f63d2e9205
access to file system subtrees to sandboxed processes. - Use of absolute paths and '..' are limited in capability mode. - Use of absolute paths and '..' are limited when looking up relative to a capability. - When a name lookup is performed, identify what operation is to be performed (such as CAP_MKDIR) as well as check for CAP_LOOKUP. With these constraints, openat() and friends are now safe in capability mode, and can then be used by code such as the capability-mode runtime linker. Approved by: re (bz), mentor (rwatson) Sponsored by: Google Inc
1251 lines
34 KiB
C
1251 lines
34 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_capsicum.h"
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#include "opt_kdtrace.h"
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/capability.h>
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#include <sys/fcntl.h>
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#include <sys/jail.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/namei.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/filedesc.h>
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#include <sys/proc.h>
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#include <sys/sdt.h>
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#include <sys/syscallsubr.h>
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#include <sys/sysctl.h>
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#ifdef KTRACE
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#include <sys/ktrace.h>
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#endif
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#include <security/audit/audit.h>
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#include <security/mac/mac_framework.h>
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#include <vm/uma.h>
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#define NAMEI_DIAGNOSTIC 1
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#undef NAMEI_DIAGNOSTIC
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SDT_PROVIDER_DECLARE(vfs);
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SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, entry, "struct vnode *", "char *",
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"unsigned long");
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SDT_PROBE_DEFINE2(vfs, namei, lookup, return, return, "int", "struct vnode *");
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/*
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* Allocation zone for namei
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*/
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uma_zone_t namei_zone;
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/*
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* Placeholder vnode for mp traversal
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*/
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static struct vnode *vp_crossmp;
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static void
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nameiinit(void *dummy __unused)
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{
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namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
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UMA_ALIGN_PTR, 0);
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getnewvnode("crossmp", NULL, &dead_vnodeops, &vp_crossmp);
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vn_lock(vp_crossmp, LK_EXCLUSIVE);
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VN_LOCK_ASHARE(vp_crossmp);
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VOP_UNLOCK(vp_crossmp, 0);
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}
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SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
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static int lookup_shared = 1;
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SYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &lookup_shared, 0,
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"Enables/Disables shared locks for path name translation");
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TUNABLE_INT("vfs.lookup_shared", &lookup_shared);
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/*
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* Convert a pathname into a pointer to a locked vnode.
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*
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* The FOLLOW flag is set when symbolic links are to be followed
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* when they occur at the end of the name translation process.
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* Symbolic links are always followed for all other pathname
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* components other than the last.
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*
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* The segflg defines whether the name is to be copied from user
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* space or kernel space.
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*
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* Overall outline of namei:
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*
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* copy in name
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* get starting directory
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* while (!done && !error) {
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* call lookup to search path.
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* if symbolic link, massage name in buffer and continue
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* }
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*/
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int
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namei(struct nameidata *ndp)
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{
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struct filedesc *fdp; /* pointer to file descriptor state */
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char *cp; /* pointer into pathname argument */
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struct vnode *dp; /* the directory we are searching */
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struct iovec aiov; /* uio for reading symbolic links */
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struct uio auio;
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int error, linklen;
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struct componentname *cnp = &ndp->ni_cnd;
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struct thread *td = cnp->cn_thread;
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struct proc *p = td->td_proc;
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int vfslocked;
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KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0,
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("NOT MPSAFE and Giant not held"));
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ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
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KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
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KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
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("namei: nameiop contaminated with flags"));
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KASSERT((cnp->cn_flags & OPMASK) == 0,
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("namei: flags contaminated with nameiops"));
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if (!lookup_shared)
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cnp->cn_flags &= ~LOCKSHARED;
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fdp = p->p_fd;
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/* We will set this ourselves if we need it. */
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cnp->cn_flags &= ~TRAILINGSLASH;
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/*
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* Get a buffer for the name to be translated, and copy the
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* name into the buffer.
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*/
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if ((cnp->cn_flags & HASBUF) == 0)
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cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
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if (ndp->ni_segflg == UIO_SYSSPACE)
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error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
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MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
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else
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error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
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MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
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if (error == 0) {
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/*
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* If we are auditing the kernel pathname, save the user
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* pathname.
