fs/nfs/nfs4namespace.c

   1 /*
   2  * linux/fs/nfs/nfs4namespace.c
   3  *
   4  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
   5  * - Modified by David Howells <dhowells@redhat.com>
   6  *
   7  * NFSv4 namespace
   8  */
   9
  10 #include <linux/dcache.h>
  11 #include <linux/mount.h>
  12 #include <linux/namei.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/nfs_mount.h>
  15 #include <linux/slab.h>
  16 #include <linux/string.h>
  17 #include <linux/sunrpc/clnt.h>
  18 #include <linux/sunrpc/addr.h>
  19 #include <linux/vfs.h>
  20 #include <linux/inet.h>
  21 #include "internal.h"
  22 #include "nfs4_fs.h"
  23 #include "dns_resolve.h"
  24
  25 #define NFSDBG_FACILITY         NFSDBG_VFS
  26
  27 /*
  28  * Convert the NFSv4 pathname components into a standard posix path.
  29  *
  30  * Note that the resulting string will be placed at the end of the buffer
  31  */
  32 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  33                                          char *buffer, ssize_t buflen)
  34 {
  35         char *end = buffer + buflen;
  36         int n;
  37
  38         *--end = '\0';
  39         buflen--;
  40
  41         n = pathname->ncomponents;
  42         while (--n >= 0) {
  43                 const struct nfs4_string *component = &pathname->components[n];
  44                 buflen -= component->len + 1;
  45                 if (buflen < 0)
  46                         goto Elong;
  47                 end -= component->len;
  48                 memcpy(end, component->data, component->len);
  49                 *--end = '/';
  50         }
  51         return end;
  52 Elong:
  53         return ERR_PTR(-ENAMETOOLONG);
  54 }
  55
  56 /*
  57  * return the path component of "<server>:<path>"
  58  *  nfspath - the "<server>:<path>" string
  59  *  end - one past the last char that could contain "<server>:"
  60  * returns NULL on failure
  61  */
  62 static char *nfs_path_component(const char *nfspath, const char *end)
  63 {
  64         char *p;
  65
  66         if (*nfspath == '[') {
  67                 /* parse [] escaped IPv6 addrs */
  68                 p = strchr(nfspath, ']');
  69                 if (p != NULL && ++p < end && *p == ':')
  70                         return p + 1;
  71         } else {
  72                 /* otherwise split on first colon */
  73                 p = strchr(nfspath, ':');
  74                 if (p != NULL && p < end)
  75                         return p + 1;
  76         }
  77         return NULL;
  78 }
  79
  80 /*
  81  * Determine the mount path as a string
  82  */
  83 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  84 {
  85         char *limit;
  86         char *path = nfs_path(&limit, dentry, buffer, buflen,
  87                               NFS_PATH_CANONICAL);
  88         if (!IS_ERR(path)) {
  89                 char *path_component = nfs_path_component(path, limit);
  90                 if (path_component)
  91                         return path_component;
  92         }
  93         return path;
  94 }
  95
  96 /*
  97  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  98  * believe to be the server path to this dentry
  99  */
 100 static int nfs4_validate_fspath(struct dentry *dentry,
 101                                 const struct nfs4_fs_locations *locations,
 102                                 char *page, char *page2)
 103 {
 104         const char *path, *fs_path;
 105
 106         path = nfs4_path(dentry, page, PAGE_SIZE);
 107         if (IS_ERR(path))
 108                 return PTR_ERR(path);
 109
 110         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
 111         if (IS_ERR(fs_path))
 112                 return PTR_ERR(fs_path);
 113
 114         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
 115                 dprintk("%s: path %s does not begin with fsroot %s\n",
 116                         __func__, path, fs_path);
 117                 return -ENOENT;
 118         }
 119
 120         return 0;
 121 }
 122
 123 static size_t nfs_parse_server_name(char *string, size_t len,
 124                 struct sockaddr *sa, size_t salen, struct nfs_server *server)
 125 {
 126         struct net *net = rpc_net_ns(server->client);
 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 the pseudoflavor of the first security mechanism in
 144  * "flavors" that is locally supported.  Return RPC_AUTH_UNIX if
 145  * no matching flavor is found in the array.  The "flavors" array
 146  * is searched in the order returned from the server, per RFC 3530
 147  * recommendation.
