1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * NFS server file handle treatment. 4 * 5 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> 6 * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org> 7 * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999 8 * ... and again Southern-Winter 2001 to support export_operations 9 */ 10 11 #include <linux/exportfs.h> 12 13 #include <linux/sunrpc/svcauth_gss.h> 14 #include "nfsd.h" 15 #include "vfs.h" 16 #include "auth.h" 17 #include "trace.h" 18 19 #define NFSDDBG_FACILITY NFSDDBG_FH 20 21 22 /* 23 * our acceptability function. 24 * if NOSUBTREECHECK, accept anything 25 * if not, require that we can walk up to exp->ex_dentry 26 * doing some checks on the 'x' bits 27 */ 28 static int nfsd_acceptable(void *expv, struct dentry *dentry) 29 { 30 struct svc_export *exp = expv; 31 int rv; 32 struct dentry *tdentry; 33 struct dentry *parent; 34 35 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) 36 return 1; 37 38 tdentry = dget(dentry); 39 while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) { 40 /* make sure parents give x permission to user */ 41 int err; 42 parent = dget_parent(tdentry); 43 err = inode_permission(&nop_mnt_idmap, 44 d_inode(parent), MAY_EXEC); 45 if (err < 0) { 46 dput(parent); 47 break; 48 } 49 dput(tdentry); 50 tdentry = parent; 51 } 52 if (tdentry != exp->ex_path.dentry) 53 dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry); 54 rv = (tdentry == exp->ex_path.dentry); 55 dput(tdentry); 56 return rv; 57 } 58 59 /* Type check. The correct error return for type mismatches does not seem to be 60 * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a 61 * comment in the NFSv3 spec says this is incorrect (implementation notes for 62 * the write call). 63 */ 64 static inline __be32 65 nfsd_mode_check(struct dentry *dentry, umode_t requested) 66 { 67 umode_t mode = d_inode(dentry)->i_mode & S_IFMT; 68 69 if (requested == 0) /* the caller doesn't care */ 70 return nfs_ok; 71 if (mode == requested) { 72 if (mode == S_IFDIR && !d_can_lookup(dentry)) { 73 WARN_ON_ONCE(1); 74 return nfserr_notdir; 75 } 76 return nfs_ok; 77 } 78 if (mode == S_IFLNK) { 79 if (requested == S_IFDIR) 80 return nfserr_symlink_not_dir; 81 return nfserr_symlink; 82 } 83 if (requested == S_IFDIR) 84 return nfserr_notdir; 85 if (mode == S_IFDIR) 86 return nfserr_isdir; 87 return nfserr_wrong_type; 88 } 89 90 static bool nfsd_originating_port_ok(struct svc_rqst *rqstp, 91 struct svc_cred *cred, 92 struct svc_export *exp) 93 { 94 if (nfsexp_flags(cred, exp) & NFSEXP_INSECURE_PORT) 95 return true; 96 /* We don't require gss requests to use low ports: */ 97 if (cred->cr_flavor >= RPC_AUTH_GSS) 98 return true; 99 return test_bit(RQ_SECURE, &rqstp->rq_flags); 100 } 101 102 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp, 103 struct svc_cred *cred, 104 struct svc_export *exp) 105 { 106 /* Check if the request originated from a secure port. */ 107 if (rqstp && !nfsd_originating_port_ok(rqstp, cred, exp)) { 108 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]); 109 dprintk("nfsd: request from insecure port %s!\n", 110 svc_print_addr(rqstp, buf, sizeof(buf))); 111 return nfserr_perm; 112 } 113 114 /* Set user creds for this exportpoint */ 115 return nfserrno(nfsd_setuser(cred, exp)); 116 } 117 118 static inline __be32 check_pseudo_root(struct dentry *dentry, 119 struct svc_export *exp) 120 { 121 if (!