| 1 | /* |
| 2 | * Copyright (c) 2004 The DragonFly Project. All rights reserved. |
| 3 | * |
| 4 | * This code is derived from software contributed to The DragonFly Project |
| 5 | * by Matthew Dillon <dillon@backplane.com> |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in |
| 15 | * the documentation and/or other materials provided with the |
| 16 | * distribution. |
| 17 | * 3. Neither the name of The DragonFly Project nor the names of its |
| 18 | * contributors may be used to endorse or promote products derived |
| 19 | * from this software without specific, prior written permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 23 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 24 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 25 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 26 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 27 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 28 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 29 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 30 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| 31 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 32 | * SUCH DAMAGE. |
| 33 | * |
| 34 | * $DragonFly: src/sys/kern/vfs_nlookup.c,v 1.18 2006/08/12 00:26:20 dillon Exp $ |
| 35 | */ |
| 36 | /* |
| 37 | * nlookup() is the 'new' namei interface. Rather then return directory and |
| 38 | * leaf vnodes (in various lock states) the new interface instead deals in |
| 39 | * namecache records. Namecache records may represent both a positive or |
| 40 | * a negative hit. The namespace is locked via the namecache record instead |
| 41 | * of via the vnode, and only the leaf namecache record (representing the |
| 42 | * filename) needs to be locked. |
| 43 | * |
| 44 | * This greatly improves filesystem parallelism and is a huge simplification |
| 45 | * of the API verses the old vnode locking / namei scheme. |
| 46 | * |
| 47 | * Filesystems must actively control the caching aspects of the namecache, |
| 48 | * and since namecache pointers are used as handles they are non-optional |
| 49 | * even for filesystems which do not generally wish to cache things. It is |
| 50 | * intended that a separate cache coherency API will be constructed to handle |
| 51 | * these issues. |
| 52 | */ |
| 53 | |
| 54 | #include "opt_ktrace.h" |
| 55 | |
| 56 | #include <sys/param.h> |
| 57 | #include <sys/systm.h> |
| 58 | #include <sys/kernel.h> |
| 59 | #include <sys/vnode.h> |
| 60 | #include <sys/mount.h> |
| 61 | #include <sys/filedesc.h> |
| 62 | #include <sys/proc.h> |
| 63 | #include <sys/namei.h> |
| 64 | #include <sys/nlookup.h> |
| 65 | #include <sys/malloc.h> |
| 66 | #include <sys/stat.h> |
| 67 | #include <sys/objcache.h> |
| 68 | |
| 69 | #ifdef KTRACE |
| 70 | #include <sys/ktrace.h> |
| 71 | #endif |
| 72 | |
| 73 | /* |
| 74 | * Initialize a nlookup() structure, early error return for copyin faults |
| 75 | * or a degenerate empty string (which is not allowed). |
| 76 | * |
| 77 | * The first process proc0's credentials are used if the calling thread |
| 78 | * is not associated with a process context. |
| 79 | */ |
| 80 | int |
| 81 | nlookup_init(struct nlookupdata *nd, |
| 82 | const char *path, enum uio_seg seg, int flags) |
| 83 | { |
| 84 | size_t pathlen; |
| 85 | struct proc *p; |
| 86 | thread_t td; |
| 87 | int error; |
| 88 | |
| 89 | td = curthread; |
| 90 | p = td->td_proc; |
