fs/nfs/nfs4namespace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/nfs/nfs4namespace.c
   4  *
   5  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
   6  * - Modified by David Howells <dhowells@redhat.com>
   7  *
   8  * NFSv4 namespace
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/dcache.h>
  13 #include <linux/mount.h>
  14 #include <linux/namei.h>
  15 #include <linux/nfs_fs.h>
  16 #include <linux/nfs_mount.h>
  17 #include <linux/slab.h>
  18 #include <linux/string.h>
  19 #include <linux/sunrpc/clnt.h>
  20 #include <linux/sunrpc/addr.h>
  21 #include <linux/vfs.h>
  22 #include <linux/inet.h>
  23 #include "internal.h"
  24 #include "nfs4_fs.h"
  25 #include "nfs.h"
  26 #include "dns_resolve.h"
  27
  28 #define NFSDBG_FACILITY         NFSDBG_VFS
  29
  30 /*
  31  * Work out the length that an NFSv4 path would render to as a standard posix
  32  * path, with a leading slash but no terminating slash.
  33  */
  34 static ssize_t nfs4_pathname_len(const struct nfs4_pathname *pathname)
  35 {
  36         ssize_t len = 0;
  37         int i;
  38
  39         for (i = 0; i < pathname->ncomponents; i++) {
  40                 const struct nfs4_string *component = &pathname->components[i];
  41
  42                 if (component->len > NAME_MAX)
  43                         goto too_long;
  44                 len += 1 + component->len; /* Adding "/foo" */
  45                 if (len > PATH_MAX)
  46                         goto too_long;
  47         }
  48         return len;
  49
  50 too_long:
  51         return -ENAMETOOLONG;
  52 }
  53
  54 /*
  55  * Convert the NFSv4 pathname components into a standard posix path.
  56  */
  57 static char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  58                                   unsigned short *_len)
  59 {
  60         ssize_t len;
  61         char *buf, *p;
  62         int i;
  63
  64         len = nfs4_pathname_len(pathname);
  65         if (len < 0)
  66                 return ERR_PTR(len);
  67         *_len = len;
  68
  69         p = buf = kmalloc(len + 1, GFP_KERNEL);
  70         if (!buf)
  71                 return ERR_PTR(-ENOMEM);
  72
  73         for (i = 0; i < pathname->ncomponents; i++) {
  74                 const struct nfs4_string *component = &pathname->components[i];
  75
  76                 *p++ = '/';
  77                 memcpy(p, component->data, component->len);
  78                 p += component->len;
  79         }
  80
  81         *p = 0;
  82         return buf;
  83 }
  84
  85 /*
  86  * return the path component of "<server>:<path>"
  87  *  nfspath - the "<server>:<path>" string
  88  *  end - one past the last char that could contain "<server>:"
  89  * returns NULL on failure
  90  */
  91 static char *nfs_path_component(const char *nfspath, const char *end)
  92 {
  93         char *p;
  94
  95         if (*nfspath == '[') {
  96                 /* parse [] escaped IPv6 addrs */
  97                 p = strchr(nfspath, ']');
  98                 if (p != NULL && ++p < end && *p == ':')
  99                         return p + 1;
 100         } else {
 101                 /* otherwise split on first colon */
 102                 p = strchr(nfspath, ':');
 103                 if (p != NULL && p < end)
 104                         return p + 1;
 105         }
 106         return NULL;
 107 }
 108
 109 /*
 110  * Determine the mount path as a string
 111  */
 112 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
 113 {
 114         char *limit;
 115         char *path = nfs_path(&limit, dentry, buffer, buflen,
 116                               NFS_PATH_CANONICAL);
 117         if (!IS_ERR(path)) {
 118                 char *path_component = nfs_path_component(path, limit);
 119                 if (path_component)
 120                         return path_component;
 121         }
 122         return path;
 123 }
 124
 125 /*
 126  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
 127  * believe to be the server path to this dentry
 128  */
 129 static int nfs4_validate_fspath(struct dentry *dentry,
 130                                 const struct nfs4_fs_locations *locations,
 131                                 struct nfs_fs_context *ctx)
 132 {
 133         const char *path;
 134         char *fs_path;
 135         unsigned short len;
 136         char *buf;
 137         int n;
 138
 139         buf = kmalloc(4096, GFP_KERNEL);
 140         if (!buf)
 141                 return -ENOMEM;
 142
 143         path = nfs4_path(dentry, buf, 4096);
 144         if (IS_ERR(path)) {
 145                 kfree(buf);
 146                 return PTR_ERR(path);
 147         }
 148
 149         fs_path = nfs4_pathname_string(&locations->fs_path, &len);
 150         if (IS_ERR(fs_path)) {
 151                 kfree(buf);
 152                 return PTR_ERR(fs_path);
 153         }
 154
 155         n = strncmp(path, fs_path, len);
 156         kfree(buf);
 157         kfree(fs_path);
 158         if (n != 0) {
 159                 dprintk("%s: path %s does not begin with fsroot %s\n",
 160                         __func__, path, ctx->nfs_server.export_path);
 161                 return -ENOENT;
 162         }
 163
