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/dcache.h> 12 #include <linux/mount.h> 13 #include <linux/namei.h> 14 #include <linux/nfs_fs.h> 15 #include <linux/nfs_mount.h> 16 #include <linux/slab.h> 17 #include <linux/string.h> 18 #include <linux/sunrpc/clnt.h> 19 #include <linux/sunrpc/addr.h> 20 #include <linux/vfs.h> 21 #include <linux/inet.h> 22 #include "internal.h" 23 #include "nfs4_fs.h" 24 #include "dns_resolve.h" 25 26 #define NFSDBG_FACILITY NFSDBG_VFS 27 28 /* 29 * Convert the NFSv4 pathname components into a standard posix path. 30 * 31 * Note that the resulting string will be placed at the end of the buffer 32 */ 33 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname, 34 char *buffer, ssize_t buflen) 35 { 36 char *end = buffer + buflen; 37 int n; 38 39 *--end = '\0'; 40 buflen--; 41 42 n = pathname->ncomponents; 43 while (--n >= 0) { 44 const struct nfs4_string *component = &pathname->components[n]; 45 buflen -= component->len + 1; 46 if (buflen < 0) 47 goto Elong; 48 end -= component->len; 49 memcpy(end, component->data, component->len); 50 *--end = '/'; 51 } 52 return end; 53 Elong: 54 return ERR_PTR(-ENAMETOOLONG); 55 } 56 57 /* 58 * return the path component of "<server>:<path>" 59 * nfspath - the "<server>:<path>" string 60 * end - one past the last char that could contain "<server>:" 61 * returns NULL on failure 62 */ 63 static char *nfs_path_component(const char *nfspath, const char *end) 64 { 65 char *p; 66 67 if (*nfspath == '[') { 68 /* parse [] escaped IPv6 addrs */ 69 p = strchr(nfspath, ']'); 70 if (p != NULL && ++p < end && *p == ':') 71 return p + 1; 72 } else { 73 /* otherwise split on first colon */ 74 p = strchr(nfspath, ':'); 75 if (p != NULL && p < end) 76 return p + 1; 77 } 78 return NULL; 79 } 80 81 /* 82 * Determine the mount path as a string 83 */ 84 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen) 85 { 86 char *limit; 87 char *path = nfs_path(&limit, dentry, buffer, buflen, 88 NFS_PATH_CANONICAL); 89 if (!IS_ERR(path)) { 90 char *path_component = nfs_path_component(path, limit); 91 if (path_component) 92 return path_component; 93 } 94 return path; 95 } 96 97 /* 98 * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we 99 * believe to be the server path to this dentry 100 */ 101 static int nfs4_validate_fspath(struct dentry *dentry, 102 const struct nfs4_fs_locations *locations, 103 char *page, char *page2) 104 { 105 const char *path, *fs_path; 106 107 path = nfs4_path(dentry, page, PAGE_SIZE); 108 if (IS_ERR(path)) 109 return PTR_ERR(path); 110 111 fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE); 112 if (IS_ERR(fs_path)) 113 return PTR_ERR(fs_path); 114 115 if (strncmp(path, fs_path, strlen(fs_path)) != 0) { 116 dprintk("%s: path %s does not begin with fsroot %s\n", 117 __func__, path, fs_path); 118 return -ENOENT; 119 } 120 121 return 0; 122 } 123 124 static size_t nfs_parse_server_name(char *string, size_t len, 125 struct sockaddr *sa, size_t salen, struct net *net) 126 { 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 * @clnt: pointer to rpc_clnt 141 * @server: NFS server struct 142 * @flavors: List of security tuples returned by SECINFO procedure 143 * 144 * Return an rpc client that uses the first security mechanism in 145 * "flavors" that is locally supported. The "flavors" array 146 * is searched in the order returned from the server, per RFC 3530 147 * recommendation and each flavor is checked for membership in the 148 * sec= mount option list if it exists. 149 * 150 * Return -EPERM if no matching flavor is found in the array. 151 * 152 * Please call rpc_shutdown_client() when you are done with this rpc client. 153 * 154 */ 155 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt, 156 struct nfs_server *server, 157 struct nfs4_secinfo_flavors *flavors) 158 { 159 rpc_authflavor_t pflavor; 160 struct nfs4_secinfo4 *secinfo; 161 unsigned int i; 162 163 for (i = 0; i < flavors->num_flavors; i++) { 164 secinfo = &flavors->flavors[i]; 165 166 switch (secinfo->flavor) { 167 case RPC_AUTH_NULL: 168 case RPC_AUTH_UNIX: 169 case RPC_AUTH_GSS: 170 pflavor = rpcauth_get_pseudoflavor(secinfo->flavor, 171 &secinfo->flavor_info); 172 /* does the pseudoflavor match a sec= mount opt? */ 173 if (pflavor != RPC_AUTH_MAXFLAVOR && 174 nfs_auth_info_match(&server->auth_info, pflavor)) { 175 struct rpc_clnt *new; 176 struct rpc_cred *cred; 177 178 /* Cloning creates an rpc_auth for the flavor */ 179 new = rpc_clone_client_set_auth(clnt, pflavor); 180 if (IS_ERR(new)) 181 continue; 182 /** 183 * Check that the user actually can use the 184 * flavor. This is mostly for RPC_AUTH_GSS 185 * where cr_init obtains a gss context 186 */ 187 cred = rpcauth_lookupcred(new->cl_auth, 0); 188 if (IS_ERR(cred)) { 189 rpc_shutdown_client(new); 190 continue; 191 } 192 put_rpccred(cred); 193 return new; 194 } 195 } 196 } 197 return ERR_PTR(-EPERM); 198 } 199 200 /** 201 * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup, 202 * return an rpc_clnt that uses the best available security flavor with 203 * respect to the secinfo flavor list and the sec= mount options. 