| 91 | |
| 92 | /* |
| 93 | * note: the pathlen set by copy*str() includes the terminating \0. |
| 94 | */ |
| 95 | bzero(nd, sizeof(struct nlookupdata)); |
| 96 | nd->nl_path = objcache_get(namei_oc, M_WAITOK); |
| 97 | nd->nl_flags |= NLC_HASBUF; |
| 98 | if (seg == UIO_SYSSPACE) |
| 99 | error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen); |
| 100 | else |
| 101 | error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen); |
| 102 | |
| 103 | /* |
| 104 | * Don't allow empty pathnames. |
| 105 | * POSIX.1 requirement: "" is not a vaild file name. |
| 106 | */ |
| 107 | if (error == 0 && pathlen <= 1) |
| 108 | error = ENOENT; |
| 109 | |
| 110 | if (error == 0) { |
| 111 | if (p && p->p_fd) { |
| 112 | nd->nl_ncp = cache_hold(p->p_fd->fd_ncdir); |
| 113 | nd->nl_rootncp = cache_hold(p->p_fd->fd_nrdir); |
| 114 | if (p->p_fd->fd_njdir) |
| 115 | nd->nl_jailncp = cache_hold(p->p_fd->fd_njdir); |
| 116 | nd->nl_cred = crhold(p->p_ucred); |
| 117 | } else { |
| 118 | nd->nl_ncp = cache_hold(rootncp); |
| 119 | nd->nl_rootncp = cache_hold(nd->nl_ncp); |
| 120 | nd->nl_jailncp = cache_hold(nd->nl_ncp); |
| 121 | nd->nl_cred = crhold(proc0.p_ucred); |
| 122 | } |
| 123 | nd->nl_td = td; |
| 124 | nd->nl_flags |= flags; |
| 125 | } else { |
| 126 | nlookup_done(nd); |
| 127 | } |
| 128 | return(error); |
| 129 | } |
| 130 | |
| 131 | /* |
| 132 | * This works similarly to nlookup_init() but does not assume a process |
| 133 | * context. rootncp is always chosen for the root directory and the cred |
| 134 | * and starting directory are supplied in arguments. |
| 135 | */ |
| 136 | int |
| 137 | nlookup_init_raw(struct nlookupdata *nd, |
| 138 | const char *path, enum uio_seg seg, int flags, |
| 139 | struct ucred *cred, struct namecache *ncstart) |
| 140 | { |
| 141 | size_t pathlen; |
| 142 | thread_t td; |
| 143 | int error; |
| 144 | |
| 145 | td = curthread; |
| 146 | |
| 147 | bzero(nd, sizeof(struct nlookupdata)); |
| 148 | nd->nl_path = objcache_get(namei_oc, M_WAITOK); |
| 149 | nd->nl_flags |= NLC_HASBUF; |
| 150 | if (seg == UIO_SYSSPACE) |
| 151 | error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen); |
| 152 | else |
| 153 | error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen); |
| 154 | |
| 155 | /* |
| 156 | * Don't allow empty pathnames. |
| 157 | * POSIX.1 requirement: "" is not a vaild file name. |
| 158 | */ |
| 159 | if (error == 0 && pathlen <= 1) |
| 160 | error = ENOENT; |
| 161 | |
| 162 | if (error == 0) { |
| 163 | nd->nl_ncp = cache_hold(ncstart); |
| 164 | nd->nl_rootncp = cache_hold(rootncp); |
| 165 | nd->nl_jailncp = cache_hold(rootncp); |
| 166 | nd->nl_cred = crhold(cred); |
| 167 | nd->nl_td = td; |
| 168 | nd->nl_flags |= flags; |
| 169 | } else { |
| 170 | nlookup_done(nd); |
| 171 | } |
| 172 | return(error); |
| 173 | } |
| 174 | |
| 175 | /* |
| 176 | * Set a different credential; this credential will be used by future |
| 177 | * operations performed on nd.nl_open_vp and nlookupdata structure. |
| 178 | */ |
| 179 | void |
| 180 | nlookup_set_cred(struct nlookupdata *nd, struct ucred *cred) |
| 181 | { |
| 182 | KKASSERT(nd->nl_cred != NULL); |
| 183 | |
| 184 | if (nd->nl_cred != cred) { |
| 185 | cred = crhold(cred); |
| 186 | crfree(nd->nl_cred); |
| 187 | nd->nl_cred = cred; |
| 188 | } |
| 189 | } |
| 190 | |
| 191 | /* |
| 192 | * Cleanup a nlookupdata structure after we are through with it. This may |
