xref: /kernel/linux/linux-6.6/fs/nfs/callback.c (revision 62306a36) 
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/sunrpc/svcauth_gss.h>
21#include <linux/sunrpc/bc_xprt.h>
22
23#include <net/inet_sock.h>
24
25#include "nfs4_fs.h"
26#include "callback.h"
27#include "internal.h"
28#include "netns.h"
29
30#define NFSDBG_FACILITY NFSDBG_CALLBACK
31
32struct nfs_callback_data {
33	unsigned int users;
34	struct svc_serv *serv;
35};
36
37static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
38static DEFINE_MUTEX(nfs_callback_mutex);
39static struct svc_program nfs4_callback_program;
40
41static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
42{
43	const struct cred *cred = current_cred();
44	int ret;
45	struct nfs_net *nn = net_generic(net, nfs_net_id);
46
47	ret = svc_xprt_create(serv, "tcp", net, PF_INET,
48			      nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
49			      cred);
50	if (ret <= 0)
51		goto out_err;
52	nn->nfs_callback_tcpport = ret;
53	dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
54		nn->nfs_callback_tcpport, PF_INET, net->ns.inum);
55
56	ret = svc_xprt_create(serv, "tcp", net, PF_INET6,
57			      nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
58			      cred);
59	if (ret > 0) {
60		nn->nfs_callback_tcpport6 = ret;
61		dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
62			nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum);
63	} else if (ret != -EAFNOSUPPORT)
64		goto out_err;
65	return 0;
66
67out_err:
68	return (ret) ? ret : -ENOMEM;
69}
70
71/*
72 * This is the NFSv4 callback kernel thread.
73 */
74static int
75nfs4_callback_svc(void *vrqstp)
76{
77	struct svc_rqst *rqstp = vrqstp;
78
79	set_freezable();
80
81	while (!kthread_freezable_should_stop(NULL))
82		svc_recv(rqstp);
83
84	svc_exit_thread(rqstp);
85	return 0;
86}
87
88#if defined(CONFIG_NFS_V4_1)
89/*
90 * The callback service for NFSv4.1 callbacks
91 */
92static int
93nfs41_callback_svc(void *vrqstp)
94{
95	struct svc_rqst *rqstp = vrqstp;
96	struct svc_serv *serv = rqstp->rq_server;
97	struct rpc_rqst *req;
98	int error;
99	DEFINE_WAIT(wq);
100
101	set_freezable();
102
103	while (!kthread_freezable_should_stop(NULL)) {
104		prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_IDLE);
105		spin_lock_bh(&serv->sv_cb_lock);
106		if (!list_empty(&serv->sv_cb_list)) {
107			req = list_first_entry(&serv->sv_cb_list,
108					struct rpc_rqst, rq_bc_list);
109			list_del(&req->rq_bc_list);
110			spin_unlock_bh(&serv->sv_cb_lock);
111			finish_wait(&serv->sv_cb_waitq, &wq);
112			dprintk("Invoking bc_svc_process()\n");
113			error = bc_svc_process(serv, req, rqstp);
114			dprintk("bc_svc_process() returned w/ error code= %d\n",
115				error);
116		} else {
117			spin_unlock_bh(&serv->sv_cb_lock);
118			if (!kthread_should_stop())
119				schedule();
120			finish_wait(&serv->sv_cb_waitq, &wq);
121		}
122	}
123
124	svc_exit_thread(rqstp);
125	return 0;
126}
127
128static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
129		struct svc_serv *serv)
130{
131	if (minorversion)
132		/*
133		 * Save the svc_serv in the transport so that it can
134		 * be referenced when the session backchannel is initialized
135		 */
136		xprt->bc_serv = serv;
137}
138#else
139static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
140		struct svc_serv *serv)
141{
142}
143#endif /* CONFIG_NFS_V4_1 */
144
145static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
146				  struct svc_serv *serv)
147{
148	int nrservs = nfs_callback_nr_threads;
149	int ret;
150
151	nfs_callback_bc_serv(minorversion, xprt, serv);
152
153	if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
154		nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
155
156	if (serv->sv_nrthreads == nrservs)
157		return 0;
