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/sunrpc/svc.h>
  13 #include <linux/sunrpc/svcsock.h>
  14 #include <linux/nfs_fs.h>
  15 #include <linux/mutex.h>
  16 #include <linux/freezer.h>
  17 #include <linux/kthread.h>
  18 #include <linux/sunrpc/svcauth_gss.h>
  19 #include <linux/sunrpc/bc_xprt.h>
  20
  21 #include <net/inet_sock.h>
  22
  23 #include "nfs4_fs.h"
  24 #include "callback.h"
  25 #include "internal.h"
  26
  27 #define NFSDBG_FACILITY NFSDBG_CALLBACK
  28
  29 struct nfs_callback_data {
  30         unsigned int users;
  31         struct svc_serv *serv;
  32         struct svc_rqst *rqst;
  33         struct task_struct *task;
  34 };
  35
  36 static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
  37 static DEFINE_MUTEX(nfs_callback_mutex);
  38 static struct svc_program nfs4_callback_program;
  39
  40 unsigned short nfs_callback_tcpport6;
  41
  42 /*
  43  * This is the NFSv4 callback kernel thread.
  44  */
  45 static int
  46 nfs4_callback_svc(void *vrqstp)
  47 {
  48         int err, preverr = 0;
  49         struct svc_rqst *rqstp = vrqstp;
  50
  51         set_freezable();
  52
  53         while (!kthread_should_stop()) {
  54                 /*
  55                  * Listen for a request on the socket
  56                  */
  57                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  58                 if (err == -EAGAIN || err == -EINTR) {
  59                         preverr = err;
  60                         continue;
  61                 }
  62                 if (err < 0) {
  63                         if (err != preverr) {
  64                                 printk(KERN_WARNING "NFS: %s: unexpected error "
  65                                         "from svc_recv (%d)\n", __func__, err);
  66                                 preverr = err;
  67                         }
  68                         schedule_timeout_uninterruptible(HZ);
  69                         continue;
  70                 }
  71                 preverr = err;
  72                 svc_process(rqstp);
  73         }
  74         return 0;
  75 }
  76
  77 /*
  78  * Prepare to bring up the NFSv4 callback service
  79  */
  80 static struct svc_rqst *
  81 nfs4_callback_up(struct svc_serv *serv, struct rpc_xprt *xprt)
  82 {
  83         int ret;
  84
  85         ret = svc_create_xprt(serv, "tcp", &init_net, PF_INET,
  86                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
  87         if (ret <= 0)
  88                 goto out_err;
  89         nfs_callback_tcpport = ret;
  90         dprintk("NFS: Callback listener port = %u (af %u)\n",
  91                         nfs_callback_tcpport, PF_INET);
  92
  93         ret = svc_create_xprt(serv, "tcp", &init_net, PF_INET6,
  94                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
  95         if (ret > 0) {
  96                 nfs_callback_tcpport6 = ret;
  97                 dprintk("NFS: Callback listener port = %u (af %u)\n",
  98                                 nfs_callback_tcpport6, PF_INET6);
  99         } else if (ret == -EAFNOSUPPORT)
 100                 ret = 0;
 101         else
 102                 goto out_err;
 103
 104         return svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);
 105
 106 out_err:
 107         if (ret == 0)
 108                 ret = -ENOMEM;
 109         return ERR_PTR(ret);
 110 }
 111
 112 #if defined(CONFIG_NFS_V4_1)
 113 /*
 114  * The callback service for NFSv4.1 callbacks
 115  */
 116 static int
 117 nfs41_callback_svc(void *vrqstp)
 118 {
 119         struct svc_rqst *rqstp = vrqstp;
 120         struct svc_serv *serv = rqstp->rq_server;
 121         struct rpc_rqst *req;
 122         int error;
 123         DEFINE_WAIT(wq);
 124
 125         set_freezable();
 126
 127         while (!kthread_should_stop()) {
 128                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
 129                 spin_lock_bh(&serv->sv_cb_lock);
 130                 if (!list_empty(&serv->sv_cb_list)) {
 131                         req = list_first_entry(&serv->sv_cb_list,
 132                                         struct rpc_rqst, rq_bc_list);
 133                         list_del(&req->rq_bc_list);
 134                         spin_unlock_bh(&serv->sv_cb_lock);
 135                         dprintk("Invoking bc_svc_process()\n");
 136                         error = bc_svc_process(serv, req, rqstp);
 137                         dprintk("bc_svc_process() returned w/ error code= %d\n",
 138                                 error);
 139                 } else {
 140                         spin_unlock_bh(&serv->sv_cb_lock);
 141                         schedule();
 142                 }
 143                 finish_wait(&serv->sv_cb_waitq, &wq);
 144         }
 145         return 0;
 146 }
 147
 148 /*
 149  * Bring up the NFSv4.1 callback service
 150  */
 151 static struct svc_rqst *
 152 nfs41_callback_up(struct svc_serv *serv, struct rpc_xprt *xprt)
 153 {
 154         struct svc_rqst *rqstp;
 155         int ret;
 156
 157         /*
 158          * Create an svc_sock for the back channel service that shares the
 159          * fore channel connection.
