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Linux/fs/stat.c

  1 /*
  2  *  linux/fs/stat.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  */
  6 
  7 #include <linux/export.h>
  8 #include <linux/mm.h>
  9 #include <linux/errno.h>
 10 #include <linux/file.h>
 11 #include <linux/highuid.h>
 12 #include <linux/fs.h>
 13 #include <linux/namei.h>
 14 #include <linux/security.h>
 15 #include <linux/syscalls.h>
 16 #include <linux/pagemap.h>
 17 
 18 #include <linux/uaccess.h>
 19 #include <asm/unistd.h>
 20 
 21 void generic_fillattr(struct inode *inode, struct kstat *stat)
 22 {
 23         stat->dev = inode->i_sb->s_dev;
 24         stat->ino = inode->i_ino;
 25         stat->mode = inode->i_mode;
 26         stat->nlink = inode->i_nlink;
 27         stat->uid = inode->i_uid;
 28         stat->gid = inode->i_gid;
 29         stat->rdev = inode->i_rdev;
 30         stat->size = i_size_read(inode);
 31         stat->atime = inode->i_atime;
 32         stat->mtime = inode->i_mtime;
 33         stat->ctime = inode->i_ctime;
 34         stat->blksize = (1 << inode->i_blkbits);
 35         stat->blocks = inode->i_blocks;
 36 }
 37 
 38 EXPORT_SYMBOL(generic_fillattr);
 39 
 40 /**
 41  * vfs_getattr_nosec - getattr without security checks
 42  * @path: file to get attributes from
 43  * @stat: structure to return attributes in
 44  *
 45  * Get attributes without calling security_inode_getattr.
 46  *
 47  * Currently the only caller other than vfs_getattr is internal to the
 48  * filehandle lookup code, which uses only the inode number and returns
 49  * no attributes to any user.  Any other code probably wants
 50  * vfs_getattr.
 51  */
 52 int vfs_getattr_nosec(struct path *path, struct kstat *stat)
 53 {
 54         struct inode *inode = d_backing_inode(path->dentry);
 55 
 56         if (inode->i_op->getattr)
 57                 return inode->i_op->getattr(path->mnt, path->dentry, stat);
 58 
 59         generic_fillattr(inode, stat);
 60         return 0;
 61 }
 62 
 63 EXPORT_SYMBOL(vfs_getattr_nosec);
 64 
 65 int vfs_getattr(struct path *path, struct kstat *stat)
 66 {
 67         int retval;
 68 
 69         retval = security_inode_getattr(path);
 70         if (retval)
 71                 return retval;
 72         return vfs_getattr_nosec(path, stat);
 73 }
 74 
 75 EXPORT_SYMBOL(vfs_getattr);
 76 
 77 int vfs_fstat(unsigned int fd, struct kstat *stat)
 78 {
 79         struct fd f = fdget_raw(fd);
 80         int error = -EBADF;
 81 
 82         if (f.file) {
 83                 error = vfs_getattr(&f.file->f_path, stat);
 84                 fdput(f);
 85         }
 86         return error;
 87 }
 88 EXPORT_SYMBOL(vfs_fstat);
 89 
 90 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 91                 int flag)
 92 {
 93         struct path path;
 94         int error = -EINVAL;
 95         unsigned int lookup_flags = 0;
 96 
 97         if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 98                       AT_EMPTY_PATH)) != 0)
 99                 goto out;
100 
101         if (!(flag & AT_SYMLINK_NOFOLLOW))
102                 lookup_flags |= LOOKUP_FOLLOW;
103         if (flag & AT_EMPTY_PATH)
104                 lookup_flags |= LOOKUP_EMPTY;
105 retry:
106         error = user_path_at(dfd, filename, lookup_flags, &path);
107         if (error)
108                 goto out;
109 
110         error = vfs_getattr(&path, stat);
111         path_put(&path);
112         if (retry_estale(error, lookup_flags)) {
113                 lookup_flags |= LOOKUP_REVAL;
114                 goto retry;
115         }
116 out:
117         return error;
118 }
119 EXPORT_SYMBOL(vfs_fstatat);
120 
121 int vfs_stat(const char __user *name, struct kstat *stat)
122 {
123         return vfs_fstatat(AT_FDCWD, name, stat, 0);
124 }
125 EXPORT_SYMBOL(vfs_stat);
126 
127 int vfs_lstat(const char __user *name, struct kstat *stat)
128 {
129         return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
130 }
131 EXPORT_SYMBOL(vfs_lstat);
132 
133 
134 #ifdef __ARCH_WANT_OLD_STAT
135 
136 /*
137  * For backward compatibility?  Maybe this should be moved
138  * into arch/i386 instead?
