xref: /openbmc/linux/fs/stat.c (revision ca79522c) 
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 path *path, struct kstat *stat)
41 {
42 	struct inode *inode = path->dentry->d_inode;
43 	int retval;
44 
45 	retval = security_inode_getattr(path->mnt, path->dentry);
46 	if (retval)
47 		return retval;
48 
49 	if (inode->i_op->getattr)
50 		return inode->i_op->getattr(path->mnt, path->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, stat);
65 		fdput(f);
66 	}
67 	return error;
68 }
69 EXPORT_SYMBOL(vfs_fstat);
70 
71 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
72 		int flag)
73 {
74 	struct path path;
75 	int error = -EINVAL;
76 	unsigned int lookup_flags = 0;
77 
78 	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
79 		      AT_EMPTY_PATH)) != 0)
80 		goto out;
81 
82 	if (!(flag & AT_SYMLINK_NOFOLLOW))
83 		lookup_flags |= LOOKUP_FOLLOW;
84 	if (flag & AT_EMPTY_PATH)
85 		lookup_flags |= LOOKUP_EMPTY;
86 retry:
87 	error = user_path_at(dfd, filename, lookup_flags, &path);
88 	if (error)
89 		goto out;
90 
91 	error = vfs_getattr(&path, stat);
92 	path_put(&path);
93 	if (retry_estale(error, lookup_flags)) {
94 		lookup_flags |= LOOKUP_REVAL;
95 		goto retry;
96 	}
97 out:
98 	return error;
99 }
100 EXPORT_SYMBOL(vfs_fstatat);
101 
102 int vfs_stat(const char __user *name, struct kstat *stat)
103 {
104 	return vfs_fstatat(AT_FDCWD, name, stat, 0);
105 }
106 EXPORT_SYMBOL(vfs_stat);
107 
108 int vfs_lstat(const char __user *name, struct kstat *stat)
109 {
110 	return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
111 }
112 EXPORT_SYMBOL(vfs_lstat);
113 
114 
115 #ifdef __ARCH_WANT_OLD_STAT
116 
117 /*
118  * For backward compatibility?  Maybe this should be moved
119  * into arch/i386 instead?
120  */
121 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
122 {
123 	static int warncount = 5;
124 	struct __old_kernel_stat tmp;
125 
126 	if (warncount > 0) {
127 		warncount--;
128 		printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
129 			current->comm);
130 	} else if (warncount < 0) {
131 		/* it's laughable, but... */
132 		warncount = 0;
133 	}
134 
135 	memset(&tmp, 0, sizeof(struct __old_kernel_stat));
136 	tmp.st_dev = old_encode_dev(stat->dev);
137 	tmp.st_ino = stat->ino;
138 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
139 		return -EOVERFLOW;
140 	tmp.st_mode = stat->mode;
141 	tmp.st_nlink = stat->nlink;
142 	if (tmp.st_nlink != stat->nlink)
143 		return -EOVERFLOW;
144 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
145 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
146 	tmp.st_rdev = old_encode_dev(stat->rdev);
147 #if BITS_PER_LONG == 32
148 	if (stat->size > MAX_NON_LFS)
149 		return -EOVERFLOW;
150 #endif
151 	tmp.st_size = stat->size;
152 	tmp.st_atime = stat->atime.tv_sec;
153 	tmp.st_mtime = stat->mtime.tv_sec;
154 	tmp.st_ctime = stat->ctime.tv_sec;
155 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
156 }
157 
158 SYSCALL_DEFINE2(stat, const char __user *, filename,
159 		struct __old_kernel_stat __user *, statbuf)
160 {
161 	struct kstat stat;
162 	int error;
163 
164 	error = vfs_stat(filename, &stat);
165 	if (error)
166 		return error;
167 
168 	return cp_old_stat(&stat, statbuf);
169 }
170 
171 SYSCALL_DEFINE2(lstat, const char __user *, filename,
172 		struct __old_kernel_stat __user *, statbuf)
173 {
174 	struct kstat stat;
175 	int error;
176 
177 	error = vfs_lstat(filename, &stat);
178 	if (error)
179 		return error;
180 
181 	return cp_old_stat(&stat, statbuf);
182 }
183 
184 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
185 {
186 	struct kstat stat;
187 	int error = vfs_fstat(fd, &stat);
188 
189 	if (!error)
190 		error = cp_old_stat(&stat, statbuf);
191 
192 	return error;
193 }
194 
195 #endif /* __ARCH_WANT_OLD_STAT */
196 
197 #if BITS_PER_LONG == 32
198 #  define choose_32_64(a,b) a
199 #else
200 #  define choose_32_64(a,b) b
