fs/nfs/callback.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/nfs/callback.c
   4  *
   5  * Copyright (C) 2004 Trond Myklebust
   6  *
   7  * NFSv4 callback handling
   8  */
   9
  10 #include <linux/completion.h>
  11 #include <linux/ip.h>
  12 #include <linux/module.h>
  13 #include <linux/sched/signal.h>
  14 #include <linux/sunrpc/svc.h>
  15 #include <linux/sunrpc/svcsock.h>
  16 #include <linux/nfs_fs.h>
  17 #include <linux/errno.h>
  18 #include <linux/mutex.h>
  19 #include <linux/freezer.h>
  20 #include <linux/sunrpc/svcauth_gss.h>
  21 #include <linux/sunrpc/bc_xprt.h>
  22
  23 #include <net/inet_sock.h>
  24
  25 #include "nfs4_fs.h"
  26 #include "callback.h"
  27 #include "internal.h"
  28 #include "netns.h"
  29
  30 #define NFSDBG_FACILITY NFSDBG_CALLBACK
  31
  32 struct nfs_callback_data {
  33         unsigned int users;
  34         struct svc_serv *serv;
  35 };
  36
  37 static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
  38 static DEFINE_MUTEX(nfs_callback_mutex);
  39 static struct svc_program nfs4_callback_program;
  40
  41 static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
  42 {
  43         const struct cred *cred = current_cred();
  44         int ret;
  45         struct nfs_net *nn = net_generic(net, nfs_net_id);
  46
  47         ret = svc_xprt_create(serv, "tcp", net, PF_INET,
  48                               nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
  49                               cred);
  50         if (ret <= 0)
  51                 goto out_err;
  52         nn->nfs_callback_tcpport = ret;
  53         dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
  54                 nn->nfs_callback_tcpport, PF_INET, net->ns.inum);
  55
  56         ret = svc_xprt_create(serv, "tcp", net, PF_INET6,
  57                               nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
  58                               cred);
  59         if (ret > 0) {
  60                 nn->nfs_callback_tcpport6 = ret;
  61                 dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
  62                         nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum);
  63         } else if (ret != -EAFNOSUPPORT)
  64                 goto out_err;
  65         return 0;
  66
  67 out_err:
  68         return (ret) ? ret : -ENOMEM;
  69 }
  70
  71 /*
  72  * This is the NFSv4 callback kernel thread.
  73  */
  74 static int
  75 nfs4_callback_svc(void *vrqstp)
  76 {
  77         struct svc_rqst *rqstp = vrqstp;
  78
  79         svc_thread_init_status(rqstp, 0);
  80
  81         set_freezable();
  82
  83         while (!svc_thread_should_stop(rqstp))
  84                 svc_recv(rqstp);
  85
  86         svc_exit_thread(rqstp);
  87         return 0;
  88 }
  89
  90 #if defined(CONFIG_NFS_V4_1)
  91 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
  92                 struct svc_serv *serv)
  93 {
  94         if (minorversion)
  95                 /*
  96                  * Save the svc_serv in the transport so that it can
  97                  * be referenced when the session backchannel is initialized
  98                  */
  99                 xprt->bc_serv = serv;
 100 }
 101 #else
 102 static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 103                 struct svc_serv *serv)
 104 {
 105 }
 106 #endif /* CONFIG_NFS_V4_1 */
 107
 108 static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
 109                                   struct svc_serv *serv)
 110 {
 111         int nrservs = nfs_callback_nr_threads;
 112         int ret;
 113
 114         nfs_callback_bc_serv(minorversion, xprt, serv);
 115
 116         if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
 117                 nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
 118
 119         if (serv->sv_nrthreads == nrservs)
 120                 return 0;
 121
 122         ret = svc_set_num_threads(serv, NULL, nrservs);
 123         if (ret) {
 124                 svc_set_num_threads(serv, NULL, 0);
 125                 return ret;
 126         }
 127         dprintk("nfs_callback_up: service started\n");
 128         return 0;
 129 }
 130
 131 static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
 132 {
 133         struct nfs_net *nn = net_generic(net, nfs_net_id);