 160          * Returns the input port (0) and sets the svc_serv bc_xprt on success
 161          */
 162         ret = svc_create_xprt(serv, "tcp-bc", &init_net, PF_INET, 0,
 163                               SVC_SOCK_ANONYMOUS);
 164         if (ret < 0) {
 165                 rqstp = ERR_PTR(ret);
 166                 goto out;
 167         }
 168
 169         /*
 170          * Save the svc_serv in the transport so that it can
 171          * be referenced when the session backchannel is initialized
 172          */
 173         xprt->bc_serv = serv;
 174
 175         INIT_LIST_HEAD(&serv->sv_cb_list);
 176         spin_lock_init(&serv->sv_cb_lock);
 177         init_waitqueue_head(&serv->sv_cb_waitq);
 178         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);
 179         if (IS_ERR(rqstp)) {
 180                 svc_xprt_put(serv->sv_bc_xprt);
 181                 serv->sv_bc_xprt = NULL;
 182         }
 183 out:
 184         dprintk("--> %s return %ld\n", __func__,
 185                 IS_ERR(rqstp) ? PTR_ERR(rqstp) : 0);
 186         return rqstp;
 187 }
 188
 189 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 190                 struct svc_serv *serv, struct rpc_xprt *xprt,
 191                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 192 {
 193         if (minorversion) {
 194                 *rqstpp = nfs41_callback_up(serv, xprt);
 195                 *callback_svc = nfs41_callback_svc;
 196         }
 197         return minorversion;
 198 }
 199
 200 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 201                 struct nfs_callback_data *cb_info)
 202 {
 203         if (minorversion)
 204                 xprt->bc_serv = cb_info->serv;
 205 }
 206 #else
 207 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 208                 struct svc_serv *serv, struct rpc_xprt *xprt,
 209                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 210 {
 211         return 0;
 212 }
 213
 214 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 215                 struct nfs_callback_data *cb_info)
 216 {
 217 }
 218 #endif /* CONFIG_NFS_V4_1 */
 219
 220 static struct svc_serv *nfs_callback_create_svc(int minorversion)
 221 {
 222         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 223         struct svc_serv *serv;
 224
 225         /*
 226          * Check whether we're already up and running.
 227          */
 228         if (cb_info->task) {
 229                 /*
 230                  * Note: increase service usage, because later in case of error
 231                  * svc_destroy() will be called.
 232                  */
 233                 svc_get(cb_info->serv);
 234                 return cb_info->serv;
 235         }
 236
 237         /*
 238          * Sanity check: if there's no task,
 239          * we should be the first user ...
 240          */
 241         if (cb_info->users)
 242                 printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
 243                         cb_info->users);
 244
 245         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 246         if (!serv) {
 247                 printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
 248                 return ERR_PTR(-ENOMEM);
 249         }
 250         /* As there is only one thread we need to over-ride the
 251          * default maximum of 80 connections
 252          */
 253         serv->sv_maxconn = 1024;
 254         dprintk("nfs_callback_create_svc: service created\n");
 255         return serv;
 256 }
 257
 258 /*
 259  * Bring up the callback thread if it is not already up.
