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 size_t nfs_parse_server_name(char *string, size_t len, struct sockaddr_storage *ss,
 168                              size_t salen, struct net *net, int port)
 169 {
 170         struct sockaddr *sa = (struct sockaddr *)ss;
 171         ssize_t ret;
 172
 173         ret = rpc_pton(net, string, len, sa, salen);
 174         if (ret == 0) {
 175                 ret = rpc_uaddr2sockaddr(net, string, len, sa, salen);
 176                 if (ret == 0) {
 177                         ret = nfs_dns_resolve_name(net, string, len, ss, salen);
 178                         if (ret < 0)
 179                                 ret = 0;
 180                 }
 181         } else if (port) {
 182                 rpc_set_port(sa, port);
 183         }
 184         return ret;
 185 }
 186
 187 /**
 188  * nfs_find_best_sec - Find a security mechanism supported locally
 189  * @clnt: pointer to rpc_clnt
 190  * @server: NFS server struct
 191  * @flavors: List of security tuples returned by SECINFO procedure
 192  *
 193  * Return an rpc client that uses the first security mechanism in
 194  * "flavors" that is locally supported.  The "flavors" array
 195  * is searched in the order returned from the server, per RFC 3530
 196  * recommendation and each flavor is checked for membership in the
 197  * sec= mount option list if it exists.
 198  *
 199  * Return -EPERM if no matching flavor is found in the array.
 200  *
 201  * Please call rpc_shutdown_client() when you are done with this rpc client.
 202  *
 203  */
 204 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
 205                                           struct nfs_server *server,
 206                                           struct nfs4_secinfo_flavors *flavors)
 207 {
 208         rpc_authflavor_t pflavor;
 209         struct nfs4_secinfo4 *secinfo;
 210         unsigned int i;
 211
 212         for (i = 0; i < flavors->num_flavors; i++) {
 213                 secinfo = &flavors->flavors[i];
 214
 215                 switch (secinfo->flavor) {
 216                 case RPC_AUTH_NULL:
 217                 case RPC_AUTH_UNIX:
 218                 case RPC_AUTH_GSS:
 219                         pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
 220                                                         &secinfo->flavor_info);
 221                         /* does the pseudoflavor match a sec= mount opt? */
 222                         if (pflavor != RPC_AUTH_MAXFLAVOR &&
 223                             nfs_auth_info_match(&server->auth_info, pflavor)) {
 224                                 struct rpc_clnt *new;
 225                                 struct rpc_cred *cred;
 226
 227                                 /* Cloning creates an rpc_auth for the flavor */
 228                                 new = rpc_clone_client_set_auth(clnt, pflavor);
 229                                 if (IS_ERR(new))
 230                                         continue;
 231                                 /**
 232                                 * Check that the user actually can use the
 233                                 * flavor. This is mostly for RPC_AUTH_GSS
 234                                 * where cr_init obtains a gss context
 235                                 */
 236                                 cred = rpcauth_lookupcred(new->cl_auth, 0);
 237                                 if (IS_ERR(cred)) {
 238                                         rpc_shutdown_client(new);
 239                                         continue;
 240                                 }
 241                                 put_rpccred(cred);
 242                                 return new;
 243                         }
 244                 }
 245         }
 246         return ERR_PTR(-EPERM);
 247 }
 248
 249 /**
 250  * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
 251  * return an rpc_clnt that uses the best available security flavor with
 252  * respect to the secinfo flavor list and the sec= mount options.
 253  *
 254  * @clnt: RPC client to clone
 255  * @inode: directory inode
 256  * @name: lookup name
 257  *
 258  * Please call rpc_shutdown_client() when you are done with this rpc client.
 259  */
 260 struct rpc_clnt *
 261 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
 262                                         const struct qstr *name)
 263 {
 264         struct page *page;
 265         struct nfs4_secinfo_flavors *flavors;
 266         struct rpc_clnt *new;
 267         int err;
 268
 269         page = alloc_page(GFP_KERNEL);
 270         if (!page)
 271                 return ERR_PTR(-ENOMEM);
 272
 273         flavors = page_address(page);
 274
 275         err = nfs4_proc_secinfo(inode, name, flavors);
 276         if (err < 0) {
 277                 new = ERR_PTR(err);
 278                 goto out;
 279         }
 280
 281         new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
 282
 283 out:
 284         put_page(page);
 285         return new;
 286 }
 287
 288 static int try_location(struct fs_context *fc,
 289                         const struct nfs4_fs_location *location)
 290 {
 291         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 292         unsigned int len, s;
 293         char *export_path, *source, *p;
 294         int ret = -ENOENT;
 295
 296         /* Allocate a buffer big enough to hold any of the hostnames plus a
 297          * terminating char and also a buffer big enough to hold the hostname
 298          * plus a colon plus the path.
