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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
  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_serv *serv;
  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         nfs_callback_info.task = NULL;
  95         svc_exit_thread(rqstp);
  96         return 0;
  97 }
  98
  99 /*
 100  * Bring up the server process if it is not already up.
 101  */
 102 int nfs_callback_up(void)
 103 {
 104         struct svc_serv *serv = NULL;
 105         struct svc_rqst *rqstp;
 106         int ret = 0;
 107
 108         lock_kernel();
 109         mutex_lock(&nfs_callback_mutex);
 110         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
 111                 goto out;
 112         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 113         ret = -ENOMEM;
 114         if (!serv)
 115                 goto out_err;
 116
 117         ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
 118                               SVC_SOCK_ANONYMOUS);
 119         if (ret <= 0)
 120                 goto out_err;
 121         nfs_callback_tcpport = ret;
 122         dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
 123
 124         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
 125         if (IS_ERR(rqstp)) {
 126                 ret = PTR_ERR(rqstp);
 127                 goto out_err;
 128         }
 129
 130         svc_sock_update_bufs(serv);
 131         nfs_callback_info.serv = serv;
 132
 133         nfs_callback_info.task = kthread_run(nfs_callback_svc, rqstp,
 134                                              "nfsv4-svc");
 135         if (IS_ERR(nfs_callback_info.task)) {
 136                 ret = PTR_ERR(nfs_callback_info.task);
 137                 nfs_callback_info.serv = NULL;
 138                 nfs_callback_info.task = NULL;
 139                 svc_exit_thread(rqstp);
 140                 goto out_err;
 141         }
 142 out:
 143         /*
 144          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 145          * svc_prepare_thread increments that. So we need to call svc_destroy
 146          * on both success and failure so that the refcount is 1 when the
 147          * thread exits.
 148          */
 149         if (serv)
 150                 svc_destroy(serv);
 151         mutex_unlock(&nfs_callback_mutex);
 152         unlock_kernel();
 153         return ret;
 154 out_err:
 155         dprintk("Couldn't create callback socket or server thread; err = %d\n",
 156                 ret);
 157         nfs_callback_info.users--;
 158         goto out;
 159 }
 160
 161 /*
 162  * Kill the server process if it is not already down.
 163  */
 164 void nfs_callback_down(void)
 165 {
 166         lock_kernel();
 167         mutex_lock(&nfs_callback_mutex);
 168         nfs_callback_info.users--;
 169         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL)
 170                 kthread_stop(nfs_callback_info.task);
 171         mutex_unlock(&nfs_callback_mutex);
 172         unlock_kernel();
 173 }
 174
 175 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 176 {
 177         struct nfs_client *clp;
 178         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 179
 180         /* Don't talk to strangers */
 181         clp = nfs_find_client(svc_addr(rqstp), 4);
 182         if (clp == NULL)
 183                 return SVC_DROP;
 184
 185         dprintk("%s: %s NFSv4 callback!\n", __func__,
 186                         svc_print_addr(rqstp, buf, sizeof(buf)));
 187         nfs_put_client(clp);
 188
 189         switch (rqstp->rq_authop->flavour) {
 190                 case RPC_AUTH_NULL:
 191                         if (rqstp->rq_proc != CB_NULL)
 192                                 return SVC_DENIED;
 193                         break;
 194                 case RPC_AUTH_UNIX:
 195                         break;
 196                 case RPC_AUTH_GSS:
 197                         /* FIXME: RPCSEC_GSS handling? */
 198                 default:
 199                         return SVC_DENIED;
 200         }
 201         return SVC_OK;
 202 }
 203
 204 /*
 205  * Define NFS4 callback program
 206  */
 207 static struct svc_version *nfs4_callback_version[] = {
 208         [1] = &nfs4_callback_version1,
 209 };
 210
 211 static struct svc_stat nfs4_callback_stats;
 212
 213 static struct svc_program nfs4_callback_program = {
 214         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 215         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 216         .pg_vers = nfs4_callback_version,               /* version table */
 217         .pg_name = "NFSv4 callback",                    /* service name */
 218         .pg_class = "nfs",                              /* authentication class */
 219         .pg_stats = &nfs4_callback_stats,
 220         .pg_authenticate = nfs_callback_authenticate,
 221 };