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/smp_lock.h>
  13 #include <linux/sunrpc/svc.h>
  14 #include <linux/sunrpc/svcsock.h>
  15 #include <linux/nfs_fs.h>
  16 #include <linux/mutex.h>
  17 #include <linux/freezer.h>
  18 #include <linux/kthread.h>
  19 #include <linux/sunrpc/svcauth_gss.h>
  20 #if defined(CONFIG_NFS_V4_1)
  21 #include <linux/sunrpc/bc_xprt.h>
  22 #endif
  23
  24 #include <net/inet_sock.h>
  25
  26 #include "nfs4_fs.h"
  27 #include "callback.h"
  28 #include "internal.h"
  29
  30 #define NFSDBG_FACILITY NFSDBG_CALLBACK
  31
  32 struct nfs_callback_data {
  33         unsigned int users;
  34         struct svc_serv *serv;
  35         struct svc_rqst *rqst;
  36         struct task_struct *task;
  37 };
  38
  39 static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
  40 static DEFINE_MUTEX(nfs_callback_mutex);
  41 static struct svc_program nfs4_callback_program;
  42
  43 unsigned int nfs_callback_set_tcpport;
  44 unsigned short nfs_callback_tcpport;
  45 unsigned short nfs_callback_tcpport6;
  46 #define NFS_CALLBACK_MAXPORTNR (65535U)
  47
  48 static int param_set_portnr(const char *val, struct kernel_param *kp)
  49 {
  50         unsigned long num;
  51         int ret;
  52
  53         if (!val)
  54                 return -EINVAL;
  55         ret = strict_strtoul(val, 0, &num);
  56         if (ret == -EINVAL || num > NFS_CALLBACK_MAXPORTNR)
  57                 return -EINVAL;
  58         *((unsigned int *)kp->arg) = num;
  59         return 0;
  60 }
  61
  62 static int param_get_portnr(char *buffer, struct kernel_param *kp)
  63 {
  64         return param_get_uint(buffer, kp);
  65 }
  66 #define param_check_portnr(name, p) __param_check(name, p, unsigned int);
  67
  68 module_param_named(callback_tcpport, nfs_callback_set_tcpport, portnr, 0644);
  69
  70 /*
  71  * This is the NFSv4 callback kernel thread.
  72  */
  73 static int
  74 nfs4_callback_svc(void *vrqstp)
  75 {
  76         int err, preverr = 0;
  77         struct svc_rqst *rqstp = vrqstp;
  78
  79         set_freezable();
  80
  81         /*
  82          * FIXME: do we really need to run this under the BKL? If so, please
  83          * add a comment about what it's intended to protect.
  84          */
  85         lock_kernel();
  86         while (!kthread_should_stop()) {
  87                 /*
  88                  * Listen for a request on the socket
  89                  */
  90                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  91                 if (err == -EAGAIN || err == -EINTR) {
  92                         preverr = err;
  93                         continue;
  94                 }
  95                 if (err < 0) {
  96                         if (err != preverr) {
  97                                 printk(KERN_WARNING "%s: unexpected error "
  98                                         "from svc_recv (%d)\n", __func__, err);
  99                                 preverr = err;
 100                         }
 101                         schedule_timeout_uninterruptible(HZ);
 102                         continue;
 103                 }
 104                 preverr = err;
 105                 svc_process(rqstp);
 106         }
 107         unlock_kernel();
 108         return 0;
 109 }
 110
 111 /*
 112  * Prepare to bring up the NFSv4 callback service
 113  */
 114 struct svc_rqst *
 115 nfs4_callback_up(struct svc_serv *serv)
 116 {
 117         int ret;
 118
 119         ret = svc_create_xprt(serv, "tcp", PF_INET,
 120                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 121         if (ret <= 0)
 122                 goto out_err;
 123         nfs_callback_tcpport = ret;
 124         dprintk("NFS: Callback listener port = %u (af %u)\n",
 125                         nfs_callback_tcpport, PF_INET);
 126
 127 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 128         ret = svc_create_xprt(serv, "tcp", PF_INET6,
 129                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 130         if (ret > 0) {
 131                 nfs_callback_tcpport6 = ret;
 132                 dprintk("NFS: Callback listener port = %u (af %u)\n",
 133                                 nfs_callback_tcpport6, PF_INET6);
 134         } else if (ret == -EAFNOSUPPORT)
 135                 ret = 0;
 136         else
 137                 goto out_err;
 138 #endif  /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
 139
 140         return svc_prepare_thread(serv, &serv->sv_pools[0]);
 141
 142 out_err:
 143         if (ret == 0)
 144                 ret = -ENOMEM;
 145         return ERR_PTR(ret);
 146 }
 147
 148 #if defined(CONFIG_NFS_V4_1)
 149 /*
 150  * The callback service for NFSv4.1 callbacks
 151  */
 152 static int
 153 nfs41_callback_svc(void *vrqstp)
 154 {
 155         struct svc_rqst *rqstp = vrqstp;
 156         struct svc_serv *serv = rqstp->rq_server;
 157         struct rpc_rqst *req;
 158         int error;
 159         DEFINE_WAIT(wq);
 160
 161         set_freezable();
 162
 163         /*
 164          * FIXME: do we really need to run this under the BKL? If so, please
 165          * add a comment about what it's intended to protect.