(exp->ex_flags & NFSEXP_V4ROOT)) 122 return nfs_ok; 123 /* 124 * We're exposing only the directories and symlinks that have to be 125 * traversed on the way to real exports: 126 */ 127 if (unlikely(!d_is_dir(dentry) && 128 !d_is_symlink(dentry))) 129 return nfserr_stale; 130 /* 131 * A pseudoroot export gives permission to access only one 132 * single directory; the kernel has to make another upcall 133 * before granting access to anything else under it: 134 */ 135 if (unlikely(dentry != exp->ex_path.dentry)) 136 return nfserr_stale; 137 return nfs_ok; 138 } 139 140 /* 141 * Use the given filehandle to look up the corresponding export and 142 * dentry. On success, the results are used to set fh_export and 143 * fh_dentry. 144 */ 145 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct net *net, 146 struct svc_cred *cred, 147 struct auth_domain *client, 148 struct auth_domain *gssclient, 149 struct svc_fh *fhp) 150 { 151 struct knfsd_fh *fh = &fhp->fh_handle; 152 struct fid *fid = NULL; 153 struct svc_export *exp; 154 struct dentry *dentry; 155 int fileid_type; 156 int data_left = fh->fh_size/4; 157 int len; 158 __be32 error; 159 160 error = nfserr_badhandle; 161 if (fh->fh_size == 0) 162 return nfserr_nofilehandle; 163 164 if (fh->fh_version != 1) 165 return error; 166 167 if (--data_left < 0) 168 return error; 169 if (fh->fh_auth_type != 0) 170 return error; 171 len = key_len(fh->fh_fsid_type) / 4; 172 if (len == 0) 173 return error; 174 if (fh->fh_fsid_type == FSID_MAJOR_MINOR) { 175 /* deprecated, convert to type 3 */ 176 len = key_len(FSID_ENCODE_DEV)/4; 177 fh->fh_fsid_type = FSID_ENCODE_DEV; 178 /* 179 * struct knfsd_fh uses host-endian fields, which are 180 * sometimes used to hold net-endian values. This 181 * confuses sparse, so we must use __force here to 182 * keep it from complaining. 183 */ 184 fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]), 185 ntohl((__force __be32)fh->fh_fsid[1]))); 186 fh->fh_fsid[1] = fh->fh_fsid[2]; 187 } 188 data_left -= len; 189 if (data_left < 0) 190 return error; 191 exp = rqst_exp_find(rqstp ? &rqstp->rq_chandle : NULL, 192 net, client, gssclient, 193 fh->fh_fsid_type, fh->fh_fsid); 194 fid = (struct fid *)(fh->fh_fsid + len); 195 196 error = nfserr_stale; 197 if (IS_ERR(exp)) { 198 trace_nfsd_set_fh_dentry_badexport(rqstp, fhp, PTR_ERR(exp)); 199 200 if (PTR_ERR(exp) == -ENOENT) 201 return error; 202 203 return nfserrno(PTR_ERR(exp)); 204 } 205 206 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) { 207 /* Elevate privileges so that the lack of 'r' or 'x' 208 * permission on some parent directory will 209 * not stop exportfs_decode_fh from being able 210 * to reconnect a directory into the dentry cache. 211 * The same problem can affect "SUBTREECHECK" exports, 212 * but as nfsd_acceptable depends on correct 213 * access control settings being in effect, we cannot 214 * fix that case easily. 215 */ 216 struct cred *new = prepare_creds(); 217 if (!new) { 218 error = nfserrno(-ENOMEM); 219 goto out; 220 } 221 new->cap_effective = 222 cap_raise_nfsd_set(new->cap_effective, 223 new->cap_permitted); 224 put_cred(override_creds(new)); 225 } else { 226 error = nfsd_setuser_and_check_port(rqstp, cred, exp); 227 if (error) 228 goto out; 229 } 230 231 /* 232 * Look up the dentry using the NFS file handle. 