1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1994, 1995 The Regents of the University of California. 5 * Copyright (c) 1994, 1995 Jan-Simon Pendry. 6 * Copyright (c) 2005, 2006, 2012 Masanori Ozawa <ozawa@ongs.co.jp>, ONGS Inc. 7 * Copyright (c) 2006, 2012 Daichi Goto <daichi@freebsd.org> 8 * All rights reserved. 9 * 10 * This code is derived from software donated to Berkeley by 11 * Jan-Simon Pendry. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38#include <sys/param.h> 39#include <sys/systm.h> 40#include <sys/kdb.h> 41#include <sys/fcntl.h> 42#include <sys/kernel.h> 43#include <sys/lock.h> 44#include <sys/malloc.h> 45#include <sys/mount.h> 46#include <sys/namei.h> 47#include <sys/proc.h> 48#include <sys/vnode.h> 49#include <sys/stat.h> 50 51#include <fs/unionfs/union.h> 52 53static MALLOC_DEFINE(M_UNIONFSMNT, "UNIONFS mount", "UNIONFS mount structure"); 54 55static vfs_fhtovp_t unionfs_fhtovp; 56static vfs_checkexp_t unionfs_checkexp; 57static vfs_mount_t unionfs_domount; 58static vfs_quotactl_t unionfs_quotactl; 59static vfs_root_t unionfs_root; 60static vfs_sync_t unionfs_sync; 61static vfs_statfs_t unionfs_statfs; 62static vfs_unmount_t unionfs_unmount; 63static vfs_vget_t unionfs_vget; 64static vfs_extattrctl_t unionfs_extattrctl; 65 66static struct vfsops unionfs_vfsops; 67 68/* 69 * Mount unionfs layer. 70 */ 71static int 72unionfs_domount(struct mount *mp) 73{ 74 struct vnode *lowerrootvp; 75 struct vnode *upperrootvp; 76 struct unionfs_mount *ump; 77 char *target; 78 char *tmp; 79 char *ep; 80 struct nameidata nd, *ndp; 81 struct vattr va; 82 unionfs_copymode copymode; 83 unionfs_whitemode whitemode; 84 int below; 85 int error; 86 int len; 87 uid_t uid; 88 gid_t gid; 89 u_short udir; 90 u_short ufile; 91 92 UNIONFSDEBUG("unionfs_mount(mp = %p)\n", mp); 93 94 error = 0; 95 below = 0; 96 uid = 0; 97 gid = 0; 98 udir = 0; 99 ufile = 0; 100 copymode = UNIONFS_TRANSPARENT; /* default */ 101 whitemode = UNIONFS_WHITE_ALWAYS; 102 ndp = &nd; 103 104 if (mp->mnt_flag & MNT_ROOTFS) { 105 vfs_mount_error(mp, "Cannot union mount root filesystem"); 106 return (EOPNOTSUPP); 107 } 108 109 /* 110 * Update is a no operation. 111 */ 112 if (mp->mnt_flag & MNT_UPDATE) { 113 vfs_mount_error(mp, "unionfs does not support mount update"); 114 return (EOPNOTSUPP); 115 } 116 117 /* 118 * Get argument 119 */ 120 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 121 if (error) 122 error = vfs_getopt(mp->mnt_optnew, "from", (void **)&target, 123 &len); 124 if (error || target[len - 1] != '\0') { 125 vfs_mount_error(mp, "Invalid target"); 126 return (EINVAL); 127 } 128 if (vfs_getopt(mp->mnt_optnew, "below", NULL, NULL) == 0) 129 below = 1; 130 if (vfs_getopt(mp->mnt_optnew, "udir", (void **)&tmp, NULL) == 0) { 131 if (tmp != NULL) 132 udir = (mode_t)strtol(tmp, &ep, 8); 133 if (tmp == NULL || *ep) { 134 vfs_mount_error(mp, "Invalid udir"); 135 return (EINVAL); 136 } 137 udir &= S_IRWXU | S_IRWXG | S_IRWXO; 138 } 139 if (vfs_getopt(mp->mnt_optnew, "ufile", (void **)&tmp, NULL) == 0) { 140 if (tmp != NULL) 141 ufile = (mode_t)strtol(tmp, &ep, 8); 142 if (tmp == NULL || *ep) { 143 vfs_mount_error(mp, "Invalid ufile"); 144 return (EINVAL); 