root/fs/nfs/nfs4namespace.c

DEFINITIONS

1. nfs4_pathname_string
2. nfs_path_component
3. nfs4_path
4. nfs4_validate_fspath
5. nfs_parse_server_name
6. nfs_find_best_sec
7. nfs4_negotiate_security
8. try_location
9. nfs_follow_referral
10. nfs_do_refmount
11. nfs4_submount
12. nfs4_try_replacing_one_location
13. nfs4_replace_transport

   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  * @clnt: pointer to rpc_clnt
 141  * @server: NFS server struct
 142  * @flavors: List of security tuples returned by SECINFO procedure
 143  *
 144  * Return an rpc client that uses the first security mechanism in
 145  * "flavors" that is locally supported.  The "flavors" array
 146  * is searched in the order returned from the server, per RFC 3530
 147  * recommendation and each flavor is checked for membership in the
 148  * sec= mount option list if it exists.
 149  *
 150  * Return -EPERM if no matching flavor is found in the array.
 151  *
 152  * Please call rpc_shutdown_client() when you are done with this rpc client.
 153  *
 154  */
 155 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
 156                                           struct nfs_server *server,
 157                                           struct nfs4_secinfo_flavors *flavors)
 158 {
 159         rpc_authflavor_t pflavor;
 160         struct nfs4_secinfo4 *secinfo;
 161         unsigned int i;
 162 
 163         for (i = 0; i < flavors->num_flavors; i++) {
 164                 secinfo = &flavors->flavors[i];
 165 
 166                 switch (secinfo->flavor) {
 167                 case RPC_AUTH_NULL:
 168                 case RPC_AUTH_UNIX:
 169                 case RPC_AUTH_GSS:
 170                         pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
 171                                                         &secinfo->flavor_info);
 172                         /* does the pseudoflavor match a sec= mount opt? */
 173                         if (pflavor != RPC_AUTH_MAXFLAVOR &&
 174                             nfs_auth_info_match(&server->auth_info, pflavor)) {
 175                                 struct rpc_clnt *new;
 176                                 struct rpc_cred *cred;
 177 
 178                                 /* Cloning creates an rpc_auth for the flavor */
 179                                 new = rpc_clone_client_set_auth(clnt, pflavor);
 180                                 if (IS_ERR(new))
 181                                         continue;
 182                                 /**
 183                                 * Check that the user actually can use the
 184                                 * flavor. This is mostly for RPC_AUTH_GSS
 185                                 * where cr_init obtains a gss context
 186                                 */
 187                                 cred = rpcauth_lookupcred(new->cl_auth, 0);
 188                                 if (IS_ERR(cred)) {
 189                                         rpc_shutdown_client(new);
 190                                         continue;
 191                                 }
 192                                 put_rpccred(cred);
 193                                 return new;
 194                         }
 195                 }
 196         }
 197         return ERR_PTR(-EPERM);
 198 }
 199 
 200 /**
 201  * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
 202  * return an rpc_clnt that uses the best available security flavor with
 203  * respect to the secinfo flavor list and the sec= mount options.
 204  *
 205  * @clnt: RPC client to clone
 206  * @inode: directory inode
 207  * @name: lookup name
 208  *
 209  * Please call rpc_shutdown_client() when you are done with this rpc client.
