linux_getcwd.c revision 164383
182518Sgallatin/* $OpenBSD: linux_getcwd.c,v 1.2 2001/05/16 12:50:21 ho Exp $ */ 282518Sgallatin/* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */ 382518Sgallatin/*- 482518Sgallatin * Copyright (c) 1999 The NetBSD Foundation, Inc. 582518Sgallatin * All rights reserved. 682518Sgallatin * 782518Sgallatin * This code is derived from software contributed to The NetBSD Foundation 882518Sgallatin * by Bill Sommerfeld. 982518Sgallatin * 1082518Sgallatin * Redistribution and use in source and binary forms, with or without 1182518Sgallatin * modification, are permitted provided that the following conditions 1282518Sgallatin * are met: 1382518Sgallatin * 1. Redistributions of source code must retain the above copyright 1482518Sgallatin * notice, this list of conditions and the following disclaimer. 1582518Sgallatin * 2. Redistributions in binary form must reproduce the above copyright 1682518Sgallatin * notice, this list of conditions and the following disclaimer in the 1782518Sgallatin * documentation and/or other materials provided with the distribution. 1882518Sgallatin * 3. All advertising materials mentioning features or use of this software 1982518Sgallatin * must display the following acknowledgement: 2082518Sgallatin * This product includes software developed by the NetBSD 2182518Sgallatin * Foundation, Inc. and its contributors. 2282518Sgallatin * 4. Neither the name of The NetBSD Foundation nor the names of its 2382518Sgallatin * contributors may be used to endorse or promote products derived 2482518Sgallatin * from this software without specific prior written permission. 2582518Sgallatin * 2682518Sgallatin * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 2782518Sgallatin * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 2882518Sgallatin * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 2982518Sgallatin * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 3082518Sgallatin * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 3182518Sgallatin * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 3282518Sgallatin * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 3382518Sgallatin * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 3482518Sgallatin * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 3582518Sgallatin * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 3682518Sgallatin * POSSIBILITY OF SUCH DAMAGE. 3782518Sgallatin */ 38116173Sobrien 39116173Sobrien#include <sys/cdefs.h> 40116173Sobrien__FBSDID("$FreeBSD: head/sys/compat/linux/linux_getcwd.c 164383 2006-11-18 17:27:39Z kib $"); 41116173Sobrien 42156874Sru#include "opt_compat.h" 43112430Sphk#include "opt_mac.h" 4482518Sgallatin 4582518Sgallatin#include <sys/param.h> 4682518Sgallatin#include <sys/systm.h> 47112430Sphk#include <sys/namei.h> 48112430Sphk#include <sys/filedesc.h> 49112430Sphk#include <sys/kernel.h> 50112430Sphk#include <sys/file.h> 51112430Sphk#include <sys/stat.h> 52102872Siedowse#include <sys/syscallsubr.h> 53112430Sphk#include <sys/vnode.h> 54112430Sphk#include <sys/mount.h> 5582518Sgallatin#include <sys/proc.h> 56112430Sphk#include <sys/uio.h> 57112430Sphk#include <sys/malloc.h> 58112430Sphk#include <sys/dirent.h> 59112430Sphk#include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */ 6082518Sgallatin 61140214Sobrien#ifdef COMPAT_LINUX32 62140214Sobrien#include <machine/../linux32/linux.h> 63140214Sobrien#include <machine/../linux32/linux32_proto.h> 