fs/nfs/callback.c

   1 /*
   2  * linux/fs/nfs/callback.c
   3  *
   4  * Copyright (C) 2004 Trond Myklebust
   5  *
   6  * NFSv4 callback handling
   7  */
   8
   9 #include <linux/completion.h>
  10 #include <linux/ip.h>
  11 #include <linux/module.h>
  12 #include <linux/sched/signal.h>
  13 #include <linux/sunrpc/svc.h>
  14 #include <linux/sunrpc/svcsock.h>
  15 #include <linux/nfs_fs.h>
  16 #include <linux/errno.h>
  17 #include <linux/mutex.h>
  18 #include <linux/freezer.h>
  19 #include <linux/kthread.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
  41 static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
  42 {
  43         int ret;
  44         struct nfs_net *nn = net_generic(net, nfs_net_id);
  45
  46         ret = svc_create_xprt(serv, "tcp", net, PF_INET,
  47                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
  48         if (ret <= 0)
  49                 goto out_err;
  50         nn->nfs_callback_tcpport = ret;
  51         dprintk("NFS: Callback listener port = %u (af %u, net %p)\n",
  52                         nn->nfs_callback_tcpport, PF_INET, net);
  53
  54         ret = svc_create_xprt(serv, "tcp", net, PF_INET6,
  55                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
  56         if (ret > 0) {
  57                 nn->nfs_callback_tcpport6 = ret;
  58                 dprintk("NFS: Callback listener port = %u (af %u, net %p)\n",
  59                                 nn->nfs_callback_tcpport6, PF_INET6, net);
  60         } else if (ret != -EAFNOSUPPORT)
  61                 goto out_err;
  62         return 0;
  63
  64 out_err:
  65         return (ret) ? ret : -ENOMEM;
  66 }
  67
  68 /*
  69  * This is the NFSv4 callback kernel thread.
  70  */
  71 static int
  72 nfs4_callback_svc(void *vrqstp)
  73 {
  74         int err;
  75         struct svc_rqst *rqstp = vrqstp;
  76
  77         set_freezable();
  78
  79         while (!kthread_freezable_should_stop(NULL)) {
  80
  81                 if (signal_pending(current))
  82                         flush_signals(current);
  83                 /*
  84                  * Listen for a request on the socket
  85                  */
  86                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  87                 if (err == -EAGAIN || err == -EINTR)
  88                         continue;
  89                 svc_process(rqstp);
  90         }
  91         svc_exit_thread(rqstp);
  92         module_put_and_exit(0);
  93         return 0;
  94 }
  95
  96 #if defined(CONFIG_NFS_V4_1)
  97 /*
  98  * The callback service for NFSv4.1 callbacks
  99  */
 100 static int
 101 nfs41_callback_svc(void *vrqstp)
 102 {
 103         struct svc_rqst *rqstp = vrqstp;
 104         struct svc_serv *serv = rqstp->rq_server;
 105         struct rpc_rqst *req;
 106         int error;
 107         DEFINE_WAIT(wq);
 108
 109         set_freezable();
 110
 111         while (!kthread_freezable_should_stop(NULL)) {
 112
 113                 if (signal_pending(current))
 114                         flush_signals(current);
 115
 116                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
 117                 spin_lock_bh(&serv->sv_cb_lock);
 118                 if (!list_empty(&serv->sv_cb_list)) {
 119                         req = list_first_entry(&serv->sv_cb_list,
 120                                         struct rpc_rqst, rq_bc_list);
 121                         list_del(&req->rq_bc_list);
 122                         spin_unlock_bh(&serv->sv_cb_lock);
 123                         finish_wait(&serv->sv_cb_waitq, &wq);
 124                         dprintk("Invoking bc_svc_process()\n");
 125                         error = bc_svc_process(serv, req, rqstp);
 126                         dprintk("bc_svc_process() returned w/ error code= %d\n",
 127                                 error);
 128                 } else {
 129                         spin_unlock_bh(&serv->sv_cb_lock);
 130                         if (!kthread_should_stop())
 131                                 schedule();
 132                         finish_wait(&serv->sv_cb_waitq, &wq);
 133                 }
 134         }
 135         svc_exit_thread(rqstp);
 136         module_put_and_exit(0);
 137         return 0;
 138 }
 139
 140 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 141                 struct svc_serv *serv)
 142 {
 143         if (minorversion)
 144                 /*
 145                  * Save the svc_serv in the transport so that it can
 146                  * be referenced when the session backchannel is initialized
 147                  */
 148                 xprt->bc_serv = serv;
 149 }
 150 #else
 151 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 152                 struct svc_serv *serv)
 153 {
 154 }
 155 #endif /* CONFIG_NFS_V4_1 */
 156
 157 static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
 158                                   struct svc_serv *serv)
 159 {
 160         int nrservs = nfs_callback_nr_threads;
 161         int ret;
 162
