/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * 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 "opt_capsicum.h" #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif #ifdef INVARIANTS #include #endif #include #include #include #ifdef INVARIANTS static void NDVALIDATE_impl(struct nameidata *, int); #define NDVALIDATE(ndp) NDVALIDATE_impl(ndp, __LINE__) #else #define NDVALIDATE(ndp) #endif /* * Prepare namei() to restart. Reset components to its original state and set * ISRESTARTED flag which signals the underlying lookup code to change the root * from ABI root to actual root and prevents a further restarts. */ #define NDRESTART(ndp) do { \ NDREINIT_DBG(ndp); \ ndp->ni_resflags = 0; \ ndp->ni_cnd.cn_flags &= ~NAMEI_INTERNAL_FLAGS; \ ndp->ni_cnd.cn_flags |= ISRESTARTED; \ } while (0) SDT_PROVIDER_DEFINE(vfs); SDT_PROBE_DEFINE4(vfs, namei, lookup, entry, "struct vnode *", "char *", "unsigned long", "bool"); SDT_PROBE_DEFINE4(vfs, namei, lookup, return, "int", "struct vnode *", "bool", "struct nameidata"); /* Allocation zone for namei. */ uma_zone_t namei_zone; /* Placeholder vnode for mp traversal. */ static struct vnode *vp_crossmp; static int crossmp_vop_islocked(struct vop_islocked_args *ap) { return (LK_SHARED); } static int crossmp_vop_lock1(struct vop_lock1_args *ap) { struct vnode *vp; struct lock *lk __diagused; int flags; vp = ap->a_vp; lk = vp->v_vnlock; flags = ap->a_flags; KASSERT((flags & (LK_SHARED | LK_NOWAIT)) == (LK_SHARED | LK_NOWAIT), ("%s: invalid lock request 0x%x for crossmp", __func__, flags)); if ((flags & LK_INTERLOCK) != 0) VI_UNLOCK(vp); LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, ap->a_line); return (0); } static int crossmp_vop_unlock(struct vop_unlock_args *ap) { struct vnode *vp; struct lock *lk __diagused; vp = ap->a_vp; lk = vp->v_vnlock; LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE, LOCK_LINE); return (0); } static struct vop_vector crossmp_vnodeops = { .vop_default = &default_vnodeops, .vop_islocked = crossmp_vop_islocked, .vop_lock1 = crossmp_vop_lock1, .vop_unlock = crossmp_vop_unlock, }; /* * VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode * gets allocated early. See nameiinit for the direct call below. */ struct nameicap_tracker { struct vnode *dp; TAILQ_ENTRY(nameicap_tracker) nm_link; }; /* Zone for cap mode tracker elements used for dotdot capability checks. */ MALLOC_DEFINE(M_NAMEITRACKER, "namei_tracker", "namei tracking for dotdot"); static void nameiinit(void *dummy __unused) { namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); vfs_vector_op_register(&crossmp_vnodeops); getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp); vp_crossmp->v_state = VSTATE_CONSTRUCTED; vp_crossmp->v_irflag |= VIRF_CROSSMP; } SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); static int lookup_cap_dotdot = 1; SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN, &lookup_cap_dotdot, 0, "enables \"..\" components in path lookup in capability mode"); static int lookup_cap_dotdot_nonlocal = 1; SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN, &lookup_cap_dotdot_nonlocal, 0, "enables \"..\" components in path lookup in capability mode " "on non-local mount"); static void nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp) { struct nameicap_tracker *nt; if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR) return; nt = TAILQ_LAST(&ndp->ni_cap_tracker, nameicap_tracker_head); if (nt != NULL && nt->dp == dp) return; nt = malloc(sizeof(*nt), M_NAMEITRACKER, M_WAITOK); vhold(dp); nt->dp = dp; TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link); } static void nameicap_cleanup_from(struct nameidata *ndp, struct nameicap_tracker *first) { struct nameicap_tracker *nt, *nt1; nt = first; TAILQ_FOREACH_FROM_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) { TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link); vdrop(nt->dp); free(nt, M_NAMEITRACKER); } } static void nameicap_cleanup(struct nameidata *ndp) { KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) || (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative")); nameicap_cleanup_from(ndp, NULL); } /* * For dotdot lookups in capability mode, only allow the component * lookup to succeed if the resulting directory was already traversed * during the operation. This catches situations where already * traversed directory is moved to different parent, and then we walk * over it with dotdots. * * Also allow to force failure of dotdot lookups for non-local * filesystems, where external agents might assist local lookups to * escape the compartment. */ static int nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp) { struct nameicap_tracker *nt; struct mount *mp; if (dp == NULL || dp->v_type != VDIR || (ndp->ni_lcf & NI_LCF_STRICTREL) == 0) return (0); if (__predict_false((ndp->ni_lcf & (NI_LCF_STRICTREL_KTR | NI_LCF_CAP_DOTDOT_KTR)) == NI_LCF_STRICTREL_KTR)) NI_CAP_VIOLATION(ndp, ndp->ni_cnd.cn_pnbuf); if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0) return (ENOTCAPABLE); mp = dp->v_mount; if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL && (mp->mnt_flag & MNT_LOCAL) == 0) goto capfail; TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head, nm_link) { if (dp == nt->dp) { nt = TAILQ_NEXT(nt, nm_link); if (nt != NULL) nameicap_cleanup_from(ndp, nt); return (0); } } capfail: if (__predict_false((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0)) NI_CAP_VIOLATION(ndp, ndp->ni_cnd.cn_pnbuf); return (ENOTCAPABLE); } static void namei_cleanup_cnp(struct componentname *cnp) { uma_zfree(namei_zone, cnp->cn_pnbuf); cnp->cn_pnbuf = NULL; cnp->cn_nameptr = NULL; } static int namei_handle_root(struct nameidata *ndp, struct vnode **dpp) { struct componentname *cnp; cnp = &ndp->ni_cnd; if (__predict_false((ndp->ni_lcf & (NI_LCF_STRICTREL | NI_LCF_STRICTREL_KTR)) != 0)) { if ((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0) NI_CAP_VIOLATION(ndp, cnp->cn_pnbuf); if ((ndp->ni_lcf & NI_LCF_STRICTREL) != 0) return (ENOTCAPABLE); } while (*(cnp->cn_nameptr) == '/') { cnp->cn_nameptr++; ndp->ni_pathlen--; } *dpp = ndp->ni_rootdir; vrefact(*dpp); return (0); } static int namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp) { struct componentname *cnp; struct thread *td; struct pwd *pwd; int error; bool startdir_used; cnp = &ndp->ni_cnd; td = curthread; startdir_used = false; *pwdp = NULL; *dpp = NULL; #ifdef CAPABILITY_MODE /* * In capability mode, lookups must be restricted to happen in * the subtree with the root specified by the file descriptor: * - The root must be real file descriptor, not the pseudo-descriptor * AT_FDCWD. * - The passed path must be relative and not absolute. * - If lookup_cap_dotdot is disabled, path must not contain the * '..' components. * - If lookup_cap_dotdot is enabled, we verify that all '..' * components lookups result in the directories which were * previously walked by us, which prevents an escape from * the relative root. */ if ((cnp->cn_flags & NOCAPCHECK) == 0) { if (CAP_TRACING(td)) { ndp->ni_lcf |= NI_LCF_STRICTREL_KTR; if (ndp->ni_dirfd == AT_FDCWD) NI_CAP_VIOLATION(ndp, "AT_FDCWD"); } if (IN_CAPABILITY_MODE(td)) { ndp->ni_lcf |= NI_LCF_STRICTREL; ndp->ni_resflags |= NIRES_STRICTREL; if (ndp->ni_dirfd == AT_FDCWD) return (ECAPMODE); } } #endif error = 0; /* * Get starting point for the translation. */ pwd = pwd_hold(td); /* * The reference on ni_rootdir is acquired in the block below to avoid * back-to-back atomics for absolute lookups. */ namei_setup_rootdir(ndp, cnp, pwd); ndp->ni_topdir = pwd->pwd_jdir; if (cnp->cn_pnbuf[0] == '/') { ndp->ni_resflags |= NIRES_ABS; error = namei_handle_root(ndp, dpp); } else { if (ndp->ni_startdir != NULL) { *dpp = ndp->ni_startdir; startdir_used = true; } else if (ndp->ni_dirfd == AT_FDCWD) { *dpp = pwd->pwd_cdir; vrefact(*dpp); } else { if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG_ATFD1(ndp->ni_dirfd); if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG_ATFD2(ndp->ni_dirfd); error = fgetvp_lookup(ndp, dpp); } if (error == 0 && (*dpp)->v_type != VDIR && (cnp->cn_pnbuf[0] != '\0' || (cnp->cn_flags & EMPTYPATH) == 0)) error = ENOTDIR; } if (error == 0 && (cnp->cn_flags & RBENEATH) != 0) { if (cnp->cn_pnbuf[0] == '/') { error = ENOTCAPABLE; } else if ((ndp->ni_lcf & NI_LCF_STRICTREL) == 0) { ndp->ni_lcf |= NI_LCF_STRICTREL | NI_LCF_CAP_DOTDOT; } } /* * If we are auditing the kernel pathname, save the user pathname. */ if (AUDITING_TD(td)) { if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf); if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf); } if (ndp->ni_startdir != NULL && !startdir_used) vrele(ndp->ni_startdir); if (error != 0) { if (*dpp != NULL) vrele(*dpp); pwd_drop(pwd); return (error); } if (lookup_cap_dotdot != 0) { if ((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0) ndp->ni_lcf |= NI_LCF_CAP_DOTDOT_KTR; if ((ndp->ni_lcf & NI_LCF_STRICTREL) != 0) ndp->ni_lcf |= NI_LCF_CAP_DOTDOT; } SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf, cnp->cn_flags, false); *pwdp = pwd; return (0); } static int namei_getpath(struct nameidata *ndp) { struct componentname *cnp; int error; cnp = &ndp->ni_cnd; /* * Get a buffer for the name to be translated, and copy the * name into the buffer. */ cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); if (ndp->ni_segflg == UIO_SYSSPACE) { error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, &ndp->ni_pathlen); } else { error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, &ndp->ni_pathlen); } return (error); } static int namei_emptypath(struct nameidata *ndp) { struct componentname *cnp; struct pwd *pwd; struct vnode *dp; int error; cnp = &ndp->ni_cnd; MPASS(*cnp->cn_pnbuf == '\0'); MPASS((cnp->cn_flags & EMPTYPATH) != 0); MPASS((cnp->cn_flags & (LOCKPARENT | WANTPARENT)) == 0); ndp->ni_resflags |= NIRES_EMPTYPATH; error = namei_setup(ndp, &dp, &pwd); if (error != 0) { goto errout; } /* * Usecount on dp already provided by namei_setup. */ ndp->ni_vp = dp; pwd_drop(pwd); NDVALIDATE(ndp); if ((cnp->cn_flags & LOCKLEAF) != 0) { VOP_LOCK(dp, (cnp->cn_flags & LOCKSHARED) != 0 ? LK_SHARED : LK_EXCLUSIVE); if (VN_IS_DOOMED(dp)) { vput(dp); error = ENOENT; goto errout; } } SDT_PROBE4(vfs, namei, lookup, return, 0, ndp->ni_vp, false, ndp); return (0); errout: SDT_PROBE4(vfs, namei, lookup, return, error, NULL, false, ndp); namei_cleanup_cnp(cnp); return (error); } static int __noinline namei_follow_link(struct nameidata *ndp) { char *cp; struct iovec aiov; struct uio auio; struct componentname *cnp; struct thread *td; int error, linklen; error = 0; cnp = &ndp->ni_cnd; td = curthread; if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { error = ELOOP; goto out; } #ifdef MAC if ((cnp->cn_flags & NOMACCHECK) == 0) { error = mac_vnode_check_readlink(td->td_ucred, ndp->ni_vp); if (error != 0) goto out; } #endif if (ndp->ni_pathlen > 1) cp = uma_zalloc(namei_zone, M_WAITOK); else cp = cnp->cn_pnbuf; aiov.iov_base = cp; aiov.iov_len = MAXPATHLEN; auio.uio_iov = &aiov; auio.uio_iovcnt = 1; auio.uio_offset = 0; auio.uio_rw = UIO_READ; auio.uio_segflg = UIO_SYSSPACE; auio.uio_td = td; auio.uio_resid = MAXPATHLEN; error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); if (error != 0) { if (ndp->ni_pathlen > 1) uma_zfree(namei_zone, cp); goto out; } linklen = MAXPATHLEN - auio.uio_resid; if (linklen == 0) { if (ndp->ni_pathlen > 1) uma_zfree(namei_zone, cp); error = ENOENT; goto out; } if (linklen + ndp->ni_pathlen > MAXPATHLEN) { if (ndp->ni_pathlen > 1) uma_zfree(namei_zone, cp); error = ENAMETOOLONG; goto out; } if (ndp->ni_pathlen > 1) { bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); uma_zfree(namei_zone, cnp->cn_pnbuf); cnp->cn_pnbuf = cp; } else cnp->cn_pnbuf[linklen] = '\0'; ndp->ni_pathlen += linklen; out: return (error); } /* * Convert a pathname into a pointer to a locked vnode. * * The FOLLOW flag is set when symbolic links are to be followed * when they occur at the end of the name translation process. * Symbolic links are always followed for all other pathname * components other than the last. * * The segflg defines whether the name is to be copied from user * space or kernel space. * * Overall outline of namei: * * copy in name * get starting directory * while (!done && !error) { * call lookup to search path. * if symbolic link, massage name in buffer and continue * } */ int namei(struct nameidata *ndp) { struct vnode *dp; /* the directory we are searching */ struct componentname *cnp; struct thread *td; struct pwd *pwd; int error; enum cache_fpl_status status; cnp = &ndp->ni_cnd; td = curthread; #ifdef INVARIANTS KASSERT((ndp->ni_debugflags & NAMEI_DBG_CALLED) == 0, ("%s: repeated call to namei without NDREINIT", __func__)); KASSERT(ndp->ni_debugflags == NAMEI_DBG_INITED, ("%s: bad debugflags %d", __func__, ndp->ni_debugflags)); ndp->ni_debugflags |= NAMEI_DBG_CALLED; if (ndp->ni_startdir != NULL) ndp->ni_debugflags |= NAMEI_DBG_HADSTARTDIR; if (cnp->cn_flags & FAILIFEXISTS) { KASSERT(cnp->cn_nameiop == CREATE, ("%s: FAILIFEXISTS passed for op %d", __func__, cnp->cn_nameiop)); /* * The limitation below is to restrict hairy corner cases. */ KASSERT((cnp->cn_flags & (LOCKPARENT | LOCKLEAF)) == LOCKPARENT, ("%s: FAILIFEXISTS must be passed with LOCKPARENT and without LOCKLEAF", __func__)); } #endif ndp->ni_cnd.cn_cred = td->td_ucred; KASSERT(ndp->ni_resflags == 0, ("%s: garbage in ni_resflags: %x\n", __func__, ndp->ni_resflags)); KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc")); KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0, ("namei: unexpected flags: %" PRIx64 "\n", cnp->cn_flags & NAMEI_INTERNAL_FLAGS)); if (cnp->cn_flags & NOCACHE) KASSERT(cnp->cn_nameiop != LOOKUP, ("%s: NOCACHE passed with LOOKUP", __func__)); MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR || ndp->ni_startdir->v_type == VBAD); restart: ndp->ni_lcf = 0; ndp->ni_loopcnt = 0; ndp->ni_vp = NULL; error = namei_getpath(ndp); if (__predict_false(error != 0)) { namei_cleanup_cnp(cnp); SDT_PROBE4(vfs, namei, lookup, return, error, NULL, false, ndp); return (error); } cnp->cn_nameptr = cnp->cn_pnbuf; #ifdef KTRACE if (KTRPOINT(td, KTR_NAMEI)) { ktrnamei(cnp->cn_pnbuf); } #endif TSNAMEI(curthread->td_proc->p_pid, cnp->cn_pnbuf); /* * First try looking up the target without locking