 134
 135         if (--nn->cb_users[minorversion])
 136                 return;
 137
 138         dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
 139         svc_xprt_destroy_all(serv, net);
 140 }
 141
 142 static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
 143                                struct net *net, struct rpc_xprt *xprt)
 144 {
 145         struct nfs_net *nn = net_generic(net, nfs_net_id);
 146         int ret;
 147
 148         if (nn->cb_users[minorversion]++)
 149                 return 0;
 150
 151         dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);
 152
 153         ret = svc_bind(serv, net);
 154         if (ret < 0) {
 155                 printk(KERN_WARNING "NFS: bind callback service failed\n");
 156                 goto err_bind;
 157         }
 158
 159         ret = 0;
 160         if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
 161                 ret = nfs4_callback_up_net(serv, net);
 162         else if (xprt->ops->bc_setup)
 163                 set_bc_enabled(serv);
 164         else
 165                 ret = -EPROTONOSUPPORT;
 166
 167         if (ret < 0) {
 168                 printk(KERN_ERR "NFS: callback service start failed\n");
 169                 goto err_socks;
 170         }
 171         return 0;
 172
 173 err_socks:
 174         svc_rpcb_cleanup(serv, net);
 175 err_bind:
 176         nn->cb_users[minorversion]--;
 177         dprintk("NFS: Couldn't create callback socket: err = %d; "
 178                         "net = %x\n", ret, net->ns.inum);
 179         return ret;
 180 }
 181
 182 static struct svc_serv *nfs_callback_create_svc(int minorversion)
 183 {
 184         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 185         int (*threadfn)(void *data);
 186         struct svc_serv *serv;
 187
 188         /*
 189          * Check whether we're already up and running.
 190          */
 191         if (cb_info->serv)
 192                 return cb_info->serv;
 193
 194         /*
 195          * Sanity check: if there's no task,
 196          * we should be the first user ...
 197          */
 198         if (cb_info->users)
 199                 printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
 200                         cb_info->users);
 201
 202         threadfn = nfs4_callback_svc;
 203 #if !defined(CONFIG_NFS_V4_1)
 204         if (minorversion)
 205                 return ERR_PTR(-ENOTSUPP);
 206 #endif
 207         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE,
 208                           threadfn);
 209         if (!serv) {
 210                 printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
 211                 return ERR_PTR(-ENOMEM);
 212         }
 213         cb_info->serv = serv;
 214         dprintk("nfs_callback_create_svc: service created\n");
 215         return serv;
 216 }
 217
 218 /*
 219  * Bring up the callback thread if it is not already up.
 220  */
 221 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 222 {
 223         struct svc_serv *serv;
 224         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 225         int ret;
 226         struct net *net = xprt->xprt_net;
 227
 228         mutex_lock(&nfs_callback_mutex);
 229
 230         serv = nfs_callback_create_svc(minorversion);
 231         if (IS_ERR(serv)) {
 232                 ret = PTR_ERR(serv);
 233                 goto err_create;
 234         }
 235
 236         ret = nfs_callback_up_net(minorversion, serv, net, xprt);
 237         if (ret < 0)
 238                 goto err_net;
 239
 240         ret = nfs_callback_start_svc(minorversion, xprt, serv);
 241         if (ret < 0)
 242                 goto err_start;
 243
 244         cb_info->users++;
 245 err_net:
 246         if (!cb_info->users) {
 247                 svc_set_num_threads(cb_info->serv, NULL, 0);
 248                 svc_destroy(&cb_info->serv);
 249         }
 250 err_create:
 251         mutex_unlock(&nfs_callback_mutex);
 252         return ret;
 253
 254 err_start:
 255         nfs_callback_down_net(minorversion, serv, net);
 256         dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
 257         goto err_net;
 258 }
 259
 260 /*
 261  * Kill the callback thread if it's no longer being used.