| 193 | * be called on any nlookupdata structure initialized with nlookup_init(). |
| 194 | * Calling nlookup_done() is mandatory in all cases except where nlookup_init() |
| 195 | * returns an error, even if as a consumer you believe you have taken all |
| 196 | * dynamic elements out of the nlookupdata structure. |
| 197 | */ |
| 198 | void |
| 199 | nlookup_done(struct nlookupdata *nd) |
| 200 | { |
| 201 | if (nd->nl_ncp) { |
| 202 | if (nd->nl_flags & NLC_NCPISLOCKED) { |
| 203 | nd->nl_flags &= ~NLC_NCPISLOCKED; |
| 204 | cache_unlock(nd->nl_ncp); |
| 205 | } |
| 206 | cache_drop(nd->nl_ncp); |
| 207 | nd->nl_ncp = NULL; |
| 208 | } |
| 209 | if (nd->nl_rootncp) { |
| 210 | cache_drop(nd->nl_rootncp); |
| 211 | nd->nl_rootncp = NULL; |
| 212 | } |
| 213 | if (nd->nl_jailncp) { |
| 214 | cache_drop(nd->nl_jailncp); |
| 215 | nd->nl_jailncp = NULL; |
| 216 | } |
| 217 | if ((nd->nl_flags & NLC_HASBUF) && nd->nl_path) { |
| 218 | objcache_put(namei_oc, nd->nl_path); |
| 219 | nd->nl_path = NULL; |
| 220 | } |
| 221 | if (nd->nl_cred) { |
| 222 | crfree(nd->nl_cred); |
| 223 | nd->nl_cred = NULL; |
| 224 | } |
| 225 | if (nd->nl_open_vp) { |
| 226 | if (nd->nl_flags & NLC_LOCKVP) { |
| 227 | vn_unlock(nd->nl_open_vp); |
| 228 | nd->nl_flags &= ~NLC_LOCKVP; |
| 229 | } |
| 230 | vn_close(nd->nl_open_vp, nd->nl_vp_fmode); |
| 231 | nd->nl_open_vp = NULL; |
| 232 | } |
| 233 | nd->nl_flags = 0; /* clear remaining flags (just clear everything) */ |
| 234 | } |
| 235 | |
| 236 | void |
| 237 | nlookup_zero(struct nlookupdata *nd) |
| 238 | { |
| 239 | bzero(nd, sizeof(struct nlookupdata)); |
| 240 | } |
| 241 | |
| 242 | /* |
| 243 | * Simple all-in-one nlookup. Returns a locked namecache structure or NULL |
| 244 | * if an error occured. |
| 245 | * |
| 246 | * Note that the returned ncp is not checked for permissions, though VEXEC |
| 247 | * is checked on the directory path leading up to the result. The caller |
| 248 | * must call naccess() to check the permissions of the returned leaf. |
| 249 | */ |
| 250 | struct namecache * |
| 251 | nlookup_simple(const char *str, enum uio_seg seg, |
| 252 | int niflags, int *error) |
| 253 | { |
| 254 | struct nlookupdata nd; |
| 255 | struct namecache *ncp; |
| 256 | |
| 257 | *error = nlookup_init(&nd, str, seg, niflags); |
| 258 | if (*error == 0) { |
| 259 | if ((*error = nlookup(&nd)) == 0) { |
| 260 | ncp = nd.nl_ncp; /* keep hold ref from structure */ |
| 261 | nd.nl_ncp = NULL; /* and NULL out */ |
| 262 | } else { |
| 263 | ncp = NULL; |
| 264 | } |
| 265 | nlookup_done(&nd); |
| 266 | } else { |
| 267 | ncp = NULL; |
| 268 | } |
| 269 | return(ncp); |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Do a generic nlookup. Note that the passed nd is not nlookup_done()'d |
| 274 | * on return, even if an error occurs. If no error occurs the returned |
| 275 | * nl_ncp is always referenced and locked, otherwise it may or may not be. |
| 276 | * |
| 277 | * Intermediate directory elements, including the current directory, require |
| 278 | * execute (search) permission. nlookup does not examine the access |
| 279 | * permissions on the returned element. |
| 280 | * |
| 281 | * If NLC_CREATE or NLC_DELETE is set the last directory must allow node |
| 282 | * creation (VCREATE/VDELETE), and an error code of 0 will be returned for |
| 283 | * a non-existant target. Otherwise a non-existant target will cause |
| 284 | * ENOENT to be returned. |