233 */ 234 error = nfserr_badhandle; 235 236 fileid_type = fh->fh_fileid_type; 237 238 if (fileid_type == FILEID_ROOT) 239 dentry = dget(exp->ex_path.dentry); 240 else { 241 dentry = exportfs_decode_fh_raw(exp->ex_path.mnt, fid, 242 data_left, fileid_type, 0, 243 nfsd_acceptable, exp); 244 if (IS_ERR_OR_NULL(dentry)) { 245 trace_nfsd_set_fh_dentry_badhandle(rqstp, fhp, 246 dentry ? PTR_ERR(dentry) : -ESTALE); 247 switch (PTR_ERR(dentry)) { 248 case -ENOMEM: 249 case -ETIMEDOUT: 250 break; 251 default: 252 dentry = ERR_PTR(-ESTALE); 253 } 254 } 255 } 256 if (dentry == NULL) 257 goto out; 258 if (IS_ERR(dentry)) { 259 if (PTR_ERR(dentry) != -EINVAL) 260 error = nfserrno(PTR_ERR(dentry)); 261 goto out; 262 } 263 264 if (d_is_dir(dentry) && 265 (dentry->d_flags & DCACHE_DISCONNECTED)) { 266 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n", 267 dentry); 268 } 269 270 fhp->fh_dentry = dentry; 271 fhp->fh_export = exp; 272 273 switch (fhp->fh_maxsize) { 274 case NFS4_FHSIZE: 275 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR) 276 fhp->fh_no_atomic_attr = true; 277 fhp->fh_64bit_cookies = true; 278 break; 279 case NFS3_FHSIZE: 280 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC) 281 fhp->fh_no_wcc = true; 282 fhp->fh_64bit_cookies = true; 283 if (exp->ex_flags & NFSEXP_V4ROOT) 284 goto out; 285 break; 286 case NFS_FHSIZE: 287 fhp->fh_no_wcc = true; 288 if (EX_WGATHER(exp)) 289 fhp->fh_use_wgather = true; 290 if (exp->ex_flags & NFSEXP_V4ROOT) 291 goto out; 292 } 293 294 return 0; 295 out: 296 exp_put(exp); 297 return error; 298 } 299 300 /** 301 * __fh_verify - filehandle lookup and access checking 302 * @rqstp: RPC transaction context, or NULL 303 * @net: net namespace in which to perform the export lookup 304 * @cred: RPC user credential 305 * @client: RPC auth domain 306 * @gssclient: RPC GSS auth domain, or NULL 307 * @fhp: filehandle to be verified 308 * @type: expected type of object pointed to by filehandle 309 * @access: type of access needed to object 310 * 311 * See fh_verify() for further descriptions of @fhp, @type, and @access. 312 */ 313 static __be32 314 __fh_verify(struct svc_rqst *rqstp, 315 struct net *net, struct svc_cred *cred, 316 struct auth_domain *client, 317 struct auth_domain *gssclient, 318 struct svc_fh *fhp, umode_t type, int access) 319 { 320 struct nfsd_net *nn = net_generic(net, nfsd_net_id); 321 struct svc_export *exp = NULL; 322 bool may_bypass_gss = false; 323 struct dentry *dentry; 324 __be32 error; 325 326 if (!fhp->fh_dentry) { 327 error = nfsd_set_fh_dentry(rqstp, net, cred, client, 328 gssclient, fhp); 329 if (error) 330 goto out; 331 } 332 dentry = fhp->fh_dentry; 333 exp = fhp->fh_export; 334 335 trace_nfsd_fh_verify(rqstp, fhp, type, access); 336 337 /* 338 * We still have to do all these permission checks, even when 339 * fh_dentry is already set: 340 * - fh_verify may be called multiple times with different 341 * "access" arguments (e.g. nfsd_proc_create calls 342 * fh_verify(...,NFSD_MAY_EXEC) first, then later (in 343 * nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE). 344 * - in the NFSv4 case, the filehandle may have been filled 345 * in by fh_compose, and given a dentry, but further 346 * compound operations performed with that filehandle 347 * still need permissions checks. In the worst case, a 348 * mountpoint crossing may have changed the export 349 * options, and we may now need to use a different uid 350 * (for example, if different id-squashing options are in 351 * effect on the new filesystem). 