xref: /openbmc/linux/fs/stat.c (revision d0b73b48) 
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 	unsigned 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 retry:
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 	if (retry_estale(error, lookup_flags)) {
95 		lookup_flags |= LOOKUP_REVAL;
96 		goto retry;
97 	}
98 out:
99 	return error;
100 }
101 EXPORT_SYMBOL(vfs_fstatat);
102 
103 int vfs_stat(const char __user *name, struct kstat *stat)
104 {
105 	return vfs_fstatat(AT_FDCWD, name, stat, 0);
106 }
107 EXPORT_SYMBOL(vfs_stat);
108 
109 int vfs_lstat(const char __user *name, struct kstat *stat)
110 {
111 	return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
112 }
113 EXPORT_SYMBOL(vfs_lstat);
114 
115 
116 #ifdef __ARCH_WANT_OLD_STAT
117 
118 /*
119  * For backward compatibility?  Maybe this should be moved
120  * into arch/i386 instead?
121  */
122 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
123 {
124 	static int warncount = 5;
125 	struct __old_kernel_stat tmp;
126 
127 	if (warncount > 0) {
128 		warncount--;
129 		printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
130 			current->comm);
131 	} else if (warncount < 0) {
132 		/* it's laughable, but... */
133 		warncount = 0;
134 	}
135 
136 	memset(&tmp, 0, sizeof(struct __old_kernel_stat));
137 	tmp.st_dev = old_encode_dev(stat->dev);
138 	tmp.st_ino = stat->ino;
139 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
140 		return -EOVERFLOW;
141 	tmp.st_mode = stat->mode;
142 	tmp.st_nlink = stat->nlink;
143 	if (tmp.st_nlink != stat->nlink)
144 		return -EOVERFLOW;
145 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
146 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
147 	tmp.st_rdev = old_encode_dev(stat->rdev);
148 #if BITS_PER_LONG == 32
149 	if (stat->size > MAX_NON_LFS)
150 		return -EOVERFLOW;
151 #endif
152 	tmp.st_size = stat->size;
153 	tmp.st_atime = stat->atime.tv_sec;
154 	tmp.st_mtime = stat->mtime.tv_sec;
155 	tmp.st_ctime = stat->ctime.tv_sec;
156 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
157 }
158 
159 SYSCALL_DEFINE2(stat, const char __user *, filename,
160 		struct __old_kernel_stat __user *, statbuf)
161 {
162 	struct kstat stat;
163 	int error;
164 
165 	error = vfs_stat(filename, &stat);
166 	if (error)
167 		return error;
168 
169 	return cp_old_stat(&stat, statbuf);
170 }
171 
172 SYSCALL_DEFINE2(lstat, const char __user *, filename,
173 		struct __old_kernel_stat __user *, statbuf)
174 {
175 	struct kstat stat;
176 	int error;
177 
178 	error = vfs_lstat(filename, &stat);
179 	if (error)
180 		return error;
181 
182 	return cp_old_stat(&stat, statbuf);
183 }
184 
185 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
186 {
187 	struct kstat stat;
188 	int error = vfs_fstat(fd, &stat);
189 
190 	if (!error)
191 		error = cp_old_stat(&stat, statbuf);
192 
193 	return error;
194 }
195 
196 #endif /* __ARCH_WANT_OLD_STAT */
197 
198 #if BITS_PER_LONG == 32
199 #  define choose_32_64(a,b) a
200 #else
201 #  define choose_32_64(a,b) b
202 #endif
203 
204 #define valid_dev(x)  choose_32_64(old_valid_dev,new_valid_dev)(x)
205 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
206 
207 #ifndef INIT_STRUCT_STAT_PADDING
208 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
209 #endif
210 
211 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
212 {
213 	struct stat tmp;
214 
215 	if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
216 		return -EOVERFLOW;
217 #if BITS_PER_LONG == 32
218 	if (stat->size > MAX_NON_LFS)
219 		return -EOVERFLOW;
220 #endif
221 
222 	INIT_STRUCT_STAT_PADDING(tmp);