 299          */
 300         len = 0;
 301         for (s = 0; s < location->nservers; s++) {
 302                 const struct nfs4_string *buf = &location->servers[s];
 303                 if (buf->len > len)
 304                         len = buf->len;
 305         }
 306
 307         kfree(ctx->nfs_server.hostname);
 308         ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL);
 309         if (!ctx->nfs_server.hostname)
 310                 return -ENOMEM;
 311
 312         export_path = nfs4_pathname_string(&location->rootpath,
 313                                            &ctx->nfs_server.export_path_len);
 314         if (IS_ERR(export_path))
 315                 return PTR_ERR(export_path);
 316
 317         kfree(ctx->nfs_server.export_path);
 318         ctx->nfs_server.export_path = export_path;
 319
 320         source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
 321                          GFP_KERNEL);
 322         if (!source)
 323                 return -ENOMEM;
 324
 325         kfree(fc->source);
 326         fc->source = source;
 327         for (s = 0; s < location->nservers; s++) {
 328                 const struct nfs4_string *buf = &location->servers[s];
 329
 330                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 331                         continue;
 332
 333                 ctx->nfs_server.addrlen =
 334                         nfs_parse_server_name(buf->data, buf->len,
 335                                               &ctx->nfs_server._address,
 336                                               sizeof(ctx->nfs_server._address),
 337                                               fc->net_ns, 0);
 338                 if (ctx->nfs_server.addrlen == 0)
 339                         continue;
 340
 341                 rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
 342
 343                 memcpy(ctx->nfs_server.hostname, buf->data, buf->len);
 344                 ctx->nfs_server.hostname[buf->len] = '\0';
 345
 346                 p = source;
 347                 memcpy(p, buf->data, buf->len);
 348                 p += buf->len;
 349                 *p++ = ':';
 350                 memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len);
 351                 p += ctx->nfs_server.export_path_len;
 352                 *p = 0;
 353
 354                 ret = nfs4_get_referral_tree(fc);
 355                 if (ret == 0)
 356                         return 0;
 357         }
 358
 359         return ret;
 360 }
 361
 362 /**
 363  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 364  * @fc: pointer to struct nfs_fs_context
 365  * @locations: array of NFSv4 server location information
 366  *
 367  */
 368 static int nfs_follow_referral(struct fs_context *fc,
 369                                const struct nfs4_fs_locations *locations)
 370 {
 371         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 372         int loc, error;
 373
 374         if (locations == NULL || locations->nlocations <= 0)
 375                 return -ENOENT;
 376
 377         dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry);
 378
 379         /* Ensure fs path is a prefix of current dentry path */
 380         error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx);
 381         if (error < 0)
 382                 return error;
 383
 384         error = -ENOENT;
 385         for (loc = 0; loc < locations->nlocations; loc++) {
 386                 const struct nfs4_fs_location *location = &locations->locations[loc];
 387
 388                 if (location == NULL || location->nservers <= 0 ||
 389                     location->rootpath.ncomponents == 0)
 390                         continue;
 391
 392                 error = try_location(fc, location);
 393                 if (error == 0)
 394                         return 0;
 395         }
 396
 397         return error;
 398 }
 399
 400 /*
 401  * nfs_do_refmount - handle crossing a referral on server
 402  * @dentry - dentry of referral
 403  *
 404  */
 405 static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client)
 406 {
 407         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 408         struct dentry *dentry, *parent;
 409         struct nfs4_fs_locations *fs_locations = NULL;
 410         struct page *page;
 411         int err = -ENOMEM;
 412
 413         /* BUG_ON(IS_ROOT(dentry)); */
 414         page = alloc_page(GFP_KERNEL);
 415         if (!page)
 416                 return -ENOMEM;
 417
 418         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 419         if (!fs_locations)
 420                 goto out_free;
 421         fs_locations->fattr = nfs_alloc_fattr();
 422         if (!fs_locations->fattr)
 423                 goto out_free_2;
 424
 425         /* Get locations */
 426         dentry = ctx->clone_data.dentry;
 427         parent = dget_parent(dentry);
 428         dprintk("%s: getting locations for %pd2\n",
 429                 __func__, dentry);
 430
 431         err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
 432         dput(parent);
 433         if (err != 0)
 434                 goto out_free_3;