 166          */
 167         lock_kernel();
 168         while (!kthread_should_stop()) {
 169                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
 170                 spin_lock_bh(&serv->sv_cb_lock);
 171                 if (!list_empty(&serv->sv_cb_list)) {
 172                         req = list_first_entry(&serv->sv_cb_list,
 173                                         struct rpc_rqst, rq_bc_list);
 174                         list_del(&req->rq_bc_list);
 175                         spin_unlock_bh(&serv->sv_cb_lock);
 176                         dprintk("Invoking bc_svc_process()\n");
 177                         error = bc_svc_process(serv, req, rqstp);
 178                         dprintk("bc_svc_process() returned w/ error code= %d\n",
 179                                 error);
 180                 } else {
 181                         spin_unlock_bh(&serv->sv_cb_lock);
 182                         schedule();
 183                 }
 184                 finish_wait(&serv->sv_cb_waitq, &wq);
 185         }
 186         unlock_kernel();
 187         return 0;
 188 }
 189
 190 /*
 191  * Bring up the NFSv4.1 callback service
 192  */
 193 struct svc_rqst *
 194 nfs41_callback_up(struct svc_serv *serv, struct rpc_xprt *xprt)
 195 {
 196         struct svc_xprt *bc_xprt;
 197         struct svc_rqst *rqstp = ERR_PTR(-ENOMEM);
 198
 199         dprintk("--> %s\n", __func__);
 200         /* Create a svc_sock for the service */
 201         bc_xprt = svc_sock_create(serv, xprt->prot);
 202         if (!bc_xprt)
 203                 goto out;
 204
 205         /*
 206          * Save the svc_serv in the transport so that it can
 207          * be referenced when the session backchannel is initialized
 208          */
 209         serv->bc_xprt = bc_xprt;
 210         xprt->bc_serv = serv;
 211
 212         INIT_LIST_HEAD(&serv->sv_cb_list);
 213         spin_lock_init(&serv->sv_cb_lock);
 214         init_waitqueue_head(&serv->sv_cb_waitq);
 215         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
 216         if (IS_ERR(rqstp))
 217                 svc_sock_destroy(bc_xprt);
 218 out:
 219         dprintk("--> %s return %p\n", __func__, rqstp);
 220         return rqstp;
 221 }
 222
 223 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 224                 struct svc_serv *serv, struct rpc_xprt *xprt,
 225                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 226 {
 227         if (minorversion) {
 228                 *rqstpp = nfs41_callback_up(serv, xprt);
 229                 *callback_svc = nfs41_callback_svc;
 230         }
 231         return minorversion;
 232 }
 233
 234 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 235                 struct nfs_callback_data *cb_info)
 236 {
 237         if (minorversion)
 238                 xprt->bc_serv = cb_info->serv;
 239 }
 240 #else
 241 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 242                 struct svc_serv *serv, struct rpc_xprt *xprt,
 243                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 244 {
 245         return 0;
 246 }
 247
 248 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 249                 struct nfs_callback_data *cb_info)
 250 {
 251 }
 252 #endif /* CONFIG_NFS_V4_1 */
 253
 254 /*
 255  * Bring up the callback thread if it is not already up.