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*/
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if (cnp->cn_flags & AUDITVNODE1)
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AUDIT_ARG_UPATH1(td, cnp->cn_pnbuf);
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if (cnp->cn_flags & AUDITVNODE2)
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AUDIT_ARG_UPATH2(td, cnp->cn_pnbuf);
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}
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/*
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* Don't allow empty pathnames.
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*/
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if (!error && *cnp->cn_pnbuf == '\0')
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error = ENOENT;
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#ifdef CAPABILITY_MODE
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/*
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* In capability mode, lookups must be "strictly relative" (i.e.
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* not an absolute path, and not containing '..' components) to
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* a real file descriptor, not the pseudo-descriptor AT_FDCWD.
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*/
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if (IN_CAPABILITY_MODE(td)) {
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ndp->ni_strictrelative = 1;
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if (ndp->ni_dirfd == AT_FDCWD)
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error = ECAPMODE;
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}
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#endif
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if (error) {
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uma_zfree(namei_zone, cnp->cn_pnbuf);
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#ifdef DIAGNOSTIC
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cnp->cn_pnbuf = NULL;
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cnp->cn_nameptr = NULL;
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#endif
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ndp->ni_vp = NULL;
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return (error);
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}
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ndp->ni_loopcnt = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_NAMEI)) {
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KASSERT(cnp->cn_thread == curthread,
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("namei not using curthread"));
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ktrnamei(cnp->cn_pnbuf);
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}
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#endif
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/*
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* Get starting point for the translation.
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*/
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FILEDESC_SLOCK(fdp);
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ndp->ni_rootdir = fdp->fd_rdir;
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ndp->ni_topdir = fdp->fd_jdir;
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dp = NULL;
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if (cnp->cn_pnbuf[0] != '/') {
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if (ndp->ni_startdir != NULL) {
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dp = ndp->ni_startdir;
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error = 0;
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} else if (ndp->ni_dirfd != AT_FDCWD) {
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if (cnp->cn_flags & AUDITVNODE1)
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AUDIT_ARG_ATFD1(ndp->ni_dirfd);
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if (cnp->cn_flags & AUDITVNODE2)
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AUDIT_ARG_ATFD2(ndp->ni_dirfd);
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error = fgetvp_rights(td, ndp->ni_dirfd,
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ndp->ni_rightsneeded | CAP_LOOKUP,
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&(ndp->ni_baserights), &dp);
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#ifdef CAPABILITIES
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/*
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* Lookups relative to a capability must also be
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* strictly relative.
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*
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* Note that a capability with rights CAP_MASK_VALID
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* is treated exactly like a regular file descriptor.
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*/
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if (ndp->ni_baserights != CAP_MASK_VALID)
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ndp->ni_strictrelative = 1;
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#endif
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}
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if (error != 0 || dp != NULL) {
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FILEDESC_SUNLOCK(fdp);
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if (error == 0 && dp->v_type != VDIR) {
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vfslocked = VFS_LOCK_GIANT(dp->v_mount);
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vrele(dp);
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VFS_UNLOCK_GIANT(vfslocked);
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error = ENOTDIR;
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}
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}
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if (error) {
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uma_zfree(namei_zone, cnp->cn_pnbuf);
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#ifdef DIAGNOSTIC
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cnp->cn_pnbuf = NULL;
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cnp->cn_nameptr = NULL;
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#endif
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return (error);
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}
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}
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if (dp == NULL) {
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dp = fdp->fd_cdir;
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VREF(dp);
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FILEDESC_SUNLOCK(fdp);
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if (ndp->ni_startdir != NULL) {
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vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount);
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vrele(ndp->ni_startdir);
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VFS_UNLOCK_GIANT(vfslocked);
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}
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}
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SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
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cnp->cn_flags, 0, 0);
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vfslocked = VFS_LOCK_GIANT(dp->v_mount);
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for (;;) {
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/*
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* Check if root directory should replace current directory.
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* Done at start of translation and after symbolic link.