 210  */
 211 struct rpc_clnt *
 212 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
 213                                         const struct qstr *name)
 214 {
 215         struct page *page;
 216         struct nfs4_secinfo_flavors *flavors;
 217         struct rpc_clnt *new;
 218         int err;
 219 
 220         page = alloc_page(GFP_KERNEL);
 221         if (!page)
 222                 return ERR_PTR(-ENOMEM);
 223 
 224         flavors = page_address(page);
 225 
 226         err = nfs4_proc_secinfo(inode, name, flavors);
 227         if (err < 0) {
 228                 new = ERR_PTR(err);
 229                 goto out;
 230         }
 231 
 232         new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
 233 
 234 out:
 235         put_page(page);
 236         return new;
 237 }
 238 
 239 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 240                                      char *page, char *page2,
 241                                      const struct nfs4_fs_location *location)
 242 {
 243         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 244         struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client);
 245         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 246         char *mnt_path;
 247         unsigned int maxbuflen;
 248         unsigned int s;
 249 
 250         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 251         if (IS_ERR(mnt_path))
 252                 return ERR_CAST(mnt_path);
 253         mountdata->mnt_path = mnt_path;
 254         maxbuflen = mnt_path - 1 - page2;
 255 
 256         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 257         if (mountdata->addr == NULL)
 258                 return ERR_PTR(-ENOMEM);
 259 
 260         for (s = 0; s < location->nservers; s++) {
 261                 const struct nfs4_string *buf = &location->servers[s];
 262 
 263                 if (buf->len <= 0 || buf->len >= maxbuflen)
 264                         continue;
 265 
 266                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 267                         continue;
 268 
 269                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 270                                 mountdata->addr, addr_bufsize, net);
 271                 if (mountdata->addrlen == 0)
 272                         continue;
 273 
 274                 memcpy(page2, buf->data, buf->len);
 275                 page2[buf->len] = '\0';
 276                 mountdata->hostname = page2;
 277 
 278                 snprintf(page, PAGE_SIZE, "%s:%s",
 279                                 mountdata->hostname,
 280                                 mountdata->mnt_path);
 281 
 282                 mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata);
 283                 if (!IS_ERR(mnt))
 284                         break;
 285         }
 286         kfree(mountdata->addr);
 287         return mnt;
 288 }
 289 
 290 /**
 291  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 292  * @dentry: parent directory
 293  * @locations: array of NFSv4 server location information
 294  *
 295  */
 296 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 297                                             const struct nfs4_fs_locations *locations)
 298 {
 299         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 300         struct nfs_clone_mount mountdata = {
 301                 .sb = dentry->d_sb,
 302                 .dentry = dentry,
 303                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 304         };
 305         char *page = NULL, *page2 = NULL;
 306         int loc, error;
 307 
 308         if (locations == NULL || locations->nlocations <= 0)
 309                 goto out;
 310 
 311         dprintk("%s: referral at %pd2\n", __func__, dentry);
 312 
 313         page = (char *) __get_free_page(GFP_USER);
 314         if (!page)
 315                 goto out;
 316 
 317         page2 = (char *) __get_free_page(GFP_USER);
 318         if (!page2)
 319                 goto out;
 320 
 321         /* Ensure fs path is a prefix of current dentry path */
 322         error = nfs4_validate_fspath(dentry, locations, page, page2);
 323         if (error < 0) {
 324                 mnt = ERR_PTR(error);
 325                 goto out;
 326         }
 327 
 328         for (loc = 0; loc < locations->nlocations; loc++) {
 329                 const struct nfs4_fs_location *location = &locations->locations[loc];
 330 
 331                 if (location == NULL || location->nservers <= 0 ||
 332                     location->rootpath.ncomponents == 0)
 333                         continue;
 334 
 335                 mnt = try_location(&mountdata, page, page2, location);
 336                 if (!IS_ERR(mnt))
 337                         break;
 338         }
 339 
 340 out:
 341         free_page((unsigned long) page);
 342         free_page((unsigned long) page2);
 343         return mnt;
 344 }
 345 
 346 /*
 347  * nfs_do_refmount - handle crossing a referral on server
 348  * @dentry - dentry of referral
 349  *
 350  */
 351 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 352 {
 353         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 354         struct dentry *parent;
 355         struct nfs4_fs_locations *fs_locations = NULL;
 356         struct page *page;
 357         int err;
 358 
 359         /* BUG_ON(IS_ROOT(dentry)); */
 360         page = alloc_page(GFP_KERNEL);
 361         if (page == NULL)
 362                 return mnt;
 363 
 364         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 365         if (fs_locations == NULL)
 366                 goto out_free;
 367 
 368         /* Get locations */
 369         mnt = ERR_PTR(-ENOENT);
 370 
 371         parent = dget_parent(dentry);
 372         dprintk("%s: getting locations for %pd2\n",
 373                 __func__, dentry);
 374 
 375         err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
 376         dput(parent);
 377         if (err != 0 ||
 378             fs_locations->nlocations <= 0 ||
 379             fs_locations->fs_path.ncomponents <= 0)
 380                 goto out_free;
 381 
 382         mnt = nfs_follow_referral(dentry, fs_locations);
 383 out_free:
 384         __free_page(page);
 385         kfree(fs_locations);
 386         return mnt;
 387 }
 388 
 389 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 390                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 391 {
 392         rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
 393         struct dentry *parent = dget_parent(dentry);
 394         struct inode *dir = d_inode(parent);
 395         const struct qstr *name = &dentry->d_name;
 396         struct rpc_clnt *client;
 397         struct vfsmount *mnt;
 398 
 399         /* Look it up again to get its attributes and sec flavor */
 400         client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
 401         dput(parent);
 402         if (IS_ERR(client))
 403                 return ERR_CAST(client);
 404 
 405         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 406                 mnt = nfs_do_refmount(client, dentry);
 407                 goto out;
 408         }
 409 
 410         if (client->cl_auth->au_flavor != flavor)
 411                 flavor = client->cl_auth->au_flavor;
 412         mnt = nfs_do_submount(dentry, fh, fattr, flavor);
 413 out:
 414         rpc_shutdown_client(client);
 415         return mnt;
 416 }
 417 
 418 /*
 419  * Try one location from the fs_locations array.
