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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
  19 #include <net/inet_sock.h>
  20
  21 #include "nfs4_fs.h"
  22 #include "callback.h"
  23 #include "internal.h"
  24
  25 #define NFSDBG_FACILITY NFSDBG_CALLBACK
  26
  27 struct nfs_callback_data {
  28         unsigned int users;
  29         struct svc_serv *serv;
  30         pid_t pid;
  31         struct completion started;
  32         struct completion stopped;
  33 };
  34
  35 static struct nfs_callback_data nfs_callback_info;
  36 static DEFINE_MUTEX(nfs_callback_mutex);
  37 static struct svc_program nfs4_callback_program;
  38
  39 unsigned int nfs_callback_set_tcpport;
  40 unsigned short nfs_callback_tcpport;
  41 static const int nfs_set_port_min = 0;
  42 static const int nfs_set_port_max = 65535;
  43
  44 static int param_set_port(const char *val, struct kernel_param *kp)
  45 {
  46         char *endp;
  47         int num = simple_strtol(val, &endp, 0);
  48         if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
  49                 return -EINVAL;
  50         *((int *)kp->arg) = num;
  51         return 0;
  52 }
  53
  54 module_param_call(callback_tcpport, param_set_port, param_get_int,
  55                  &nfs_callback_set_tcpport, 0644);
  56
  57 /*
  58  * This is the callback kernel thread.
  59  */
  60 static void nfs_callback_svc(struct svc_rqst *rqstp)
  61 {
  62         int err;
  63
  64         __module_get(THIS_MODULE);
  65         lock_kernel();
  66
  67         nfs_callback_info.pid = current->pid;
  68         daemonize("nfsv4-svc");
  69         /* Process request with signals blocked, but allow SIGKILL.  */
  70         allow_signal(SIGKILL);
  71         set_freezable();
  72
  73         complete(&nfs_callback_info.started);
  74
  75         for(;;) {
  76                 if (signalled()) {
  77                         if (nfs_callback_info.users == 0)
  78                                 break;
  79                         flush_signals(current);
  80                 }
  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                         continue;
  87                 if (err < 0) {
  88                         printk(KERN_WARNING
  89                                         "%s: terminating on error %d\n",
  90                                         __FUNCTION__, -err);
  91                         break;
  92                 }
  93                 svc_process(rqstp);
  94         }
  95
  96         svc_exit_thread(rqstp);
  97         nfs_callback_info.pid = 0;
  98         complete(&nfs_callback_info.stopped);
  99         unlock_kernel();
 100         module_put_and_exit(0);
 101 }
 102
 103 /*
 104  * Bring up the server process if it is not already up.
 105  */
 106 int nfs_callback_up(void)
 107 {
 108         struct svc_serv *serv = NULL;
 109         int ret = 0;
 110
 111         lock_kernel();
 112         mutex_lock(&nfs_callback_mutex);
 113         if (nfs_callback_info.users++ || nfs_callback_info.pid != 0)
 114                 goto out;
 115         init_completion(&nfs_callback_info.started);
 116         init_completion(&nfs_callback_info.stopped);
 117         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 118         ret = -ENOMEM;
 119         if (!serv)
 120                 goto out_err;
 121
 122         ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
 123                               SVC_SOCK_ANONYMOUS);
 124         if (ret <= 0)
 125                 goto out_err;
 126         nfs_callback_tcpport = ret;
 127         dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
 128
 129         ret = svc_create_thread(nfs_callback_svc, serv);
 130         if (ret < 0)
 131                 goto out_err;
 132         nfs_callback_info.serv = serv;
 133         wait_for_completion(&nfs_callback_info.started);
 134 out:
 135         /*
 136          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 137          * svc_create_thread increments that. So we need to call svc_destroy
 138          * on both success and failure so that the refcount is 1 when the
 139          * thread exits.
 140          */
 141         if (serv)
 142                 svc_destroy(serv);
 143         mutex_unlock(&nfs_callback_mutex);
 144         unlock_kernel();
 145         return ret;
 146 out_err:
 147         dprintk("Couldn't create callback socket or server thread; err = %d\n",
 148                 ret);
 149         nfs_callback_info.users--;
 150         goto out;
 151 }
 152
 153 /*
 154  * Kill the server process if it is not already up.
 155  */
 156 void nfs_callback_down(void)
 157 {
 158         lock_kernel();
 159         mutex_lock(&nfs_callback_mutex);
 160         nfs_callback_info.users--;
 161         do {
 162                 if (nfs_callback_info.users != 0 || nfs_callback_info.pid == 0)
 163                         break;
 164                 if (kill_proc(nfs_callback_info.pid, SIGKILL, 1) < 0)
 165                         break;
 166         } while (wait_for_completion_timeout(&nfs_callback_info.stopped, 5*HZ) == 0);
 167         mutex_unlock(&nfs_callback_mutex);
 168         unlock_kernel();
 169 }
 170
 171 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 172 {
 173         struct nfs_client *clp;
 174         char buf[RPC_MAX_ADDRBUFLEN];
 175
 176         /* Don't talk to strangers */
 177         clp = nfs_find_client(svc_addr(rqstp), 4);
 178         if (clp == NULL)
 179                 return SVC_DROP;
 180
 181         dprintk("%s: %s NFSv4 callback!\n", __FUNCTION__,
 182                         svc_print_addr(rqstp, buf, sizeof(buf)));
 183         nfs_put_client(clp);
 184
 185         switch (rqstp->rq_authop->flavour) {
 186                 case RPC_AUTH_NULL:
 187                         if (rqstp->rq_proc != CB_NULL)
 188                                 return SVC_DENIED;
 189                         break;
 190                 case RPC_AUTH_UNIX:
 191                         break;
 192                 case RPC_AUTH_GSS:
 193                         /* FIXME: RPCSEC_GSS handling? */
 194                 default:
 195                         return SVC_DENIED;
 196         }
 197         return SVC_OK;
 198 }
 199
 200 /*
 201  * Define NFS4 callback program
 202  */
 203 static struct svc_version *nfs4_callback_version[] = {
 204         [1] = &nfs4_callback_version1,
 205 };
 206
 207 static struct svc_stat nfs4_callback_stats;
 208
 209 static struct svc_program nfs4_callback_program = {
 210         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 211         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 212         .pg_vers = nfs4_callback_version,               /* version table */
 213         .pg_name = "NFSv4 callback",                    /* service name */
 214         .pg_class = "nfs",                              /* authentication class */
 215         .pg_stats = &nfs4_callback_stats,
 216         .pg_authenticate = nfs_callback_authenticate,
 217 };