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