158
159	ret = svc_set_num_threads(serv, NULL, nrservs);
160	if (ret) {
161		svc_set_num_threads(serv, NULL, 0);
162		return ret;
163	}
164	dprintk("nfs_callback_up: service started\n");
165	return 0;
166}
167
168static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
169{
170	struct nfs_net *nn = net_generic(net, nfs_net_id);
171
172	if (--nn->cb_users[minorversion])
173		return;
174
175	dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
176	svc_xprt_destroy_all(serv, net);
177}
178
179static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
180			       struct net *net, struct rpc_xprt *xprt)
181{
182	struct nfs_net *nn = net_generic(net, nfs_net_id);
183	int ret;
184
185	if (nn->cb_users[minorversion]++)
186		return 0;
187
188	dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);
189
190	ret = svc_bind(serv, net);
191	if (ret < 0) {
192		printk(KERN_WARNING "NFS: bind callback service failed\n");
193		goto err_bind;
194	}
195
196	ret = 0;
197	if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
198		ret = nfs4_callback_up_net(serv, net);
199	else if (xprt->ops->bc_setup)
200		set_bc_enabled(serv);
201	else
202		ret = -EPROTONOSUPPORT;
203
204	if (ret < 0) {
205		printk(KERN_ERR "NFS: callback service start failed\n");
206		goto err_socks;
207	}
208	return 0;
209
210err_socks:
211	svc_rpcb_cleanup(serv, net);
212err_bind:
213	nn->cb_users[minorversion]--;
214	dprintk("NFS: Couldn't create callback socket: err = %d; "
215			"net = %x\n", ret, net->ns.inum);
216	return ret;
217}
218
219static struct svc_serv *nfs_callback_create_svc(int minorversion)
220{
221	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
222	int (*threadfn)(void *data);
223	struct svc_serv *serv;
224
225	/*
226	 * Check whether we're already up and running.
227	 */
228	if (cb_info->serv)
229		return svc_get(cb_info->serv);
230
231	/*
232	 * Sanity check: if there's no task,
233	 * we should be the first user ...
234	 */
235	if (cb_info->users)
236		printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
237			cb_info->users);
238
239	threadfn = nfs4_callback_svc;
240#if defined(CONFIG_NFS_V4_1)
241	if (minorversion)
242		threadfn = nfs41_callback_svc;
243#else
244	if (minorversion)
245		return ERR_PTR(-ENOTSUPP);
246#endif
247	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE,
248			  threadfn);
249	if (!serv) {
250		printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
251		return ERR_PTR(-ENOMEM);
252	}
253	cb_info->serv = serv;
254	/* As there is only one thread we need to over-ride the
255	 * default maximum of 80 connections
256	 */
257	serv->sv_maxconn = 1024;
258	dprintk("nfs_callback_create_svc: service created\n");
259	return serv;
260}
261
262/*
263 * Bring up the callback thread if it is not already up.
264 */
265int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
266{
267	struct svc_serv *serv;
268	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
269	int ret;
270	struct net *net = xprt->xprt_net;
271
272	mutex_lock(&nfs_callback_mutex);
273
274	serv = nfs_callback_create_svc(minorversion);
275	if (IS_ERR(serv)) {
276		ret = PTR_ERR(serv);
277		goto err_create;
278	}
279
280	ret = nfs_callback_up_net(minorversion, serv, net, xprt);
281	if (ret < 0)
282		goto err_net;
283
284	ret = nfs_callback_start_svc(minorversion, xprt, serv);
285	if (ret < 0)
286		goto err_start;
287
288	cb_info->users++;
289err_net:
290	if (!cb_info->users)
291		cb_info->serv = NULL;
292	svc_put(serv);
293err_create:
294	mutex_unlock(&nfs_callback_mutex);
295	return ret;
296
297err_start:
298	nfs_callback_down_net(minorversion, serv, net);
299	dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
300	goto err_net;
301}
302
303/*
304 * Kill the callback thread if it's no longer being used.
