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 (!svc_thread_should_stop(rqstp))
82		svc_recv(rqstp);
83
84	svc_exit_thread(rqstp);
85	return 0;
86}
87
88#if defined(CONFIG_NFS_V4_1)
89static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
90		struct svc_serv *serv)
91{
92	if (minorversion)
93		/*
94		 * Save the svc_serv in the transport so that it can
95		 * be referenced when the session backchannel is initialized
96		 */
97		xprt->bc_serv = serv;
98}
99#else
100static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
101		struct svc_serv *serv)
102{
103}
104#endif /* CONFIG_NFS_V4_1 */
105
106static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
107				  struct svc_serv *serv)
108{
109	int nrservs = nfs_callback_nr_threads;
110	int ret;
111
112	nfs_callback_bc_serv(minorversion, xprt, serv);
113
114	if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
115		nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
116
117	if (serv->sv_nrthreads == nrservs)
118		return 0;
119
120	ret = svc_set_num_threads(serv, NULL, nrservs);
121	if (ret) {
122		svc_set_num_threads(serv, NULL, 0);
123		return ret;
124	}
125	dprintk("nfs_callback_up: service started\n");
126	return 0;
127}
128
129static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
130{
131	struct nfs_net *nn = net_generic(net, nfs_net_id);
132
133	if (--nn->cb_users[minorversion])
134		return;
135
136	dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
137	svc_xprt_destroy_all(serv, net);
138}
139
140static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
141			       struct net *net, struct rpc_xprt *xprt)
142{
143	struct nfs_net *nn = net_generic(net, nfs_net_id);
144	int ret;
145
146	if (nn->cb_users[minorversion]++)
147		return 0;
148
149	dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);
150
151	ret = svc_bind(serv, net);
152	if (ret < 0) {
153		printk(KERN_WARNING "NFS: bind callback service failed\n");
154		goto err_bind;
155	}
156
157	ret = 0;
158	if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
159		ret = nfs4_callback_up_net(serv, net);
160	else if (xprt->ops->bc_setup)
161		set_bc_enabled(serv);
162	else
163		ret = -EPROTONOSUPPORT;
164
165	if (ret < 0) {
166		printk(KERN_ERR "NFS: callback service start failed\n");
167		goto err_socks;
168	}
169	return 0;
170
171err_socks:
172	svc_rpcb_cleanup(serv, net);
173err_bind:
174	nn->cb_users[minorversion]--;
175	dprintk("NFS: Couldn't create callback socket: err = %d; "
176			"net = %x\n", ret, net->ns.inum);
177	return ret;
178}
179
180static struct svc_serv *nfs_callback_create_svc(int minorversion)
181{
182	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
183	int (*threadfn)(void *data);
184	struct svc_serv *serv;
185
186	/*
187	 * Check whether we're already up and running.
188	 */
189	if (cb_info->serv)
190		return cb_info->serv;
191
192	/*
193	 * Sanity check: if there's no task,
194	 * we should be the first user ...
195	 */
196	if (cb_info->users)
197		printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
198			cb_info->users);
199
200	threadfn = nfs4_callback_svc;
201#if !defined(CONFIG_NFS_V4_1)
202	if (minorversion)
203		return ERR_PTR(-ENOTSUPP);
204#endif
205	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE,
206			  threadfn);
207	if (!serv) {
208		printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
209		return ERR_PTR(-ENOMEM);
210	}
211	cb_info->serv = serv;
212	/* As there is only one thread we need to over-ride the
213	 * default maximum of 80 connections
214	 */
215	serv->sv_maxconn = 1024;
216	dprintk("nfs_callback_create_svc: service created\n");
217	return serv;
218}
219
220/*
221 * Bring up the callback thread if it is not already up.