| 285 | */ |
| 286 | int |
| 287 | nlookup(struct nlookupdata *nd) |
| 288 | { |
| 289 | struct nlcomponent nlc; |
| 290 | struct namecache *ncp; |
| 291 | int wasdotordotdot; |
| 292 | char *ptr; |
| 293 | char *xptr; |
| 294 | int error; |
| 295 | int len; |
| 296 | |
| 297 | #ifdef KTRACE |
| 298 | if (KTRPOINT(nd->nl_td, KTR_NAMEI)) |
| 299 | ktrnamei(nd->nl_td->td_proc, nd->nl_path); |
| 300 | #endif |
| 301 | bzero(&nlc, sizeof(nlc)); |
| 302 | |
| 303 | /* |
| 304 | * Setup for the loop. The current working namecache element must |
| 305 | * be in a refd + unlocked state. This typically the case on entry except |
| 306 | * when stringing nlookup()'s along in a chain, since nlookup() always |
| 307 | * returns nl_ncp in a locked state. |
| 308 | */ |
| 309 | nd->nl_loopcnt = 0; |
| 310 | if (nd->nl_flags & NLC_NCPISLOCKED) { |
| 311 | nd->nl_flags &= ~NLC_NCPISLOCKED; |
| 312 | cache_unlock(nd->nl_ncp); |
| 313 | } |
| 314 | ptr = nd->nl_path; |
| 315 | |
| 316 | /* |
| 317 | * Loop on the path components. At the top of the loop nd->nl_ncp |
| 318 | * is ref'd and unlocked and represents our current position. |
| 319 | */ |
| 320 | for (;;) { |
| 321 | /* |
| 322 | * Check if the root directory should replace the current |
| 323 | * directory. This is done at the start of a translation |
| 324 | * or after a symbolic link has been found. In other cases |
| 325 | * ptr will never be pointing at a '/'. |
| 326 | */ |
| 327 | if (*ptr == '/') { |
| 328 | do { |
| 329 | ++ptr; |
| 330 | } while (*ptr == '/'); |
| 331 | ncp = cache_hold(nd->nl_rootncp); |
| 332 | cache_drop(nd->nl_ncp); |
| 333 | nd->nl_ncp = ncp; |
| 334 | if (*ptr == 0) { |
| 335 | cache_lock(nd->nl_ncp); |
| 336 | nd->nl_flags |= NLC_NCPISLOCKED; |
| 337 | error = 0; |
| 338 | break; |
| 339 | } |
| 340 | continue; |
| 341 | } |
| 342 | |
| 343 | /* |
| 344 | * Check directory search permissions |
| 345 | */ |
| 346 | if ((error = naccess(nd->nl_ncp, VEXEC, nd->nl_cred)) != 0) |
| 347 | break; |
| 348 | |
| 349 | /* |
| 350 | * Extract the path component |
| 351 | */ |
| 352 | nlc.nlc_nameptr = ptr; |
| 353 | while (*ptr && *ptr != '/') |
| 354 | ++ptr; |
| 355 | nlc.nlc_namelen = ptr - nlc.nlc_nameptr; |
| 356 | |
| 357 | /* |
| 358 | * Lookup the path component in the cache, creating an unresolved |
| 359 | * entry if necessary. We have to handle "." and ".." as special |
| 360 | * cases. |
| 361 | * |
| 362 | * When handling ".." we have to detect a traversal back through a |
| 363 | * mount point and skip the mount-under node. If we are at the root |
| 364 | * ".." just returns the root. |
| 365 | * |
| 366 | * This subsection returns a locked, refd 'ncp' unless it errors out. |
| 367 | * The namecache topology is not allowed to be disconnected, so |
| 368 | * encountering a NULL parent will generate EINVAL. This typically |
| 369 | * occurs when a directory is removed out from under a process. |
| 370 | * |
| 371 | * If NLC_DELETE is set neither '.' or '..' can be the last component |
| 372 | * of a path. |
| 373 | */ |
| 374 | if (nlc.nlc_namelen == 1 && nlc.nlc_nameptr[0] == '.') { |
| 375 | ncp = cache_get(nd->nl_ncp); |
| 376 | wasdotordotdot = 1; |
| 377 | } else if (nlc.nlc_namelen == 2 && |
| 378 | nlc.nlc_nameptr[0] == '.' && nlc.nlc_nameptr[1] == '.') { |
| 379 | ncp = nd->nl_ncp; |
| 380 | if (ncp == nd->nl_rootncp) { |
| 381 | ncp = cache_get(ncp); |
| 382 | } else { |