64140214Sobrien#else 6582518Sgallatin#include <machine/../linux/linux.h> 6682518Sgallatin#include <machine/../linux/linux_proto.h> 67133816Stjr#endif 68112430Sphk#include <compat/linux/linux_util.h> 6982518Sgallatin 70163606Srwatson#include <security/mac/mac_framework.h> 71163606Srwatson 72112430Sphkstatic int 73112430Sphklinux_getcwd_scandir(struct vnode **, struct vnode **, 74112430Sphk char **, char *, struct thread *); 75112430Sphkstatic int 76112430Sphklinux_getcwd_common(struct vnode *, struct vnode *, 77112430Sphk char **, char *, int, int, struct thread *); 78112430Sphk 79112430Sphk#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4) 80112430Sphk 8182518Sgallatin/* 82112430Sphk * Vnode variable naming conventions in this file: 83112430Sphk * 84112430Sphk * rvp: the current root we're aiming towards. 85112430Sphk * lvp, *lvpp: the "lower" vnode 86112430Sphk * uvp, *uvpp: the "upper" vnode. 87112430Sphk * 88112430Sphk * Since all the vnodes we're dealing with are directories, and the 89112430Sphk * lookups are going *up* in the filesystem rather than *down*, the 90112430Sphk * usual "pvp" (parent) or "dvp" (directory) naming conventions are 91112430Sphk * too confusing. 92112430Sphk */ 93112430Sphk 94112430Sphk/* 95112430Sphk * XXX Will infinite loop in certain cases if a directory read reliably 96112430Sphk * returns EINVAL on last block. 97112430Sphk * XXX is EINVAL the right thing to return if a directory is malformed? 98112430Sphk */ 99112430Sphk 100112430Sphk/* 101112430Sphk * XXX Untested vs. mount -o union; probably does the wrong thing. 102112430Sphk */ 103112430Sphk 104112430Sphk/* 105112430Sphk * Find parent vnode of *lvpp, return in *uvpp 106112430Sphk * 107112430Sphk * If we care about the name, scan it looking for name of directory 108112430Sphk * entry pointing at lvp. 109112430Sphk * 110112430Sphk * Place the name in the buffer which starts at bufp, immediately 111112430Sphk * before *bpp, and move bpp backwards to point at the start of it. 112112430Sphk * 113112430Sphk * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed 114112430Sphk * On exit, *uvpp is either NULL or is a locked vnode reference. 115112430Sphk */ 116112430Sphkstatic int 117112430Sphklinux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td) 118112430Sphk struct vnode **lvpp; 119112430Sphk struct vnode **uvpp; 120112430Sphk char **bpp; 121112430Sphk char *bufp; 122112430Sphk struct thread *td; 123112430Sphk{ 124112430Sphk int error = 0; 125112430Sphk int eofflag; 126112430Sphk off_t off; 127112430Sphk int tries; 128112430Sphk struct uio uio; 129112430Sphk struct iovec iov; 130112430Sphk char *dirbuf = NULL; 131112430Sphk int dirbuflen; 132112430Sphk ino_t fileno; 133112430Sphk struct vattr va; 134112430Sphk struct vnode *uvp = NULL; 135112430Sphk struct vnode *lvp = *lvpp; 136112430Sphk struct componentname cn; 137112430Sphk int len, reclen; 138112430Sphk tries = 0; 139112430Sphk 140112430Sphk /* 141112430Sphk * If we want the filename, get some info we need while the 142112430Sphk * current directory is still locked. 143112430Sphk */ 144112430Sphk if (bufp != NULL) { 145112430Sphk error = VOP_GETATTR(lvp, &va, td->td_ucred, td); 146112430Sphk if (error) { 147112430Sphk vput(lvp); 148112430Sphk *lvpp = NULL; 149112430Sphk *uvpp = NULL; 150112430Sphk return error; 151112430Sphk } 152112430Sphk } 153112430Sphk 154112430Sphk /* 155112430Sphk * Ok, we have to do it the hard way.. 156112430Sphk * Next, get parent vnode using lookup of .. 