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/kthread.h> 21 #include <linux/sunrpc/svcauth_gss.h> 22 #include <linux/sunrpc/bc_xprt.h> 23 24 #include <net/inet_sock.h> 25 26 #include "nfs4_fs.h" 27 #include "callback.h" 28 #include "internal.h" 29 #include "netns.h" 30 31 #define NFSDBG_FACILITY NFSDBG_CALLBACK 32 33 struct nfs_callback_data { 34 unsigned int users; 35 struct svc_serv *serv; 36 }; 37 38 static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1]; 39 static DEFINE_MUTEX(nfs_callback_mutex); 40 static struct svc_program nfs4_callback_program; 41 42 static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net) 43 { 44 const struct cred *cred = current_cred(); 45 int ret; 46 struct nfs_net *nn = net_generic(net, nfs_net_id); 47 48 ret = svc_create_xprt(serv, "tcp", net, PF_INET, 49 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS, 50 cred); 51 if (ret <= 0) 52 goto out_err; 53 nn->nfs_callback_tcpport = ret; 54 dprintk("NFS: Callback listener port = %u (af %u, net %x)\n", 55 nn->nfs_callback_tcpport, PF_INET, net->ns.inum); 56 57 ret = svc_create_xprt(serv, "tcp", net, PF_INET6, 58 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS, 59 cred); 60 if (ret > 0) { 61 nn->nfs_callback_tcpport6 = ret; 62 dprintk("NFS: Callback listener port = %u (af %u, net %x)\n", 63 nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum); 64 } else if (ret != -EAFNOSUPPORT) 65 goto out_err; 66 return 0; 67 68 out_err: 69 return (ret) ? ret : -ENOMEM; 70 } 71 72 /* 73 * This is the NFSv4 callback kernel thread. 74 */ 75 static int 76 nfs4_callback_svc(void *vrqstp) 77 { 78 int err; 79 struct svc_rqst *rqstp = vrqstp; 80 81 set_freezable(); 82 83 while (!kthread_freezable_should_stop(NULL)) { 84 85 if (signal_pending(current)) 86 flush_signals(current); 87 /* 88 * Listen for a request on the socket 89 */ 90 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT); 91 if (err == -EAGAIN || err == -EINTR) 92 continue; 93 svc_process(rqstp); 94 } 95 svc_exit_thread(rqstp); 96 module_put_and_exit(0); 97 return 0; 98 } 99 100 #if defined(CONFIG_NFS_V4_1) 101 /* 102 * The callback service for NFSv4.1 callbacks 103 */ 104 static int 105 nfs41_callback_svc(void *vrqstp) 106 { 107 struct svc_rqst *rqstp = vrqstp; 108 struct svc_serv *serv = rqstp->rq_server; 109 struct rpc_rqst *req; 110 int error; 111 DEFINE_WAIT(wq); 112 113 set_freezable(); 114 115 while (!kthread_freezable_should_stop(NULL)) { 116 117 if (signal_pending(current)) 118 flush_signals(current); 119 120 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE); 121 spin_lock_bh(&serv->sv_cb_lock); 122 if (!list_empty(&serv->sv_cb_list)) { 123 req = list_first_entry(&serv->sv_cb_list, 124 struct rpc_rqst, rq_bc_list); 125 list_del(&req->rq_bc_list); 126 spin_unlock_bh(&serv->sv_cb_lock); 127 finish_wait(&serv->sv_cb_waitq, &wq); 128 dprintk("Invoking bc_svc_process()\n"); 129 error = bc_svc_process(serv, req, rqstp); 130 dprintk("bc_svc_process() returned w/ error code= %d\n", 131 error); 132 } else { 133 spin_unlock_bh(&serv->sv_cb_lock); 134 if (!kthread_should_stop()) 135 schedule(); 136 finish_wait(&serv->sv_cb_waitq, &wq); 137 } 138 } 139 svc_exit_thread(rqstp); 140 module_put_and_exit(0); 141 return 0; 142 } 143 144 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt, 145 struct svc_serv *serv) 146 { 147 if (minorversion) 148 /* 149 * Save the svc_serv in the transport so that it can 150 * be referenced when the session backchannel is initialized 151 */ 152 xprt->bc_serv = serv; 153 } 154 #else 155 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt, 156 struct svc_serv *serv) 157 { 158 } 159 #endif /* CONFIG_NFS_V4_1 */ 160 161 static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt, 162 struct svc_serv *serv) 163 { 164 int nrservs = nfs_callback_nr_threads; 165 int ret; 166 167 nfs_callback_bc_serv(minorversion, xprt, serv); 168 169 if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS) 170 nrservs = NFS4_MIN_NR_CALLBACK_THREADS; 171 172 if (serv->sv_nrthreads-1 == nrservs) 