 164         return 0;
 165 }
 166
 167 static size_t nfs_parse_server_name(char *string, size_t len,
 168                 struct sockaddr *sa, size_t salen, struct net *net)
 169 {
 170         ssize_t ret;
 171
 172         ret = rpc_pton(net, string, len, sa, salen);
 173         if (ret == 0) {
 174                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
 175                 if (ret < 0)
 176                         ret = 0;
 177         }
 178         return ret;
 179 }
 180
 181 /**
 182  * nfs_find_best_sec - Find a security mechanism supported locally
 183  * @clnt: pointer to rpc_clnt
 184  * @server: NFS server struct
 185  * @flavors: List of security tuples returned by SECINFO procedure
 186  *
 187  * Return an rpc client that uses the first security mechanism in
 188  * "flavors" that is locally supported.  The "flavors" array
 189  * is searched in the order returned from the server, per RFC 3530
 190  * recommendation and each flavor is checked for membership in the
 191  * sec= mount option list if it exists.
 192  *
 193  * Return -EPERM if no matching flavor is found in the array.
 194  *
 195  * Please call rpc_shutdown_client() when you are done with this rpc client.
 196  *
 197  */
 198 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
 199                                           struct nfs_server *server,
 200                                           struct nfs4_secinfo_flavors *flavors)
 201 {
 202         rpc_authflavor_t pflavor;
 203         struct nfs4_secinfo4 *secinfo;
 204         unsigned int i;
 205
 206         for (i = 0; i < flavors->num_flavors; i++) {
 207                 secinfo = &flavors->flavors[i];
 208
 209                 switch (secinfo->flavor) {
 210                 case RPC_AUTH_NULL:
 211                 case RPC_AUTH_UNIX:
 212                 case RPC_AUTH_GSS:
 213                         pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
 214                                                         &secinfo->flavor_info);
 215                         /* does the pseudoflavor match a sec= mount opt? */
 216                         if (pflavor != RPC_AUTH_MAXFLAVOR &&
 217                             nfs_auth_info_match(&server->auth_info, pflavor)) {
 218                                 struct rpc_clnt *new;
 219                                 struct rpc_cred *cred;
 220
 221                                 /* Cloning creates an rpc_auth for the flavor */
 222                                 new = rpc_clone_client_set_auth(clnt, pflavor);
 223                                 if (IS_ERR(new))
 224                                         continue;
 225                                 /**
 226                                 * Check that the user actually can use the
 227                                 * flavor. This is mostly for RPC_AUTH_GSS
 228                                 * where cr_init obtains a gss context
 229                                 */
 230                                 cred = rpcauth_lookupcred(new->cl_auth, 0);
 231                                 if (IS_ERR(cred)) {
 232                                         rpc_shutdown_client(new);
 233                                         continue;
 234                                 }
 235                                 put_rpccred(cred);
 236                                 return new;
 237                         }
 238                 }
 239         }
 240         return ERR_PTR(-EPERM);
 241 }
 242
 243 /**
 244  * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
 245  * return an rpc_clnt that uses the best available security flavor with
 246  * respect to the secinfo flavor list and the sec= mount options.
 247  *
 248  * @clnt: RPC client to clone
 249  * @inode: directory inode
 250  * @name: lookup name
 251  *
 252  * Please call rpc_shutdown_client() when you are done with this rpc client.
 253  */
 254 struct rpc_clnt *
 255 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
 256                                         const struct qstr *name)
 257 {
 258         struct page *page;
 259         struct nfs4_secinfo_flavors *flavors;
 260         struct rpc_clnt *new;
 261         int err;
 262
 263         page = alloc_page(GFP_KERNEL);
 264         if (!page)
 265                 return ERR_PTR(-ENOMEM);
 266
 267         flavors = page_address(page);
 268
 269         err = nfs4_proc_secinfo(inode, name, flavors);
 270         if (err < 0) {
 271                 new = ERR_PTR(err);
 272                 goto out;
 273         }
 274
 275         new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
 276
 277 out:
 278         put_page(page);
 279         return new;
 280 }
 281
 282 static int try_location(struct fs_context *fc,
 283                         const struct nfs4_fs_location *location)
 284 {
 285         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 286         unsigned int len, s;
 287         char *export_path, *source, *p;
 288         int ret = -ENOENT;
 289
 290         /* Allocate a buffer big enough to hold any of the hostnames plus a
 291          * terminating char and also a buffer big enough to hold the hostname
 292          * plus a colon plus the path.