| 383 | while ((ncp->nc_flag & NCF_MOUNTPT) && ncp != nd->nl_rootncp) { |
| 384 | if (ncp->nc_parent->nc_flag & NCF_DESTROYED) |
| 385 | break; |
| 386 | ncp = ncp->nc_parent; /* get to underlying node */ |
| 387 | KKASSERT(ncp != NULL && 1); |
| 388 | } |
| 389 | if (ncp != nd->nl_rootncp) { |
| 390 | if (ncp->nc_parent->nc_flag & NCF_DESTROYED) { |
| 391 | error = EINVAL; |
| 392 | break; |
| 393 | } |
| 394 | ncp = ncp->nc_parent; |
| 395 | if (ncp == NULL) { |
| 396 | error = EINVAL; |
| 397 | break; |
| 398 | } |
| 399 | } |
| 400 | ncp = cache_get(ncp); |
| 401 | } |
| 402 | wasdotordotdot = 1; |
| 403 | } else { |
| 404 | ncp = cache_nlookup(nd->nl_ncp, &nlc); |
| 405 | while ((error = cache_resolve(ncp, nd->nl_cred)) == EAGAIN) { |
| 406 | printf("[diagnostic] nlookup: relookup %*.*s\n", |
| 407 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 408 | cache_put(ncp); |
| 409 | ncp = cache_nlookup(nd->nl_ncp, &nlc); |
| 410 | } |
| 411 | wasdotordotdot = 0; |
| 412 | } |
| 413 | /* |
| 414 | * [end of subsection] ncp is locked and ref'd. nd->nl_ncp is ref'd |
| 415 | */ |
| 416 | |
| 417 | /* |
| 418 | * Resolve the namespace if necessary. The ncp returned by |
| 419 | * cache_nlookup() is referenced and locked. |
| 420 | * |
| 421 | * XXX neither '.' nor '..' should return EAGAIN since they were |
| 422 | * previously resolved and thus cannot be newly created ncp's. |
| 423 | */ |
| 424 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 425 | error = cache_resolve(ncp, nd->nl_cred); |
| 426 | KKASSERT(error != EAGAIN); |
| 427 | } else { |
| 428 | error = ncp->nc_error; |
| 429 | } |
| 430 | |
| 431 | /* |
| 432 | * Early completion. ENOENT is not an error if this is the last |
| 433 | * component and NLC_CREATE was requested. Note that ncp->nc_error |
| 434 | * is left as ENOENT in that case, which we check later on. |
| 435 | * |
| 436 | * Also handle invalid '.' or '..' components terminating a path |
| 437 | * during removal. The standard requires this and pax pretty |
| 438 | *stupidly depends on it. |
| 439 | */ |
| 440 | for (xptr = ptr; *xptr == '/'; ++xptr) |
| 441 | ; |
| 442 | if (*xptr == 0) { |
| 443 | if (error == ENOENT && (nd->nl_flags & NLC_CREATE)) |
| 444 | error = naccess(ncp, VCREATE, nd->nl_cred); |
| 445 | if (error == 0 && wasdotordotdot && (nd->nl_flags & NLC_DELETE)) |
| 446 | error = EINVAL; |
| 447 | } |
| 448 | |
| 449 | /* |
| 450 | * Early completion on error. |
| 451 | */ |
| 452 | if (error) { |
| 453 | cache_put(ncp); |
| 454 | break; |
| 455 | } |
| 456 | |
| 457 | /* |
| 458 | * If the element is a symlink and it is either not the last |
| 459 | * element or it is the last element and we are allowed to |
| 460 | * follow symlinks, resolve the symlink. |
| 461 | */ |
| 462 | if ((ncp->nc_flag & NCF_ISSYMLINK) && |
| 463 | (*ptr || (nd->nl_flags & NLC_FOLLOW)) |
| 464 | ) { |
| 465 | if (nd->nl_loopcnt++ >= MAXSYMLINKS) { |
| 466 | error = ELOOP; |
| 467 | cache_put(ncp); |
| 468 | break; |
| 469 | } |
| 470 | error = nreadsymlink(nd, ncp, &nlc); |
| 471 | cache_put(ncp); |
| 472 | if (error) |
| 473 | break; |
| 474 | |
| 475 | /* |
| 476 | * Concatenate trailing path elements onto the returned symlink. |
| 477 | * Note that if the path component (ptr) is not exhausted, it |
| 478 | * will being with a '/', so we do not have to add another one. |
| 479 | * |
| 480 | * The symlink may not be empty. |
| 481 | */ |
| 482 | len = strlen(ptr); |
