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 /*
 221  * Bring up the callback thread if it is not already up.
 222  */
 223 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 224 {
 225         struct svc_serv *serv = NULL;
 226         struct svc_rqst *rqstp;
 227         int (*callback_svc)(void *vrqstp);
 228         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 229         char svc_name[12];
 230         int ret = 0;
 231         int minorversion_setup;
 232         struct net *net = &init_net;
 233
 234         mutex_lock(&nfs_callback_mutex);
 235         if (cb_info->users++ || cb_info->task != NULL) {
 236                 nfs_callback_bc_serv(minorversion, xprt, cb_info);
 237                 goto out;
 238         }
 239         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 240         if (!serv) {
 241                 ret = -ENOMEM;
 242                 goto out_err;
 243         }
 244
 245         ret = svc_bind(serv, net);
 246         if (ret < 0) {
 247                 printk(KERN_WARNING "NFS: bind callback service failed\n");
 248                 goto out_err;
 249         }
 250
 251         minorversion_setup =  nfs_minorversion_callback_svc_setup(minorversion,
 252                                         serv, xprt, &rqstp, &callback_svc);
 253         if (!minorversion_setup) {
 254                 /* v4.0 callback setup */
 255                 rqstp = nfs4_callback_up(serv, xprt);
 256                 callback_svc = nfs4_callback_svc;
 257         }
 258
 259         if (IS_ERR(rqstp)) {
 260                 ret = PTR_ERR(rqstp);
 261                 goto out_err;
 262         }
 263
 264         svc_sock_update_bufs(serv);
 265
 266         sprintf(svc_name, "nfsv4.%u-svc", minorversion);
 267         cb_info->serv = serv;
 268         cb_info->rqst = rqstp;
 269         cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
 270         if (IS_ERR(cb_info->task)) {
 271                 ret = PTR_ERR(cb_info->task);
 272                 svc_exit_thread(cb_info->rqst);
 273                 cb_info->rqst = NULL;
 274                 cb_info->task = NULL;
 275                 goto out_err;
 276         }
 277 out:
 278         /*
 279          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 280          * svc_prepare_thread increments that. So we need to call svc_destroy
 281          * on both success and failure so that the refcount is 1 when the
 282          * thread exits.
 283          */
 284         if (serv)
 285                 svc_destroy(serv);
 286         mutex_unlock(&nfs_callback_mutex);
 287         return ret;
 288 out_err:
 289         dprintk("NFS: Couldn't create callback socket or server thread; "
 290                 "err = %d\n", ret);
 291         cb_info->users--;
 292         if (serv)
 293                 svc_shutdown_net(serv, net);
 294         goto out;
 295 }
 296
 297 /*
 298  * Kill the callback thread if it's no longer being used.
 299  */
 300 void nfs_callback_down(int minorversion)
 301 {
 302         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 303
 304         mutex_lock(&nfs_callback_mutex);
 305         cb_info->users--;
 306         if (cb_info->users == 0 && cb_info->task != NULL) {
 307                 kthread_stop(cb_info->task);
 308                 svc_shutdown_net(cb_info->serv, &init_net);
 309                 svc_exit_thread(cb_info->rqst);
 310                 cb_info->serv = NULL;
 311                 cb_info->rqst = NULL;
 312                 cb_info->task = NULL;
 313         }
 314         mutex_unlock(&nfs_callback_mutex);
 315 }
 316
 317 /* Boolean check of RPC_AUTH_GSS principal */
 318 int
 319 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
 320 {
 321         char *p = rqstp->rq_cred.cr_principal;
 322
 323         if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
 324                 return 1;
 325
 326         /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
 327         if (clp->cl_minorversion != 0)
 328                 return 0;
 329         /*
 330          * It might just be a normal user principal, in which case
 331          * userspace won't bother to tell us the name at all.
 332          */
 333         if (p == NULL)
 334                 return 0;
 335
 336         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 337
 338         if (memcmp(p, "nfs@", 4) != 0)
 339                 return 0;
 340         p += 4;
 341         if (strcmp(p, clp->cl_hostname) != 0)
 342                 return 0;
 343         return 1;
 344 }
 345
 346 /*
 347  * pg_authenticate method for nfsv4 callback threads.
 348  *
 349  * The authflavor has been negotiated, so an incorrect flavor is a server
 350  * bug. Drop packets with incorrect authflavor.
 351  *
 352  * All other checking done after NFS decoding where the nfs_client can be
 353  * found in nfs4_callback_compound
 354  */
 355 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 356 {
 357         switch (rqstp->rq_authop->flavour) {
 358         case RPC_AUTH_NULL:
 359                 if (rqstp->rq_proc != CB_NULL)
 360                         return SVC_DROP;
 361                 break;
 362         case RPC_AUTH_GSS:
 363                 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
 364                  if (svc_is_backchannel(rqstp))
 365                         return SVC_DROP;
 366         }
 367         return SVC_OK;
 368 }
 369
 370 /*
 371  * Define NFS4 callback program
 372  */
 373 static struct svc_version *nfs4_callback_version[] = {
 374         [1] = &nfs4_callback_version1,
 375         [4] = &nfs4_callback_version4,
 376 };
 377
 378 static struct svc_stat nfs4_callback_stats;
 379
 380 static struct svc_program nfs4_callback_program = {
 381         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 382         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 383         .pg_vers = nfs4_callback_version,               /* version table */
 384         .pg_name = "NFSv4 callback",                    /* service name */
 385         .pg_class = "nfs",                              /* authentication class */
 386         .pg_stats = &nfs4_callback_stats,
 387         .pg_authenticate = nfs_callback_authenticate,
 388 };