145 } 146 ufile &= S_IRWXU | S_IRWXG | S_IRWXO; 147 } 148 /* check umask, uid and gid */ 149 if (udir == 0 && ufile != 0) 150 udir = ufile; 151 if (ufile == 0 && udir != 0) 152 ufile = udir; 153 154 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY); 155 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred); 156 if (!error) { 157 if (udir == 0) 158 udir = va.va_mode; 159 if (ufile == 0) 160 ufile = va.va_mode; 161 uid = va.va_uid; 162 gid = va.va_gid; 163 } 164 VOP_UNLOCK(mp->mnt_vnodecovered); 165 if (error) 166 return (error); 167 168 if (mp->mnt_cred->cr_ruid == 0) { /* root only */ 169 if (vfs_getopt(mp->mnt_optnew, "uid", (void **)&tmp, 170 NULL) == 0) { 171 if (tmp != NULL) 172 uid = (uid_t)strtol(tmp, &ep, 10); 173 if (tmp == NULL || *ep) { 174 vfs_mount_error(mp, "Invalid uid"); 175 return (EINVAL); 176 } 177 } 178 if (vfs_getopt(mp->mnt_optnew, "gid", (void **)&tmp, 179 NULL) == 0) { 180 if (tmp != NULL) 181 gid = (gid_t)strtol(tmp, &ep, 10); 182 if (tmp == NULL || *ep) { 183 vfs_mount_error(mp, "Invalid gid"); 184 return (EINVAL); 185 } 186 } 187 if (vfs_getopt(mp->mnt_optnew, "copymode", (void **)&tmp, 188 NULL) == 0) { 189 if (tmp == NULL) { 190 vfs_mount_error(mp, "Invalid copymode"); 191 return (EINVAL); 192 } else if (strcasecmp(tmp, "traditional") == 0) 193 copymode = UNIONFS_TRADITIONAL; 194 else if (strcasecmp(tmp, "transparent") == 0) 195 copymode = UNIONFS_TRANSPARENT; 196 else if (strcasecmp(tmp, "masquerade") == 0) 197 copymode = UNIONFS_MASQUERADE; 198 else { 199 vfs_mount_error(mp, "Invalid copymode"); 200 return (EINVAL); 201 } 202 } 203 if (vfs_getopt(mp->mnt_optnew, "whiteout", (void **)&tmp, 204 NULL) == 0) { 205 if (tmp == NULL) { 206 vfs_mount_error(mp, "Invalid whiteout mode"); 207 return (EINVAL); 208 } else if (strcasecmp(tmp, "always") == 0) 209 whitemode = UNIONFS_WHITE_ALWAYS; 210 else if (strcasecmp(tmp, "whenneeded") == 0) 211 whitemode = UNIONFS_WHITE_WHENNEEDED; 212 else { 213 vfs_mount_error(mp, "Invalid whiteout mode"); 214 return (EINVAL); 215 } 216 } 217 } 218 /* If copymode is UNIONFS_TRADITIONAL, uid/gid is mounted user. */ 219 if (copymode == UNIONFS_TRADITIONAL) { 220 uid = mp->mnt_cred->cr_ruid; 221 gid = mp->mnt_cred->cr_rgid; 222 } 223 224 UNIONFSDEBUG("unionfs_mount: uid=%d, gid=%d\n", uid, gid); 225 UNIONFSDEBUG("unionfs_mount: udir=0%03o, ufile=0%03o\n", udir, ufile); 226 UNIONFSDEBUG("unionfs_mount: copymode=%d\n", copymode); 227 228 /* 229 * Find upper node 230 */ 231 NDINIT(ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, target); 232 if ((error = namei(ndp))) 233 return (error); 234 235 NDFREE_PNBUF(ndp); 236 237 /* get root vnodes */ 238 lowerrootvp = mp->mnt_vnodecovered; 239 upperrootvp = ndp->ni_vp; 240 KASSERT(lowerrootvp != NULL, ("%s: NULL lower root vp", __func__)); 241 KASSERT(upperrootvp != NULL, ("%s: NULL upper root vp", __func__)); 242 243 /* create unionfs_mount */ 244 ump = malloc(sizeof(struct unionfs_mount), M_UNIONFSMNT, 245 M_WAITOK | M_ZERO); 246 247 /* 248 * Save reference 249 */ 250 if (below) { 251 VOP_UNLOCK(upperrootvp); 252 vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY); 253 ump->um_lowervp = upperrootvp; 254 ump->um_uppervp = lowerrootvp; 255 } else { 256 ump->um_lowervp = lowerrootvp; 257 ump->um_uppervp = upperrootvp; 258 } 259 ump->um_rootvp = NULLVP; 260 ump->um_uid = uid; 261 ump->um_gid = gid; 262 ump->um_udir = udir; 263 ump->um_ufile = ufile; 264 ump->um_copymode = copymode; 265 ump->um_whitemode = whitemode; 266 267 mp->mnt_data = ump; 268 269 /* 270 * Copy upper layer's RDONLY flag. 271 */ 272 mp->mnt_flag |= ump->um_uppervp->v_mount->mnt_flag & MNT_RDONLY; 273 274 /* 275 * Unlock the node 276 */ 277 VOP_UNLOCK(ump->um_uppervp); 278 279 /* 280 * Get the unionfs root vnode. 281 */ 282 error = unionfs_nodeget(mp, ump->um_uppervp, ump->um_lowervp, 283 NULLVP, &(ump->um_rootvp), NULL); 284 if (error != 0) { 285 vrele(upperrootvp); 286 free(ump, M_UNIONFSMNT); 287 mp->mnt_data = NULL; 288 return (error); 289 } 290 KASSERT(ump->um_rootvp != NULL, ("rootvp cannot be NULL")); 291 KASSERT((ump->um_rootvp->v_vflag & VV_ROOT) != 0, 292 ("%s: rootvp without VV_ROOT", __func__)); 293 294 /* 295 * Do not release the namei() reference on upperrootvp until after 296 * we attempt to register the upper mounts. A concurrent unmount 297 * of the upper or lower FS may have caused unionfs_nodeget() to 298 * create a unionfs node with a NULL upper or lower vp and with 299 * no reference held on upperrootvp or lowerrootvp. 300 * vfs_register_upper() should subsequently fail, which is what 301 * we want, but we must ensure neither underlying vnode can be 302 * reused until that happens. We assume the caller holds a reference 303 * to lowerrootvp as it is the mount's covered vnode. 304 */ 305 ump->um_lowermp = vfs_register_upper_from_vp(ump->um_lowervp, mp, 306 &ump->um_lower_link); 307 ump->um_uppermp = vfs_register_upper_from_vp(ump->um_uppervp, mp, 308 &ump->um_upper_link); 309 310 vrele(upperrootvp); 311 312 if (ump->um_lowermp == NULL || ump->um_uppermp == NULL) { 313 if (ump->um_lowermp != NULL) 314 vfs_unregister_upper(ump->um_lowermp, &ump->um_lower_link); 315 if (ump->um_uppermp != NULL) 316 vfs_unregister_upper(ump->um_uppermp, &ump->um_upper_link); 317 vflush(mp, 1, FORCECLOSE, curthread); 318 free(ump, M_UNIONFSMNT); 319 mp->mnt_data = NULL; 320 return (ENOENT); 321 } 322 323 /* 324 * Specify that the covered vnode lock should remain held while 325 * lookup() performs the cross-mount walk. This prevents a lock-order 326 * reversal between the covered vnode lock (which is also locked by 327 * unionfs_lock()) and the mountpoint's busy count. Without this, 328 * unmount will lock the covered vnode lock (directly through the 329 * covered vnode) and wait for the busy count to drain, while a 330 * concurrent lookup will increment the busy count and then lock 331 * the covered vnode lock (indirectly through unionfs_lock()). 332 * 333 * Note that we can't yet use this facility for the 'below' case 334 * in which the upper vnode is the covered vnode, because that would 335 * introduce a different LOR in which the cross-mount lookup would 336 * effectively hold the upper vnode lock before acquiring the lower 337 * vnode lock, while an unrelated lock operation would still acquire 338 * the lower vnode lock before the upper vnode lock, which is the 339 * order unionfs currently requires. 