linux_getcwd.c revision 276654
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 * 1982518Sgallatin * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 2082518Sgallatin * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 2182518Sgallatin * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 2282518Sgallatin * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 2382518Sgallatin * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 2482518Sgallatin * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 2582518Sgallatin * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 2682518Sgallatin * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 2782518Sgallatin * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 2882518Sgallatin * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 2982518Sgallatin * POSSIBILITY OF SUCH DAMAGE. 3082518Sgallatin */ 31116173Sobrien 32116173Sobrien#include <sys/cdefs.h> 33116173Sobrien__FBSDID("$FreeBSD: head/sys/compat/linux/linux_getcwd.c 276654 2015-01-04 10:34:02Z dchagin $"); 34116173Sobrien 35156874Sru#include "opt_compat.h" 3682518Sgallatin 3782518Sgallatin#include <sys/param.h> 3882518Sgallatin#include <sys/systm.h> 39112430Sphk#include <sys/namei.h> 40112430Sphk#include <sys/filedesc.h> 41112430Sphk#include <sys/kernel.h> 42112430Sphk#include <sys/file.h> 43112430Sphk#include <sys/stat.h> 44102872Siedowse#include <sys/syscallsubr.h> 45112430Sphk#include <sys/vnode.h> 46112430Sphk#include <sys/mount.h> 4782518Sgallatin#include <sys/proc.h> 48112430Sphk#include <sys/uio.h> 49112430Sphk#include <sys/malloc.h> 50112430Sphk#include <sys/dirent.h> 51112430Sphk#include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */ 5282518Sgallatin 53140214Sobrien#ifdef COMPAT_LINUX32 54140214Sobrien#include <machine/../linux32/linux.h> 55140214Sobrien#include <machine/../linux32/linux32_proto.h> 56140214Sobrien#else 5782518Sgallatin#include <machine/../linux/linux.h> 5882518Sgallatin#include <machine/../linux/linux_proto.h> 59133816Stjr#endif 60112430Sphk#include <compat/linux/linux_util.h> 6182518Sgallatin 62163606Srwatson#include <security/mac/mac_framework.h> 63163606Srwatson 64112430Sphkstatic int 65112430Sphklinux_getcwd_scandir(struct vnode **, struct vnode **, 66112430Sphk char **, char *, struct thread *); 67112430Sphkstatic int 68112430Sphklinux_getcwd_common(struct vnode *, struct vnode *, 69112430Sphk char **, char *, int, int, struct thread *); 70112430Sphk 71112430Sphk#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4) 72112430Sphk 7382518Sgallatin/* 74112430Sphk * Vnode variable naming conventions in this file: 75112430Sphk * 76112430Sphk * rvp: the current root we're aiming towards. 77112430Sphk * lvp, *lvpp: the "lower" vnode 78112430Sphk * uvp, *uvpp: the "upper" vnode. 79112430Sphk * 80112430Sphk * Since all the vnodes we're dealing with are directories, and the 81112430Sphk * lookups are going *up* in the filesystem rather than *down*, the 82112430Sphk * usual "pvp" (parent) or "dvp" (directory) naming conventions are 83112430Sphk * too confusing. 84112430Sphk */ 85112430Sphk 86112430Sphk/* 87112430Sphk * XXX Will infinite loop in certain cases if a directory read reliably 88112430Sphk * returns EINVAL on last block. 89112430Sphk * XXX is EINVAL the right thing to return if a directory is malformed? 90112430Sphk */ 91112430Sphk 92112430Sphk/* 93112430Sphk * XXX Untested vs. mount -o union; probably does the wrong thing. 94112430Sphk */ 95112430Sphk 96112430Sphk/* 97112430Sphk * Find parent vnode of *lvpp, return in *uvpp 98112430Sphk * 99112430Sphk * If we care about the name, scan it looking for name of directory 100112430Sphk * entry pointing at lvp. 101112430Sphk * 102112430Sphk * Place the name in the buffer which starts at bufp, immediately 103112430Sphk * before *bpp, and move bpp backwards to point at the start of it. 104112430Sphk * 105112430Sphk * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed 106112430Sphk * On exit, *uvpp is either NULL or is a locked vnode reference. 