
325 /*
326  * Bring up the callback thread if it is not already up.
327  */
328 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
329 {
330         struct svc_serv *serv;
331         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
332         int ret;
333         struct net *net = xprt->xprt_net;
334 
335         mutex_lock(&nfs_callback_mutex);
336 
337         serv = nfs_callback_create_svc(minorversion);
338         if (IS_ERR(serv)) {
339                 ret = PTR_ERR(serv);
340                 goto err_create;
341         }
342 
343         ret = nfs_callback_up_net(minorversion, serv, net, xprt);
344         if (ret < 0)
345                 goto err_net;
346 
347         ret = nfs_callback_start_svc(minorversion, xprt, serv);
348         if (ret < 0)
349                 goto err_start;
350 
351         cb_info->users++;
352         /*
353          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
354          * svc_prepare_thread increments that. So we need to call svc_destroy
355          * on both success and failure so that the refcount is 1 when the
356          * thread exits.
357          */
358 err_net:
359         svc_destroy(serv);
360 err_create:
361         mutex_unlock(&nfs_callback_mutex);
362         return ret;
363 
364 err_start:
365         nfs_callback_down_net(minorversion, serv, net);
366         dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
367         goto err_net;
368 }
369 
370 /*
371  * Kill the callback thread if it's no longer being used.
372  */
373 void nfs_callback_down(int minorversion, struct net *net)
374 {
375         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
376 
377         mutex_lock(&nfs_callback_mutex);
378         nfs_callback_down_net(minorversion, cb_info->serv, net);
379         cb_info->users--;
380         if (cb_info->users == 0 && cb_info->task != NULL) {
381                 kthread_stop(cb_info->task);
382                 dprintk("nfs_callback_down: service stopped\n");
383                 svc_exit_thread(cb_info->rqst);
384                 dprintk("nfs_callback_down: service destroyed\n");
385                 cb_info->serv = NULL;
386                 cb_info->rqst = NULL;
387                 cb_info->task = NULL;
388         }
389         mutex_unlock(&nfs_callback_mutex);
390 }
391 
392 /* Boolean check of RPC_AUTH_GSS principal */
393 int
394 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
395 {
396         char *p = rqstp->rq_cred.cr_principal;
397 
398         if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
399                 return 1;
400 
401         /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
402         if (clp->cl_minorversion != 0)
403                 return 0;
404         /*
405          * It might just be a normal user principal, in which case
406          * userspace won't bother to tell us the name at all.
407          */
408         if (p == NULL)
409                 return 0;
410 
411         /*
412          * Did we get the acceptor from userland during the SETCLIENID
413          * negotiation?
414          */
415         if (clp->cl_acceptor)
416                 return !strcmp(p, clp->cl_acceptor);
417 
418         /*
419          * Otherwise try to verify it using the cl_hostname. Note that this
420          * doesn't work if a non-canonical hostname was used in the devname.
421          */
422 
423         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
424 
425         if (memcmp(p, "nfs@", 4) != 0)
426                 return 0;
427         p += 4;
428         if (strcmp(p, clp->cl_hostname) != 0)
429                 return 0;
430         return 1;
431 }
432 
433 /*
434  * pg_authenticate method for nfsv4 callback threads.
435  *
436  * The authflavor has been negotiated, so an incorrect flavor is a server
437  * bug. Deny packets with incorrect authflavor.
438  *
439  * All other checking done after NFS decoding where the nfs_client can be
440  * found in nfs4_callback_compound
441  */
442 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
443 {
444         switch (rqstp->rq_authop->flavour) {
445         case RPC_AUTH_NULL:
446                 if (rqstp->rq_proc != CB_NULL)
447                         return SVC_DENIED;
448                 break;
449         case RPC_AUTH_GSS:
450                 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
451                  if (svc_is_backchannel(rqstp))
452                         return SVC_DENIED;
453         }
454         return SVC_OK;
455 }
456 
457 /*
458  * Define NFS4 callback program
459  */
460 static struct svc_version *nfs4_callback_version[] = {
461         [1] = &nfs4_callback_version1,
462         [4] = &nfs4_callback_version4,
463 };
464 
465 static struct svc_stat nfs4_callback_stats;
466 
467 static struct svc_program nfs4_callback_program = {
468         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
469         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
470         .pg_vers = nfs4_callback_version,               /* version table */
471         .pg_name = "NFSv4 callback",                    /* service name */
472         .pg_class = "nfs",                              /* authentication class */
473         .pg_stats = &nfs4_callback_stats,
474         .pg_authenticate = nfs_callback_authenticate,
475 };
476 

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