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 * @server: NFS server struct 141 * @flavors: List of security tuples returned by SECINFO procedure 142 * 143 * Return an rpc client that uses the first security mechanism in 144 * "flavors" that is locally supported. The "flavors" array 145 * is searched in the order returned from the server, per RFC 3530 146 * recommendation and each flavor is checked for membership in the 147 * sec= mount option list if it exists. 148 * 149 * Return -EPERM if no matching flavor is found in the array. 150 * 151 * Please call rpc_shutdown_client() when you are done with this rpc client. 152 * 153 */ 154 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt, 155 struct nfs_server *server, 156 struct nfs4_secinfo_flavors *flavors) 157 { 158 rpc_authflavor_t pflavor; 159 struct nfs4_secinfo4 *secinfo; 160 unsigned int i; 161 162 for (i = 0; i < flavors->num_flavors; i++) { 163 secinfo = &flavors->flavors[i]; 164 165 switch (secinfo->flavor) { 166 case RPC_AUTH_NULL: 167 case RPC_AUTH_UNIX: 168 case RPC_AUTH_GSS: 169 pflavor = rpcauth_get_pseudoflavor(secinfo->flavor, 170 &secinfo->flavor_info); 171 /* does the pseudoflavor match a sec= mount opt? */ 172 if (pflavor != RPC_AUTH_MAXFLAVOR && 173 nfs_auth_info_match(&server->auth_info, pflavor)) { 174 struct rpc_clnt *new; 175 struct rpc_cred *cred; 176 177 /* Cloning creates an rpc_auth for the flavor */ 178 new = rpc_clone_client_set_auth(clnt, pflavor); 179 if (IS_ERR(new)) 180 continue; 181 /** 182 * Check that the user actually can use the 183 * flavor. This is mostly for RPC_AUTH_GSS 184 * where cr_init obtains a gss context 185 */ 186 cred = rpcauth_lookupcred(new->cl_auth, 0); 187 if (IS_ERR(cred)) { 188 rpc_shutdown_client(new); 189 continue; 190 } 191 put_rpccred(cred); 192 return new; 193 } 194 } 195 } 196 return ERR_PTR(-EPERM); 197 } 198 199 /** 200 * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup, 201 * return an rpc_clnt that uses the best available security flavor with 202 * respect to the secinfo flavor list and the sec= mount options. 203 * 204 * @clnt: RPC client to clone 205 * @inode: directory inode 206 * @name: lookup name 207 * 208 * Please call rpc_shutdown_client() when you are done with this rpc client. 209 */ 210 struct rpc_clnt * 211 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode, 212 const struct qstr *name) 213 { 214 struct page *page; 215 struct nfs4_secinfo_flavors *flavors; 216 struct rpc_clnt *new; 217 int err; 218 219 page = alloc_page(GFP_KERNEL); 220 if (!page) 221 return ERR_PTR(-ENOMEM); 222 223 flavors = page_address(page); 224 225 err = nfs4_proc_secinfo(inode, name, flavors); 226 if (err < 0) { 227 new = ERR_PTR(err); 228 goto out; 229 } 230 231 new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors); 232 233 out: 234 put_page(page); 235 return new; 236 } 237 238 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata, 239 char *page, char *page2, 240 const struct nfs4_fs_location *location) 241 { 242 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 243 struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client); 244 struct vfsmount *mnt = ERR_PTR(-ENOENT); 245 char *mnt_path; 246 unsigned int maxbuflen; 247 unsigned int s; 248 249 mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE); 250 if (IS_ERR(mnt_path)) 251 return ERR_CAST(mnt_path); 252 mountdata->mnt_path = mnt_path; 253 maxbuflen = mnt_path - 1 - page2; 254 255 mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL); 256 if (mountdata->addr == NULL) 257 return ERR_PTR(-ENOMEM); 258 259 for (s = 0; s < location->nservers; s++) { 260 const struct nfs4_string *buf = &location->servers[s]; 261 262 if (buf->len <= 0 || buf->len >= maxbuflen) 263 continue; 264 265 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len)) 266 continue; 267 268 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len, 269 mountdata->addr, addr_bufsize, net); 270 if (mountdata->addrlen == 0) 271 continue; 272 273 rpc_set_port(mountdata->addr, NFS_PORT); 274 275 memcpy(page2, buf->data, buf->len); 276 page2[buf->len] = '\0'; 277 mountdata->hostname = page2; 278 279 snprintf(page, PAGE_SIZE, "%s:%s", 280 mountdata->hostname, 281 mountdata->mnt_path); 282 283 mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata); 284 if (!IS_ERR(mnt)) 285 break; 286 } 287 kfree(mountdata->addr); 288 return mnt; 289 } 290 291 /** 292 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error 293 * @dentry - parent directory 294 * @locations - array of NFSv4 server location information 295 * 296 */ 297 static struct vfsmount *nfs_follow_referral(struct dentry *dentry, 298 const struct nfs4_fs_locations *locations) 299 { 300 struct vfsmount *mnt = ERR_PTR(-ENOENT); 301 struct nfs_clone_mount mountdata = { 302 .sb = dentry->d_sb, 303 .dentry = dentry, 304 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor, 305 }; 306 char *page = NULL, *page2 = NULL; 307 int loc, error; 308 309 if (locations == NULL || locations->nlocations <= 0) 310 goto out; 311 312 dprintk("%s: referral at %pd2\n", __func__, dentry); 313 314 page = (char *) __get_free_page(GFP_USER); 315 if (!page) 316 goto out; 317 318 page2 = (char *) __get_free_page(GFP_USER); 319 if (!page2) 320 goto out; 321 322 /* Ensure fs path is a