 260  */
 261 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 262 {
 263         struct svc_serv *serv;
 264         struct svc_rqst *rqstp;
 265         int (*callback_svc)(void *vrqstp);
 266         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 267         char svc_name[12];
 268         int ret = 0;
 269         int minorversion_setup;
 270         struct net *net = &init_net;
 271
 272         mutex_lock(&nfs_callback_mutex);
 273
 274         serv = nfs_callback_create_svc(minorversion);
 275         if (IS_ERR(serv)) {
 276                 ret = PTR_ERR(serv);
 277                 goto err_create;
 278         }
 279
 280         if (cb_info->users++ || cb_info->task != NULL) {
 281                 nfs_callback_bc_serv(minorversion, xprt, cb_info);
 282                 goto out;
 283         }
 284
 285         ret = svc_bind(serv, net);
 286         if (ret < 0) {
 287                 printk(KERN_WARNING "NFS: bind callback service failed\n");
 288                 goto out_err;
 289         }
 290
 291         minorversion_setup =  nfs_minorversion_callback_svc_setup(minorversion,
 292                                         serv, xprt, &rqstp, &callback_svc);
 293         if (!minorversion_setup) {
 294                 /* v4.0 callback setup */
 295                 rqstp = nfs4_callback_up(serv, xprt);
 296                 callback_svc = nfs4_callback_svc;
 297         }
 298
 299         if (IS_ERR(rqstp)) {
 300                 ret = PTR_ERR(rqstp);
 301                 goto out_err;
 302         }
 303
 304         svc_sock_update_bufs(serv);
 305
 306         sprintf(svc_name, "nfsv4.%u-svc", minorversion);
 307         cb_info->serv = serv;
 308         cb_info->rqst = rqstp;
 309         cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
 310         if (IS_ERR(cb_info->task)) {
 311                 ret = PTR_ERR(cb_info->task);
 312                 svc_exit_thread(cb_info->rqst);
 313                 cb_info->rqst = NULL;
 314                 cb_info->task = NULL;
 315                 goto out_err;
 316         }
 317 out:
 318         /*
 319          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 320          * svc_prepare_thread increments that. So we need to call svc_destroy
 321          * on both success and failure so that the refcount is 1 when the
 322          * thread exits.
 323          */
 324         svc_destroy(serv);
 325 err_create:
 326         mutex_unlock(&nfs_callback_mutex);
 327         return ret;
 328 out_err:
 329         dprintk("NFS: Couldn't create callback socket or server thread; "
 330                 "err = %d\n", ret);
 331         cb_info->users--;
 332         svc_shutdown_net(serv, net);
 333         goto out;
 334 }
 335
 336 /*
 337  * Kill the callback thread if it's no longer being used.
 338  */
 339 void nfs_callback_down(int minorversion, struct net *net)
 340 {
 341         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 342
 343         mutex_lock(&nfs_callback_mutex);
 344         cb_info->users--;
 345         if (cb_info->users == 0 && cb_info->task != NULL) {
 346                 kthread_stop(cb_info->task);
 347                 svc_shutdown_net(cb_info->serv, net);
 348                 svc_exit_thread(cb_info->rqst);
 349                 cb_info->serv = NULL;
 350                 cb_info->rqst = NULL;
 351                 cb_info->task = NULL;
 352         }
 353         mutex_unlock(&nfs_callback_mutex);
 354 }
 355
 356 /* Boolean check of RPC_AUTH_GSS principal */
 357 int
 358 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
 359 {
 360         char *p = rqstp->rq_cred.cr_principal;
 361
 362         if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
 363                 return 1;
 364
 365         /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
 366         if (clp->cl_minorversion != 0)
 367                 return 0;
 368         /*
 369          * It might just be a normal user principal, in which case
 370          * userspace won't bother to tell us the name at all.
 371          */
 372         if (p == NULL)
 373                 return 0;
 374
 375         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 376
 377         if (memcmp(p, "nfs@", 4) != 0)
 378                 return 0;
 379         p += 4;
 380         if (strcmp(p, clp->cl_hostname) != 0)
 381                 return 0;
 382         return 1;
 383 }
 384
 385 /*
 386  * pg_authenticate method for nfsv4 callback threads.
 387  *
 388  * The authflavor has been negotiated, so an incorrect flavor is a server
 389  * bug. Drop packets with incorrect authflavor.
 390  *
 391  * All other checking done after NFS decoding where the nfs_client can be
 392  * found in nfs4_callback_compound
 393  */
 394 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 395 {
 396         switch (rqstp->rq_authop->flavour) {
 397         case RPC_AUTH_NULL:
 398                 if (rqstp->rq_proc != CB_NULL)
 399                         return SVC_DROP;
 400                 break;
 401         case RPC_AUTH_GSS:
 402                 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
 403                  if (svc_is_backchannel(rqstp))
 404                         return SVC_DROP;
 405         }
 406         return SVC_OK;
 407 }
 408
 409 /*
 410  * Define NFS4 callback program
 411  */
 412 static struct svc_version *nfs4_callback_version[] = {
 413         [1] = &nfs4_callback_version1,
 414         [4] = &nfs4_callback_version4,
 415 };
 416
 417 static struct svc_stat nfs4_callback_stats;
 418
 419 static struct svc_program nfs4_callback_program = {
 420         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 421         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 422         .pg_vers = nfs4_callback_version,               /* version table */
 423         .pg_name = "NFSv4 callback",                    /* service name */
 424         .pg_class = "nfs",                              /* authentication class */
 425         .pg_stats = &nfs4_callback_stats,
 426         .pg_authenticate = nfs_callback_authenticate,
 427 };