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*/
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cnp->cn_nameptr = cnp->cn_pnbuf;
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if (*(cnp->cn_nameptr) == '/') {
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vrele(dp);
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VFS_UNLOCK_GIANT(vfslocked);
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if (ndp->ni_strictrelative != 0)
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return (ENOTCAPABLE);
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while (*(cnp->cn_nameptr) == '/') {
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cnp->cn_nameptr++;
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ndp->ni_pathlen--;
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}
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dp = ndp->ni_rootdir;
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vfslocked = VFS_LOCK_GIANT(dp->v_mount);
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VREF(dp);
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}
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if (vfslocked)
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ndp->ni_cnd.cn_flags |= GIANTHELD;
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ndp->ni_startdir = dp;
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error = lookup(ndp);
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if (error) {
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uma_zfree(namei_zone, cnp->cn_pnbuf);
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#ifdef DIAGNOSTIC
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cnp->cn_pnbuf = NULL;
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cnp->cn_nameptr = NULL;
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#endif
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SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
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0, 0);
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return (error);
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}
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vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
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ndp->ni_cnd.cn_flags &= ~GIANTHELD;
|
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/*
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* If not a symbolic link, we're done.
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*/
|
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if ((cnp->cn_flags & ISSYMLINK) == 0) {
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if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
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uma_zfree(namei_zone, cnp->cn_pnbuf);
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#ifdef DIAGNOSTIC
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cnp->cn_pnbuf = NULL;
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cnp->cn_nameptr = NULL;
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#endif
|
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} else
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cnp->cn_flags |= HASBUF;
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|
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if ((cnp->cn_flags & MPSAFE) == 0) {
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VFS_UNLOCK_GIANT(vfslocked);
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} else if (vfslocked)
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ndp->ni_cnd.cn_flags |= GIANTHELD;
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SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
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0, 0, 0);
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return (0);
|
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}
|
|
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
|
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error = ELOOP;
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break;
|
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}
|
|
#ifdef MAC
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|
if ((cnp->cn_flags & NOMACCHECK) == 0) {
|
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error = mac_vnode_check_readlink(td->td_ucred,
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ndp->ni_vp);
|
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if (error)
|
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break;
|
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}
|
|
#endif
|
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if (ndp->ni_pathlen > 1)
|
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cp = uma_zalloc(namei_zone, M_WAITOK);
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else
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cp = cnp->cn_pnbuf;
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aiov.iov_base = cp;
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aiov.iov_len = MAXPATHLEN;
|
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auio.uio_iov = &aiov;
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auio.uio_iovcnt = 1;
|
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auio.uio_offset = 0;
|
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auio.uio_rw = UIO_READ;
|
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auio.uio_segflg = UIO_SYSSPACE;
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auio.uio_td = (struct thread *)0;
|
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auio.uio_resid = MAXPATHLEN;
|
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error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
|
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if (error) {
|
|
if (ndp->ni_pathlen > 1)
|
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uma_zfree(namei_zone, cp);
|
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break;
|
|
}
|
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linklen = MAXPATHLEN - auio.uio_resid;
|
|
if (linklen == 0) {
|
|
if (ndp->ni_pathlen > 1)
|
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uma_zfree(namei_zone, cp);
|
|
error = ENOENT;
|
|
break;
|
|
}
|
|
if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
|
|
if (ndp->ni_pathlen > 1)
|
|
uma_zfree(namei_zone, cp);
|
|
error = ENAMETOOLONG;
|
|
break;
|
|
}
|
|
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;
|
|
vput(ndp->ni_vp);
|
|
dp = ndp->ni_dvp;
|
|
}
|
|
uma_zfree(namei_zone, cnp->cn_pnbuf);
|
|
#ifdef DIAGNOSTIC
|
|
cnp->cn_pnbuf = NULL;
|
|
cnp->cn_nameptr = NULL;
|
|
#endif
|
|
vput(ndp->ni_vp);
|
|
ndp->ni_vp = NULL;
|
|
vrele(ndp->ni_dvp);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
|
|
return (error);
|
|
}
|
|
|
|
static int
|
|
compute_cn_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;
|
|
}
|
|
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) {
|
|
if (mp != NULL &&
|
|
(mp->mnt_kern_flag & MNTK_EXTENDED_SHARED))
|
|
return (0);
|
|
else
|
|
return (1);
|
|
}
|
|
|
|
/*
|
|
* Lookup requests outside of open() that specify LOCKSHARED
|
|
* only need a shared lock on the leaf vnode.
