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, *fs_path; 134 char *buf; 135 unsigned short len; 136 int n; 137 138 buf = kmalloc(4096, GFP_KERNEL); 139 path = nfs4_path(dentry, buf, 4096); 140 if (IS_ERR(path)) { 141 kfree(buf); 142 return PTR_ERR(path); 143 } 144 145 fs_path = nfs4_pathname_string(&locations->fs_path, &len); 146 if (IS_ERR(fs_path)) { 147 kfree(buf); 148 return PTR_ERR(fs_path); 149 } 150 151 n = strncmp(path, fs_path, len); 152 kfree(buf); 153 kfree(fs_path); 154 if (n != 0) { 155 dprintk("%s: path %s does not begin with fsroot %s\n", 156 __func__, path, ctx->nfs_server.export_path); 157 return -ENOENT; 158 } 159 160 return 0; 161 } 162 163 static size_t nfs_parse_server_name(char *string, size_t len, 164 struct sockaddr *sa, size_t salen, struct net *net) 165 { 166 ssize_t ret; 167 168 ret = rpc_pton(net, string, len, sa, salen); 169 if (ret == 0) { 170 ret = nfs_dns_resolve_name(net, string, len, sa, salen); 171 if (ret < 0) 172 ret = 0; 173 } 174 return ret; 175 } 176 177 /** 178 * nfs_find_best_sec - Find a security mechanism supported locally 179 * @clnt: pointer to rpc_clnt 180 * @server: NFS server struct 181 * @flavors: List of security tuples returned by SECINFO procedure 182 * 183 * Return an rpc client that uses the first security mechanism in 184 * "flavors" that is locally supported. The "flavors" array 185 * is searched in the order returned from the server, per RFC 3530 186 * recommendation and each flavor is checked for membership in the 187 * sec= mount option list if it exists. 188 * 189 * Return -EPERM if no matching flavor is found in the array. 190 * 191 * Please call rpc_shutdown_client() when you are done with this rpc client. 192 * 193 */ 194 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt, 195 struct nfs_server *server, 196 struct nfs4_secinfo_flavors *flavors) 197 { 198 rpc_authflavor_t pflavor; 199 struct nfs4_secinfo4 *secinfo; 200 unsigned int i; 201 202 for (i = 0; i < flavors->num_flavors; i++) { 203 secinfo = &flavors->flavors[i]; 204 205 switch (secinfo->flavor) { 206 case RPC_AUTH_NULL: 207 case RPC_AUTH_UNIX: 208 case RPC_AUTH_GSS: 209 pflavor = rpcauth_get_pseudoflavor(secinfo->flavor, 210 &secinfo->flavor_info); 211 /* does the pseudoflavor match a sec= mount opt? */ 212 if (pflavor != RPC_AUTH_MAXFLAVOR && 213 nfs_auth_info_match(&server->auth_info, pflavor)) { 214 struct rpc_clnt *new; 215 struct rpc_cred *cred; 216 217 /* Cloning creates an rpc_auth for the flavor */ 218 new = rpc_clone_client_set_auth(clnt, pflavor); 219 if (IS_ERR(new)) 220 continue; 221 /** 222 * Check that the user actually can use the 223 * flavor. This is mostly for RPC_AUTH_GSS 224 * where cr_init obtains a gss context 225 */ 226 cred = rpcauth_lookupcred(new->cl_auth, 0); 227 if (IS_ERR(cred)) { 228 rpc_shutdown_client(new); 229 continue; 230 } 231 put_rpccred(cred); 232 return new; 233 } 234 } 235 } 236 return ERR_PTR(-EPERM); 237 } 238 239 /** 240 * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup, 241 * return an rpc_clnt that uses the best available security flavor with 242 * respect to the secinfo flavor list and the sec= mount options. 243 * 244 * @clnt: RPC client to clone 245 * @inode: directory inode 246 * @name: lookup name 247 * 248 * Please call rpc_shutdown_client() when you are done with this rpc client. 249 */ 250 struct rpc_clnt * 251 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode, 252 const struct qstr *name) 253 { 254 struct page *page; 255 struct nfs4_secinfo_flavors *flavors; 256 struct rpc_clnt *new; 257 int err; 258 259 page = alloc_page(GFP_KERNEL); 260 if (!page) 261 return ERR_PTR(-ENOMEM); 262 263 flavors = page_address(page); 264 265 err = nfs4_proc_secinfo(inode, name, flavors); 266 if (err < 0) { 267 new = ERR_PTR(err); 268 goto out; 269 } 270 271 new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors); 272 273 out: 274 put_page(page); 275 return new; 276 } 277 