/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1994, 1995 The Regents of the University of California. * Copyright (c) 1994, 1995 Jan-Simon Pendry. * Copyright (c) 2005, 2006, 2012 Masanori Ozawa , ONGS Inc. * Copyright (c) 2006, 2012 Daichi Goto * All rights reserved. * * This code is derived from software donated to Berkeley by * Jan-Simon Pendry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_UNIONFSMNT, "UNIONFS mount", "UNIONFS mount structure"); static vfs_fhtovp_t unionfs_fhtovp; static vfs_checkexp_t unionfs_checkexp; static vfs_mount_t unionfs_domount; static vfs_quotactl_t unionfs_quotactl; static vfs_root_t unionfs_root; static vfs_sync_t unionfs_sync; static vfs_statfs_t unionfs_statfs; static vfs_unmount_t unionfs_unmount; static vfs_vget_t unionfs_vget; static vfs_extattrctl_t unionfs_extattrctl; static struct vfsops unionfs_vfsops; /* * Mount unionfs layer. */ static int unionfs_domount(struct mount *mp) { struct vnode *lowerrootvp; struct vnode *upperrootvp; struct unionfs_mount *ump; char *target; char *tmp; char *ep; struct nameidata nd, *ndp; struct vattr va; unionfs_copymode copymode; unionfs_whitemode whitemode; int below; int error; int len; uid_t uid; gid_t gid; u_short udir; u_short ufile; UNIONFSDEBUG("unionfs_mount(mp = %p)\n", mp); error = 0; below = 0; uid = 0; gid = 0; udir = 0; ufile = 0; copymode = UNIONFS_TRANSPARENT; /* default */ whitemode = UNIONFS_WHITE_ALWAYS; ndp = &nd; if (mp->mnt_flag & MNT_ROOTFS) { vfs_mount_error(mp, "Cannot union mount root filesystem"); return (EOPNOTSUPP); } /* * Update is a no operation. */ if (mp->mnt_flag & MNT_UPDATE) { vfs_mount_error(mp, "unionfs does not support mount update"); return (EOPNOTSUPP); } /* * Get argument */ error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); if (error) error = vfs_getopt(mp->mnt_optnew, "from", (void **)&target, &len); if (error || target[len - 1] != '\0') { vfs_mount_error(mp, "Invalid target"); return (EINVAL); } if (vfs_getopt(mp->mnt_optnew, "below", NULL, NULL) == 0) below = 1; if (vfs_getopt(mp->mnt_optnew, "udir", (void **)&tmp, NULL) == 0) { if (tmp != NULL) udir = (mode_t)strtol(tmp, &ep, 8); if (tmp == NULL || *ep) { vfs_mount_error(mp, "Invalid udir"); return (EINVAL); } udir &= S_IRWXU | S_IRWXG | S_IRWXO; } if (vfs_getopt(mp->mnt_optnew, "ufile", (void **)&tmp, NULL) == 0) { if (tmp != NULL) ufile = (mode_t)strtol(tmp, &ep, 8); if (tmp == NULL || *ep) { vfs_mount_error(mp, "Invalid ufile"); return (EINVAL); } ufile &= S_IRWXU | S_IRWXG | S_IRWXO; } /* check umask, uid and gid */ if (udir == 0 && ufile != 0) udir = ufile; if (ufile == 0 && udir != 0) ufile = udir; vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY); error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred); if (!error) { if (udir == 0) udir = va.va_mode; if (ufile == 0) ufile = va.va_mode; uid = va.va_uid; gid = va.va_gid; } VOP_UNLOCK(mp->mnt_vnodecovered); if (error) return (error); if (mp->mnt_cred->cr_ruid == 0) { /* root only */ if (vfs_getopt(mp->mnt_optnew, "uid", (void **)&tmp, NULL) == 0) { if (tmp != NULL) uid = (uid_t)strtol(tmp, &ep, 10); if (tmp == NULL || *ep) { vfs_mount_error(mp, "Invalid uid"); return (EINVAL); } } if (vfs_getopt(mp->mnt_optnew, "gid", (void **)&tmp, NULL) == 0) { if (tmp != NULL) gid = (gid_t)strtol(tmp, &ep, 10); if (tmp == NULL || *ep) { vfs_mount_error(mp, "Invalid gid"); return (EINVAL); } } if (vfs_getopt(mp->mnt_optnew, "copymode", (void **)&tmp, NULL) == 0) { if (tmp == NULL) { vfs_mount_error(mp, "Invalid copymode"); return (EINVAL); } else if (strcasecmp(tmp, "traditional") == 0) copymode = UNIONFS_TRADITIONAL; else if (strcasecmp(tmp, "transparent") == 0) copymode = UNIONFS_TRANSPARENT; else if (strcasecmp(tmp, "masquerade") == 0) copymode = UNIONFS_MASQUERADE; else { vfs_mount_error(mp, "Invalid copymode"); return (EINVAL); } } if (vfs_getopt(mp->mnt_optnew, "whiteout", (void **)&tmp, NULL) == 0) { if (tmp == NULL) { vfs_mount_error(mp, "Invalid whiteout mode"); return (EINVAL); } else if (strcasecmp(tmp, "always") == 0) whitemode = UNIONFS_WHITE_ALWAYS; else if (strcasecmp(tmp, "whenneeded") == 0) whitemode = UNIONFS_WHITE_WHENNEEDED; else { vfs_mount_error(mp, "Invalid whiteout mode"); return (EINVAL); } } } /* If copymode is UNIONFS_TRADITIONAL, uid/gid is mounted user. */ if (copymode == UNIONFS_TRADITIONAL) { uid = mp->mnt_cred->cr_ruid; gid = mp->mnt_cred->cr_rgid; } UNIONFSDEBUG("unionfs_mount: uid=%d, gid=%d\n", uid, gid); UNIONFSDEBUG("unionfs_mount: udir=0%03o, ufile=0%03o\n", udir, ufile); UNIONFSDEBUG("unionfs_mount: copymode=%d\n", copymode); /* * Find upper node */ NDINIT(ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, target); if ((error = namei(ndp))) return (error); NDFREE_PNBUF(ndp); /* get root vnodes */ lowerrootvp = mp->mnt_vnodecovered; upperrootvp = ndp->ni_vp; KASSERT(lowerrootvp != NULL, ("%s: NULL lower root vp", __func__)); KASSERT(upperrootvp != NULL, ("%s: NULL upper root vp", __func__)); /* create unionfs_mount */ ump = malloc(sizeof(struct unionfs_mount), M_UNIONFSMNT, M_WAITOK | M_ZERO); /* * Save reference */ if (below) { VOP_UNLOCK(upperrootvp); vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY); ump->um_lowervp = upperrootvp; ump->um_uppervp = lowerrootvp; } else { ump->um_lowervp = lowerrootvp; ump->um_uppervp = upperrootvp; } ump->um_rootvp = NULLVP; ump->um_uid = uid; ump->um_gid = gid; ump->um_udir = udir; ump->um_ufile = ufile; ump->um_copymode = copymode; ump->um_whitemode = whitemode; mp->mnt_data = ump; /* * Copy upper layer's RDONLY flag. */ mp->mnt_flag |= ump->um_uppervp->v_mount->mnt_flag & MNT_RDONLY; /* * Unlock the node */ VOP_UNLOCK(ump->um_uppervp); /* * Get the unionfs root vnode. */ error = unionfs_nodeget(mp, ump->um_uppervp, ump->um_lowervp, NULLVP, &(ump->um_rootvp), NULL); if (error != 0) { vrele(upperrootvp); free(ump, M_UNIONFSMNT); mp->mnt_data = NULL; return (error); } KASSERT(ump->um_rootvp != NULL, ("rootvp cannot be NULL")); KASSERT((ump->um_rootvp->v_vflag & VV_ROOT) != 0, ("%s: rootvp without VV_ROOT", __func__)); /* * Do not release the namei() reference on upperrootvp until after * we attempt to register the upper mounts. A concurrent unmount * of the upper or lower FS may have caused unionfs_nodeget() to * create a unionfs node with a NULL upper or lower vp and with * no reference held on upperrootvp or lowerrootvp. * vfs_register_upper() should subsequently fail, which is what * we want, but we must ensure neither underlying vnode can be * reused until that happens. We assume the caller holds a reference * to lowerrootvp as it is the mount's covered vnode. */ ump->um_lowermp = vfs_register_upper_from_vp(ump->um_lowervp, mp, &ump->um_lower_link); ump->um_uppermp = vfs_register_upper_from_vp(ump->um_uppervp, mp, &ump->um_upper_link); vrele(upperrootvp); if (ump->um_lowermp == NULL || ump->um_uppermp == NULL) { if (ump->um_lowermp != NULL) vfs_unregister_upper(ump->um_lowermp, &ump->um_lower_link); if (ump->um_uppermp != NULL) vfs_unregister_upper(ump->um_uppermp, &ump->um_upper_link); vflush(mp, 1, FORCECLOSE, curthread); free(ump, M_UNIONFSMNT); mp->mnt_data = NULL; return (ENOENT); } /* * Specify that the covered vnode lock should remain held while * lookup() performs the cross-mount walk. This prevents a lock-order * reversal between the covered vnode lock (which is also locked by * unionfs_lock()) and the mountpoint's busy count. Without this, * unmount will lock the covered vnode lock (directly through the * covered vnode) and wait for the busy count to drain, while a * concurrent lookup will increment the busy count and then may lock * the covered vnode lock (indirectly through unionfs_lock()). * * Note that this is only needed for the 'below' case in which the * upper vnode is also the covered vnode, because unionfs_lock() * only locks the upper vnode as long as both lower and upper vnodes * are present (which they will always be for the unionfs mount root). */ if (below) { vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE); mp->mnt_vnodecovered->v_vflag |= VV_CROSSLOCK; VOP_UNLOCK(mp->mnt_vnodecovered); } MNT_ILOCK(mp); if ((ump->um_lowermp->mnt_flag & MNT_LOCAL) != 0 && (ump->um_uppermp->mnt_flag & MNT_LOCAL) != 0) mp->mnt_flag |= MNT_LOCAL; mp->mnt_kern_flag |= MNTK_NOMSYNC | MNTK_UNIONFS | (ump->um_uppermp->mnt_kern_flag & MNTK_SHARED_WRITES); MNT_IUNLOCK(mp); /* * Get new fsid */ vfs_getnewfsid(mp); snprintf(mp->mnt_stat.f_mntfromname, MNAMELEN, "<%s>:%s", below ? "below" : "above", target); UNIONFSDEBUG("unionfs_mount: from %s, on %s\n", mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); return (0); } /* * Free reference to unionfs layer */ static int unionfs_unmount(struct mount *mp, int mntflags) { struct unionfs_mount *ump; int error; int num; int freeing; int flags; UNIONFSDEBUG("unionfs_unmount: mp = %p\n", mp); ump = MOUNTTOUNIONFSMOUNT(mp); flags = 0; if (mntflags & MNT_FORCE) flags |= FORCECLOSE; /* vflush (no need to call vrele) */ for (freeing = 0; (error = vflush(mp, 1, flags, curthread)) != 0;) { num = mp->mnt_nvnodelistsize; if (num == freeing) break; freeing = num; } if (error) return (error); vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE); mp->mnt_vnodecovered->v_vflag &= ~VV_CROSSLOCK; VOP_UNLOCK(mp->mnt_vnodecovered); vfs_unregister_upper(ump->um_lowermp, &ump->um_lower_link); vfs_unregister_upper(ump->um_uppermp, &ump->um_upper_link); free(ump, M_UNIONFSMNT); mp->mnt_data = NULL; return (0); } static int unionfs_root(struct mount *mp, int flags, struct vnode **vpp) { struct unionfs_mount *ump; struct vnode *vp; ump = MOUNTTOUNIONFSMOUNT(mp); vp = ump->um_rootvp; UNIONFSDEBUG("unionfs_root: rootvp=%p locked=%x\n", vp, VOP_ISLOCKED(vp)); vref(vp); if (flags & LK_TYPE_MASK) vn_lock(vp, flags); *vpp = vp; return (0); } static int unionfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg, bool *mp_busy) { struct mount *uppermp; struct unionfs_mount *ump; int error; bool unbusy; ump = MOUNTTOUNIONFSMOUNT(mp); /* * Issue a volatile load of um_uppermp here, as