xref: /linux/fs/stat.c (revision 0d456bad36d42d16022be045c8a53ddbb59ee478) 
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 <asm/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 int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
41 {
42 	struct inode *inode = dentry->d_inode;
43 	int retval;
44 
45 	retval = security_inode_getattr(mnt, dentry);
46 	if (retval)
47 		return retval;
48 
49 	if (inode->i_op->getattr)
50 		return inode->i_op->getattr(mnt, dentry, stat);
51 
52 	generic_fillattr(inode, stat);
53 	return 0;
54 }
55 
56 EXPORT_SYMBOL(vfs_getattr);
57 
58 int vfs_fstat(unsigned int fd, struct kstat *stat)
59 {
60 	struct fd f = fdget_raw(fd);
61 	int error = -EBADF;
62 
63 	if (f.file) {
64 		error = vfs_getattr(f.file->f_path.mnt, f.file->f_path.dentry,
65 				    stat);
66 		fdput(f);
67 	}
68 	return error;
69 }
70 EXPORT_SYMBOL(vfs_fstat);
71 
72 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
73 		int flag)
74 {
75 	struct path path;
76 	int error = -EINVAL;
77 	int lookup_flags = 0;
78 
79 	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
80 		      AT_EMPTY_PATH)) != 0)
81 		goto out;
82 
83 	if (!(flag & AT_SYMLINK_NOFOLLOW))
84 		lookup_flags |= LOOKUP_FOLLOW;
85 	if (flag & AT_EMPTY_PATH)
86 		lookup_flags |= LOOKUP_EMPTY;
87 
88 	error = user_path_at(dfd, filename, lookup_flags, &path);
89 	if (error)
90 		goto out;
91 
92 	error = vfs_getattr(path.mnt, path.dentry, stat);
93 	path_put(&path);
94 out:
95 	return error;
96 }
97 EXPORT_SYMBOL(vfs_fstatat);
98 
99 int vfs_stat(const char __user *name, struct kstat *stat)
100 {
101 	return vfs_fstatat(AT_FDCWD, name, stat, 0);
102 }
103 EXPORT_SYMBOL(vfs_stat);
104 
105 int vfs_lstat(const char __user *name, struct kstat *stat)
106 {
107 	return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
108 }
109 EXPORT_SYMBOL(vfs_lstat);
110 
111 
112 #ifdef __ARCH_WANT_OLD_STAT
113 
114 /*
115  * For backward compatibility?  Maybe this should be moved
116  * into arch/i386 instead?
117  */
118 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
119 {
120 	static int warncount = 5;
121 	struct __old_kernel_stat tmp;
122 
123 	if (warncount > 0) {
124 		warncount--;
125 		printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
126 			current->comm);
127 	} else if (warncount < 0) {
128 		/* it's laughable, but... */
129 		warncount = 0;
130 	}
131 
132 	memset(&tmp, 0, sizeof(struct __old_kernel_stat));
133 	tmp.st_dev = old_encode_dev(stat->dev);
134 	tmp.st_ino = stat->ino;
135 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
136 		return -EOVERFLOW;
137 	tmp.st_mode = stat->mode;
138 	tmp.st_nlink = stat->nlink;
139 	if (tmp.st_nlink != stat->nlink)
140 		return -EOVERFLOW;
141 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
142 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
143 	tmp.st_rdev = old_encode_dev(stat->rdev);
144 #if BITS_PER_LONG == 32
145 	if (stat->size > MAX_NON_LFS)
146 		return -EOVERFLOW;
147 #endif
148 	tmp.st_size = stat->size;
149 	tmp.st_atime = stat->atime.tv_sec;
150 	tmp.st_mtime = stat->mtime.tv_sec;
151 	tmp.st_ctime = stat->ctime.tv_sec;
152 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
153 }
154 
155 SYSCALL_DEFINE2(stat, const char __user *, filename,
156 		struct __old_kernel_stat __user *, statbuf)
157 {
158 	struct kstat stat;
159 	int error;
160 
161 	error = vfs_stat(filename, &stat);
162 	if (error)
163 		return error;
164 
165 	return cp_old_stat(&stat, statbuf);
166 }
167 
168 SYSCALL_DEFINE2(lstat, const char __user *, filename,
169 		struct __old_kernel_stat __user *, statbuf)
170 {
171 	struct kstat stat;
172 	int error;
173 
174 	error = vfs_lstat(filename, &stat);
175 	if (error)
176 		return error;
177 
178 	return cp_old_stat(&stat, statbuf);
179 }
180 
181 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
182 {
183 	struct kstat stat;
184 	int error = vfs_fstat(fd, &stat);
185 
186 	if (!error)