222 */
223int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
224{
225	struct svc_serv *serv;
226	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
227	int ret;
228	struct net *net = xprt->xprt_net;
229
230	mutex_lock(&nfs_callback_mutex);
231
232	serv = nfs_callback_create_svc(minorversion);
233	if (IS_ERR(serv)) {
234		ret = PTR_ERR(serv);
235		goto err_create;
236	}
237
238	ret = nfs_callback_up_net(minorversion, serv, net, xprt);
239	if (ret < 0)
240		goto err_net;
241
242	ret = nfs_callback_start_svc(minorversion, xprt, serv);
243	if (ret < 0)
244		goto err_start;
245
246	cb_info->users++;
247err_net:
248	if (!cb_info->users) {
249		svc_set_num_threads(cb_info->serv, NULL, 0);
250		svc_destroy(&cb_info->serv);
251	}
252err_create:
253	mutex_unlock(&nfs_callback_mutex);
254	return ret;
255
256err_start:
257	nfs_callback_down_net(minorversion, serv, net);
258	dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
259	goto err_net;
260}
261
262/*
263 * Kill the callback thread if it's no longer being used.
264 */
265void nfs_callback_down(int minorversion, struct net *net)
266{
267	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
268	struct svc_serv *serv;
269
270	mutex_lock(&nfs_callback_mutex);
271	serv = cb_info->serv;
272	nfs_callback_down_net(minorversion, serv, net);
273	cb_info->users--;
274	if (cb_info->users == 0) {
275		svc_set_num_threads(serv, NULL, 0);
276		dprintk("nfs_callback_down: service destroyed\n");
277		svc_destroy(&cb_info->serv);
278	}
279	mutex_unlock(&nfs_callback_mutex);
280}
281
282/* Boolean check of RPC_AUTH_GSS principal */
283int
284check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
285{
286	char *p = rqstp->rq_cred.cr_principal;
287
288	if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
289		return 1;
290
291	/* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
292	if (clp->cl_minorversion != 0)
293		return 0;
294	/*
295	 * It might just be a normal user principal, in which case
296	 * userspace won't bother to tell us the name at all.
297	 */
298	if (p == NULL)
299		return 0;
300
301	/*
302	 * Did we get the acceptor from userland during the SETCLIENID
303	 * negotiation?
304	 */
305	if (clp->cl_acceptor)
306		return !strcmp(p, clp->cl_acceptor);
307
308	/*
309	 * Otherwise try to verify it using the cl_hostname. Note that this
310	 * doesn't work if a non-canonical hostname was used in the devname.
311	 */
312
313	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
314
315	if (memcmp(p, "nfs@", 4) != 0)
316		return 0;
317	p += 4;
318	if (strcmp(p, clp->cl_hostname) != 0)
319		return 0;
320	return 1;
321}
322
323/*
324 * pg_authenticate method for nfsv4 callback threads.
325 *
326 * The authflavor has been negotiated, so an incorrect flavor is a server
327 * bug. Deny packets with incorrect authflavor.
328 *
329 * All other checking done after NFS decoding where the nfs_client can be
330 * found in nfs4_callback_compound
331 */
332static enum svc_auth_status nfs_callback_authenticate(struct svc_rqst *rqstp)
333{
334	rqstp->rq_auth_stat = rpc_autherr_badcred;
335
336	switch (rqstp->rq_authop->flavour) {
337	case RPC_AUTH_NULL:
338		if (rqstp->rq_proc != CB_NULL)
339			return SVC_DENIED;
340		break;
341	case RPC_AUTH_GSS:
342		/* No RPC_AUTH_GSS support yet in NFSv4.1 */
343		 if (svc_is_backchannel(rqstp))
344			return SVC_DENIED;
345	}
346
347	rqstp->rq_auth_stat = rpc_auth_ok;
348	return SVC_OK;
349}
350
351/*
352 * Define NFS4 callback program
353 */
354static const struct svc_version *nfs4_callback_version[] = {
355	[1] = &nfs4_callback_version1,
356	[4] = &nfs4_callback_version4,
357};
358
359static struct svc_program nfs4_callback_program = {
360	.pg_prog = NFS4_CALLBACK,			/* RPC service number */
361	.pg_nvers = ARRAY_SIZE(nfs4_callback_version),	/* Number of entries */
362	.pg_vers = nfs4_callback_version,		/* version table */
363	.pg_name = "NFSv4 callback",			/* service name */
364	.pg_class = "nfs",				/* authentication class */
365	.pg_authenticate = nfs_callback_authenticate,
366	.pg_init_request = svc_generic_init_request,
367	.pg_rpcbind_set	= svc_generic_rpcbind_set,
368};
369