157112430Sphk */ 158112430Sphk cn.cn_nameiop = LOOKUP; 159112430Sphk cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY; 160112430Sphk cn.cn_thread = td; 161112430Sphk cn.cn_cred = td->td_ucred; 162112430Sphk cn.cn_pnbuf = NULL; 163112430Sphk cn.cn_nameptr = ".."; 164112430Sphk cn.cn_namelen = 2; 165112430Sphk cn.cn_consume = 0; 166144290Sjeff cn.cn_lkflags = LK_EXCLUSIVE; 167112430Sphk 168112430Sphk /* 169112430Sphk * At this point, lvp is locked and will be unlocked by the lookup. 170112430Sphk * On successful return, *uvpp will be locked 171112430Sphk */ 172122861Srwatson#ifdef MAC 173122861Srwatson error = mac_check_vnode_lookup(td->td_ucred, lvp, &cn); 174122861Srwatson if (error == 0) 175122861Srwatson#endif 176122861Srwatson error = VOP_LOOKUP(lvp, uvpp, &cn); 177112430Sphk if (error) { 178112430Sphk vput(lvp); 179112430Sphk *lvpp = NULL; 180112430Sphk *uvpp = NULL; 181112430Sphk return error; 182112430Sphk } 183112430Sphk uvp = *uvpp; 184112430Sphk 185112430Sphk /* If we don't care about the pathname, we're done */ 186112430Sphk if (bufp == NULL) { 187145006Sjeff vput(lvp); 188112430Sphk *lvpp = NULL; 189112430Sphk return 0; 190112430Sphk } 191112430Sphk 192112430Sphk fileno = va.va_fileid; 193112430Sphk 194112430Sphk dirbuflen = DIRBLKSIZ; 195112430Sphk if (dirbuflen < va.va_blocksize) 196112430Sphk dirbuflen = va.va_blocksize; 197112430Sphk dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK); 198112430Sphk 199112430Sphk#if 0 200112430Sphkunionread: 201112430Sphk#endif 202112430Sphk off = 0; 203112430Sphk do { 204112430Sphk /* call VOP_READDIR of parent */ 205112430Sphk iov.iov_base = dirbuf; 206112430Sphk iov.iov_len = dirbuflen; 207112430Sphk 208112430Sphk uio.uio_iov = &iov; 209112430Sphk uio.uio_iovcnt = 1; 210112430Sphk uio.uio_offset = off; 211112430Sphk uio.uio_resid = dirbuflen; 212112430Sphk uio.uio_segflg = UIO_SYSSPACE; 213112430Sphk uio.uio_rw = UIO_READ; 214112430Sphk uio.uio_td = td; 215112430Sphk 216112430Sphk eofflag = 0; 217112430Sphk 218112430Sphk#ifdef MAC 219112430Sphk error = mac_check_vnode_readdir(td->td_ucred, uvp); 220112430Sphk if (error == 0) 221112430Sphk#endif /* MAC */ 222112430Sphk error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag, 223112430Sphk 0, 0); 224112430Sphk 225112430Sphk off = uio.uio_offset; 226112430Sphk 227112430Sphk /* 228112430Sphk * Try again if NFS tosses its cookies. 229112430Sphk * XXX this can still loop forever if the directory is busted 230112430Sphk * such that the second or subsequent page of it always 231112430Sphk * returns EINVAL 232112430Sphk */ 233112430Sphk if ((error == EINVAL) && (tries < 3)) { 234112430Sphk off = 0; 235112430Sphk tries++; 236112430Sphk continue; /* once more, with feeling */ 237112430Sphk } 238112430Sphk 239112430Sphk if (!error) { 240112430Sphk char *cpos; 241112430Sphk struct dirent *dp; 242112430Sphk 243112430Sphk cpos = dirbuf; 244112430Sphk tries = 0; 245112430Sphk 246112430Sphk /* scan directory page looking for matching vnode */ 247112430Sphk for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) { 248112430Sphk dp = (struct dirent *) cpos; 249112430Sphk reclen = dp->d_reclen; 250112430Sphk 251112430Sphk /* check for malformed directory.. */ 252112430Sphk if (reclen < DIRENT_MINSIZE) { 253112430Sphk error = EINVAL; 254112430Sphk goto out; 255112430Sphk } 256112430Sphk /* 257112430Sphk * XXX should perhaps do VOP_LOOKUP to 258112430Sphk * check that we got back to the right place, 259112430Sphk * but getting the locking games for that 260112430Sphk * right would be heinous. 