352 */ 353 error = check_pseudo_root(dentry, exp); 354 if (error) 355 goto out; 356 357 error = nfsd_setuser_and_check_port(rqstp, cred, exp); 358 if (error) 359 goto out; 360 361 error = nfsd_mode_check(dentry, type); 362 if (error) 363 goto out; 364 365 if ((access & NFSD_MAY_NLM) && (exp->ex_flags & NFSEXP_NOAUTHNLM)) 366 /* NLM is allowed to fully bypass authentication */ 367 goto out; 368 369 if (access & NFSD_MAY_BYPASS_GSS) 370 may_bypass_gss = true; 371 /* 372 * Clients may expect to be able to use auth_sys during mount, 373 * even if they use gss for everything else; see section 2.3.2 374 * of rfc 2623. 375 */ 376 if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT 377 && exp->ex_path.dentry == dentry) 378 may_bypass_gss = true; 379 380 error = check_nfsd_access(exp, rqstp, may_bypass_gss); 381 if (error) 382 goto out; 383 /* During LOCALIO call to fh_verify will be called with a NULL rqstp */ 384 if (rqstp) 385 svc_xprt_set_valid(rqstp->rq_xprt); 386 387 /* Finally, check access permissions. */ 388 error = nfsd_permission(cred, exp, dentry, access); 389 out: 390 trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error); 391 if (error == nfserr_stale) 392 nfsd_stats_fh_stale_inc(nn, exp); 393 return error; 394 } 395 396 /** 397 * fh_verify_local - filehandle lookup and access checking 398 * @net: net namespace in which to perform the export lookup 399 * @cred: RPC user credential 400 * @client: RPC auth domain 401 * @fhp: filehandle to be verified 402 * @type: expected type of object pointed to by filehandle 403 * @access: type of access needed to object 404 * 405 * This API can be used by callers who do not have an RPC 406 * transaction context (ie are not running in an nfsd thread). 407 * 408 * See fh_verify() for further descriptions of @fhp, @type, and @access. 409 */ 410 __be32 411 fh_verify_local(struct net *net, struct svc_cred *cred, 412 struct auth_domain *client, struct svc_fh *fhp, 413 umode_t type, int access) 414 { 415 return __fh_verify(NULL, net, cred, client, NULL, 416 fhp, type, access); 417 } 418 419 /** 420 * fh_verify - filehandle lookup and access checking 421 * @rqstp: pointer to current rpc request 422 * @fhp: filehandle to be verified 423 * @type: expected type of object pointed to by filehandle 424 * @access: type of access needed to object 425 * 426 * Look up a dentry from the on-the-wire filehandle, check the client's 427 * access to the export, and set the current task's credentials. 428 * 429 * Regardless of success or failure of fh_verify(), fh_put() should be 430 * called on @fhp when the caller is finished with the filehandle. 431 * 432 * fh_verify() may be called multiple times on a given filehandle, for 433 * example, when processing an NFSv4 compound. The first call will look 434 * up a dentry using the on-the-wire filehandle. Subsequent calls will 435 * skip the lookup and just perform the other checks and possibly change 436 * the current task's credentials. 437 * 438 * @type specifies the type of object expected using one of the S_IF* 439 * constants defined in include/linux/stat.h. The caller may use zero 440 * to indicate that it doesn't care, or a negative integer to indicate 441 * that it expects something not of the given type. 442 * 443 * @access is formed from the NFSD_MAY_* constants defined in 444 * fs/nfsd/vfs.h. 445 */ 446 __be32 447 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) 448 { 449 return __fh_verify(rqstp, SVC_NET(rqstp), &rqstp->rq_cred, 450 rqstp->rq_client, rqstp->rq_gssclient, 451 fhp, type, access); 452 } 453 454 /* 455 * Compose a file handle for an NFS reply. 456 * 457 * Note that when first composed, the dentry may not yet have 458 * an inode. In this case a call to fh_update should be made 459 * before the fh goes out on the wire ... 