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/dcache.h>
  12 #include <linux/mount.h>
  13 #include <linux/namei.h>
  14 #include <linux/nfs_fs.h>
  15 #include <linux/nfs_mount.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18 #include <linux/sunrpc/clnt.h>
  19 #include <linux/sunrpc/addr.h>
  20 #include <linux/vfs.h>
  21 #include <linux/inet.h>
  22 #include "internal.h"
  23 #include "nfs4_fs.h"
  24 #include "dns_resolve.h"
  25
  26 #define NFSDBG_FACILITY         NFSDBG_VFS
  27
  28 /*
  29  * Convert the NFSv4 pathname components into a standard posix path.
  30  *
  31  * Note that the resulting string will be placed at the end of the buffer
  32  */
  33 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  34                                          char *buffer, ssize_t buflen)
  35 {
  36         char *end = buffer + buflen;
  37         int n;
  38
  39         *--end = '\0';
  40         buflen--;
  41
  42         n = pathname->ncomponents;
  43         while (--n >= 0) {
  44                 const struct nfs4_string *component = &pathname->components[n];
  45                 buflen -= component->len + 1;
  46                 if (buflen < 0)
  47                         goto Elong;
  48                 end -= component->len;
  49                 memcpy(end, component->data, component->len);
  50                 *--end = '/';
  51         }
  52         return end;
  53 Elong:
  54         return ERR_PTR(-ENAMETOOLONG);
  55 }
  56
  57 /*
  58  * return the path component of "<server>:<path>"
  59  *  nfspath - the "<server>:<path>" string
  60  *  end - one past the last char that could contain "<server>:"
  61  * returns NULL on failure
  62  */
  63 static char *nfs_path_component(const char *nfspath, const char *end)
  64 {
  65         char *p;
  66
  67         if (*nfspath == '[') {
  68                 /* parse [] escaped IPv6 addrs */
  69                 p = strchr(nfspath, ']');
  70                 if (p != NULL && ++p < end && *p == ':')
  71                         return p + 1;
  72         } else {
  73                 /* otherwise split on first colon */
  74                 p = strchr(nfspath, ':');
  75                 if (p != NULL && p < end)
  76                         return p + 1;
  77         }
  78         return NULL;
  79 }
  80
  81 /*
  82  * Determine the mount path as a string
  83  */
  84 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  85 {
  86         char *limit;
  87         char *path = nfs_path(&limit, dentry, buffer, buflen,
  88                               NFS_PATH_CANONICAL);
  89         if (!IS_ERR(path)) {
  90                 char *path_component = nfs_path_component(path, limit);
  91                 if (path_component)
  92                         return path_component;
  93         }
  94         return path;
  95 }
  96
  97 /*
  98  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  99  * believe to be the server path to this dentry
 100  */
 101 static int nfs4_validate_fspath(struct dentry *dentry,
 102                                 const struct nfs4_fs_locations *locations,
 103                                 char *page, char *page2)
 104 {
 105         const char *path, *fs_path;
 106
 107         path = nfs4_path(dentry, page, PAGE_SIZE);
 108         if (IS_ERR(path))
 109                 return PTR_ERR(path);
 110
 111         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
 112         if (IS_ERR(fs_path))
 113                 return PTR_ERR(fs_path);
 114
 115         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
 116                 dprintk("%s: path %s does not begin with fsroot %s\n",
 117                         __func__, path, fs_path);
 118                 return -ENOENT;
 119         }
 120
 121         return 0;
 122 }
 123
 124 static size_t nfs_parse_server_name(char *string, size_t len,
 125                 struct sockaddr *sa, size_t salen, struct net *net)
 126 {
 127         ssize_t ret;
 128
 129         ret = rpc_pton(net, string, len, sa, salen);
 130         if (ret == 0) {
 131                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
 132                 if (ret < 0)
 133                         ret = 0;
 134         }
 135         return ret;
 136 }
 137
 138 /**
 139  * nfs_find_best_sec - Find a security mechanism supported locally
 140  * @server: NFS server struct
 141  * @flavors: List of security tuples returned by SECINFO procedure
 142  *
 143  * Return an rpc client that uses the first security mechanism in
 144  * "flavors" that is locally supported.  The "flavors" array
 145  * is searched in the order returned from the server, per RFC 3530
 146  * recommendation and each flavor is checked for membership in the
 147  * sec= mount option list if it exists.
