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 static size_t nfs_parse_server_name(char *string, size_t len, 168 struct sockaddr *sa, size_t salen, struct net *net) 169 { 170 ssize_t ret; 171 172 ret = rpc_pton(net, string, len, sa, salen); 173 if (ret == 0) { 174 ret = nfs_dns_resolve_name(net, string, len, sa, salen); 175 if (ret < 0) 176 ret = 0; 177 } 178 return ret; 179 } 180 181 /** 182 * nfs_find_best_sec - Find a security mechanism supported locally 183 * @clnt: pointer to rpc_clnt 184 * @server: NFS server struct 185 * @flavors: List of security tuples returned by SECINFO procedure 186 * 187 * Return an rpc client that uses the first security mechanism in 188 * "flavors" that is locally supported. The "flavors" array 189 * is searched in the order returned from the server, per RFC 3530 190 * recommendation and each flavor is checked for membership in the 191 * sec= mount option list if it exists. 192 * 193 * Return -EPERM if no matching flavor is found in the array. 194 * 195 * Please call rpc_shutdown_client() when you are done with this rpc client. 196 * 197 */ 198 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt, 199 struct nfs_server *server, 200 struct nfs4_secinfo_flavors *flavors) 201 { 202 rpc_authflavor_t pflavor; 203 struct nfs4_secinfo4 *secinfo; 204 unsigned int i; 205 206 for (i = 0; i < flavors->num_flavors; i++) { 207 secinfo = &flavors->flavors[i]; 208 209 switch (secinfo->flavor) { 210 case RPC_AUTH_NULL: 211 case RPC_AUTH_UNIX: 212 case RPC_AUTH_GSS: 213 pflavor = rpcauth_get_pseudoflavor(secinfo->flavor, 214 &secinfo->flavor_info); 215 /* does the pseudoflavor match a sec= mount opt? */ 216 if (pflavor != RPC_AUTH_MAXFLAVOR && 217 nfs_auth_info_match(&server->auth_info, pflavor)) { 218 struct rpc_clnt *new; 219 struct rpc_cred *cred; 220 221 /* Cloning creates an rpc_auth for the flavor */ 222 new = rpc_clone_client_set_auth(clnt, pflavor); 223 if (IS_ERR(new)) 224 continue; 225 /** 226 * Check that the user actually can use the 227 * flavor. This is mostly for RPC_AUTH_GSS 228 * where cr_init obtains a gss context 229 */ 230 cred = rpcauth_lookupcred(new->cl_auth, 0); 231 if (IS_ERR(cred)) { 232 rpc_shutdown_client(new); 233 continue; 234 } 235 put_rpccred(cred); 236 return new; 237 } 238 } 239 } 240 return ERR_PTR(-EPERM); 241 } 242 243 /** 244 * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup, 245 * return an rpc_clnt that uses the best available security flavor with 246 * respect to the secinfo flavor list and the sec= mount options. 247 * 248 * @clnt: RPC client to clone 249 * @inode: directory inode 250 * @name: lookup name 251 * 252 * Please call rpc_shutdown_client() when you are done with this rpc client. 253 */ 254 struct rpc_clnt * 255 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode, 256 const struct qstr *name) 257 { 258 struct page *page; 259 struct nfs4_secinfo_flavors *flavors; 260 struct rpc_clnt *new; 261 int err; 262 263 page = alloc_page(GFP_KERNEL); 264 if (!page) 265 return ERR_PTR(-ENOMEM); 266 267 flavors = page_address(page); 268 269 err = nfs4_proc_secinfo(inode, name, flavors); 270 if (err < 0) { 271 new = ERR_PTR(err); 272 goto out; 273 } 274 275 new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors); 276 277 out: 278 put_page(page); 279 return new; 280 } 281 282 static int try_location(struct fs_context *fc, 283 const struct nfs4_fs_location *location) 284 { 285 struct nfs_fs_context *ctx = nfs_fc2context(fc); 286 unsigned int len, s; 287 char *export_path, *source, *p; 288 int ret = -ENOENT; 289 290 /* Allocate a buffer big enough to hold any of the hostnames plus a 291 * terminating char and also a buffer big enough to hold the hostname 292 * plus a colon plus the path. 293 */ 294 len = 0; 295 for (s = 0; s < location->nservers; s++) { 296 const struct nfs4_string *buf = &location->servers[s]; 297 if (buf->len > len) 298 len = buf->len; 299 } 300 301 kfree(ctx->nfs_server.hostname); 302 ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL); 303 if (!ctx->nfs_server.hostname) 304 return -ENOMEM; 305 306 export_path = nfs4_pathname_string(&location->rootpath, 307 &ctx->nfs_server.export_path_len); 308 if (IS_ERR(export_path)) 309 return PTR_ERR(export_path); 310 311 kfree(ctx->nfs_server.export_path); 312 ctx->nfs_server.export_path = export_path; 313 314 source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1, 315 GFP_KERNEL); 316 if (!source) 317 return -ENOMEM; 318 319 kfree(fc->source); 320 fc->source = source; 321 for (s = 0; s < location->nservers; s++) { 322 const struct nfs4_string *buf = &location->servers[s]; 323 324 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len)) 325 continue; 326 327 ctx->nfs_server.addrlen = 328 nfs_parse_server_name(buf->data, buf->len, 329 &ctx->nfs_server.address, 330 sizeof(ctx->nfs_server._address), 331 fc->net_ns); 332 if (ctx->nfs_server.addrlen == 0) 333 continue; 334 335 rpc_set_port(&ctx->nfs_server.address, NFS_PORT); 336 337 memcpy(ctx->nfs_server.hostname, buf->data, buf->len); 338 ctx->nfs_server.hostname[buf->len] = '\0'; 339 340 p = source; 341 memcpy(p, buf->data, buf->len); 342 p += buf->len; 343 *p++ = ':'; 344 memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len); 345 p += ctx->nfs_server.export_path_len; 346 *p = 0; 347 348 ret = nfs4_get_referral_tree(fc); 349 if (ret == 0) 350 return 0; 351 } 352 353 return ret; 354 } 355 356 /** 357 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error 358 * @fc: pointer to struct nfs_fs_context 359 * @locations: array of NFSv4 server location information 360 * 361 */ 362 static int nfs_follow_referral(struct fs_context *fc, 363 const struct nfs4_fs_locations *locations) 364 { 365 struct nfs_fs_context *ctx = nfs_fc2context(fc); 366 int loc, error; 367 368 if (locations == NULL || locations->nlocations <= 0) 369 return -ENOENT; 370 371 dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry); 372 373 /* Ensure fs path is a prefix of current dentry path */ 374 error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx); 375 if (error < 0) 376 return error; 377 378 error = -ENOENT; 379 for (loc = 0; loc < locations->nlocations; loc++) { 380 const struct nfs4_fs_location *location = &locations->locations[loc]; 381 382 if (location == NULL || location->nservers <= 0 || 383 location->rootpath.ncomponents == 0) 384 continue; 385 386 error = try_location(fc, location); 387 if (error == 0) 388 return 0; 389 } 390 391 return error; 392 } 393 394 /* 395 * nfs_do_refmount - handle crossing a referral on server 396 * @dentry - dentry of referral 397 * 398 */ 399 static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client) 400 { 401 struct nfs_fs_context *ctx = nfs_fc2context(fc); 402 struct dentry *dentry, *parent; 403 struct nfs4_fs_locations *fs_locations = NULL; 404 struct page *page; 405 int err = -ENOMEM; 406 407 /* BUG_ON(IS_ROOT(dentry)); */ 408 page = alloc_page(GFP_KERNEL); 409 if (!page) 410 return -ENOMEM; 411 412 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL); 413 if (!fs_locations) 414 goto out_free; 415 416 /* Get locations */ 417 dentry = ctx->clone_data.dentry; 418 parent = dget_parent(dentry); 419 dprintk("%s: getting locations for %pd2\n", 420 __func__, dentry); 421 422 err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page); 423 dput(parent); 424 if (err != 0) 425 goto out_free_2; 426 427 err = -ENOENT; 428 if (fs_locations->nlocations <= 0 || 429 fs_locations->fs_path.ncomponents <= 0) 430 goto out_free_2; 431 432 err = nfs_follow_referral(fc, fs_locations); 433 out_free_2: 434 kfree(fs_locations); 435 out_free: 436 __free_page(page); 437 return err; 438 } 439 440 int nfs4_submount(struct fs_context *fc, struct nfs_server *server) 441 { 442 struct nfs_fs_context *ctx = nfs_fc2context(fc); 443 struct dentry *dentry = ctx->clone_data.dentry; 444 struct dentry *parent = dget_parent(dentry); 445 struct inode *dir = d_inode(parent); 446 struct rpc_clnt *client; 447 int ret; 448 449 /* Look it up again to get its attributes and sec flavor */ 450 client = nfs4_proc_lookup_mountpoint(dir, dentry, ctx->mntfh, 451 ctx->clone_data.fattr); 452 dput(parent); 453 if (IS_ERR(client)) 454 return PTR_ERR(client); 455 456 ctx->selected_flavor = client->cl_auth->au_flavor; 457 if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 458 ret = nfs_do_refmount(fc, client); 459 } else { 460 ret = nfs_do_submount(fc); 461 } 462 463 rpc_shutdown_client(client); 464 return ret; 465 } 466 467 /* 468 * Try one location from the fs_locations array. 469 * 470 * Returns zero on success, or a negative errno value. 471 */ 472 static int nfs4_try_replacing_one_location(struct nfs_server *server, 473 char *page, char *page2, 474 const struct nfs4_fs_location *location) 475 { 476 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 477 struct net *net = rpc_net_ns(server->client); 478 struct sockaddr *sap; 479 unsigned int s; 480 size_t salen; 481 int error; 482 483 sap = kmalloc(addr_bufsize, GFP_KERNEL); 484 if (sap == NULL) 485 return -ENOMEM; 486 487 error = -ENOENT; 488 for (s = 0; s < location->nservers; s++) { 489 const struct nfs4_string *buf = &location->servers[s]; 490 char *hostname; 491 492 if (buf->len <= 0 || buf->len > PAGE_SIZE) 493 continue; 494 495 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL) 496 continue; 497 498 salen = nfs_parse_server_name(buf->data, buf->len, 499 sap, addr_bufsize, net); 500 if (salen == 0) 501 continue; 502 rpc_set_port(sap, NFS_PORT); 503 504 error = -ENOMEM; 505 hostname = kmemdup_nul(buf->data, buf->len, GFP_KERNEL); 506 if (hostname == NULL) 507 break; 508 509 error = nfs4_update_server(server, hostname, sap, salen, net); 510 kfree(hostname); 511 if (error == 0) 512 break; 513 } 514 515 kfree(sap); 516 return error; 517 } 518 519 /** 520 * nfs4_replace_transport - set up transport to destination server 521 * 522 * @server: export being migrated 523 * @locations: fs_locations array 524 * 525 * Returns zero on success, or a negative errno value. 526 * 527 * The client tries all the entries in the "locations" array, in the 528 * order returned by the server, until one works or the end of the 529 * array is reached. 530 */ 531 int nfs4_replace_transport(struct nfs_server *server, 532 const struct nfs4_fs_locations *locations) 533 { 534 char *page = NULL, *page2 = NULL; 535 int loc, error; 536 537 error = -ENOENT; 538 if (locations == NULL || locations->nlocations <= 0) 539 goto out; 540 541 error = -ENOMEM; 542 page = (char *) __get_free_page(GFP_USER); 543 if (!page) 544 goto out; 545 page2 = (char *) __get_free_page(GFP_USER); 546 if (!page2) 547 goto out; 548 549 for (loc = 0; loc < locations->nlocations; loc++) { 550 const struct nfs4_fs_location *location = 551 &locations->locations[loc]; 552 553 if (location == NULL || location->nservers <= 0 || 554 location->rootpath.ncomponents == 0) 555 continue; 556 557 error = nfs4_try_replacing_one_location(server, page, 558 page2, location); 559 if (error == 0) 560 break; 561 } 562 563 out: 564 free_page((unsigned long)page); 565 free_page((unsigned long)page2); 566 return error; 567 } 568