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Linux/fs/nfs/callback.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * linux/fs/nfs/callback.c
  4  *
  5  * Copyright (C) 2004 Trond Myklebust
  6  *
  7  * NFSv4 callback handling
  8  */
  9 
 10 #include <linux/completion.h>
 11 #include <linux/ip.h>
 12 #include <linux/module.h>
 13 #include <linux/sched/signal.h>
 14 #include <linux/sunrpc/svc.h>
 15 #include <linux/sunrpc/svcsock.h>
 16 #include <linux/nfs_fs.h>
 17 #include <linux/errno.h>
 18 #include <linux/mutex.h>
 19 #include <linux/freezer.h>
 20 #include <linux/kthread.h>
 21 #include <linux/sunrpc/svcauth_gss.h>
 22 #include <linux/sunrpc/bc_xprt.h>
 23 
 24 #include <net/inet_sock.h>
 25 
 26 #include "nfs4_fs.h"
 27 #include "callback.h"
 28 #include "internal.h"
 29 #include "netns.h"
 30 
 31 #define NFSDBG_FACILITY NFSDBG_CALLBACK
 32 
 33 struct nfs_callback_data {
 34         unsigned int users;
 35         struct svc_serv *serv;
 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 %x)\n",
 53                 nn->nfs_callback_tcpport, PF_INET, net->ns.inum);
 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 %x\n",
 60                         nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum);
 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_freezable_should_stop(NULL)) {
 81 
 82                 if (signal_pending(current))
 83                         flush_signals(current);
 84                 /*
 85                  * Listen for a request on the socket
 86                  */
 87                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
 88                 if (err == -EAGAIN || err == -EINTR)
 89                         continue;
 90                 svc_process(rqstp);
 91         }
 92         svc_exit_thread(rqstp);
 93         module_put_and_exit(0);
 94         return 0;
 95 }
 96 
 97 #if defined(CONFIG_NFS_V4_1)
 98 /*
 99  * The callback service for NFSv4.1 callbacks
100  */
101 static int
102 nfs41_callback_svc(void *vrqstp)
103 {
104         struct svc_rqst *rqstp = vrqstp;
105         struct svc_serv *serv = rqstp->rq_server;
106         struct rpc_rqst *req;
107         int error;
108         DEFINE_WAIT(wq);
109 
110         set_freezable();
111 
112         while (!kthread_freezable_should_stop(NULL)) {
113 
114                 if (signal_pending(current))
115                         flush_signals(current);
116 
117                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
118                 spin_lock_bh(&serv->sv_cb_lock);
119                 if (!list_empty(&serv->sv_cb_list)) {
120                         req = list_first_entry(&serv->sv_cb_list,
121                                         struct rpc_rqst, rq_bc_list);
122                         list_del(&req->rq_bc_list);
123                         spin_unlock_bh(&serv->sv_cb_lock);
124                         finish_wait(&serv->sv_cb_waitq, &wq);
125                         dprintk("Invoking bc_svc_process()\n");
126                         error = bc_svc_process(serv, req, rqstp);
127                         dprintk("bc_svc_process() returned w/ error code= %d\n",
128                                 error);
129                 } else {
130                         spin_unlock_bh(&serv->sv_cb_lock);
131                         if (!kthread_should_stop())
132                                 schedule();
133                         finish_wait(&serv->sv_cb_waitq, &wq);
134                 }
135         }
136         svc_exit_thread(rqstp);
137         module_put_and_exit(0);
138         return 0;
139 }
140 
141 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
142                 struct svc_serv *serv)
143 {
144         if (minorversion)
145                 /*
146                  * Save the svc_serv in the transport so that it can
147                  * be referenced when the session backchannel is initialized
148                  */
149                 xprt->bc_serv = serv;
150 }
151 #else
152 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
153                 struct svc_serv *serv)
154 {
155 }
156 #endif /* CONFIG_NFS_V4_1 */
157 
158 static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
159                                   struct svc_serv *serv)
160 {
161         int nrservs = nfs_callback_nr_threads;
162         int ret;
163 
164         nfs_callback_bc_serv(minorversion, xprt, serv);
165 
166         if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
167                 nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
168 
169         if (serv->sv_nrthreads-1 == nrservs)
170                 return 0;
171 