 163         nfs_callback_bc_serv(minorversion, xprt, serv);
 164
 165         if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
 166                 nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
 167
 168         if (serv->sv_nrthreads-1 == nrservs)
 169                 return 0;
 170
 171         ret = serv->sv_ops->svo_setup(serv, NULL, nrservs);
 172         if (ret) {
 173                 serv->sv_ops->svo_setup(serv, NULL, 0);
 174                 return ret;
 175         }
 176         dprintk("nfs_callback_up: service started\n");
 177         return 0;
 178 }
 179
 180 static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
 181 {
 182         struct nfs_net *nn = net_generic(net, nfs_net_id);
 183
 184         if (--nn->cb_users[minorversion])
 185                 return;
 186
 187         dprintk("NFS: destroy per-net callback data; net=%p\n", net);
 188         svc_shutdown_net(serv, net);
 189 }
 190
 191 static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
 192                                struct net *net, struct rpc_xprt *xprt)
 193 {
 194         struct nfs_net *nn = net_generic(net, nfs_net_id);
 195         int ret;
 196
 197         if (nn->cb_users[minorversion]++)
 198                 return 0;
 199
 200         dprintk("NFS: create per-net callback data; net=%p\n", net);
 201
 202         ret = svc_bind(serv, net);
 203         if (ret < 0) {
 204                 printk(KERN_WARNING "NFS: bind callback service failed\n");
 205                 goto err_bind;
 206         }
 207
 208         ret = -EPROTONOSUPPORT;
 209         if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
 210                 ret = nfs4_callback_up_net(serv, net);
 211         else if (xprt->ops->bc_up)
 212                 ret = xprt->ops->bc_up(serv, net);
 213
 214         if (ret < 0) {
 215                 printk(KERN_ERR "NFS: callback service start failed\n");
 216                 goto err_socks;
 217         }
 218         return 0;
 219
 220 err_socks:
 221         svc_rpcb_cleanup(serv, net);
 222 err_bind:
 223         nn->cb_users[minorversion]--;
 224         dprintk("NFS: Couldn't create callback socket: err = %d; "
 225                         "net = %p\n", ret, net);
 226         return ret;
 227 }
 228
 229 static struct svc_serv_ops nfs40_cb_sv_ops = {
 230         .svo_function           = nfs4_callback_svc,
 231         .svo_enqueue_xprt       = svc_xprt_do_enqueue,
 232         .svo_setup              = svc_set_num_threads_sync,
 233         .svo_module             = THIS_MODULE,
 234 };
 235 #if defined(CONFIG_NFS_V4_1)
 236 static struct svc_serv_ops nfs41_cb_sv_ops = {
 237         .svo_function           = nfs41_callback_svc,
 238         .svo_enqueue_xprt       = svc_xprt_do_enqueue,
 239         .svo_setup              = svc_set_num_threads_sync,
 240         .svo_module             = THIS_MODULE,
 241 };
 242
 243 static struct svc_serv_ops *nfs4_cb_sv_ops[] = {
 244         [0] = &nfs40_cb_sv_ops,
 245         [1] = &nfs41_cb_sv_ops,
 246 };
 247 #else
 248 static struct svc_serv_ops *nfs4_cb_sv_ops[] = {
 249         [0] = &nfs40_cb_sv_ops,
 250         [1] = NULL,
 251 };
 252 #endif
 253
 254 static struct svc_serv *nfs_callback_create_svc(int minorversion)
 255 {
 256         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 257         struct svc_serv *serv;
 258         struct svc_serv_ops *sv_ops;
 259
 260         /*
 261          * Check whether we're already up and running.
 262          */
 263         if (cb_info->serv) {
 264                 /*
 265                  * Note: increase service usage, because later in case of error
 266                  * svc_destroy() will be called.
 267                  */
 268                 svc_get(cb_info->serv);
 269                 return cb_info->serv;
 270         }
 271
 272         switch (minorversion) {
 273         case 0:
 274                 sv_ops = nfs4_cb_sv_ops[0];
 275                 break;
 276         default:
 277                 sv_ops = nfs4_cb_sv_ops[1];
 278         }
 279
 280         if (sv_ops == NULL)
 281                 return ERR_PTR(-ENOTSUPP);
 282
 283         /*
 284          * Sanity check: if there's no task,
 285          * we should be the first user ...
 286          */
 287         if (cb_info->users)
 288                 printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
 289                         cb_info->users);
 290
 291         serv = svc_create_pooled(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, sv_ops);
 292         if (!serv) {
 293                 printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
 294                 return ERR_PTR(-ENOMEM);
 295         }
 296         cb_info->serv = serv;
 297         /* As there is only one thread we need to over-ride the
 298          * default maximum of 80 connections
 299          */
 300         serv->sv_maxconn = 1024;
 301         dprintk("nfs_callback_create_svc: service created\n");
 302         return serv;
 303 }
 304
 305 /*
 306  * Bring up the callback thread if it is not already up.