 148  */
 149 static rpc_authflavor_t nfs_find_best_sec(struct nfs_server *server,
 150                                           struct nfs4_secinfo_flavors *flavors)
 151 {
 152         rpc_authflavor_t pseudoflavor;
 153         struct nfs4_secinfo4 *secinfo;
 154         unsigned int i;
 155
 156         for (i = 0; i < flavors->num_flavors; i++) {
 157                 secinfo = &flavors->flavors[i];
 158
 159                 switch (secinfo->flavor) {
 160                 case RPC_AUTH_NULL:
 161                 case RPC_AUTH_UNIX:
 162                 case RPC_AUTH_GSS:
 163                         pseudoflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
 164                                                         &secinfo->flavor_info);
 165                         /* make sure pseudoflavor matches sec= mount opt */
 166                         if (pseudoflavor != RPC_AUTH_MAXFLAVOR &&
 167                             nfs_auth_info_match(&server->auth_info,
 168                                                 pseudoflavor))
 169                                 return pseudoflavor;
 170                         break;
 171                 }
 172         }
 173
 174         /* if there were any sec= options then nothing matched */
 175         if (server->auth_info.flavor_len > 0)
 176                 return -EPERM;
 177
 178         return RPC_AUTH_UNIX;
 179 }
 180
 181 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
 182 {
 183         struct page *page;
 184         struct nfs4_secinfo_flavors *flavors;
 185         rpc_authflavor_t flavor;
 186         int err;
 187
 188         page = alloc_page(GFP_KERNEL);
 189         if (!page)
 190                 return -ENOMEM;
 191         flavors = page_address(page);
 192
 193         err = nfs4_proc_secinfo(inode, name, flavors);
 194         if (err < 0) {
 195                 flavor = err;
 196                 goto out;
 197         }
 198
 199         flavor = nfs_find_best_sec(NFS_SERVER(inode), flavors);
 200
 201 out:
 202         put_page(page);
 203         return flavor;
 204 }
 205
 206 /*
 207  * Please call rpc_shutdown_client() when you are done with this client.
 208  */
 209 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 210                                         struct qstr *name)
 211 {
 212         rpc_authflavor_t flavor;
 213
 214         flavor = nfs4_negotiate_security(inode, name);
 215         if ((int)flavor < 0)
 216                 return ERR_PTR((int)flavor);
 217
 218         return rpc_clone_client_set_auth(clnt, flavor);
 219 }
 220
 221 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 222                                      char *page, char *page2,
 223                                      const struct nfs4_fs_location *location)
 224 {
 225         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 226         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 227         char *mnt_path;
 228         unsigned int maxbuflen;
 229         unsigned int s;
 230
 231         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 232         if (IS_ERR(mnt_path))
 233                 return ERR_CAST(mnt_path);
 234         mountdata->mnt_path = mnt_path;
 235         maxbuflen = mnt_path - 1 - page2;
 236
 237         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 238         if (mountdata->addr == NULL)
 239                 return ERR_PTR(-ENOMEM);
 240
 241         for (s = 0; s < location->nservers; s++) {
 242                 const struct nfs4_string *buf = &location->servers[s];
 243
 244                 if (buf->len <= 0 || buf->len >= maxbuflen)
 245                         continue;
 246
 247                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 248                         continue;
 249
 250                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 251                                 mountdata->addr, addr_bufsize,
 252                                 NFS_SB(mountdata->sb));
 253                 if (mountdata->addrlen == 0)
 254                         continue;
 255
 256                 rpc_set_port(mountdata->addr, NFS_PORT);
 257
 258                 memcpy(page2, buf->data, buf->len);
 259                 page2[buf->len] = '\0';
 260                 mountdata->hostname = page2;
 261
 262                 snprintf(page, PAGE_SIZE, "%s:%s",
 263                                 mountdata->hostname,
 264                                 mountdata->mnt_path);
 265
 266                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 267                 if (!IS_ERR(mnt))
 268                         break;
 269         }
 270         kfree(mountdata->addr);
 271         return mnt;
 272 }
 273
 274 /**
 275  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 276  * @dentry - parent directory