139  */
140 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
141 {
142         static int warncount = 5;
143         struct __old_kernel_stat tmp;
144         
145         if (warncount > 0) {
146                 warncount--;
147                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
148                         current->comm);
149         } else if (warncount < 0) {
150                 /* it's laughable, but... */
151                 warncount = 0;
152         }
153 
154         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
155         tmp.st_dev = old_encode_dev(stat->dev);
156         tmp.st_ino = stat->ino;
157         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
158                 return -EOVERFLOW;
159         tmp.st_mode = stat->mode;
160         tmp.st_nlink = stat->nlink;
161         if (tmp.st_nlink != stat->nlink)
162                 return -EOVERFLOW;
163         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
164         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
165         tmp.st_rdev = old_encode_dev(stat->rdev);
166 #if BITS_PER_LONG == 32
167         if (stat->size > MAX_NON_LFS)
168                 return -EOVERFLOW;
169 #endif  
170         tmp.st_size = stat->size;
171         tmp.st_atime = stat->atime.tv_sec;
172         tmp.st_mtime = stat->mtime.tv_sec;
173         tmp.st_ctime = stat->ctime.tv_sec;
174         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
175 }
176 
177 SYSCALL_DEFINE2(stat, const char __user *, filename,
178                 struct __old_kernel_stat __user *, statbuf)
179 {
180         struct kstat stat;
181         int error;
182 
183         error = vfs_stat(filename, &stat);
184         if (error)
185                 return error;
186 
187         return cp_old_stat(&stat, statbuf);
188 }
189 
190 SYSCALL_DEFINE2(lstat, const char __user *, filename,
191                 struct __old_kernel_stat __user *, statbuf)
192 {
193         struct kstat stat;
194         int error;
195 
196         error = vfs_lstat(filename, &stat);
197         if (error)
198                 return error;
199 
200         return cp_old_stat(&stat, statbuf);
201 }
202 
203 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
204 {
205         struct kstat stat;
206         int error = vfs_fstat(fd, &stat);
207 
208         if (!error)
209                 error = cp_old_stat(&stat, statbuf);
210 
211         return error;
212 }
213 
214 #endif /* __ARCH_WANT_OLD_STAT */
215 
216 #if BITS_PER_LONG == 32
217 #  define choose_32_64(a,b) a
218 #else
219 #  define choose_32_64(a,b) b
220 #endif
221 
222 #define valid_dev(x)  choose_32_64(old_valid_dev(x),true)
223 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
224 
225 #ifndef INIT_STRUCT_STAT_PADDING
226 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
227 #endif
228 
229 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
230 {
231         struct stat tmp;
232 
233         if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
234                 return -EOVERFLOW;
235 #if BITS_PER_LONG == 32
236         if (stat->size > MAX_NON_LFS)
237                 return -EOVERFLOW;
238 #endif
239 
240         INIT_STRUCT_STAT_PADDING(tmp);
241         tmp.st_dev = encode_dev(stat->dev);
242         tmp.st_ino = stat->ino;
243         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
244                 return -EOVERFLOW;
245         tmp.st_mode = stat->mode;
246         tmp.st_nlink = stat->nlink;
247         if (tmp.st_nlink != stat->nlink)
248                 return -EOVERFLOW;
249         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
250         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
251         tmp.st_rdev = encode_dev(stat->rdev);
252         tmp.st_size = stat->size;
253         tmp.st_atime = stat->atime.tv_sec;
254         tmp.st_mtime = stat->mtime.tv_sec;
255         tmp.st_ctime = stat->ctime.tv_sec;
256 #ifdef STAT_HAVE_NSEC
257         tmp.st_atime_nsec = stat->atime.tv_nsec;