223 	tmp.st_dev = encode_dev(stat->dev);
224 	tmp.st_ino = stat->ino;
225 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
226 		return -EOVERFLOW;
227 	tmp.st_mode = stat->mode;
228 	tmp.st_nlink = stat->nlink;
229 	if (tmp.st_nlink != stat->nlink)
230 		return -EOVERFLOW;
231 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
232 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
233 	tmp.st_rdev = encode_dev(stat->rdev);
234 	tmp.st_size = stat->size;
235 	tmp.st_atime = stat->atime.tv_sec;
236 	tmp.st_mtime = stat->mtime.tv_sec;
237 	tmp.st_ctime = stat->ctime.tv_sec;
238 #ifdef STAT_HAVE_NSEC
239 	tmp.st_atime_nsec = stat->atime.tv_nsec;
240 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
241 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
242 #endif
243 	tmp.st_blocks = stat->blocks;
244 	tmp.st_blksize = stat->blksize;
245 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
246 }
247 
248 SYSCALL_DEFINE2(newstat, const char __user *, filename,
249 		struct stat __user *, statbuf)
250 {
251 	struct kstat stat;
252 	int error = vfs_stat(filename, &stat);
253 
254 	if (error)
255 		return error;
256 	return cp_new_stat(&stat, statbuf);
257 }
258 
259 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
260 		struct stat __user *, statbuf)
261 {
262 	struct kstat stat;
263 	int error;
264 
265 	error = vfs_lstat(filename, &stat);
266 	if (error)
267 		return error;
268 
269 	return cp_new_stat(&stat, statbuf);
270 }
271 
272 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
273 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
274 		struct stat __user *, statbuf, int, flag)
275 {
276 	struct kstat stat;
277 	int error;
278 
279 	error = vfs_fstatat(dfd, filename, &stat, flag);
280 	if (error)
281 		return error;
282 	return cp_new_stat(&stat, statbuf);
283 }
284 #endif
285 
286 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
287 {
288 	struct kstat stat;
289 	int error = vfs_fstat(fd, &stat);
290 
291 	if (!error)
292 		error = cp_new_stat(&stat, statbuf);
293 
294 	return error;
295 }
296 
297 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
298 		char __user *, buf, int, bufsiz)
299 {
300 	struct path path;
301 	int error;
302 	int empty = 0;
303 	unsigned int lookup_flags = LOOKUP_EMPTY;
304 
305 	if (bufsiz <= 0)
306 		return -EINVAL;
307 
308 retry:
309 	error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
310 	if (!error) {
311 		struct inode *inode = path.dentry->d_inode;
312 
313 		error = empty ? -ENOENT : -EINVAL;
314 		if (inode->i_op->readlink) {
315 			error = security_inode_readlink(path.dentry);
316 			if (!error) {
317 				touch_atime(&path);
318 				error = inode->i_op->readlink(path.dentry,
319 							      buf, bufsiz);
320 			}
321 		}
322 		path_put(&path);
323 		if (retry_estale(error, lookup_flags)) {
324 			lookup_flags |= LOOKUP_REVAL;
325 			goto retry;
326 		}
327 	}
328 	return error;
329 }
330 
331 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
332 		int, bufsiz)
333 {
334 	return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
335 }
336 
337 
338 /* ---------- LFS-64 ----------- */
339 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
340 
341 #ifndef INIT_STRUCT_STAT64_PADDING
342 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
343 #endif
344 
345 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
346 {
347 	struct stat64 tmp;
348 
349 	INIT_STRUCT_STAT64_PADDING(tmp);
350 #ifdef CONFIG_MIPS
351 	/* mips has weird padding, so we don't get 64 bits there */
352 	if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
353 		return -EOVERFLOW;