340 */ 341 if (!below) { 342 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE); 343 mp->mnt_vnodecovered->v_vflag |= VV_CROSSLOCK; 344 VOP_UNLOCK(mp->mnt_vnodecovered); 345 } 346 347 MNT_ILOCK(mp); 348 if ((ump->um_lowermp->mnt_flag & MNT_LOCAL) != 0 && 349 (ump->um_uppermp->mnt_flag & MNT_LOCAL) != 0) 350 mp->mnt_flag |= MNT_LOCAL; 351 mp->mnt_kern_flag |= MNTK_NOMSYNC | MNTK_UNIONFS | 352 (ump->um_uppermp->mnt_kern_flag & MNTK_SHARED_WRITES); 353 MNT_IUNLOCK(mp); 354 355 /* 356 * Get new fsid 357 */ 358 vfs_getnewfsid(mp); 359 360 snprintf(mp->mnt_stat.f_mntfromname, MNAMELEN, "<%s>:%s", 361 below ? "below" : "above", target); 362 363 UNIONFSDEBUG("unionfs_mount: from %s, on %s\n", 364 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 365 366 return (0); 367} 368 369/* 370 * Free reference to unionfs layer 371 */ 372static int 373unionfs_unmount(struct mount *mp, int mntflags) 374{ 375 struct unionfs_mount *ump; 376 int error; 377 int num; 378 int freeing; 379 int flags; 380 381 UNIONFSDEBUG("unionfs_unmount: mp = %p\n", mp); 382 383 ump = MOUNTTOUNIONFSMOUNT(mp); 384 flags = 0; 385 386 if (mntflags & MNT_FORCE) 387 flags |= FORCECLOSE; 388 389 /* vflush (no need to call vrele) */ 390 for (freeing = 0; (error = vflush(mp, 1, flags, curthread)) != 0;) { 391 num = mp->mnt_nvnodelistsize; 392 if (num == freeing) 393 break; 394 freeing = num; 395 } 396 397 if (error) 398 return (error); 399 400 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE); 401 mp->mnt_vnodecovered->v_vflag &= ~VV_CROSSLOCK; 402 VOP_UNLOCK(mp->mnt_vnodecovered); 403 vfs_unregister_upper(ump->um_lowermp, &ump->um_lower_link); 404 vfs_unregister_upper(ump->um_uppermp, &ump->um_upper_link); 405 free(ump, M_UNIONFSMNT); 406 mp->mnt_data = NULL; 407 408 return (0); 409} 410 411static int 412unionfs_root(struct mount *mp, int flags, struct vnode **vpp) 413{ 414 struct unionfs_mount *ump; 415 struct vnode *vp; 416 417 ump = MOUNTTOUNIONFSMOUNT(mp); 418 vp = ump->um_rootvp; 419 420 UNIONFSDEBUG("unionfs_root: rootvp=%p locked=%x\n", 421 vp, VOP_ISLOCKED(vp)); 422 423 vref(vp); 424 if (flags & LK_TYPE_MASK) 425 vn_lock(vp, flags); 426 427 *vpp = vp; 428 429 return (0); 430} 431 432static int 433unionfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg, 434 bool *mp_busy) 435{ 436 struct mount *uppermp; 437 struct unionfs_mount *ump; 438 int error; 439 bool unbusy; 440 441 ump = MOUNTTOUNIONFSMOUNT(mp); 442 /* 443 * Issue a volatile load of um_uppermp here, as the mount may be 444 * torn down after we call vfs_unbusy(). 445 */ 446 uppermp = atomic_load_ptr(&ump->um_uppermp); 447 KASSERT(*mp_busy == true, ("upper mount not busy")); 448 /* 449 * See comment in sys_quotactl() for an explanation of why the 450 * lower mount needs to be busied by the caller of VFS_QUOTACTL() 451 * but may be unbusied by the implementation. We must unbusy 452 * the upper mount for the same reason; otherwise a namei lookup 453 * issued by the VFS_QUOTACTL() implementation could traverse the 454 * upper mount and deadlock. 455 */ 456 vfs_unbusy(mp); 457 *mp_busy = false; 458 unbusy = true; 459 error = vfs_busy(uppermp, 0); 460 /* 461 * Writing is always performed to upper vnode. 