 420  *
 421  * Returns zero on success, or a negative errno value.
 422  */
 423 static int nfs4_try_replacing_one_location(struct nfs_server *server,
 424                 char *page, char *page2,
 425                 const struct nfs4_fs_location *location)
 426 {
 427         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 428         struct net *net = rpc_net_ns(server->client);
 429         struct sockaddr *sap;
 430         unsigned int s;
 431         size_t salen;
 432         int error;
 433 
 434         sap = kmalloc(addr_bufsize, GFP_KERNEL);
 435         if (sap == NULL)
 436                 return -ENOMEM;
 437 
 438         error = -ENOENT;
 439         for (s = 0; s < location->nservers; s++) {
 440                 const struct nfs4_string *buf = &location->servers[s];
 441                 char *hostname;
 442 
 443                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
 444                         continue;
 445 
 446                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
 447                         continue;
 448 
 449                 salen = nfs_parse_server_name(buf->data, buf->len,
 450                                                 sap, addr_bufsize, net);
 451                 if (salen == 0)
 452                         continue;
 453                 rpc_set_port(sap, NFS_PORT);
 454 
 455                 error = -ENOMEM;
 456                 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
 457                 if (hostname == NULL)
 458                         break;
 459 
 460                 error = nfs4_update_server(server, hostname, sap, salen, net);
 461                 kfree(hostname);
 462                 if (error == 0)
 463                         break;
 464         }
 465 
 466         kfree(sap);
 467         return error;
 468 }
 469 
 470 /**
 471  * nfs4_replace_transport - set up transport to destination server
 472  *
 473  * @server: export being migrated
 474  * @locations: fs_locations array
 475  *
 476  * Returns zero on success, or a negative errno value.
 477  *
 478  * The client tries all the entries in the "locations" array, in the
 479  * order returned by the server, until one works or the end of the
 480  * array is reached.
 481  */
 482 int nfs4_replace_transport(struct nfs_server *server,
 483                            const struct nfs4_fs_locations *locations)
 484 {
 485         char *page = NULL, *page2 = NULL;
 486         int loc, error;
 487 
 488         error = -ENOENT;
 489         if (locations == NULL || locations->nlocations <= 0)
 490                 goto out;
 491 
 492         error = -ENOMEM;
 493         page = (char *) __get_free_page(GFP_USER);
 494         if (!page)
 495                 goto out;
 496         page2 = (char *) __get_free_page(GFP_USER);
 497         if (!page2)
 498                 goto out;
 499 
 500         for (loc = 0; loc < locations->nlocations; loc++) {
 501                 const struct nfs4_fs_location *location =
 502                                                 &locations->locations[loc];
 503 
 504                 if (location == NULL || location->nservers <= 0 ||
 505                     location->rootpath.ncomponents == 0)
 506                         continue;
 507 
 508                 error = nfs4_try_replacing_one_location(server, page,
 509                                                         page2, location);
 510                 if (error == 0)
 511                         break;
 512         }
 513 
 514 out:
 515         free_page((unsigned long)page);
 516         free_page((unsigned long)page2);
 517         return error;
 518 }