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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 #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         while (!kthread_should_stop()) {
  82                 /*
  83                  * Listen for a request on the socket
  84                  */
  85                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  86                 if (err == -EAGAIN || err == -EINTR) {
  87                         preverr = err;
  88                         continue;
  89                 }
  90                 if (err < 0) {
  91                         if (err != preverr) {
  92                                 printk(KERN_WARNING "%s: unexpected error "
  93                                         "from svc_recv (%d)\n", __func__, err);
  94                                 preverr = err;
  95                         }
  96                         schedule_timeout_uninterruptible(HZ);
  97                         continue;
  98                 }
  99                 preverr = err;
 100                 svc_process(rqstp);
 101         }
 102         return 0;
 103 }
 104
 105 /*
 106  * Prepare to bring up the NFSv4 callback service
 107  */
 108 struct svc_rqst *
 109 nfs4_callback_up(struct svc_serv *serv)
 110 {
 111         int ret;
 112
 113         ret = svc_create_xprt(serv, "tcp", PF_INET,
 114                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 115         if (ret <= 0)
 116                 goto out_err;
 117         nfs_callback_tcpport = ret;
 118         dprintk("NFS: Callback listener port = %u (af %u)\n",
 119                         nfs_callback_tcpport, PF_INET);
 120
 121 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 122         ret = svc_create_xprt(serv, "tcp", PF_INET6,
 123                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 124         if (ret > 0) {
 125                 nfs_callback_tcpport6 = ret;
 126                 dprintk("NFS: Callback listener port = %u (af %u)\n",
 127                                 nfs_callback_tcpport6, PF_INET6);
 128         } else if (ret == -EAFNOSUPPORT)
 129                 ret = 0;
 130         else
 131                 goto out_err;
 132 #endif  /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
 133
 134         return svc_prepare_thread(serv, &serv->sv_pools[0]);
 135
 136 out_err:
 137         if (ret == 0)
 138                 ret = -ENOMEM;
 139         return ERR_PTR(ret);
 140 }
 141
 142 #if defined(CONFIG_NFS_V4_1)
 143 /*
 144  * The callback service for NFSv4.1 callbacks
 145  */
 146 static int
 147 nfs41_callback_svc(void *vrqstp)
 148 {
 149         struct svc_rqst *rqstp = vrqstp;
 150         struct svc_serv *serv = rqstp->rq_server;
 151         struct rpc_rqst *req;
 152         int error;
 153         DEFINE_WAIT(wq);
 154
 155         set_freezable();
 156
 157         while (!kthread_should_stop()) {
 158                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
 159                 spin_lock_bh(&serv->sv_cb_lock);
 160                 if (!list_empty(&serv->sv_cb_list)) {
 161                         req = list_first_entry(&serv->sv_cb_list,
 162                                         struct rpc_rqst, rq_bc_list);
 163                         list_del(&req->rq_bc_list);
 164                         spin_unlock_bh(&serv->sv_cb_lock);
 165                         dprintk("Invoking bc_svc_process()\n");
 166                         error = bc_svc_process(serv, req, rqstp);
 167                         dprintk("bc_svc_process() returned w/ error code= %d\n",
 168                                 error);
 169                 } else {
 170                         spin_unlock_bh(&serv->sv_cb_lock);
 171                         schedule();
 172                 }
 173                 finish_wait(&serv->sv_cb_waitq, &wq);
 174         }
 175         return 0;
 176 }
 177
 178 /*
 179  * Bring up the NFSv4.1 callback service
 180  */
 181 struct svc_rqst *
 182 nfs41_callback_up(struct svc_serv *serv, struct rpc_xprt *xprt)
 183 {
 184         struct svc_xprt *bc_xprt;
 185         struct svc_rqst *rqstp = ERR_PTR(-ENOMEM);
 186
 187         dprintk("--> %s\n", __func__);
 188         /* Create a svc_sock for the service */
 189         bc_xprt = svc_sock_create(serv, xprt->prot);
 190         if (!bc_xprt)
 191                 goto out;
 192
 193         /*
 194          * Save the svc_serv in the transport so that it can
 195          * be referenced when the session backchannel is initialized
 196          */
 197         serv->bc_xprt = bc_xprt;
 198         xprt->bc_serv = serv;
 199
 200         INIT_LIST_HEAD(&serv->sv_cb_list);
 201         spin_lock_init(&serv->sv_cb_lock);
 202         init_waitqueue_head(&serv->sv_cb_waitq);
 203         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
 204         if (IS_ERR(rqstp))
 205                 svc_sock_destroy(bc_xprt);
 206 out:
 207         dprintk("--> %s return %p\n", __func__, rqstp);
 208         return rqstp;
 209 }
 210
 211 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 212                 struct svc_serv *serv, struct rpc_xprt *xprt,
 213                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 214 {
 215         if (minorversion) {
 216                 *rqstpp = nfs41_callback_up(serv, xprt);
 217                 *callback_svc = nfs41_callback_svc;
 218         }
 219         return minorversion;
 220 }
 221
 222 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 223                 struct nfs_callback_data *cb_info)
 224 {
 225         if (minorversion)
 226                 xprt->bc_serv = cb_info->serv;
 227 }
 228 #else
 229 static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
 230                 struct svc_serv *serv, struct rpc_xprt *xprt,
 231                 struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
 232 {
 233         return 0;
 234 }
 235
 236 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 237                 struct nfs_callback_data *cb_info)
 238 {
 239 }
 240 #endif /* CONFIG_NFS_V4_1 */
 241
 242 /*
 243  * Bring up the callback thread if it is not already up.