any vnodes. * * We may need to start from scratch or pick up where it left off. */ error = cache_fplookup(ndp, &status, &pwd); switch (status) { case CACHE_FPL_STATUS_UNSET: __assert_unreachable(); break; case CACHE_FPL_STATUS_HANDLED: if (error == 0) NDVALIDATE(ndp); else if (__predict_false(pwd->pwd_adir != pwd->pwd_rdir && (cnp->cn_flags & ISRESTARTED) == 0)) { namei_cleanup_cnp(cnp); NDRESTART(ndp); goto restart; } return (error); case CACHE_FPL_STATUS_PARTIAL: TAILQ_INIT(&ndp->ni_cap_tracker); dp = ndp->ni_startdir; break; case CACHE_FPL_STATUS_DESTROYED: ndp->ni_loopcnt = 0; error = namei_getpath(ndp); if (__predict_false(error != 0)) { namei_cleanup_cnp(cnp); return (error); } cnp->cn_nameptr = cnp->cn_pnbuf; /* FALLTHROUGH */ case CACHE_FPL_STATUS_ABORTED: TAILQ_INIT(&ndp->ni_cap_tracker); MPASS(ndp->ni_lcf == 0); if (*cnp->cn_pnbuf == '\0') { if ((cnp->cn_flags & EMPTYPATH) != 0) { return (namei_emptypath(ndp)); } namei_cleanup_cnp(cnp); SDT_PROBE4(vfs, namei, lookup, return, ENOENT, NULL, false, ndp); return (ENOENT); } error = namei_setup(ndp, &dp, &pwd); if (error != 0) { namei_cleanup_cnp(cnp); return (error); } break; } /* * Locked lookup. */ for (;;) { ndp->ni_startdir = dp; error = vfs_lookup(ndp); if (error != 0) { if (__predict_false(pwd->pwd_adir != pwd->pwd_rdir && error == ENOENT && (cnp->cn_flags & ISRESTARTED) == 0)) { nameicap_cleanup(ndp); pwd_drop(pwd); namei_cleanup_cnp(cnp); NDRESTART(ndp); goto restart; } else goto out; } /* * If not a symbolic link, we're done. */ if ((cnp->cn_flags & ISSYMLINK) == 0) { SDT_PROBE4(vfs, namei, lookup, return, error, ndp->ni_vp, false, ndp); nameicap_cleanup(ndp); pwd_drop(pwd); NDVALIDATE(ndp); return (0); } error = namei_follow_link(ndp); if (error != 0) break; vput(ndp->ni_vp); dp = ndp->ni_dvp; /* * Check if root directory should replace current directory. */ cnp->cn_nameptr = cnp->cn_pnbuf; if (*(cnp->cn_nameptr) == '/') { /* * Reset the lookup to start from the real root without * origin path name reloading. */ if (__predict_false(ndp->ni_rootdir != pwd->pwd_rdir)) { cnp->cn_flags |= ISRESTARTED; ndp->ni_rootdir = pwd->pwd_rdir; } vrele(dp); error = namei_handle_root(ndp, &dp); if (error != 0) goto out; } } vput(ndp->ni_vp); ndp->ni_vp = NULL; vrele(ndp->ni_dvp); out: MPASS(error != 0); SDT_PROBE4(vfs, namei, lookup, return, error, NULL, false, ndp); namei_cleanup_cnp(cnp); nameicap_cleanup(ndp); pwd_drop(pwd); return (error); } static int enforce_lkflags(struct mount *mp, int lkflags) { if (mp == NULL || ((lkflags & LK_SHARED) && !(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED))) { lkflags &= ~LK_SHARED; lkflags |= LK_EXCLUSIVE; } lkflags |= LK_NODDLKTREAT; return (lkflags); } static __inline int needs_exclusive_leaf(struct mount *mp, int flags) { /* * Intermediate nodes can use shared locks, we only need to * force an exclusive lock for leaf nodes. */ if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) return (0); /* Always use exclusive locks if LOCKSHARED isn't set. */ if (!(flags & LOCKSHARED)) return (1); /* * For lookups during open(), if the mount point supports * extended shared operations, then use a shared lock for the * leaf node, otherwise use an exclusive lock. */ if ((flags & ISOPEN) != 0) return (!MNT_EXTENDED_SHARED(mp)); /* * Lookup requests outside of open() that specify LOCKSHARED * only need a shared lock on the leaf vnode. */ return (0); } /* * Various filesystems expect to be able to copy a name component with length * bounded by NAME_MAX into a directory entry buffer of size MAXNAMLEN. Make * sure that these are the same size. */ _Static_assert(MAXNAMLEN == NAME_MAX, "MAXNAMLEN and NAME_MAX have different values"); static int __noinline vfs_lookup_degenerate(struct nameidata *ndp, struct vnode *dp, int wantparent) { struct componentname *cnp; struct mount *mp; int error; cnp = &ndp->ni_cnd; cnp->cn_flags |= ISLASTCN; mp = atomic_load_ptr(&dp->v_mount); if (needs_exclusive_leaf(mp, cnp->cn_flags)) { cnp->cn_lkflags &= ~LK_SHARED; cnp->cn_lkflags |= LK_EXCLUSIVE; } vn_lock(dp, enforce_lkflags(mp, cnp->cn_lkflags | LK_RETRY)); if (dp->v_type != VDIR) { error = ENOTDIR; goto bad; } if (cnp->cn_nameiop != LOOKUP) { error = EISDIR; goto bad; } if (wantparent) { ndp->ni_dvp = dp; VREF(dp); } ndp->ni_vp = dp; cnp->cn_namelen = 0; if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG_VNODE1(dp); else if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG_VNODE2(dp); if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) VOP_UNLOCK(dp); return (0); bad: VOP_UNLOCK(dp); return (error); } /* * FAILIFEXISTS handling. * * XXX namei called with LOCKPARENT but not LOCKLEAF has the strange * behaviour of leaving the vnode unlocked if the target is the same * vnode as the parent. */ static