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 #include <linux/sunrpc/svcauth_gss.h>
  20
  21 #include <net/inet_sock.h>
  22
  23 #include "nfs4_fs.h"
  24 #include "callback.h"
  25 #include "internal.h"
  26
  27 #define NFSDBG_FACILITY NFSDBG_CALLBACK
  28
  29 struct nfs_callback_data {
  30         unsigned int users;
  31         struct svc_rqst *rqst;
  32         struct task_struct *task;
  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 unsigned short nfs_callback_tcpport6;
  42 static const int nfs_set_port_min = 0;
  43 static const int nfs_set_port_max = 65535;
  44
  45 static int param_set_port(const char *val, struct kernel_param *kp)
  46 {
  47         char *endp;
  48         int num = simple_strtol(val, &endp, 0);
  49         if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
  50                 return -EINVAL;
  51         *((int *)kp->arg) = num;
  52         return 0;
  53 }
  54
  55 module_param_call(callback_tcpport, param_set_port, param_get_int,
  56                  &nfs_callback_set_tcpport, 0644);
  57
  58 /*
  59  * This is the callback kernel thread.
  60  */
  61 static int
  62 nfs_callback_svc(void *vrqstp)
  63 {
  64         int err, preverr = 0;
  65         struct svc_rqst *rqstp = vrqstp;
  66
  67         set_freezable();
  68
  69         /*
  70          * FIXME: do we really need to run this under the BKL? If so, please
  71          * add a comment about what it's intended to protect.
  72          */
  73         lock_kernel();
  74         while (!kthread_should_stop()) {
  75                 /*
  76                  * Listen for a request on the socket
  77                  */
  78                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  79                 if (err == -EAGAIN || err == -EINTR) {
  80                         preverr = err;
  81                         continue;
  82                 }
  83                 if (err < 0) {
  84                         if (err != preverr) {
  85                                 printk(KERN_WARNING "%s: unexpected error "
  86                                         "from svc_recv (%d)\n", __func__, err);
  87                                 preverr = err;
  88                         }
  89                         schedule_timeout_uninterruptible(HZ);
  90                         continue;
  91                 }
  92                 preverr = err;
  93                 svc_process(rqstp);
  94         }
  95         unlock_kernel();
  96         return 0;
  97 }
  98
  99 /*
 100  * Bring up the callback thread if it is not already up.
 101  */
 102 int nfs_callback_up(void)
 103 {
 104         struct svc_serv *serv = NULL;
 105         int ret = 0;
 106
 107         mutex_lock(&nfs_callback_mutex);
 108         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
 109                 goto out;
 110         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 111         ret = -ENOMEM;
 112         if (!serv)
 113                 goto out_err;
 114
 115         ret = svc_create_xprt(serv, "tcp", PF_INET,
 116                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 117         if (ret <= 0)
 118                 goto out_err;
 119         nfs_callback_tcpport = ret;
 120         dprintk("NFS: Callback listener port = %u (af %u)\n",
 121                         nfs_callback_tcpport, PF_INET);
 122
 123 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 124         ret = svc_create_xprt(serv, "tcp", PF_INET6,
 125                                 nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 126         if (ret > 0) {
 127                 nfs_callback_tcpport6 = ret;
 128                 dprintk("NFS: Callback listener port = %u (af %u)\n",
 129                                 nfs_callback_tcpport6, PF_INET6);
 130         } else if (ret == -EAFNOSUPPORT)
 131                 ret = 0;
 132         else
 133                 goto out_err;
 134 #endif  /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
 135
 136         nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
 137         if (IS_ERR(nfs_callback_info.rqst)) {
 138                 ret = PTR_ERR(nfs_callback_info.rqst);
 139                 nfs_callback_info.rqst = NULL;
 140                 goto out_err;
 141         }
 142
 143         svc_sock_update_bufs(serv);
 144
 145         nfs_callback_info.task = kthread_run(nfs_callback_svc,
 146                                              nfs_callback_info.rqst,
 147                                              "nfsv4-svc");
 148         if (IS_ERR(nfs_callback_info.task)) {
 149                 ret = PTR_ERR(nfs_callback_info.task);
 150                 svc_exit_thread(nfs_callback_info.rqst);
 151                 nfs_callback_info.rqst = NULL;
 152                 nfs_callback_info.task = NULL;
 153                 goto out_err;
 154         }
 155 out:
 156         /*
 157          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 158          * svc_prepare_thread increments that. So we need to call svc_destroy
 159          * on both success and failure so that the refcount is 1 when the
 160          * thread exits.