258         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
259         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
260 #endif
261         tmp.st_blocks = stat->blocks;
262         tmp.st_blksize = stat->blksize;
263         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
264 }
265 
266 SYSCALL_DEFINE2(newstat, const char __user *, filename,
267                 struct stat __user *, statbuf)
268 {
269         struct kstat stat;
270         int error = vfs_stat(filename, &stat);
271 
272         if (error)
273                 return error;
274         return cp_new_stat(&stat, statbuf);
275 }
276 
277 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
278                 struct stat __user *, statbuf)
279 {
280         struct kstat stat;
281         int error;
282 
283         error = vfs_lstat(filename, &stat);
284         if (error)
285                 return error;
286 
287         return cp_new_stat(&stat, statbuf);
288 }
289 
290 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
291 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
292                 struct stat __user *, statbuf, int, flag)
293 {
294         struct kstat stat;
295         int error;
296 
297         error = vfs_fstatat(dfd, filename, &stat, flag);
298         if (error)
299                 return error;
300         return cp_new_stat(&stat, statbuf);
301 }
302 #endif
303 
304 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
305 {
306         struct kstat stat;
307         int error = vfs_fstat(fd, &stat);
308 
309         if (!error)
310                 error = cp_new_stat(&stat, statbuf);
311 
312         return error;
313 }
314 
315 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
316                 char __user *, buf, int, bufsiz)
317 {
318         struct path path;
319         int error;
320         int empty = 0;
321         unsigned int lookup_flags = LOOKUP_EMPTY;
322 
323         if (bufsiz <= 0)
324                 return -EINVAL;
325 
326 retry:
327         error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
328         if (!error) {
329                 struct inode *inode = d_backing_inode(path.dentry);
330 
331                 error = empty ? -ENOENT : -EINVAL;
332                 /*
333                  * AFS mountpoints allow readlink(2) but are not symlinks
334                  */
335                 if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
336                         error = security_inode_readlink(path.dentry);
337                         if (!error) {
338                                 touch_atime(&path);
339                                 error = vfs_readlink(path.dentry, buf, bufsiz);
340                         }
341                 }
342                 path_put(&path);
343                 if (retry_estale(error, lookup_flags)) {
344                         lookup_flags |= LOOKUP_REVAL;
345                         goto retry;
346                 }
347         }
348         return error;
349 }
350 
351 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
352                 int, bufsiz)
353 {
354         return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
355 }
356 
357 
358 /* ---------- LFS-64 ----------- */
359 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
360 
361 #ifndef INIT_STRUCT_STAT64_PADDING
362 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
363 #endif
364 
365 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
366 {
367         struct stat64 tmp;
368 
369         INIT_STRUCT_STAT64_PADDING(tmp);
370 #ifdef CONFIG_MIPS
371         /* mips has weird padding, so we don't get 64 bits there */
372         tmp.st_dev = new_encode_dev(stat->dev);
373         tmp.st_rdev = new_encode_dev(stat->rdev);
374 #else
375         tmp.st_dev = huge_encode_dev(stat->dev);
376         tmp.st_rdev = huge_encode_dev(stat->rdev);
377 #endif
378         tmp.st_ino = stat->ino;
379         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
380                 return -EOVERFLOW;
381 #ifdef STAT64_HAS_BROKEN_ST_INO