261112430Sphk */ 262112430Sphk if ((dp->d_type != DT_WHT) && 263112430Sphk (dp->d_fileno == fileno)) { 264112430Sphk char *bp = *bpp; 265112430Sphk bp -= dp->d_namlen; 266112430Sphk 267112430Sphk if (bp <= bufp) { 268112430Sphk error = ERANGE; 269112430Sphk goto out; 270112430Sphk } 271112430Sphk bcopy(dp->d_name, bp, dp->d_namlen); 272112430Sphk error = 0; 273112430Sphk *bpp = bp; 274112430Sphk goto out; 275112430Sphk } 276112430Sphk cpos += reclen; 277112430Sphk } 278112430Sphk } 279112430Sphk } while (!eofflag); 280112430Sphk error = ENOENT; 281112430Sphk 282112430Sphkout: 283145006Sjeff vput(lvp); 284112430Sphk *lvpp = NULL; 285112430Sphk free(dirbuf, M_TEMP); 286112430Sphk return error; 287112430Sphk} 288112430Sphk 289112430Sphk 290112430Sphk/* 291112430Sphk * common routine shared by sys___getcwd() and linux_vn_isunder() 292112430Sphk */ 293112430Sphk 294112430Sphk#define GETCWD_CHECK_ACCESS 0x0001 295112430Sphk 296112430Sphkstatic int 297112430Sphklinux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td) 298112430Sphk struct vnode *lvp; 299112430Sphk struct vnode *rvp; 300112430Sphk char **bpp; 301112430Sphk char *bufp; 302112430Sphk int limit; 303112430Sphk int flags; 304112430Sphk struct thread *td; 305112430Sphk{ 306112430Sphk struct filedesc *fdp = td->td_proc->p_fd; 307112430Sphk struct vnode *uvp = NULL; 308112430Sphk char *bp = NULL; 309112430Sphk int error; 310112430Sphk int perms = VEXEC; 311112430Sphk 312112430Sphk if (rvp == NULL) { 313112430Sphk rvp = fdp->fd_rdir; 314112430Sphk if (rvp == NULL) 315112430Sphk rvp = rootvnode; 316112430Sphk } 317112430Sphk 318112430Sphk VREF(rvp); 319112430Sphk VREF(lvp); 320112430Sphk 321112430Sphk /* 322112430Sphk * Error handling invariant: 323112430Sphk * Before a `goto out': 324112430Sphk * lvp is either NULL, or locked and held. 325112430Sphk * uvp is either NULL, or locked and held. 326112430Sphk */ 327112430Sphk 328112430Sphk error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); 329155033Sjeff if (error != 0) 330155033Sjeff panic("vn_lock LK_RETRY returned error %d", error); 331112430Sphk if (bufp) 332112430Sphk bp = *bpp; 333112430Sphk /* 334112430Sphk * this loop will terminate when one of the following happens: 335112430Sphk * - we hit the root 336112430Sphk * - getdirentries or lookup fails 337112430Sphk * - we run out of space in the buffer. 338112430Sphk */ 339112430Sphk if (lvp == rvp) { 340112430Sphk if (bp) 341112430Sphk *(--bp) = '/'; 342112430Sphk goto out; 343112430Sphk } 344112430Sphk do { 345112430Sphk if (lvp->v_type != VDIR) { 346112430Sphk error = ENOTDIR; 347112430Sphk goto out; 348112430Sphk } 349112430Sphk 350112430Sphk /* 351112430Sphk * access check here is optional, depending on 352112430Sphk * whether or not caller cares. 353112430Sphk */ 354112430Sphk if (flags & GETCWD_CHECK_ACCESS) { 355112430Sphk error = VOP_ACCESS(lvp, perms, td->td_ucred, td); 356112430Sphk if (error) 357112430Sphk goto out; 358112430Sphk perms = VEXEC|VREAD; 359112430Sphk } 360112430Sphk 361112430Sphk /* 362112430Sphk * step up if we're a covered vnode.. 