callback.c

  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);
 85
 86	svc_exit_thread(rqstp);
 87	return 0;
 88}
 89
 90#if defined(CONFIG_NFS_V4_1)
 91static 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
102static 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
108static 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
131static 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
142static 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
173err:
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	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 */
219int 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++;
243err_net:
244	if (!cb_info->users) {
245		svc_set_num_threads(cb_info->serv, NULL, 0);
246		svc_destroy(&cb_info->serv);
247	}
248err_create:
249	mutex_unlock(&nfs_callback_mutex);
250	return ret;
251
252err_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 */
261void nfs_callback_down(int minorversion, struct net *net, struct rpc_xprt *xprt)
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		xprt_svc_destroy_nullify_bc(xprt, &cb_info->serv);
274	}
275	mutex_unlock(&nfs_callback_mutex);
276}
277
278/* Boolean check of RPC_AUTH_GSS principal */
279int
280check_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 */
328static 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 */
350static const struct svc_version *nfs4_callback_version[] = {
351	[1] = &nfs4_callback_version1,
352	[4] = &nfs4_callback_version4,
353};
354
355static 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};