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 } 578