fs/nfs/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/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 };