the mount may be * torn down after we call vfs_unbusy(). */ uppermp = atomic_load_ptr(&ump->um_uppermp); KASSERT(*mp_busy == true, ("upper mount not busy")); /* * See comment in sys_quotactl() for an explanation of why the * lower mount needs to be busied by the caller of VFS_QUOTACTL() * but may be unbusied by the implementation. We must unbusy * the upper mount for the same reason; otherwise a namei lookup * issued by the VFS_QUOTACTL() implementation could traverse the * upper mount and deadlock. */ vfs_unbusy(mp); *mp_busy = false; unbusy = true; error = vfs_busy(uppermp, 0); /* * Writing is always performed to upper vnode. */ if (error == 0) error = VFS_QUOTACTL(uppermp, cmd, uid, arg, &unbusy); if (unbusy) vfs_unbusy(uppermp); return (error); } static int unionfs_statfs(struct mount *mp, struct statfs *sbp) { struct unionfs_mount *ump; struct statfs *mstat; uint64_t lbsize; int error; ump = MOUNTTOUNIONFSMOUNT(mp); UNIONFSDEBUG("unionfs_statfs(mp = %p, lvp = %p, uvp = %p)\n", mp, ump->um_lowervp, ump->um_uppervp); mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); error = VFS_STATFS(ump->um_lowermp, mstat); if (error) { free(mstat, M_STATFS); return (error); } /* now copy across the "interesting" information and fake the rest */ sbp->f_blocks = mstat->f_blocks; sbp->f_files = mstat->f_files; lbsize = mstat->f_bsize; error = VFS_STATFS(ump->um_uppermp, mstat); if (error) { free(mstat, M_STATFS); return (error); } /* * The FS type etc is copy from upper vfs. * (write able vfs have priority) */ sbp->f_type = mstat->f_type; sbp->f_flags = mstat->f_flags; sbp->f_bsize = mstat->f_bsize; sbp->f_iosize = mstat->f_iosize; if (mstat->f_bsize != lbsize) sbp->f_blocks = ((off_t)sbp->f_blocks * lbsize) / mstat->f_bsize; sbp->f_blocks += mstat->f_blocks; sbp->f_bfree = mstat->f_bfree; sbp->f_bavail = mstat->f_bavail; sbp->f_files += mstat->f_files; sbp->f_ffree = mstat->f_ffree; free(mstat, M_STATFS); return (0); } static int unionfs_sync(struct mount *mp, int waitfor) { /* nothing to do */ return (0); } static int unionfs_vget(struct mount *mp, ino_t ino, int flags, struct vnode **vpp) { return (EOPNOTSUPP); } static int unionfs_fhtovp(struct mount *mp, struct fid *fidp, int flags, struct vnode **vpp) { return (EOPNOTSUPP); } static int unionfs_checkexp(struct mount *mp, struct sockaddr *nam, uint64_t *extflagsp, struct ucred **credanonp, int *numsecflavors, int *secflavors) { return (EOPNOTSUPP); } static int unionfs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp, int namespace, const char *attrname) { struct unionfs_mount *ump; struct unionfs_node *unp; ump = MOUNTTOUNIONFSMOUNT(mp); unp = VTOUNIONFS(filename_vp); if (unp->un_uppervp != NULLVP) { return (VFS_EXTATTRCTL(ump->um_uppermp, cmd, unp->un_uppervp, namespace, attrname)); } else { return (VFS_EXTATTRCTL(ump->um_lowermp, cmd, unp->un_lowervp, namespace, attrname)); } } static struct vfsops unionfs_vfsops = { .vfs_checkexp = unionfs_checkexp, .vfs_extattrctl = unionfs_extattrctl, .vfs_fhtovp = unionfs_fhtovp, .vfs_init = unionfs_init, .vfs_mount = unionfs_domount, .vfs_quotactl = unionfs_quotactl, .vfs_root = unionfs_root, .vfs_statfs = unionfs_statfs, .vfs_sync = unionfs_sync, .vfs_uninit = unionfs_uninit, .vfs_unmount = unionfs_unmount, .vfs_vget = unionfs_vget, }; VFS_SET(unionfs_vfsops, unionfs, VFCF_LOOPBACK);