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