172         ret = serv->sv_ops->svo_setup(serv, NULL, nrservs);
173         if (ret) {
174                 serv->sv_ops->svo_setup(serv, NULL, 0);
175                 return ret;
176         }
177         dprintk("nfs_callback_up: service started\n");
178         return 0;
179 }
180 
181 static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
182 {
183         struct nfs_net *nn = net_generic(net, nfs_net_id);
184 
185         if (--nn->cb_users[minorversion])
186                 return;
187 
188         dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
189         svc_shutdown_net(serv, net);
190 }
191 
192 static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
193                                struct net *net, struct rpc_xprt *xprt)
194 {
195         struct nfs_net *nn = net_generic(net, nfs_net_id);
196         int ret;
197 
198         if (nn->cb_users[minorversion]++)
199                 return 0;
200 
201         dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);
202 
203         ret = svc_bind(serv, net);
204         if (ret < 0) {
205                 printk(KERN_WARNING "NFS: bind callback service failed\n");
206                 goto err_bind;
207         }
208 
209         ret = -EPROTONOSUPPORT;
210         if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
211                 ret = nfs4_callback_up_net(serv, net);
212         else if (xprt->ops->bc_up)
213                 ret = xprt->ops->bc_up(serv, net);
214 
215         if (ret < 0) {
216                 printk(KERN_ERR "NFS: callback service start failed\n");
217                 goto err_socks;
218         }
219         return 0;
220 
221 err_socks:
222         svc_rpcb_cleanup(serv, net);
223 err_bind:
224         nn->cb_users[minorversion]--;
225         dprintk("NFS: Couldn't create callback socket: err = %d; "
226                         "net = %x\n", ret, net->ns.inum);
227         return ret;
228 }
229 
230 static const struct svc_serv_ops nfs40_cb_sv_ops = {
231         .svo_function           = nfs4_callback_svc,
232         .svo_enqueue_xprt       = svc_xprt_do_enqueue,
233         .svo_setup              = svc_set_num_threads_sync,
234         .svo_module             = THIS_MODULE,
235 };
236 #if defined(CONFIG_NFS_V4_1)
237 static const struct svc_serv_ops nfs41_cb_sv_ops = {
238         .svo_function           = nfs41_callback_svc,
239         .svo_enqueue_xprt       = svc_xprt_do_enqueue,
240         .svo_setup              = svc_set_num_threads_sync,
241         .svo_module             = THIS_MODULE,
242 };
243 
244 static const struct svc_serv_ops *nfs4_cb_sv_ops[] = {
245         [0] = &nfs40_cb_sv_ops,
246         [1] = &nfs41_cb_sv_ops,
247 };
248 #else
249 static const struct svc_serv_ops *nfs4_cb_sv_ops[] = {
250         [0] = &nfs40_cb_sv_ops,
251         [1] = NULL,
252 };
253 #endif
254 
255 static struct svc_serv *nfs_callback_create_svc(int minorversion)
256 {
257         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
258         const struct svc_serv_ops *sv_ops;
259         struct svc_serv *serv;
260 
261         /*
262          * Check whether we're already up and running.
263          */
264         if (cb_info->serv) {
265                 /*
266                  * Note: increase service usage, because later in case of error
267                  * svc_destroy() will be called.
268                  */
269                 svc_get(cb_info->serv);
270                 return cb_info->serv;
271         }
272 
273         switch (minorversion) {
274         case 0:
275                 sv_ops = nfs4_cb_sv_ops[0];
276                 break;
277         default:
278                 sv_ops = nfs4_cb_sv_ops[1];
279         }
280 
281         if (sv_ops == NULL)
282                 return ERR_PTR(-ENOTSUPP);
283 
284         /*
285          * Sanity check: if there's no task,
286          * we should be the first user ...
287          */
288         if (cb_info->users)
289                 printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
290                         cb_info->users);
291 
292         serv = svc_create_pooled(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, sv_ops);
293         if (!serv) {
294                 printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
295                 return ERR_PTR(-ENOMEM);
296         }
297         cb_info->serv = serv;
298         /* As there is only one thread we need to over-ride the
299          * default maximum of 80 connections
300          */
301         serv->sv_maxconn = 1024;
302         dprintk("nfs_callback_create_svc: service created\n");
303         return serv;
304 }
305 
306 /*
307  * Bring up the callback thread if it is not already up.