 277  * @locations - array of NFSv4 server location information
 278  *
 279  */
 280 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 281                                             const struct nfs4_fs_locations *locations)
 282 {
 283         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 284         struct nfs_clone_mount mountdata = {
 285                 .sb = dentry->d_sb,
 286                 .dentry = dentry,
 287                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 288         };
 289         char *page = NULL, *page2 = NULL;
 290         int loc, error;
 291
 292         if (locations == NULL || locations->nlocations <= 0)
 293                 goto out;
 294
 295         dprintk("%s: referral at %pd2\n", __func__, dentry);
 296
 297         page = (char *) __get_free_page(GFP_USER);
 298         if (!page)
 299                 goto out;
 300
 301         page2 = (char *) __get_free_page(GFP_USER);
 302         if (!page2)
 303                 goto out;
 304
 305         /* Ensure fs path is a prefix of current dentry path */
 306         error = nfs4_validate_fspath(dentry, locations, page, page2);
 307         if (error < 0) {
 308                 mnt = ERR_PTR(error);
 309                 goto out;
 310         }
 311
 312         for (loc = 0; loc < locations->nlocations; loc++) {
 313                 const struct nfs4_fs_location *location = &locations->locations[loc];
 314
 315                 if (location == NULL || location->nservers <= 0 ||
 316                     location->rootpath.ncomponents == 0)
 317                         continue;
 318
 319                 mnt = try_location(&mountdata, page, page2, location);
 320                 if (!IS_ERR(mnt))
 321                         break;
 322         }
 323
 324 out:
 325         free_page((unsigned long) page);
 326         free_page((unsigned long) page2);
 327         dprintk("%s: done\n", __func__);
 328         return mnt;
 329 }
 330
 331 /*
 332  * nfs_do_refmount - handle crossing a referral on server
 333  * @dentry - dentry of referral
 334  *
 335  */
 336 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 337 {
 338         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 339         struct dentry *parent;
 340         struct nfs4_fs_locations *fs_locations = NULL;
 341         struct page *page;
 342         int err;
 343
 344         /* BUG_ON(IS_ROOT(dentry)); */
 345         dprintk("%s: enter\n", __func__);
 346
 347         page = alloc_page(GFP_KERNEL);
 348         if (page == NULL)
 349                 goto out;
 350
 351         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 352         if (fs_locations == NULL)
 353                 goto out_free;
 354
 355         /* Get locations */
 356         mnt = ERR_PTR(-ENOENT);
 357
 358         parent = dget_parent(dentry);
 359         dprintk("%s: getting locations for %pd2\n",
 360                 __func__, dentry);
 361
 362         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 363         dput(parent);
 364         if (err != 0 ||
 365             fs_locations->nlocations <= 0 ||
 366             fs_locations->fs_path.ncomponents <= 0)
 367                 goto out_free;
 368
 369         mnt = nfs_follow_referral(dentry, fs_locations);
 370 out_free:
 371         __free_page(page);
 372         kfree(fs_locations);
 373 out:
 374         dprintk("%s: done\n", __func__);
 375         return mnt;
 376 }
 377
 378 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 379                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 380 {
 381         rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
 382         struct dentry *parent = dget_parent(dentry);
 383         struct inode *dir = parent->d_inode;
 384         struct qstr *name = &dentry->d_name;
 385         struct rpc_clnt *client;
 386         struct vfsmount *mnt;
 387
 388         /* Look it up again to get its attributes and sec flavor */
 389         client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
 390         dput(parent);
 391         if (IS_ERR(client))
 392                 return ERR_CAST(client);
 393
 394         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 395                 mnt = nfs_do_refmount(client, dentry);
 396                 goto out;
 397         }
 398
 399         if (client->cl_auth->au_flavor != flavor)
 400                 flavor = client->cl_auth->au_flavor;
 401         else {
 402                 rpc_authflavor_t new = nfs4_negotiate_security(dir, name);
 403                 if ((int)new >= 0)
 404                         flavor = new;
 405         }
 406         mnt = nfs_do_submount(dentry, fh, fattr, flavor);
 407 out:
 408         rpc_shutdown_client(client);
 409         return mnt;
 410 }
 411
 412 /*
 413  * Try one location from the fs_locations array.
