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, const 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 static struct kernel_param_ops param_ops_portnr = {
  62         .set = param_set_portnr,
  63         .get = param_get_uint,
  64 };
  65 #define param_check_portnr(name, p) __param_check(name, p, unsigned int);
  66
  67 module_param_named(callback_tcpport, nfs_callback_set_tcpport, portnr, 0644);
  68
  69 /*
  70  * This is the NFSv4 callback kernel thread.
  71  */
  72 static int
  73 nfs4_callback_svc(void *vrqstp)
  74 {
  75         int err, preverr = 0;
  76         struct svc_rqst *rqstp = vrqstp;
  77
  78         set_freezable();
  79
  80         while (!kthread_should_stop()) {
  81                 /*
  82                  * Listen for a request on the socket
  83                  */
  84                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  85                 if (err == -EAGAIN || err == -EINTR) {
  86                         preverr = err;
  87                         continue;
  88                 }
  89                 if (err < 0) {
  90                         if (err != preverr) {
  91                                 printk(KERN_WARNING "%s: unexpected error "
  92                                         "from svc_recv (%d)\n", __func__, err);
  93                                 preverr = err;
  94                         }
  95                         schedule_timeout_uninterruptible(HZ);
  96                         continue;
  97                 }
  98                 preverr = err;
  99                 svc_process(rqstp);
 100         }
 101         return 0;
 102 }
 103
 104 /*
 105  * Prepare to bring up the NFSv4 callback service
 106  */
 107 struct svc_rqst *
 108 nfs4_callback_up(struct svc_serv *serv)
 109 {
 110         int ret;
 111
 112         ret = svc_create_xprt(serv, "tcp", PF_INET,
 113                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 114         if (ret <= 0)
 115                 goto out_err;
 116         nfs_callback_tcpport = ret;
 117         dprintk("NFS: Callback listener port = %u (af %u)\n",
 118                         nfs_callback_tcpport, PF_INET);
 119
 120         ret = svc_create_xprt(serv, "tcp", PF_INET6,
 121                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 122         if (ret > 0) {
 123                 nfs_callback_tcpport6 = ret;
 124                 dprintk("NFS: Callback listener port = %u (af %u)\n",
 125                                 nfs_callback_tcpport6, PF_INET6);
 126         } else if (ret == -EAFNOSUPPORT)
 127                 ret = 0;
 128         else
 129                 goto out_err;
 130
 131         return svc_prepare_thread(serv, &serv->sv_pools[0]);
 132
 133 out_err:
 134         if (ret == 0)
 135                 ret = -ENOMEM;
 136         return ERR_PTR(ret);
 137 }
 138
 139 #if defined(CONFIG_NFS_V4_1)
 140 /*
 141  * The callback service for NFSv4.1 callbacks
 142  */
 143 static int
 144 nfs41_callback_svc(void *vrqstp)
 145 {
 146         struct svc_rqst *rqstp = vrqstp;
 147         struct svc_serv *serv = rqstp->rq_server;
 148         struct rpc_rqst *req;
 149         int error;
 150         DEFINE_WAIT(wq);
 151
 152         set_freezable();
 153
 154         while (!kthread_should_stop()) {
 155                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
 156                 spin_lock_bh(&serv->sv_cb_lock);
 157                 if (!list_empty(&serv->sv_cb_list)) {
 158                         req = list_first_entry(&serv->sv_cb_list,
 159                                         struct rpc_rqst, rq_bc_list);
 160                         list_del(&req->rq_bc_list);
 161                         spin_unlock_bh(&serv->sv_cb_lock);
 162                         dprintk("Invoking bc_svc_process()\n");
 163                         error = bc_svc_process(serv, req, rqstp);
 164                         dprintk("bc_svc_process() returned w/ error code= %d\n",
 165                                 error);
 166                 } else {
 167                         spin_unlock_bh(&serv->sv_cb_lock);
 168                         schedule();
 169                 }
 170                 finish_wait(&serv->sv_cb_waitq, &wq);
 171         }
 172         return 0;
 173 }
 174
 175 /*
