xref: /openbmc/linux/fs/nfs/callback.c (revision 9cfc5c90) 
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