|
|
*/
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Search a pathname.
|
|
* This is a very central and rather complicated routine.
|
|
*
|
|
* The pathname is pointed to by ni_ptr 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 variable
|
|
* ni_more is clear if the path is completed; it is set to one if a
|
|
* symbolic link needing interpretation is encountered.
|
|
*
|
|
* The flag argument 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 flag has LOCKPARENT or'ed into it, the parent directory is returned
|
|
* locked. If flag 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 flag
|
|
* the target is returned locked, otherwise it is returned unlocked.
|
|
* When creating or renaming and LOCKPARENT is specified, the target may not
|
|
* be ".". When deleting and LOCKPARENT is specified, the target may be ".".
|
|
*
|
|
* Overall outline of lookup:
|
|
*
|
|
* dirloop:
|
|
* identify next component of name at ndp->ni_ptr
|
|
* handle degenerate case where name is null string
|
|
* 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
|
|
* 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
|
|
lookup(struct nameidata *ndp)
|
|
{
|
|
char *cp; /* pointer into pathname argument */
|
|
struct vnode *dp = 0; /* the directory we are searching */
|
|
struct vnode *tdp; /* saved dp */
|
|
struct mount *mp; /* mount table entry */
|
|
struct prison *pr;
|
|
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 dpunlocked = 0; /* dp has already been unlocked */
|
|
struct componentname *cnp = &ndp->ni_cnd;
|
|
int vfslocked; /* VFS Giant state for child */
|
|
int dvfslocked; /* VFS Giant state for parent */
|
|
int tvfslocked;
|
|
int lkflags_save;
|
|
|
|
/*
|
|
* Setup: break out flag bits into variables.
|
|
*/
|
|
dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
|
|
vfslocked = 0;
|
|
ndp->ni_cnd.cn_flags &= ~GIANTHELD;
|
|
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
|
|
KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
|
|
("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
|
|
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;
|
|
/*
|
|
* We use shared locks until we hit the parent of the last cn then
|
|
* we adjust based on the requesting flags.
|
|
*/
|
|
if (lookup_shared)
|
|
cnp->cn_lkflags = LK_SHARED;
|
|
else
|
|
cnp->cn_lkflags = LK_EXCLUSIVE;
|
|
dp = ndp->ni_startdir;
|
|
ndp->ni_startdir = NULLVP;
|
|
vn_lock(dp,
|
|
compute_cn_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 for callers that need the name. Callers needing
|
|
* the name set the SAVENAME flag. When done, they assume
|
|
* responsibility for freeing the pathname buffer.
|
|
*/
|
|
cnp->cn_consume = 0;
|
|
for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
|
|
continue;
|
|
cnp->cn_namelen = cp - cnp->cn_nameptr;
|
|
if (cnp->cn_namelen > NAME_MAX) {
|
|
error = ENAMETOOLONG;
|
|
goto bad;
|
|
}
|
|
#ifdef NAMEI_DIAGNOSTIC
|
|
{ char c = *cp;
|
|
*cp = '\0';
|
|
printf("{%s}: ", cnp->cn_nameptr);
|
|
*cp = c; }
|
|
#endif
|
|
ndp->ni_pathlen -= cnp->cn_namelen;
|
|
ndp->ni_next = cp;
|
|
|
|
/*
|
|
* Replace multiple slashes by a single slash and trailing slashes
|
|
* by a null. 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.
|
|
*/
|
|
while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
|
|
cp++;
|
|
ndp->ni_pathlen--;
|
|
if (*cp == '\0') {
|
|
*ndp->ni_next = '\0';
|
|
cnp->cn_flags |= TRAILINGSLASH;
|
|
}
|
|
}
|
|
ndp->ni_next = cp;
|
|
|
|
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;
|
|
else
|
|
cnp->cn_flags &= ~ISDOTDOT;
|
|
if (*ndp->ni_next == 0)
|
|
cnp->cn_flags |= ISLASTCN;
|
|
else
|
|
cnp->cn_flags &= ~ISLASTCN;
|
|
|
|
if ((cnp->cn_flags & ISLASTCN) != 0 &&
|
|
cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
|
|
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
|
|
error = EINVAL;
|
|
goto bad;
|
|
}
|
|
|
|
/*
|
|
* Check for degenerate name (e.g. / or "")
|
|
* which is a way of talking about a directory,
|
|
* e.g. like "/." or ".".
