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