 176  * Bring up the NFSv4.1 callback service
 177  */
 178 struct svc_rqst *
 179 nfs41_callback_up(struct svc_serv *serv, struct rpc_xprt *xprt)
 180 {
 181         struct svc_xprt *bc_xprt;
 182         struct svc_rqst *rqstp = ERR_PTR(-ENOMEM);
 183
 184         dprintk("--> %s\n", __func__);
 185         /* Create a svc_sock for the service */
 186         bc_xprt = svc_sock_create(serv, xprt->prot);
 187         if (!bc_xprt)
 188                 goto out;
 189
 190         /*
 191          * Save the svc_serv in the transport so that it can
 192          * be referenced when the session backchannel is initialized
 193          */
 194         serv->bc_xprt = bc_xprt;
 195         xprt->bc_serv = serv;
 196
 197         INIT_LIST_HEAD(&serv->sv_cb_list);
 198         spin_lock_init(&serv->sv_cb_lock);
 199         init_waitqueue_head(&serv->sv_cb_waitq);
 200         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
 201         if (IS_ERR(rqstp))
 202                 svc_sock_destroy(bc_xprt);
 203 out:
 204         dprintk("--> %s return %p\n", __func__, rqstp);
 205         return rqstp;
 206 }
 207
 208 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 209                 struct svc_serv *serv, struct rpc_xprt *xprt,
 210                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 211 {
 212         if (minorversion) {
 213                 *rqstpp = nfs41_callback_up(serv, xprt);
 214                 *callback_svc = nfs41_callback_svc;
 215         }
 216         return minorversion;
 217 }
 218
 219 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 220                 struct nfs_callback_data *cb_info)
 221 {
 222         if (minorversion)
 223                 xprt->bc_serv = cb_info->serv;
 224 }
 225 #else
 226 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 227                 struct svc_serv *serv, struct rpc_xprt *xprt,
 228                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 229 {
 230         return 0;
 231 }
 232
 233 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 234                 struct nfs_callback_data *cb_info)
 235 {
 236 }
 237 #endif /* CONFIG_NFS_V4_1 */
 238
 239 /*
 240  * Bring up the callback thread if it is not already up.
 241  */
 242 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 243 {
 244         struct svc_serv *serv = NULL;
 245         struct svc_rqst *rqstp;
 246         int (*callback_svc)(void *vrqstp);
 247         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 248         char svc_name[12];
 249         int ret = 0;
 250         int minorversion_setup;
 251
 252         mutex_lock(&nfs_callback_mutex);
 253         if (cb_info->users++ || cb_info->task != NULL) {
 254                 nfs_callback_bc_serv(minorversion, xprt, cb_info);
 255                 goto out;
 256         }
 257         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 258         if (!serv) {
 259                 ret = -ENOMEM;
 260                 goto out_err;
 261         }
 262
 263         minorversion_setup =  nfs_minorversion_callback_svc_setup(minorversion,
 264                                         serv, xprt, &rqstp, &callback_svc);
 265         if (!minorversion_setup) {
 266                 /* v4.0 callback setup */
 267                 rqstp = nfs4_callback_up(serv);
 268                 callback_svc = nfs4_callback_svc;
 269         }
 270
 271         if (IS_ERR(rqstp)) {
 272                 ret = PTR_ERR(rqstp);
 273                 goto out_err;
 274         }
 275
 276         svc_sock_update_bufs(serv);
 277
 278         sprintf(svc_name, "nfsv4.%u-svc", minorversion);
 279         cb_info->serv = serv;
 280         cb_info->rqst = rqstp;
 281         cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
 282         if (IS_ERR(cb_info->task)) {
 283                 ret = PTR_ERR(cb_info->task);
 284                 svc_exit_thread(cb_info->rqst);
 285                 cb_info->rqst = NULL;
 286                 cb_info->task = NULL;
 287                 goto out_err;
 288         }
 289 out:
 290         /*
 291          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 292          * svc_prepare_thread increments that. So we need to call svc_destroy
 293          * on both success and failure so that the refcount is 1 when the
 294          * thread exits.
