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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 #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                 goto out_err;
 132 #endif  /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
 133
 134         nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
 135         if (IS_ERR(nfs_callback_info.rqst)) {
 136                 ret = PTR_ERR(nfs_callback_info.rqst);
 137                 nfs_callback_info.rqst = NULL;
 138                 goto out_err;
 139         }
 140
 141         svc_sock_update_bufs(serv);
 142
 143         nfs_callback_info.task = kthread_run(nfs_callback_svc,
 144                                              nfs_callback_info.rqst,
 145                                              "nfsv4-svc");
 146         if (IS_ERR(nfs_callback_info.task)) {
 147                 ret = PTR_ERR(nfs_callback_info.task);
 148                 svc_exit_thread(nfs_callback_info.rqst);
 149                 nfs_callback_info.rqst = NULL;
 150                 nfs_callback_info.task = NULL;
 151                 goto out_err;
 152         }
 153 out:
 154         /*
 155          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
 156          * svc_prepare_thread increments that. So we need to call svc_destroy
 157          * on both success and failure so that the refcount is 1 when the
 158          * thread exits.
 159          */
 160         if (serv)
 161                 svc_destroy(serv);
 162         mutex_unlock(&nfs_callback_mutex);
 163         return ret;
 164 out_err:
 165         dprintk("NFS: Couldn't create callback socket or server thread; "
 166                 "err = %d\n", ret);
 167         nfs_callback_info.users--;
 168         goto out;
 169 }
 170
 171 /*
 172  * Kill the callback thread if it's no longer being used.
 173  */
 174 void nfs_callback_down(void)
 175 {
 176         mutex_lock(&nfs_callback_mutex);
 177         nfs_callback_info.users--;
 178         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL) {
 179                 kthread_stop(nfs_callback_info.task);
 180                 svc_exit_thread(nfs_callback_info.rqst);
 181                 nfs_callback_info.rqst = NULL;
 182                 nfs_callback_info.task = NULL;
 183         }
 184         mutex_unlock(&nfs_callback_mutex);
 185 }
 186
 187 static int check_gss_callback_principal(struct nfs_client *clp,
 188                                         struct svc_rqst *rqstp)
 189 {
 190         struct rpc_clnt *r = clp->cl_rpcclient;
 191         char *p = svc_gss_principal(rqstp);
 192
 193         /*
 194          * It might just be a normal user principal, in which case
 195          * userspace won't bother to tell us the name at all.
 196          */
 197         if (p == NULL)
 198                 return SVC_DENIED;
 199
 200         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 201
 202         if (memcmp(p, "nfs@", 4) != 0)
 203                 return SVC_DENIED;
 204         p += 4;
 205         if (strcmp(p, r->cl_server) != 0)
 206                 return SVC_DENIED;
 207         return SVC_OK;
 208 }
 209
 210 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 211 {
 212         struct nfs_client *clp;
 213         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 214         int ret = SVC_OK;
 215
 216         /* Don't talk to strangers */
 217         clp = nfs_find_client(svc_addr(rqstp), 4);
 218         if (clp == NULL)
 219                 return SVC_DROP;
 220
 221         dprintk("%s: %s NFSv4 callback!\n", __func__,
 222                         svc_print_addr(rqstp, buf, sizeof(buf)));
 223
 224         switch (rqstp->rq_authop->flavour) {
 225                 case RPC_AUTH_NULL:
 226                         if (rqstp->rq_proc != CB_NULL)
 227                                 ret = SVC_DENIED;
 228                         break;
 229                 case RPC_AUTH_UNIX:
 230                         break;
 231                 case RPC_AUTH_GSS:
 232                         ret = check_gss_callback_principal(clp, rqstp);
 233                         break;
 234                 default:
 235                         ret = SVC_DENIED;
 236         }
 237         nfs_put_client(clp);
 238         return ret;
 239 }
 240
 241 /*
 242  * Define NFS4 callback program
 243  */
 244 static struct svc_version *nfs4_callback_version[] = {
 245         [1] = &nfs4_callback_version1,
 246 };
 247
 248 static struct svc_stat nfs4_callback_stats;
 249
 250 static struct svc_program nfs4_callback_program = {
 251         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 252         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 253         .pg_vers = nfs4_callback_version,               /* version table */
 254         .pg_name = "NFSv4 callback",                    /* service name */
 255         .pg_class = "nfs",                              /* authentication class */
 256         .pg_stats = &nfs4_callback_stats,
 257         .pg_authenticate = nfs_callback_authenticate,
 258 };