201 #endif
202 
203 #define valid_dev(x)  choose_32_64(old_valid_dev,new_valid_dev)(x)
204 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
205 
206 #ifndef INIT_STRUCT_STAT_PADDING
207 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
208 #endif
209 
210 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
211 {
212 	struct stat tmp;
213 
214 	if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
215 		return -EOVERFLOW;
216 #if BITS_PER_LONG == 32
217 	if (stat->size > MAX_NON_LFS)
218 		return -EOVERFLOW;
219 #endif
220 
221 	INIT_STRUCT_STAT_PADDING(tmp);
222 	tmp.st_dev = encode_dev(stat->dev);
223 	tmp.st_ino = stat->ino;
224 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
225 		return -EOVERFLOW;
226 	tmp.st_mode = stat->mode;
227 	tmp.st_nlink = stat->nlink;
228 	if (tmp.st_nlink != stat->nlink)
229 		return -EOVERFLOW;
230 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
231 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
232 	tmp.st_rdev = encode_dev(stat->rdev);
233 	tmp.st_size = stat->size;
234 	tmp.st_atime = stat->atime.tv_sec;
235 	tmp.st_mtime = stat->mtime.tv_sec;
236 	tmp.st_ctime = stat->ctime.tv_sec;
237 #ifdef STAT_HAVE_NSEC
238 	tmp.st_atime_nsec = stat->atime.tv_nsec;
239 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
240 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
241 #endif
242 	tmp.st_blocks = stat->blocks;
243 	tmp.st_blksize = stat->blksize;
244 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
245 }
246 
247 SYSCALL_DEFINE2(newstat, const char __user *, filename,
248 		struct stat __user *, statbuf)
249 {
250 	struct kstat stat;
251 	int error = vfs_stat(filename, &stat);
252 
253 	if (error)
254 		return error;
255 	return cp_new_stat(&stat, statbuf);
256 }
257 
258 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
259 		struct stat __user *, statbuf)
260 {
261 	struct kstat stat;
262 	int error;
263 
264 	error = vfs_lstat(filename, &stat);
265 	if (error)
266 		return error;
267 
268 	return cp_new_stat(&stat, statbuf);
269 }
270 
271 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
272 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
273 		struct stat __user *, statbuf, int, flag)
274 {
275 	struct kstat stat;
276 	int error;
277 
278 	error = vfs_fstatat(dfd, filename, &stat, flag);
279 	if (error)
280 		return error;
281 	return cp_new_stat(&stat, statbuf);
282 }
283 #endif
284 
285 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
286 {
287 	struct kstat stat;
288 	int error = vfs_fstat(fd, &stat);
289 
290 	if (!error)
291 		error = cp_new_stat(&stat, statbuf);
292 
293 	return error;
294 }
295 
296 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
297 		char __user *, buf, int, bufsiz)
298 {
299 	struct path path;
300 	int error;
301 	int empty = 0;
302 	unsigned int lookup_flags = LOOKUP_EMPTY;
303 
304 	if (bufsiz <= 0)
305 		return -EINVAL;
306 
307 retry:
308 	error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
309 	if (!error) {
310 		struct inode *inode = path.dentry->d_inode;
311 
312 		error = empty ? -ENOENT : -EINVAL;
313 		if (inode->i_op->readlink) {
314 			error = security_inode_readlink(path.dentry);
315 			if (!error) {
316 				touch_atime(&path);
317 				error = inode->i_op->readlink(path.dentry,
318 							      buf, bufsiz);
319 			}
320 		}
321 		path_put(&path);
322 		if (retry_estale(error, lookup_flags)) {
323 			lookup_flags |= LOOKUP_REVAL;
324 			goto retry;
325 		}
326 	}
327 	return error;
328 }
329 
330 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
331 		int, bufsiz)
332 {
333 	return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
334 }
335 
336 
337 /* ---------- LFS-64 ----------- */
338 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
339 
340 #ifndef INIT_STRUCT_STAT64_PADDING
341 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
342 #endif
343 