 293          */
 294         len = 0;
 295         for (s = 0; s < location->nservers; s++) {
 296                 const struct nfs4_string *buf = &location->servers[s];
 297                 if (buf->len > len)
 298                         len = buf->len;
 299         }
 300
 301         kfree(ctx->nfs_server.hostname);
 302         ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL);
 303         if (!ctx->nfs_server.hostname)
 304                 return -ENOMEM;
 305
 306         export_path = nfs4_pathname_string(&location->rootpath,
 307                                            &ctx->nfs_server.export_path_len);
 308         if (IS_ERR(export_path))
 309                 return PTR_ERR(export_path);
 310
 311         ctx->nfs_server.export_path = export_path;
 312
 313         source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
 314                          GFP_KERNEL);
 315         if (!source)
 316                 return -ENOMEM;
 317
 318         kfree(fc->source);
 319         fc->source = source;
 320         for (s = 0; s < location->nservers; s++) {
 321                 const struct nfs4_string *buf = &location->servers[s];
 322
 323                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 324                         continue;
 325
 326                 ctx->nfs_server.addrlen =
 327                         nfs_parse_server_name(buf->data, buf->len,
 328                                               &ctx->nfs_server.address,
 329                                               sizeof(ctx->nfs_server._address),
 330                                               fc->net_ns);
 331                 if (ctx->nfs_server.addrlen == 0)
 332                         continue;
 333
 334                 rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
 335
 336                 memcpy(ctx->nfs_server.hostname, buf->data, buf->len);
 337                 ctx->nfs_server.hostname[buf->len] = '\0';
 338
 339                 p = source;
 340                 memcpy(p, buf->data, buf->len);
 341                 p += buf->len;
 342                 *p++ = ':';
 343                 memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len);
 344                 p += ctx->nfs_server.export_path_len;
 345                 *p = 0;
 346
 347                 ret = nfs4_get_referral_tree(fc);
 348                 if (ret == 0)
 349                         return 0;
 350         }
 351
 352         return ret;
 353 }
 354
 355 /**
 356  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 357  * @dentry: parent directory
 358  * @locations: array of NFSv4 server location information
 359  *
 360  */
 361 static int nfs_follow_referral(struct fs_context *fc,
 362                                const struct nfs4_fs_locations *locations)
 363 {
 364         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 365         int loc, error;
 366
 367         if (locations == NULL || locations->nlocations <= 0)
 368                 return -ENOENT;
 369
 370         dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry);
 371
 372         /* Ensure fs path is a prefix of current dentry path */
 373         error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx);
 374         if (error < 0)
 375                 return error;
 376
 377         error = -ENOENT;
 378         for (loc = 0; loc < locations->nlocations; loc++) {
 379                 const struct nfs4_fs_location *location = &locations->locations[loc];
 380
 381                 if (location == NULL || location->nservers <= 0 ||
 382                     location->rootpath.ncomponents == 0)
 383                         continue;
 384
 385                 error = try_location(fc, location);
 386                 if (error == 0)
 387                         return 0;
 388         }
 389
 390         return error;
 391 }
 392
 393 /*
 394  * nfs_do_refmount - handle crossing a referral on server
 395  * @dentry - dentry of referral
 396  *
 397  */
 398 static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client)
 399 {
 400         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 401         struct dentry *dentry, *parent;
 402         struct nfs4_fs_locations *fs_locations = NULL;
 403         struct page *page;
 404         int err = -ENOMEM;
 405
 406         /* BUG_ON(IS_ROOT(dentry)); */
 407         page = alloc_page(GFP_KERNEL);
 408         if (!page)
 409                 return -ENOMEM;
 410
 411         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 412         if (!fs_locations)
 413                 goto out_free;
 414
 415         /* Get locations */
 416         dentry = ctx->clone_data.dentry;
 417         parent = dget_parent(dentry);
 418         dprintk("%s: getting locations for %pd2\n",
 419                 __func__, dentry);
 420
 421         err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
 422         dput(parent);
 423         if (err != 0)
 424                 goto out_free_2;
 425
 426         err = -ENOENT;
 427         if (fs_locations->nlocations <= 0 ||