 435
 436         err = -ENOENT;
 437         if (fs_locations->nlocations <= 0 ||
 438             fs_locations->fs_path.ncomponents <= 0)
 439                 goto out_free_3;
 440
 441         err = nfs_follow_referral(fc, fs_locations);
 442 out_free_3:
 443         kfree(fs_locations->fattr);
 444 out_free_2:
 445         kfree(fs_locations);
 446 out_free:
 447         __free_page(page);
 448         return err;
 449 }
 450
 451 int nfs4_submount(struct fs_context *fc, struct nfs_server *server)
 452 {
 453         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 454         struct dentry *dentry = ctx->clone_data.dentry;
 455         struct dentry *parent = dget_parent(dentry);
 456         struct inode *dir = d_inode(parent);
 457         struct rpc_clnt *client;
 458         int ret;
 459
 460         /* Look it up again to get its attributes and sec flavor */
 461         client = nfs4_proc_lookup_mountpoint(dir, dentry, ctx->mntfh,
 462                                              ctx->clone_data.fattr);
 463         dput(parent);
 464         if (IS_ERR(client))
 465                 return PTR_ERR(client);
 466
 467         ctx->selected_flavor = client->cl_auth->au_flavor;
 468         if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 469                 ret = nfs_do_refmount(fc, client);
 470         } else {
 471                 ret = nfs_do_submount(fc);
 472         }
 473
 474         rpc_shutdown_client(client);
 475         return ret;
 476 }
 477
 478 /*
 479  * Try one location from the fs_locations array.
 480  *
 481  * Returns zero on success, or a negative errno value.
 482  */
 483 static int nfs4_try_replacing_one_location(struct nfs_server *server,
 484                 char *page, char *page2,
 485                 const struct nfs4_fs_location *location)
 486 {
 487         struct net *net = rpc_net_ns(server->client);
 488         struct sockaddr_storage *sap;
 489         unsigned int s;
 490         size_t salen;
 491         int error;
 492
 493         sap = kmalloc(sizeof(*sap), GFP_KERNEL);
 494         if (sap == NULL)
 495                 return -ENOMEM;
 496
 497         error = -ENOENT;
 498         for (s = 0; s < location->nservers; s++) {
 499                 const struct nfs4_string *buf = &location->servers[s];
 500                 char *hostname;
 501
 502                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
 503                         continue;
 504
 505                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
 506                         continue;
 507
 508                 salen = nfs_parse_server_name(buf->data, buf->len,
 509                                               sap, sizeof(*sap), net, 0);
 510                 if (salen == 0)
 511                         continue;
 512                 rpc_set_port((struct sockaddr *)sap, NFS_PORT);
 513
 514                 error = -ENOMEM;
 515                 hostname = kmemdup_nul(buf->data, buf->len, GFP_KERNEL);
 516                 if (hostname == NULL)
 517                         break;
 518
 519                 error = nfs4_update_server(server, hostname, sap, salen, net);
 520                 kfree(hostname);
 521                 if (error == 0)
 522                         break;
 523         }
 524
 525         kfree(sap);
 526         return error;
 527 }
 528
 529 /**
 530  * nfs4_replace_transport - set up transport to destination server
 531  *
 532  * @server: export being migrated
 533  * @locations: fs_locations array
 534  *
 535  * Returns zero on success, or a negative errno value.
 536  *
 537  * The client tries all the entries in the "locations" array, in the
 538  * order returned by the server, until one works or the end of the
 539  * array is reached.
 540  */
 541 int nfs4_replace_transport(struct nfs_server *server,
 542                            const struct nfs4_fs_locations *locations)
 543 {
 544         char *page = NULL, *page2 = NULL;
 545         int loc, error;
 546
 547         error = -ENOENT;
 548         if (locations == NULL || locations->nlocations <= 0)
 549                 goto out;
 550
 551         error = -ENOMEM;
 552         page = (char *) __get_free_page(GFP_USER);
 553         if (!page)
 554                 goto out;
 555         page2 = (char *) __get_free_page(GFP_USER);
 556         if (!page2)
 557                 goto out;
 558
 559         for (loc = 0; loc < locations->nlocations; loc++) {
 560                 const struct nfs4_fs_location *location =
 561                                                 &locations->locations[loc];
 562
 563                 if (location == NULL || location->nservers <= 0 ||
 564                     location->rootpath.ncomponents == 0)
 565                         continue;
 566
 567                 error = nfs4_try_replacing_one_location(server, page,
 568                                                         page2, location);
 569                 if (error == 0)
 570                         break;
 571         }
 572
 573 out:
 574         free_page((unsigned long)page);
 575         free_page((unsigned long)page2);
 576         return error;
 577 }