107112430Sphk */ 108112430Sphkstatic int 109112430Sphklinux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td) 110112430Sphk struct vnode **lvpp; 111112430Sphk struct vnode **uvpp; 112112430Sphk char **bpp; 113112430Sphk char *bufp; 114112430Sphk struct thread *td; 115112430Sphk{ 116112430Sphk int error = 0; 117112430Sphk int eofflag; 118112430Sphk off_t off; 119112430Sphk int tries; 120112430Sphk struct uio uio; 121112430Sphk struct iovec iov; 122112430Sphk char *dirbuf = NULL; 123112430Sphk int dirbuflen; 124112430Sphk ino_t fileno; 125112430Sphk struct vattr va; 126112430Sphk struct vnode *uvp = NULL; 127112430Sphk struct vnode *lvp = *lvpp; 128112430Sphk struct componentname cn; 129112430Sphk int len, reclen; 130112430Sphk tries = 0; 131112430Sphk 132112430Sphk /* 133112430Sphk * If we want the filename, get some info we need while the 134112430Sphk * current directory is still locked. 135112430Sphk */ 136112430Sphk if (bufp != NULL) { 137182371Sattilio error = VOP_GETATTR(lvp, &va, td->td_ucred); 138112430Sphk if (error) { 139112430Sphk vput(lvp); 140112430Sphk *lvpp = NULL; 141112430Sphk *uvpp = NULL; 142112430Sphk return error; 143112430Sphk } 144112430Sphk } 145112430Sphk 146112430Sphk /* 147112430Sphk * Ok, we have to do it the hard way.. 148112430Sphk * Next, get parent vnode using lookup of .. 149112430Sphk */ 150112430Sphk cn.cn_nameiop = LOOKUP; 151112430Sphk cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY; 152112430Sphk cn.cn_thread = td; 153112430Sphk cn.cn_cred = td->td_ucred; 154112430Sphk cn.cn_pnbuf = NULL; 155112430Sphk cn.cn_nameptr = ".."; 156112430Sphk cn.cn_namelen = 2; 157112430Sphk cn.cn_consume = 0; 158188588Sjhb cn.cn_lkflags = LK_SHARED; 159112430Sphk 160112430Sphk /* 161112430Sphk * At this point, lvp is locked and will be unlocked by the lookup. 162112430Sphk * On successful return, *uvpp will be locked 163112430Sphk */ 164122861Srwatson#ifdef MAC 165172930Srwatson error = mac_vnode_check_lookup(td->td_ucred, lvp, &cn); 166122861Srwatson if (error == 0) 167122861Srwatson#endif 168122861Srwatson error = VOP_LOOKUP(lvp, uvpp, &cn); 169112430Sphk if (error) { 170112430Sphk vput(lvp); 171112430Sphk *lvpp = NULL; 172112430Sphk *uvpp = NULL; 173112430Sphk return error; 174112430Sphk } 175112430Sphk uvp = *uvpp; 176112430Sphk 177112430Sphk /* If we don't care about the pathname, we're done */ 178112430Sphk if (bufp == NULL) { 179145006Sjeff vput(lvp); 180112430Sphk *lvpp = NULL; 181112430Sphk return 0; 182112430Sphk } 183112430Sphk 184112430Sphk fileno = va.va_fileid; 185112430Sphk 186112430Sphk dirbuflen = DIRBLKSIZ; 187112430Sphk if (dirbuflen < va.va_blocksize) 188112430Sphk dirbuflen = va.va_blocksize; 189276654Sdchagin dirbuf = malloc(dirbuflen, M_TEMP, M_WAITOK); 190112430Sphk 191112430Sphk#if 0 192112430Sphkunionread: 193112430Sphk#endif 194112430Sphk off = 0; 195112430Sphk do { 196112430Sphk /* call VOP_READDIR of parent */ 197112430Sphk iov.iov_base = dirbuf; 198112430Sphk iov.iov_len = dirbuflen; 199112430Sphk 200112430Sphk uio.uio_iov = &iov; 201112430Sphk uio.uio_iovcnt = 1; 202112430Sphk uio.uio_offset = off; 203112430Sphk uio.uio_resid = dirbuflen; 204112430Sphk uio.uio_segflg = UIO_SYSSPACE; 205112430Sphk uio.uio_rw = UIO_READ; 206112430Sphk uio.uio_td = td; 207112430Sphk 208112430Sphk eofflag = 0; 209112430Sphk 210112430Sphk#ifdef MAC 211172930Srwatson error = mac_vnode_check_readdir(td->td_ucred, uvp); 212112430Sphk if (error == 0) 213112430Sphk#endif /* MAC */ 214112430Sphk error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag, 215112430Sphk 0, 0); 216112430Sphk 217112430Sphk off = uio.uio_offset; 218112430Sphk 219112430Sphk /* 220112430Sphk * Try again if NFS tosses its cookies. 