 148  *
 149  * Return -EPERM if no matching flavor is found in the array.
 150  *
 151  * Please call rpc_shutdown_client() when you are done with this rpc client.
 152  *
 153  */
 154 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
 155                                           struct nfs_server *server,
 156                                           struct nfs4_secinfo_flavors *flavors)
 157 {
 158         rpc_authflavor_t pflavor;
 159         struct nfs4_secinfo4 *secinfo;
 160         unsigned int i;
 161
 162         for (i = 0; i < flavors->num_flavors; i++) {
 163                 secinfo = &flavors->flavors[i];
 164
 165                 switch (secinfo->flavor) {
 166                 case RPC_AUTH_NULL:
 167                 case RPC_AUTH_UNIX:
 168                 case RPC_AUTH_GSS:
 169                         pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
 170                                                         &secinfo->flavor_info);
 171                         /* does the pseudoflavor match a sec= mount opt? */
 172                         if (pflavor != RPC_AUTH_MAXFLAVOR &&
 173                             nfs_auth_info_match(&server->auth_info, pflavor)) {
 174                                 struct rpc_clnt *new;
 175                                 struct rpc_cred *cred;
 176
 177                                 /* Cloning creates an rpc_auth for the flavor */
 178                                 new = rpc_clone_client_set_auth(clnt, pflavor);
 179                                 if (IS_ERR(new))
 180                                         continue;
 181                                 /**
 182                                 * Check that the user actually can use the
 183                                 * flavor. This is mostly for RPC_AUTH_GSS
 184                                 * where cr_init obtains a gss context
 185                                 */
 186                                 cred = rpcauth_lookupcred(new->cl_auth, 0);
 187                                 if (IS_ERR(cred)) {
 188                                         rpc_shutdown_client(new);
 189                                         continue;
 190                                 }
 191                                 put_rpccred(cred);
 192                                 return new;
 193                         }
 194                 }
 195         }
 196         return ERR_PTR(-EPERM);
 197 }
 198
 199 /**
 200  * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
 201  * return an rpc_clnt that uses the best available security flavor with
 202  * respect to the secinfo flavor list and the sec= mount options.
 203  *
 204  * @clnt: RPC client to clone
 205  * @inode: directory inode
 206  * @name: lookup name
 207  *
 208  * Please call rpc_shutdown_client() when you are done with this rpc client.
 209  */
 210 struct rpc_clnt *
 211 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
 212                                         const struct qstr *name)
 213 {
 214         struct page *page;
 215         struct nfs4_secinfo_flavors *flavors;
 216         struct rpc_clnt *new;
 217         int err;
 218
 219         page = alloc_page(GFP_KERNEL);
 220         if (!page)
 221                 return ERR_PTR(-ENOMEM);
 222
 223         flavors = page_address(page);
 224
 225         err = nfs4_proc_secinfo(inode, name, flavors);
 226         if (err < 0) {
 227                 new = ERR_PTR(err);
 228                 goto out;
 229         }
 230
 231         new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
 232
 233 out:
 234         put_page(page);
 235         return new;
 236 }
 237
 238 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 239                                      char *page, char *page2,
 240                                      const struct nfs4_fs_location *location)
 241 {
 242         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 243         struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client);
 244         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 245         char *mnt_path;
 246         unsigned int maxbuflen;
 247         unsigned int s;
 248
 249         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 250         if (IS_ERR(mnt_path))
 251                 return ERR_CAST(mnt_path);
 252         mountdata->mnt_path = mnt_path;
 253         maxbuflen = mnt_path - 1 - page2;
 254
 255         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 256         if (mountdata->addr == NULL)
 257                 return ERR_PTR(-ENOMEM);
 258
 259         for (s = 0; s < location->nservers; s++) {
 260                 const struct nfs4_string *buf = &location->servers[s];
 261
 262                 if (buf->len <= 0 || buf->len >= maxbuflen)
 263                         continue;
 264
 265                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 266                         continue;
 267
 268                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 269                                 mountdata->addr, addr_bufsize, net);
 270                 if (mountdata->addrlen == 0)
 271                         continue;
 272