|
|
*/
|
|
if (cnp->cn_nameptr[0] == '\0') {
|
|
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;
|
|
|
|
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, 0);
|
|
/* XXX This should probably move to the top of function. */
|
|
if (cnp->cn_flags & SAVESTART)
|
|
panic("lookup: SAVESTART");
|
|
goto success;
|
|
}
|
|
|
|
/*
|
|
* Handle "..": five special cases.
|
|
* 0. If doing a capability lookup, return ENOTCAPABLE (this is a
|
|
* fairly conservative design choice, but it's the only one that we
|
|
* are satisfied guarantees the property we're looking for).
|
|
* 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.
|
|
*/
|
|
if (cnp->cn_flags & ISDOTDOT) {
|
|
if (ndp->ni_strictrelative != 0) {
|
|
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;
|
|
if (dp == ndp->ni_rootdir ||
|
|
dp == ndp->ni_topdir ||
|
|
dp == rootvnode ||
|
|
pr != NULL ||
|
|
((dp->v_vflag & VV_ROOT) != 0 &&
|
|
(cnp->cn_flags & NOCROSSMOUNT) != 0)) {
|
|
ndp->ni_dvp = dp;
|
|
ndp->ni_vp = dp;
|
|
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
|
|
VREF(dp);
|
|
goto nextname;
|
|
}
|
|
if ((dp->v_vflag & VV_ROOT) == 0)
|
|
break;
|
|
if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
|
|
error = ENOENT;
|
|
goto bad;
|
|
}
|
|
tdp = dp;
|
|
dp = dp->v_mount->mnt_vnodecovered;
|
|
tvfslocked = dvfslocked;
|
|
dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
|
|
VREF(dp);
|
|
vput(tdp);
|
|
VFS_UNLOCK_GIANT(tvfslocked);
|
|
vn_lock(dp,
|
|
compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
|
|
LK_RETRY));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We now have a segment name to search for, and a directory to search.
|
|
*/
|
|
unionlookup:
|
|
#ifdef MAC
|
|
if ((cnp->cn_flags & NOMACCHECK) == 0) {
|
|
error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
|
|
cnp);
|
|
if (error)
|
|
goto bad;
|
|
}
|
|
#endif
|
|
ndp->ni_dvp = dp;
|
|
ndp->ni_vp = NULL;
|
|
ASSERT_VOP_LOCKED(dp, "lookup");
|
|
VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked));
|
|
/*
|
|
* If we have a shared lock we may need to upgrade the lock for the
|
|
* last operation.
|
|
*/
|
|
if (dp != vp_crossmp &&
|
|
VOP_ISLOCKED(dp) == LK_SHARED &&
|
|
(cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
|
|
vn_lock(dp, LK_UPGRADE|LK_RETRY);
|
|
/*
|
|
* 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;
|
|
#ifdef NAMEI_DIAGNOSTIC
|
|
vprint("lookup in", dp);
|
|
#endif
|
|
lkflags_save = cnp->cn_lkflags;
|
|
cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags);
|
|
if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
|
|
cnp->cn_lkflags = lkflags_save;
|
|
KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
|
|
#ifdef NAMEI_DIAGNOSTIC
|
|
printf("not found\n");
|
|
#endif
|
|
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;
|
|
tvfslocked = dvfslocked;
|
|
dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
|
|
VREF(dp);
|
|
vput(tdp);
|
|
VFS_UNLOCK_GIANT(tvfslocked);
|
|
vn_lock(dp,
|
|
compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
|
|
LK_RETRY));
|
|
goto unionlookup;
|
|
}
|
|
|
|
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, 0);
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (cnp->cn_flags & SAVESTART) {
|
|
ndp->ni_startdir = ndp->ni_dvp;
|
|
VREF(ndp->ni_startdir);
|
|
}
|
|
goto success;
|
|
} else
|
|
cnp->cn_lkflags = lkflags_save;
|
|
#ifdef NAMEI_DIAGNOSTIC
|
|
printf("found\n");
|
|
#endif
|
|
/*
|
|
* Take into account any additional components consumed by
|
|
* the underlying filesystem.