460 */ 461 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp, 462 struct dentry *dentry) 463 { 464 if (dentry != exp->ex_path.dentry) { 465 struct fid *fid = (struct fid *) 466 (fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1); 467 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4; 468 int fh_flags = (exp->ex_flags & NFSEXP_NOSUBTREECHECK) ? 0 : 469 EXPORT_FH_CONNECTABLE; 470 int fileid_type = 471 exportfs_encode_fh(dentry, fid, &maxsize, fh_flags); 472 473 fhp->fh_handle.fh_fileid_type = 474 fileid_type > 0 ? fileid_type : FILEID_INVALID; 475 fhp->fh_handle.fh_size += maxsize * 4; 476 } else { 477 fhp->fh_handle.fh_fileid_type = FILEID_ROOT; 478 } 479 } 480 481 static bool is_root_export(struct svc_export *exp) 482 { 483 return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root; 484 } 485 486 static struct super_block *exp_sb(struct svc_export *exp) 487 { 488 return exp->ex_path.dentry->d_sb; 489 } 490 491 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp) 492 { 493 switch (fsid_type) { 494 case FSID_DEV: 495 if (!old_valid_dev(exp_sb(exp)->s_dev)) 496 return false; 497 fallthrough; 498 case FSID_MAJOR_MINOR: 499 case FSID_ENCODE_DEV: 500 return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV; 501 case FSID_NUM: 502 return exp->ex_flags & NFSEXP_FSID; 503 case FSID_UUID8: 504 case FSID_UUID16: 505 if (!is_root_export(exp)) 506 return false; 507 fallthrough; 508 case FSID_UUID4_INUM: 509 case FSID_UUID16_INUM: 510 return exp->ex_uuid != NULL; 511 } 512 return true; 513 } 514 515 516 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh) 517 { 518 u8 version; 519 u8 fsid_type; 520 retry: 521 version = 1; 522 if (ref_fh && ref_fh->fh_export == exp) { 523 version = ref_fh->fh_handle.fh_version; 524 fsid_type = ref_fh->fh_handle.fh_fsid_type; 525 526 ref_fh = NULL; 527 528 switch (version) { 529 case 0xca: 530 fsid_type = FSID_DEV; 531 break; 532 case 1: 533 break; 534 default: 535 goto retry; 536 } 537 538 /* 539 * As the fsid -> filesystem mapping was guided by 540 * user-space, there is no guarantee that the filesystem 541 * actually supports that fsid type. If it doesn't we 542 * loop around again without ref_fh set. 543 */ 544 if (!fsid_type_ok_for_exp(fsid_type, exp)) 545 goto retry; 546 } else if (exp->ex_flags & NFSEXP_FSID) { 547 fsid_type = FSID_NUM; 548 } else if (exp->ex_uuid) { 549 if (fhp->fh_maxsize >= 64) { 550 if (is_root_export(exp)) 551 fsid_type = FSID_UUID16; 552 else 553 fsid_type = FSID_UUID16_INUM; 554 } else { 555 if (is_root_export(exp)) 556 fsid_type = FSID_UUID8; 557 else 558 fsid_type = FSID_UUID4_INUM; 559 } 560 } else if (!old_valid_dev(exp_sb(exp)->s_dev)) 561 /* for newer device numbers, we must use a newer fsid format */ 562 fsid_type = FSID_ENCODE_DEV; 563 else 564 fsid_type = FSID_DEV; 565 fhp->fh_handle.fh_version = version; 566 if (version) 567 fhp->fh_handle.fh_fsid_type = fsid_type; 568 } 569 570 __be32 571 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry, 572 struct svc_fh *ref_fh) 573 { 574 /* ref_fh is a reference file handle. 575 * if it is non-null and for the same filesystem, then we should compose 576 * a filehandle which is of the same version, where possible. 577 */ 578 579 struct inode * inode = d_inode(dentry); 580 dev_t ex_dev = exp_sb(exp)->s_dev; 581 582 dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n", 583 MAJOR(ex_dev), MINOR(ex_dev), 584 (long) d_inode(exp->ex_path.dentry)->i_ino, 585 dentry, 586 (inode ? inode->i_ino : 0)); 587 588 /* Choose filehandle version and fsid type based on 589 * the reference filehandle (if it is in the same export) 590 * or the export options. 