prefix of current dentry path */ 323 error = nfs4_validate_fspath(dentry, locations, page, page2); 324 if (error < 0) { 325 mnt = ERR_PTR(error); 326 goto out; 327 } 328 329 for (loc = 0; loc < locations->nlocations; loc++) { 330 const struct nfs4_fs_location *location = &locations->locations[loc]; 331 332 if (location == NULL || location->nservers <= 0 || 333 location->rootpath.ncomponents == 0) 334 continue; 335 336 mnt = try_location(&mountdata, page, page2, location); 337 if (!IS_ERR(mnt)) 338 break; 339 } 340 341 out: 342 free_page((unsigned long) page); 343 free_page((unsigned long) page2); 344 return mnt; 345 } 346 347 /* 348 * nfs_do_refmount - handle crossing a referral on server 349 * @dentry - dentry of referral 350 * 351 */ 352 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry) 353 { 354 struct vfsmount *mnt = ERR_PTR(-ENOMEM); 355 struct dentry *parent; 356 struct nfs4_fs_locations *fs_locations = NULL; 357 struct page *page; 358 int err; 359 360 /* BUG_ON(IS_ROOT(dentry)); */ 361 page = alloc_page(GFP_KERNEL); 362 if (page == NULL) 363 return mnt; 364 365 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL); 366 if (fs_locations == NULL) 367 goto out_free; 368 369 /* Get locations */ 370 mnt = ERR_PTR(-ENOENT); 371 372 parent = dget_parent(dentry); 373 dprintk("%s: getting locations for %pd2\n", 374 __func__, dentry); 375 376 err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page); 377 dput(parent); 378 if (err != 0 || 379 fs_locations->nlocations <= 0 || 380 fs_locations->fs_path.ncomponents <= 0) 381 goto out_free; 382 383 mnt = nfs_follow_referral(dentry, fs_locations); 384 out_free: 385 __free_page(page); 386 kfree(fs_locations); 387 return mnt; 388 } 389 390 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry, 391 struct nfs_fh *fh, struct nfs_fattr *fattr) 392 { 393 rpc_authflavor_t flavor = server->client->cl_auth->au_flavor; 394 struct dentry *parent = dget_parent(dentry); 395 struct inode *dir = d_inode(parent); 396 const struct qstr *name = &dentry->d_name; 397 struct rpc_clnt *client; 398 struct vfsmount *mnt; 399 400 /* Look it up again to get its attributes and sec flavor */ 401 client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr); 402 dput(parent); 403 if (IS_ERR(client)) 404 return ERR_CAST(client); 405 406 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 407 mnt = nfs_do_refmount(client, dentry); 408 goto out; 409 } 410 411 if (client->cl_auth->au_flavor != flavor) 412 flavor = client->cl_auth->au_flavor; 413 mnt = nfs_do_submount(dentry, fh, fattr, flavor); 414 out: 415 rpc_shutdown_client(client); 416 return mnt; 417 } 418 419 /* 420 * Try one location from the fs_locations array. 421 * 422 * Returns zero on success, or a negative errno value. 423 */ 424 static int nfs4_try_replacing_one_location(struct nfs_server *server, 425 char *page, char *page2, 426 const struct nfs4_fs_location *location) 427 { 428 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 429 struct net *net = rpc_net_ns(server->client); 430 struct sockaddr *sap; 431 unsigned int s; 432 size_t salen; 433 int error; 434 435 sap = kmalloc(addr_bufsize, GFP_KERNEL); 436 if (sap == NULL) 437 return -ENOMEM; 438 439 error = -ENOENT; 440 for (s = 0; s < location->nservers; s++) { 441 const struct nfs4_string *buf = &location->servers[s]; 442 char *hostname; 443 444 if (buf->len <= 0 || buf->len > PAGE_SIZE) 445 continue; 446 447 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL) 448 continue; 449 450 salen = nfs_parse_server_name(buf->data, buf->len, 451 sap, addr_bufsize, net); 452 if (salen == 0) 453 continue; 454 rpc_set_port(sap, NFS_PORT); 455 456 error = -ENOMEM; 457 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL); 458 if (hostname == NULL) 459 break; 460 461 error = nfs4_update_server(server, hostname, sap, salen, net); 462 kfree(hostname); 463 if (error == 0) 464 break; 465 } 466 467 kfree(sap); 468 return error; 469 } 470 471 /** 472 * nfs4_replace_transport - set up transport to destination server 473 * 474 * @server: export being migrated 475 * @locations: fs_locations array 476 * 477 * Returns zero on success, or a negative errno value. 478 * 479 * The client tries all the entries in the "locations" array, in the 480 * order returned by the server, until one works or the end of the 481 * array is reached. 482 */ 483 int nfs4_replace_transport(struct nfs_server *server, 484 const struct nfs4_fs_locations *locations) 485 { 486 char *page = NULL, *page2 = NULL; 487 int loc, error; 488 489 error = -ENOENT; 490 if (locations == NULL || locations->nlocations <= 0) 491 goto out; 492 493 error = -ENOMEM; 494 page = (char *) __get_free_page(GFP_USER); 495 if (!page) 496 goto out; 497 page2 = (char *) __get_free_page(GFP_USER); 498 if (!page2) 499 goto out; 500 501 for (loc = 0; loc < locations->nlocations; loc++) { 502 const struct nfs4_fs_location *location = 503 &locations->locations[loc]; 504 505 if (location == NULL || location->nservers <= 0 || 506 location->rootpath.ncomponents == 0) 507 continue; 508 509 error = nfs4_try_replacing_one_location(server, page, 510 page2, location); 511 if (error == 0) 512 break; 513 } 514 515 out: 516 free_page((unsigned long)page); 517 free_page((unsigned long)page2); 518 return error; 519 } 520