|
|
*/
|
|
if (cnp->cn_consume > 0) {
|
|
cnp->cn_nameptr += cnp->cn_consume;
|
|
ndp->ni_next += cnp->cn_consume;
|
|
ndp->ni_pathlen -= cnp->cn_consume;
|
|
cnp->cn_consume = 0;
|
|
}
|
|
|
|
dp = ndp->ni_vp;
|
|
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
|
|
|
|
/*
|
|
* Check to see if the vnode has been mounted on;
|
|
* if so find the root of the mounted filesystem.
|
|
*/
|
|
while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
|
|
(cnp->cn_flags & NOCROSSMOUNT) == 0) {
|
|
if (vfs_busy(mp, 0))
|
|
continue;
|
|
vput(dp);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
vfslocked = VFS_LOCK_GIANT(mp);
|
|
if (dp != ndp->ni_dvp)
|
|
vput(ndp->ni_dvp);
|
|
else
|
|
vrele(ndp->ni_dvp);
|
|
VFS_UNLOCK_GIANT(dvfslocked);
|
|
dvfslocked = 0;
|
|
vref(vp_crossmp);
|
|
ndp->ni_dvp = vp_crossmp;
|
|
error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags),
|
|
&tdp);
|
|
vfs_unbusy(mp);
|
|
if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
|
|
panic("vp_crossmp exclusively locked or reclaimed");
|
|
if (error) {
|
|
dpunlocked = 1;
|
|
goto bad2;
|
|
}
|
|
ndp->ni_vp = dp = tdp;
|
|
}
|
|
|
|
/*
|
|
* 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 (dp->v_iflag & VI_DOOMED) {
|
|
/*
|
|
* 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, 0);
|
|
goto success;
|
|
}
|
|
|
|
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 (*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);
|
|
VFS_UNLOCK_GIANT(dvfslocked);
|
|
dvfslocked = vfslocked; /* dp becomes dvp in dirloop */
|
|
vfslocked = 0;
|
|
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 (cnp->cn_flags & SAVESTART) {
|
|
ndp->ni_startdir = ndp->ni_dvp;
|
|
VREF(ndp->ni_startdir);
|
|
}
|
|
if (!wantparent) {
|
|
if (ndp->ni_dvp != dp)
|
|
vput(ndp->ni_dvp);
|
|
else
|
|
vrele(ndp->ni_dvp);
|
|
VFS_UNLOCK_GIANT(dvfslocked);
|
|
dvfslocked = 0;
|
|
} else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp)
|
|
VOP_UNLOCK(ndp->ni_dvp, 0);
|
|
|
|
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, 0);
|
|
success:
|
|
/*
|
|
* Because of lookup_shared 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 (dp->v_iflag & VI_DOOMED) {
|
|
error = ENOENT;
|
|
goto bad2;
|
|
}
|
|
}
|
|
if (vfslocked && dvfslocked)
|
|
VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */
|
|
if (vfslocked || dvfslocked)
|
|
ndp->ni_cnd.cn_flags |= GIANTHELD;
|
|
return (0);
|
|
|
|
bad2:
|
|
if (dp != ndp->ni_dvp)
|
|
vput(ndp->ni_dvp);
|
|
else
|
|
vrele(ndp->ni_dvp);
|
|
bad:
|
|
if (!dpunlocked)
|
|
vput(dp);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
VFS_UNLOCK_GIANT(dvfslocked);
|
|
ndp->ni_cnd.cn_flags &= ~GIANTHELD;
|
|
ndp->ni_vp = NULL;
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* relookup - lookup a path name component
|
|
* Used by lookup to re-acquire things.
|
|
*/
|
|
int
|
|
relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
|
|
{
|
|
struct vnode *dp = 0; /* the directory we are searching */
|
|
int wantparent; /* 1 => wantparent or lockparent flag */
|
|
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.