 428             fs_locations->fs_path.ncomponents <= 0)
 429                 goto out_free_2;
 430
 431         err = nfs_follow_referral(fc, fs_locations);
 432 out_free_2:
 433         kfree(fs_locations);
 434 out_free:
 435         __free_page(page);
 436         return err;
 437 }
 438
 439 int nfs4_submount(struct fs_context *fc, struct nfs_server *server)
 440 {
 441         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 442         struct dentry *dentry = ctx->clone_data.dentry;
 443         struct dentry *parent = dget_parent(dentry);
 444         struct inode *dir = d_inode(parent);
 445         struct rpc_clnt *client;
 446         int ret;
 447
 448         /* Look it up again to get its attributes and sec flavor */
 449         client = nfs4_proc_lookup_mountpoint(dir, dentry, ctx->mntfh,
 450                                              ctx->clone_data.fattr);
 451         dput(parent);
 452         if (IS_ERR(client))
 453                 return PTR_ERR(client);
 454
 455         ctx->selected_flavor = client->cl_auth->au_flavor;
 456         if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 457                 ret = nfs_do_refmount(fc, client);
 458         } else {
 459                 ret = nfs_do_submount(fc);
 460         }
 461
 462         rpc_shutdown_client(client);
 463         return ret;
 464 }
 465
 466 /*
 467  * Try one location from the fs_locations array.
 468  *
 469  * Returns zero on success, or a negative errno value.
 470  */
 471 static int nfs4_try_replacing_one_location(struct nfs_server *server,
 472                 char *page, char *page2,
 473                 const struct nfs4_fs_location *location)
 474 {
 475         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 476         struct net *net = rpc_net_ns(server->client);
 477         struct sockaddr *sap;
 478         unsigned int s;
 479         size_t salen;
 480         int error;
 481
 482         sap = kmalloc(addr_bufsize, GFP_KERNEL);
 483         if (sap == NULL)
 484                 return -ENOMEM;
 485
 486         error = -ENOENT;
 487         for (s = 0; s < location->nservers; s++) {
 488                 const struct nfs4_string *buf = &location->servers[s];
 489                 char *hostname;
 490
 491                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
 492                         continue;
 493
 494                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
 495                         continue;
 496
 497                 salen = nfs_parse_server_name(buf->data, buf->len,
 498                                                 sap, addr_bufsize, net);
 499                 if (salen == 0)
 500                         continue;
 501                 rpc_set_port(sap, NFS_PORT);
 502
 503                 error = -ENOMEM;
 504                 hostname = kmemdup_nul(buf->data, buf->len, GFP_KERNEL);
 505                 if (hostname == NULL)
 506                         break;
 507
 508                 error = nfs4_update_server(server, hostname, sap, salen, net);
 509                 kfree(hostname);
 510                 if (error == 0)
 511                         break;
 512         }
 513
 514         kfree(sap);
 515         return error;
 516 }
 517
 518 /**
 519  * nfs4_replace_transport - set up transport to destination server
 520  *
 521  * @server: export being migrated
 522  * @locations: fs_locations array
 523  *
 524  * Returns zero on success, or a negative errno value.
 525  *
 526  * The client tries all the entries in the "locations" array, in the
 527  * order returned by the server, until one works or the end of the
 528  * array is reached.
 529  */
 530 int nfs4_replace_transport(struct nfs_server *server,
 531                            const struct nfs4_fs_locations *locations)
 532 {
 533         char *page = NULL, *page2 = NULL;
 534         int loc, error;
 535
 536         error = -ENOENT;
 537         if (locations == NULL || locations->nlocations <= 0)
 538                 goto out;
 539
 540         error = -ENOMEM;
 541         page = (char *) __get_free_page(GFP_USER);
 542         if (!page)
 543                 goto out;
 544         page2 = (char *) __get_free_page(GFP_USER);
 545         if (!page2)
 546                 goto out;
 547
 548         for (loc = 0; loc < locations->nlocations; loc++) {
 549                 const struct nfs4_fs_location *location =
 550                                                 &locations->locations[loc];
 551
 552                 if (location == NULL || location->nservers <= 0 ||
 553                     location->rootpath.ncomponents == 0)
 554                         continue;
 555
 556                 error = nfs4_try_replacing_one_location(server, page,
 557                                                         page2, location);
 558                 if (error == 0)
 559                         break;
 560         }
 561
 562 out:
 563         free_page((unsigned long)page);
 564         free_page((unsigned long)page2);
 565         return error;
 566 }