591 */ 592 set_version_and_fsid_type(fhp, exp, ref_fh); 593 594 /* If we have a ref_fh, then copy the fh_no_wcc setting from it. */ 595 fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false; 596 597 if (ref_fh == fhp) 598 fh_put(ref_fh); 599 600 if (fhp->fh_dentry) { 601 printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n", 602 dentry); 603 } 604 if (fhp->fh_maxsize < NFS_FHSIZE) 605 printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n", 606 fhp->fh_maxsize, 607 dentry); 608 609 fhp->fh_dentry = dget(dentry); /* our internal copy */ 610 fhp->fh_export = exp_get(exp); 611 612 fhp->fh_handle.fh_size = 613 key_len(fhp->fh_handle.fh_fsid_type) + 4; 614 fhp->fh_handle.fh_auth_type = 0; 615 616 mk_fsid(fhp->fh_handle.fh_fsid_type, 617 fhp->fh_handle.fh_fsid, 618 ex_dev, 619 d_inode(exp->ex_path.dentry)->i_ino, 620 exp->ex_fsid, exp->ex_uuid); 621 622 if (inode) 623 _fh_update(fhp, exp, dentry); 624 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) { 625 fh_put(fhp); 626 return nfserr_stale; 627 } 628 629 return 0; 630 } 631 632 /* 633 * Update file handle information after changing a dentry. 634 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create 635 */ 636 __be32 637 fh_update(struct svc_fh *fhp) 638 { 639 struct dentry *dentry; 640 641 if (!fhp->fh_dentry) 642 goto out_bad; 643 644 dentry = fhp->fh_dentry; 645 if (d_really_is_negative(dentry)) 646 goto out_negative; 647 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT) 648 return 0; 649 650 _fh_update(fhp, fhp->fh_export, dentry); 651 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) 652 return nfserr_stale; 653 return 0; 654 out_bad: 655 printk(KERN_ERR "fh_update: fh not verified!\n"); 656 return nfserr_serverfault; 657 out_negative: 658 printk(KERN_ERR "fh_update: %pd2 still negative!\n", 659 dentry); 660 return nfserr_serverfault; 661 } 662 663 /** 664 * fh_fill_pre_attrs - Fill in pre-op attributes 665 * @fhp: file handle to be updated 666 * 667 */ 668 __be32 __must_check fh_fill_pre_attrs(struct svc_fh *fhp) 669 { 670 bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE); 671 struct kstat stat; 672 __be32 err; 673 674 if (fhp->fh_no_wcc || fhp->fh_pre_saved) 675 return nfs_ok; 676 677 err = fh_getattr(fhp, &stat); 678 if (err) 679 return err; 680 681 if (v4) 682 fhp->fh_pre_change = nfsd4_change_attribute(&stat); 683 684 fhp->fh_pre_mtime = stat.mtime; 685 fhp->fh_pre_ctime = stat.ctime; 686 fhp->fh_pre_size = stat.size; 687 fhp->fh_pre_saved = true; 688 return nfs_ok; 689 } 690 691 /** 692 * fh_fill_post_attrs - Fill in post-op attributes 693 * @fhp: file handle to be updated 694 * 695 */ 696 __be32 fh_fill_post_attrs(struct svc_fh *fhp) 697 { 698 bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE); 699 __be32 err; 700 701 if (fhp->fh_no_wcc) 702 return nfs_ok; 703 704 if (fhp->fh_post_saved) 705 printk("nfsd: inode locked twice during operation.\n"); 706 707 err = fh_getattr(fhp, &fhp->fh_post_attr); 708 if (err) 709 return err; 710 711 fhp->fh_post_saved = true; 712 if (v4) 713 fhp->fh_post_change = 714 nfsd4_change_attribute(&fhp->fh_post_attr); 715 return nfs_ok; 716 } 717 718 /** 719 * fh_fill_both_attrs - Fill pre-op and post-op attributes 720 * @fhp: file handle to be updated 721 * 722 * This is used when the directory wasn't changed, but wcc attributes 723 * are needed anyway. 