 273                 memcpy(page2, buf->data, buf->len);
 274                 page2[buf->len] = '\0';
 275                 mountdata->hostname = page2;
 276
 277                 snprintf(page, PAGE_SIZE, "%s:%s",
 278                                 mountdata->hostname,
 279                                 mountdata->mnt_path);
 280
 281                 mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata);
 282                 if (!IS_ERR(mnt))
 283                         break;
 284         }
 285         kfree(mountdata->addr);
 286         return mnt;
 287 }
 288
 289 /**
 290  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 291  * @dentry - parent directory
 292  * @locations - array of NFSv4 server location information
 293  *
 294  */
 295 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 296                                             const struct nfs4_fs_locations *locations)
 297 {
 298         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 299         struct nfs_clone_mount mountdata = {
 300                 .sb = dentry->d_sb,
 301                 .dentry = dentry,
 302                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 303         };
 304         char *page = NULL, *page2 = NULL;
 305         int loc, error;
 306
 307         if (locations == NULL || locations->nlocations <= 0)
 308                 goto out;
 309
 310         dprintk("%s: referral at %pd2\n", __func__, dentry);
 311
 312         page = (char *) __get_free_page(GFP_USER);
 313         if (!page)
 314                 goto out;
 315
 316         page2 = (char *) __get_free_page(GFP_USER);
 317         if (!page2)
 318                 goto out;
 319
 320         /* Ensure fs path is a prefix of current dentry path */
 321         error = nfs4_validate_fspath(dentry, locations, page, page2);
 322         if (error < 0) {
 323                 mnt = ERR_PTR(error);
 324                 goto out;
 325         }
 326
 327         for (loc = 0; loc < locations->nlocations; loc++) {
 328                 const struct nfs4_fs_location *location = &locations->locations[loc];
 329
 330                 if (location == NULL || location->nservers <= 0 ||
 331                     location->rootpath.ncomponents == 0)
 332                         continue;
 333
 334                 mnt = try_location(&mountdata, page, page2, location);
 335                 if (!IS_ERR(mnt))
 336                         break;
 337         }
 338
 339 out:
 340         free_page((unsigned long) page);
 341         free_page((unsigned long) page2);
 342         return mnt;
 343 }
 344
 345 /*
 346  * nfs_do_refmount - handle crossing a referral on server
 347  * @dentry - dentry of referral
 348  *
 349  */
 350 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 351 {
 352         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 353         struct dentry *parent;
 354         struct nfs4_fs_locations *fs_locations = NULL;
 355         struct page *page;
 356         int err;
 357
 358         /* BUG_ON(IS_ROOT(dentry)); */
 359         page = alloc_page(GFP_KERNEL);
 360         if (page == NULL)
 361                 return mnt;
 362
 363         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 364         if (fs_locations == NULL)
 365                 goto out_free;
 366
 367         /* Get locations */
 368         mnt = ERR_PTR(-ENOENT);
 369
 370         parent = dget_parent(dentry);
 371         dprintk("%s: getting locations for %pd2\n",
 372                 __func__, dentry);
 373
 374         err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
 375         dput(parent);
 376         if (err != 0 ||
 377             fs_locations->nlocations <= 0 ||
 378             fs_locations->fs_path.ncomponents <= 0)
 379                 goto out_free;
 380
 381         mnt = nfs_follow_referral(dentry, fs_locations);
 382 out_free:
 383         __free_page(page);
 384         kfree(fs_locations);
 385         return mnt;
 386 }
 387
 388 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 389                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 390 {
 391         rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
 392         struct dentry *parent = dget_parent(dentry);
 393         struct inode *dir = d_inode(parent);
 394         const struct qstr *name = &dentry->d_name;
 395         struct rpc_clnt *client;
 396         struct vfsmount *mnt;
 397
 398         /* Look it up again to get its attributes and sec flavor */
 399         client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
 400         dput(parent);
 401         if (IS_ERR(client))
 402                 return ERR_CAST(client);
 403
 404         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 405                 mnt = nfs_do_refmount(client, dentry);
 406                 goto out;
 407         }
 408
 409         if (client->cl_auth->au_flavor != flavor)
 410                 flavor = client->cl_auth->au_flavor;
 411         mnt = nfs_do_submount(dentry, fh, fattr, flavor);
 412 out:
 413         rpc_shutdown_client(client);
 414         return mnt;
 415 }
 416
 417 /*
 418  * Try one location from the fs_locations array.