 414  *
 415  * Returns zero on success, or a negative errno value.
 416  */
 417 static int nfs4_try_replacing_one_location(struct nfs_server *server,
 418                 char *page, char *page2,
 419                 const struct nfs4_fs_location *location)
 420 {
 421         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 422         struct sockaddr *sap;
 423         unsigned int s;
 424         size_t salen;
 425         int error;
 426
 427         sap = kmalloc(addr_bufsize, GFP_KERNEL);
 428         if (sap == NULL)
 429                 return -ENOMEM;
 430
 431         error = -ENOENT;
 432         for (s = 0; s < location->nservers; s++) {
 433                 const struct nfs4_string *buf = &location->servers[s];
 434                 char *hostname;
 435
 436                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
 437                         continue;
 438
 439                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
 440                         continue;
 441
 442                 salen = nfs_parse_server_name(buf->data, buf->len,
 443                                                 sap, addr_bufsize, server);
 444                 if (salen == 0)
 445                         continue;
 446                 rpc_set_port(sap, NFS_PORT);
 447
 448                 error = -ENOMEM;
 449                 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
 450                 if (hostname == NULL)
 451                         break;
 452
 453                 error = nfs4_update_server(server, hostname, sap, salen);
 454                 kfree(hostname);
 455                 if (error == 0)
 456                         break;
 457         }
 458
 459         kfree(sap);
 460         return error;
 461 }
 462
 463 /**
 464  * nfs4_replace_transport - set up transport to destination server
 465  *
 466  * @server: export being migrated
 467  * @locations: fs_locations array
 468  *
 469  * Returns zero on success, or a negative errno value.
 470  *
 471  * The client tries all the entries in the "locations" array, in the
 472  * order returned by the server, until one works or the end of the
 473  * array is reached.
 474  */
 475 int nfs4_replace_transport(struct nfs_server *server,
 476                            const struct nfs4_fs_locations *locations)
 477 {
 478         char *page = NULL, *page2 = NULL;
 479         int loc, error;
 480
 481         error = -ENOENT;
 482         if (locations == NULL || locations->nlocations <= 0)
 483                 goto out;
 484
 485         error = -ENOMEM;
 486         page = (char *) __get_free_page(GFP_USER);
 487         if (!page)
 488                 goto out;
 489         page2 = (char *) __get_free_page(GFP_USER);
 490         if (!page2)
 491                 goto out;
 492
 493         for (loc = 0; loc < locations->nlocations; loc++) {
 494                 const struct nfs4_fs_location *location =
 495                                                 &locations->locations[loc];
 496
 497                 if (location == NULL || location->nservers <= 0 ||
 498                     location->rootpath.ncomponents == 0)
 499                         continue;
 500
 501                 error = nfs4_try_replacing_one_location(server, page,
 502                                                         page2, location);
 503                 if (error == 0)
 504                         break;
 505         }
 506
 507 out:
 508         free_page((unsigned long)page);
 509         free_page((unsigned long)page2);
 510         return error;
 511 }