462 */ 463 if (error == 0) 464 error = VFS_QUOTACTL(uppermp, cmd, uid, arg, &unbusy); 465 if (unbusy) 466 vfs_unbusy(uppermp); 467 468 return (error); 469} 470 471static int 472unionfs_statfs(struct mount *mp, struct statfs *sbp) 473{ 474 struct unionfs_mount *ump; 475 struct statfs *mstat; 476 uint64_t lbsize; 477 int error; 478 479 ump = MOUNTTOUNIONFSMOUNT(mp); 480 481 UNIONFSDEBUG("unionfs_statfs(mp = %p, lvp = %p, uvp = %p)\n", 482 mp, ump->um_lowervp, ump->um_uppervp); 483 484 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 485 486 error = VFS_STATFS(ump->um_lowermp, mstat); 487 if (error) { 488 free(mstat, M_STATFS); 489 return (error); 490 } 491 492 /* now copy across the "interesting" information and fake the rest */ 493 sbp->f_blocks = mstat->f_blocks; 494 sbp->f_files = mstat->f_files; 495 496 lbsize = mstat->f_bsize; 497 498 error = VFS_STATFS(ump->um_uppermp, mstat); 499 if (error) { 500 free(mstat, M_STATFS); 501 return (error); 502 } 503 504 /* 505 * The FS type etc is copy from upper vfs. 506 * (write able vfs have priority) 507 */ 508 sbp->f_type = mstat->f_type; 509 sbp->f_flags = mstat->f_flags; 510 sbp->f_bsize = mstat->f_bsize; 511 sbp->f_iosize = mstat->f_iosize; 512 513 if (mstat->f_bsize != lbsize) 514 sbp->f_blocks = ((off_t)sbp->f_blocks * lbsize) / 515 mstat->f_bsize; 516 517 sbp->f_blocks += mstat->f_blocks; 518 sbp->f_bfree = mstat->f_bfree; 519 sbp->f_bavail = mstat->f_bavail; 520 sbp->f_files += mstat->f_files; 521 sbp->f_ffree = mstat->f_ffree; 522 523 free(mstat, M_STATFS); 524 return (0); 525} 526 527static int 528unionfs_sync(struct mount *mp, int waitfor) 529{ 530 /* nothing to do */ 531 return (0); 532} 533 534static int 535unionfs_vget(struct mount *mp, ino_t ino, int flags, struct vnode **vpp) 536{ 537 return (EOPNOTSUPP); 538} 539 540static int 541unionfs_fhtovp(struct mount *mp, struct fid *fidp, int flags, 542 struct vnode **vpp) 543{ 544 return (EOPNOTSUPP); 545} 546 547static int 548unionfs_checkexp(struct mount *mp, struct sockaddr *nam, uint64_t *extflagsp, 549 struct ucred **credanonp, int *numsecflavors, int *secflavors) 550{ 551 return (EOPNOTSUPP); 552} 553 554static int 555unionfs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp, 556 int namespace, const char *attrname) 557{ 558 struct unionfs_mount *ump; 559 struct unionfs_node *unp; 560 561 ump = MOUNTTOUNIONFSMOUNT(mp); 562 unp = VTOUNIONFS(filename_vp); 563 564 if (unp->un_uppervp != NULLVP) { 565 return (VFS_EXTATTRCTL(ump->um_uppermp, cmd, 566 unp->un_uppervp, namespace, attrname)); 567 } else { 568 return (VFS_EXTATTRCTL(ump->um_lowermp, cmd, 569 unp->un_lowervp, namespace, attrname)); 570 } 571} 572 573static struct vfsops unionfs_vfsops = { 574 .vfs_checkexp = unionfs_checkexp, 575 .vfs_extattrctl = unionfs_extattrctl, 576 .vfs_fhtovp = unionfs_fhtovp, 577 .vfs_init = unionfs_init, 578 .vfs_mount = unionfs_domount, 579 .vfs_quotactl = unionfs_quotactl, 580 .vfs_root = unionfs_root, 581 .vfs_statfs = unionfs_statfs, 582 .vfs_sync = unionfs_sync, 583 .vfs_uninit = unionfs_uninit, 584 .vfs_unmount = unionfs_unmount, 585 .vfs_vget = unionfs_vget, 586}; 587 588VFS_SET(unionfs_vfsops, unionfs, VFCF_LOOPBACK); 589