724 */ 725 __be32 __must_check fh_fill_both_attrs(struct svc_fh *fhp) 726 { 727 __be32 err; 728 729 err = fh_fill_post_attrs(fhp); 730 if (err) 731 return err; 732 733 fhp->fh_pre_change = fhp->fh_post_change; 734 fhp->fh_pre_mtime = fhp->fh_post_attr.mtime; 735 fhp->fh_pre_ctime = fhp->fh_post_attr.ctime; 736 fhp->fh_pre_size = fhp->fh_post_attr.size; 737 fhp->fh_pre_saved = true; 738 return nfs_ok; 739 } 740 741 /* 742 * Release a file handle. 743 */ 744 void 745 fh_put(struct svc_fh *fhp) 746 { 747 struct dentry * dentry = fhp->fh_dentry; 748 struct svc_export * exp = fhp->fh_export; 749 if (dentry) { 750 fhp->fh_dentry = NULL; 751 dput(dentry); 752 fh_clear_pre_post_attrs(fhp); 753 } 754 fh_drop_write(fhp); 755 if (exp) { 756 exp_put(exp); 757 fhp->fh_export = NULL; 758 } 759 fhp->fh_no_wcc = false; 760 return; 761 } 762 763 /* 764 * Shorthand for dprintk()'s 765 */ 766 char * SVCFH_fmt(struct svc_fh *fhp) 767 { 768 struct knfsd_fh *fh = &fhp->fh_handle; 769 static char buf[2+1+1+64*3+1]; 770 771 if (fh->fh_size > 64) 772 return "bad-fh"; 773 sprintf(buf, "%d: %*ph", fh->fh_size, fh->fh_size, fh->fh_raw); 774 return buf; 775 } 776 777 enum fsid_source fsid_source(const struct svc_fh *fhp) 778 { 779 if (fhp->fh_handle.fh_version != 1) 780 return FSIDSOURCE_DEV; 781 switch(fhp->fh_handle.fh_fsid_type) { 782 case FSID_DEV: 783 case FSID_ENCODE_DEV: 784 case FSID_MAJOR_MINOR: 785 if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV) 786 return FSIDSOURCE_DEV; 787 break; 788 case FSID_NUM: 789 if (fhp->fh_export->ex_flags & NFSEXP_FSID) 790 return FSIDSOURCE_FSID; 791 break; 792 default: 793 break; 794 } 795 /* either a UUID type filehandle, or the filehandle doesn't 796 * match the export. 797 */ 798 if (fhp->fh_export->ex_flags & NFSEXP_FSID) 799 return FSIDSOURCE_FSID; 800 if (fhp->fh_export->ex_uuid) 801 return FSIDSOURCE_UUID; 802 return FSIDSOURCE_DEV; 803 } 804 805 /** 806 * nfsd4_change_attribute - Generate an NFSv4 change_attribute value 807 * @stat: inode attributes 808 * 809 * Caller must fill in @stat before calling, typically by invoking 810 * vfs_getattr() with STATX_MODE, STATX_CTIME, and STATX_CHANGE_COOKIE. 811 * Returns an unsigned 64-bit changeid4 value (RFC 8881 Section 3.2). 812 * 813 * We could use i_version alone as the change attribute. However, i_version 814 * can go backwards on a regular file after an unclean shutdown. On its own 815 * that doesn't necessarily cause a problem, but if i_version goes backwards 816 * and then is incremented again it could reuse a value that was previously 817 * used before boot, and a client who queried the two values might incorrectly 818 * assume nothing changed. 819 * 820 * By using both ctime and the i_version counter we guarantee that as long as 821 * time doesn't go backwards we never reuse an old value. If the filesystem 822 * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not 823 * needed. 824 * 825 * We only need to do this for regular files as well. For directories, we 826 * assume that the new change attr is always logged to stable storage in some 827 * fashion before the results can be seen. 828 */ 829 u64 nfsd4_change_attribute(const struct kstat *stat) 830 { 831 u64 chattr; 832 833 if (stat->result_mask & STATX_CHANGE_COOKIE) { 834 chattr = stat->change_cookie; 835 if (S_ISREG(stat->mode) && 836 !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) { 837 chattr += (u64)stat->ctime.tv_sec << 30; 838 chattr += stat->ctime.tv_nsec; 839 } 840 } else { 841 chattr = time_to_chattr(&stat->ctime); 842 } 843 return chattr; 844 } 845