int __noinline vfs_lookup_failifexists(struct nameidata *ndp) { struct componentname *cnp __diagused; cnp = &ndp->ni_cnd; MPASS((cnp->cn_flags & ISSYMLINK) == 0); if (ndp->ni_vp == ndp->ni_dvp) vrele(ndp->ni_dvp); else vput(ndp->ni_dvp); vrele(ndp->ni_vp); ndp->ni_dvp = NULL; ndp->ni_vp = NULL; NDFREE_PNBUF(ndp); return (EEXIST); } static int __noinline vfs_lookup_cross_mount(struct nameidata *ndp) { struct componentname *cnp; struct mount *mp; struct vnode *dp, *tdp; int error, crosslkflags; bool crosslock; cnp = &ndp->ni_cnd; dp = ndp->ni_vp; /* * The vnode has been mounted on, find the root of the mounted * filesystem. */ do { mp = dp->v_mountedhere; ASSERT_VOP_LOCKED(dp, __func__); VNPASS((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0 && mp != NULL, dp); crosslock = (dp->v_vflag & VV_CROSSLOCK) != 0; crosslkflags = enforce_lkflags(mp, cnp->cn_lkflags); if (__predict_false(crosslock)) { /* * We are going to be holding the vnode lock, which * in this case is shared by the root vnode of the * filesystem mounted at mp, across the call to * VFS_ROOT(). Make the situation clear to the * filesystem by passing LK_CANRECURSE if the * lock is held exclusive, or by clearinng * LK_NODDLKTREAT to allow recursion on the shared * lock in the presence of an exclusive waiter. */ if (VOP_ISLOCKED(dp) == LK_EXCLUSIVE) { crosslkflags &= ~LK_SHARED; crosslkflags |= LK_EXCLUSIVE | LK_CANRECURSE; } else if ((crosslkflags & LK_EXCLUSIVE) != 0) { error = vn_lock(dp, LK_UPGRADE); if (error != 0) { MPASS(error == ENOENT); vrele(dp); if (dp != ndp->ni_dvp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); break; } if (dp->v_mountedhere != mp) { /* * Note that we rely on the * VIRF_MOUNTPOINT loop condition to * ensure we stop iterating if dp is * no longer a mountpoint at all. */ continue; } } else crosslkflags &= ~LK_NODDLKTREAT; } if (vfs_busy(mp, 0) != 0) continue; if (__predict_true(!crosslock)) vput(dp); if (dp != ndp->ni_dvp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); vrefact(vp_crossmp); ndp->ni_dvp = vp_crossmp; error = VFS_ROOT(mp, crosslkflags, &tdp); vfs_unbusy(mp); if (__predict_false(crosslock)) vput(dp); if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) panic("vp_crossmp exclusively locked or reclaimed"); if (error != 0) break; ndp->ni_vp = dp = tdp; } while ((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0); return (error); } /* * Search a pathname. * This is a very central and rather complicated routine. * * The pathname is pointed to by cn_nameptr and is of length ni_pathlen. * The starting directory is taken from ni_startdir. The pathname is * descended until done, or a symbolic link is encountered. The cn_flags * has ISLASTCN or'ed if the path is completed or ISSYMLINK or'ed if a * symbolic link needing interpretation is encountered. * * The cn_nameiop is LOOKUP, CREATE, RENAME, or DELETE depending on * whether the name is to be looked up, created, renamed, or deleted. * When CREATE, RENAME, or DELETE is specified, information usable in * creating, renaming, or deleting a directory entry may be calculated. * If cn_flags has LOCKPARENT or'ed into it, the parent directory is returned * locked. If it has WANTPARENT or'ed into it, the parent directory is * returned unlocked. Otherwise the parent directory is not returned. If * the target of the pathname exists and LOCKLEAF is or'ed into the cn_flags * the target is returned locked, otherwise it is returned unlocked. * * Overall outline of lookup: * * handle degenerate case where name is null string * * dirloop: * identify next component of name at ndp->ni_cnd.cn_nameptr * handle .. special cases related to capabilities, chroot, jail * if .. and crossing mount points and on mounted filesys, find parent * call VOP_LOOKUP routine for next component name * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set * component vnode returned in ni_vp (if it exists), locked. * if result vnode is mounted on and crossing mount points, * find mounted on vnode * if more components of name, do next level at dirloop * if VOP_LOOKUP returns ERELOOKUP, repeat the same level at dirloop * return the answer in ni_vp, locked if LOCKLEAF set * if LOCKPARENT set, return locked parent in ni_dvp * if WANTPARENT set, return unlocked parent in ni_dvp */ int vfs_lookup(struct nameidata *ndp) { char *cp; /* pointer into pathname argument */ char *prev_ni_next; /* saved ndp->ni_next */ char *nulchar; /* location of '\0' in cn_pnbuf */ char *lastchar; /* location of the last character */ struct vnode *dp = NULL; /* the directory we are searching */ struct vnode *tdp; /* saved dp */ struct prison *pr; size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */ int docache; /* == 0 do not cache last component */ int wantparent; /* 1 => wantparent or lockparent flag */ int rdonly; /* lookup read-only flag bit */ int error = 0; int relookup = 0; /* do not consume the path component */ struct componentname *cnp = &ndp->ni_cnd; int lkflags_save; int ni_dvp_unlocked; /* * Setup: break out flag bits into variables. */ ni_dvp_unlocked = 0; wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); /* * When set to zero, docache causes the last component of the * pathname to be deleted from the cache and the full lookup * of the name to be done (via VOP_CACHEDLOOKUP()). Often * filesystems need some pre-computed values that are made * during the full lookup, for instance UFS sets dp->i_offset. * * The docache variable is set to zero when requested by the * NOCACHE flag and for all modifying operations except CREATE. */ docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; if (cnp->cn_nameiop == DELETE || (wantparent && cnp->cn_nameiop != CREATE && cnp->cn_nameiop != LOOKUP)) docache = 0; rdonly = cnp->cn_flags & RDONLY; cnp->cn_flags &= ~ISSYMLINK; ndp->ni_dvp = NULL; cnp->cn_lkflags = LK_SHARED; dp = ndp->ni_startdir; ndp->ni_startdir = NULLVP; /* * Leading slashes, if any, are supposed to be skipped by the caller. */ MPASS(cnp->cn_nameptr[0] != '/'); /* * Check for degenerate name (e.g. / or "") which is a way of talking * about a directory, e.g. like "/." or ".". */ if (__predict_false(cnp->cn_nameptr[0] == '\0')) { error = vfs_lookup_degenerate(ndp, dp, wantparent); if (error == 0) goto success_right_lock; goto bad_unlocked; } /* * Nul-out trailing slashes (e.g., "foo///" -> "foo"). * * This must be done before VOP_LOOKUP() because some fs's don't know * about trailing slashes. Remember if there were trailing slashes to * handle symlinks, existing non-directories and non-existing files * that won't be directories specially later. */ MPASS(ndp->ni_pathlen >= 2); lastchar = &cnp->cn_nameptr[ndp->ni_pathlen - 2]; if (*lastchar == '/') { while (lastchar >= cnp->cn_pnbuf) { *lastchar = '\0'; lastchar--; ndp->ni_pathlen--; if (*lastchar != '/') { break; } } cnp->cn_flags |= TRAILINGSLASH; } /* * We use shared locks until we hit the parent of the last cn then * we adjust based on the requesting flags. */ vn_lock(dp, enforce_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); dirloop: /* * Search a new directory. * * The last component of the filename is left accessible via * cnp->cn_nameptr. It has to be freed with a call to NDFREE*. * * Store / as a temporary sentinel so that we only have one character * to test for. Pathnames tend to be short so this should not be * resulting in cache misses. */ nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1]; KASSERT(*nulchar == '\0', ("%s: expected nul at %p; string [%s]\n", __func__, nulchar, cnp->cn_pnbuf)); *nulchar = '/'; for (cp = cnp->cn_nameptr; *cp != '/'; cp++) { KASSERT(*cp != '\0', ("%s: encountered unexpected nul; string [%s]\n", __func__, cnp->cn_nameptr)); continue; } *nulchar = '\0'; cnp->cn_namelen = cp - cnp->cn_nameptr; if (__predict_false(cnp->cn_namelen > NAME_MAX)) { error = ENAMETOOLONG; goto bad; } prev_ni_pathlen = ndp->ni_pathlen; ndp->ni_pathlen -= cnp->cn_namelen; KASSERT(ndp->ni_pathlen <= PATH_MAX, ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen)); prev_ni_next = ndp->ni_next; ndp->ni_next = cp; /* * Something else should be clearing this. */ cnp->cn_flags &= ~(ISDOTDOT|ISLASTCN); cnp->cn_flags |= MAKEENTRY; if (*cp == '\0' && docache == 0) cnp->cn_flags &= ~MAKEENTRY; if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') cnp->cn_flags |= ISDOTDOT; if (*ndp->ni_next == 0) { cnp->cn_flags |= ISLASTCN; if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))) { error = EINVAL; goto bad; } } nameicap_tracker_add(ndp, dp); /* * Make sure degenerate names don't get here, their handling was * previously found in this spot. */ MPASS(cnp->cn_nameptr[0] != '\0'); /* * Handle "..": five special cases. * 0. If doing a capability lookup and lookup_cap_dotdot is * disabled, return ENOTCAPABLE. * 1. Return an error if this is the last component of * the name and the operation is DELETE or RENAME. * 2. If at root directory (e.g. after chroot) * or at absolute root directory * then ignore it so can't get out. * 3. If this vnode is the root of a mounted * filesystem, then replace it with the * vnode which was mounted on so we take the * .. in the other filesystem. * 4. If the vnode is the top directory of * the jail or chroot, don't let them out. * 5. If doing a capability lookup and lookup_cap_dotdot is * enabled, return ENOTCAPABLE if the lookup would escape * from the initial file descriptor directory. Checks are * done by ensuring that namei() already traversed the * result of dotdot lookup. */ if (cnp->cn_flags & ISDOTDOT) { if (__predict_false((ndp->ni_lcf & (NI_LCF_STRICTREL_KTR | NI_LCF_CAP_DOTDOT_KTR)) == NI_LCF_STRICTREL_KTR)) NI_CAP_VIOLATION(ndp, cnp->cn_pnbuf); if (__predict_false((ndp->ni_lcf & (NI_LCF_STRICTREL | NI_LCF_CAP_DOTDOT)) == NI_LCF_STRICTREL)) { error = ENOTCAPABLE; goto bad; } if ((cnp->cn_flags & ISLASTCN) != 0 && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { error = EINVAL; goto bad; } for (;;) { for (pr = cnp->cn_cred->cr_prison; pr != NULL; pr = pr->pr_parent) if (dp == pr->pr_root) break; bool isroot = dp == ndp->ni_rootdir || dp == ndp->ni_topdir || dp == rootvnode || pr != NULL; if (__predict_false(isroot && (ndp->ni_lcf & (NI_LCF_STRICTREL | NI_LCF_STRICTREL_KTR)) != 0)) { if ((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0) NI_CAP_VIOLATION(ndp, cnp->cn_pnbuf); if ((ndp->ni_lcf & NI_LCF_STRICTREL) != 0) { error = ENOTCAPABLE; goto capdotdot; } } if (isroot || ((dp->v_vflag & VV_ROOT) != 0 && (cnp->cn_flags & NOCROSSMOUNT) != 0)) { ndp->ni_dvp = dp; ndp->ni_vp = dp; VREF(dp); goto nextname; } if ((dp->v_vflag & VV_ROOT) == 0) break; if (VN_IS_DOOMED(dp)) { /* forced unmount */ error = ENOENT; goto bad; } tdp = dp; dp = dp->v_mount->mnt_vnodecovered; VREF(dp); vput(tdp); vn_lock(dp, enforce_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); error = nameicap_check_dotdot(ndp, dp); if (error != 0) { capdotdot: goto bad; } } } /* * We now have a segment name to search for, and a directory to search. */ unionlookup: #ifdef MAC error = mac_vnode_check_lookup(cnp->cn_cred, dp, cnp); if (__predict_false(error)) goto bad; #endif ndp->ni_dvp = dp; ndp->ni_vp = NULL; ASSERT_VOP_LOCKED(dp, "lookup"); /* * If we have a shared lock we may need to upgrade the lock for the * last operation. */ if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) && dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED) vn_lock(dp, LK_UPGRADE|LK_RETRY); if (VN_IS_DOOMED(dp)) { error = ENOENT; goto bad; } /* * If we're looking up the last component and we need an exclusive * lock, adjust our lkflags. */ if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) cnp->cn_lkflags = LK_EXCLUSIVE; lkflags_save = cnp->cn_lkflags; cnp->cn_lkflags = enforce_lkflags(dp->v_mount, cnp->cn_lkflags); error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp); cnp->cn_lkflags = lkflags_save; if (error != 0) { KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); if ((error == ENOENT) && (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && (dp->v_mount->mnt_flag & MNT_UNION)) { tdp = dp; dp = dp->v_mount->mnt_vnodecovered; VREF(dp); vput(tdp); vn_lock(dp, enforce_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); nameicap_tracker_add(ndp, dp); goto unionlookup; } if (error == ERELOOKUP) { vref(dp); ndp->ni_vp = dp; error = 0; relookup = 1; goto good; } if (error != EJUSTRETURN) goto bad; /* * At this point, we know we're at the end of the * pathname. If creating / renaming, we can consider * allowing the file or directory to be created / renamed, * provided we're not on a read-only filesystem. */ if (rdonly) { error = EROFS; goto bad; } /* trailing slash only allowed for directories */ if ((cnp->cn_flags & TRAILINGSLASH) && !(cnp->cn_flags & WILLBEDIR)) { error = ENOENT; goto bad; } if ((cnp->cn_flags & LOCKPARENT) == 0) VOP_UNLOCK(dp); /* * We return with ni_vp NULL to indicate that the entry * doesn't currently exist, leaving a pointer to the * (possibly locked) directory vnode in ndp->ni_dvp. */ goto success; } good: dp = ndp->ni_vp; /* * Check for symbolic link */ if ((dp->v_type == VLNK) && ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) || *ndp->ni_next == '/')) { cnp->cn_flags |= ISSYMLINK; if (VN_IS_DOOMED(dp)) { /* * We can't know whether the directory was mounted with * NOSYMFOLLOW, so we can't follow safely. */ error = ENOENT; goto bad2; } if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { error = EACCES; goto bad2; } /* * Symlink code always expects an unlocked dvp. */ if (ndp->ni_dvp != ndp->ni_vp) { VOP_UNLOCK(ndp->ni_dvp); ni_dvp_unlocked = 1; } goto success; } if ((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0 && (cnp->cn_flags & NOCROSSMOUNT) == 0) { error = vfs_lookup_cross_mount(ndp); if (error != 0) goto bad_unlocked; /* * FALLTHROUGH to nextname */ dp = ndp->ni_vp; } nextname: /* * Not a symbolic link that we will follow. Continue with the * next component if there is any; otherwise, we're done. */ KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', ("lookup: invalid path state.")); if (relookup) { relookup = 0; ndp->ni_pathlen = prev_ni_pathlen; ndp->ni_next = prev_ni_next; if (ndp->ni_dvp != dp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); goto dirloop; } if (cnp->cn_flags & ISDOTDOT) { error = nameicap_check_dotdot(ndp, ndp->ni_vp); if (error != 