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 memcpy(page2, buf->data, buf->len); 274 page2[buf->len] = '\0'; 275 mountdata->hostname = page2; 276 277 snprintf(page, PAGE_SIZE, "%s:%s", 278 mountdata->hostname, 279 mountdata->mnt_path); 280 281 mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata); 282 if (!IS_ERR(mnt)) 283 break; 284 } 285 kfree(mountdata->addr); 286 return mnt; 287 } 288 289 /** 290 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error 291 * @dentry - parent directory 292 * @locations - array of NFSv4 server location information 293 * 294 */ 295 static struct vfsmount *nfs_follow_referral(struct dentry *dentry, 296 const struct nfs4_fs_locations *locations) 297 { 298 struct vfsmount *mnt = ERR_PTR(-ENOENT); 299 struct nfs_clone_mount mountdata = { 300 .sb = dentry->d_sb, 301 .dentry = dentry, 302 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor, 303 }; 304 char *page = NULL, *page2 = NULL; 305 int loc, error; 306 307 if (locations == NULL || locations->nlocations <= 0) 308 goto out; 309 310 dprintk("%s: referral at %pd2\n", __func__, dentry); 311 312 page = (char *) __get_free_page(GFP_USER); 313 if (!page) 314 goto out; 315 316 page2 = (char *) __get_free_page(GFP_USER); 317 if (!page2) 318 goto out; 319 320 /* Ensure fs path is a prefix of current dentry path */ 321 error = nfs4_validate_fspath(dentry, locations, page, page2); 322 if (error < 0) { 323 mnt = ERR_PTR(error); 324 goto out; 325 } 326 327 for (loc = 0; loc < locations->nlocations; loc++) { 328 const struct nfs4_fs_location *location = &locations->locations[loc]; 329 330 if (location == NULL || location->nservers <= 0 || 331 location->rootpath.ncomponents == 0) 332 continue; 333 334 mnt = try_location(&mountdata, page, page2, location); 335 if (!IS_ERR(mnt)) 336 break; 337 } 338 339 out: 340 free_page((unsigned long) page); 341 free_page((unsigned long) page2); 342 return mnt; 343 } 344 345 /* 346 * nfs_do_refmount - handle crossing a referral on server 347 * @dentry - dentry of referral 348 * 349 */ 350 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry) 351 { 352 struct vfsmount *mnt = ERR_PTR(-ENOMEM); 353 struct dentry *parent; 354 struct nfs4_fs_locations *fs_locations = NULL; 355 struct page *page; 356 int err; 357 358 /* BUG_ON(IS_ROOT(dentry)); */ 359 page = alloc_page(GFP_KERNEL); 360 if (page == NULL) 361 return mnt; 362 363 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL); 364 if (fs_locations == NULL) 365 goto out_free; 366 367 /* Get locations */ 368 mnt = ERR_PTR(-ENOENT); 369 370 parent = dget_parent(dentry); 371 dprintk("%s: getting locations for %pd2\n", 372 __func__, dentry); 373 374 err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page); 375 dput(parent); 376 if (err != 0 || 377 fs_locations->nlocations <= 0 || 378 fs_locations->fs_path.ncomponents <= 0) 379 goto out_free; 380 381 mnt = nfs_follow_referral(dentry, fs_locations); 382 out_free: 383 __free_page(page); 384 kfree(fs_locations); 385 return mnt; 386 } 387 388 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry, 389 struct nfs_fh *fh, struct nfs_fattr *fattr) 390 { 391 rpc_authflavor_t flavor = server->client->cl_auth->au_flavor; 392 struct dentry *parent = dget_parent(dentry); 393 struct inode *dir = d_inode(parent); 394 const struct qstr *name = &dentry->d_name; 395 struct rpc_clnt *client; 396 struct vfsmount *mnt; 397 398 /* Look it up again to get its attributes and sec flavor */ 399 client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr); 400 dput(parent); 401 if (IS_ERR(client)) 402 return ERR_CAST(client); 403 404 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 405 mnt = nfs_do_refmount(client, dentry); 406 goto out; 407 } 408 409 if (client->cl_auth->au_flavor != flavor) 410 flavor = client->cl_auth->au_flavor; 411 mnt = nfs_do_submount(dentry, fh, fattr, flavor); 412 out: 413 rpc_shutdown_client(client); 414 return mnt; 415 } 416 417 /* 418 * Try one location from the fs_locations array. 419 * 420 * Returns zero on success, or a negative errno value. 421 */ 422 static int nfs4_try_replacing_one_location(struct nfs_server *server, 423 char *page, char *page2, 424 const struct nfs4_fs_location *location) 425 { 426 const size_t addr_bufsize = sizeof(struct sockaddr_storage); 427 struct net *net = rpc_net_ns(server->client); 428 struct sockaddr *sap; 429 unsigned int s; 430 size_t salen; 431 int error; 432 433 sap = kmalloc(addr_bufsize, GFP_KERNEL); 434 if (sap == NULL) 435 return -ENOMEM; 436 437 error = -ENOENT; 438 for (s = 0; s < location->nservers; s++) { 439 const struct nfs4_string *buf = &location->servers[s]; 440 char *hostname; 441 442 if (buf->len <= 0 || buf->len > PAGE_SIZE) 443 continue; 444 445 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL) 446 continue; 447 448 salen = nfs_parse_server_name(buf->data, buf->len, 449 sap, addr_bufsize, net); 450 if (salen == 0) 451 continue; 452 rpc_set_port(sap, NFS_PORT); 453 454 error = -ENOMEM; 455 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL); 456 if (hostname == NULL) 457 break; 458 459 error = nfs4_update_server(server, hostname, sap, salen, net); 460 kfree(hostname); 461 if (error == 0) 462 break; 463 } 464 465 kfree(sap); 466 return error; 467 } 468 469 /** 470 * nfs4_replace_transport - set up transport to destination server 471 * 472 * @server: export being migrated 473 * @locations: fs_locations array 474 * 475 * Returns zero on success, or a negative errno value. 476 * 477 * The client tries all the entries in the "locations" array, in the 478 * order returned by the server, until one works or the end of the 479 * array is reached. 480 */ 481 int nfs4_replace_transport(struct nfs_server *server, 482 const struct nfs4_fs_locations *locations) 483 { 484 char *page = NULL, *page2 = NULL; 485 int loc, error; 486 487 error = -ENOENT; 488 if (locations == NULL || locations->nlocations <= 0) 489 goto out; 490 491 error = -ENOMEM; 492 page = (char *) __get_free_page(GFP_USER); 493 if (!page) 494 goto out; 495 page2 = (char *) __get_free_page(GFP_USER); 496 if (!page2) 497 goto out; 498 499 for (loc = 0; loc < locations->nlocations; loc++) { 500 const struct nfs4_fs_location *location = 501 &locations->locations[loc]; 502 503 if (location == NULL || location->nservers <= 0 || 504 location->rootpath.ncomponents == 0) 505 continue; 506 507 error = nfs4_try_replacing_one_location(server, page, 508 page2, location); 509 if (error == 0) 510 break; 511 } 512 513 out: 514 free_page((unsigned long)page); 515 free_page((unsigned long)page2); 516 return error; 517 } 518