| 483 | if (nlc.nlc_namelen == 0 || nlc.nlc_namelen + len >= MAXPATHLEN) { |
| 484 | error = nlc.nlc_namelen ? ENAMETOOLONG : ENOENT; |
| 485 | objcache_put(namei_oc, nlc.nlc_nameptr); |
| 486 | break; |
| 487 | } |
| 488 | bcopy(ptr, nlc.nlc_nameptr + nlc.nlc_namelen, len + 1); |
| 489 | if (nd->nl_flags & NLC_HASBUF) |
| 490 | objcache_put(namei_oc, nd->nl_path); |
| 491 | nd->nl_path = nlc.nlc_nameptr; |
| 492 | nd->nl_flags |= NLC_HASBUF; |
| 493 | ptr = nd->nl_path; |
| 494 | |
| 495 | /* |
| 496 | * Go back up to the top to resolve any initial '/'s in the |
| 497 | * symlink. |
| 498 | */ |
| 499 | continue; |
| 500 | } |
| 501 | |
| 502 | /* |
| 503 | * If the element is a directory and we are crossing a mount point, |
| 504 | * retrieve the root of the mounted filesystem from mnt_ncp and |
| 505 | * resolve it if necessary. |
| 506 | * |
| 507 | * XXX mnt_ncp should really be resolved in the mount code. |
| 508 | * NOTE! the normal nresolve() code cannot resolve mount point ncp's! |
| 509 | * |
| 510 | * XXX NOCROSSMOUNT |
| 511 | */ |
| 512 | while ((ncp->nc_flag & NCF_ISDIR) && ncp->nc_vp->v_mountedhere && |
| 513 | (nd->nl_flags & NLC_NOCROSSMOUNT) == 0 |
| 514 | ) { |
| 515 | struct mount *mp; |
| 516 | struct vnode *tdp; |
| 517 | |
| 518 | mp = ncp->nc_vp->v_mountedhere; |
| 519 | cache_put(ncp); |
| 520 | ncp = cache_get(mp->mnt_ncp); |
| 521 | |
| 522 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 523 | while (vfs_busy(mp, 0)) |
| 524 | ; |
| 525 | error = VFS_ROOT(mp, &tdp); |
| 526 | vfs_unbusy(mp); |
| 527 | if (error) |
| 528 | break; |
| 529 | cache_setvp(ncp, tdp); |
| 530 | vput(tdp); |
| 531 | } |
| 532 | } |
| 533 | if (error) { |
| 534 | cache_put(ncp); |
| 535 | break; |
| 536 | } |
| 537 | |
| 538 | /* |
| 539 | * Skip any slashes to get to the next element. If there |
| 540 | * are any slashes at all the current element must be a |
| 541 | * directory or, in the create case, intended to become a directory. |
| 542 | * If it isn't we break without incrementing ptr and fall through |
| 543 | * to the failure case below. |
| 544 | */ |
| 545 | while (*ptr == '/') { |
| 546 | if ((ncp->nc_flag & NCF_ISDIR) == 0 && |
| 547 | !(nd->nl_flags & NLC_WILLBEDIR) |
| 548 | ) { |
| 549 | break; |
| 550 | } |
| 551 | ++ptr; |
| 552 | } |
| 553 | |
| 554 | /* |
| 555 | * Continuation case: additional elements and the current |
| 556 | * element is a directory. |
| 557 | */ |
| 558 | if (*ptr && (ncp->nc_flag & NCF_ISDIR)) { |
| 559 | cache_drop(nd->nl_ncp); |
| 560 | cache_unlock(ncp); |
| 561 | nd->nl_ncp = ncp; |
| 562 | continue; |
| 563 | } |
| 564 | |
| 565 | /* |
| 566 | * Failure case: additional elements and the current element |
| 567 | * is not a directory |
| 568 | */ |
| 569 | if (*ptr) { |
| 570 | cache_put(ncp); |
| 571 | error = ENOTDIR; |
| 572 | break; |
| 573 | } |
| 574 | |
| 575 | /* |
| 576 | * Successful lookup of last element. |
| 577 | * |
| 578 | * Check directory permissions if a deletion is specified. |
| 579 | */ |
| 580 | if (*ptr == 0 && (nd->nl_flags & NLC_DELETE)) { |
| 581 | if ((error = naccess(ncp, VDELETE, nd->nl_cred)) != 0) { |
| 582 | cache_put(ncp); |
| 583 | break; |
| 584 | } |
| 585 | } |
| 586 | |
| 587 | /* |
| 588 | * Termination: no more elements. If NLC_CREATE was set the |
| 589 | * ncp may represent a negative hit (ncp->nc_error will be ENOENT), |
| 590 | * but we still return an error code of 0. |