0) goto bad2; } if (*ndp->ni_next == '/') { cnp->cn_nameptr = ndp->ni_next; while (*cnp->cn_nameptr == '/') { cnp->cn_nameptr++; ndp->ni_pathlen--; } if (ndp->ni_dvp != dp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); goto dirloop; } /* * If we're processing a path with a trailing slash, * check that the end result is a directory. */ if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) { error = ENOTDIR; goto bad2; } /* * Disallow directory write attempts on read-only filesystems. */ if (rdonly && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { error = EROFS; goto bad2; } if (!wantparent) { ni_dvp_unlocked = 2; if (ndp->ni_dvp != dp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { VOP_UNLOCK(ndp->ni_dvp); ni_dvp_unlocked = 1; } if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG_VNODE1(dp); else if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG_VNODE2(dp); if ((cnp->cn_flags & LOCKLEAF) == 0) VOP_UNLOCK(dp); success: /* * FIXME: for lookups which only cross a mount point to fetch the * root vnode, ni_dvp will be set to vp_crossmp. This can be a problem * if either WANTPARENT or LOCKPARENT is set. */ /* * Because of shared lookup we may have the vnode shared locked, but * the caller may want it to be exclusively locked. */ if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { vn_lock(dp, LK_UPGRADE | LK_RETRY); if (VN_IS_DOOMED(dp)) { error = ENOENT; goto bad2; } } success_right_lock: if (ndp->ni_vp != NULL) { if ((cnp->cn_flags & ISDOTDOT) == 0) nameicap_tracker_add(ndp, ndp->ni_vp); if ((cnp->cn_flags & (FAILIFEXISTS | ISSYMLINK)) == FAILIFEXISTS) return (vfs_lookup_failifexists(ndp)); } return (0); bad2: if (ni_dvp_unlocked != 2) { if (dp != ndp->ni_dvp && !ni_dvp_unlocked) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); } bad: vput(dp); bad_unlocked: ndp->ni_vp = NULL; return (error); } /* * relookup - lookup a path name component * Used by lookup to re-acquire things. */ int vfs_relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, bool refstart) { struct vnode *dp = NULL; /* the directory we are searching */ int rdonly; /* lookup read-only flag bit */ int error = 0; KASSERT(cnp->cn_flags & ISLASTCN, ("relookup: Not given last component.")); /* * Setup: break out flag bits into variables. */ KASSERT((cnp->cn_flags & (LOCKPARENT | WANTPARENT)) != 0, ("relookup: parent not wanted")); rdonly = cnp->cn_flags & RDONLY; cnp->cn_flags &= ~ISSYMLINK; dp = dvp; cnp->cn_lkflags = LK_EXCLUSIVE; vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); /* * Search a new directory. * * See a comment in vfs_lookup for cnp->cn_nameptr. * * Check for "" which represents the root directory after slash * removal. */ if (cnp->cn_nameptr[0] == '\0') { /* * Support only LOOKUP for "/" because lookup() * can't succeed for CREATE, DELETE and RENAME. */ KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP")); KASSERT(dp->v_type == VDIR, ("dp is not a directory")); if (!(cnp->cn_flags & LOCKLEAF)) VOP_UNLOCK(dp); *vpp = dp; /* XXX This should probably move to the top of function. */ if (refstart) panic("lookup: SAVESTART"); return (0); } if (cnp->cn_flags & ISDOTDOT) panic ("relookup: lookup on dot-dot"); /* * We now have a segment name to search for, and a directory to search. */ if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { KASSERT(*vpp == NULL, ("leaf should be empty")); if (error != EJUSTRETURN) goto bad; /* * If creating and at end of pathname, then can consider * allowing file to be created. */ if (rdonly) { error = EROFS; goto bad; } /* ASSERT(dvp == ndp->ni_startdir) */ if (refstart) VREF(dvp); if ((cnp->cn_flags & LOCKPARENT) == 0) VOP_UNLOCK(dp); /* * We return with ni_vp NULL to indicate that the entry * doesn't currently exist, leaving a pointer to the * (possibly locked) directory vnode in ndp->ni_dvp. */ return (0); } dp = *vpp; /* * Disallow directory write attempts on read-only filesystems. */ if (rdonly && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { if (dvp == dp) vrele(dvp); else vput(dvp); error = EROFS; goto bad; } /* * Set the parent lock/ref state to the requested state. */ if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) VOP_UNLOCK(dvp); /* * Check for symbolic link */ KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), ("relookup: symlink found.\n")); /* ASSERT(dvp == ndp->ni_startdir) */ if (refstart) VREF(dvp); if ((cnp->cn_flags & LOCKLEAF) == 0) VOP_UNLOCK(dp); return (0); bad: vput(dp); *vpp = NULL; return (error); } #ifdef INVARIANTS /* * Validate the final state of ndp after the lookup. */ static void NDVALIDATE_impl(struct nameidata *ndp, int line) { struct componentname *cnp; cnp = &ndp->ni_cnd; if (cnp->cn_pnbuf == NULL) panic("%s: got no buf! called from %d", __func__, line); } #endif