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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 static const int nfs_set_port_min = 0;
  42 static const int nfs_set_port_max = 65535;
  43
  44 /*
  45  * If the kernel has IPv6 support available, always listen for
  46  * both AF_INET and AF_INET6 requests.
  47  */
  48 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  49 static const sa_family_t        nfs_callback_family = AF_INET6;
  50 #else
  51 static const sa_family_t        nfs_callback_family = AF_INET;
  52 #endif
  53
  54 static int param_set_port(const char *val, struct kernel_param *kp)
  55 {
  56         char *endp;
  57         int num = simple_strtol(val, &endp, 0);
  58         if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
  59                 return -EINVAL;
  60         *((int *)kp->arg) = num;
  61         return 0;
  62 }
  63
  64 module_param_call(callback_tcpport, param_set_port, param_get_int,
  65                  &nfs_callback_set_tcpport, 0644);
  66
  67 /*
  68  * This is the callback kernel thread.
  69  */
  70 static int
  71 nfs_callback_svc(void *vrqstp)
  72 {
  73         int err, preverr = 0;
  74         struct svc_rqst *rqstp = vrqstp;
  75
  76         set_freezable();
  77
  78         /*
  79          * FIXME: do we really need to run this under the BKL? If so, please
  80          * add a comment about what it's intended to protect.
  81          */
  82         lock_kernel();
  83         while (!kthread_should_stop()) {
  84                 /*
  85                  * Listen for a request on the socket
  86                  */
  87                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
  88                 if (err == -EAGAIN || err == -EINTR) {
  89                         preverr = err;
  90                         continue;
  91                 }
  92                 if (err < 0) {
  93                         if (err != preverr) {
  94                                 printk(KERN_WARNING "%s: unexpected error "
  95                                         "from svc_recv (%d)\n", __func__, err);
  96                                 preverr = err;
  97                         }
  98                         schedule_timeout_uninterruptible(HZ);
  99                         continue;
 100                 }
 101                 preverr = err;
 102                 svc_process(rqstp);
 103         }
 104         unlock_kernel();
 105         return 0;
 106 }
 107
 108 /*
 109  * Bring up the callback thread if it is not already up.
 110  */
 111 int nfs_callback_up(void)
 112 {
 113         struct svc_serv *serv = NULL;
 114         int ret = 0;
 115
 116         mutex_lock(&nfs_callback_mutex);
 117         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
 118                 goto out;
 119         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
 120         ret = -ENOMEM;
 121         if (!serv)
 122                 goto out_err;
 123
 124         ret = svc_create_xprt(serv, "tcp", nfs_callback_family,
 125                                 nfs_callback_set_tcpport, 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 check_gss_callback_principal(struct nfs_client *clp,
 186                                         struct svc_rqst *rqstp)
 187 {
 188         struct rpc_clnt *r = clp->cl_rpcclient;
 189         char *p = svc_gss_principal(rqstp);
 190
 191         /*
 192          * It might just be a normal user principal, in which case
 193          * userspace won't bother to tell us the name at all.
 194          */
 195         if (p == NULL)
 196                 return SVC_DENIED;
 197
 198         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 199
 200         if (memcmp(p, "nfs@", 4) != 0)
 201                 return SVC_DENIED;
 202         p += 4;
 203         if (strcmp(p, r->cl_server) != 0)
 204                 return SVC_DENIED;
 205         return SVC_OK;
 206 }
 207
 208 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
 209 {
 210         struct nfs_client *clp;
 211         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 212         int ret = SVC_OK;
 213
 214         /* Don't talk to strangers */
 215         clp = nfs_find_client(svc_addr(rqstp), 4);
 216         if (clp == NULL)
 217                 return SVC_DROP;
 218
 219         dprintk("%s: %s NFSv4 callback!\n", __func__,
 220                         svc_print_addr(rqstp, buf, sizeof(buf)));
 221
 222         switch (rqstp->rq_authop->flavour) {
 223                 case RPC_AUTH_NULL:
 224                         if (rqstp->rq_proc != CB_NULL)
 225                                 ret = SVC_DENIED;
 226                         break;
 227                 case RPC_AUTH_UNIX:
 228                         break;
 229                 case RPC_AUTH_GSS:
 230                         ret = check_gss_callback_principal(clp, rqstp);
 231                         break;
 232                 default:
 233                         ret = SVC_DENIED;
 234         }
 235         nfs_put_client(clp);
 236         return ret;
 237 }
 238
 239 /*
 240  * Define NFS4 callback program
 241  */
 242 static struct svc_version *nfs4_callback_version[] = {
 243         [1] = &nfs4_callback_version1,
 244 };
 245
 246 static struct svc_stat nfs4_callback_stats;
 247
 248 static struct svc_program nfs4_callback_program = {
 249         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 250         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 251         .pg_vers = nfs4_callback_version,               /* version table */
 252         .pg_name = "NFSv4 callback",                    /* service name */
 253         .pg_class = "nfs",                              /* authentication class */
 254         .pg_stats = &nfs4_callback_stats,
 255         .pg_authenticate = nfs_callback_authenticate,
 256 };