354 	tmp.st_dev = new_encode_dev(stat->dev);
355 	tmp.st_rdev = new_encode_dev(stat->rdev);
356 #else
357 	tmp.st_dev = huge_encode_dev(stat->dev);
358 	tmp.st_rdev = huge_encode_dev(stat->rdev);
359 #endif
360 	tmp.st_ino = stat->ino;
361 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
362 		return -EOVERFLOW;
363 #ifdef STAT64_HAS_BROKEN_ST_INO
364 	tmp.__st_ino = stat->ino;
365 #endif
366 	tmp.st_mode = stat->mode;
367 	tmp.st_nlink = stat->nlink;
368 	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
369 	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
370 	tmp.st_atime = stat->atime.tv_sec;
371 	tmp.st_atime_nsec = stat->atime.tv_nsec;
372 	tmp.st_mtime = stat->mtime.tv_sec;
373 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
374 	tmp.st_ctime = stat->ctime.tv_sec;
375 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
376 	tmp.st_size = stat->size;
377 	tmp.st_blocks = stat->blocks;
378 	tmp.st_blksize = stat->blksize;
379 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
380 }
381 
382 SYSCALL_DEFINE2(stat64, const char __user *, filename,
383 		struct stat64 __user *, statbuf)
384 {
385 	struct kstat stat;
386 	int error = vfs_stat(filename, &stat);
387 
388 	if (!error)
389 		error = cp_new_stat64(&stat, statbuf);
390 
391 	return error;
392 }
393 
394 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
395 		struct stat64 __user *, statbuf)
396 {
397 	struct kstat stat;
398 	int error = vfs_lstat(filename, &stat);
399 
400 	if (!error)
401 		error = cp_new_stat64(&stat, statbuf);
402 
403 	return error;
404 }
405 
406 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
407 {
408 	struct kstat stat;
409 	int error = vfs_fstat(fd, &stat);
410 
411 	if (!error)
412 		error = cp_new_stat64(&stat, statbuf);
413 
414 	return error;
415 }
416 
417 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
418 		struct stat64 __user *, statbuf, int, flag)
419 {
420 	struct kstat stat;
421 	int error;
422 
423 	error = vfs_fstatat(dfd, filename, &stat, flag);
424 	if (error)
425 		return error;
426 	return cp_new_stat64(&stat, statbuf);
427 }
428 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
429 
430 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
431 void __inode_add_bytes(struct inode *inode, loff_t bytes)
432 {
433 	inode->i_blocks += bytes >> 9;
434 	bytes &= 511;
435 	inode->i_bytes += bytes;
436 	if (inode->i_bytes >= 512) {
437 		inode->i_blocks++;
438 		inode->i_bytes -= 512;
439 	}
440 }
441 
442 void inode_add_bytes(struct inode *inode, loff_t bytes)
443 {
444 	spin_lock(&inode->i_lock);
445 	__inode_add_bytes(inode, bytes);
446 	spin_unlock(&inode->i_lock);
447 }
448 
449 EXPORT_SYMBOL(inode_add_bytes);
450 
451 void inode_sub_bytes(struct inode *inode, loff_t bytes)
452 {
453 	spin_lock(&inode->i_lock);
454 	inode->i_blocks -= bytes >> 9;
455 	bytes &= 511;
456 	if (inode->i_bytes < bytes) {
457 		inode->i_blocks--;
458 		inode->i_bytes += 512;
459 	}
460 	inode->i_bytes -= bytes;
461 	spin_unlock(&inode->i_lock);
462 }
463 
464 EXPORT_SYMBOL(inode_sub_bytes);
465 
466 loff_t inode_get_bytes(struct inode *inode)
467 {
468 	loff_t ret;
469 
470 	spin_lock(&inode->i_lock);
471 	ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
472 	spin_unlock(&inode->i_lock);
473 	return ret;
474 }
475 
476 EXPORT_SYMBOL(inode_get_bytes);
477 
478 void inode_set_bytes(struct inode *inode, loff_t bytes)
479 {
480 	/* Caller is here responsible for sufficient locking
481 	 * (ie. inode->i_lock) */
482 	inode->i_blocks = bytes >> 9;
483 	inode->i_bytes = bytes & 511;
484 }
485 
486 EXPORT_SYMBOL(inode_set_bytes);
487