221112430Sphk * XXX this can still loop forever if the directory is busted 222112430Sphk * such that the second or subsequent page of it always 223112430Sphk * returns EINVAL 224112430Sphk */ 225112430Sphk if ((error == EINVAL) && (tries < 3)) { 226112430Sphk off = 0; 227112430Sphk tries++; 228112430Sphk continue; /* once more, with feeling */ 229112430Sphk } 230112430Sphk 231112430Sphk if (!error) { 232112430Sphk char *cpos; 233112430Sphk struct dirent *dp; 234112430Sphk 235112430Sphk cpos = dirbuf; 236112430Sphk tries = 0; 237112430Sphk 238112430Sphk /* scan directory page looking for matching vnode */ 239112430Sphk for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) { 240112430Sphk dp = (struct dirent *) cpos; 241112430Sphk reclen = dp->d_reclen; 242112430Sphk 243112430Sphk /* check for malformed directory.. */ 244112430Sphk if (reclen < DIRENT_MINSIZE) { 245112430Sphk error = EINVAL; 246112430Sphk goto out; 247112430Sphk } 248112430Sphk /* 249112430Sphk * XXX should perhaps do VOP_LOOKUP to 250112430Sphk * check that we got back to the right place, 251112430Sphk * but getting the locking games for that 252112430Sphk * right would be heinous. 253112430Sphk */ 254112430Sphk if ((dp->d_type != DT_WHT) && 255112430Sphk (dp->d_fileno == fileno)) { 256112430Sphk char *bp = *bpp; 257112430Sphk bp -= dp->d_namlen; 258112430Sphk 259112430Sphk if (bp <= bufp) { 260112430Sphk error = ERANGE; 261112430Sphk goto out; 262112430Sphk } 263112430Sphk bcopy(dp->d_name, bp, dp->d_namlen); 264112430Sphk error = 0; 265112430Sphk *bpp = bp; 266112430Sphk goto out; 267112430Sphk } 268112430Sphk cpos += reclen; 269112430Sphk } 270112430Sphk } 271112430Sphk } while (!eofflag); 272112430Sphk error = ENOENT; 273112430Sphk 274112430Sphkout: 275145006Sjeff vput(lvp); 276112430Sphk *lvpp = NULL; 277112430Sphk free(dirbuf, M_TEMP); 278112430Sphk return error; 279112430Sphk} 280112430Sphk 281112430Sphk 282112430Sphk/* 283112430Sphk * common routine shared by sys___getcwd() and linux_vn_isunder() 284112430Sphk */ 285112430Sphk 286112430Sphk#define GETCWD_CHECK_ACCESS 0x0001 287112430Sphk 288112430Sphkstatic int 289112430Sphklinux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td) 290112430Sphk struct vnode *lvp; 291112430Sphk struct vnode *rvp; 292112430Sphk char **bpp; 293112430Sphk char *bufp; 294112430Sphk int limit; 295112430Sphk int flags; 296112430Sphk struct thread *td; 297112430Sphk{ 298112430Sphk struct filedesc *fdp = td->td_proc->p_fd; 299112430Sphk struct vnode *uvp = NULL; 300112430Sphk char *bp = NULL; 301112430Sphk int error; 302184413Strasz accmode_t accmode = VEXEC; 303112430Sphk 304112430Sphk if (rvp == NULL) { 305112430Sphk rvp = fdp->fd_rdir; 306112430Sphk if (rvp == NULL) 307112430Sphk rvp = rootvnode; 308112430Sphk } 309112430Sphk 310112430Sphk VREF(rvp); 311112430Sphk VREF(lvp); 312112430Sphk 313112430Sphk /* 314112430Sphk * Error handling invariant: 315112430Sphk * Before a `goto out': 316112430Sphk * lvp is either NULL, or locked and held. 317112430Sphk * uvp is either NULL, or locked and held. 318112430Sphk */ 319112430Sphk 320175202Sattilio error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); 321155033Sjeff if (error != 0) 322155033Sjeff panic("vn_lock LK_RETRY returned error %d", error); 323112430Sphk if (bufp) 324112430Sphk bp = *bpp; 325112430Sphk /* 326112430Sphk * this loop will terminate when one of the following happens: 327112430Sphk * - we hit the root 328112430Sphk * - getdirentries or lookup fails 329112430Sphk * - we run out of space in the buffer. 330112430Sphk */ 331112430Sphk if (lvp == rvp) { 332112430Sphk if (bp) 333112430Sphk *(--bp) = '/'; 334112430Sphk goto out; 335112430Sphk } 336112430Sphk do { 337112430Sphk if (lvp->v_type != VDIR) { 338112430Sphk error = ENOTDIR; 339112430Sphk goto out; 340112430Sphk } 341112430Sphk 342112430Sphk /* 343112430Sphk * access check here is optional, depending on 344112430Sphk * whether or not caller cares. 