278 static int try_location(struct fs_context *fc, 279 const struct nfs4_fs_location *location) 280 { 281 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 282 struct nfs_fs_context *ctx = nfs_fc2context(fc); 283 unsigned int len, s; 284 char *export_path, *source, *p; 285 int ret = -ENOENT; 286 287 /* Allocate a buffer big enough to hold any of the hostnames plus a 288 * terminating char and also a buffer big enough to hold the hostname 289 * plus a colon plus the path. 290 */ 291 len = 0; 292 for (s = 0; s < location->nservers; s++) { 293 const struct nfs4_string *buf = &location->servers[s]; 294 if (buf->len > len) 295 len = buf->len; 296 } 297 298 kfree(ctx->nfs_server.hostname); 299 ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL); 300 if (!ctx->nfs_server.hostname) 301 return -ENOMEM; 302 303 export_path = nfs4_pathname_string(&location->rootpath, 304 &ctx->nfs_server.export_path_len); 305 if (IS_ERR(export_path)) 306 return PTR_ERR(export_path); 307 308 ctx->nfs_server.export_path = export_path; 309 310 source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1, 311 GFP_KERNEL); 312 if (!source) 313 return -ENOMEM; 314 315 kfree(fc->source); 316 fc->source = source; 317 318 ctx->clone_data.addr = kmalloc(addr_bufsize, GFP_KERNEL); 319 if (ctx->clone_data.addr == NULL) 320 return -ENOMEM; 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->clone_data.addrlen = 328 nfs_parse_server_name(buf->data, buf->len, 329 ctx->clone_data.addr, 330 addr_bufsize, 331 fc->net_ns); 332 if (ctx->clone_data.addrlen == 0) 333 continue; 334 335 rpc_set_port(ctx->clone_data.addr, NFS_PORT); 336 337 memcpy(ctx->nfs_server.hostname, buf->data, buf->len); 338 ctx->nfs_server.hostname[buf->len] = '\0'; 339 ctx->clone_data.hostname = ctx->nfs_server.hostname; 340 341 p = source; 342 memcpy(p, buf->data, buf->len); 343 p += buf->len; 344 *p++ = ':'; 345 memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len); 346 p += ctx->nfs_server.export_path_len; 347 *p = 0; 348 349 ret = nfs4_get_referral_tree(fc); 350 if (ret == 0) 351 return 0; 352 } 353 354 return ret; 355 } 356 357 /** 358 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error 359 * @dentry: parent directory 360 * @locations: array of NFSv4 server location information 361 * 362 */ 363 static int nfs_follow_referral(struct fs_context *fc, 364 const struct nfs4_fs_locations *locations) 365 { 366 struct nfs_fs_context *ctx = nfs_fc2context(fc); 367 int loc, error; 368 369 if (locations == NULL || locations->nlocations <= 0) 370 return -ENOENT; 371 372 dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry); 373 374 /* Ensure fs path is a prefix of current dentry path */ 375 error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx); 376 if (error < 0) 377 return error; 378 379 error = -ENOENT; 380 for (loc = 0; loc < locations->nlocations; loc++) { 381 const struct nfs4_fs_location *location = &locations->locations[loc]; 382 383 if (location == NULL || location->nservers <= 0 || 384 location->rootpath.ncomponents == 0) 385 continue; 386 387 error = try_location(fc, location); 388 if (error == 0) 389 return 0; 390 } 391 392 return error; 393 } 394 395 /* 396 * nfs_do_refmount - handle crossing a referral on server 397 * @dentry - dentry of referral 398 * 399 */ 400 static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client) 401 { 402 struct nfs_fs_context *ctx = nfs_fc2context(fc); 403 struct dentry *dentry, *parent; 404 struct nfs4_fs_locations *fs_locations = NULL; 405 struct page *page; 406 int err = -ENOMEM; 407 408 /* BUG_ON(IS_ROOT(dentry)); */ 409 page = alloc_page(GFP_KERNEL); 410 if (!page) 411 return -ENOMEM; 412 413 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL); 414 if (!fs_locations) 415 goto out_free; 416 417 /* Get locations */ 418 dentry = ctx->clone_data.dentry; 419 parent = dget_parent(dentry); 420 dprintk("%s: getting locations for %pd2\n", 421 __func__, dentry); 