| 591 | */ |
| 592 | cache_drop(nd->nl_ncp); |
| 593 | nd->nl_ncp = ncp; |
| 594 | nd->nl_flags |= NLC_NCPISLOCKED; |
| 595 | error = 0; |
| 596 | break; |
| 597 | } |
| 598 | return(error); |
| 599 | } |
| 600 | |
| 601 | /* |
| 602 | * Resolve a mount point's glue ncp. This ncp connects creates the illusion |
| 603 | * of continuity in the namecache tree by connecting the ncp related to the |
| 604 | * vnode under the mount to the ncp related to the mount's root vnode. |
| 605 | * |
| 606 | * If no error occured a locked, ref'd ncp is stored in *ncpp. |
| 607 | */ |
| 608 | int |
| 609 | nlookup_mp(struct mount *mp, struct namecache **ncpp) |
| 610 | { |
| 611 | struct namecache *ncp; |
| 612 | struct vnode *vp; |
| 613 | int error; |
| 614 | |
| 615 | error = 0; |
| 616 | ncp = mp->mnt_ncp; |
| 617 | cache_get(ncp); |
| 618 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 619 | while (vfs_busy(mp, 0)) |
| 620 | ; |
| 621 | error = VFS_ROOT(mp, &vp); |
| 622 | vfs_unbusy(mp); |
| 623 | if (error) { |
| 624 | cache_put(ncp); |
| 625 | ncp = NULL; |
| 626 | } else { |
| 627 | cache_setvp(ncp, vp); |
| 628 | vput(vp); |
| 629 | } |
| 630 | } |
| 631 | *ncpp = ncp; |
| 632 | return(error); |
| 633 | } |
| 634 | |
| 635 | /* |
| 636 | * Read the contents of a symlink, allocate a path buffer out of the |
| 637 | * namei_oc and initialize the supplied nlcomponent with the result. |
| 638 | * |
| 639 | * If an error occurs no buffer will be allocated or returned in the nlc. |
| 640 | */ |
| 641 | int |
| 642 | nreadsymlink(struct nlookupdata *nd, struct namecache *ncp, |
| 643 | struct nlcomponent *nlc) |
| 644 | { |
| 645 | struct vnode *vp; |
| 646 | struct iovec aiov; |
| 647 | struct uio auio; |
| 648 | int linklen; |
| 649 | int error; |
| 650 | char *cp; |
| 651 | |
| 652 | nlc->nlc_nameptr = NULL; |
| 653 | nlc->nlc_namelen = 0; |
| 654 | if (ncp->nc_vp == NULL) |
| 655 | return(ENOENT); |
| 656 | if ((error = cache_vget(ncp, nd->nl_cred, LK_SHARED, &vp)) != 0) |
| 657 | return(error); |
| 658 | cp = objcache_get(namei_oc, M_WAITOK); |
| 659 | aiov.iov_base = cp; |
| 660 | aiov.iov_len = MAXPATHLEN; |
| 661 | auio.uio_iov = &aiov; |
| 662 | auio.uio_iovcnt = 1; |
| 663 | auio.uio_offset = 0; |
| 664 | auio.uio_rw = UIO_READ; |
| 665 | auio.uio_segflg = UIO_SYSSPACE; |
| 666 | auio.uio_td = nd->nl_td; |
| 667 | auio.uio_resid = MAXPATHLEN - 1; |
| 668 | error = VOP_READLINK(vp, &auio, nd->nl_cred); |
| 669 | if (error) |
| 670 | goto fail; |
| 671 | linklen = MAXPATHLEN - 1 - auio.uio_resid; |
| 672 | if (varsym_enable) { |
| 673 | linklen = varsymreplace(cp, linklen, MAXPATHLEN - 1); |
| 674 | if (linklen < 0) { |
| 675 | error = ENAMETOOLONG; |
| 676 | goto fail; |
| 677 | } |
| 678 | } |
| 679 | cp[linklen] = 0; |
| 680 | nlc->nlc_nameptr = cp; |
| 681 | nlc->nlc_namelen = linklen; |
| 682 | vput(vp); |
| 683 | return(0); |
| 684 | fail: |
| 685 | objcache_put(namei_oc, cp); |
| 686 | vput(vp); |
| 687 | return(error); |
| 688 | } |
| 689 | |
| 690 | /* |
| 691 | * Check access [XXX cache vattr!] [XXX quota] |
| 692 | * |
| 693 | * Generally check the V* access bits from sys/vnode.h. All specified bits |
| 694 | * must pass for this function to return 0. |
| 695 | * |
| 696 | * If VCREATE is specified and the target ncp represents a non-existant |
| 697 | * file or dir, or if VDELETE is specified and the target exists, the parent |
| 698 | * directory is checked for VWRITE. If VEXCL is specified and the target |