173 return 0; 174 175 ret = serv->sv_ops->svo_setup(serv, NULL, nrservs); 176 if (ret) { 177 serv->sv_ops->svo_setup(serv, NULL, 0); 178 return ret; 179 } 180 dprintk("nfs_callback_up: service started\n"); 181 return 0; 182 } 183 184 static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net) 185 { 186 struct nfs_net *nn = net_generic(net, nfs_net_id); 187 188 if (--nn->cb_users[minorversion]) 189 return; 190 191 dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum); 192 svc_shutdown_net(serv, net); 193 } 194 195 static int nfs_callback_up_net(int minorversion, struct svc_serv *serv, 196 struct net *net, struct rpc_xprt *xprt) 197 { 198 struct nfs_net *nn = net_generic(net, nfs_net_id); 199 int ret; 200 201 if (nn->cb_users[minorversion]++) 202 return 0; 203 204 dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum); 205 206 ret = svc_bind(serv, net); 207 if (ret < 0) { 208 printk(KERN_WARNING "NFS: bind callback service failed\n"); 209 goto err_bind; 210 } 211 212 ret = 0; 213 if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0) 214 ret = nfs4_callback_up_net(serv, net); 215 else if (xprt->ops->bc_setup) 216 set_bc_enabled(serv); 217 else 218 ret = -EPROTONOSUPPORT; 219 220 if (ret < 0) { 221 printk(KERN_ERR "NFS: callback service start failed\n"); 222 goto err_socks; 223 } 224 return 0; 225 226 err_socks: 227 svc_rpcb_cleanup(serv, net); 228 err_bind: 229 nn->cb_users[minorversion]--; 230 dprintk("NFS: Couldn't create callback socket: err = %d; " 231 "net = %x\n", ret, net->ns.inum); 232 return ret; 233 } 234 235 static const struct svc_serv_ops nfs40_cb_sv_ops = { 236 .svo_function = nfs4_callback_svc, 237 .svo_enqueue_xprt = svc_xprt_do_enqueue, 238 .svo_setup = svc_set_num_threads_sync, 239 .svo_module = THIS_MODULE, 240 }; 241 #if defined(CONFIG_NFS_V4_1) 242 static const struct svc_serv_ops nfs41_cb_sv_ops = { 243 .svo_function = nfs41_callback_svc, 244 .svo_enqueue_xprt = svc_xprt_do_enqueue, 245 .svo_setup = svc_set_num_threads_sync, 246 .svo_module = THIS_MODULE, 247 }; 248 249 static const struct svc_serv_ops *nfs4_cb_sv_ops[] = { 250 [0] = &nfs40_cb_sv_ops, 251 [1] = &nfs41_cb_sv_ops, 252 }; 253 #else 254 static const struct svc_serv_ops *nfs4_cb_sv_ops[] = { 255 [0] = &nfs40_cb_sv_ops, 256 [1] = NULL, 257 }; 258 #endif 259 260 static struct svc_serv *nfs_callback_create_svc(int minorversion) 261 { 262 struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion]; 263 const struct svc_serv_ops *sv_ops; 264 struct svc_serv *serv; 265 266 /* 267 * Check whether we're already up and running. 268 */ 269 if (cb_info->serv) { 270 /* 271 * Note: increase service usage, because later in case of error 272 * svc_destroy() will be called. 273 */ 274 svc_get(cb_info->serv); 275 return cb_info->serv; 276 } 277 278 switch (minorversion) { 279 case 0: 280 sv_ops = nfs4_cb_sv_ops[0]; 281 break; 282 default: 283 sv_ops = nfs4_cb_sv_ops[1]; 284 } 285 286 if (sv_ops == NULL) 287 return ERR_PTR(-ENOTSUPP); 288 289 /* 290 * Sanity check: if there's no task, 291 * we should be the first user ... 292 */ 293 if (cb_info->users) 294 printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n", 295 cb_info->users); 296 297 serv = svc_create_pooled(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, sv_ops); 298 if (!serv) { 299 printk(KERN_ERR "nfs_callback_create_svc: create service failed\n"); 300 return ERR_PTR(-ENOMEM); 301 } 302 cb_info->serv = serv; 303 /* As there is only one thread we need to over-ride the 304 * default maximum of 80 connections 305 */ 306 serv->sv_maxconn = 1024; 307 dprintk("nfs_callback_create_svc: service created\n"); 308 return serv; 309 } 310 311 /* 312 * Bring up the callback thread if it is not already up. 313 */ 314 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt) 315 { 316 struct svc_serv *serv; 317 struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion]; 318 int ret; 319 struct net *net = xprt->xprt_net; 320 321 mutex_lock(&nfs_callback_mutex); 322 323 serv = nfs_callback_create_svc(minorversion); 324 if (IS_ERR(serv)) { 325 ret = PTR_ERR(serv); 326 goto err_create; 327 } 328 329 ret = nfs_callback_up_net(minorversion, serv, net, xprt); 330 if (ret < 0) 331 goto err_net; 332 333 ret = nfs_callback_start_svc(minorversion, xprt, serv); 334 if (ret < 0) 335 goto err_start; 336 337 cb_info->users++; 338 /* 339 * svc_create creates the svc_serv with sv_nrthreads == 1, and then 340 * svc_prepare_thread increments that. So we need to call svc_destroy 341 * on both success and failure so that the refcount is 1 when the 342 * thread exits. 