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