| 699 | * ncp represents a positive hit, an error is returned. |
| 700 | * |
| 701 | * If VCREATE is not specified and the target does not exist (negative hit), |
| 702 | * ENOENT is returned. Note that nlookup() does not (and should not) return |
| 703 | * ENOENT for non-existant leafs. |
| 704 | * |
| 705 | * The passed ncp may or may not be locked. The caller should use a |
| 706 | * locked ncp on leaf lookups, especially for VCREATE, VDELETE, and VEXCL |
| 707 | * checks. |
| 708 | */ |
| 709 | int |
| 710 | naccess(struct namecache *ncp, int vmode, struct ucred *cred) |
| 711 | { |
| 712 | struct namecache *par; |
| 713 | struct vnode *vp; |
| 714 | struct vattr va; |
| 715 | int error; |
| 716 | |
| 717 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 718 | cache_lock(ncp); |
| 719 | cache_resolve(ncp, cred); |
| 720 | cache_unlock(ncp); |
| 721 | } |
| 722 | error = ncp->nc_error; |
| 723 | if (vmode & (VDELETE|VCREATE|VEXCL)) { |
| 724 | if (((vmode & VCREATE) && ncp->nc_vp == NULL) || |
| 725 | ((vmode & VDELETE) && ncp->nc_vp != NULL) |
| 726 | ) { |
| 727 | if ((par = ncp->nc_parent) == NULL) { |
| 728 | if (error != EAGAIN) |
| 729 | error = EINVAL; |
| 730 | } else { |
| 731 | cache_hold(par); |
| 732 | error = naccess(par, VWRITE, cred); |
| 733 | cache_drop(par); |
| 734 | } |
| 735 | } |
| 736 | if ((vmode & VEXCL) && ncp->nc_vp != NULL) |
| 737 | error = EEXIST; |
| 738 | } |
| 739 | if (error == 0) { |
| 740 | error = cache_vget(ncp, cred, LK_SHARED, &vp); |
| 741 | if (error == ENOENT) { |
| 742 | if (vmode & VCREATE) |
| 743 | error = 0; |
| 744 | } else if (error == 0) { |
| 745 | /* XXX cache the va in the namecache or in the vnode */ |
| 746 | if ((error = VOP_GETATTR(vp, &va)) == 0) { |
| 747 | if ((vmode & VWRITE) && vp->v_mount) { |
| 748 | if (vp->v_mount->mnt_flag & MNT_RDONLY) |
| 749 | error = EROFS; |
| 750 | } |
| 751 | } |
| 752 | vput(vp); |
| 753 | if (error == 0) |
| 754 | error = naccess_va(&va, vmode, cred); |
| 755 | } |
| 756 | } |
| 757 | return(error); |
| 758 | } |
| 759 | |
| 760 | /* |
| 761 | * Check the requested access against the given vattr using cred. |
| 762 | */ |
| 763 | int |
| 764 | naccess_va(struct vattr *va, int vmode, struct ucred *cred) |
| 765 | { |
| 766 | int i; |
| 767 | |
| 768 | /* |
| 769 | * Test the immutable bit for files, directories, and softlinks. |
| 770 | */ |
| 771 | if (vmode & (VWRITE|VDELETE)) { |
| 772 | if (va->va_type == VDIR || va->va_type == VLNK || va->va_type == VREG) { |
| 773 | if (va->va_flags & IMMUTABLE) |
| 774 | return (EPERM); |
| 775 | } |
| 776 | } |
| 777 | |
| 778 | /* |
| 779 | * root gets universal access |
| 780 | */ |
| 781 | if (cred->cr_uid == 0) |
| 782 | return(0); |
| 783 | |
| 784 | /* |
| 785 | * Check owner perms, group perms, and world perms |
| 786 | */ |
| 787 | vmode &= S_IRWXU; |
| 788 | if (cred->cr_uid == va->va_uid) { |
| 789 | if ((vmode & va->va_mode) != vmode) |
| 790 | return(EACCES); |
| 791 | return(0); |
| 792 | } |
| 793 | |
| 794 | vmode >>= 3; |
| 795 | for (i = 0; i < cred->cr_ngroups; ++i) { |
| 796 | if (va->va_gid == cred->cr_groups[i]) { |
| 797 | if ((vmode & va->va_mode) != vmode) |
| 798 | return(EACCES); |
| 799 | return(0); |
| 800 | } |
| 801 | } |
| 802 | |
| 803 | vmode >>= 3; |
| 804 | if ((vmode & va->va_mode) != vmode) |
| 805 | return(EACCES); |
| 806 | return(0); |
| 807 | } |
| 808 | |