422 423 err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page); 424 dput(parent); 425 if (err != 0) 426 goto out_free_2; 427 428 err = -ENOENT; 429 if (fs_locations->nlocations <= 0 || 430 fs_locations->fs_path.ncomponents <= 0) 431 goto out_free_2; 432 433 err = nfs_follow_referral(fc, fs_locations); 434 out_free_2: 435 kfree(fs_locations); 436 out_free: 437 __free_page(page); 438 return err; 439 } 440 441 int nfs4_submount(struct fs_context *fc, struct nfs_server *server) 442 { 443 struct nfs_fs_context *ctx = nfs_fc2context(fc); 444 struct dentry *dentry = ctx->clone_data.dentry; 445 struct dentry *parent = dget_parent(dentry); 446 struct inode *dir = d_inode(parent); 447 const struct qstr *name = &dentry->d_name; 448 struct rpc_clnt *client; 449 int ret; 450 451 /* Look it up again to get its attributes and sec flavor */ 452 client = nfs4_proc_lookup_mountpoint(dir, name, ctx->mount_info.mntfh, 453 ctx->clone_data.fattr); 454 dput(parent); 455 if (IS_ERR(client)) 456 return PTR_ERR(client); 457 458 ctx->selected_flavor = client->cl_auth->au_flavor; 459 if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 460 ret = nfs_do_refmount(fc, client); 461 } else { 462 ret = nfs_do_submount(fc); 463 } 464 465 rpc_shutdown_client(client); 466 return ret; 467 } 468 469 /* 470 * Try one location from the fs_locations array. 471 * 472 * Returns zero on success, or a negative errno value. 473 */ 474 static int nfs4_try_replacing_one_location(struct nfs_server *server, 475 char *page, char *page2, 476 const struct nfs4_fs_location *location) 477 { 478 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 479 struct net *net = rpc_net_ns(server->client); 480 struct sockaddr *sap; 481 unsigned int s; 482 size_t salen; 483 int error; 484 485 sap = kmalloc(addr_bufsize, GFP_KERNEL); 486 if (sap == NULL) 487 return -ENOMEM; 488 489 error = -ENOENT; 490 for (s = 0; s < location->nservers; s++) { 491 const struct nfs4_string *buf = &location->servers[s]; 492 char *hostname; 493 494 if (buf->len <= 0 || buf->len > PAGE_SIZE) 495 continue; 496 497 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL) 498 continue; 499 500 salen = nfs_parse_server_name(buf->data, buf->len, 501 sap, addr_bufsize, net); 502 if (salen == 0) 503 continue; 504 rpc_set_port(sap, NFS_PORT); 505 506 error = -ENOMEM; 507 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL); 508 if (hostname == NULL) 509 break; 510 511 error = nfs4_update_server(server, hostname, sap, salen, net); 512 kfree(hostname); 513 if (error == 0) 514 break; 515 } 516 517 kfree(sap); 518 return error; 519 } 520 521 /** 522 * nfs4_replace_transport - set up transport to destination server 523 * 524 * @server: export being migrated 525 * @locations: fs_locations array 526 * 527 * Returns zero on success, or a negative errno value. 528 * 529 * The client tries all the entries in the "locations" array, in the 530 * order returned by the server, until one works or the end of the 531 * array is reached. 532 */ 533 int nfs4_replace_transport(struct nfs_server *server, 534 const struct nfs4_fs_locations *locations) 535 { 536 char *page = NULL, *page2 = NULL; 537 int loc, error; 538 539 error = -ENOENT; 540 if (locations == NULL || locations->nlocations <= 0) 541 goto out; 542 543 error = -ENOMEM; 544 page = (char *) __get_free_page(GFP_USER); 545 if (!page) 546 goto out; 547 page2 = (char *) __get_free_page(GFP_USER); 548 if (!page2) 549 goto out; 550 551 for (loc = 0; loc < locations->nlocations; loc++) { 552 const struct nfs4_fs_location *location = 553 &locations->locations[loc]; 554 555 if (location == NULL || location->nservers <= 0 || 556 location->rootpath.ncomponents == 0) 557 continue; 558 559 error = nfs4_try_replacing_one_location(server, page, 560 page2, location); 561 if (error == 0) 562 break; 563 } 564 565 out: 566 free_page((unsigned long)page); 567 free_page((unsigned long)page2); 568 return error; 569 } 570