344 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
345 {
346 	struct stat64 tmp;
347 
348 	INIT_STRUCT_STAT64_PADDING(tmp);
349 #ifdef CONFIG_MIPS
350 	/* mips has weird padding, so we don't get 64 bits there */
351 	if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
352 		return -EOVERFLOW;
353 	tmp.st_dev = new_encode_dev(stat->dev);
354 	tmp.st_rdev = new_encode_dev(stat->rdev);
355 #else
356 	tmp.st_dev = huge_encode_dev(stat->dev);
357 	tmp.st_rdev = huge_encode_dev(stat->rdev);
358 #endif
359 	tmp.st_ino = stat->ino;
360 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
361 		return -EOVERFLOW;
362 #ifdef STAT64_HAS_BROKEN_ST_INO
363 	tmp.__st_ino = stat->ino;
364 #endif
365 	tmp.st_mode = stat->mode;
366 	tmp.st_nlink = stat->nlink;
367 	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
368 	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
369 	tmp.st_atime = stat->atime.tv_sec;
370 	tmp.st_atime_nsec = stat->atime.tv_nsec;
371 	tmp.st_mtime = stat->mtime.tv_sec;
372 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
373 	tmp.st_ctime = stat->ctime.tv_sec;
374 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
375 	tmp.st_size = stat->size;
376 	tmp.st_blocks = stat->blocks;
377 	tmp.st_blksize = stat->blksize;
378 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
379 }
380 
381 SYSCALL_DEFINE2(stat64, const char __user *, filename,
382 		struct stat64 __user *, statbuf)
383 {
384 	struct kstat stat;
385 	int error = vfs_stat(filename, &stat);
386 
387 	if (!error)
388 		error = cp_new_stat64(&stat, statbuf);
389 
390 	return error;
391 }
392 
393 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
394 		struct stat64 __user *, statbuf)
395 {
396 	struct kstat stat;
397 	int error = vfs_lstat(filename, &stat);
398 
399 	if (!error)
400 		error = cp_new_stat64(&stat, statbuf);
401 
402 	return error;
403 }
404 
405 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
406 {
407 	struct kstat stat;
408 	int error = vfs_fstat(fd, &stat);
409 
410 	if (!error)
411 		error = cp_new_stat64(&stat, statbuf);
412 
413 	return error;
414 }
415 
416 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
417 		struct stat64 __user *, statbuf, int, flag)
418 {
419 	struct kstat stat;
420 	int error;
421 
422 	error = vfs_fstatat(dfd, filename, &stat, flag);
423 	if (error)
424 		return error;
425 	return cp_new_stat64(&stat, statbuf);
426 }
427 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
428 
429 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
430 void __inode_add_bytes(struct inode *inode, loff_t bytes)
431 {
432 	inode->i_blocks += bytes >> 9;
433 	bytes &= 511;
434 	inode->i_bytes += bytes;
435 	if (inode->i_bytes >= 512) {
436 		inode->i_blocks++;
437 		inode->i_bytes -= 512;
438 	}
439 }
440 
441 void inode_add_bytes(struct inode *inode, loff_t bytes)
442 {
443 	spin_lock(&inode->i_lock);
444 	__inode_add_bytes(inode, bytes);
445 	spin_unlock(&inode->i_lock);
446 }
447 
448 EXPORT_SYMBOL(inode_add_bytes);
449 
450 void inode_sub_bytes(struct inode *inode, loff_t bytes)
451 {
452 	spin_lock(&inode->i_lock);
453 	inode->i_blocks -= bytes >> 9;
454 	bytes &= 511;
455 	if (inode->i_bytes < bytes) {
456 		inode->i_blocks--;
457 		inode->i_bytes += 512;
458 	}
459 	inode->i_bytes -= bytes;
460 	spin_unlock(&inode->i_lock);
461 }
462 
463 EXPORT_SYMBOL(inode_sub_bytes);
464 
465 loff_t inode_get_bytes(struct inode *inode)
466 {
467 	loff_t ret;
468 
469 	spin_lock(&inode->i_lock);
470 	ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
471 	spin_unlock(&inode->i_lock);
472 	return ret;
473 }
474 
475 EXPORT_SYMBOL(inode_get_bytes);
476 
477 void inode_set_bytes(struct inode *inode, loff_t bytes)
478 {
479 	/* Caller is here responsible for sufficient locking
480 	 * (ie. inode->i_lock) */
481 	inode->i_blocks = bytes >> 9;
482 	inode->i_bytes = bytes & 511;
483 }
484 
485 EXPORT_SYMBOL(inode_set_bytes);
486