343 */ 344 err_net: 345 if (!cb_info->users) 346 cb_info->serv = NULL; 347 svc_destroy(serv); 348 err_create: 349 mutex_unlock(&nfs_callback_mutex); 350 return ret; 351 352 err_start: 353 nfs_callback_down_net(minorversion, serv, net); 354 dprintk("NFS: Couldn't create server thread; err = %d\n", ret); 355 goto err_net; 356 } 357 358 /* 359 * Kill the callback thread if it's no longer being used. 360 */ 361 void nfs_callback_down(int minorversion, struct net *net) 362 { 363 struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion]; 364 struct svc_serv *serv; 365 366 mutex_lock(&nfs_callback_mutex); 367 serv = cb_info->serv; 368 nfs_callback_down_net(minorversion, serv, net); 369 cb_info->users--; 370 if (cb_info->users == 0) { 371 svc_get(serv); 372 serv->sv_ops->svo_setup(serv, NULL, 0); 373 svc_destroy(serv); 374 dprintk("nfs_callback_down: service destroyed\n"); 375 cb_info->serv = NULL; 376 } 377 mutex_unlock(&nfs_callback_mutex); 378 } 379 380 /* Boolean check of RPC_AUTH_GSS principal */ 381 int 382 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp) 383 { 384 char *p = rqstp->rq_cred.cr_principal; 385 386 if (rqstp->rq_authop->flavour != RPC_AUTH_GSS) 387 return 1; 388 389 /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */ 390 if (clp->cl_minorversion != 0) 391 return 0; 392 /* 393 * It might just be a normal user principal, in which case 394 * userspace won't bother to tell us the name at all. 395 */ 396 if (p == NULL) 397 return 0; 398 399 /* 400 * Did we get the acceptor from userland during the SETCLIENID 401 * negotiation? 402 */ 403 if (clp->cl_acceptor) 404 return !strcmp(p, clp->cl_acceptor); 405 406 /* 407 * Otherwise try to verify it using the cl_hostname. Note that this 408 * doesn't work if a non-canonical hostname was used in the devname. 409 */ 410 411 /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */ 412 413 if (memcmp(p, "nfs@", 4) != 0) 414 return 0; 415 p += 4; 416 if (strcmp(p, clp->cl_hostname) != 0) 417 return 0; 418 return 1; 419 } 420 421 /* 422 * pg_authenticate method for nfsv4 callback threads. 423 * 424 * The authflavor has been negotiated, so an incorrect flavor is a server 425 * bug. Deny packets with incorrect authflavor. 426 * 427 * All other checking done after NFS decoding where the nfs_client can be 428 * found in nfs4_callback_compound 429 */ 430 static int nfs_callback_authenticate(struct svc_rqst *rqstp) 431 { 432 switch (rqstp->rq_authop->flavour) { 433 case RPC_AUTH_NULL: 434 if (rqstp->rq_proc != CB_NULL) 435 return SVC_DENIED; 436 break; 437 case RPC_AUTH_GSS: 438 /* No RPC_AUTH_GSS support yet in NFSv4.1 */ 439 if (svc_is_backchannel(rqstp)) 440 return SVC_DENIED; 441 } 442 return SVC_OK; 443 } 444 445 /* 446 * Define NFS4 callback program 447 */ 448 static const struct svc_version *nfs4_callback_version[] = { 449 [1] = &nfs4_callback_version1, 450 [4] = &nfs4_callback_version4, 451 }; 452 453 static struct svc_stat nfs4_callback_stats; 454 455 static struct svc_program nfs4_callback_program = { 456 .pg_prog = NFS4_CALLBACK, /* RPC service number */ 457 .pg_nvers = ARRAY_SIZE(nfs4_callback_version), /* Number of entries */ 458 .pg_vers = nfs4_callback_version, /* version table */ 459 .pg_name = "NFSv4 callback", /* service name */ 460 .pg_class = "nfs", /* authentication class */ 461 .pg_stats = &nfs4_callback_stats, 462 .pg_authenticate = nfs_callback_authenticate, 463 .pg_init_request = svc_generic_init_request, 464 .pg_rpcbind_set = svc_generic_rpcbind_set, 465 }; 466