204 * 205 * @clnt: RPC client to clone 206 * @inode: directory inode 207 * @name: lookup name 208 * 209 * Please call rpc_shutdown_client() when you are done with this rpc client. 210 */ 211 struct rpc_clnt * 212 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode, 213 const struct qstr *name) 214 { 215 struct page *page; 216 struct nfs4_secinfo_flavors *flavors; 217 struct rpc_clnt *new; 218 int err; 219 220 page = alloc_page(GFP_KERNEL); 221 if (!page) 222 return ERR_PTR(-ENOMEM); 223 224 flavors = page_address(page); 225 226 err = nfs4_proc_secinfo(inode, name, flavors); 227 if (err < 0) { 228 new = ERR_PTR(err); 229 goto out; 230 } 231 232 new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors); 233 234 out: 235 put_page(page); 236 return new; 237 } 238 239 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata, 240 char *page, char *page2, 241 const struct nfs4_fs_location *location) 242 { 243 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 244 struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client); 245 struct vfsmount *mnt = ERR_PTR(-ENOENT); 246 char *mnt_path; 247 unsigned int maxbuflen; 248 unsigned int s; 249 250 mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE); 251 if (IS_ERR(mnt_path)) 252 return ERR_CAST(mnt_path); 253 mountdata->mnt_path = mnt_path; 254 maxbuflen = mnt_path - 1 - page2; 255 256 mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL); 257 if (mountdata->addr == NULL) 258 return ERR_PTR(-ENOMEM); 259 260 for (s = 0; s < location->nservers; s++) { 261 const struct nfs4_string *buf = &location->servers[s]; 262 263 if (buf->len <= 0 || buf->len >= maxbuflen) 264 continue; 265 266 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len)) 267 continue; 268 269 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len, 270 mountdata->addr, addr_bufsize, net); 271 if (mountdata->addrlen == 0) 272 continue; 273 274 memcpy(page2, buf->data, buf->len); 275 page2[buf->len] = '\0'; 276 mountdata->hostname = page2; 277 278 snprintf(page, PAGE_SIZE, "%s:%s", 279 mountdata->hostname, 280 mountdata->mnt_path); 281 282 mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata); 283 if (!IS_ERR(mnt)) 284 break; 285 } 286 kfree(mountdata->addr); 287 return mnt; 288 } 289 290 /** 291 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error 292 * @dentry: parent directory 293 * @locations: array of NFSv4 server location information 294 * 295 */ 296 static struct vfsmount *nfs_follow_referral(struct dentry *dentry, 297 const struct nfs4_fs_locations *locations) 298 { 299 struct vfsmount *mnt = ERR_PTR(-ENOENT); 300 struct nfs_clone_mount mountdata = { 301 .sb = dentry->d_sb, 302 .dentry = dentry, 303 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor, 304 }; 305 char *page = NULL, *page2 = NULL; 306 int loc, error; 307 308 if (locations == NULL || locations->nlocations <= 0) 309 goto out; 310 311 dprintk("%s: referral at %pd2\n", __func__, dentry); 312 313 page = (char *) __get_free_page(GFP_USER); 314 if (!page) 315 goto out; 316 317 page2 = (char *) __get_free_page(GFP_USER); 318 if (!page2) 319 goto out; 320 321 /* Ensure fs path is a prefix of current dentry path */ 322 error = nfs4_validate_fspath(dentry, locations, page, page2); 323 if (error < 0) { 324 mnt = ERR_PTR(error); 325 goto out; 326 } 327 328 for (loc = 0; loc < locations->nlocations; loc++) { 329 const struct nfs4_fs_location *location = &locations->locations[loc]; 330 331 if (location == NULL || location->nservers <= 0 || 332 location->rootpath.ncomponents == 0) 333 continue; 334 335 mnt = try_location(&mountdata, page, page2, location); 336 if (!IS_ERR(mnt)) 337 break; 338 } 339 340 out: 341 free_page((unsigned long) page); 342 free_page((unsigned long) page2); 343 return mnt; 344 } 345 346 /* 347 * nfs_do_refmount - handle crossing a referral on server 348 * @dentry - dentry of referral 349 * 350 */ 351 