382         tmp.__st_ino = stat->ino;
383 #endif
384         tmp.st_mode = stat->mode;
385         tmp.st_nlink = stat->nlink;
386         tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
387         tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
388         tmp.st_atime = stat->atime.tv_sec;
389         tmp.st_atime_nsec = stat->atime.tv_nsec;
390         tmp.st_mtime = stat->mtime.tv_sec;
391         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
392         tmp.st_ctime = stat->ctime.tv_sec;
393         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
394         tmp.st_size = stat->size;
395         tmp.st_blocks = stat->blocks;
396         tmp.st_blksize = stat->blksize;
397         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
398 }
399 
400 SYSCALL_DEFINE2(stat64, const char __user *, filename,
401                 struct stat64 __user *, statbuf)
402 {
403         struct kstat stat;
404         int error = vfs_stat(filename, &stat);
405 
406         if (!error)
407                 error = cp_new_stat64(&stat, statbuf);
408 
409         return error;
410 }
411 
412 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
413                 struct stat64 __user *, statbuf)
414 {
415         struct kstat stat;
416         int error = vfs_lstat(filename, &stat);
417 
418         if (!error)
419                 error = cp_new_stat64(&stat, statbuf);
420 
421         return error;
422 }
423 
424 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
425 {
426         struct kstat stat;
427         int error = vfs_fstat(fd, &stat);
428 
429         if (!error)
430                 error = cp_new_stat64(&stat, statbuf);
431 
432         return error;
433 }
434 
435 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
436                 struct stat64 __user *, statbuf, int, flag)
437 {
438         struct kstat stat;
439         int error;
440 
441         error = vfs_fstatat(dfd, filename, &stat, flag);
442         if (error)
443                 return error;
444         return cp_new_stat64(&stat, statbuf);
445 }
446 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
447 
448 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
449 void __inode_add_bytes(struct inode *inode, loff_t bytes)
450 {
451         inode->i_blocks += bytes >> 9;
452         bytes &= 511;
453         inode->i_bytes += bytes;
454         if (inode->i_bytes >= 512) {
455                 inode->i_blocks++;
456                 inode->i_bytes -= 512;
457         }
458 }
459 
460 void inode_add_bytes(struct inode *inode, loff_t bytes)
461 {
462         spin_lock(&inode->i_lock);
463         __inode_add_bytes(inode, bytes);
464         spin_unlock(&inode->i_lock);
465 }
466 
467 EXPORT_SYMBOL(inode_add_bytes);
468 
469 void __inode_sub_bytes(struct inode *inode, loff_t bytes)
470 {
471         inode->i_blocks -= bytes >> 9;
472         bytes &= 511;
473         if (inode->i_bytes < bytes) {
474                 inode->i_blocks--;
475                 inode->i_bytes += 512;
476         }
477         inode->i_bytes -= bytes;
478 }
479 
480 EXPORT_SYMBOL(__inode_sub_bytes);
481 
482 void inode_sub_bytes(struct inode *inode, loff_t bytes)
483 {
484         spin_lock(&inode->i_lock);
485         __inode_sub_bytes(inode, bytes);
486         spin_unlock(&inode->i_lock);
487 }
488 
489 EXPORT_SYMBOL(inode_sub_bytes);
490 
491 loff_t inode_get_bytes(struct inode *inode)
492 {
493         loff_t ret;
494 
495         spin_lock(&inode->i_lock);
496         ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
497         spin_unlock(&inode->i_lock);
498         return ret;
499 }
500 
501 EXPORT_SYMBOL(inode_get_bytes);
502 
503 void inode_set_bytes(struct inode *inode, loff_t bytes)
504 {
505         /* Caller is here responsible for sufficient locking
506          * (ie. inode->i_lock) */
507         inode->i_blocks = bytes >> 9;
508         inode->i_bytes = bytes & 511;
509 }
510 
511 EXPORT_SYMBOL(inode_set_bytes);
512 

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