 262  */
 263 void nfs_callback_down(int minorversion, struct net *net)
 264 {
 265         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 266         struct svc_serv *serv;
 267
 268         mutex_lock(&nfs_callback_mutex);
 269         serv = cb_info->serv;
 270         nfs_callback_down_net(minorversion, serv, net);
 271         cb_info->users--;
 272         if (cb_info->users == 0) {
 273                 svc_set_num_threads(serv, NULL, 0);
 274                 dprintk("nfs_callback_down: service destroyed\n");
 275                 svc_destroy(&cb_info->serv);
 276         }
 277         mutex_unlock(&nfs_callback_mutex);
 278 }
 279
 280 /* Boolean check of RPC_AUTH_GSS principal */
 281 int
 282 check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
 283 {
 284         char *p = rqstp->rq_cred.cr_principal;
 285
 286         if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
 287                 return 1;
 288
 289         /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
 290         if (clp->cl_minorversion != 0)
 291                 return 0;
 292         /*
 293          * It might just be a normal user principal, in which case
 294          * userspace won't bother to tell us the name at all.
 295          */
 296         if (p == NULL)
 297                 return 0;
 298
 299         /*
 300          * Did we get the acceptor from userland during the SETCLIENID
 301          * negotiation?
 302          */
 303         if (clp->cl_acceptor)
 304                 return !strcmp(p, clp->cl_acceptor);
 305
 306         /*
 307          * Otherwise try to verify it using the cl_hostname. Note that this
 308          * doesn't work if a non-canonical hostname was used in the devname.
 309          */
 310
 311         /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 312
 313         if (memcmp(p, "nfs@", 4) != 0)
 314                 return 0;
 315         p += 4;
 316         if (strcmp(p, clp->cl_hostname) != 0)
 317                 return 0;
 318         return 1;
 319 }
 320
 321 /*
 322  * pg_authenticate method for nfsv4 callback threads.
 323  *
 324  * The authflavor has been negotiated, so an incorrect flavor is a server
 325  * bug. Deny packets with incorrect authflavor.
 326  *
 327  * All other checking done after NFS decoding where the nfs_client can be
 328  * found in nfs4_callback_compound
 329  */
 330 static enum svc_auth_status nfs_callback_authenticate(struct svc_rqst *rqstp)
 331 {
 332         rqstp->rq_auth_stat = rpc_autherr_badcred;
 333
 334         switch (rqstp->rq_authop->flavour) {
 335         case RPC_AUTH_NULL:
 336                 if (rqstp->rq_proc != CB_NULL)
 337                         return SVC_DENIED;
 338                 break;
 339         case RPC_AUTH_GSS:
 340                 /* No RPC_AUTH_GSS support yet in NFSv4.1 */
 341                  if (svc_is_backchannel(rqstp))
 342                         return SVC_DENIED;
 343         }
 344
 345         rqstp->rq_auth_stat = rpc_auth_ok;
 346         return SVC_OK;
 347 }
 348
 349 /*
 350  * Define NFS4 callback program
 351  */
 352 static const struct svc_version *nfs4_callback_version[] = {
 353         [1] = &nfs4_callback_version1,
 354         [4] = &nfs4_callback_version4,
 355 };
 356
 357 static struct svc_program nfs4_callback_program = {
 358         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
 359         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
 360         .pg_vers = nfs4_callback_version,               /* version table */
 361         .pg_name = "NFSv4 callback",                    /* service name */
 362         .pg_class = "nfs",                              /* authentication class */
 363         .pg_authenticate = nfs_callback_authenticate,
 364         .pg_init_request = svc_generic_init_request,
 365         .pg_rpcbind_set = svc_generic_rpcbind_set,
 366 };