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