187 		error = cp_old_stat(&stat, statbuf);
188 
189 	return error;
190 }
191 
192 #endif /* __ARCH_WANT_OLD_STAT */
193 
194 #if BITS_PER_LONG == 32
195 #  define choose_32_64(a,b) a
196 #else
197 #  define choose_32_64(a,b) b
198 #endif
199 
200 #define valid_dev(x)  choose_32_64(old_valid_dev,new_valid_dev)(x)
201 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
202 
203 #ifndef INIT_STRUCT_STAT_PADDING
204 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
205 #endif
206 
207 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
208 {
209 	struct stat tmp;
210 
211 	if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
212 		return -EOVERFLOW;
213 #if BITS_PER_LONG == 32
214 	if (stat->size > MAX_NON_LFS)
215 		return -EOVERFLOW;
216 #endif
217 
218 	INIT_STRUCT_STAT_PADDING(tmp);
219 	tmp.st_dev = encode_dev(stat->dev);
220 	tmp.st_ino = stat->ino;
221 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
222 		return -EOVERFLOW;
223 	tmp.st_mode = stat->mode;
224 	tmp.st_nlink = stat->nlink;
225 	if (tmp.st_nlink != stat->nlink)
226 		return -EOVERFLOW;
227 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
228 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
229 	tmp.st_rdev = encode_dev(stat->rdev);
230 	tmp.st_size = stat->size;
231 	tmp.st_atime = stat->atime.tv_sec;
232 	tmp.st_mtime = stat->mtime.tv_sec;
233 	tmp.st_ctime = stat->ctime.tv_sec;
234 #ifdef STAT_HAVE_NSEC
235 	tmp.st_atime_nsec = stat->atime.tv_nsec;
236 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
237 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
238 #endif
239 	tmp.st_blocks = stat->blocks;
240 	tmp.st_blksize = stat->blksize;
241 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
242 }
243 
244 SYSCALL_DEFINE2(newstat, const char __user *, filename,
245 		struct stat __user *, statbuf)
246 {
247 	struct kstat stat;
248 	int error = vfs_stat(filename, &stat);
249 
250 	if (error)
251 		return error;
252 	return cp_new_stat(&stat, statbuf);
253 }
254 
255 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
256 		struct stat __user *, statbuf)
257 {
258 	struct kstat stat;
259 	int error;
260 
261 	error = vfs_lstat(filename, &stat);
262 	if (error)
263 		return error;
264 
265 	return cp_new_stat(&stat, statbuf);
266 }
267 
268 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
269 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
270 		struct stat __user *, statbuf, int, flag)
271 {
272 	struct kstat stat;
273 	int error;
274 
275 	error = vfs_fstatat(dfd, filename, &stat, flag);
276 	if (error)
277 		return error;
278 	return cp_new_stat(&stat, statbuf);
279 }
280 #endif
281 
282 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
283 {
284 	struct kstat stat;
285 	int error = vfs_fstat(fd, &stat);
286 
287 	if (!error)
288 		error = cp_new_stat(&stat, statbuf);
289 
290 	return error;
291 }
292 
293 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
294 		char __user *, buf, int, bufsiz)
295 {
296 	struct path path;
297 	int error;
298 	int empty = 0;
299 
300 	if (bufsiz <= 0)
301 		return -EINVAL;
302 
303 	error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
304 	if (!error) {
305 		struct inode *inode = path.dentry->d_inode;
306 
307 		error = empty ? -ENOENT : -EINVAL;
308 		if (inode->i_op->readlink) {
309 			error = security_inode_readlink(path.dentry);
310 			if (!error) {
311 				touch_atime(&path);
312 				error = inode->i_op->readlink(path.dentry,
313 							      buf, bufsiz);
314 			}
315 		}
316 		path_put(&path);
317 	}
318 	return error;
319 }
320 
321 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
322 		int, bufsiz)
323 {
324 	return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
325 }
326 
327 
328 /* ---------- LFS-64 ----------- */
329 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
330 
331 #ifndef INIT_STRUCT_STAT64_PADDING
332 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