305 */
306void nfs_callback_down(int minorversion, struct net *net)
307{
308	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
309	struct svc_serv *serv;
310
311	mutex_lock(&nfs_callback_mutex);
312	serv = cb_info->serv;
313	nfs_callback_down_net(minorversion, serv, net);
314	cb_info->users--;
315	if (cb_info->users == 0) {
316		svc_get(serv);
317		svc_set_num_threads(serv, NULL, 0);
318		svc_put(serv);
319		dprintk("nfs_callback_down: service destroyed\n");
320		cb_info->serv = NULL;
321	}
322	mutex_unlock(&nfs_callback_mutex);
323}
324
325/* Boolean check of RPC_AUTH_GSS principal */
326int
327check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
328{
329	char *p = rqstp->rq_cred.cr_principal;
330
331	if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
332		return 1;
333
334	/* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
335	if (clp->cl_minorversion != 0)
336		return 0;
337	/*
338	 * It might just be a normal user principal, in which case
339	 * userspace won't bother to tell us the name at all.
340	 */
341	if (p == NULL)
342		return 0;
343
344	/*
345	 * Did we get the acceptor from userland during the SETCLIENID
346	 * negotiation?
347	 */
348	if (clp->cl_acceptor)
349		return !strcmp(p, clp->cl_acceptor);
350
351	/*
352	 * Otherwise try to verify it using the cl_hostname. Note that this
353	 * doesn't work if a non-canonical hostname was used in the devname.
354	 */
355
356	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
357
358	if (memcmp(p, "nfs@", 4) != 0)
359		return 0;
360	p += 4;
361	if (strcmp(p, clp->cl_hostname) != 0)
362		return 0;
363	return 1;
364}
365
366/*
367 * pg_authenticate method for nfsv4 callback threads.
368 *
369 * The authflavor has been negotiated, so an incorrect flavor is a server
370 * bug. Deny packets with incorrect authflavor.
371 *
372 * All other checking done after NFS decoding where the nfs_client can be
373 * found in nfs4_callback_compound
374 */
375static enum svc_auth_status nfs_callback_authenticate(struct svc_rqst *rqstp)
376{
377	rqstp->rq_auth_stat = rpc_autherr_badcred;
378
379	switch (rqstp->rq_authop->flavour) {
380	case RPC_AUTH_NULL:
381		if (rqstp->rq_proc != CB_NULL)
382			return SVC_DENIED;
383		break;
384	case RPC_AUTH_GSS:
385		/* No RPC_AUTH_GSS support yet in NFSv4.1 */
386		 if (svc_is_backchannel(rqstp))
387			return SVC_DENIED;
388	}
389
390	rqstp->rq_auth_stat = rpc_auth_ok;
391	return SVC_OK;
392}
393
394/*
395 * Define NFS4 callback program
396 */
397static const struct svc_version *nfs4_callback_version[] = {
398	[1] = &nfs4_callback_version1,
399	[4] = &nfs4_callback_version4,
400};
401
402static struct svc_stat nfs4_callback_stats;
403
404static struct svc_program nfs4_callback_program = {
405	.pg_prog = NFS4_CALLBACK,			/* RPC service number */
406	.pg_nvers = ARRAY_SIZE(nfs4_callback_version),	/* Number of entries */
407	.pg_vers = nfs4_callback_version,		/* version table */
408	.pg_name = "NFSv4 callback",			/* service name */
409	.pg_class = "nfs",				/* authentication class */
410	.pg_stats = &nfs4_callback_stats,
411	.pg_authenticate = nfs_callback_authenticate,
412	.pg_init_request = svc_generic_init_request,
413	.pg_rpcbind_set	= svc_generic_rpcbind_set,
414};
415