|
|
*/
|
|
wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
|
|
KASSERT(wantparent, ("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.
|
|
*
|
|
* The last component of the filename is left accessible via
|
|
* cnp->cn_nameptr for callers that need the name. Callers needing
|
|
* the name set the SAVENAME flag. When done, they assume
|
|
* responsibility for freeing the pathname buffer.
|
|
*/
|
|
#ifdef NAMEI_DIAGNOSTIC
|
|
printf("{%s}: ", cnp->cn_nameptr);
|
|
#endif
|
|
|
|
/*
|
|
* 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, 0);
|
|
*vpp = dp;
|
|
/* XXX This should probably move to the top of function. */
|
|
if (cnp->cn_flags & SAVESTART)
|
|
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.
|
|
*/
|
|
#ifdef NAMEI_DIAGNOSTIC
|
|
vprint("search in:", dp);
|
|
#endif
|
|
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 (cnp->cn_flags & SAVESTART)
|
|
VREF(dvp);
|
|
if ((cnp->cn_flags & LOCKPARENT) == 0)
|
|
VOP_UNLOCK(dp, 0);
|
|
/*
|
|
* 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) {
|
|
if (wantparent)
|
|
VOP_UNLOCK(dvp, 0);
|
|
else
|
|
vput(dvp);
|
|
} else if (!wantparent)
|
|
vrele(dvp);
|
|
/*
|
|
* Check for symbolic link
|
|
*/
|
|
KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
|
|
("relookup: symlink found.\n"));
|
|
|
|
/* ASSERT(dvp == ndp->ni_startdir) */
|
|
if (cnp->cn_flags & SAVESTART)
|
|
VREF(dvp);
|
|
|
|
if ((cnp->cn_flags & LOCKLEAF) == 0)
|
|
VOP_UNLOCK(dp, 0);
|
|
return (0);
|
|
bad:
|
|
vput(dp);
|
|
*vpp = NULL;
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Free data allocated by namei(); see namei(9) for details.
|
|
*/
|
|
void
|
|
NDFREE(struct nameidata *ndp, const u_int flags)
|
|
{
|
|
int unlock_dvp;
|
|
int unlock_vp;
|
|
|
|
unlock_dvp = 0;
|
|
unlock_vp = 0;
|
|
|
|
if (!(flags & NDF_NO_FREE_PNBUF) &&
|
|
(ndp->ni_cnd.cn_flags & HASBUF)) {
|
|
uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
|
|
ndp->ni_cnd.cn_flags &= ~HASBUF;
|
|
}
|
|
if (!(flags & NDF_NO_VP_UNLOCK) &&
|
|
(ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
|
|
unlock_vp = 1;
|
|
if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
|
|
if (unlock_vp) {
|
|
vput(ndp->ni_vp);
|
|
unlock_vp = 0;
|
|
} else
|
|
vrele(ndp->ni_vp);
|
|
ndp->ni_vp = NULL;
|
|
}
|
|
if (unlock_vp)
|
|
VOP_UNLOCK(ndp->ni_vp, 0);
|
|
if (!(flags & NDF_NO_DVP_UNLOCK) &&
|
|
(ndp->ni_cnd.cn_flags & LOCKPARENT) &&
|
|
ndp->ni_dvp != ndp->ni_vp)
|
|
unlock_dvp = 1;
|
|
if (!(flags & NDF_NO_DVP_RELE) &&
|
|
(ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
|
|
if (unlock_dvp) {
|
|
vput(ndp->ni_dvp);
|
|
unlock_dvp = 0;
|
|
} else
|
|
vrele(ndp->ni_dvp);
|
|
ndp->ni_dvp = NULL;
|
|
}
|
|
if (unlock_dvp)
|
|
VOP_UNLOCK(ndp->ni_dvp, 0);
|
|
if (!(flags & NDF_NO_STARTDIR_RELE) &&
|
|
(ndp->ni_cnd.cn_flags & SAVESTART)) {
|
|
vrele(ndp->ni_startdir);
|
|
ndp->ni_startdir = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Determine if there is a suitable alternate filename under the specified
|
|
* prefix for the specified path. If the create flag is set, then the
|
|
* alternate prefix will be used so long as the parent directory exists.