333 #endif
334 
335 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
336 {
337 	struct stat64 tmp;
338 
339 	INIT_STRUCT_STAT64_PADDING(tmp);
340 #ifdef CONFIG_MIPS
341 	/* mips has weird padding, so we don't get 64 bits there */
342 	if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
343 		return -EOVERFLOW;
344 	tmp.st_dev = new_encode_dev(stat->dev);
345 	tmp.st_rdev = new_encode_dev(stat->rdev);
346 #else
347 	tmp.st_dev = huge_encode_dev(stat->dev);
348 	tmp.st_rdev = huge_encode_dev(stat->rdev);
349 #endif
350 	tmp.st_ino = stat->ino;
351 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
352 		return -EOVERFLOW;
353 #ifdef STAT64_HAS_BROKEN_ST_INO
354 	tmp.__st_ino = stat->ino;
355 #endif
356 	tmp.st_mode = stat->mode;
357 	tmp.st_nlink = stat->nlink;
358 	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
359 	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
360 	tmp.st_atime = stat->atime.tv_sec;
361 	tmp.st_atime_nsec = stat->atime.tv_nsec;
362 	tmp.st_mtime = stat->mtime.tv_sec;
363 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
364 	tmp.st_ctime = stat->ctime.tv_sec;
365 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
366 	tmp.st_size = stat->size;
367 	tmp.st_blocks = stat->blocks;
368 	tmp.st_blksize = stat->blksize;
369 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
370 }
371 
372 SYSCALL_DEFINE2(stat64, const char __user *, filename,
373 		struct stat64 __user *, statbuf)
374 {
375 	struct kstat stat;
376 	int error = vfs_stat(filename, &stat);
377 
378 	if (!error)
379 		error = cp_new_stat64(&stat, statbuf);
380 
381 	return error;
382 }
383 
384 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
385 		struct stat64 __user *, statbuf)
386 {
387 	struct kstat stat;
388 	int error = vfs_lstat(filename, &stat);
389 
390 	if (!error)
391 		error = cp_new_stat64(&stat, statbuf);
392 
393 	return error;
394 }
395 
396 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
397 {
398 	struct kstat stat;
399 	int error = vfs_fstat(fd, &stat);
400 
401 	if (!error)
402 		error = cp_new_stat64(&stat, statbuf);
403 
404 	return error;
405 }
406 
407 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
408 		struct stat64 __user *, statbuf, int, flag)
409 {
410 	struct kstat stat;
411 	int error;
412 
413 	error = vfs_fstatat(dfd, filename, &stat, flag);
414 	if (error)
415 		return error;
416 	return cp_new_stat64(&stat, statbuf);
417 }
418 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
419 
420 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
421 void __inode_add_bytes(struct inode *inode, loff_t bytes)
422 {
423 	inode->i_blocks += bytes >> 9;
424 	bytes &= 511;
425 	inode->i_bytes += bytes;
426 	if (inode->i_bytes >= 512) {
427 		inode->i_blocks++;
428 		inode->i_bytes -= 512;
429 	}
430 }
431 
432 void inode_add_bytes(struct inode *inode, loff_t bytes)
433 {
434 	spin_lock(&inode->i_lock);
435 	__inode_add_bytes(inode, bytes);
436 	spin_unlock(&inode->i_lock);
437 }
438 
439 EXPORT_SYMBOL(inode_add_bytes);
440 
441 void inode_sub_bytes(struct inode *inode, loff_t bytes)
442 {
443 	spin_lock(&inode->i_lock);
444 	inode->i_blocks -= bytes >> 9;
445 	bytes &= 511;
446 	if (inode->i_bytes < bytes) {
447 		inode->i_blocks--;
448 		inode->i_bytes += 512;
449 	}
450 	inode->i_bytes -= bytes;
451 	spin_unlock(&inode->i_lock);
452 }
453 
454 EXPORT_SYMBOL(inode_sub_bytes);
455 
456 loff_t inode_get_bytes(struct inode *inode)
457 {
458 	loff_t ret;
459 
460 	spin_lock(&inode->i_lock);
461 	ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
462 	spin_unlock(&inode->i_lock);
463 	return ret;
464 }
465 
466 EXPORT_SYMBOL(inode_get_bytes);
467 
468 void inode_set_bytes(struct inode *inode, loff_t bytes)
469 {
470 	/* Caller is here responsible for sufficient locking
471 	 * (ie. inode->i_lock) */
472 	inode->i_blocks = bytes >> 9;
473 	inode->i_bytes = bytes & 511;
474 }
475 
476 EXPORT_SYMBOL(inode_set_bytes);
477