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