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry) 352 { 353 struct vfsmount *mnt = ERR_PTR(-ENOMEM); 354 struct dentry *parent; 355 struct nfs4_fs_locations *fs_locations = NULL; 356 struct page *page; 357 int err; 358 359 /* BUG_ON(IS_ROOT(dentry)); */ 360 page = alloc_page(GFP_KERNEL); 361 if (page == NULL) 362 return mnt; 363 364 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL); 365 if (fs_locations == NULL) 366 goto out_free; 367 368 /* Get locations */ 369 mnt = ERR_PTR(-ENOENT); 370 371 parent = dget_parent(dentry); 372 dprintk("%s: getting locations for %pd2\n", 373 __func__, dentry); 374 375 err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page); 376 dput(parent); 377 if (err != 0 || 378 fs_locations->nlocations <= 0 || 379 fs_locations->fs_path.ncomponents <= 0) 380 goto out_free; 381 382 mnt = nfs_follow_referral(dentry, fs_locations); 383 out_free: 384 __free_page(page); 385 kfree(fs_locations); 386 return mnt; 387 } 388 389 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry, 390 struct nfs_fh *fh, struct nfs_fattr *fattr) 391 { 392 rpc_authflavor_t flavor = server->client->cl_auth->au_flavor; 393 struct dentry *parent = dget_parent(dentry); 394 struct inode *dir = d_inode(parent); 395 const struct qstr *name = &dentry->d_name; 396 struct rpc_clnt *client; 397 struct vfsmount *mnt; 398 399 /* Look it up again to get its attributes and sec flavor */ 400 client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr); 401 dput(parent); 402 if (IS_ERR(client)) 403 return ERR_CAST(client); 404 405 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 406 mnt = nfs_do_refmount(client, dentry); 407 goto out; 408 } 409 410 if (client->cl_auth->au_flavor != flavor) 411 flavor = client->cl_auth->au_flavor; 412 mnt = nfs_do_submount(dentry, fh, fattr, flavor); 413 out: 414 rpc_shutdown_client(client); 415 return mnt; 416 } 417 418 /* 419 * Try one location from the fs_locations array. 420 * 421 * Returns zero on success, or a negative errno value. 422 */ 423 static int nfs4_try_replacing_one_location(struct nfs_server *server, 424 char *page, char *page2, 425 const struct nfs4_fs_location *location) 426 { 427 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 428 struct net *net = rpc_net_ns(server->client); 429 struct sockaddr *sap; 430 unsigned int s; 431 size_t salen; 432 int error; 433 434 sap = kmalloc(addr_bufsize, GFP_KERNEL); 435 if (sap == NULL) 436 return -ENOMEM; 437 438 error = -ENOENT; 439 for (s = 0; s < location->nservers; s++) { 440 const struct nfs4_string *buf = &location->servers[s]; 441 char *hostname; 442 443 if (buf->len <= 0 || buf->len > PAGE_SIZE) 444 continue; 445 446 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL) 447 continue; 448 449 salen = nfs_parse_server_name(buf->data, buf->len, 450 sap, addr_bufsize, net); 451 if (salen == 0) 452 continue; 453 rpc_set_port(sap, NFS_PORT); 454 455 error = -ENOMEM; 456 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL); 457 if (hostname == NULL) 458 break; 459 460 error = nfs4_update_server(server, hostname, sap, salen, net); 461 kfree(hostname); 462 if (error == 0) 463 break; 464 } 465 466 kfree(sap); 467 return error; 468 } 469 470 /** 471 * nfs4_replace_transport - set up transport to destination server 472 * 473 * @server: export being migrated 474 * @locations: fs_locations array 475 * 476 * Returns zero on success, or a negative errno value. 477 * 478 * The client tries all the entries in the "locations" array, in the 479 * order returned by the server, until one works or the end of the 480 * array is reached. 481 */ 482 int nfs4_replace_transport(struct nfs_server *server, 483 const struct nfs4_fs_locations *locations) 484 { 485 char *page = NULL, *page2 = NULL; 486 int loc, error; 487 488 error = -ENOENT; 489 if (locations == NULL || locations->nlocations <= 0) 490 goto out; 491 492 error = -ENOMEM; 493 page = (char *) __get_free_page(GFP_USER); 494 if (!page) 495 goto out; 496 page2 = (char *) __get_free_page(GFP_USER); 497 if (!page2) 498 goto out; 499 500 for (loc = 0; loc < locations->nlocations; loc++) { 501 const struct nfs4_fs_location *location = 502 &locations->locations[loc]; 503 504 if (location == NULL || location->nservers <= 0 || 505 location->rootpath.ncomponents == 0) 506 continue; 507 508 error = nfs4_try_replacing_one_location(server, page, 509 page2, location); 510 if (error == 0) 511 break; 512 } 513 514 out: 515 free_page((unsigned long)page); 516 free_page((unsigned long)page2); 517 return error; 518 } 519