|
|
* This is used by the various compatiblity ABIs so that Linux binaries prefer
|
|
* files under /compat/linux for example. The chosen path (whether under
|
|
* the prefix or under /) is returned in a kernel malloc'd buffer pointed
|
|
* to by pathbuf. The caller is responsible for free'ing the buffer from
|
|
* the M_TEMP bucket if one is returned.
|
|
*/
|
|
int
|
|
kern_alternate_path(struct thread *td, const char *prefix, const char *path,
|
|
enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
|
|
{
|
|
struct nameidata nd, ndroot;
|
|
char *ptr, *buf, *cp;
|
|
size_t len, sz;
|
|
int error;
|
|
|
|
buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
|
|
*pathbuf = buf;
|
|
|
|
/* Copy the prefix into the new pathname as a starting point. */
|
|
len = strlcpy(buf, prefix, MAXPATHLEN);
|
|
if (len >= MAXPATHLEN) {
|
|
*pathbuf = NULL;
|
|
free(buf, M_TEMP);
|
|
return (EINVAL);
|
|
}
|
|
sz = MAXPATHLEN - len;
|
|
ptr = buf + len;
|
|
|
|
/* Append the filename to the prefix. */
|
|
if (pathseg == UIO_SYSSPACE)
|
|
error = copystr(path, ptr, sz, &len);
|
|
else
|
|
error = copyinstr(path, ptr, sz, &len);
|
|
|
|
if (error) {
|
|
*pathbuf = NULL;
|
|
free(buf, M_TEMP);
|
|
return (error);
|
|
}
|
|
|
|
/* Only use a prefix with absolute pathnames. */
|
|
if (*ptr != '/') {
|
|
error = EINVAL;
|
|
goto keeporig;
|
|
}
|
|
|
|
if (dirfd != AT_FDCWD) {
|
|
/*
|
|
* We want the original because the "prefix" is
|
|
* included in the already opened dirfd.
|
|
*/
|
|
bcopy(ptr, buf, len);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* We know that there is a / somewhere in this pathname.
|
|
* Search backwards for it, to find the file's parent dir
|
|
* to see if it exists in the alternate tree. If it does,
|
|
* and we want to create a file (cflag is set). We don't
|
|
* need to worry about the root comparison in this case.
|
|
*/
|
|
|
|
if (create) {
|
|
for (cp = &ptr[len] - 1; *cp != '/'; cp--);
|
|
*cp = '\0';
|
|
|
|
NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td);
|
|
error = namei(&nd);
|
|
*cp = '/';
|
|
if (error != 0)
|
|
goto keeporig;
|
|
} else {
|
|
NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td);
|
|
|
|
error = namei(&nd);
|
|
if (error != 0)
|
|
goto keeporig;
|
|
|
|
/*
|
|
* We now compare the vnode of the prefix to the one
|
|
* vnode asked. If they resolve to be the same, then we
|
|
* ignore the match so that the real root gets used.
|
|
* This avoids the problem of traversing "../.." to find the
|
|
* root directory and never finding it, because "/" resolves
|
|
* to the emulation root directory. This is expensive :-(
|
|
*/
|
|
NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix,
|
|
td);
|
|
|
|
/* We shouldn't ever get an error from this namei(). */
|
|
error = namei(&ndroot);
|
|
if (error == 0) {
|
|
if (nd.ni_vp == ndroot.ni_vp)
|
|
error = ENOENT;
|
|
|
|
NDFREE(&ndroot, NDF_ONLY_PNBUF);
|
|
vrele(ndroot.ni_vp);
|
|
VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot));
|
|
}
|
|
}
|
|
|
|
NDFREE(&nd, NDF_ONLY_PNBUF);
|
|
vrele(nd.ni_vp);
|
|
VFS_UNLOCK_GIANT(NDHASGIANT(&nd));
|
|
|
|
keeporig:
|
|
/* If there was an error, use the original path name. */
|
|
if (error)
|
|
bcopy(ptr, buf, len);
|
|
return (error);
|
|
}
|