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, id: nfs_net_id);
46
47 ret = svc_xprt_create(serv, xprt_name: "tcp", net, PF_INET,
48 port: 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, xprt_name: "tcp", net, PF_INET6,
57 port: 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, id: 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, id: 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 svc_get(serv: 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(error: -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(ptr: serv)) {
234 ret = PTR_ERR(ptr: 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 cb_info->serv = NULL;
250 svc_put(serv);
251err_create:
252 mutex_unlock(lock: &nfs_callback_mutex);
253 return ret;
254
255err_start:
256 nfs_callback_down_net(minorversion, serv, net);
257 dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
258 goto err_net;
259}
260
261/*
262 * Kill the callback thread if it's no longer being used.
263 */
264void nfs_callback_down(int minorversion, struct net *net)
265{
266 struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
267 struct svc_serv *serv;
268
269 mutex_lock(&nfs_callback_mutex);
270 serv = cb_info->serv;
271 nfs_callback_down_net(minorversion, serv, net);
272 cb_info->users--;
273 if (cb_info->users == 0) {
274 svc_get(serv);
275 svc_set_num_threads(serv, NULL, 0);
276 svc_put(serv);
277 dprintk("nfs_callback_down: service destroyed\n");
278 cb_info->serv = NULL;
279 }
280 mutex_unlock(lock: &nfs_callback_mutex);
281}
282
283/* Boolean check of RPC_AUTH_GSS principal */
284int
285check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
286{
287 char *p = rqstp->rq_cred.cr_principal;
288
289 if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
290 return 1;
291
292 /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
293 if (clp->cl_minorversion != 0)
294 return 0;
295 /*
296 * It might just be a normal user principal, in which case
297 * userspace won't bother to tell us the name at all.
298 */
299 if (p == NULL)
300 return 0;
301
302 /*
303 * Did we get the acceptor from userland during the SETCLIENID
304 * negotiation?
305 */
306 if (clp->cl_acceptor)
307 return !strcmp(p, clp->cl_acceptor);
308
309 /*
310 * Otherwise try to verify it using the cl_hostname. Note that this
311 * doesn't work if a non-canonical hostname was used in the devname.
312 */
313
314 /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
315
316 if (memcmp(p, q: "nfs@", size: 4) != 0)
317 return 0;
318 p += 4;
319 if (strcmp(p, clp->cl_hostname) != 0)
320 return 0;
321 return 1;
322}
323
324/*
325 * pg_authenticate method for nfsv4 callback threads.
326 *
327 * The authflavor has been negotiated, so an incorrect flavor is a server
328 * bug. Deny packets with incorrect authflavor.
329 *
330 * All other checking done after NFS decoding where the nfs_client can be
331 * found in nfs4_callback_compound
332 */
333static enum svc_auth_status nfs_callback_authenticate(struct svc_rqst *rqstp)
334{
335 rqstp->rq_auth_stat = rpc_autherr_badcred;
336
337 switch (rqstp->rq_authop->flavour) {
338 case RPC_AUTH_NULL:
339 if (rqstp->rq_proc != CB_NULL)
340 return SVC_DENIED;
341 break;
342 case RPC_AUTH_GSS:
343 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
344 if (svc_is_backchannel(rqstp))
345 return SVC_DENIED;
346 }
347
348 rqstp->rq_auth_stat = rpc_auth_ok;
349 return SVC_OK;
350}
351
352/*
353 * Define NFS4 callback program
354 */
355static const struct svc_version *nfs4_callback_version[] = {
356 [1] = &nfs4_callback_version1,
357 [4] = &nfs4_callback_version4,
358};
359
360static struct svc_stat nfs4_callback_stats;
361
362static struct svc_program nfs4_callback_program = {
363 .pg_prog = NFS4_CALLBACK, /* RPC service number */
364 .pg_nvers = ARRAY_SIZE(nfs4_callback_version), /* Number of entries */
365 .pg_vers = nfs4_callback_version, /* version table */
366 .pg_name = "NFSv4 callback", /* service name */
367 .pg_class = "nfs", /* authentication class */
368 .pg_stats = &nfs4_callback_stats,
369 .pg_authenticate = nfs_callback_authenticate,
370 .pg_init_request = svc_generic_init_request,
371 .pg_rpcbind_set = svc_generic_rpcbind_set,
372};
373

source code of linux/fs/nfs/callback.c