 256  */
 257 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 258 {
 259         struct svc_serv *serv = NULL;
 260         struct svc_rqst *rqstp;
 261         int (*callback_svc)(void *vrqstp);
 262         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 263         char svc_name[12];
 264         int ret = 0;
 265         int minorversion_setup;
 266
 267         mutex_lock(&nfs_callback_mutex);
 268         if (cb_info->users++ || cb_info->task != NULL) {
 269                 nfs_callback_bc_serv(minorversion, xprt, cb_info);
 270                 goto out;
 271         }
 272         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 273         if (!serv) {
 274                 ret = -ENOMEM;
 275                 goto out_err;
 276         }
 277
 278         minorversion_setup =  nfs_minorversion_callback_svc_setup(minorversion,
 279                                         serv, xprt, &rqstp, &callback_svc);
 280         if (!minorversion_setup) {
 281                 /* v4.0 callback setup */
 282                 rqstp = nfs4_callback_up(serv);
 283                 callback_svc = nfs4_callback_svc;
 284         }
 285
 286         if (IS_ERR(rqstp)) {
 287                 ret = PTR_ERR(rqstp);
 288                 goto out_err;
 289         }
 290
 291         svc_sock_update_bufs(serv);
 292
 293         sprintf(svc_name, "nfsv4.%u-svc", minorversion);
 294         cb_info->serv = serv;
 295         cb_info->rqst = rqstp;
 296         cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
 297         if (IS_ERR(cb_info->task)) {
 298                 ret = PTR_ERR(cb_info->task);
 299                 svc_exit_thread(cb_info->rqst);
 300                 cb_info->rqst = NULL;
 301                 cb_info->task = NULL;
 302                 goto out_err;
 303         }
 304 out:
 305         /*
 306          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 307          * svc_prepare_thread increments that. So we need to call svc_destroy
 308          * on both success and failure so that the refcount is 1 when the
 309          * thread exits.
 310          */
 311         if (serv)
 312                 svc_destroy(serv);
 313         mutex_unlock(&nfs_callback_mutex);
 314         return ret;
 315 out_err:
 316         dprintk("NFS: Couldn't create callback socket or server thread; "
 317                 "err = %d\n", ret);
 318         cb_info->users--;
 319         goto out;
 320 }
 321
 322 /*
 323  * Kill the callback thread if it's no longer being used.
 324  */
 325 void nfs_callback_down(int minorversion)
 326 {
 327         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 328
 329         mutex_lock(&nfs_callback_mutex);
 330         cb_info->users--;
 331         if (cb_info->users == 0 && cb_info->task != NULL) {
 332                 kthread_stop(cb_info->task);
 333                 svc_exit_thread(cb_info->rqst);
 334                 cb_info->serv = NULL;
 335                 cb_info->rqst = NULL;
 336                 cb_info->task = NULL;
 337         }
 338         mutex_unlock(&nfs_callback_mutex);
 339 }
 340
 341 static int check_gss_callback_principal(struct nfs_client *clp,
 342                                         struct svc_rqst *rqstp)
 343 {
 344         struct rpc_clnt *r = clp->cl_rpcclient;
 345         char *p = svc_gss_principal(rqstp);
 346
 347         /*
 348          * It might just be a normal user principal, in which case
 349          * userspace won't bother to tell us the name at all.
 350          */
 351         if (p == NULL)
 352                 return SVC_DENIED;
 353
 354         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 355
 356         if (memcmp(p, "nfs@", 4) != 0)
 357                 return SVC_DENIED;
 358         p += 4;
 359         if (strcmp(p, r->cl_server) != 0)
 360                 return SVC_DENIED;
 361         return SVC_OK;
 362 }
 363
 364 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 365 {
 366         struct nfs_client *clp;
 367         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 368         int ret = SVC_OK;
 369
 370         /* Don't talk to strangers */
 371         clp = nfs_find_client(svc_addr(rqstp), 4);
 372         if (clp == NULL)
 373                 return SVC_DROP;
 374
 375         dprintk("%s: %s NFSv4 callback!\n", __func__,
 376                         svc_print_addr(rqstp, buf, sizeof(buf)));
 377
 378         switch (rqstp->rq_authop->flavour) {
 379                 case RPC_AUTH_NULL:
 380                         if (rqstp->rq_proc != CB_NULL)
 381                                 ret = SVC_DENIED;
 382                         break;
 383                 case RPC_AUTH_UNIX:
 384                         break;
 385                 case RPC_AUTH_GSS:
 386                         ret = check_gss_callback_principal(clp, rqstp);
 387                         break;
 388                 default:
 389                         ret = SVC_DENIED;
 390         }
 391         nfs_put_client(clp);
 392         return ret;
 393 }
 394
 395 /*
 396  * Define NFS4 callback program
 397  */
 398 static struct svc_version *nfs4_callback_version[] = {
 399         [1] = &nfs4_callback_version1,
 400 };
 401
 402 static struct svc_stat nfs4_callback_stats;
 403
 404 static struct svc_program nfs4_callback_program = {
 405         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 406         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 407         .pg_vers = nfs4_callback_version,               /* version table */
 408         .pg_name = "NFSv4 callback",                    /* service name */
 409         .pg_class = "nfs",                              /* authentication class */
 410         .pg_stats = &nfs4_callback_stats,
 411         .pg_authenticate = nfs_callback_authenticate,
 412 };