 307  */
 308 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 309 {
 310         struct svc_serv *serv;
 311         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 312         int ret;
 313         struct net *net = xprt->xprt_net;
 314
 315         mutex_lock(&nfs_callback_mutex);
 316
 317         serv = nfs_callback_create_svc(minorversion);
 318         if (IS_ERR(serv)) {
 319                 ret = PTR_ERR(serv);
 320                 goto err_create;
 321         }
 322
 323         ret = nfs_callback_up_net(minorversion, serv, net, xprt);
 324         if (ret < 0)
 325                 goto err_net;
 326
 327         ret = nfs_callback_start_svc(minorversion, xprt, serv);
 328         if (ret < 0)
 329                 goto err_start;
 330
 331         cb_info->users++;
 332         /*
 333          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 334          * svc_prepare_thread increments that. So we need to call svc_destroy
 335          * on both success and failure so that the refcount is 1 when the
 336          * thread exits.
 337          */
 338 err_net:
 339         if (!cb_info->users)
 340                 cb_info->serv = NULL;
 341         svc_destroy(serv);
 342 err_create:
 343         mutex_unlock(&nfs_callback_mutex);
 344         return ret;
 345
 346 err_start:
 347         nfs_callback_down_net(minorversion, serv, net);
 348         dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
 349         goto err_net;
 350 }
 351
 352 /*
 353  * Kill the callback thread if it's no longer being used.
 354  */
 355 void nfs_callback_down(int minorversion, struct net *net)
 356 {
 357         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 358         struct svc_serv *serv;
 359
 360         mutex_lock(&nfs_callback_mutex);
 361         serv = cb_info->serv;
 362         nfs_callback_down_net(minorversion, serv, net);
 363         cb_info->users--;
 364         if (cb_info->users == 0) {
 365                 svc_get(serv);
 366                 serv->sv_ops->svo_setup(serv, NULL, 0);
 367                 svc_destroy(serv);
 368                 dprintk("nfs_callback_down: service destroyed\n");
 369                 cb_info->serv = NULL;
 370         }
 371         mutex_unlock(&nfs_callback_mutex);
 372 }
 373
 374 /* Boolean check of RPC_AUTH_GSS principal */
 375 int
 376 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
 377 {
 378         char *p = rqstp->rq_cred.cr_principal;
 379
 380         if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
 381                 return 1;
 382
 383         /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
 384         if (clp->cl_minorversion != 0)
 385                 return 0;
 386         /*
 387          * It might just be a normal user principal, in which case
 388          * userspace won't bother to tell us the name at all.
 389          */
 390         if (p == NULL)
 391                 return 0;
 392
 393         /*
 394          * Did we get the acceptor from userland during the SETCLIENID
 395          * negotiation?
 396          */
 397         if (clp->cl_acceptor)
 398                 return !strcmp(p, clp->cl_acceptor);
 399
 400         /*
 401          * Otherwise try to verify it using the cl_hostname. Note that this
 402          * doesn't work if a non-canonical hostname was used in the devname.
 403          */
 404
 405         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 406
 407         if (memcmp(p, "nfs@", 4) != 0)
 408                 return 0;
 409         p += 4;
 410         if (strcmp(p, clp->cl_hostname) != 0)
 411                 return 0;
 412         return 1;
 413 }
 414
 415 /*
 416  * pg_authenticate method for nfsv4 callback threads.
 417  *
 418  * The authflavor has been negotiated, so an incorrect flavor is a server
 419  * bug. Deny packets with incorrect authflavor.
 420  *
 421  * All other checking done after NFS decoding where the nfs_client can be
 422  * found in nfs4_callback_compound
 423  */
 424 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 425 {
 426         switch (rqstp->rq_authop->flavour) {
 427         case RPC_AUTH_NULL:
 428                 if (rqstp->rq_proc != CB_NULL)
 429                         return SVC_DENIED;
 430                 break;
 431         case RPC_AUTH_GSS:
 432                 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
 433                  if (svc_is_backchannel(rqstp))
 434                         return SVC_DENIED;
 435         }
 436         return SVC_OK;
 437 }
 438
 439 /*
 440  * Define NFS4 callback program
 441  */
 442 static const struct svc_version *nfs4_callback_version[] = {
 443         [1] = &nfs4_callback_version1,
 444         [4] = &nfs4_callback_version4,
 445 };
 446
 447 static struct svc_stat nfs4_callback_stats;
 448
 449 static struct svc_program nfs4_callback_program = {
 450         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 451         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 452         .pg_vers = nfs4_callback_version,               /* version table */
 453         .pg_name = "NFSv4 callback",                    /* service name */
 454         .pg_class = "nfs",                              /* authentication class */
 455         .pg_stats = &nfs4_callback_stats,
 456         .pg_authenticate = nfs_callback_authenticate,
 457 };