363112430Sphk */ 364112430Sphk while (lvp->v_vflag & VV_ROOT) { 365112430Sphk struct vnode *tvp; 366112430Sphk 367112430Sphk if (lvp == rvp) 368112430Sphk goto out; 369112430Sphk 370112430Sphk tvp = lvp; 371112430Sphk lvp = lvp->v_mount->mnt_vnodecovered; 372112430Sphk vput(tvp); 373112430Sphk /* 374112430Sphk * hodie natus est radici frater 375112430Sphk */ 376112430Sphk if (lvp == NULL) { 377112430Sphk error = ENOENT; 378112430Sphk goto out; 379112430Sphk } 380112430Sphk VREF(lvp); 381112430Sphk error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); 382155033Sjeff if (error != 0) 383155033Sjeff panic("vn_lock LK_RETRY returned %d", error); 384112430Sphk } 385112430Sphk error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td); 386112430Sphk if (error) 387112430Sphk goto out; 388153072Sru#ifdef DIAGNOSTIC 389112430Sphk if (lvp != NULL) 390112430Sphk panic("getcwd: oops, forgot to null lvp"); 391112430Sphk if (bufp && (bp <= bufp)) { 392112430Sphk panic("getcwd: oops, went back too far"); 393112430Sphk } 394112430Sphk#endif 395112430Sphk if (bp) 396112430Sphk *(--bp) = '/'; 397112430Sphk lvp = uvp; 398112430Sphk uvp = NULL; 399112430Sphk limit--; 400112430Sphk } while ((lvp != rvp) && (limit > 0)); 401112430Sphk 402112430Sphkout: 403112430Sphk if (bpp) 404112430Sphk *bpp = bp; 405112430Sphk if (uvp) 406112430Sphk vput(uvp); 407112430Sphk if (lvp) 408112430Sphk vput(lvp); 409112430Sphk vrele(rvp); 410112430Sphk return error; 411112430Sphk} 412112430Sphk 413112430Sphk 414112430Sphk/* 41582518Sgallatin * Find pathname of process's current directory. 41682518Sgallatin * 41782518Sgallatin * Use vfs vnode-to-name reverse cache; if that fails, fall back 418112430Sphk * to reading directory contents. 41982518Sgallatin */ 42082518Sgallatin 42182518Sgallatinint 42283366Sjulianlinux_getcwd(struct thread *td, struct linux_getcwd_args *args) 42382518Sgallatin{ 424112430Sphk caddr_t bp, bend, path; 425112430Sphk int error, len, lenused; 426112430Sphk 427112430Sphk#ifdef DEBUG 428164379Skib if (ldebug(getcwd)) 429164383Skib printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize); 430112430Sphk#endif 431112430Sphk 432112430Sphk len = args->bufsize; 433112430Sphk 434112430Sphk if (len > MAXPATHLEN*4) 435112430Sphk len = MAXPATHLEN*4; 436112430Sphk else if (len < 2) 437112430Sphk return ERANGE; 438112430Sphk 439112430Sphk path = (char *)malloc(len, M_TEMP, M_WAITOK); 440112430Sphk 441112430Sphk error = kern___getcwd(td, path, UIO_SYSSPACE, len); 442112430Sphk if (!error) { 443112430Sphk lenused = strlen(path) + 1; 444112430Sphk if (lenused <= args->bufsize) { 445112430Sphk td->td_retval[0] = lenused; 446112430Sphk error = copyout(path, args->buf, lenused); 447112430Sphk } 448112430Sphk else 449112430Sphk error = ERANGE; 450112430Sphk } else { 451112430Sphk bp = &path[len]; 452112430Sphk bend = bp; 453112430Sphk *(--bp) = '\0'; 454112430Sphk 455112430Sphk /* 456112430Sphk * 5th argument here is "max number of vnodes to traverse". 457112430Sphk * Since each entry takes up at least 2 bytes in the output buffer, 458112430Sphk * limit it to N/2 vnodes for an N byte buffer. 459112430Sphk */ 460112430Sphk 461147854Sjhb mtx_lock(&Giant); 462112430Sphk error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL, 463112430Sphk &bp, path, len/2, GETCWD_CHECK_ACCESS, td); 464147854Sjhb mtx_unlock(&Giant); 465112430Sphk 466112430Sphk if (error) 467112430Sphk goto out; 468112430Sphk lenused = bend - bp; 469112430Sphk td->td_retval[0] = lenused; 470112430Sphk /* put the result into user buffer */ 471112430Sphk error = copyout(bp, args->buf, lenused); 472112430Sphk } 473112430Sphkout: 474112430Sphk free(path, M_TEMP); 475112430Sphk return (error); 47682518Sgallatin} 47782518Sgallatin 478