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
32 struct nfs_callback_data {
33 unsigned int users;
34 struct svc_serv *serv;
35 };
36
37 static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
38 static DEFINE_MUTEX(nfs_callback_mutex);
39 static struct svc_program nfs4_callback_program;
40
nfs4_callback_up_net(struct svc_serv * serv,struct net * net)41 static 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
67 out_err:
68 return (ret) ? ret : -ENOMEM;
69 }
70
71 /*
72 * This is the NFSv4 callback kernel thread.
73 */
74 static int
nfs4_callback_svc(void * vrqstp)75 nfs4_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 */
92 static int
nfs41_callback_svc(void * vrqstp)93 nfs41_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
nfs_callback_bc_serv(u32 minorversion,struct rpc_xprt * xprt,struct svc_serv * serv)128 static 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
nfs_callback_bc_serv(u32 minorversion,struct rpc_xprt * xprt,struct svc_serv * serv)139 static 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
nfs_callback_start_svc(int minorversion,struct rpc_xprt * xprt,struct svc_serv * serv)145 static 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
nfs_callback_down_net(u32 minorversion,struct svc_serv * serv,struct net * net)168 static 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
nfs_callback_up_net(int minorversion,struct svc_serv * serv,struct net * net,struct rpc_xprt * xprt)179 static 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
210 err_socks:
211 svc_rpcb_cleanup(serv, net);
212 err_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
nfs_callback_create_svc(int minorversion)219 static 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 */
nfs_callback_up(u32 minorversion,struct rpc_xprt * xprt)265 int 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++;
289 err_net:
290 if (!cb_info->users)
291 cb_info->serv = NULL;
292 svc_put(serv);
293 err_create:
294 mutex_unlock(&nfs_callback_mutex);
295 return ret;
296
297 err_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 */
nfs_callback_down(int minorversion,struct net * net)306 void 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 */
326 int
check_gss_callback_principal(struct nfs_client * clp,struct svc_rqst * rqstp)327 check_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 */
nfs_callback_authenticate(struct svc_rqst * rqstp)375 static 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 */
397 static const struct svc_version *nfs4_callback_version[] = {
398 [1] = &nfs4_callback_version1,
399 [4] = &nfs4_callback_version4,
400 };
401
402 static struct svc_stat nfs4_callback_stats;
403
404 static 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