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 %s/%s\n", __func__,
 296                 dentry->d_parent->d_name.name, dentry->d_name.name);
 297
 298         page = (char *) __get_free_page(GFP_USER);
 299         if (!page)
 300                 goto out;
 301
 302         page2 = (char *) __get_free_page(GFP_USER);
 303         if (!page2)
 304                 goto out;
 305
 306         /* Ensure fs path is a prefix of current dentry path */
 307         error = nfs4_validate_fspath(dentry, locations, page, page2);
 308         if (error < 0) {
 309                 mnt = ERR_PTR(error);
 310                 goto out;
 311         }
 312
 313         for (loc = 0; loc < locations->nlocations; loc++) {
 314                 const struct nfs4_fs_location *location = &locations->locations[loc];
 315
 316                 if (location == NULL || location->nservers <= 0 ||
 317                     location->rootpath.ncomponents == 0)
 318                         continue;
 319
 320                 mnt = try_location(&mountdata, page, page2, location);
 321                 if (!IS_ERR(mnt))
 322                         break;
 323         }
 324
 325 out:
 326         free_page((unsigned long) page);
 327         free_page((unsigned long) page2);
 328         dprintk("%s: done\n", __func__);
 329         return mnt;
 330 }
 331
 332 /*
 333  * nfs_do_refmount - handle crossing a referral on server
 334  * @dentry - dentry of referral
 335  *
 336  */
 337 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 338 {
 339         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 340         struct dentry *parent;
 341         struct nfs4_fs_locations *fs_locations = NULL;
 342         struct page *page;
 343         int err;
 344
 345         /* BUG_ON(IS_ROOT(dentry)); */
 346         dprintk("%s: enter\n", __func__);
 347
 348         page = alloc_page(GFP_KERNEL);
 349         if (page == NULL)
 350                 goto out;
 351
 352         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 353         if (fs_locations == NULL)
 354                 goto out_free;
 355
 356         /* Get locations */
 357         mnt = ERR_PTR(-ENOENT);
 358
 359         parent = dget_parent(dentry);
 360         dprintk("%s: getting locations for %s/%s\n",
 361                 __func__, parent->d_name.name, dentry->d_name.name);
 362
 363         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 364         dput(parent);
 365         if (err != 0 ||
 366             fs_locations->nlocations <= 0 ||
 367             fs_locations->fs_path.ncomponents <= 0)
 368                 goto out_free;
 369
 370         mnt = nfs_follow_referral(dentry, fs_locations);
 371 out_free:
 372         __free_page(page);
 373         kfree(fs_locations);
 374 out:
 375         dprintk("%s: done\n", __func__);
 376         return mnt;
 377 }
 378
 379 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 380                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 381 {
 382         rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
 383         struct dentry *parent = dget_parent(dentry);
 384         struct inode *dir = parent->d_inode;
 385         struct qstr *name = &dentry->d_name;
 386         struct rpc_clnt *client;
 387         struct vfsmount *mnt;
 388
 389         /* Look it up again to get its attributes and sec flavor */
 390         client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
 391         dput(parent);
 392         if (IS_ERR(client))
 393                 return ERR_CAST(client);
 394
 395         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 396                 mnt = nfs_do_refmount(client, dentry);
 397                 goto out;
 398         }
 399
 400         if (client->cl_auth->au_flavor != flavor)
 401                 flavor = client->cl_auth->au_flavor;
 402         else {
 403                 rpc_authflavor_t new = nfs4_negotiate_security(dir, name);
 404                 if ((int)new >= 0)
 405                         flavor = new;
 406         }
 407         mnt = nfs_do_submount(dentry, fh, fattr, flavor);
 408 out:
 409         rpc_shutdown_client(client);
 410         return mnt;
 411 }
 412
 413 /*
 414  * Try one location from the fs_locations array.
 415  *
 416  * Returns zero on success, or a negative errno value.
 417  */
 418 static int nfs4_try_replacing_one_location(struct nfs_server *server,
 419                 char *page, char *page2,
 420                 const struct nfs4_fs_location *location)
 421 {
 422         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 423         struct sockaddr *sap;
 424         unsigned int s;
 425         size_t salen;
 426         int error;
 427
 428         sap = kmalloc(addr_bufsize, GFP_KERNEL);
 429         if (sap == NULL)
 430                 return -ENOMEM;
 431
 432         error = -ENOENT;
 433         for (s = 0; s < location->nservers; s++) {
 434                 const struct nfs4_string *buf = &location->servers[s];
 435                 char *hostname;
 436
 437                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
 438                         continue;
 439
 440                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
 441                         continue;
 442
 443                 salen = nfs_parse_server_name(buf->data, buf->len,
 444                                                 sap, addr_bufsize, server);
 445                 if (salen == 0)
 446                         continue;
 447                 rpc_set_port(sap, NFS_PORT);
 448
 449                 error = -ENOMEM;
 450                 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
 451                 if (hostname == NULL)
 452                         break;
 453
 454                 error = nfs4_update_server(server, hostname, sap, salen);
 455                 kfree(hostname);
 456                 if (error == 0)
 457                         break;
 458         }
 459
 460         kfree(sap);
 461         return error;
 462 }
 463
 464 /**
 465  * nfs4_replace_transport - set up transport to destination server
 466  *
 467  * @server: export being migrated
 468  * @locations: fs_locations array
 469  *
 470  * Returns zero on success, or a negative errno value.
 471  *
 472  * The client tries all the entries in the "locations" array, in the
 473  * order returned by the server, until one works or the end of the
 474  * array is reached.
 475  */
 476 int nfs4_replace_transport(struct nfs_server *server,
 477                            const struct nfs4_fs_locations *locations)
 478 {
 479         char *page = NULL, *page2 = NULL;
 480         int loc, error;
 481
 482         error = -ENOENT;
 483         if (locations == NULL || locations->nlocations <= 0)
 484                 goto out;
 485
 486         error = -ENOMEM;
 487         page = (char *) __get_free_page(GFP_USER);
 488         if (!page)
 489                 goto out;
 490         page2 = (char *) __get_free_page(GFP_USER);
 491         if (!page2)
 492                 goto out;
 493
 494         for (loc = 0; loc < locations->nlocations; loc++) {
 495                 const struct nfs4_fs_location *location =
 496                                                 &locations->locations[loc];
 497
 498                 if (location == NULL || location->nservers <= 0 ||
 499                     location->rootpath.ncomponents == 0)
 500                         continue;
 501
 502                 error = nfs4_try_replacing_one_location(server, page,
 503                                                         page2, location);
 504                 if (error == 0)
 505                         break;
 506         }
 507
 508 out:
 509         free_page((unsigned long)page);
 510         free_page((unsigned long)page2);
 511         return error;
 512 }