345112430Sphk */ 346112430Sphk if (flags & GETCWD_CHECK_ACCESS) { 347184413Strasz error = VOP_ACCESS(lvp, accmode, td->td_ucred, td); 348112430Sphk if (error) 349112430Sphk goto out; 350184413Strasz accmode = VEXEC|VREAD; 351112430Sphk } 352112430Sphk 353112430Sphk /* 354112430Sphk * step up if we're a covered vnode.. 355112430Sphk */ 356112430Sphk while (lvp->v_vflag & VV_ROOT) { 357112430Sphk struct vnode *tvp; 358112430Sphk 359112430Sphk if (lvp == rvp) 360112430Sphk goto out; 361112430Sphk 362112430Sphk tvp = lvp; 363112430Sphk lvp = lvp->v_mount->mnt_vnodecovered; 364112430Sphk vput(tvp); 365112430Sphk /* 366112430Sphk * hodie natus est radici frater 367112430Sphk */ 368112430Sphk if (lvp == NULL) { 369112430Sphk error = ENOENT; 370112430Sphk goto out; 371112430Sphk } 372112430Sphk VREF(lvp); 373175202Sattilio error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); 374155033Sjeff if (error != 0) 375155033Sjeff panic("vn_lock LK_RETRY returned %d", error); 376112430Sphk } 377112430Sphk error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td); 378112430Sphk if (error) 379112430Sphk goto out; 380153072Sru#ifdef DIAGNOSTIC 381112430Sphk if (lvp != NULL) 382112430Sphk panic("getcwd: oops, forgot to null lvp"); 383112430Sphk if (bufp && (bp <= bufp)) { 384112430Sphk panic("getcwd: oops, went back too far"); 385112430Sphk } 386112430Sphk#endif 387112430Sphk if (bp) 388112430Sphk *(--bp) = '/'; 389112430Sphk lvp = uvp; 390112430Sphk uvp = NULL; 391112430Sphk limit--; 392112430Sphk } while ((lvp != rvp) && (limit > 0)); 393112430Sphk 394112430Sphkout: 395112430Sphk if (bpp) 396112430Sphk *bpp = bp; 397112430Sphk if (uvp) 398112430Sphk vput(uvp); 399112430Sphk if (lvp) 400112430Sphk vput(lvp); 401112430Sphk vrele(rvp); 402112430Sphk return error; 403112430Sphk} 404112430Sphk 405112430Sphk 406112430Sphk/* 40782518Sgallatin * Find pathname of process's current directory. 40882518Sgallatin * 40982518Sgallatin * Use vfs vnode-to-name reverse cache; if that fails, fall back 410112430Sphk * to reading directory contents. 41182518Sgallatin */ 41282518Sgallatin 41382518Sgallatinint 41483366Sjulianlinux_getcwd(struct thread *td, struct linux_getcwd_args *args) 41582518Sgallatin{ 416276654Sdchagin char *bp, *bend, *path; 417112430Sphk int error, len, lenused; 418112430Sphk 419112430Sphk#ifdef DEBUG 420164379Skib if (ldebug(getcwd)) 421164383Skib printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize); 422112430Sphk#endif 423112430Sphk 424112430Sphk len = args->bufsize; 425112430Sphk 426112430Sphk if (len > MAXPATHLEN*4) 427112430Sphk len = MAXPATHLEN*4; 428112430Sphk else if (len < 2) 429112430Sphk return ERANGE; 430112430Sphk 431276654Sdchagin path = malloc(len, M_TEMP, M_WAITOK); 432112430Sphk 433276654Sdchagin error = kern___getcwd(td, path, UIO_SYSSPACE, len); 434112430Sphk if (!error) { 435112430Sphk lenused = strlen(path) + 1; 436112430Sphk if (lenused <= args->bufsize) { 437112430Sphk td->td_retval[0] = lenused; 438112430Sphk error = copyout(path, args->buf, lenused); 439112430Sphk } 440112430Sphk else 441112430Sphk error = ERANGE; 442112430Sphk } else { 443112430Sphk bp = &path[len]; 444112430Sphk bend = bp; 445112430Sphk *(--bp) = '\0'; 446112430Sphk 447112430Sphk /* 448112430Sphk * 5th argument here is "max number of vnodes to traverse". 449112430Sphk * Since each entry takes up at least 2 bytes in the output buffer, 450112430Sphk * limit it to N/2 vnodes for an N byte buffer. 451112430Sphk */ 452112430Sphk 453112430Sphk error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL, 454112430Sphk &bp, path, len/2, GETCWD_CHECK_ACCESS, td); 455112430Sphk if (error) 456112430Sphk goto out; 457112430Sphk lenused = bend - bp; 458112430Sphk td->td_retval[0] = lenused; 459112430Sphk /* put the result into user buffer */ 460112430Sphk error = copyout(bp, args->buf, lenused); 461112430Sphk } 462112430Sphkout: 463112430Sphk free(path, M_TEMP); 464112430Sphk return (error); 46582518Sgallatin} 46682518Sgallatin 467