 295          */
 296         if (serv)
 297                 svc_destroy(serv);
 298         mutex_unlock(&nfs_callback_mutex);
 299         return ret;
 300 out_err:
 301         dprintk("NFS: Couldn't create callback socket or server thread; "
 302                 "err = %d\n", ret);
 303         cb_info->users--;
 304         goto out;
 305 }
 306
 307 /*
 308  * Kill the callback thread if it's no longer being used.
 309  */
 310 void nfs_callback_down(int minorversion)
 311 {
 312         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 313
 314         mutex_lock(&nfs_callback_mutex);
 315         cb_info->users--;
 316         if (cb_info->users == 0 && cb_info->task != NULL) {
 317                 kthread_stop(cb_info->task);
 318                 svc_exit_thread(cb_info->rqst);
 319                 cb_info->serv = NULL;
 320                 cb_info->rqst = NULL;
 321                 cb_info->task = NULL;
 322         }
 323         mutex_unlock(&nfs_callback_mutex);
 324 }
 325
 326 static int check_gss_callback_principal(struct nfs_client *clp,
 327                                         struct svc_rqst *rqstp)
 328 {
 329         struct rpc_clnt *r = clp->cl_rpcclient;
 330         char *p = svc_gss_principal(rqstp);
 331
 332         /*
 333          * It might just be a normal user principal, in which case
 334          * userspace won't bother to tell us the name at all.
 335          */
 336         if (p == NULL)
 337                 return SVC_DENIED;
 338
 339         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 340
 341         if (memcmp(p, "nfs@", 4) != 0)
 342                 return SVC_DENIED;
 343         p += 4;
 344         if (strcmp(p, r->cl_server) != 0)
 345                 return SVC_DENIED;
 346         return SVC_OK;
 347 }
 348
 349 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 350 {
 351         struct nfs_client *clp;
 352         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 353         int ret = SVC_OK;
 354
 355         /* Don't talk to strangers */
 356         clp = nfs_find_client(svc_addr(rqstp), 4);
 357         if (clp == NULL)
 358                 return SVC_DROP;
 359
 360         dprintk("%s: %s NFSv4 callback!\n", __func__,
 361                         svc_print_addr(rqstp, buf, sizeof(buf)));
 362
 363         switch (rqstp->rq_authop->flavour) {
 364                 case RPC_AUTH_NULL:
 365                         if (rqstp->rq_proc != CB_NULL)
 366                                 ret = SVC_DENIED;
 367                         break;
 368                 case RPC_AUTH_UNIX:
 369                         break;
 370                 case RPC_AUTH_GSS:
 371                         ret = check_gss_callback_principal(clp, rqstp);
 372                         break;
 373                 default:
 374                         ret = SVC_DENIED;
 375         }
 376         nfs_put_client(clp);
 377         return ret;
 378 }
 379
 380 /*
 381  * Define NFS4 callback program
 382  */
 383 static struct svc_version *nfs4_callback_version[] = {
 384         [1] = &nfs4_callback_version1,
 385         [4] = &nfs4_callback_version4,
 386 };
 387
 388 static struct svc_stat nfs4_callback_stats;
 389
 390 static struct svc_program nfs4_callback_program = {
 391         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 392         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 393         .pg_vers = nfs4_callback_version,               /* version table */
 394         .pg_name = "NFSv4 callback",                    /* service name */
 395         .pg_class = "nfs",                              /* authentication class */
 396         .pg_stats = &nfs4_callback_stats,
 397         .pg_authenticate = nfs_callback_authenticate,
 398 };