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
  20 #include <net/inet_sock.h>
  21
  22 #include "nfs4_fs.h"
  23 #include "callback.h"
  24 #include "internal.h"
  25
  26 #define NFSDBG_FACILITY NFSDBG_CALLBACK
  27
  28 struct nfs_callback_data {
  29         unsigned int users;
  30         struct svc_rqst *rqst;
  31         struct task_struct *task;
  32 };
  33
  34 static struct nfs_callback_data nfs_callback_info;
  35 static DEFINE_MUTEX(nfs_callback_mutex);
  36 static struct svc_program nfs4_callback_program;
  37
  38 unsigned int nfs_callback_set_tcpport;
  39 unsigned short nfs_callback_tcpport;
  40 static const int nfs_set_port_min = 0;
  41 static const int nfs_set_port_max = 65535;
  42
  43 static int param_set_port(const char *val, struct kernel_param *kp)
  44 {
  45         char *endp;
  46         int num = simple_strtol(val, &endp, 0);
  47         if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
  48                 return -EINVAL;
  49         *((int *)kp->arg) = num;
  50         return 0;
  51 }
  52
  53 module_param_call(callback_tcpport, param_set_port, param_get_int,
  54                  &nfs_callback_set_tcpport, 0644);
  55
  56 /*
  57  * This is the callback kernel thread.
  58  */
  59 static int
  60 nfs_callback_svc(void *vrqstp)
  61 {
  62         int err, preverr = 0;
  63         struct svc_rqst *rqstp = vrqstp;
  64
  65         set_freezable();
  66
  67         /*
  68          * FIXME: do we really need to run this under the BKL? If so, please
  69          * add a comment about what it's intended to protect.
  70          */
  71         lock_kernel();
  72         while (!kthread_should_stop()) {
  73                 /*
  74                  * Listen for a request on the socket
  75                  */
  76                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  77                 if (err == -EAGAIN || err == -EINTR) {
  78                         preverr = err;
  79                         continue;
  80                 }
  81                 if (err < 0) {
  82                         if (err != preverr) {
  83                                 printk(KERN_WARNING "%s: unexpected error "
  84                                         "from svc_recv (%d)\n", __func__, err);
  85                                 preverr = err;
  86                         }
  87                         schedule_timeout_uninterruptible(HZ);
  88                         continue;
  89                 }
  90                 preverr = err;
  91                 svc_process(rqstp);
  92         }
  93         unlock_kernel();
  94         return 0;
  95 }
  96
  97 /*
  98  * Bring up the callback thread if it is not already up.
  99  */
 100 int nfs_callback_up(void)
 101 {
 102         struct svc_serv *serv = NULL;
 103         int ret = 0;
 104
 105         mutex_lock(&nfs_callback_mutex);
 106         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
 107                 goto out;
 108         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 109         ret = -ENOMEM;
 110         if (!serv)
 111                 goto out_err;
 112
 113         ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
 114                               SVC_SOCK_ANONYMOUS);
 115         if (ret <= 0)
 116                 goto out_err;
 117         nfs_callback_tcpport = ret;
 118         dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
 119
 120         nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
 121         if (IS_ERR(nfs_callback_info.rqst)) {
 122                 ret = PTR_ERR(nfs_callback_info.rqst);
 123                 nfs_callback_info.rqst = NULL;
 124                 goto out_err;
 125         }
 126
 127         svc_sock_update_bufs(serv);
 128
 129         nfs_callback_info.task = kthread_run(nfs_callback_svc,
 130                                              nfs_callback_info.rqst,
 131                                              "nfsv4-svc");
 132         if (IS_ERR(nfs_callback_info.task)) {
 133                 ret = PTR_ERR(nfs_callback_info.task);
 134                 svc_exit_thread(nfs_callback_info.rqst);
 135                 nfs_callback_info.rqst = NULL;
 136                 nfs_callback_info.task = NULL;
 137                 goto out_err;
 138         }
 139 out:
 140         /*
 141          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 142          * svc_prepare_thread increments that. So we need to call svc_destroy
 143          * on both success and failure so that the refcount is 1 when the
 144          * thread exits.
 145          */
 146         if (serv)
 147                 svc_destroy(serv);
 148         mutex_unlock(&nfs_callback_mutex);
 149         return ret;
 150 out_err:
 151         dprintk("Couldn't create callback socket or server thread; err = %d\n",
 152                 ret);
 153         nfs_callback_info.users--;
 154         goto out;
 155 }
 156
 157 /*
 158  * Kill the callback thread if it's no longer being used.
 159  */
 160 void nfs_callback_down(void)
 161 {
 162         mutex_lock(&nfs_callback_mutex);
 163         nfs_callback_info.users--;
 164         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL) {
 165                 kthread_stop(nfs_callback_info.task);
 166                 svc_exit_thread(nfs_callback_info.rqst);
 167                 nfs_callback_info.rqst = NULL;
 168                 nfs_callback_info.task = NULL;
 169         }
 170         mutex_unlock(&nfs_callback_mutex);
 171 }
 172
 173 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 174 {
 175         struct nfs_client *clp;
 176         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 177
 178         /* Don't talk to strangers */
 179         clp = nfs_find_client(svc_addr(rqstp), 4);
 180         if (clp == NULL)
 181                 return SVC_DROP;
 182
 183         dprintk("%s: %s NFSv4 callback!\n", __func__,
 184                         svc_print_addr(rqstp, buf, sizeof(buf)));
 185         nfs_put_client(clp);
 186
 187         switch (rqstp->rq_authop->flavour) {
 188                 case RPC_AUTH_NULL:
 189                         if (rqstp->rq_proc != CB_NULL)
 190                                 return SVC_DENIED;
 191                         break;
 192                 case RPC_AUTH_UNIX:
 193                         break;
 194                 case RPC_AUTH_GSS:
 195                         /* FIXME: RPCSEC_GSS handling? */
 196                 default:
 197                         return SVC_DENIED;
 198         }
 199         return SVC_OK;
 200 }
 201
 202 /*
 203  * Define NFS4 callback program
 204  */
 205 static struct svc_version *nfs4_callback_version[] = {
 206         [1] = &nfs4_callback_version1,
 207 };
 208
 209 static struct svc_stat nfs4_callback_stats;
 210
 211 static struct svc_program nfs4_callback_program = {
 212         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 213         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 214         .pg_vers = nfs4_callback_version,               /* version table */
 215         .pg_name = "NFSv4 callback",                    /* service name */
 216         .pg_class = "nfs",                              /* authentication class */
 217         .pg_stats = &nfs4_callback_stats,
 218         .pg_authenticate = nfs_callback_authenticate,
 219 };