 161          */
 162         if (serv)
 163                 svc_destroy(serv);
 164         mutex_unlock(&nfs_callback_mutex);
 165         return ret;
 166 out_err:
 167         dprintk("NFS: Couldn't create callback socket or server thread; "
 168                 "err = %d\n", ret);
 169         nfs_callback_info.users--;
 170         goto out;
 171 }
 172
 173 /*
 174  * Kill the callback thread if it's no longer being used.
 175  */
 176 void nfs_callback_down(void)
 177 {
 178         mutex_lock(&nfs_callback_mutex);
 179         nfs_callback_info.users--;
 180         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL) {
 181                 kthread_stop(nfs_callback_info.task);
 182                 svc_exit_thread(nfs_callback_info.rqst);
 183                 nfs_callback_info.rqst = NULL;
 184                 nfs_callback_info.task = NULL;
 185         }
 186         mutex_unlock(&nfs_callback_mutex);
 187 }
 188
 189 static int check_gss_callback_principal(struct nfs_client *clp,
 190                                         struct svc_rqst *rqstp)
 191 {
 192         struct rpc_clnt *r = clp->cl_rpcclient;
 193         char *p = svc_gss_principal(rqstp);
 194
 195         /*
 196          * It might just be a normal user principal, in which case
 197          * userspace won't bother to tell us the name at all.
 198          */
 199         if (p == NULL)
 200                 return SVC_DENIED;
 201
 202         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 203
 204         if (memcmp(p, "nfs@", 4) != 0)
 205                 return SVC_DENIED;
 206         p += 4;
 207         if (strcmp(p, r->cl_server) != 0)
 208                 return SVC_DENIED;
 209         return SVC_OK;
 210 }
 211
 212 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 213 {
 214         struct nfs_client *clp;
 215         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 216         int ret = SVC_OK;
 217
 218         /* Don't talk to strangers */
 219         clp = nfs_find_client(svc_addr(rqstp), 4);
 220         if (clp == NULL)
 221                 return SVC_DROP;
 222
 223         dprintk("%s: %s NFSv4 callback!\n", __func__,
 224                         svc_print_addr(rqstp, buf, sizeof(buf)));
 225
 226         switch (rqstp->rq_authop->flavour) {
 227                 case RPC_AUTH_NULL:
 228                         if (rqstp->rq_proc != CB_NULL)
 229                                 ret = SVC_DENIED;
 230                         break;
 231                 case RPC_AUTH_UNIX:
 232                         break;
 233                 case RPC_AUTH_GSS:
 234                         ret = check_gss_callback_principal(clp, rqstp);
 235                         break;
 236                 default:
 237                         ret = SVC_DENIED;
 238         }
 239         nfs_put_client(clp);
 240         return ret;
 241 }
 242
 243 /*
 244  * Define NFS4 callback program
 245  */
 246 static struct svc_version *nfs4_callback_version[] = {
 247         [1] = &nfs4_callback_version1,
 248 };
 249
 250 static struct svc_stat nfs4_callback_stats;
 251
 252 static struct svc_program nfs4_callback_program = {
 253         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 254         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 255         .pg_vers = nfs4_callback_version,               /* version table */
 256         .pg_name = "NFSv4 callback",                    /* service name */
 257         .pg_class = "nfs",                              /* authentication class */
 258         .pg_stats = &nfs4_callback_stats,
 259         .pg_authenticate = nfs_callback_authenticate,
 260 };