 244  */
 245 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 246 {
 247         struct svc_serv *serv = NULL;
 248         struct svc_rqst *rqstp;
 249         int (*callback_svc)(void *vrqstp);
 250         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 251         char svc_name[12];
 252         int ret = 0;
 253         int minorversion_setup;
 254
 255         mutex_lock(&nfs_callback_mutex);
 256         if (cb_info->users++ || cb_info->task != NULL) {
 257                 nfs_callback_bc_serv(minorversion, xprt, cb_info);
 258                 goto out;
 259         }
 260         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 261         if (!serv) {
 262                 ret = -ENOMEM;
 263                 goto out_err;
 264         }
 265
 266         minorversion_setup =  nfs_minorversion_callback_svc_setup(minorversion,
 267                                         serv, xprt, &rqstp, &callback_svc);
 268         if (!minorversion_setup) {
 269                 /* v4.0 callback setup */
 270                 rqstp = nfs4_callback_up(serv);
 271                 callback_svc = nfs4_callback_svc;
 272         }
 273
 274         if (IS_ERR(rqstp)) {
 275                 ret = PTR_ERR(rqstp);
 276                 goto out_err;
 277         }
 278
 279         svc_sock_update_bufs(serv);
 280
 281         sprintf(svc_name, "nfsv4.%u-svc", minorversion);
 282         cb_info->serv = serv;
 283         cb_info->rqst = rqstp;
 284         cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
 285         if (IS_ERR(cb_info->task)) {
 286                 ret = PTR_ERR(cb_info->task);
 287                 svc_exit_thread(cb_info->rqst);
 288                 cb_info->rqst = NULL;
 289                 cb_info->task = NULL;
 290                 goto out_err;
 291         }
 292 out:
 293         /*
 294          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 295          * svc_prepare_thread increments that. So we need to call svc_destroy
 296          * on both success and failure so that the refcount is 1 when the
 297          * thread exits.
 298          */
 299         if (serv)
 300                 svc_destroy(serv);
 301         mutex_unlock(&nfs_callback_mutex);
 302         return ret;
 303 out_err:
 304         dprintk("NFS: Couldn't create callback socket or server thread; "
 305                 "err = %d\n", ret);
 306         cb_info->users--;
 307         goto out;
 308 }
 309
 310 /*
 311  * Kill the callback thread if it's no longer being used.
 312  */
 313 void nfs_callback_down(int minorversion)
 314 {
 315         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 316
 317         mutex_lock(&nfs_callback_mutex);
 318         cb_info->users--;
 319         if (cb_info->users == 0 && cb_info->task != NULL) {
 320                 kthread_stop(cb_info->task);
 321                 svc_exit_thread(cb_info->rqst);
 322                 cb_info->serv = NULL;
 323                 cb_info->rqst = NULL;
 324                 cb_info->task = NULL;
 325         }
 326         mutex_unlock(&nfs_callback_mutex);
 327 }
 328
 329 static int check_gss_callback_principal(struct nfs_client *clp,
 330                                         struct svc_rqst *rqstp)
 331 {
 332         struct rpc_clnt *r = clp->cl_rpcclient;
 333         char *p = svc_gss_principal(rqstp);
 334
 335         /*
 336          * It might just be a normal user principal, in which case
 337          * userspace won't bother to tell us the name at all.
 338          */
 339         if (p == NULL)
 340                 return SVC_DENIED;
 341
 342         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 343
 344         if (memcmp(p, "nfs@", 4) != 0)
 345                 return SVC_DENIED;
 346         p += 4;
 347         if (strcmp(p, r->cl_server) != 0)
 348                 return SVC_DENIED;
 349         return SVC_OK;
 350 }
 351
 352 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 353 {
 354         struct nfs_client *clp;
 355         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 356         int ret = SVC_OK;
 357
 358         /* Don't talk to strangers */
 359         clp = nfs_find_client(svc_addr(rqstp), 4);
 360         if (clp == NULL)
 361                 return SVC_DROP;
 362
 363         dprintk("%s: %s NFSv4 callback!\n", __func__,
 364                         svc_print_addr(rqstp, buf, sizeof(buf)));
 365
 366         switch (rqstp->rq_authop->flavour) {
 367                 case RPC_AUTH_NULL:
 368                         if (rqstp->rq_proc != CB_NULL)
 369                                 ret = SVC_DENIED;
 370                         break;
 371                 case RPC_AUTH_UNIX:
 372                         break;
 373                 case RPC_AUTH_GSS:
 374                         ret = check_gss_callback_principal(clp, rqstp);
 375                         break;
 376                 default:
 377                         ret = SVC_DENIED;
 378         }
 379         nfs_put_client(clp);
 380         return ret;
 381 }
 382
 383 /*
 384  * Define NFS4 callback program
 385  */
 386 static struct svc_version *nfs4_callback_version[] = {
 387         [1] = &nfs4_callback_version1,
 388         [4] = &nfs4_callback_version4,
 389 };
 390
 391 static struct svc_stat nfs4_callback_stats;
 392
 393 static struct svc_program nfs4_callback_program = {
 394         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 395         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 396         .pg_vers = nfs4_callback_version,               /* version table */
 397         .pg_name = "NFSv4 callback",                    /* service name */
 398         .pg_class = "nfs",                              /* authentication class */
 399         .pg_stats = &nfs4_callback_stats,
 400         .pg_authenticate = nfs_callback_authenticate,
 401 };