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