308  */
309 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
310 {
311         struct svc_serv *serv;
312         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
313         int ret;
314         struct net *net = xprt->xprt_net;
315 
316         mutex_lock(&nfs_callback_mutex);
317 
318         serv = nfs_callback_create_svc(minorversion);
319         if (IS_ERR(serv)) {
320                 ret = PTR_ERR(serv);
321                 goto err_create;
322         }
323 
324         ret = nfs_callback_up_net(minorversion, serv, net, xprt);
325         if (ret < 0)
326                 goto err_net;
327 
328         ret = nfs_callback_start_svc(minorversion, xprt, serv);
329         if (ret < 0)
330                 goto err_start;
331 
332         cb_info->users++;
333         /*
334          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
335          * svc_prepare_thread increments that. So we need to call svc_destroy
336          * on both success and failure so that the refcount is 1 when the
337          * thread exits.
338          */
339 err_net:
340         if (!cb_info->users)
341                 cb_info->serv = NULL;
342         svc_destroy(serv);
343 err_create:
344         mutex_unlock(&nfs_callback_mutex);
345         return ret;
346 
347 err_start:
348         nfs_callback_down_net(minorversion, serv, net);
349         dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
350         goto err_net;
351 }
352 
353 /*
354  * Kill the callback thread if it's no longer being used.
355  */
356 void nfs_callback_down(int minorversion, struct net *net)
357 {
358         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
359         struct svc_serv *serv;
360 
361         mutex_lock(&nfs_callback_mutex);
362         serv = cb_info->serv;
363         nfs_callback_down_net(minorversion, serv, net);
364         cb_info->users--;
365         if (cb_info->users == 0) {
366                 svc_get(serv);
367                 serv->sv_ops->svo_setup(serv, NULL, 0);
368                 svc_destroy(serv);
369                 dprintk("nfs_callback_down: service destroyed\n");
370                 cb_info->serv = NULL;
371         }
372         mutex_unlock(&nfs_callback_mutex);
373 }
374 
375 /* Boolean check of RPC_AUTH_GSS principal */
376 int
377 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
378 {
379         char *p = rqstp->rq_cred.cr_principal;
380 
381         if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
382                 return 1;
383 
384         /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
385         if (clp->cl_minorversion != 0)
386                 return 0;
387         /*
388          * It might just be a normal user principal, in which case
389          * userspace won't bother to tell us the name at all.
390          */
391         if (p == NULL)
392                 return 0;
393 
394         /*
395          * Did we get the acceptor from userland during the SETCLIENID
396          * negotiation?
397          */
398         if (clp->cl_acceptor)
399                 return !strcmp(p, clp->cl_acceptor);
400 
401         /*
402          * Otherwise try to verify it using the cl_hostname. Note that this
403          * doesn't work if a non-canonical hostname was used in the devname.
404          */
405 
406         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
407 
408         if (memcmp(p, "nfs@", 4) != 0)
409                 return 0;
410         p += 4;
411         if (strcmp(p, clp->cl_hostname) != 0)
412                 return 0;
413         return 1;
414 }
415 
416 /*
417  * pg_authenticate method for nfsv4 callback threads.
418  *
419  * The authflavor has been negotiated, so an incorrect flavor is a server
420  * bug. Deny packets with incorrect authflavor.
421  *
422  * All other checking done after NFS decoding where the nfs_client can be
423  * found in nfs4_callback_compound
424  */
425 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
426 {
427         switch (rqstp->rq_authop->flavour) {
428         case RPC_AUTH_NULL:
429                 if (rqstp->rq_proc != CB_NULL)
430                         return SVC_DENIED;
431                 break;
432         case RPC_AUTH_GSS:
433                 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
434                  if (svc_is_backchannel(rqstp))
435                         return SVC_DENIED;
436         }
437         return SVC_OK;
438 }
439 
440 /*
441  * Define NFS4 callback program
442  */
443 static const struct svc_version *nfs4_callback_version[] = {
444         [1] = &nfs4_callback_version1,
445         [4] = &nfs4_callback_version4,
446 };
447 
448 static struct svc_stat nfs4_callback_stats;
449 
450 static struct svc_program nfs4_callback_program = {
451         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
452         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
453         .pg_vers = nfs4_callback_version,               /* version table */
454         .pg_name = "NFSv4 callback",                    /* service name */
455         .pg_class = "nfs",                              /* authentication class */
456         .pg_stats = &nfs4_callback_stats,
457         .pg_authenticate = nfs_callback_authenticate,
458 };
459 

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