 419  *
 420  * Returns zero on success, or a negative errno value.
 421  */
 422 static int nfs4_try_replacing_one_location(struct nfs_server *server,
 423                 char *page, char *page2,
 424                 const struct nfs4_fs_location *location)
 425 {
 426         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 427         struct net *net = rpc_net_ns(server->client);
 428         struct sockaddr *sap;
 429         unsigned int s;
 430         size_t salen;
 431         int error;
 432
 433         sap = kmalloc(addr_bufsize, GFP_KERNEL);
 434         if (sap == NULL)
 435                 return -ENOMEM;
 436
 437         error = -ENOENT;
 438         for (s = 0; s < location->nservers; s++) {
 439                 const struct nfs4_string *buf = &location->servers[s];
 440                 char *hostname;
 441
 442                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
 443                         continue;
 444
 445                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
 446                         continue;
 447
 448                 salen = nfs_parse_server_name(buf->data, buf->len,
 449                                                 sap, addr_bufsize, net);
 450                 if (salen == 0)
 451                         continue;
 452                 rpc_set_port(sap, NFS_PORT);
 453
 454                 error = -ENOMEM;
 455                 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
 456                 if (hostname == NULL)
 457                         break;
 458
 459                 error = nfs4_update_server(server, hostname, sap, salen, net);
 460                 kfree(hostname);
 461                 if (error == 0)
 462                         break;
 463         }
 464
 465         kfree(sap);
 466         return error;
 467 }
 468
 469 /**
 470  * nfs4_replace_transport - set up transport to destination server
 471  *
 472  * @server: export being migrated
 473  * @locations: fs_locations array
 474  *
 475  * Returns zero on success, or a negative errno value.
 476  *
 477  * The client tries all the entries in the "locations" array, in the
 478  * order returned by the server, until one works or the end of the
 479  * array is reached.
 480  */
 481 int nfs4_replace_transport(struct nfs_server *server,
 482                            const struct nfs4_fs_locations *locations)
 483 {
 484         char *page = NULL, *page2 = NULL;
 485         int loc, error;
 486
 487         error = -ENOENT;
 488         if (locations == NULL || locations->nlocations <= 0)
 489                 goto out;
 490
 491         error = -ENOMEM;
 492         page = (char *) __get_free_page(GFP_USER);
 493         if (!page)
 494                 goto out;
 495         page2 = (char *) __get_free_page(GFP_USER);
 496         if (!page2)
 497                 goto out;
 498
 499         for (loc = 0; loc < locations->nlocations; loc++) {
 500                 const struct nfs4_fs_location *location =
 501                                                 &locations->locations[loc];
 502
 503                 if (location == NULL || location->nservers <= 0 ||
 504                     location->rootpath.ncomponents == 0)
 505                         continue;
 506
 507                 error = nfs4_try_replacing_one_location(server, page,
 508                                                         page2, location);
 509                 if (error == 0)
 510                         break;
 511         }
 512
 513 out:
 514         free_page((unsigned long)page);
 515         free_page((unsigned long)page2);
 516         return error;
 517 }