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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_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 /*
  44  * If the kernel has IPv6 support available, always listen for
  45  * both AF_INET and AF_INET6 requests.
  46  */
  47 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  48 static const sa_family_t        nfs_callback_family = AF_INET6;
  49 #else
  50 static const sa_family_t        nfs_callback_family = AF_INET;
  51 #endif
  52
  53 static int param_set_port(const char *val, struct kernel_param *kp)
  54 {
  55         char *endp;
  56         int num = simple_strtol(val, &endp, 0);
  57         if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
  58                 return -EINVAL;
  59         *((int *)kp->arg) = num;
  60         return 0;
  61 }
  62
  63 module_param_call(callback_tcpport, param_set_port, param_get_int,
  64                  &nfs_callback_set_tcpport, 0644);
  65
  66 /*
  67  * This is the callback kernel thread.
  68  */
  69 static int
  70 nfs_callback_svc(void *vrqstp)
  71 {
  72         int err, preverr = 0;
  73         struct svc_rqst *rqstp = vrqstp;
  74
  75         set_freezable();
  76
  77         /*
  78          * FIXME: do we really need to run this under the BKL? If so, please
  79          * add a comment about what it's intended to protect.
  80          */
  81         lock_kernel();
  82         while (!kthread_should_stop()) {
  83                 /*
  84                  * Listen for a request on the socket
  85                  */
  86                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  87                 if (err == -EAGAIN || err == -EINTR) {
  88                         preverr = err;
  89                         continue;
  90                 }
  91                 if (err < 0) {
  92                         if (err != preverr) {
  93                                 printk(KERN_WARNING "%s: unexpected error "
  94                                         "from svc_recv (%d)\n", __func__, err);
  95                                 preverr = err;
  96                         }
  97                         schedule_timeout_uninterruptible(HZ);
  98                         continue;
  99                 }
 100                 preverr = err;
 101                 svc_process(rqstp);
 102         }
 103         unlock_kernel();
 104         return 0;
 105 }
 106
 107 /*
 108  * Bring up the callback thread if it is not already up.
 109  */
 110 int nfs_callback_up(void)
 111 {
 112         struct svc_serv *serv = NULL;
 113         int ret = 0;
 114
 115         mutex_lock(&nfs_callback_mutex);
 116         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
 117                 goto out;
 118         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE,
 119                                 nfs_callback_family, NULL);
 120         ret = -ENOMEM;
 121         if (!serv)
 122                 goto out_err;
 123
 124         ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
 125                               SVC_SOCK_ANONYMOUS);
 126         if (ret <= 0)
 127                 goto out_err;
 128         nfs_callback_tcpport = ret;
 129         dprintk("NFS: Callback listener port = %u (af %u)\n",
 130                         nfs_callback_tcpport, nfs_callback_family);
 131
 132         nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
 133         if (IS_ERR(nfs_callback_info.rqst)) {
 134                 ret = PTR_ERR(nfs_callback_info.rqst);
 135                 nfs_callback_info.rqst = NULL;
 136                 goto out_err;
 137         }
 138
 139         svc_sock_update_bufs(serv);
 140
 141         nfs_callback_info.task = kthread_run(nfs_callback_svc,
 142                                              nfs_callback_info.rqst,
 143                                              "nfsv4-svc");
 144         if (IS_ERR(nfs_callback_info.task)) {
 145                 ret = PTR_ERR(nfs_callback_info.task);
 146                 svc_exit_thread(nfs_callback_info.rqst);
 147                 nfs_callback_info.rqst = NULL;
 148                 nfs_callback_info.task = NULL;
 149                 goto out_err;
 150         }
 151 out:
 152         /*
 153          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 154          * svc_prepare_thread increments that. So we need to call svc_destroy
 155          * on both success and failure so that the refcount is 1 when the
 156          * thread exits.
 157          */
 158         if (serv)
 159                 svc_destroy(serv);
 160         mutex_unlock(&nfs_callback_mutex);
 161         return ret;
 162 out_err:
 163         dprintk("NFS: Couldn't create callback socket or server thread; "
 164                 "err = %d\n", ret);
 165         nfs_callback_info.users--;
 166         goto out;
 167 }
 168
 169 /*
 170  * Kill the callback thread if it's no longer being used.
 171  */
 172 void nfs_callback_down(void)
 173 {
 174         mutex_lock(&nfs_callback_mutex);
 175         nfs_callback_info.users--;
 176         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL) {
 177                 kthread_stop(nfs_callback_info.task);
 178                 svc_exit_thread(nfs_callback_info.rqst);
 179                 nfs_callback_info.rqst = NULL;
 180                 nfs_callback_info.task = NULL;
 181         }
 182         mutex_unlock(&nfs_callback_mutex);
 183 }
 184
 185 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 186 {
 187         struct nfs_client *clp;
 188         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 189
 190         /* Don't talk to strangers */
 191         clp = nfs_find_client(svc_addr(rqstp), 4);
 192         if (clp == NULL)
 193                 return SVC_DROP;
 194
 195         dprintk("%s: %s NFSv4 callback!\n", __func__,
 196                         svc_print_addr(rqstp, buf, sizeof(buf)));
 197         nfs_put_client(clp);
 198
 199         switch (rqstp->rq_authop->flavour) {
 200                 case RPC_AUTH_NULL:
 201                         if (rqstp->rq_proc != CB_NULL)
 202                                 return SVC_DENIED;
 203                         break;
 204                 case RPC_AUTH_UNIX:
 205                         break;
 206                 case RPC_AUTH_GSS:
 207                         /* FIXME: RPCSEC_GSS handling? */
 208                 default:
 209                         return SVC_DENIED;
 210         }
 211         return SVC_OK;
 212 }
 213
 214 /*
 215  * Define NFS4 callback program
 216  */
 217 static struct svc_version *nfs4_callback_version[] = {
 218         [1] = &nfs4_callback_version1,
 219 };
 220
 221 static struct svc_stat nfs4_callback_stats;
 222
 223 static struct svc_program nfs4_callback_program = {
 224         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 225         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 226         .pg_vers = nfs4_callback_version,               /* version table */
 227         .pg_name = "NFSv4 callback",                    /* service name */
 228         .pg_class = "nfs",                              /* authentication class */
 229         .pg_stats = &nfs4_callback_stats,
 230         .pg_authenticate = nfs_callback_authenticate,
 231 };